Diphtheria toxin-induced channels in Vero cells selective for monovalent cations

International Nuclear Information System (INIS)

Sandvig, K.; Olsnes, S.

1988-01-01

Ion fluxes associated with translocation of diphtheria toxin across the surface membrane of Vero cells were studied. When cells with surface-bound toxin were exposed to low pH to induce toxin entry, the cells became permeable to Na+, K+, H+, choline+, and glucosamine+. There was no increased permeability to Cl-, SO4(-2), glucose, or sucrose, whereas the uptake of 45 Ca2+ was slightly increased. The influx of Ca2+, which appears to be different from that of monovalent cations, was reduced by several inhibitors of anion transport and by verapamil, Mn2+, Co2+, and Ca2+, but not by Mg2+. The toxin-induced fluxes of N+, K+, and protons were inhibited by Cd2+. Cd2+ also protected the cells against intoxication by diphtheria toxin, suggesting that the open cation-selective channel is required for toxin translocation. The involvement of the toxin receptor is discussed

Effects of anti-inflammatory drugs on fever and neutrophilia induced by Clostridium difficile toxin B

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R. A. Cardoso

1996-01-01

Full Text Available This study investigated the ability of Clostridium difficile toxin B, isolated from the VPI 10463 strain, to induce fever and neutrophilia in rats. Intravenous injection of toxin B (0.005–0.5 μg/kg evoked a dose-dependent increase in body temperature. The febrile response to 0.5 μg/kg of the toxin started in 2.5 h, peaked at 5 h, and subsided fully within 24 h. Toxin B also induced a dosedependent neutrophilia. Pretreatment with indomethacin (2 mg/kg, i.p. did not affect the neutrophilia induced by toxin B, but significantly reduced the febrile response measured 4 to 8 h after toxin B injection. Dexamethasone (0.5 mg/ kg also markedly diminished the febrile response induced by toxin B. These results show that Clostridium difficile toxin B induced a febrile response susceptible to inhibition by dexamethasone and indomethacin. Furthermore, they suggest that prostaglandins are not involved in the neutrophilia caused by this toxin.

Shiga toxin induces membrane reorganization and formation of long range lipid order

DEFF Research Database (Denmark)

Solovyeva, Vita; Johannes, Ludger; Simonsen, Adam Cohen

2015-01-01

membrane reordering. When Shiga toxin was added above the lipid chain melting temperature, the toxin interaction with the membrane induced rearrangement and clustering of Gb3 lipids that resulted in the long range order and alignment of lipids in gel domains. The toxin induced redistribution of Gb3 lipids...... inside gel domains is governed by the temperature at which Shiga toxin was added to the membrane: above or below the phase transition. The temperature is thus one of the critical factors controlling lipid organization and texture in the presence of Shiga toxin. Lipid chain ordering imposed by Shiga toxin...... binding can be another factor driving the reconstruction of lipid organization and crystallization of lipids inside gel domains....

Association of Fluid Accumulation with Clinical Outcomes in Critically Ill Children with Severe Sepsis

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Chen, Jiao; Li, Xiaozhong; Bai, Zhenjiang; Fang, Fang; Hua, Jun; Li, Ying; Pan, Jian; Wang, Jian; Feng, Xing; Li, Yanhong

2016-01-01

Objective To evaluate whether early and acquired daily fluid overload (FO), as well as fluctuations in fluid accumulation, were associated with adverse outcomes in critically ill children with severe sepsis. Methods This study enrolled 202 children in a pediatric intensive care unit (PICU) with severe sepsis. Early fluid overload was defined as ≥5% fluid accumulation occurring in the first 24 hours of PICU admission. The maximum daily fluid accumulation ≥5% occurring during the next 6 days in patients with at least 48 hours of PICU stay was defined as PICU-acquired daily fluid overload. The fluctuation in fluid accumulation was calculated as the difference between the maximum and the minimum daily fluid accumulation obtained during the first 7 days after admission. Results Of the 202 patients, 61 (30.2%) died during PICU stay. Among all patients, 41 (20.3%) experienced early fluid overload, including 9 with a FO ≥10%. Among patients with at least 48 hours of PICU stay (n = 154), 36 (23.4%) developed PICU-acquired daily fluid overload, including 2 with a FO ≥10%. Both early fluid overload (AOR = 1.20; 95% CI 1.08–1.33; P = 0.001; n = 202) and PICU-acquired daily fluid overload (AOR = 5.47 per log increase; 95% CI 1.15–25.96; P = 0.032; n = 154) were independent risk factors associated with mortality after adjusting for age, illness severity, etc. However, fluctuations in fluid accumulation were not associated with mortality after adjustment. Length of PICU stay increased with greater fluctuations in fluid accumulation in all patients with at least 48 hours of PICU stay (FO fluid overload achieved an area under-the-receiver-operating-characteristic curve of 0.74 (95% CI 0.65–0.82; P fluid overload were independently associated with PICU mortality in children with severe sepsis. PMID:27467522

Pertussis toxin inhibits somatostatin-induced K+ conductance in human pituitary tumor cells

International Nuclear Information System (INIS)

Yamashita, N.; Kojima, I.; Shibuya, N.; Ogata, E.

1987-01-01

The effect of pertussis toxin on somatostatin-induced K + current was examined in dissociated human pituitary tumor cells obtained from two acromegalic patients. Somatostatin-induced hyperpolarization or K + current was observed in 20 of 23 cells in adenoma 1 and 10 of 11 cells in adenoma 2. After treatment with pertussis toxin for 24 h, these responses were completely suppressed (0/14 in adenoma, 1, 0/10 in adenoma 2). Spontaneous action potentials, K + , Na + , and Ca 2+ currents were well preserved after pertussis toxin treatment. When crude membrane fraction was incubated with [ 32 P]NAD, a 41K protein was ADP-ribosylated by pertussis toxin. Hormone release was inhibited by somatostatin and this inhibition was blocked by pertussis toxin treatment

Membrane invagination induced by Shiga toxin B-subunit

DEFF Research Database (Denmark)

Pezeshkian, W.; Hansen, Allan Grønhøj; Johannes, Ludger

2016-01-01

-atom molecular dynamics and Monte Carlo simulations we show that the molecular architecture of STxB enables the following sequence of events: the Gb3 binding sites on STxB are arranged such that tight avidity-based binding results in a small increment of local curvature. Membrane-mediated clustering of several...... toxin molecules then creates a tubular membrane invagination that drives toxin entry into the cell. This mechanism requires: (1) a precise molecular architecture of the STxB binding sites; (2) a fluid bilayer in order for the tubular invagination to form. Although, STxB binding to the membrane requires...... specific interactions with Gb3 lipids, our study points to a generic molecular design principle for clathrin-independent endocytosis of nanoparticles....

Accumulation, Biotransformation, Histopathology and Paralysis in the Pacific Calico Scallop Argopecten ventricosus by the Paralyzing Toxins of the Dinoflagellate Gymnodinium catenatum

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Rosalba Alonso-Rodriguez

2012-05-01

Full Text Available The dinoflagellate Gymnodinium catenatum produces paralyzing shellfish poisons that are consumed and accumulated by bivalves. We performed short-term feeding experiments to examine ingestion, accumulation, biotransformation, histopathology, and paralysis in the juvenile Pacific calico scallop Argopecten ventricosus that consume this dinoflagellate. Depletion of algal cells was measured in closed systems. Histopathological preparations were microscopically analyzed. Paralysis was observed and the time of recovery recorded. Accumulation and possible biotransformation of toxins were measured by HPLC analysis. Feeding activity in treated scallops showed that scallops produced pseudofeces, ingestion rates decreased at 8 h; approximately 60% of the scallops were paralyzed and melanin production and hemocyte aggregation were observed in several tissues at 15 h. HPLC analysis showed that the only toxins present in the dinoflagellates and scallops were the N-sulfo-carbamoyl toxins (C1, C2; after hydrolysis, the carbamate toxins (epimers GTX2/3 were present. C1 and C2 toxins were most common in the mantle, followed by the digestive gland and stomach-complex, adductor muscle, kidney and rectum group, and finally, gills. Toxin profiles in scallop tissue were similar to the dinoflagellate; biotransformations were not present in the scallops in this short-term feeding experiment.

Accumulation of cyanobacterial toxins in freshwater 'seafood' and its consequences for public health: A review

International Nuclear Information System (INIS)

Ibelings, Bas W.; Chorus, Ingrid

2007-01-01

This review summarizes and discusses the current understanding of human exposure to cyanobacterial toxins in 'seafood' collected from freshwater and coastal areas. The review consists of three parts: (a) the existing literature on concentrations of cyanobacterial toxins in seafood is reviewed, and the likelihood of bioaccumulation discussed; (b) we derive cyanotoxin doses likely to occur through seafood consumption and propose guideline values for seafood and compare these to guidelines for drinking water; and (c) we discuss means to assess, control or mitigate the risks of exposure to cyanotoxins through seafood consumption. This is discussed in the context of two specific procedures, the food specific HACCP-approach and the water-specific Water Safety Plan approach by the WHO. Risks of exposure to cyanotoxins in food are sometimes underestimated. Risk assessments should acknowledge this and investigate the partitioning of exposure between drinking-water and food, which may vary depending on local circumstances. - Accumulation of cyanobacterial toxins in freshwater 'seafood'

Fluid flow enhances the effectiveness of toxin export by aquatic microorganisms: a first-passage perspective

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Licata, Nicholas; Clark, Aaron

2014-03-01

Aquatic microorganisms face a variety of challenges in the course of development. One central challenge is efficiently regulating the export of toxic molecules inside the developing embryo. The strategies employed should be robust with respect to the variable ocean environment and limit the chances that exported toxins are reabsorbed. In this talk we consider the first-passage problem for the uptake of exported toxins by a spherical embryo. A perturbative solution of the advection-diffusion equation reveals that a concentration boundary layer forms in the vicinity of the embryo, and that fluid flow enhances the effectiveness of toxin export. We highlight connections between the model results and recent experiments on the development of sea urchin embryos. We acknowledge financial support from the University of Michigan-Dearobrn CASL Faculty Summer Research Grant.

Association of Fluid Accumulation with Clinical Outcomes in Critically Ill Children with Severe Sepsis.

Directory of Open Access Journals (Sweden)

Jiao Chen

Full Text Available To evaluate whether early and acquired daily fluid overload (FO, as well as fluctuations in fluid accumulation, were associated with adverse outcomes in critically ill children with severe sepsis.This study enrolled 202 children in a pediatric intensive care unit (PICU with severe sepsis. Early fluid overload was defined as ≥5% fluid accumulation occurring in the first 24 hours of PICU admission. The maximum daily fluid accumulation ≥5% occurring during the next 6 days in patients with at least 48 hours of PICU stay was defined as PICU-acquired daily fluid overload. The fluctuation in fluid accumulation was calculated as the difference between the maximum and the minimum daily fluid accumulation obtained during the first 7 days after admission.Of the 202 patients, 61 (30.2% died during PICU stay. Among all patients, 41 (20.3% experienced early fluid overload, including 9 with a FO ≥10%. Among patients with at least 48 hours of PICU stay (n = 154, 36 (23.4% developed PICU-acquired daily fluid overload, including 2 with a FO ≥10%. Both early fluid overload (AOR = 1.20; 95% CI 1.08-1.33; P = 0.001; n = 202 and PICU-acquired daily fluid overload (AOR = 5.47 per log increase; 95% CI 1.15-25.96; P = 0.032; n = 154 were independent risk factors associated with mortality after adjusting for age, illness severity, etc. However, fluctuations in fluid accumulation were not associated with mortality after adjustment. Length of PICU stay increased with greater fluctuations in fluid accumulation in all patients with at least 48 hours of PICU stay (FO <5%, 5%-10% vs. ≥10%: 4 [3-8], 7 [4-11] vs. 10 [6-16] days; P <0.001; n = 154 and in survivors (4 [3-8], 7 [5-11] vs. 10 [5-15] days; P <0.001; n = 121. Early fluid overload achieved an area under-the-receiver-operating-characteristic curve of 0.74 (95% CI 0.65-0.82; P <0.001; n = 202 for predicting mortality in patients with severe sepsis, with a sensitivity of 67.2% and a specificity of 80.1% at the

The protective activity of tea catechins against experimental infection by Vibrio cholerae O1.

Science.gov (United States)

Toda, M; Okubo, S; Ikigai, H; Suzuki, T; Suzuki, Y; Hara, Y; Shimamura, T

1992-01-01

Tea catechins inhibited the fluid accumulation induced by cholera toxin in sealed adult mice. The catechins also reduced fluid accumulation by Vibrio cholerae O1 in ligated intestinal loops of rabbits. These findings suggest that tea catechins may possess protective activity against V. cholerae O1.

Removal of zearalenone toxin from synthetics gastric and body fluids using talc and diatomite: a batch kinetic study.

Science.gov (United States)

Sprynskyy, Myroslav; Gadzała-Kopciuch, Renata; Nowak, Karolina; Buszewski, Bogusław

2012-06-01

Adsorption kinetics of zearalenone (ZEA) toxin from synthetic gastric fluid (SGF) and synthetic body fluid (SBF) by talc and diatomite was studied in the batch experiments. Chemical composition, morphology and structure of the used adsorbents were examined by scanning electron microscopy, FTIR spectroscopy and low-temperature nitrogen adsorption/desorption method. High performance liquid chromatography (HPLC) method was used for ZEA determining. The study results showed that ZEA is more effectively adsorbed on the talc (73% and 54% from SGF and SBF respectively). The efficiency on the diatomite was lower (53% and 42% from SGF and SBF respectively). The first order kinetics model was applied to describe the adsorption process. Rate of the ZEA adsorption from SGF is very rapid initially with about 95% of amount of the toxin adsorbed during first 5 min, while ZEA is adsorbed from SBF in two steps. The values of determined Gibbs free energy of adsorption (from -13 to -17 kJ/mol) indicated that adsorption of ZEA toxin by the both adsorbents are spontaneous and exothermic. Copyright © 2012 Elsevier B.V. All rights reserved.

The role of toxins in Clostridium difficile infection.

Science.gov (United States)

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.

Hydrocarbon accumulation in deep fluid modified carbonate rock in the Tarim Basin

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

The activities of deep fluid are regionalized in the Tarim Basin. By analyzing the REE in core samples and crude oil, carbon isotope of carbon dioxide and inclusion temperature measurement in the west of the Tazhong Uplift in the western Tarim Basin, all the evidence confirms the existence of deep fluid. The deep fluid below the basin floor moved up into the basin through discordogenic fauit and volcanicity to cause corrosion and metaaomatosis of carbonate rock by exchange of matter and energy. The pore structure and permeability of the carbonate reservoirs were improved, making the carbonate reservoirs an excellent type of deeply buried modification. The fluorite ore belts discovered along the large fault and the volcanic area in the west of the Tazhong Uplift are the outcome of deep fluid action. Such carbonate reservoirs are the main type of reservoirs in the Tazhong 45 oilfield. The carbonate reservoirs in well YM 7 are improved obviously by thermal fluid dolomitization. The origin and territory of deep fluid are associated with the discordogenic fault and volcanicity in the basin. The discordogenic fault and volcanic area may be the pointer of looking for the deep fluid modified reservoirs. The primary characteristics of hydrocarbon accumulation in deep fluid reconstructed carbonate rock are summarized as accumulation near the large fault and volcano passage, late-period hydrocarbon accumulation after volcanic activity, and subtle trap reservoirs controlled by lithology.

Accumulation of cyanobacterial toxins in freshwater 'seafood' and its consequences for public health: A review

Energy Technology Data Exchange (ETDEWEB)

Ibelings, Bas W. [Eawag, Swiss Federal Institute of Aquatic Sciences and Technology, Centre of Ecology, Evolution and Biogeochemistry, Seestrasse 79, CH-6047 Kastanienbaum (Switzerland); Netherlands Institute of Ecology, Centre for Limnology, Rijksstraatweg 6, 3631 AC, Nieuwersluis (Netherlands)], E-mail: bas.ibelings@eawag.ch; Chorus, Ingrid [German Federal Environment Agency, Corrensplatz 1, 14195 Berlin (Germany)], E-mail: ingrid.chorus@uba.de

2007-11-15

This review summarizes and discusses the current understanding of human exposure to cyanobacterial toxins in 'seafood' collected from freshwater and coastal areas. The review consists of three parts: (a) the existing literature on concentrations of cyanobacterial toxins in seafood is reviewed, and the likelihood of bioaccumulation discussed; (b) we derive cyanotoxin doses likely to occur through seafood consumption and propose guideline values for seafood and compare these to guidelines for drinking water; and (c) we discuss means to assess, control or mitigate the risks of exposure to cyanotoxins through seafood consumption. This is discussed in the context of two specific procedures, the food specific HACCP-approach and the water-specific Water Safety Plan approach by the WHO. Risks of exposure to cyanotoxins in food are sometimes underestimated. Risk assessments should acknowledge this and investigate the partitioning of exposure between drinking-water and food, which may vary depending on local circumstances. - Accumulation of cyanobacterial toxins in freshwater 'seafood'.

Selenium deficiency aggravates T-2 toxin-induced injury of primary neonatal rat cardiomyocytes through ER stress.

Science.gov (United States)

Xu, Jing; Pan, Shengchi; Gan, Fang; Hao, Shu; Liu, Dandan; Xu, Haibin; Huang, Kehe

2018-04-01

Keshan disease is a potentially fatal cardiomyopathy in humans. Selenium deficiency, T-2 toxin, and myocarditis virus are thought to be the major factors contributing to Keshan disease. But the relationship among these three factors is poorly described. This study aims to explore whether selenium deficiency aggravates T-2 toxin-induced cardiomyocyte injury and its underlying mechanism. Cardiomyocytes were isolated from neonatal rat and cultured at the physiological (2.0 μM) or lower concentrations of selenium with different concentrations of T-2 toxin. Our results showed that selenium deficiencies aggravated T-2 toxin-induced cardiomyocyte injury in a concentration-dependent manner as demonstrated by MTT bioassay, LDH activity, reactive oxygen species levels and caspase 3 protein expressions. T-2 toxin treatment significantly increased mRNA expressions for stress proteins GRP78 and CHOP in cardiomyocytes compared with the control. Selenium deficiencies further promoted GRP78, CHOP and p-eIF2α expressions. Knockdown of CHOP by the specific small interfering RNA eliminated the effect of selenium deficiencies on T-2 toxin-induced injury. It could be concluded that selenium deficiency aggravates T-2 toxin-induced cardiomyocyte injury through initiating more aggressive endoplasmic reticulum stress. Copyright © 2018 Elsevier B.V. All rights reserved.

Cardiac-specific catalase overexpression rescues anthrax lethal toxin-induced cardiac contractile dysfunction: role of oxidative stress and autophagy.

Science.gov (United States)

Kandadi, Machender R; Yu, Xuejun; Frankel, Arthur E; Ren, Jun

2012-11-07

Lethal and edema toxins secreted by Bacillus anthracis during anthrax infection were found to incite serious cardiovascular complications. However, the underlying mechanisms in anthrax lethal toxin-induced cardiac anomalies remain unknown. This study was designed to evaluate the impact of antioxidant enzyme catalase in anthrax lethal toxin-induced cardiomyocyte contractile dysfunction. Wild type (WT) and cardiac-specific catalase overexpression mice were challenged with lethal toxin (2 μg/g, intraperotineally (i.p.)). Cardiomyocyte contractile and intracellular Ca(2+) properties were assessed 18 h later using an IonOptix edge-detection system. Proteasome function was assessed using chymotrypsin-like and caspase-like activities. GFP-LC3 puncta and Western blot analysis were used to evaluate autophagy and protein ubiquitination. Lethal toxin exposure suppressed cardiomyocyte contractile function (suppressed peak shortening, maximal velocity of shortening/re-lengthening, prolonged duration of shortening/re-lengthening, and impaired intracellular Ca(2+) handling), the effects of which were alleviated by catalase. In addition, lethal toxin triggered autophagy, mitochondrial and ubiquitin-proteasome defects, the effects of which were mitigated by catalase. Pretreatment of cardiomyocytes from catalase mice with the autophagy inducer rapamycin significantly attenuated or ablated catalase-offered protection against lethal toxin-induced cardiomyocyte dysfunction. On the other hand, the autophagy inhibitor 3-MA ablated or significantly attenuated lethal toxin-induced cardiomyocyte contractile anomalies. Our results suggest that catalase is protective against anthrax lethal toxin-induced cardiomyocyte contractile and intracellular Ca(2+) anomalies, possibly through regulation of autophagy and mitochondrial function.

Accumulation of Colloidal Particles in Flow Junctions Induced by Fluid Flow and Diffusiophoresis

Science.gov (United States)

Shin, Sangwoo; Ault, Jesse T.; Warren, Patrick B.; Stone, Howard A.

2017-10-01

The flow of solutions containing solutes and colloidal particles in porous media is widely found in systems including underground aquifers, hydraulic fractures, estuarine or coastal habitats, water filtration systems, etc. In such systems, solute gradients occur when there is a local change in the solute concentration. While the effects of solute gradients have been found to be important for many applications, we observe an unexpected colloidal behavior in porous media driven by the combination of solute gradients and the fluid flow. When two flows with different solute concentrations are in contact near a junction, a sharp solute gradient is formed at the interface, which may allow strong diffusiophoresis of the particles directed against the flow. Consequently, the particles accumulate near the pore entrance, rapidly approaching the packing limit. These colloidal dynamics have important implications for the clogging of a porous medium, where particles that are orders of magnitude smaller than the pore width can accumulate and block the pores within a short period of time. We also show that this effect can be exploited as a useful tool for preconcentrating biomolecules for rapid bioassays.

Accumulation of Colloidal Particles in Flow Junctions Induced by Fluid Flow and Diffusiophoresis

Energy Technology Data Exchange (ETDEWEB)

Shin, Sangwoo [Univ. of Hawaii at Manoa, Honolulu, HI (United States); Ault, Jesse T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Warren, Patrick B. [Unilever R& D Port Sunlight, Wirral (United Kingdom); Stone, Howard A. [Princeton Univ., Princeton, NJ (United States)

2017-11-16

The flow of solutions containing solutes and colloidal particles in porous media is widely found in systems including underground aquifers, hydraulic fractures, estuarine or coastal habitats, water filtration systems, etc. In such systems, solute gradients occur when there is a local change in the solute concentration. While the effects of solute gradients have been found to be important for many applications, we observe an unexpected colloidal behavior in porous media driven by the combination of solute gradients and the fluid flow. When two flows with different solute concentrations are in contact near a junction, a sharp solute gradient is formed at the interface, which may allow strong diffusiophoresis of the particles directed against the flow. Consequently, the particles accumulate near the pore entrance, rapidly approaching the packing limit. These colloidal dynamics have important implications for the clogging of a porous medium, where particles that are orders of magnitude smaller than the pore width can accumulate and block the pores within a short period of time. As a result, we also show that this effect can be exploited as a useful tool for preconcentrating biomolecules for rapid bioassays.

Filaggrin-dependent secretion of sphingomyelinase protects against staphylococcal α-toxin-induced keratinocyte death.

Science.gov (United States)

Brauweiler, Anne M; Bin, Lianghua; Kim, Byung Eui; Oyoshi, Michiko K; Geha, Raif S; Goleva, Elena; Leung, Donald Y M

2013-02-01

The skin of patients with atopic dermatitis (AD) has defects in keratinocyte differentiation, particularly in expression of the epidermal barrier protein filaggrin. AD skin lesions are often exacerbated by Staphylococcus aureus-mediated secretion of the virulence factor α-toxin. It is unknown whether lack of keratinocyte differentiation predisposes to enhanced lethality from staphylococcal toxins. We investigated whether keratinocyte differentiation and filaggrin expression protect against cell death induced by staphylococcal α-toxin. Filaggrin-deficient primary keratinocytes were generated through small interfering RNA gene knockdown. RNA expression was determined by using real-time PCR. Cell death was determined by using the lactate dehydrogenase assay. Keratinocyte cell survival in filaggrin-deficient (ft/ft) mouse skin biopsies was determined based on Keratin 5 staining. α-Toxin heptamer formation and acid sphingomyelinase expression were determined by means of immunoblotting. We found that filaggrin expression, occurring as the result of keratinocyte differentiation, significantly inhibits staphylococcal α-toxin-mediated pathogenicity. Furthermore, filaggrin plays a crucial role in protecting cells by mediating the secretion of sphingomyelinase, an enzyme that reduces the number of α-toxin binding sites on the keratinocyte surface. Finally, we determined that sphingomyelinase enzymatic activity directly prevents α-toxin binding and protects keratinocytes against α-toxin-induced cytotoxicity. The current study introduces the novel concept that S aureus α-toxin preferentially targets and destroys filaggrin-deficient keratinocytes. It also provides a mechanism to explain the increased propensity for S aureus-mediated exacerbation of AD skin disease. Copyright © 2012 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

Induction of Manduca sexta Larvae Caspases Expression in Midgut Cells by Bacillus thuringiensis Cry1Ab Toxin

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Helena Porta

2011-01-01

Full Text Available Bacillus thuringiensis produces crystal toxins known as Cry that are highly selective against important agricultural and human health-related insect pests. Cry proteins are pore-forming toxins that interact with specific receptors in the midgut cell membrane of susceptible larvae making pores that cause osmotic shock, leading finally to insect death. In the case of pore-forming toxins that are specific to mammalian cells, death responses at low doses may induce apoptosis or pyroptosis, depending on the cell type. The death mechanism induced by Cry toxins in insect midgut cells is poorly understood. Here, we analyze the caspases expression by RT-PCR analysis, showing that the initial response of Manduca sexta midgut cells after low dose of Cry1Ab toxin administration involves a fast and transient accumulation of caspase-1 mRNA, suggesting that pyroptosis was activated by Cry1Ab toxin as an initial response but was repressed later. In contrast, caspase-3 mRNA requires a longer period of time of toxin exposure to be activated but presents a sustained activation, suggesting that apoptosis may be a cell death mechanism induced also at low dose of toxin.

Cardiac-specific catalase overexpression rescues anthrax lethal toxin-induced cardiac contractile dysfunction: role of oxidative stress and autophagy

Directory of Open Access Journals (Sweden)

Kandadi Machender R

2012-11-01

Full Text Available Abstract Background Lethal and edema toxins secreted by Bacillus anthracis during anthrax infection were found to incite serious cardiovascular complications. However, the underlying mechanisms in anthrax lethal toxin-induced cardiac anomalies remain unknown. This study was designed to evaluate the impact of antioxidant enzyme catalase in anthrax lethal toxin-induced cardiomyocyte contractile dysfunction. Methods Wild type (WT and cardiac-specific catalase overexpression mice were challenged with lethal toxin (2 μg/g, intraperotineally (i.p.. Cardiomyocyte contractile and intracellular Ca2+ properties were assessed 18 h later using an IonOptix edge-detection system. Proteasome function was assessed using chymotrypsin-like and caspase-like activities. GFP-LC3 puncta and Western blot analysis were used to evaluate autophagy and protein ubiquitination. Results Lethal toxin exposure suppressed cardiomyocyte contractile function (suppressed peak shortening, maximal velocity of shortening/re-lengthening, prolonged duration of shortening/re-lengthening, and impaired intracellular Ca2+ handling, the effects of which were alleviated by catalase. In addition, lethal toxin triggered autophagy, mitochondrial and ubiquitin-proteasome defects, the effects of which were mitigated by catalase. Pretreatment of cardiomyocytes from catalase mice with the autophagy inducer rapamycin significantly attenuated or ablated catalase-offered protection against lethal toxin-induced cardiomyocyte dysfunction. On the other hand, the autophagy inhibitor 3-MA ablated or significantly attenuated lethal toxin-induced cardiomyocyte contractile anomalies. Conclusions Our results suggest that catalase is protective against anthrax lethal toxin-induced cardiomyocyte contractile and intracellular Ca2+ anomalies, possibly through regulation of autophagy and mitochondrial function.

K2 killer toxin-induced physiological changes in the yeast Saccharomyces cerevisiae.

Science.gov (United States)

Orentaite, Irma; Poranen, Minna M; Oksanen, Hanna M; Daugelavicius, Rimantas; Bamford, Dennis H

2016-03-01

Saccharomyces cerevisiae cells produce killer toxins, such as K1, K2 and K28, that can modulate the growth of other yeasts giving advantage for the killer strains. Here we focused on the physiological changes induced by K2 toxin on a non-toxin-producing yeast strain as well as K1, K2 and K28 killer strains. Potentiometric measurements were adjusted to observe that K2 toxin immediately acts on the sensitive cells leading to membrane permeability. This correlated with reduced respiration activity, lowered intracellular ATP content and decrease in cell viability. However, we did not detect any significant ATP leakage from the cells treated by killer toxin K2. Strains producing heterologous toxins K1 and K28 were less sensitive to K2 than the non-toxin producing one suggesting partial cross-protection between the different killer systems. This phenomenon may be connected to the observed differences in respiratory activities of the killer strains and the non-toxin-producing strain at low pH. This might also have practical consequences in wine industry; both as beneficial ones in controlling contaminating yeasts and non-beneficial ones causing sluggish fermentation. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Late endosomal cholesterol accumulation leads to impaired intra-endosomal trafficking.

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Komla Sobo

Full Text Available BACKGROUND: Pathological accumulation of cholesterol in late endosomes is observed in lysosomal storage diseases such as Niemann-Pick type C. We here analyzed the effects of cholesterol accumulation in NPC cells, or as phenocopied by the drug U18666A, on late endosomes membrane organization and dynamics. METHODOLOGY/PRINCIPAL FINDINGS: Cholesterol accumulation did not lead to an increase in the raft to non-raft membrane ratio as anticipated. Strikingly, we observed a 2-3 fold increase in the size of the compartment. Most importantly, properties and dynamics of late endosomal intralumenal vesicles were altered as revealed by reduced late endosomal vacuolation induced by the mutant pore-forming toxin ASSP, reduced intoxication by the anthrax lethal toxin and inhibition of infection by the Vesicular Stomatitis Virus. CONCLUSIONS/SIGNIFICANCE: These results suggest that back fusion of intralumenal vesicles with the limiting membrane of late endosomes is dramatically perturbed upon cholesterol accumulation.

Cardiac-specific catalase overexpression rescues anthrax lethal toxin-induced cardiac contractile dysfunction: role of oxidative stress and autophagy

OpenAIRE

Kandadi, Machender R; Yu, Xuejun; Frankel, Arthur E; Ren, Jun

2012-01-01

Abstract Background Lethal and edema toxins secreted by Bacillus anthracis during anthrax infection were found to incite serious cardiovascular complications. However, the underlying mechanisms in anthrax lethal toxin-induced cardiac anomalies remain unknown. This study was designed to evaluate the impact of antioxidant enzyme catalase in anthrax lethal toxin-induced cardiomyocyte contractile dysfunction. Methods Wild type (WT) and cardiac-specific catalase overexpression mice were challenged...

Ciprofloxacin causes persister formation by inducing the TisB toxin in Escherichia coli.

Directory of Open Access Journals (Sweden)

Tobias Dörr

2010-02-01

Full Text Available Bacteria induce stress responses that protect the cell from lethal factors such as DNA-damaging agents. Bacterial populations also form persisters, dormant cells that are highly tolerant to antibiotics and play an important role in recalcitrance of biofilm infections. Stress response and dormancy appear to represent alternative strategies of cell survival. The mechanism of persister formation is unknown, but isolated persisters show increased levels of toxin/antitoxin (TA transcripts. We have found previously that one or more components of the SOS response induce persister formation after exposure to a DNA-damaging antibiotic. The SOS response induces several TA genes in Escherichia coli. Here, we show that a knockout of a particular SOS-TA locus, tisAB/istR, had a sharply decreased level of persisters tolerant to ciprofloxacin, an antibiotic that causes DNA damage. Step-wise administration of ciprofloxacin induced persister formation in a tisAB-dependent manner, and cells producing TisB toxin were tolerant to multiple antibiotics. TisB is a membrane peptide that was shown to decrease proton motive force and ATP levels, consistent with its role in forming dormant cells. These results suggest that a DNA damage-induced toxin controls production of multidrug tolerant cells and thus provide a model of persister formation.

Effects of X-irradiation on axonal sprouting induced by botulinum toxin

Energy Technology Data Exchange (ETDEWEB)

Gomez, S; Duchen, L W [National Hospital, London (UK); Hornsey, S [Hammersmith Hospital, London (UK). M.R.C. Cyclotron Unit

1982-01-01

The effect of X-irradiation on axonal sprouting of motor nerves induced by botulinum toxin was examined. Muscles of one leg in the mouse were X-irradiated (15Gy) prior to the injection of a locally paralysing dose of botulinum toxin. It was found that axonal sprouting occurred as expected, but the sprouts remained unmyelinated and many degenerated. Fewer new end-plates were formed, muscles remained more severely atrophied and supersensitive to acetylcholine and recovery of neuromuscular transmission was greatly delayed when compared with the effects of botulinum toxin alone. X-irradiation did not prevent sprouting but, probably by impairing Schwann cell proliferation, altered axon-Schwann cell relationships and prevented the maturation of newly-formed axons and the differentiation of new end-plates.

The Effects of Distention and Obstruction on the Accumulation of Fluid in the Lumen of Small Bowel of Dogs

Science.gov (United States)

Mishra, Nand K.; Appert, Hubert E.; Howard, John M.

1974-01-01

Fluid accumulation in either the obstructed upper or lower intestinal segments of the dog was found in most animals to be negligible. Distention pressures of 25 cm of water tended to reduce fluid accumulation within the intestinal lumen. These studies suggest that if the dog is comparable to man, the intraluminal accumulation of fluid in the obstructed small bowel of man might be due to alterations in blood supply to the intestine, rather than to obstruction per se, or the accumulated fluid originates proximal to the jejunum. PMID:4419581

Signal-based Gas Leakage Detection for Fluid Power Accumulators in Wind Turbines

DEFF Research Database (Denmark)

Liniger, Jesper; Sepehri, Nariman; N. Soltani, Mohsen

2017-01-01

This paper describes the development and application of a signal-based fault detection method for identifying gas leakage in hydraulic accumulators used in wind turbines. The method uses Multiresolution Signal Decomposition (MSD) based on wavelets for feature extraction from a~single fluid pressure...... measurement located close to the accumulator. Gas leakage is shown to create increased variations in this pressure signal. The Root Mean Square (RMS) of the detail coefficient Level 9 from the MSD is found as the most sensitive and robust fault indicator of gas leakage. The method is verified...... on an experimental setup allowing for the replication of the conditions for accumulators in wind turbines. Robustness is tested in a multi-fault environment where gas and external fluid leakage occurs simultaneously. In total, 24 experiments are performed, which show that the method is sensitive to gas leakage...

Algal Toxin Azaspiracid-1 Induces Early Neuronal Differentiation and Alters Peripherin Isoform Stoichiometry

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Linda V. Hjørnevik

2015-12-01

Full Text Available Azaspiracid-1 is an algal toxin that accumulates in edible mussels, and ingestion may result in human illness as manifested by vomiting and diarrhoea. When injected into mice, it causes neurotoxicological symptoms and death. Although it is well known that azaspiracid-1 is toxic to most cells and cell lines, little is known about its biological target(s. A rat PC12 cell line, commonly used as a model for the peripheral nervous system, was used to study the neurotoxicological effects of azaspiracid-1. Azaspiracid-1 induced differentiation-related morphological changes followed by a latter cell death. The differentiated phenotype showed peripherin-labelled neurite-like processes simultaneously as a specific isoform of peripherin was down-regulated. The precise mechanism behind this down-regulation remains uncertain. However, this study provides new insights into the neurological effects of azaspiracid-1 and into the biological significance of specific isoforms of peripherin.

Clostridium difficile toxin CDT induces formation of microtubule-based protrusions and increases adherence of bacteria.

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Carsten Schwan

2009-10-01

Full Text Available Clostridium difficile causes antibiotic-associated diarrhea and pseudomembranous colitis by production of the Rho GTPase-glucosylating toxins A and B. Recently emerging hypervirulent Clostridium difficile strains additionally produce the binary ADP-ribosyltransferase toxin CDT (Clostridium difficile transferase, which ADP-ribosylates actin and inhibits actin polymerization. Thus far, the role of CDT as a virulence factor is not understood. Here we report by using time-lapse- and immunofluorescence microscopy that CDT and other binary actin-ADP-ribosylating toxins, including Clostridium botulinum C2 toxin and Clostridium perfringens iota toxin, induce redistribution of microtubules and formation of long (up to >150 microm microtubule-based protrusions at the surface of intestinal epithelial cells. The toxins increase the length of decoration of microtubule plus-ends by EB1/3, CLIP-170 and CLIP-115 proteins and cause redistribution of the capture proteins CLASP2 and ACF7 from microtubules at the cell cortex into the cell interior. The CDT-induced microtubule protrusions form a dense meshwork at the cell surface, which wrap and embed bacterial cells, thereby largely increasing the adherence of Clostridia. The study describes a novel type of microtubule structure caused by less efficient microtubule capture and offers a new perspective for the pathogenetic role of CDT and other binary actin-ADP-ribosylating toxins in host-pathogen interactions.

Activation of AMPK inhibits cholera toxin stimulated chloride secretion in human and murine intestine.

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Ailín C Rogers

Full Text Available Increased intestinal chloride secretion through chloride channels, such as the cystic fibrosis transmembrane conductance regulator (CFTR, is one of the major molecular mechanisms underlying enterotoxigenic diarrhea. It has been demonstrated in the past that the intracellular energy sensing kinase, the AMP-activated protein kinase (AMPK, can inhibit CFTR opening. We hypothesized that pharmacological activation of AMPK can abrogate the increased chloride flux through CFTR occurring during cholera toxin (CTX mediated diarrhea. Chloride efflux was measured in isolated rat colonic crypts using real-time fluorescence imaging. AICAR and metformin were used to activate AMPK in the presence of the secretagogues CTX or forskolin (FSK. In order to substantiate our findings on the whole tissue level, short-circuit current (SCC was monitored in human and murine colonic mucosa using Ussing chambers. Furthermore, fluid accumulation was measured in excised intestinal loops. CTX and forskolin (FSK significantly increased chloride efflux in isolated colonic crypts. The increase in chloride efflux could be offset by using the AMPK activators AICAR and metformin. In human and mouse mucosal sheets, CTX and FSK increased SCC. AICAR and metformin inhibited the secretagogue induced rise in SCC, thereby confirming the findings made in isolated crypts. Moreover, AICAR decreased CTX stimulated fluid accumulation in excised intestinal segments. The present study suggests that pharmacological activation of AMPK effectively reduces CTX mediated increases in intestinal chloride secretion, which is a key factor for intestinal water accumulation. AMPK activators may therefore represent a supplemental treatment strategy for acute diarrheal illness.

Radiation-induced bilateral cystic frontal lobe necroses demonstrating a fluid-blood level; Case report

Energy Technology Data Exchange (ETDEWEB)

Mineura, Katsuyoshi; Sasajima, Toshio; Kowada, Masayoshi [Akita Univ. (Japan). School of Medicine; Ogawa, Toshihide

1992-02-01

A 41-year-old male developed radiation-induced bilateral cystic frontal lobe necroses after irradiation for an olfactory neuroblastoma. Computed tomography (CT) and magnetic resonance (MR) imaging revealed the lesions, one containing a fluid-blood level on CT scans and niveau formation on MR images. It was proved to be a coagulated hematoma within the cyst at surgery. Such a fluid-blood level in a radiation-induced cyst has never been reported, although hemorrhage frequently accompanies delayed radiation necrosis. Positron emission tomography with multiple tracers may be useful in differentiating cerebral radiation necrosis from tumor recurrence, because of absence of abnormal tracer accumulation. (author).

Slow food: insect prey and chitin induce phytohormone accumulation and gene expression in carnivorous Nepenthes plants.

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Yilamujiang, Ayufu; Reichelt, Michael; Mithöfer, Axel

2016-08-01

Carnivorous Nepenthes plants use modified leaves forming pitfall traps to capture and digest prey, mainly insects, for additional nutrient supply. These traps, so called pitchers, contain a plant-derived fluid composed of many hydrolytic enzymes and defence-related proteins. In this study, the prey-induced induction of corresponding genes of those proteins and a role for phytohormones in this process was analysed. Tissue from insect prey-fed, chitin- and phytohormone-challenged pitchers was harvested and analysed for selected gene expressions by a quantitative PCR technique. Phytohormone levels were determined by LC-MS/MS. Nepenthesin proteolytic activities were measured in the digestive fluid using a fluorescence substrate. Insect prey in the pitchers induced the accumulation of phytohormones such as jasmonates as well as the transcription of studied genes encoding a chitinase 3 and a protease (nepenthesin I), whereas a defence-related protein (PR-1) gene was not induced. Treatment with chitin as a component of the insects' exoskeleton triggered the accumulation of jasmonates, the expression of nepenthesin I and chitinase 3 genes similar to jasmonic acid treatment, and induced protease activity in the fluid. All detectable responses were slowly induced. The results suggest that upon insect prey catch a sequence of signals is initiated: (1) insect-derived chitin, (2) jasmonate as endogenous phytohormone signal, (3) the induction of digestive gene expression and (4) protein expression. This resembles a similar hierarchy of events as described from plant pathogen/herbivore interactions, supporting the idea that carnivory evolved from plant defences. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Endocardial botulinum toxin injection into ganglionated plexi in order to reduce atrial fibrillation inducibility

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А. Г. Стрельников

2016-01-01

Full Text Available Objective. Prior animal studies suggest that botulinum toxin injection into the epicardial fat pads can suppress atrial fibrillation (AF inducibility. The purpose of the present study was to assess the efficacy and safety of endocardial botulinum toxin injection into epicardial fat pads and intramyocardial left atrial ganglionated plexi (GP for preventing AF.Methods. Twenty-four dogs were separated into 3 groups: endocardial approach for botulinum toxin (Xeomin, Germany injection into epicardial fat pads and intramyocardial GPs; endocardial approach for placebo injection (0.9% normal saline; control 1; n = 8 and epicardial approach for botulinum toxin injection (control 2; n = 8.Results. A mean of 6.9±1.7 intramyocardial injections (10 U/0.2 mL at each and 3 injections (50 U/1 mL at each were administered into each site exhibiting a positive vagal response and into each epicardial fat pad in all groups (p>0.05 between groups.The injections of botulinum toxin demonstrated dramatic prolongation of ERP in all PV-atrial junctions. This effect correlated with less pronounced ERP shortening in response to vagal nerve stimulation. Suppression of AF inducibility was observed at 7 days after endocardial botulinum toxin injections. The level of AF inducibility was: at 7 days – 57% (p<0.001 vs placebo; p<0.001 vs baseline; at 14 days – 61% (p<0.001 vs placebo; p<0.001 vs baseline; at 1 month – 38% (p<0.001 vs placebo; p<0.001 vs baseline; at 3 months – 23% (p = 0.003; p = 0.06 vs baseline. There were no differences between botulinum groups (p>0.05 for all. The effect of AF suppression disappeared at 3 months. No procedure-related complications occurred.Conclusion. Botulinum toxin injection into intramyocardial GPs and epicardial fat pads by an endocardial approach is feasible and safe. It provides complete removal of cardiac vagal responses and reliably reduces vulnerability to atrial fibrillation.

Toxin production in Dinophysis and the fate of these toxins in marine mussels

DEFF Research Database (Denmark)

Nielsen, Lasse Tor

Diarrhetic shellfish poisoning (DSP) poses a considerable threat to food safety and to the economy of shellfish fishers and farmers in many parts of the world. Thousands of DSP intoxications have been reported, and bivalve harvesting can sometimes be closed down several months in a row. The toxins....... acuta. I grew the two species in laboratory cultures at different irradiances (7-130 μmol photons m-2 s-1) and with different food availability. The results showed that irradiance had no effects on toxin profiles, and only limited effects of the cellular toxin contents. Rather, toxin production rates...... are primarily produced by the marine mixotrophic dinoflagellates Dinophysis spp., known to occur in most parts of the world. Dinophysis can, along with other planktonic organisms, be consumed by filter-feeding bivalves, and thus the toxins can accumulate. Dinophysis can produce the three toxin groups, okadaic...

Antioxidant effect of minocycline in gingival epithelium induced by Actinobacillus actinomycetemcomitans serotype B toxin

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Ernie Maduratna Setiawati

2009-03-01

Full Text Available Background: Actinobacillus actinomycetemcomitans (Aa serotype B has been associated with aggressive periodontitis. Gingival epithelial cell is exquisitely sensitive to the toxin and may lead to the epithel protective barrier disruption. Experimental models show that minocycline is not related to it’s antimicrobial effect and protection against neuron cell apoptosis of a number experimental models of brain injury and Parkinson’s disease. Purpose: This study, examined antioxidant effect of minocycline to inhibit apoptosis of gingival epithelium induced crude toxin bacteria Aa serotype B in mice. Methods: Thirty adult mice strain Swiss Webster (balb C were divided randomly into three groups: control group (group A, toxin group (group B and toxin and minocycline group (group C. The mice were taken at 24 hours after application, and then the tissue sections of gingival epithelium were stained with tunnel assay and immunohistochemistry. Result: Treatment with these toxin induced apoptosis of gingival epithelium and was associated with DNA fragmentation and reduced gluthatione (GSH. Minocycline 100 nM significantly increased GSH and reduced apoptosis (p < 0.05. Minocycline provides antioxidant effect against citotoxicity of bacteria Aa serotipe B. Conclusion: Nanomolar concentration of minocycline potential as new therapeutic agent to prevent progressivity of aggressiveness of periodontitis.

Lipid reorganization induced by Shiga toxin clustering on planar membranes.

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Barbara Windschiegl

Full Text Available The homopentameric B-subunit of bacterial protein Shiga toxin (STxB binds to the glycolipid Gb(3 in plasma membranes, which is the initial step for entering cells by a clathrin-independent mechanism. It has been suggested that protein clustering and lipid reorganization determine toxin uptake into cells. Here, we elucidated the molecular requirements for STxB induced Gb(3 clustering and for the proposed lipid reorganization in planar membranes. The influence of binding site III of the B-subunit as well as the Gb(3 lipid structure was investigated by means of high resolution methods such as fluorescence and scanning force microscopy. STxB was found to form protein clusters on homogenous 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC/cholesterol/Gb(3 (65:30:5 bilayers. In contrast, membranes composed of DOPC/cholesterol/sphingomyelin/Gb(3 (40:35:20:5 phase separate into a liquid ordered and liquid disordered phase. Dependent on the fatty acid composition of Gb(3, STxB-Gb(3 complexes organize within the liquid ordered phase upon protein binding. Our findings suggest that STxB is capable of forming a new membrane phase that is characterized by lipid compaction. The significance of this finding is discussed in the context of Shiga toxin-induced formation of endocytic membrane invaginations.

Collaborative Research Program on Seafood Toxins

Science.gov (United States)

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

Alternaria toxin-induced resistance in rose plants against rose aphid (Macrosiphum rosivorum): effect of tenuazonic acid.

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Yang, Fa-zhong; Yang, Bin; Li, Bei-bei; Xiao, Chun

2015-04-01

Many different types of toxins are produced by the fungus, Alternaria alternata (Fr.) Keissler. Little is known, however, regarding the influence of these toxins on insects. In this study, we investigated the toxin-induced inhibitory effects of the toxin produced by A. alternata on the rose aphid, Macrosiphum rosivorum, when the toxin was applied to leaves of the rose, Rosa chinensis. The results demonstrated that the purified crude toxin was non-harmful to rose plants and rose aphids, but had an intensive inhibitory effect on the multiplication of aphids. The inhibitory index against rose aphids reached 87.99% when rose plants were sprayed with the toxin solution at a low concentration. Further results from bioassays with aphids and high performance liquid chromatography (HPLC) analyses demonstrated that tenuazonic acid (TeA) was one of the most important resistance-related active components in the crude toxin. The content of TeA was 0.1199% in the crude toxin under the HPLC method. Similar to the crude toxin, the inhibitory index of pure TeA reached 83.60% 15 d after the rose plants were sprayed with pure TeA solution at the lower concentration of 0.060 μg/ml, while the contents of residual TeA on the surface and in the inner portion of the rose plants were only 0.04 and 0.00 ng/g fresh weight of TeA-treated rose twigs, respectively, 7 d after the treatment. Our results show that TeA, an active component in the A. alternata toxin, can induce the indirect plant-mediated responses in rose plants to intensively enhance the plant's resistances against rose aphids, and the results are very helpful to understand the plant-mediated interaction between fungi and insects on their shared host plants.

Hierarchical Bayesian Modeling of Fluid-Induced Seismicity

Science.gov (United States)

Broccardo, M.; Mignan, A.; Wiemer, S.; Stojadinovic, B.; Giardini, D.

2017-11-01

In this study, we present a Bayesian hierarchical framework to model fluid-induced seismicity. The framework is based on a nonhomogeneous Poisson process with a fluid-induced seismicity rate proportional to the rate of injected fluid. The fluid-induced seismicity rate model depends upon a set of physically meaningful parameters and has been validated for six fluid-induced case studies. In line with the vision of hierarchical Bayesian modeling, the rate parameters are considered as random variables. We develop both the Bayesian inference and updating rules, which are used to develop a probabilistic forecasting model. We tested the Basel 2006 fluid-induced seismic case study to prove that the hierarchical Bayesian model offers a suitable framework to coherently encode both epistemic uncertainty and aleatory variability. Moreover, it provides a robust and consistent short-term seismic forecasting model suitable for online risk quantification and mitigation.

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

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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.

IFN-gamma-induced chemokines synergize with pertussis toxin to promote T cell entry to the central nervous system

DEFF Research Database (Denmark)

Millward, Jason M; Caruso, Maria; Campbell, Iain L

2007-01-01

Inflammation of the CNS, which occurs during multiple sclerosis and experimental autoimmune encephalomyelitis, is characterized by increased levels of IFN-gamma, a cytokine not normally expressed in the CNS. To investigate the role of IFN-gamma in CNS, we used intrathecal injection of a replication......-defective adenovirus encoding murine IFN-gamma (AdIFNgamma) to IFN-gamma-deficient (GKO) mice. This method resulted in stable, long-lived expression of IFN-gamma that could be detected in cerebrospinal fluid using ELISA and Luminex bead immunoassay. IFN-gamma induced expression in the CNS of message and protein...... was predominantly localized to meningeal and ependymal cells, and was also seen in astrocytes and microglia. IFN-gamma-induced chemokine expression did not lead to inflammation. However, when pertussis toxin was given i.p. to mice infected with the IFN-gamma vector, there was a dramatic increase in the number of T...

Rotavirus 2/6 Viruslike Particles Administered Intranasally with Cholera Toxin, Escherichia coli Heat-Labile Toxin (LT), and LT-R192G Induce Protection from Rotavirus Challenge

OpenAIRE

O’Neal, Christine M.; Clements, John D.; Estes, Mary K.; Conner, Margaret E.

1998-01-01

We have shown that rotavirus 2/6 viruslike particles composed of proteins VP2 and VP6 (2/6-VLPs) administered to mice intranasally with cholera toxin (CT) induced protection from rotavirus challenge, as measured by virus shedding. Since it is unclear if CT will be approved for human use, we evaluated the adjuvanticity of Escherichia coli heat-labile toxin (LT) and LT-R192G. Mice were inoculated intranasally with 10 μg of 2/6-VLPs combined with CT, LT, or LT-R192G. All three adjuvants induced ...

Down-regulation of ATF2 in the inhibition of T-2-toxin-induced chondrocyte apoptosis by selenium chondroitin sulfate nanoparticles

Science.gov (United States)

Han, Jing; Guo, Xiong

2013-12-01

Selenium chondroitin sulfate nanoparticles (SeCS) with a size range of 30-200 nm were obtained in our previous study. Meanwhile, the up-regulated expression of ATF2 mRNA and protein levels could be observed in the cartilage from Kashin-Beck disease (KBD) patients. In this paper, we investigated the inhibition effect of SeCS on T-2-toxin-induced apoptosis of chondrocyte from KBD patients. Here, we found that when the chondrocytes were treated with T-2 toxin, the chondrocyte apoptosis performed in a concentration-dependent manner. The apoptosis of chondrocyte induced by T-2 toxin involved the increased levels of ATF2, JNK and p38 mRNAs and related protein expression. SeCS could partly block the T-2-toxin-induced chondrocyte apoptosis by decreasing the expression of ATF2, JNK and p38 mRNAs and p-JNK, p-38, ATF2 and p-ATF2 proteins. JNK and p38 pathways involved in the apoptosis of chondrocyte induced by T-2 toxin, and SeCS was efficient in the inhibition of chondrocyte apoptosis by T-2 toxin. These results suggested that SeCS had a potential for further prevention and treatment for KBD as well as other selenium deficiency disease.

Design of Accumulators and Liquid/Gas Charging of Single Phase Mechanically Pumped Fluid Loop Heat Rejection Systems

Science.gov (United States)

Bhandari, Pradeep; Dudik, Brenda; Birur, Gajanana; Karlmann, Paul; Bame, David; Mastropietro, A. J.

2012-01-01

For single phase mechanically pumped fluid loops used for thermal control of spacecraft, a gas charged accumulator is typically used to modulate pressures within the loop. This is needed to accommodate changes in the working fluid volume due to changes in the operating temperatures as the spacecraft encounters varying thermal environments during its mission. Overall, the three key requirements on the accumulator to maintain an appropriate pressure range throughout the mission are: accommodation of the volume change of the fluid due to temperature changes, avoidance of pump cavitation and prevention of boiling in the liquid. The sizing and design of such an accumulator requires very careful and accurate accounting of temperature distribution within each element of the working fluid for the entire range of conditions expected, accurate knowledge of volume of each fluid element, assessment of corresponding pressures needed to avoid boiling in the liquid, as well as the pressures needed to avoid cavitation in the pump. The appropriate liquid and accumulator strokes required to accommodate the liquid volume change, as well as the appropriate gas volumes, require proper sizing to ensure that the correct pressure range is maintained during the mission. Additionally, a very careful assessment of the process for charging both the gas side and the liquid side of the accumulator is required to properly position the bellows and pressurize the system to a level commensurate with requirements. To achieve the accurate sizing of the accumulator and the charging of the system, sophisticated EXCEL based spreadsheets were developed to rapidly come up with an accumulator design and the corresponding charging parameters. These spreadsheets have proven to be computationally fast and accurate tools for this purpose. This paper will describe the entire process of designing and charging the system, using a case study of the Mars Science Laboratory (MSL) fluid loops, which is en route to

The protective activity of tea against infection by Vibrio cholerae O1.

Science.gov (United States)

Toda, M; Okubo, S; Ikigai, H; Suzuki, T; Suzuki, Y; Shimamura, T

1991-02-01

Extracts of black tea exhibited bactericidal activity against Vibrio cholerae O1. The tea extract inhibited the haemolysin activity of V. cholerae O1, El Tor and the morphological changes of Chinese hamster ovary cells induced by cholera toxin. Tea extract also reduced fluid accumulation induced by cholera toxin in sealed adult mice and by V. cholerae O1 in ligated intestinal loops of rabbits. These findings suggest that tea has protective activity against V. cholerae O1.

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.

Science.gov (United States)

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

Bioterrorism: toxins as weapons.

Science.gov (United States)

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.

Recent Insights into Clostridium perfringens Beta-Toxin

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Masahiro Nagahama

2015-02-01

Full Text Available Clostridium perfringens beta-toxin is a key mediator of necrotizing enterocolitis and enterotoxemia. It is a pore-forming toxin (PFT that exerts cytotoxic effect. Experimental investigation using piglet and rabbit intestinal loop models and a mouse infection model apparently showed that beta-toxin is the important pathogenic factor of the organisms. The toxin caused the swelling and disruption of HL-60 cells and formed a functional pore in the lipid raft microdomains of sensitive cells. These findings represent significant progress in the characterization of the toxin with knowledge on its biological features, mechanism of action and structure-function having been accumulated. Our aims here are to review the current progresses in our comprehension of the virulence of C. perfringens type C and the character, biological feature and structure-function of beta-toxin.

Creatinine concentrations of accumulated intrauterine fluid to confirm the clinical diagnosis of urometra in mares.

Science.gov (United States)

Schnobrich, M R; Gordon, D L; Scoggin, C F; Bradecamp, E A; Canisso, I F

2017-03-25

Urine pooling, as a persistent condition, is a cause of infertility in mares due to endometrial inflammation and sperm toxicity. Identification of urometra can be challenging in mares presenting with the condition intermittently, or when urine flows into the uterus but is undetectable in the vagina. Currently, there are no reported objective methods to confirm the clinical diagnosis of urine contamination in intrauterine-fluid accumulations. Since creatinine is present in high concentrations in urine and does not diffuse across cell membranes, creatinine concentration should be increased in mares with urometra, but negligible in normal and mares with intrauterine fluid accumulation (non-urometra cases). To test this hypothesis, creatinine concentrations of intrauterine fluid were measured in mares with a clinical diagnosis of urine accumulation (n=9) or intrauterine fluid containing no urine (n=10). Results showed that creatinine concentrations (mg/dl) were significantly higher in mares that had a clinical diagnosis of urometra (42.8±12.6, range 4.1-109.2) compared with those that did not (0.38±0.1, range 0-0.9). Also, two mares after urethral extension surgery demonstrated a remarkable reduction in creatinine concentrations. This study highlights an undocumented approach to confirm a clinical diagnosis of urometra in mares; the authors anticipate that testing for creatinine in the uterine fluid of mares may become a standard tool for identifying urometra in mares and confirming the success of urogenital surgeries. British Veterinary Association.

Occlusion therapy of unilateral amblyopia with botulinum toxin induced ptosis.

Science.gov (United States)

Halkiadakis, Ioannis; Iliaki, Olga; Kalyvianaki, Maria I; Tsilimbaris, Miltiadis K

2007-01-01

In order to evaluate the role of botulinum toxin induced ptosis as an occlusion method to treat unilateral deep strabismic amblyopia in two uncooperative children, we injected 0.2 ml of diluted botulinum toxin in the levator palpaebrae; low sedation was necessary in one of the two children. In both cases a marked ptosis was achieved, which lasted about four weeks and then gradually resolved completely. The visual acuity of the ablyopic eye increased in both children, making patching easy thereafter. One child developed amblyopia in the injected eye, which was handled successfully using part-time occlusion. No other side effects were noted. Whether this new method could be a simple, safe and effective alternative method of occlusion for the treatment of deep amblyopia in uncooperative children needs to be proven with a larger series of children.

Occurrence and sequestration of toxins in food chains.

Science.gov (United States)

Mebs, D

1998-11-01

Animals may acquire toxicity by absorbing toxic compounds from their food, e.g. from plants or other animals. Sequestration and accumulation of toxins may provide protection from predators, which learn to avoid this prey because of unpleasant experiences such as bitter taste. This is a common phenomenon in marine as well as in terrestrial ecosystems. Moreover, toxins may enter food chains where they accumulate reaching high, often lethal concentrations. Palytoxin which had been primarily detected in marine zoanthids (Palythoa sp.), occurs also in a wide range of other animals, e.g. in sponges, corals, shellfish, polychaetes and crustaceans, but also in fish, which feed on crustaceans and zoanthids as well. These animals exhibit a high resistance to the toxin's action. The mechanisms which protect the Na+, K+-ATPase of their cell membranes, the primary target of palytoxin, is unknown. Sequestration of the toxin by other animals may cause health problems due to food poisoning.

Radiolabelling of cholera toxin

International Nuclear Information System (INIS)

Santos, R.G.; Neves, Nicoli M.J.; Abdalla, L.F.; Brandao, R.L.; Etchehebehere, L.; Lima, M.E. de; Nicoli, J.R.

1999-01-01

Binding of cholera toxin to ganglioside receptors of enterocyte microvilli catalyzes the activation of adenylate cyclase causing a rise in cAMP which final result is a copious diarrhea. Saccharomyces boulardii, a nonpathogenic yeast has been used to prevent diarrhea. Although the antidiarrheic properties of S. boulardii are widely recognized, this yeast has been used on empirical basis, and the mechanism of this protective effect is unknown. The addition of cholera toxin to S. boulardii induces the raising of cAMP that triggers the activation of neutral trehalase. This suggests that toxin specifically binding to cells, is internalized and active the protein phosphorylation cascade. Our objective is labeling the cholera toxin to verify the presence of binding sites on yeast cell surfaces for the cholera toxin. Cholera toxin was radiolabelled with Na 125 I by a chloramine-T method modified from Cuatrecasas and Griffiths et alii. The 125 I-Cholera toxin showed a specific radioactivity at about 1000 cpm/fmol toxin. Biological activity of labeled cholera toxin measured by trehalase activation was similar to the native toxin. (author)

Effect of Botulinum Toxin Type A on TGF-β/Smad Pathway Signaling: Implications for Silicone-Induced Capsule Formation.

Science.gov (United States)

Kim, Sena; Ahn, Moonsang; Piao, Yibo; Ha, Yooseok; Choi, Dae-Kyoung; Yi, Min-Hee; Shin, Nara; Kim, Dong Woon; Oh, Sang-Ha

2016-11-01

One of the most serious complications of breast surgery using implants is capsular contracture. Several preventive treatments have been introduced; however, the mechanism of capsule formation has not been resolved completely. The authors previously identified negative effects of botulinum toxin type A on capsule formation, expression of transforming growth factor (TGF)-β1, and differentiation of fibroblasts into myofibroblasts. Thus, the authors investigated how to prevent capsule formation by using botulinum toxin type A, particularly by means of TGF-β1 signaling, in human fibroblasts. In vitro, cultured human fibroblasts were treated with TGF-β1 and/or botulinum toxin type A. Expression of collagen, matrix metalloproteinase, and Smad was examined by Western blotting. The activation of matrix metalloproteinase was observed by gelatin zymography. In vivo, the effect of botulinum toxin type A on the phosphorylation of Smad2 in silicone-induced capsule formation was evaluated by immunocytochemistry. In vitro, the phosphorylation of Smad2 was inhibited by botulinum toxin type A treatment. The expression levels of collagen types 1 and 3 were inhibited by botulinum toxin type A treatment, whereas those of matrix metalloproteinase-2 and matrix metalloproteinase-9 were enhanced. Gelatin zymography experiments confirmed enhanced matrix metalloproteinase-2 activity in collagen degradation. In vivo, botulinum toxin type A treatment reduced capsule thickness and Smad2 phosphorylation in silicone-induced capsules. This study suggests that botulinum toxin type A plays an important role in the inhibition of capsule formation through the TGF-β/Smad signaling pathway. Therapeutic, V.

Mechanisms of pertussis toxin-induced barrier dysfunction in bovine pulmonary artery endothelial cell monolayers.

Science.gov (United States)

Patterson, C E; Stasek, J E; Schaphorst, K L; Davis, H W; Garcia, J G

1995-06-01

We have previously characterized several G proteins in endothelial cells (EC) as substrates for the ADP-ribosyltransferase activity of both pertussis (PT) and cholera toxin and described the modulation of key EC physiological responses, including gap formation and barrier function, by these toxins. In this study, we investigated the mechanisms involved in PT-mediated regulation of bovine pulmonary artery endothelial cells barrier function. PT caused a dose-dependent increase in albumin transfer, dependent upon action of the holotoxin, since neither the heat-inactivated PT, the isolated oligomer, nor the protomer induced EC permeability. PT-induced gap formation and barrier dysfunction were additive to either thrombin- or thrombin receptor-activating peptide-induced permeability, suggesting that thrombin and PT utilize distinct mechanisms. PT did not result in Ca2+ mobilization or alter either basal or thrombin-induced myosin light chain phosphorylation. However, PT stimulated protein kinase C (PKC) activation, and both PKC downregulation and PKC inhibition attenuated PT-induced permeability, indicating that PKC activity is involved in PT-induced barrier dysfunction. Like thrombin-induced permeability, the PT effect was blocked by prior increases in adenosine 3',5'-cyclic monophosphate. Thus PT-catalyzed ADP-ribosylation of a G protein (possibly other than Gi) may regulate cytoskeletal protein interactions, leading to EC barrier dysfunction.

Snake venom toxin from vipera lebetina turanica induces apoptosis of colon cancer cells via upregulation of ROS- and JNK-mediated death receptor expression

International Nuclear Information System (INIS)

Park, Mi Hee; Jo, MiRan; Won, Dohee; Song, Ho Sueb; Han, Sang Bae; Song, Min Jong; Hong, Jin Tae

2012-01-01

Abundant research suggested that the cancer cells avoid destruction by the immune system through down-regulation or mutation of death receptors. Therefore, it is very important that finding the agents that increase the death receptors of cancer cells. In this study, we demonstrated that the snake venom toxin from Vipera lebetina turanica induce the apoptosis of colon cancer cells through reactive oxygen species (ROS) and c-Jun N-terminal kinases (JNK) dependent death receptor (DR4 and DR5) expression. We used cell viability assays, DAPI/TUNEL assays, as well as western blot for detection of apoptosis related proteins and DRs to demonstrate that snake venom toxin-induced apoptosis is DR4 and DR5 dependent. We carried out transient siRNA knockdowns of DR4 and DR5 in colon cancer cells. We showed that snake venom toxin inhibited growth of colon cancer cells through induction of apoptosis. We also showed that the expression of DR4 and DR5 was increased by treatment of snake venom toxin. Moreover, knockdown of DR4 or DR5 reversed the effect of snake venom toxin. Snake venom toxin also induced JNK phosphorylation and ROS generation, however, pretreatment of JNK inhibitor and ROS scavenger reversed the inhibitory effect of snake venom toxin on cancer cell proliferation, and reduced the snake venom toxin-induced upregulation of DR4 and DR5 expression. Our results indicated that snake venom toxin could inhibit human colon cancer cell growth, and these effects may be related to ROS and JNK mediated activation of death receptor (DR4 and DR5) signals

Radiolabelling of cholera toxin

Energy Technology Data Exchange (ETDEWEB)

Santos, R.G.; Neves, Nicoli M.J. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil); Abdalla, L.F.; Brandao, R.L.; Etchehebehere, L. [Ouro Preto Univ., MG (Brazil). Escola de Farmacia. Lab. de Fisiologia e Bioquimica de Microorganismos; Lima, M.E. de [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Inst. de Ciencias Biologicas. Dept. de Bioquimica e Imunologia; Nicoli, J.R. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Inst. de Ciencias Biologicas. Dept. de Microbiologia

1999-11-01

Binding of cholera toxin to ganglioside receptors of enterocyte microvilli catalyzes the activation of adenylate cyclase causing a rise in cAMP which final result is a copious diarrhea. Saccharomyces boulardii, a nonpathogenic yeast has been used to prevent diarrhea. Although the antidiarrheic properties of S. boulardii are widely recognized, this yeast has been used on empirical basis, and the mechanism of this protective effect is unknown. The addition of cholera toxin to S. boulardii induces the raising of cAMP that triggers the activation of neutral trehalase. This suggests that toxin specifically binding to cells, is internalized and active the protein phosphorylation cascade. Our objective is labeling the cholera toxin to verify the presence of binding sites on yeast cell surfaces for the cholera toxin. Cholera toxin was radiolabelled with Na {sup 125} I by a chloramine-T method modified from Cuatrecasas and Griffiths et alii. The {sup 125} I-Cholera toxin showed a specific radioactivity at about 1000 cpm/fmol toxin. Biological activity of labeled cholera toxin measured by trehalase activation was similar to the native toxin. (author) 5 refs., 3 figs.; e-mail: nevesmj at urano.cdtn.br

Fluid injection and induced seismicity

Science.gov (United States)

Kendall, Michael; Verdon, James

2016-04-01

The link between fluid injection, or extraction, and induced seismicity has been observed in reservoirs for many decades. In fact spatial mapping of low magnitude events is routinely used to estimate a stimulated reservoir volume. However, the link between subsurface fluid injection and larger felt seismicity is less clear and has attracted recent interest with a dramatic increase in earthquakes associated with the disposal of oilfield waste fluids. In a few cases, hydraulic fracturing has also been linked to induced seismicity. Much can be learned from past case-studies of induced seismicity so that we can better understand the risks posed. Here we examine 12 case examples and consider in particular controls on maximum event size, lateral event distributions, and event depths. Our results suggest that injection volume is a better control on maximum magnitude than past, natural seismicity in a region. This might, however, simply reflect the lack of baseline monitoring and/or long-term seismic records in certain regions. To address this in the UK, the British Geological Survey is leading the deployment of monitoring arrays in prospective shale gas areas in Lancashire and Yorkshire. In most cases, seismicity is generally located in close vicinity to the injection site. However, in some cases, the nearest events are up to 5km from the injection point. This gives an indication of the minimum radius of influence of such fluid injection projects. The most distant events are never more than 20km from the injection point, perhaps implying a maximum radius of influence. Some events are located in the target reservoir, but most occur below the injection depth. In fact, most events lie in the crystalline basement underlying the sedimentary rocks. This suggests that induced seismicity may not pose a leakage risk for fluid migration back to the surface, as it does not impact caprock integrity. A useful application for microseismic data is to try and forecast induced seismicity

Susceptibility of Phelipanche and Orobanche species to AAL-toxin.

Science.gov (United States)

de Zélicourt, Axel; Montiel, Grégory; Pouvreau, Jean-Bernard; Thoiron, Séverine; Delgrange, Sabine; Simier, Philippe; Delavault, Philippe

2009-10-01

Fusarium and Alternaria spp. are phytopathogenic fungi which are known to be virulent on broomrapes and to produce sphinganine-analog mycotoxins (SAMs). AAL-toxin is a SAM produced by Alternaria alternata which causes the inhibition of sphinganine N-acyltransferase, a key enzyme in sphingolipid biosynthesis, leading to accumulation of sphingoid bases. These long chain bases (LCBs) are determinant in the occurrence of programmed cell death (PCD) in susceptible plants. We showed that broomrapes are sensitive to AAL-toxin, which is not common plant behavior, and that AAL-toxin triggers cell death at the apex of the radicle as well as LCB accumulation and DNA laddering. We also demonstrated that three Lag1 homologs, encoding components of sphinganine N-acyltransferase in yeast, are present in the Orobanche cumana genome and two of them are mutated leading to an enhanced susceptibility to AAL-toxin. We therefore propose a model for the molecular mechanism governing broomrape susceptibility to the fungus Alternaria alternata.

Antagonism of botulinum toxin-induced muscle weakness by aminopyridines in rat phrenic nerve-hemidiaphragm preparations

Energy Technology Data Exchange (ETDEWEB)

Adler, M.; Scovill, J.; Deshpande, S.S.

1993-05-13

The effects of the potassium channel inhibitor and putative botulinum toxin antagonists 4-aminopyridine (4-AP) and 3,4-diaminopyridine (3,4-DAP) were investigated in vitro on the contractile and electrophysiological properties of rat diaphragm muscle. In the presence of 300 pM botulinum toxin A (BoTx A), twitches elicited by supramaximal nerve stimulation (0. 1 Hz) were reduced by over 80% in 3 hr. The time to block decreased with increases in temperature, toxin concentration and stimulation frequency. Addition of 4-AP or 3,4-DAP led to a prompt reversal of the BoTx A-induced depression of twitch tension. This reversal was concentration-dependent such that, in the presence of 1 mM 4-AP, reversal of the BoTx A-induced blockade was complete in 6.7 min. The beneficial effect of the APs were well maintained and persisted for up to 6 hr after addition. Application of 1 microns M neostigmine 1 hr after 3,4-DAP produced a further potentiation of twitch tensions, but this action lasted for < 5 min and led to the appearance of tetanic fade during repetitive stimulation. It is concluded that the APs are of benefit in antagonizing the muscle paralysis following exposure to botulinum toxin. Co-application of neostigmine, however, appears to confer no additional benefit.

Food safety: developement of new methods for marine algal toxins detection

OpenAIRE

Barreras Garcia, Alvaro

2013-01-01

2011/2012 SUMMARY Biotoxins produced by harmful algae during their proliferation can be accumulated by filter feeding organisms, such as bivalve shellfish, within their flesh. Furthermore, these toxins gradually are transferred to the higher trophic levels in the food chain, posing a threat to human health, after consumption of contaminated seafood. Filter-feeding invertebrates are organisms in which the toxin accumulation is a well-known phenomenon, especially during harmful algal...

Toxin synergism in snake venoms

DEFF Research Database (Denmark)

Laustsen, Andreas Hougaard

2016-01-01

Synergism between venom toxins exists for a range of snake species. Synergism can be derived from both intermolecular interactions and supramolecular interactions between venom components, and can be the result of toxins targeting the same protein, biochemical pathway or physiological process. Few...... simple systematic tools and methods for determining the presence of synergism exist, but include co-administration of venom components and assessment of Accumulated Toxicity Scores. A better understanding of how to investigate synergism in snake venoms may help unravel strategies for developing novel...

Chemical warfare agent and biological toxin-induced pulmonary toxicity: could stem cells provide potential therapies?

Science.gov (United States)

Angelini, Daniel J; Dorsey, Russell M; Willis, Kristen L; Hong, Charles; Moyer, Robert A; Oyler, Jonathan; Jensen, Neil S; Salem, Harry

2013-01-01

Chemical warfare agents (CWAs) as well as biological toxins present a significant inhalation injury risk to both deployed warfighters and civilian targets of terrorist attacks. Inhalation of many CWAs and biological toxins can induce severe pulmonary toxicity leading to the development of acute lung injury (ALI) as well as acute respiratory distress syndrome (ARDS). The therapeutic options currently used to treat these conditions are very limited and mortality rates remain high. Recent evidence suggests that human stem cells may provide significant therapeutic options for ALI and ARDS in the near future. The threat posed by CWAs and biological toxins for both civilian populations and military personnel is growing, thus understanding the mechanisms of toxicity and potential therapies is critical. This review will outline the pulmonary toxic effects of some of the most common CWAs and biological toxins as well as the potential role of stem cells in treating these types of toxic lung injuries.

The role of fluid migration system in hydrocarbon accumulation in Maichen Sag, Beibuwan Basin

Science.gov (United States)

Liu, Hongyu; Yang, Jinxiu; Wu, Feng; Chen, Wei; Liu, Qianqian

2018-02-01

Fluid migration system is of great significance for hydrocarbon accumulation, including the primary migration and secondary migration. In this paper, the fluid migration system is analysed in Maichen Sag using seismic, well logging and core data. Results show that many factors control the hydrocarbon migration process, including hydrocarbon generation and expulsion period from source rocks, microfractures developed in the source rocks, the connected permeable sand bodies, the vertical faults cutting into/through the source rocks and related fault activity period. The spatial and temporal combination of these factors formed an effective network for hydrocarbon expulsion and accumulation, leading to the hydrocarbon reservoir distribution at present. Generally, a better understanding of the hydrocarbon migration system can explain the present status of hydrocarbon distribution, and help select future target zones for oil and gas exploration.

Cephalopods as Vectors of Harmful Algal Bloom Toxins in Marine Food Webs

Directory of Open Access Journals (Sweden)

Rui Rosa

2013-09-01

Full Text Available Here we summarize the current knowledge on the transfer and accumulation of harmful algal bloom (HAB-related toxins in cephalopods (octopods, cuttlefishes and squids. These mollusks have been reported to accumulate several HAB-toxins, namely domoic acid (DA, and its isomers, saxitoxin (and its derivatives and palytoxin (and palytoxin-like compounds and, therefore, act as HAB-toxin vectors in marine food webs. Coastal octopods and cuttlefishes store considerably high levels of DA (amnesic shellfish toxin in several tissues, but mainly in the digestive gland (DG—the primary site of digestive absorption and intracellular digestion. Studies on the sub-cellular partitioning of DA in the soluble and insoluble fractions showed that nearly all DA (92.6% is found in the cytosol. This favors the trophic transfer of the toxins since cytosolic substances can be absorbed by predators with greater efficiency. The available information on the accumulation and tissue distribution of DA in squids (e.g., in stranded Humboldt squids, Dosidicus gigas is scarcer than in other cephalopod groups. Regarding paralytic shellfish toxins (PSTs, these organisms accumulate them at the greatest extent in DG >> kidneys > stomach > branchial hearts > posterior salivary glands > gills. Palytoxins are among the most toxic molecules identified and stranded octopods revealed high contamination levels, with ovatoxin (a palytoxin analogue reaching 971 μg kg−1 and palytoxin reaching 115 μg kg−1 (the regulatory limit for PlTXs is 30 μg kg−1 in shellfish. Although the impacts of HAB-toxins in cephalopod physiology are not as well understood as in fish species, similar effects are expected since they possess a complex nervous system and highly developed brain comparable to that of the vertebrates. Compared to bivalves, cephalopods represent a lower risk of shellfish poisoning in humans, since they are usually consumed eviscerated, with exception of traditional dishes from the

[Botulism: structure and function of botulinum toxin and its clinical application].

Science.gov (United States)

Oguma, Keiji; Yamamoto, Yumiko; Suzuki, Tomonori; Fatmawati, Ni Nengah Dwi; Fujita, Kumiko

2012-08-01

Clostridium botulinum produces seven immunological distinct poisonous neurotoxins, A to G, with molecular masses of approximately 150kDa. In acidic foods and culture fluid, the neurotoxins associate with non-toxic components, and form large complexes designated progenitor toxins. The progenitor toxins are found in three forms named LL, L, and M. These neurotoxins and progenitor toxins were purified, and whole nucleotide sequences of their structure genes were determined. In this manuscript, the structure and function of these toxins, and the application of these toxins to clinical usage have been described.

Botulinum toxin

Directory of Open Access Journals (Sweden)

Nigam P

2010-01-01

Full Text Available Botulinum toxin, one of the most poisonous biological substances known, is a neurotoxin produced by the bacterium Clostridium botulinum. C. botulinum elaborates eight antigenically distinguishable exotoxins (A, B, C 1 , C 2 , D, E, F and G. All serotypes interfere with neural transmission by blocking the release of acetylcholine, the principal neurotransmitter at the neuromuscular junction, causing muscle paralysis. The weakness induced by injection with botulinum toxin A usually lasts about three months. Botulinum toxins now play a very significant role in the management of a wide variety of medical conditions, especially strabismus and focal dystonias, hemifacial spasm, and various spastic movement disorders, headaches, hypersalivation, hyperhidrosis, and some chronic conditions that respond only partially to medical treatment. The list of possible new indications is rapidly expanding. The cosmetological applications include correction of lines, creases and wrinkling all over the face, chin, neck, and chest to dermatological applications such as hyperhidrosis. Injections with botulinum toxin are generally well tolerated and side effects are few. A precise knowledge and understanding of the functional anatomy of the mimetic muscles is absolutely necessary to correctly use botulinum toxins in clinical practice.

Anthrax lethal toxin inhibits translation of hypoxia-inducible factor 1α and causes decreased tolerance to hypoxic stress.

Science.gov (United States)

Ouyang, Weiming; Torigoe, Chikako; Fang, Hui; Xie, Tao; Frucht, David M

2014-02-14

Hypoxia is considered to be a contributor to the pathology associated with administration of anthrax lethal toxin (LT). However, we report here that serum lactate levels in LT-treated mice are reduced, a finding inconsistent with the anaerobic metabolism expected to occur during hypoxia. Reduced lactate levels are also observed in the culture supernatants of LT-treated cells. LT inhibits the accumulation of hypoxia-inducible factor (HIF)-1α, a subunit of HIF-1, the master regulator directing cellular responses to hypoxia. The toxin has no effect on the transcription or protein turnover of HIF-1α, but instead it acts to inhibit HIF-1α translation. LT treatment diminishes phosphorylation of eIF4B, eIF4E, and rpS6, critical components of the intracellular machinery required for HIF-1α translation. Moreover, blockade of MKK1/2-ERK1/2, but not p38 or JNK signaling, lowers HIF-1α protein levels in both normoxic and hypoxic conditions, consistent with a role for MKK1 and MKK2 as the major targets of LT responsible for the inhibition of HIF-1α translation. The physiological importance of the LT-induced translation blockade is demonstrated by the finding that LT treatment decreases the survival of hepatocyte cell lines grown in hypoxic conditions, an effect that is overcome by preinduction of HIF-1α. Taken together, these data support a role for LT in dysregulating HIF-1α and thereby disrupting homeostatic responses to hypoxia, an environmental characteristic of certain tissues at baseline and/or during disseminated infection with Bacillus anthracis.

YghJ, the secreted metalloprotease of pathogenic E. coli induces hemorrhagic fluid accumulation in mouse ileal loop.

Science.gov (United States)

Tapader, Rima; Bose, Dipro; Pal, Amit

2017-04-01

YghJ, also known as SslE (Secreted and surface associated lipoprotein) is a cell surface associated and secreted lipoprotein harbouring M60 metalloprotease domain. Though the gene is known to be conserved among both pathogenic and commensal Escherichia coli isolates, the expression and secretion of YghJ was found to be higher among diverse E. coli pathotypes. YghJ, secreted from intestinal pathogens such as enterotoxigenic E. coli (ETEC) and enteropathogenic E. coli (EPEC) has been demonstrated to possess mucinase activity and hence facilitates colonization of these enteric pathogens to intestinal epithelial cells. Importantly, YghJ is also reported to be secreted from extraintestinal pathogenic E. coli isolates. In our previous study we have shown that YghJ, purified from a neonatal septicemic E. coli isolate could trigger induction of various proinflammatory cytokines in vitro. This led us to investigate the role of YghJ in causing in vivo tissue hemorrhage. In the present study, we validate the earlier in vitro finding and have showed that YghJ can cause extensive tissue damage in mouse ileum and is also able to induce significant fluid accumulation in a dose dependent manner in a mouse ileal loop (MIL) assay. Hence, our present study not only confirms the pathogenic potential of YghJ in sepsis pathophysiology but also indicates the enterotoxic ability of YghJ which makes it an important virulence determinant of intestinal pathogenic E. coli. Copyright © 2017 Elsevier Ltd. All rights reserved.

Intranasal delivery of cholera toxin induces th17-dominated T-cell response to bystander antigens.

Directory of Open Access Journals (Sweden)

Jee-Boong Lee

Full Text Available Cholera toxin (CT is a potent vaccine adjuvant, which promotes mucosal immunity to protein antigen given by nasal route. It has been suggested that CT promotes T helper type 2 (Th2 response and suppresses Th1 response. We here report the induction of Th17-dominated responses in mice by intranasal delivery of CT. This dramatic Th17-driving effect of CT, which was dependent on the B subunit, was observed even in Th1 or Th2-favored conditions of respiratory virus infection. These dominating Th17 responses resulted in the significant neutrophil accumulation in the lungs of mice given CT. Both in vitro and in vivo treatment of CT induced strongly augmented IL-6 production, and Th17-driving ability of CT was completely abolished in IL-6 knockout mice, indicating a role of this cytokine in the Th17-dominated T-cell responses by CT. These data demonstrate a novel Th17-driving activity of CT, and help understand the mechanisms of CT adjuvanticity to demarcate T helper responses.

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

Science.gov (United States)

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.

Treatment of ovarian cancer ascites by intra-peritoneal injection of diphtheria toxin A chain-H19 vector: a case report

Directory of Open Access Journals (Sweden)

Abu-lail Rasha

2010-07-01

Full Text Available Abstract Introduction Ovarian cancer ascitic fluid, which contains malignant cells, is usually present in women with an advanced stage disease. There are currently no effective therapies for the treatment of ovarian cancer ascitic fluid. We developed a new therapeutic strategy to target expression of the diphtheria toxin fragment A gene in ovarian tumor cells under the control of H19 regulatory sequences. Case presentation A 64-year-old Caucasian woman was diagnosed with a stage IIIc epithelial ovarian cancer. She suffered from progressive disease, accumulation of malignant ascites that needed to be drained weekly, abdominal pain, vomiting, anorexia and severe weakness. Infusion of the diphtheria toxin A chain-H19 plasmid into the peritoneum of our patient resulted in complete resolution of the ascites with minimum adverse events. Conclusion On the basis of this preliminary experience, we are currently conducting an extensive Phase I study on a larger number of patients in order to assess the safety and preliminary efficacy of this novel patient-oriented treatment approach.

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

Science.gov (United States)

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.

Cholera toxin-induced ADP-ribosylation of a 46 kDa protein is decreased in brains of ethanol-fed mice

International Nuclear Information System (INIS)

Nhamburo, P.T.; Hoffman, P.L.; Tabakoff, B.

1988-01-01

The acute in vitro effects of ethanol on cerebral cortical adenylate cyclase activity and beta-adrenergic receptor characteristics suggested a site of action of ethanol at Gs, the stimulatory guanine nucleotide binding protein. After chronic ethanol ingestion, the beta-adrenergic receptor appeared to be uncoupled (i.e., the form of the receptor with high affinity for agonist was undetectable), and stimulation of adenylate cyclase activity by isoproterenol or guanine nucleotides was reduced, suggesting an alteration in the properties of Gs. To further characterize this change, cholera and pertussis toxin-mediated 32 P-ADP-ribosylation of mouse cortical membranes was assessed in mice that had chronically ingested ethanol in a liquid diet. 32 P-labeled proteins were separated by SDS-PAGE and quantitated by autoradiography. There was a selective 30-50% decrease in cholera toxin-induced labeling of 46 kDa protein band in membranes of ethanol-fed mice, with no apparent change in pertussis toxin-induced labeling. The 46 kDa protein has a molecular weight similar to that of the alpha subunit of Gs, suggesting a reduced amount of this protein or a change in its characteristics as a substrate for cholera toxin-induced ADP-ribosylation in cortical membranes of ethanol-fed mice

Purinergic signaling is required for fluid shear stress-induced NF-{kappa}B translocation in osteoblasts

Energy Technology Data Exchange (ETDEWEB)

Genetos, Damian C., E-mail: dgenetos@ucdavis.edu [Department of Anatomy, Cell Biology, and Physiology, School of Veterinary Medicine, University of California, Davis, CA (United States); Karin, Norman J. [Cell Biology and Biochemistry, Pacific Northwest National Laboratory, Richland, WA (United States); Geist, Derik J. [Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, IN (United States); Donahue, Henry J. [Division of Musculoskeletal Sciences, Department of Orthopaedics and Rehabilitation, Pennsylvania State College of Medicine, Hershey, PA (United States); Duncan, Randall L. [Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, IN (United States)

2011-04-01

Fluid shear stress regulates gene expression in osteoblasts, in part by activation of the transcription factor NF-{kappa}B. We examined whether this process was under the control of purinoceptor activation. MC3T3-E1 osteoblasts under static conditions expressed the NF-{kappa}B inhibitory protein I{kappa}B{alpha} and exhibited cytosolic localization of NF-{kappa}B. Under fluid shear stress, I{kappa}B{alpha} levels decreased, and concomitant nuclear localization of NF-{kappa}B was observed. Cells exposed to fluid shear stress in ATP-depleted medium exhibited no significant reduction in I{kappa}B{alpha}, and NF-{kappa}B remained within the cytosol. Similar results were found using oxidized ATP or Brilliant Blue G, P2X{sub 7} receptor antagonists, indicating that the P2X{sub 7} receptor is responsible for fluid shear-stress-induced I{kappa}B{alpha} degradation and nuclear accumulation of NF-{kappa}B. Pharmacologic blockage of the P2Y6 receptor also prevented shear-induced I{kappa}B{alpha} degradation. These phenomena involved neither ERK1/2 signaling nor autocrine activation by P2X{sub 7}-generated lysophosphatidic acid. Our results suggest that fluid shear stress regulates NF-{kappa}B activity through the P2Y{sub 6} and P2X{sub 7} receptor.

The cytolethal distending toxin from the chancroid bacterium Haemophilus ducreyi induces cell-cycle arrest in the G2 phase.

Science.gov (United States)

Cortes-Bratti, X; Chaves-Olarte, E; Lagergård, T; Thelestam, M

1999-01-01

The potent cytolethal distending toxin produced by Haemophilus ducreyi is a putative virulence factor in the pathogenesis of chancroid. We studied its action on eukaryotic cells, with the long-term goal of understanding the pathophysiology of the disease. Intoxication of cultured human epithelial-like cells, human keratinocytes, and hamster fibroblasts was irreversible, and appeared as a gradual distention of three- to fivefold the size of control cells. Organized actin assemblies appeared concomitantly with cell enlargement, promoted by a mechanism that probably does not involve small GTPases of the Rho protein family. Intoxicated cells did not proliferate. Similar to cells treated with other cytolethal distending toxins, these cells accumulated in the G2 phase of the cell cycle, demonstrating an increased level of the tyrosine phosphorylated (inactive) form of the cyclin-dependent kinase p34(cdc2). DNA synthesis was not affected until several hours after this increase, suggesting that the toxin acts directly on some kinase/phosphatase in the signaling network controlling the p34(cdc2) activity. We propose that this toxin has an important role both in the generation of chancroid ulcers and in their slow healing. The toxin may also be an interesting new tool for molecular studies of the eukaryotic cell- cycle machinery.

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

Directory of Open Access Journals (Sweden)

Masaya Takehara

2017-08-01

Full Text Available 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.

Salt stress induced ion accumulation, ion homeostasis, membrane ...

African Journals Online (AJOL)

Salt stress induced ion accumulation, ion homeostasis, membrane injury and sugar contents in salt-sensitive rice ( Oryza sativa L. spp. indica ) roots under isoosmotic conditions. ... The accumulation of sugars in PT1 roots may be a primary salt-defense mechanism and may function as an osmotic control. Key words: ...

Ablative fractional laser enhances MAL-induced PpIX accumulation

DEFF Research Database (Denmark)

Haak, C S; Christiansen, K; Erlendsson, Andrés M

2016-01-01

BACKGROUND AND OBJECTIVES: Pretreatment of skin with ablative fractional laser enhances accumulation of topical provided photosensitizer, but essential information is lacking on the interaction between laser channel densities and pharmacokinetics. Hence our objectives were to investigate how...... (range 46-133min) induced fluorescence levels similar to curettage and 180min incubation. Furthermore, MAL 80 and 160mg/g induced similar fluorescence intensities in skin exposed to laser densities of 1, 2 and 5% (p>0.0537, 30-180min). CONCLUSION: MAL-induced protoporphyrin accumulation is augmented...... protoporphyrin accumulation was affected by laser densities, incubation time and drug concentration. METHODS: We conducted the study on the back of healthy male volunteers (n=11). Test areas were pretreated with 2940nm ablative fractional Er:YAG laser, 11.2mJ per laser channel using densities of 1, 2, 5, 10...

Array biosensor for detection of toxins

Science.gov (United States)

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).

Timing, predictors, and progress of third space fluid accumulation during preliminary phase fluid resuscitation in adult patients with dengue.

Science.gov (United States)

Premaratna, R; Ragupathy, A; Miththinda, J K N D; de Silva, H J

2013-07-01

Fluid leakage remains the hallmark of dengue hemorrhagic fever (DHF). The applicability of currently recommended predictors of DHF for adults with dengue is questionable as these are based on studies conducted in children. One hundred and two adults with dengue were prospectively followed up to investigate whether home-based or hospital-based early phase fluid resuscitation has an impact on clinical and hematological parameters used for the diagnosis of early or critical phase fluid leakage. In the majority of subjects, third space fluid accumulation (TSFA) was detected on the fifth and sixth days of infection. The quantity and quality of fluids administered played no role in TSFA. A reduction in systolic blood pressure appeared to be more helpful than a reduction in pulse pressure in predicting fluid leakage. TSFA occurred with lower percentage rises in packed cell volume (PCV) than stated in the current recommendations. A rapid reduction in platelets, progressive reduction in white blood cells, percentage rises in Haemoglobin (Hb), and PCV, and rises in aspartate aminotransferase and alanine aminotransferase were observed in patients with TSFA and therefore with the development of severe illness. Clinicians should be aware of the limitations of currently recommended predictors of DHF in adult patients who are receiving fluid resuscitation. Copyright © 2013 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Characterization of ultraviolet light-induced diphtheria toxin-resistant mutations in normal and Xeroderma pigmentosum human fibroblasts

International Nuclear Information System (INIS)

Glover, T.W.

1979-01-01

Quantitative mutagenesis studies in human cells have been severely limited by the lack of reliable genetic markers. Experiments were therefore performed to develop and characterize a better quantitative mutation assay for human cells. The uv-induction of diphtheria toxin resistant (DT/sup r/) mutations in normal and excision repair defective xeroderma pigmentosum (XP) fibroblasts has been quantitatively characterized. A concentration of diphtheria toxin to use in the selection of resistant mutants was determined whereby DT/sup r/ cells are cross-resistant to Pseudomonas aeurginosa exotoxin A, indicating mutants have altered elongation factor-2 (EF-2) which is not susceptible to ADP-ribosylation by either toxin. Results of this study indicate that XP fibroblasts have higher uv-induced mutation frequencies per unit uv-dose but similar frequencies per unit survival compared to normal cells as measured using a new genetic marker for quantitative mutagenesis. Furthermore, these results support a prediction of the mutation theory of cancer, namely, that cells from individuals with certain human syndromes that predispose the individual to cancer will have higher induced mutation frequencies than cells from non-susceptible individuals. This newly characterized genetic marker should be useful in quantitative mutagenesis studies in human cells

Bicarbonate trigger for inducing lipid accumulation in algal systems

Science.gov (United States)

Gardner, Robert; Peyton, Brent; Cooksey, Keith E.

2015-08-04

The present invention provides bicarbonate containing and/or bicarbonate-producing compositions and methods to induce lipid accumulation in an algae growth system, wherein the algae growth system is under light-dark cycling condition. By adding said compositions at a specific growth stage, said methods lead to much higher lipid accumulation and/or significantly reduced total time required for accumulating lipid in the algae growth system.

Model-based Estimation of Gas Leakage for Fluid Power Accumulators in Wind Turbines

DEFF Research Database (Denmark)

Liniger, Jesper; Pedersen, Henrik Clemmensen; N. Soltani, Mohsen

2017-01-01

for accumulators, namely gas leakage. The method utilizes an Extended Kalman Filter for joint state and parameter estimation with special attention to limiting the use of sensors to those commonly used in wind turbines. The precision of the method is investigated on an experimental setup which allows for operation...... of the accumulator similar to the conditions in a turbine. The results show that gas leakage is indeed detectable during start-up of the turbine and robust behavior is achieved in a multi-fault environment where both gas and external fluid leakage occur simultaneously. The estimation precision is shown...... to be sensitive to initial conditions for the gas temperature and volume....

Cannabidiol restores intestinal barrier dysfunction and inhibits the apoptotic process induced by Clostridium difficile toxin A in Caco-2 cells.

Science.gov (United States)

Gigli, Stefano; Seguella, Luisa; Pesce, Marcella; Bruzzese, Eugenia; D'Alessandro, Alessandra; Cuomo, Rosario; Steardo, Luca; Sarnelli, Giovanni; Esposito, Giuseppe

2017-12-01

Clostridium difficile toxin A is responsible for colonic damage observed in infected patients. Drugs able to restore Clostridium difficile toxin A-induced toxicity have the potential to improve the recovery of infected patients. Cannabidiol is a non-psychotropic component of Cannabis sativa, which has been demonstrated to protect enterocytes against chemical and/or inflammatory damage and to restore intestinal mucosa integrity. The purpose of this study was to evaluate (a) the anti-apoptotic effect and (b) the mechanisms by which cannabidiol protects mucosal integrity in Caco-2 cells exposed to Clostridium difficile toxin A. Caco-2 cells were exposed to Clostridium difficile toxin A (30 ng/ml), with or without cannabidiol (10 -7 -10 -9  M), in the presence of the specific antagonist AM251 (10 -7  M). Cytotoxicity assay, transepithelial electrical resistence measurements, immunofluorescence analysis and immunoblot analysis were performed in the different experimental conditions. Clostridium difficile toxin A significantly decreased Caco-2 cells' viability and reduced transepithelial electrical resistence values and RhoA guanosine triphosphate (GTP), bax, zonula occludens-1 and occludin protein expression, respectively. All these effects were significantly and concentration-dependently inhibited by cannabidiol, whose effects were completely abolished in the presence of the cannabinoid receptor type 1 (CB1) antagonist, AM251. Cannabidiol improved Clostridium difficile toxin A-induced damage in Caco-2 cells, by inhibiting the apoptotic process and restoring the intestinal barrier integrity, through the involvement of the CB1 receptor.

Radiation toxins: molecular mechanisms of action and radiomimetic properties .

Science.gov (United States)

Popov, Dmitri; Maliev, Vecheslav

after high doses of radiation, some specific receptors such as the NMDA receptor and AMP receptor are over activated. Radiation Neurotoxins (specific) could induce activation of neurotransmitters such as glutamate. The toxicity of different types of ionizing radiation is also associated with a formation of specific or essential Radiation Toxins and a group of Radiation Toxins (RT) -Specific Radiation Determinant (SRD). Activity of RT SRD is especially important in develop-ment of the systemic inflammatory response syndrome and patho-physiological processes that are specific for different form of ARS. Materials and Methods: The SRD, a group of Radiation Toxins isolated from lymph of irradiated mammals, had been divided to four important group of toxins: 1.Cerebrovascular neurotoxic RT (SRD-1); 2.Cardiovascular neurotoxic RT(SRD-2); 3.Gastrointestinal neurotoxic RT (SRD-3); 4.Hematotoxic RT (SRD-4). We had performed four experiments with administration (IV or IM) of SRD RT to healthy, radiation naive ani-mals that induced development of clinical symptoms of the ARS. Experiment N1. Injection of SRD-1 in toxic doses to rats, rabbits, sheep. In these experimental animals, a period of extreme agitation was replaced by a deep coma, with breathing and cardiovascular supression. The re-sults of autopsy of their bodies demonstrated cerebral hemorrhagic strokes, cerebrospinal fluid with blood (reddish color), hemorrhagic lesions in brain tissue. Internal organs were filled with blood. Multiple petechiae were observed on serous membranes. Depending on doses of SRD-1, death was registered in 30 min or up to 5 hours after injection. Experiment N2. Injection of SRD-2 in toxic doses to rats, rabbits,sheep. In this experiment, following important symptoms were registered: phase of extreme agitation was shorter, less expressed, and accompanied by cardiac arrhythmia, tachycardia, tachypnea. Results of postmortem section revealed changes in the cardiac muscle tissue. Experiment N3

Workshop on induced Seismicity due to fluid injection/production from Energy-Related Applications

Energy Technology Data Exchange (ETDEWEB)

Majer, E.L.; Asanuma, Hiroshi; Rueter, Horst; Stump, Brian; Segall, Paul; Zoback, Mark; Nelson, Jim; Frohlich, Cliff; Rutledge, Jim; Gritto, Roland; Baria, Roy; Hickman, Steve; McGarr, Art; Ellsworth, Bill; Lockner, Dave; Oppenheimer, David; Henning, Peter; Rosca, Anca; Hornby, Brian; Wang, Herb; Beeler, Nick; Ghassemi, Ahmad; Walters, Mark; Robertson-Tait, Ann; Dracos, Peter; Fehler, Mike; Abou-Sayed, Ahmed; Ake, Jon; Vorobiev, Oleg; Julian, Bruce

2011-04-01

Geothermal energy, carbon sequestration, and enhanced oil and gas recovery have a clear role in U.S. energy policy, both in securing cost-effective energy and reducing atmospheric CO{sub 2} accumulations. Recent publicity surrounding induced seismicity at several geothermal and oil and gas sites points out the need to develop improved standards and practices to avoid issues that may unduly inhibit or stop the above technologies from fulfilling their full potential. It is critical that policy makers and the general community be assured that EGS, CO{sub 2} sequestration, enhanced oil/gas recovery, and other technologies relying on fluid injections, will be designed to reduce induced seismicity to an acceptable level, and be developed in a safe and cost-effective manner. Induced seismicity is not new - it has occurred as part of many different energy and industrial applications (reservoir impoundment, mining, oil recovery, construction, waste disposal, conventional geothermal). With proper study/research and engineering controls, induced seismicity should eventually allow safe and cost-effective implementation of any of these technologies. In addition, microseismicity is now being used as a remote sensing tool for understanding and measuring the success of injecting fluid into the subsurface in a variety of applications, including the enhancement of formation permeability through fracture creation/reactivation, tracking fluid migration and storage, and physics associated with stress redistribution. This potential problem was envisaged in 2004 following observed seismicity at several EGS sites, a study was implemented by DOE to produce a white paper and a protocol (Majer et al 2008) to help potential investors. Recently, however, there have been a significant number of adverse comments by the press regarding induced seismicity which could adversely affect the development of the energy sector in the USA. Therefore, in order to identify critical technology and research

Toxin ζ Reversible Induces Dormancy and Reduces the UDP-N-Acetylglucosamine Pool as One of the Protective Responses to Cope with Stress

Directory of Open Access Journals (Sweden)

Mariangela Tabone

2014-09-01

Full Text Available Toxins of the ζ/PezT family, found in the genome of major human pathogens, phosphorylate the peptidoglycan precursor uridine diphosphate-N-acetylglucosamine (UNAG leading to unreactive UNAG-3P. Transient over-expression of a PezT variant impairs cell wall biosynthesis and triggers autolysis in Escherichia coli. Conversely, physiological levels of ζ reversibly induce dormancy produce a sub-fraction of membrane-compromised cells, and a minor subpopulation of Bacillus subtilis cells become tolerant of toxin action. We report here that purified ζ is a strong UNAG-dependent ATPase, being GTP a lower competitor. In vitro, ζ toxin phosphorylates a fraction of UNAG. In vivo, ζ-mediated inactivation of UNAG by phosphorylation does not deplete the active UNAG pool, because expression of the toxin enhances the efficacy of genuine cell wall inhibitors (fosfomycin, vancomycin or ampicillin. Transient ζ expression together with fosfomycin treatment halt cell proliferation, but ε2 antitoxin expression facilitates the exit of ζ-induced dormancy, suggesting that there is sufficient UNAG for growth. We propose that ζ induces diverse cellular responses to cope with stress, being the reduction of the UNAG pool one among them. If the action of ζ is not inhibited, e.g., by de novo ε2 antitoxin synthesis, the toxin markedly enhances the efficacy of antimicrobial treatment without massive autolysis in Firmicutes.

Fluid transport in reaction induced fractures

Science.gov (United States)

Ulven, Ole Ivar; Sun, WaiChing; Malthe-Sørenssen, Anders

2015-04-01

The process of fracture formation due to a volume increasing chemical reaction has been studied in a variety of different settings, e.g. weathering of dolerites by Røyne et al. te{royne}, serpentinization and carbonation of peridotite by Rudge et al. te{rudge} and replacement reactions in silica-poor igneous rocks by Jamtveit et al. te{jamtveit}. It is generally assumed that fracture formation will increase the net permeability of the rock, and thus increase the reactant transport rate and subsequently the total rate of material conversion, as summarised by Kelemen et al. te{kelemen}. Ulven et al. te{ulven_1} have shown that for fluid-mediated processes the ratio between chemical reaction rate and fluid transport rate in bulk rock controls the fracture pattern formed, and Ulven et al. te{ulven_2} have shown that instantaneous fluid transport in fractures lead to a significant increase in the total rate of the volume expanding process. However, instantaneous fluid transport in fractures is clearly an overestimate, and achievable fluid transport rates in fractures have apparently not been studied in any detail. Fractures cutting through an entire domain might experience relatively fast advective reactant transport, whereas dead-end fractures will be limited to diffusion of reactants in the fluid, internal fluid mixing in the fracture or capillary flow into newly formed fractures. Understanding the feedback process between fracture formation and permeability changes is essential in assessing industrial scale CO2 sequestration in ultramafic rock, but little is seemingly known about how large the permeability change will be in reaction-induced fracturing. In this work, we study the feedback between fracture formation during volume expansion and fluid transport in different fracture settings. We combine a discrete element model (DEM) describing a volume expanding process and the related fracture formation with different models that describe the fluid transport in the

Dinophysis Toxins: Causative Organisms, Distribution and Fate in Shellfish

Science.gov (United States)

Reguera, Beatriz; Riobó, Pilar; Rodríguez, Francisco; Díaz, Patricio A.; Pizarro, Gemita; Paz, Beatriz; Franco, José M.; Blanco, Juan

2014-01-01

Several Dinophysis species produce diarrhoetic toxins (okadaic acid and dinophysistoxins) and pectenotoxins, and cause gastointestinal illness, Diarrhetic Shellfish Poisoning (DSP), even at low cell densities (Chile, and Europe. Toxicity and toxin profiles are very variable, more between strains than species. The distribution of DSP events mirrors that of shellfish production areas that have implemented toxin regulations, otherwise misinterpreted as bacterial or viral contamination. Field observations and laboratory experiments have shown that most of the toxins produced by Dinophysis are released into the medium, raising questions about the ecological role of extracelular toxins and their potential uptake by shellfish. Shellfish contamination results from a complex balance between food selection, adsorption, species-specific enzymatic transformations, and allometric processes. Highest risk areas are those combining Dinophysis strains with high cell content of okadaates, aquaculture with predominance of mytilids (good accumulators of toxins), and consumers who frequently include mussels in their diet. Regions including pectenotoxins in their regulated phycotoxins will suffer from much longer harvesting bans and from disloyal competition with production areas where these toxins have been deregulated. PMID:24447996

Accumulation of cyanobacterial toxins in freshwater "seafood" and its consequences for public health: A review

NARCIS (Netherlands)

Ibelings, B.W.; Chorus, I.

2007-01-01

This review summarizes and discusses the current understanding of human exposure to cyanobacterial toxins in “seafood” collected from freshwater and coastal areas. The review consists of three parts: (a) the existing literature on concentrations of cyanobacterial toxins in seafood is reviewed, and

Uptake, transfer and elimination kinetics of paralytic shellfish toxins in common octopus (Octopus vulgaris).

Science.gov (United States)

Lopes, Vanessa M; Baptista, Miguel; Repolho, Tiago; Rosa, Rui; Costa, Pedro Reis

2014-01-01

Marine phycotoxins derived from harmful algal blooms are known to be associated with mass mortalities in the higher trophic levels of marine food webs. Bivalve mollusks and planktivorous fish are the most studied vectors of marine phycotoxins. However, field surveys recently showed that cephalopod mollusks also constitute potential vectors of toxins. Thus, here we determine, for the first time, the time course of accumulation and depuration of paralytic shellfish toxins (PSTs) in the common octopus (Octopus vulgaris). Concomitantly, the underlying kinetics of toxin transfer between tissue compartments was also calculated. Naturally contaminated clams were used to orally expose the octopus to PSTs during 6 days. Afterwards, octopus specimens were fed with non-contaminated shellfish during 10 days of depuration period. Toxins reached the highest concentrations in the digestive gland surpassing the levels in the kidney by three orders of magnitude. PSTs were not detected in any other tissue analyzed. Net accumulation efficiencies of 42% for GTX5, 36% for dcSTX and 23% for C1+2 were calculated for the digestive gland. These compounds were the most abundant toxins in both digestive gland and the contaminated shellfish diet. The small differences in relative abundance of each toxin observed between the prey and the cephalopod predator indicates low conversion rates of these toxins. The depuration period was better described using an exponential decay model comprising a single compartment - the entire viscera. It is worth noting that since octopuses' excretion and depuration rates are low, the digestive gland is able to accumulate very high toxin concentrations for long periods of time. Therefore, the present study clearly shows that O. vulgaris is a high-potential vector of PSTs during and even after the occurrence of these toxic algal blooms. Copyright © 2013 Elsevier B.V. All rights reserved.

Nucleation speed limit on remote fluid induced earthquakes

Science.gov (United States)

Parsons, Thomas E.; Akinci, Aybige; Malignini, Luca

2017-01-01

Earthquakes triggered by other remote seismic events are explained as a response to long-traveling seismic waves that temporarily stress the crust. However, delays of hours or days after seismic waves pass through are reported by several studies, which are difficult to reconcile with the transient stresses imparted by seismic waves. We show that these delays are proportional to magnitude and that nucleation times are best fit to a fluid diffusion process if the governing rupture process involves unlocking a magnitude-dependent critical nucleation zone. It is well established that distant earthquakes can strongly affect the pressure and distribution of crustal pore fluids. Earth’s crust contains hydraulically isolated, pressurized compartments in which fluids are contained within low-permeability walls. We know that strong shaking induced by seismic waves from large earthquakes can change the permeability of rocks. Thus, the boundary of a pressurized compartment may see its permeability rise. Previously confined, overpressurized pore fluids may then diffuse away, infiltrate faults, decrease their strength, and induce earthquakes. Magnitude-dependent delays and critical nucleation zone conclusions can also be applied to human-induced earthquakes.

Urea, a true uremic toxin: the empire strikes back.

Science.gov (United States)

Lau, Wei Ling; Vaziri, Nosratola D

2017-01-01

Blood levels of urea rise with progressive decline in kidney function. Older studies examining acute urea infusion suggested that urea was well-tolerated at levels 8-10× above normal values. More recent in vitro and in vivo work argue the opposite and demonstrate both direct and indirect toxicities of urea, which probably promote the premature aging phenotype that is pervasive in chronic kidney disease (CKD). Elevated urea at concentrations typically encountered in uremic patients induces disintegration of the gut epithelial barrier, leading to translocation of bacterial toxins into the bloodstream and systemic inflammation. Urea induces apoptosis of vascular smooth muscle cells as well as endothelial dysfunction, thus directly promoting cardiovascular disease. Further, urea stimulates oxidative stress and dysfunction in adipocytes, leading to insulin resistance. Finally, there are widespread indirect effects of elevated urea as a result of the carbamylation reaction, where isocyanic acid (a product of urea catabolism) alters the structure and function of proteins in the body. Carbamylation has been linked with renal fibrosis, atherosclerosis and anaemia. In summary, urea is a re-emerging Dark Force in CKD pathophysiology. Trials examining low protein diet to minimize accumulation of urea and other toxins suggest a clinical benefit in terms of slowing progression of CKD. © 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

Three-Fingered RAVERs: Rapid Accumulation of Variations in Exposed Residues of Snake Venom Toxins

Science.gov (United States)

Sunagar, Kartik; Jackson, Timothy N. W.; Undheim, Eivind A. B.; Ali, Syed. A.; Antunes, Agostinho; Fry, Bryan G.

2013-01-01

Three-finger toxins (3FTx) represent one of the most abundantly secreted and potently toxic components of colubrid (Colubridae), elapid (Elapidae) and psammophid (Psammophiinae subfamily of the Lamprophidae) snake venom arsenal. Despite their conserved structural similarity, they perform a diversity of biological functions. Although they are theorised to undergo adaptive evolution, the underlying diversification mechanisms remain elusive. Here, we report the molecular evolution of different 3FTx functional forms and show that positively selected point mutations have driven the rapid evolution and diversification of 3FTx. These diversification events not only correlate with the evolution of advanced venom delivery systems (VDS) in Caenophidia, but in particular the explosive diversification of the clade subsequent to the evolution of a high pressure, hollow-fanged VDS in elapids, highlighting the significant role of these toxins in the evolution of advanced snakes. We show that Type I, II and III α-neurotoxins have evolved with extreme rapidity under the influence of positive selection. We also show that novel Oxyuranus/Pseudonaja Type II forms lacking the apotypic loop-2 stabilising cysteine doublet characteristic of Type II forms are not phylogenetically basal in relation to other Type IIs as previously thought, but are the result of secondary loss of these apotypic cysteines on at least three separate occasions. Not all 3FTxs have evolved rapidly: κ-neurotoxins, which form non-covalently associated heterodimers, have experienced a relatively weaker influence of diversifying selection; while cytotoxic 3FTx, with their functional sites, dispersed over 40% of the molecular surface, have been extremely constrained by negative selection. We show that the a previous theory of 3FTx molecular evolution (termed ASSET) is evolutionarily implausible and cannot account for the considerable variation observed in very short segments of 3FTx. Instead, we propose a theory of

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

DEFF Research Database (Denmark)

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

2009-01-01

mucosal barrier as a key step in enteric pathogen survival. We review key observations relevant to the roles of LT and cholera toxin in protective immunity and the effects of these toxins on innate mucosal defenses. We suggest either that toxin-mediated fluid secretion mechanically disrupts the mucus...... layer or that toxins interfere with innate mucosal defenses by other means. Such a breach gives pathogens access to the enterocyte, leading to binding and pathogenicity by enterotoxigenic E. coli (ETEC) and other organisms. Given the common exposure to LT(+) ETEC by humans visiting or residing...... unexpectedly broad protective effects against LT(+) ETEC and mixed infections when using a toxin-based enteric vaccine. If toxins truly exert barrier-disruptive effects as a key step in pathogenesis, then a return to classic toxin-based vaccine strategies for enteric disease is warranted and can be expected...

Toxin-Induced Experimental Models of Learning and Memory Impairment.

Science.gov (United States)

More, Sandeep Vasant; Kumar, Hemant; Cho, Duk-Yeon; Yun, Yo-Sep; Choi, Dong-Kug

2016-09-01

Animal models for learning and memory have significantly contributed to novel strategies for drug development and hence are an imperative part in the assessment of therapeutics. Learning and memory involve different stages including acquisition, consolidation, and retrieval and each stage can be characterized using specific toxin. Recent studies have postulated the molecular basis of these processes and have also demonstrated many signaling molecules that are involved in several stages of memory. Most insights into learning and memory impairment and to develop a novel compound stems from the investigations performed in experimental models, especially those produced by neurotoxins models. Several toxins have been utilized based on their mechanism of action for learning and memory impairment such as scopolamine, streptozotocin, quinolinic acid, and domoic acid. Further, some toxins like 6-hydroxy dopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and amyloid-β are known to cause specific learning and memory impairment which imitate the disease pathology of Parkinson's disease dementia and Alzheimer's disease dementia. Apart from these toxins, several other toxins come under a miscellaneous category like an environmental pollutant, snake venoms, botulinum, and lipopolysaccharide. This review will focus on the various classes of neurotoxin models for learning and memory impairment with their specific mechanism of action that could assist the process of drug discovery and development for dementia and cognitive disorders.

Genetically modified anthrax lethal toxin safely delivers whole HIV protein antigens into the cytosol to induce T cell immunity

Science.gov (United States)

Lu, Yichen; Friedman, Rachel; Kushner, Nicholas; Doling, Amy; Thomas, Lawrence; Touzjian, Neal; Starnbach, Michael; Lieberman, Judy

2000-07-01

Bacillus anthrax lethal toxin can be engineered to deliver foreign proteins to the cytosol for antigen presentation to CD8 T cells. Vaccination with modified toxins carrying 8-9 amino acid peptide epitopes induces protective immunity in mice. To evaluate whether large protein antigens can be used with this system, recombinant constructs encoding several HIV antigens up to 500 amino acids were produced. These candidate HIV vaccines are safe in animals and induce CD8 T cells in mice. Constructs encoding gag p24 and nef stimulate gag-specific CD4 proliferation and a secondary cytotoxic T lymphocyte response in HIV-infected donor peripheral blood mononuclear cells in vitro. These results lay the foundation for future clinical vaccine studies.

Plant Insecticidal Toxins in Ecological Networks

Directory of Open Access Journals (Sweden)

Sébastien Ibanez

2012-04-01

Full Text Available 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.

Plant insecticidal toxins in ecological networks.

Science.gov (United States)

Ibanez, Sébastien; Gallet, Christiane; Després, Laurence

2012-04-01

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.

Botulinum Toxin and Muscle Atrophy: A Wanted or Unwanted Effect.

Science.gov (United States)

Durand, Paul D; Couto, Rafael A; Isakov, Raymond; Yoo, Donald B; Azizzadeh, Babak; Guyuron, Bahman; Zins, James E

2016-04-01

While the facial rejuvenating effect of botulinum toxin type A is well known and widespread, its use in body and facial contouring is less common. We first describe its use for deliberate muscle volume reduction, and then document instances of unanticipated and undesirable muscle atrophy. Finally, we investigate the potential long-term adverse effects of botulinum toxin-induced muscle atrophy. Although the use of botulinum toxin type A in the cosmetic patient has been extensively studied, there are several questions yet to be addressed. Does prolonged botulinum toxin treatment increase its duration of action? What is the mechanism of muscle atrophy and what is the cause of its reversibility once treatment has stopped? We proceed to examine how prolonged chemodenervation with botulinum toxin can increase its duration of effect and potentially contribute to muscle atrophy. Instances of inadvertent botulinum toxin-induced atrophy are also described. These include the "hourglass deformity" secondary to botulinum toxin type A treatment for migraine headaches, and a patient with atrophy of multiple facial muscles from injections for hemifacial spasm. Numerous reports demonstrate that muscle atrophy after botulinum toxin type A treatment occurs and is both reversible and temporary, with current literature supporting the notion that repeated chemodenervation with botulinum toxin likely responsible for both therapeutic and incidental temporary muscle atrophy. Furthermore, duration of response may be increased with subsequent treatments, thus minimizing frequency of reinjection. Practitioners should be aware of the temporary and reversible effect of botulinum toxin-induced muscle atrophy and be prepared to reassure patients on this matter. © 2016 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com.

Toxin- and cadmium-induced cell death events in tomato suspension cells resemble features of hypersensitive response

NARCIS (Netherlands)

Iakimova, E.T.; Woltering, E.J.; Yordanova, Z.P.

2007-01-01

Elicitors of different origin (fumonisin B1, fungal toxin), camptothecin (alkaloid from Camptotheca acuminata), mastoparan (wasp venom) and the heavy metal (cadmium) were tested for their ability to induce programmed cell death (PCD) in a model system of tomato cell culture, line MsK8. By employing

Botulinum toxin in the treatment of vocal fold nodules.

Science.gov (United States)

Allen, Jacqui E; Belafsky, Peter C

2009-12-01

Promising new techniques in the management of vocal fold nodules have been developed in the past 2 years. Simultaneously, the therapeutic use of botulinum toxin has rapidly expanded. This review explores the use of botulinum toxin in treatment of vocal nodules and summarizes current therapeutic concepts. New microsurgical instruments and techniques, refinements in laser technology, radiosurgical excision and steroid intralesional injections are all promising new techniques in the management of vocal nodules. Botulinum toxin-induced 'voice rest' is a new technique we have employed in patients with recalcitrant nodules. Successful resolution of nodules is possible with this technique, without the risk of vocal fold scarring inherent in dissection/excision techniques. Botulinum toxin usage is exponentially increasing, and large-scale, long-term studies demonstrate its safety profile. Targeted vocal fold temporary paralysis induced by botulinum toxin injection is a new, well tolerated and efficacious treatment in patients with persistent vocal fold nodules.

Nucleation speed limit on remote fluid-induced earthquakes

Science.gov (United States)

Parsons, Tom; Malagnini, Luca; Akinci, Aybige

2017-01-01

Earthquakes triggered by other remote seismic events are explained as a response to long-traveling seismic waves that temporarily stress the crust. However, delays of hours or days after seismic waves pass through are reported by several studies, which are difficult to reconcile with the transient stresses imparted by seismic waves. We show that these delays are proportional to magnitude and that nucleation times are best fit to a fluid diffusion process if the governing rupture process involves unlocking a magnitude-dependent critical nucleation zone. It is well established that distant earthquakes can strongly affect the pressure and distribution of crustal pore fluids. Earth’s crust contains hydraulically isolated, pressurized compartments in which fluids are contained within low-permeability walls. We know that strong shaking induced by seismic waves from large earthquakes can change the permeability of rocks. Thus, the boundary of a pressurized compartment may see its permeability rise. Previously confined, overpressurized pore fluids may then diffuse away, infiltrate faults, decrease their strength, and induce earthquakes. Magnitude-dependent delays and critical nucleation zone conclusions can also be applied to human-induced earthquakes. PMID:28845448

Propionate induces cell swelling and K+ accumulation in shark rectal gland

International Nuclear Information System (INIS)

Feldman, G.M.; Ziyadeh, F.N.; Mills, J.W.; Booz, G.W.; Kleinzeller, A.

1989-01-01

Small organic anions have been reported to induce cell solute accumulation and swelling. To investigate the mechanism of swelling, we utilized preparations of rectal gland cells from Squalus acanthias incubated in medium containing propionate. Propionate causes cells to swell by diffusing across membranes in its nonionic form, acidifying cell contents, and activating the Na+-H+ antiporter. The Na+-H+ exchange process tends to correct intracellular pH (pHi), and thus it maintains a favorable gradient for propionic acid diffusion and allows propionate to accumulate. Activation of the Na+-H+ antiport also facilitates Na+ entry into the cell and Nai accumulation. At the same time Na+-K+-ATPase activity, unaffected by propionate, replaces Nai with Ki, whereas the K+ leak rate, decreased by propionate, allows Ki to accumulate. As judged by 86 Rb+ efflux, the reduction in K+ leak was not due to propionate-induced cell acidification or reduction in Cli concentration. Despite inducing cell swelling, propionate did not disrupt cell structural elements and F actin distribution along cell membranes

Propionate induces cell swelling and K+ accumulation in shark rectal gland

Energy Technology Data Exchange (ETDEWEB)

Feldman, G.M.; Ziyadeh, F.N.; Mills, J.W.; Booz, G.W.; Kleinzeller, A. (Mount Desert Island Biological Laboratory, Salsbury Cove, ME (USA))

1989-08-01

Small organic anions have been reported to induce cell solute accumulation and swelling. To investigate the mechanism of swelling, we utilized preparations of rectal gland cells from Squalus acanthias incubated in medium containing propionate. Propionate causes cells to swell by diffusing across membranes in its nonionic form, acidifying cell contents, and activating the Na+-H+ antiporter. The Na+-H+ exchange process tends to correct intracellular pH (pHi), and thus it maintains a favorable gradient for propionic acid diffusion and allows propionate to accumulate. Activation of the Na+-H+ antiport also facilitates Na+ entry into the cell and Nai accumulation. At the same time Na+-K+-ATPase activity, unaffected by propionate, replaces Nai with Ki, whereas the K+ leak rate, decreased by propionate, allows Ki to accumulate. As judged by {sup 86}Rb+ efflux, the reduction in K+ leak was not due to propionate-induced cell acidification or reduction in Cli concentration. Despite inducing cell swelling, propionate did not disrupt cell structural elements and F actin distribution along cell membranes.

ABMA, a small molecule that inhibits intracellular toxins and pathogens by interfering with late endosomal compartments.

Science.gov (United States)

Wu, Yu; Pons, Valérie; Goudet, Amélie; Panigai, Laetitia; Fischer, Annette; Herweg, Jo-Ana; Kali, Sabrina; Davey, Robert A; Laporte, Jérôme; Bouclier, Céline; Yousfi, Rahima; Aubenque, Céline; Merer, Goulven; Gobbo, Emilie; Lopez, Roman; Gillet, Cynthia; Cojean, Sandrine; Popoff, Michel R; Clayette, Pascal; Le Grand, Roger; Boulogne, Claire; Tordo, Noël; Lemichez, Emmanuel; Loiseau, Philippe M; Rudel, Thomas; Sauvaire, Didier; Cintrat, Jean-Christophe; Gillet, Daniel; Barbier, Julien

2017-11-14

Intracellular pathogenic microorganisms and toxins exploit host cell mechanisms to enter, exert their deleterious effects as well as hijack host nutrition for their development. A potential approach to treat multiple pathogen infections and that should not induce drug resistance is the use of small molecules that target host components. We identified the compound 1-adamantyl (5-bromo-2-methoxybenzyl) amine (ABMA) from a cell-based high throughput screening for its capacity to protect human cells and mice against ricin toxin without toxicity. This compound efficiently protects cells against various toxins and pathogens including viruses, intracellular bacteria and parasite. ABMA provokes Rab7-positive late endosomal compartment accumulation in mammalian cells without affecting other organelles (early endosomes, lysosomes, the Golgi apparatus, the endoplasmic reticulum or the nucleus). As the mechanism of action of ABMA is restricted to host-endosomal compartments, it reduces cell infection by pathogens that depend on this pathway to invade cells. ABMA may represent a novel class of broad-spectrum compounds with therapeutic potential against diverse severe infectious diseases.

Ondansetron can enhance cisplatin-induced nephrotoxicity via inhibition of multiple toxin and extrusion proteins (MATEs)

International Nuclear Information System (INIS)

Li, Qing; Guo, Dong; Dong, Zhongqi; Zhang, Wei; Zhang, Lei; Huang, Shiew-Mei; Polli, James E.; Shu, Yan

2013-01-01

The nephrotoxicity limits the clinical application of cisplatin. Human organic cation transporter 2 (OCT2) and multidrug and toxin extrusion proteins (MATEs) work in concert in the elimination of cationic drugs such as cisplatin from the kidney. We hypothesized that co-administration of ondansetron would have an effect on cisplatin nephrotoxicity by altering the function of cisplatin transporters. The inhibitory potencies of ondansetron on metformin accumulation mediated by OCT2 and MATEs were determined in the stable HEK-293 cells expressing these transporters. The effects of ondansetron on drug disposition in vivo were examined by conducting the pharmacokinetics of metformin, a classical substrate for OCTs and MATEs, in wild-type and Mate1−/− mice. The nephrotoxicity was assessed in the wild-type and Mate1−/− mice received cisplatin with and without ondansetron. Both MATEs, including human MATE1, human MATE2-K, and mouse Mate1, and OCT2 (human and mouse) were subject to ondansetron inhibition, with much greater potencies by ondansetron on MATEs. Ondansetron significantly increased tissue accumulation and pharmacokinetic exposure of metformin in wild-type but not in Mate1−/− mice. Moreover, ondansetron treatment significantly enhanced renal accumulation of cisplatin and cisplatin-induced nephrotoxicity which were indicated by increased levels of biochemical and molecular biomarkers and more severe pathohistological changes in mice. Similar increases in nephrotoxicity were caused by genetic deficiency of MATE function in mice. Therefore, the potent inhibition of MATEs by ondansetron enhances the nephrotoxicity associated with cisplatin treatment in mice. Potential nephrotoxic effects of combining the chemotherapeutic cisplatin and the antiemetic 5-hydroxytryptamine-3 (5-HT 3 ) receptor antagonists, such as ondansetron, should be investigated in patients. - Highlights: • Nephrotoxicity significantly limits clinical use of the chemotherapeutic cisplatin

Ondansetron can enhance cisplatin-induced nephrotoxicity via inhibition of multiple toxin and extrusion proteins (MATEs)

Energy Technology Data Exchange (ETDEWEB)

Li, Qing [Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, MD (United States); Institute of Clinical Pharmacology, Central South University, Hunan 410078 (China); Guo, Dong [Institute of Clinical Pharmacology, Central South University, Hunan 410078 (China); Dong, Zhongqi [Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, MD (United States); Zhang, Wei [Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, MD (United States); Institute of Clinical Pharmacology, Central South University, Hunan 410078 (China); Zhang, Lei; Huang, Shiew-Mei [Office of Clinical Pharmacology, Office of Translational Sciences, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD (United States); Polli, James E. [Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, MD (United States); Shu, Yan, E-mail: yshu@rx.umaryland.edu [Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, MD (United States)

2013-11-15

The nephrotoxicity limits the clinical application of cisplatin. Human organic cation transporter 2 (OCT2) and multidrug and toxin extrusion proteins (MATEs) work in concert in the elimination of cationic drugs such as cisplatin from the kidney. We hypothesized that co-administration of ondansetron would have an effect on cisplatin nephrotoxicity by altering the function of cisplatin transporters. The inhibitory potencies of ondansetron on metformin accumulation mediated by OCT2 and MATEs were determined in the stable HEK-293 cells expressing these transporters. The effects of ondansetron on drug disposition in vivo were examined by conducting the pharmacokinetics of metformin, a classical substrate for OCTs and MATEs, in wild-type and Mate1−/− mice. The nephrotoxicity was assessed in the wild-type and Mate1−/− mice received cisplatin with and without ondansetron. Both MATEs, including human MATE1, human MATE2-K, and mouse Mate1, and OCT2 (human and mouse) were subject to ondansetron inhibition, with much greater potencies by ondansetron on MATEs. Ondansetron significantly increased tissue accumulation and pharmacokinetic exposure of metformin in wild-type but not in Mate1−/− mice. Moreover, ondansetron treatment significantly enhanced renal accumulation of cisplatin and cisplatin-induced nephrotoxicity which were indicated by increased levels of biochemical and molecular biomarkers and more severe pathohistological changes in mice. Similar increases in nephrotoxicity were caused by genetic deficiency of MATE function in mice. Therefore, the potent inhibition of MATEs by ondansetron enhances the nephrotoxicity associated with cisplatin treatment in mice. Potential nephrotoxic effects of combining the chemotherapeutic cisplatin and the antiemetic 5-hydroxytryptamine-3 (5-HT{sub 3}) receptor antagonists, such as ondansetron, should be investigated in patients. - Highlights: • Nephrotoxicity significantly limits clinical use of the chemotherapeutic

Flavonoids-induced accumulation of hypoxia-inducible factor (HIF)-1alpha/2alpha is mediated through chelation of iron.

Science.gov (United States)

Park, Sung-Soo; Bae, Insoo; Lee, Yong J

2008-04-15

Hypoxia-inducible factor-1 alpha (HIF-1alpha) is the regulatory subunit of the heterodimeric transcription factor HIF-1 that is the key regulator of cellular response to low oxygen tension. Under normoxic conditions, HIF-1alpha is continuously degraded by the ubiquitin-proteasome pathway through pVHL (von Hippel-Lindau tumor suppressor protein). Under hypoxic conditions, HIF-1alpha is stabilized and induces the transcription of HIF-1 target genes. Quercetin, a flavonoid with anti-oxidant, anti-inflammatory, and kinase modulating properties, has been found to induce HIF-1alpha accumulation and VEGF secretion in normoxia. In this study, the molecular mechanisms of quercetin-mediated HIF-1alpha accumulation were investigated. Previous studies have shown that, in addition to being induced by hypoxia, HIF-1alpha can be induced through the phosphatidylinositol 3-kinase (PI3K)/Akt and p53 signaling pathways. But our study revealed, through p53 mutant-type as well as p53 null cell lines, that neither the PI3K/Akt nor the p53 signaling pathway is required for quercetin-induced HIF-1alpha accumulation. And we observed that HIF-1alpha accumulated by quercetin is not ubiquitinated and the interaction of HIF-1alpha with pVHL is reduced, compared with HIF-1alpha accumulated by the proteasome inhibitor MG132. The use of quercetin's analogues showed that only quercetin and galangin induce HIF-1/2alpha accumulation and this effect is completely reversed by additional iron ions. This is because quercetin and galangin are able to chelate cellular iron ions that are cofactors of HIF-1/2alpha proline hydroxylase (PHD). These data suggest that quercetin inhibits the ubiquitination of HIF-1/2alpha in normoxia by hindering PHD through chelating iron ions.

Pertussis toxin, an inhibitor of G(αi PCR, inhibits bile acid- and cytokine-induced apoptosis in primary rat hepatocytes.

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Golnar Karimian

Full Text Available Excessive hepatocyte apoptosis is a common event in acute and chronic liver diseases leading to loss of functional liver tissue. Approaches to prevent apoptosis have therefore high potential for the treatment of liver disease. G-protein coupled receptors (GPCR play crucial roles in cell fate (proliferation, cell death and act through heterotrimeric G-proteins. G(αiPCRs have been shown to regulate lipoapoptosis in hepatocytes, but their role in inflammation- or bile acid-induced apoptosis is unknown. Here, we analyzed the effect of inhibiting G(αiPCR function, using pertussis toxin (PT, on bile acid- and cytokine-induced apoptosis in hepatocytes. Primary rat hepatocytes, HepG2-rNtcp cells (human hepatocellular carcinoma cells or H-4-II-E cells (rat hepatoma cells were exposed to glycochenodeoxycholic acid (GCDCA or tumor necrosis factor-α (TNFα/actinomycin D (ActD. PT (50-200 nmol/L was added 30 minutes prior to the apoptotic stimulus. Apoptosis (caspase-3 activity, acridine orange staining and necrosis (sytox green staining were assessed. PT significantly reduced GCDCA- and TNFα/ActD-induced apoptosis in rat hepatocytes (-60%, p<0.05 in a dose-dependent manner (with no shift to necrosis, but not in HepG2-rNtcp cells or rat H-4-II-E cells. The protective effect of pertussis toxin was independent of the activation of selected cell survival signal transduction pathways, including ERK, p38 MAPK, PI3K and PKC pathways, as specific protein kinase inhibitors did not reverse the protective effects of pertussis toxin in GCDCA-exposed hepatocytes.Pertussis toxin, an inhibitor of G(αiPCRs, protects hepatocytes, but not hepatocellular carcinoma cells, against bile acid- and cytokine-induced apoptosis and has therapeutic potential as primary hepatoprotective drug, as well as adjuvant in anti-cancer therapy.

Toxins and derivatives in molecular pharmaceutics: Drug delivery and targeted therapy.

Science.gov (United States)

Zhan, Changyou; Li, Chong; Wei, Xiaoli; Lu, Wuyuan; Lu, Weiyue

2015-08-01

Protein and peptide toxins offer an invaluable source for the development of actively targeted drug delivery systems. They avidly bind to a variety of cognate receptors, some of which are expressed or even up-regulated in diseased tissues and biological barriers. Protein and peptide toxins or their derivatives can act as ligands to facilitate tissue- or organ-specific accumulation of therapeutics. Some toxins have evolved from a relatively small number of structural frameworks that are particularly suitable for addressing the crucial issues of potency and stability, making them an instrumental source of leads and templates for targeted therapy. The focus of this review is on protein and peptide toxins for the development of targeted drug delivery systems and molecular therapies. We summarize disease- and biological barrier-related toxin receptors, as well as targeted drug delivery strategies inspired by those receptors. The design of new therapeutics based on protein and peptide toxins is also discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Dinophysis Toxins: Causative Organisms, Distribution and Fate in Shellfish

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Beatriz Reguera

2014-01-01

Full Text Available Several Dinophysis species produce diarrhoetic toxins (okadaic acid and dinophysistoxins and pectenotoxins, and cause gastointestinal illness, Diarrhetic Shellfish Poisoning (DSP, even at low cell densities (<103 cells·L−1. They are the main threat, in terms of days of harvesting bans, to aquaculture in Northern Japan, Chile, and Europe. Toxicity and toxin profiles are very variable, more between strains than species. The distribution of DSP events mirrors that of shellfish production areas that have implemented toxin regulations, otherwise misinterpreted as bacterial or viral contamination. Field observations and laboratory experiments have shown that most of the toxins produced by Dinophysis are released into the medium, raising questions about the ecological role of extracelular toxins and their potential uptake by shellfish. Shellfish contamination results from a complex balance between food selection, adsorption, species-specific enzymatic transformations, and allometric processes. Highest risk areas are those combining Dinophysis strains with high cell content of okadaates, aquaculture with predominance of mytilids (good accumulators of toxins, and consumers who frequently include mussels in their diet. Regions including pectenotoxins in their regulated phycotoxins will suffer from much longer harvesting bans and from disloyal competition with production areas where these toxins have been deregulated.

Discovery of novel bacterial toxins by genomics and computational biology.

Science.gov (United States)

Doxey, Andrew C; Mansfield, Michael J; Montecucco, Cesare

2018-06-01

Hundreds and hundreds of bacterial protein toxins are presently known. Traditionally, toxin identification begins with pathological studies of bacterial infectious disease. Following identification and cultivation of a bacterial pathogen, the protein toxin is purified from the culture medium and its pathogenic activity is studied using the methods of biochemistry and structural biology, cell biology, tissue and organ biology, and appropriate animal models, supplemented by bioimaging techniques. The ongoing and explosive development of high-throughput DNA sequencing and bioinformatic approaches have set in motion a revolution in many fields of biology, including microbiology. One consequence is that genes encoding novel bacterial toxins can be identified by bioinformatic and computational methods based on previous knowledge accumulated from studies of the biology and pathology of thousands of known bacterial protein toxins. Starting from the paradigmatic cases of diphtheria toxin, tetanus and botulinum neurotoxins, this review discusses traditional experimental approaches as well as bioinformatics and genomics-driven approaches that facilitate the discovery of novel bacterial toxins. We discuss recent work on the identification of novel botulinum-like toxins from genera such as Weissella, Chryseobacterium, and Enteroccocus, and the implications of these computationally identified toxins in the field. Finally, we discuss the promise of metagenomics in the discovery of novel toxins and their ecological niches, and present data suggesting the existence of uncharacterized, botulinum-like toxin genes in insect gut metagenomes. Copyright © 2018. Published by Elsevier Ltd.

Clostridium botulinum C2 toxin--new insights into the cellular up-take of the actin-ADP-ribosylating toxin.

Science.gov (United States)

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.

Earthworm-Derived Pore-Forming Toxin Lysenin and Screening of Its Inhibitors

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Neelanun Sukumwang

2013-08-01

Full Text Available Lysenin is a pore-forming toxin from the coelomic fluid of earthworm Eisenia foetida. This protein specifically binds to sphingomyelin and induces erythrocyte lysis. Lysenin consists of 297 amino acids with a molecular weight of 41 kDa. We screened for cellular signal transduction inhibitors of low molecular weight from microorganisms and plants. The purpose of the screening was to study the mechanism of diseases using the obtained inhibitors and to develop new chemotherapeutic agents acting in the new mechanism. Therefore, our aim was to screen for inhibitors of Lysenin-induced hemolysis from plant extracts and microbial culture filtrates. As a result, we isolated all-E-lutein from an extract of Dalbergia latifolia leaves. All-E-lutein is likely to inhibit the process of Lysenin-membrane binding and/or oligomer formation rather than pore formation. Additionally, we isolated tyrosylproline anhydride from the culture filtrate of Streptomyces as an inhibitor of Lysenin-induced hemolysis.

Oxidative Stress in Shiga Toxin Production by Enterohemorrhagic Escherichia coli

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Katarzyna Licznerska

2016-01-01

Full Text Available Virulence of enterohemorrhagic Escherichia coli (EHEC strains depends on production of Shiga toxins. These toxins are encoded in genomes of lambdoid bacteriophages (Shiga toxin-converting phages, present in EHEC cells as prophages. The genes coding for Shiga toxins are silent in lysogenic bacteria, and prophage induction is necessary for their efficient expression and toxin production. Under laboratory conditions, treatment with UV light or antibiotics interfering with DNA replication are commonly used to induce lambdoid prophages. Since such conditions are unlikely to occur in human intestine, various research groups searched for other factors or agents that might induce Shiga toxin-converting prophages. Among other conditions, it was reported that treatment with H2O2 caused induction of these prophages, though with efficiency significantly lower relative to UV-irradiation or mitomycin C treatment. A molecular mechanism of this phenomenon has been proposed. It appears that the oxidative stress represents natural conditions provoking induction of Shiga toxin-converting prophages as a consequence of H2O2 excretion by either neutrophils in infected humans or protist predators outside human body. Finally, the recently proposed biological role of Shiga toxin production is described in this paper, and the “bacterial altruism” and “Trojan Horse” hypotheses, which are connected to the oxidative stress, are discussed.

Elimination of Endogenous Toxin, Creatinine from Blood Plasma Depends on Albumin Conformation: Site Specific Uremic Toxicity & Impaired Drug Binding

Science.gov (United States)

Varshney, Ankita; Rehan, Mohd; Subbarao, Naidu; Rabbani, Gulam; Khan, Rizwan Hasan

2011-01-01

Uremic syndrome results from malfunctioning of various organ systems due to the retention of uremic toxins which, under normal conditions, would be excreted into the urine and/or metabolized by the kidneys. The aim of this study was to elucidate the mechanisms underlying the renal elimination of uremic toxin creatinine that accumulate in chronic renal failure. Quantitative investigation of the plausible correlations was performed by spectroscopy, calorimetry, molecular docking and accessibility of surface area. Alkalinization of normal plasma from pH 7.0 to 9.0 modifies the distribution of toxin in the body and therefore may affect both the accumulation and the rate of toxin elimination. The ligand loading of HSA with uremic toxin predicts several key side chain interactions of site I that presumably have the potential to impact the specificity and impaired drug binding. These findings provide useful information for elucidating the complicated mechanism of toxin disposition in renal disease state. PMID:21386972

The opposing effects of calmodulin, adenosine 5 prime -triphosphate, and pertussis toxin on phorbol ester induced inhibition of atrial natriuretic factor stimulated guanylate cyclase in SK-NEP-1 cells

Energy Technology Data Exchange (ETDEWEB)

Sekiya, M.; Frohlich, E.D.; Cole, F.E. (Alton Ochsner Medical Foundation, New Orleans, LA (USA))

1991-01-01

In the present study, we investigated the effects of calmodulin, adenosine 5{prime}-triphosphate (ATP) and pertussis toxin (PT) on phorbol ester (PMA) induced inhibition of ANF-stimulated cyclic GMP formation in cells from the human renal cell line, SK-NEP-1. PMA inhibited ANF-stimulated guanylate cyclase activity in particulate membranes by about 65%. Calmodulin reversed this inhibition in a dose dependent manner. ATP potentiated Mg++ but not Mn++ supported guanylate cyclase activity. In PMA treated membranes, ATP potentiating effects were abolished. PMA also inhibited ANF-stimulated cGMP accumulation, but pretreatment with PT prevented this PMA inhibition. PT did not affect basal or ANF-stimulated cGMP accumulation. In conclusion, these results demonstrated that PMA inhibited ANF stimulation of particulate guanylate cyclase in opposition to the activating effects of calmodulin or ATP in SK-NEP-1 cells. The protein kinase C inhibitory effects appeared to be mediated via a PT-sensitive G protein.

Bacterial toxins as pathogen weapons against phagocytes

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Ana edo Vale

2016-02-01

Full Text Available Bacterial toxins are virulence factors that manipulate host cell functions and take over the control of vital processes of living organisms to favour microbial infection. Some toxins directly target innate immune cells, thereby annihilating a major branch of the host immune response. In this review we will focus on bacterial toxins that act from the extracellular milieu and hinder the function of macrophages and neutrophils. In particular, we will concentrate on toxins from Gram-positive and Gram-negative bacteria that manipulate cell signalling or induce cell death by either imposing direct damage to the host cells cytoplasmic membrane or enzymatically modifying key eukaryotic targets. Outcomes regarding pathogen dissemination, host damage and disease progression will be discussed.

Rotavirus 2/6 Viruslike Particles Administered Intranasally with Cholera Toxin, Escherichia coli Heat-Labile Toxin (LT), and LT-R192G Induce Protection from Rotavirus Challenge

Science.gov (United States)

O’Neal, Christine M.; Clements, John D.; Estes, Mary K.; Conner, Margaret E.

1998-01-01

We have shown that rotavirus 2/6 viruslike particles composed of proteins VP2 and VP6 (2/6-VLPs) administered to mice intranasally with cholera toxin (CT) induced protection from rotavirus challenge, as measured by virus shedding. Since it is unclear if CT will be approved for human use, we evaluated the adjuvanticity of Escherichia coli heat-labile toxin (LT) and LT-R192G. Mice were inoculated intranasally with 10 μg of 2/6-VLPs combined with CT, LT, or LT-R192G. All three adjuvants induced equivalent geometric mean titers of rotavirus-specific serum antibody and intestinal immunoglobulin G (IgG). Mice inoculated with 2/6-VLPs with LT produced significantly higher titers of intestinal IgA than mice given CT as the adjuvant. All mice inoculated with 2/6-VLPs mixed with LT and LT-R192G were totally protected (100%) from rotavirus challenge, while mice inoculated with 2/6-VLPs mixed with CT showed a mean 91% protection from challenge. The availability of a safe, effective mucosal adjuvant such as LT-R192G will increase the practicality of administering recombinant vaccines mucosally. PMID:9525668

Fidaxomicin Inhibits Clostridium difficile Toxin A-Mediated Enteritis in the Mouse Ileum

Science.gov (United States)

Koon, Hon Wai; Ho, Samantha; Hing, Tressia C.; Cheng, Michelle; Chen, Xinhua; Ichikawa, Yoshi; Kelly, Ciarán P.

2014-01-01

Clostridium difficile infection (CDI) is a common, debilitating infection with high morbidity and mortality. C. difficile causes diarrhea and intestinal inflammation by releasing two toxins, toxin A and toxin B. The macrolide antibiotic fidaxomicin was recently shown to be effective in treating CDI, and its beneficial effect was associated with fewer recurrent infections in CDI patients. Since other macrolides possess anti-inflammatory properties, we examined the possibility that fidaxomicin alters C. difficile toxin A-induced ileal inflammation in mice. The ileal loops of anesthetized mice were injected with fidaxomicin (5, 10, or 20 μM), and after 30 min, the loops were injected with purified C. difficile toxin A or phosphate-buffered saline alone. Four hours after toxin A administration, ileal tissues were processed for histological evaluation (epithelial cell damage, neutrophil infiltration, congestion, and edema) and cytokine measurements. C. difficile toxin A caused histologic damage, evidenced by increased mean histologic score and ileal interleukin-1β (IL-1β) protein and mRNA expression. Treatment with fidaxomicin (20 μM) or its primary metabolite, OP-1118 (120 μM), significantly inhibited toxin A-mediated histologic damage and reduced the mean histology score and ileal IL-1β protein and mRNA expression. Both fidaxomicin and OP-1118 reduced toxin A-induced cell rounding in human colonic CCD-18Co fibroblasts. Treatment of ileal loops with vancomycin (20 μM) and metronidazole (20 μM) did not alter toxin A-induced histologic damage and IL-1β protein expression. In addition to its well known antibacterial effects against C. difficile, fidaxomicin may possess anti-inflammatory activity directed against the intestinal effects of C. difficile toxins. PMID:24890583

Paralytic Toxins Accumulation and Tissue Expression of α-Amylase and Lipase Genes in the Pacific Oyster Crassostrea gigas Fed with the Neurotoxic Dinoflagellate Alexandrium catenella

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Mohamed Laabir

2012-11-01

Full Text Available The pacific oyster Crassostrea gigas was experimentally exposed to the neurotoxic Alexandrium catenella and a non-producer of PSTs, Alexandrium tamarense (control algae, at concentrations corresponding to those observed during the blooming period. At fixed time intervals, from 0 to 48 h, we determined the clearance rate, the total filtered cells, the composition of the fecal ribbons, the profile of the PSP toxins and the variation of the expression of two α-amylase and triacylglecerol lipase precursor (TLP genes through semi-quantitative RT-PCR. The results showed a significant decrease of the clearance rate of C. gigas fed with both Alexandrium species. However, from 29 to 48 h, the clearance rate and cell filtration activity increased only in oysters fed with A. tamarense. The toxin concentrations in the digestive gland rose above the sanitary threshold in less than 48 h of exposure and GTX6, a compound absent in A. catenella cells, accumulated. The α-amylase B gene expression level increased significantly in the time interval from 6 to 48 h in the digestive gland of oysters fed with A. tamarense, whereas the TLP gene transcript was significantly up-regulated in the digestive gland of oysters fed with the neurotoxic A. catenella. All together, these results suggest that the digestion capacity could be affected by PSP toxins.

Delayed Toxicity Associated with Soluble Anthrax Toxin Receptor Decoy-Ig Fusion Protein Treatment

Science.gov (United States)

Cote, Christopher; Welkos, Susan; Manchester, Marianne; Young, John A. T.

2012-01-01

Soluble receptor decoy inhibitors, including receptor-immunogloubulin (Ig) fusion proteins, have shown promise as candidate anthrax toxin therapeutics. These agents act by binding to the receptor-interaction site on the protective antigen (PA) toxin subunit, thereby blocking toxin binding to cell surface receptors. Here we have made the surprising observation that co-administration of receptor decoy-Ig fusion proteins significantly delayed, but did not protect, rats challenged with anthrax lethal toxin. The delayed toxicity was associated with the in vivo assembly of a long-lived complex comprised of anthrax lethal toxin and the receptor decoy-Ig inhibitor. Intoxication in this system presumably results from the slow dissociation of the toxin complex from the inhibitor following their prolonged circulation. We conclude that while receptor decoy-Ig proteins represent promising candidates for the early treatment of B. anthracis infection, they may not be suitable for therapeutic use at later stages when fatal levels of toxin have already accumulated in the bloodstream. PMID:22511955

Actions of cholera toxin and the prevention and treatment of cholera

Science.gov (United States)

Holmgren, Jan

1981-07-01

The drastic intestinal secretion of fluid and electrolytes that is characteristic of cholera is the result of reasonably well understood cellular and biochemical actions of the toxin secreted by Vibrio cholerae. Based on this understanding it is possible to devise new techniques for the treatment and prophylaxis of cholera to complement those based on fluid replacement therapy and sanitation.

An extensive microarray analysis of AAL-toxin-induced cell death in Arabidopsis thaliana brings new insights into the complexity of programmed cell death in plants

NARCIS (Netherlands)

Gechev, T.S.; Gadjev, I.Z.; Hille, J.

2004-01-01

A T-DNA knockout of the Arabidopsis homologue of the tomato disease resistance gene Asc was obtained. The asc gene renders plants sensitive to programmed cell death (PCD) triggered by the fungal AAL toxin. To obtain more insights into the nature of AAL-toxin-induced cell death and to identify genes

The impact of routine open nonsuction drainage on fluid accumulation after thyroid surgery: a prospective randomised clinical trial.

LENUS (Irish Health Repository)

Neary, Peter M

2012-01-01

Thyroid drains following thyroid surgery are routinely used despite minimal supportive evidence. Our aim in this study is to determine the impact of routine open drainage of the thyroid bed postoperatively on ultrasound-determined fluid accumulation at 24 hours.

Zinc oxide nanoparticles provide anti-cholera activity by disrupting the interaction of cholera toxin with the human GM1 receptor.

Science.gov (United States)

Sarwar, Shamila; Ali, Asif; Pal, Mahadeb; Chakrabarti, Pinak

2017-11-03

Vibrio cholerae causes cholera and is the leading cause of diarrhea in developing countries, highlighting the need for the development of new treatment strategies to combat this disease agent. While exploring the possibility of using zinc oxide (ZnO) nanoparticles (NPs) in cholera treatment, we previously found that ZnO NPs reduce fluid accumulation in mouse ileum induced by the cholera toxin (CT) protein. To uncover the mechanism of action of ZnO NPs on CT activity, here we used classical (O395) and El Tor (C6706) V. cholerae biotypes in growth and biochemical assays. We found that a ZnO NP concentration of 10 μg/ml did not affect the growth rates of these two strains, nor did we observe that ZnO NPs reduce the expression levels of CT mRNA and protein. It was observed that ZnO NPs form a complex with CT, appear to disrupt the CT secondary structure, and block its interaction with the GM1 ganglioside receptor in the outer leaflet of the plasma membrane in intestinal (HT-29) cells and thereby reduce CT uptake into the cells. In the range of 2.5-10 μg/ml, ZnO NPs exhibited no cytotoxicity on kidney (HEK293) and HT-29 cells. We conclude that ZnO NPs prevent the first step in the translocation of cholera toxin into intestinal epithelial cells without exerting measurable toxic effects on HEK293 and HT-29 cells. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Botulinum toxin-induced acute anterior uveitis in a patient with Behçet's disease under infliximab treatment: a case report.

Science.gov (United States)

Sasajima, Hirofumi; Yagi, Syunsuke; Osada, Hiromu; Zako, Masahiro

2017-05-04

Injections of lipopolysaccharide in animal models generate acute anterior uveitis (also known as endotoxin-induced uveitis), but the effects of lipopolysaccharide injection are unknown in humans. We describe an unusual case in which acute anterior uveitis was dramatically activated subsequent to botulinum toxin injection in a patient with Behçet's disease but the acute anterior uveitis was satisfactorily attenuated by infliximab. A 53-year-old Japanese man had normal ocular findings at his regularly scheduled appointment. He had been diagnosed as having incomplete-type Behçet's disease 11 years before. Three years after the diagnosis he was given systemic infusions of 5 mg/kg infliximab every 8 weeks and he had not experienced a uveitis attack for 8 years with no treatment other than infliximab. Two days after the eye examination, he received intracutaneous botulinum toxin injections to treat axillary hyperhidrosis on both sides. Three hours after the injections, he noted rapidly increasing floaters in his right eye. Four days after the injections, his right eye showed severe acute anterior uveitis with deteriorated aqueous flare and anterior vitreous opacity. He received his scheduled infliximab injection, and the right acute anterior uveitis immediately attenuated. Botulinum toxin may have clinical effects similar to those of lipopolysaccharide in endotoxin-induced uveitis models. To the best of our knowledge, this is the first report to suggest that botulinum toxin may trigger acute anterior uveitis, although the precise mechanism is still unclear.

Lipoproteins/peptides are sepsis-inducing toxins from bacteria that can be neutralized by synthetic anti-endotoxin peptides.

Science.gov (United States)

Martinez de Tejada, Guillermo; Heinbockel, Lena; Ferrer-Espada, Raquel; Heine, Holger; Alexander, Christian; Bárcena-Varela, Sergio; Goldmann, Torsten; Correa, Wilmar; Wiesmüller, Karl-Heinz; Gisch, Nicolas; Sánchez-Gómez, Susana; Fukuoka, Satoshi; Schürholz, Tobias; Gutsmann, Thomas; Brandenburg, Klaus

2015-09-22

Sepsis, a life-threatening syndrome with increasing incidence worldwide, is triggered by an overwhelming inflammation induced by microbial toxins released into the bloodstream during infection. A well-known sepsis-inducing factor is the membrane constituent of Gram-negative bacteria, lipopolysaccharide (LPS), signalling via Toll-like receptor-4. Although sepsis is caused in more than 50% cases by Gram-positive and mycoplasma cells, the causative compounds are still poorly described. In contradicting investigations lipoproteins/-peptides (LP), lipoteichoic acids (LTA), and peptidoglycans (PGN), were made responsible for eliciting this pathology. Here, we used human mononuclear cells from healthy donors to determine the cytokine-inducing activity of various LPs from different bacterial origin, synthetic and natural, and compared their activity with that of natural LTA and PGN. We demonstrate that LP are the most potent non-LPS pro-inflammatory toxins of the bacterial cell walls, signalling via Toll-like receptor-2, not only in vitro, but also when inoculated into mice: A synthetic LP caused sepsis-related pathological symptoms in a dose-response manner. Additionally, these mice produced pro-inflammatory cytokines characteristic of a septic reaction. Importantly, the recently designed polypeptide Aspidasept(®) which has been proven to efficiently neutralize LPS in vivo, inhibited cytokines induced by the various non-LPS compounds protecting animals from the pro-inflammatory activity of synthetic LP.

Dynamics of plc gene transcription and α-toxin production during growth of Clostridium perfringens strains with contrasting α-toxin production

DEFF Research Database (Denmark)

Abildgaard, Lone; Schramm, Andreas; Rudi, Knut

2009-01-01

The aim of the present study was to investigate transcription dynamics of the α-toxin-encoding plc gene relative to two housekeeping genes (gyrA and rplL) in batch cultures of three Clostridium perfringens strains with low, intermediate, and high levels of α-toxin production, respectively. The plc...... transcript level was always low in the low α-toxin producing strain. For the two other strains, plc transcription showed an inducible pattern and reached a maximum level in the late exponential growth phase. The transcription levels were however inversely correlated to α-toxin production for the two strains....... We propose that this discrepancy is due to differences in plc translation rates between the strains and that strain-specific translational rates therefore must be determined before α-toxin production can be extrapolated from transcript levels in C. perfringens....

A chloroplast lipoxygenase is required for wound-induced jasmonic acid accumulation in Arabidopsis.

Science.gov (United States)

Bell, E; Creelman, R A; Mullet, J E

1995-09-12

Plant lipoxygenases are thought to be involved in the biosynthesis of lipid-derived signaling molecules. The potential involvement of a specific Arabidopsis thaliana lipoxygenase isozyme, LOX2, in the biosynthesis of the plant growth regulators jasmonic acid (JA) and abscisic acid was investigated. Our characterization of LOX2 indicates that the protein is targeted to chloroplasts. The physiological role of this chloroplast lipoxygenase was analyzed in transgenic plants where cosuppression reduced LOX2 accumulation. The reduction in LOX2 levels caused no obvious changes in plant growth or in the accumulation of abscisic acid. However, the wound-induced accumulation of JA observed in control plants was absent in leaves of transgenic plants that lacked LOX2. Thus, LOX2 is required for the wound-induced synthesis of the plant growth regulator JA in leaves. We also examined the expression of a wound- and JA-inducible Arabidopsis gene, vsp, in transgenic and control plants. Leaves of transgenic plants lacking LOX2 accumulated less vsp mRNA than did control leaves in response to wounding. This result suggests that wound-induced JA (or some other LOX2-requiring component of the wound response pathway) is involved in the wound-induced regulation of this gene.

ACTION OF DIPHTHERIA TOXIN IN THE GUINEA PIG

Science.gov (United States)

Baseman, Joel B.; Pappenheimer, A. M.; Gill, D. M.; Harper, Annabel A.

1970-01-01

The blood clearance and distribution in the tissues of 125I after intravenous injection of small doses (1.5–5 MLD or 0.08–0.25 µg) of 125I-labeled diphtheria toxin has been followed in guinea pigs and rabbits and compared with the fate of equivalent amounts of injected 125I-labeled toxoid and bovine serum albumin. Toxoid disappeared most rapidly from the blood stream and label accumulated and was retained in liver, spleen, and especially in kidney. Both toxin and BSA behaved differently. Label was found widely distributed among all the organs except the nervous system and its rate of disappearance from the tissues paralleled its disappearance from the circulation. There was no evidence for any particular affinity of toxin for muscle tissue or for a "target" organ. Previous reports by others that toxin causes specific and selective impairment of protein synthesis in muscle tissue were not confirmed. On the contrary, both in guinea pigs and rabbits, a reduced rate of protein synthesis was observed in all tissues that had taken up the toxin label. In tissues removed from intoxicated animals of both species there was an associated reduction in aminoacyl transferase 2 content. It is concluded that the primary action of diphtheria toxin in the living animal is to effect the inactivation of aminoacyl transferase 2. The resulting inhibition in rate of protein synthesis leads to morphologic damage in all tissues reached by the toxin and ultimately to death of the animal. PMID:5511567

Cancer Stem-Like Cells Accumulated in Nickel-Induced Malignant Transformation

Science.gov (United States)

Wang, Lei; Fan, Jia; Hitron, John Andrew; Son, Young-Ok; Wise, James T.F.; Roy, Ram Vinod; Kim, Donghern; Dai, Jin; Pratheeshkumar, Poyil; Zhang, Zhuo; Shi, Xianglin

2016-01-01

Nickel compounds are known as human carcinogens. Chronic environmental exposure to nickel is a worldwide health concern. Although the mechanisms of nickel-induced carcinogenesis are not well understood, recent studies suggest that stem cells/cancer stem cells are likely important targets. This study examines the role of cancer stem cells in nickel-induced cell transformation. The nontransformed human bronchial epithelial cell line (Beas-2B) was chronically exposed to nickel chloride for 12 months to induce cell transformation. Nickel induced Beas-2B cell transformation, and cancer stem-like cells were enriched in nickel-transformed cell (BNiT) population. The BNiT cancer stem-like cells demonstrated enhanced self-renewal and distinctive differentiation properties. In vivo tumorigenesis studies show that BNiT cancer stem-like cells possess a high tumor-initiating capability. It was also demonstrated that superoxide dismutase 1 was involved in the accumulation of cancer stem-like cells; the regulation of superoxide dismutase 1 expression was different in transformed stem-like cells and nontransformed. Overall, the accumulation of stem-like cells and their enhanced stemness functions contribute to nickel-induced tumorigenesis. Our study provides additional insight into the mechanisms by which metals or other chemicals can induce carcinogenesis. PMID:26962057

Cyclic ADP-ribose and IP3 mediate abscisic acid-induced isoflavone accumulation in soybean sprouts

International Nuclear Information System (INIS)

Jiao, Caifeng; Yang, Runqiang; Gu, Zhenxin

2016-01-01

In this study, the roles of ABA-cADPR-Ca 2+ and ABA-IP3-Ca 2+ signaling pathways in UV-B-induced isoflavone accumulation in soybean sprouts were investigated. Results showed that abscisic acid (ABA) up regulated cyclic ADP-ribose (cADPR) and inositol 1,4,5-trisphosphate (IP3) levels in soybean sprouts under UV-B radiation. Furthermore, cADPR and IP3, as second messengers of UV-B-triggered ABA, induced isoflavone accumulation by up-regulating proteins and genes expression and activity of isoflavone biosynthetic-enzymes (chalcone synthase, CHS; isoflavone synthase, IFS). After Ca 2+ was chelated by EGTA, isoflavone content decreased. Overall, ABA-induced cADPR and IP3 up regulated isoflavone accumulation which was mediated by Ca 2+ signaling via enhancing the expression of proteins and genes participating in isoflavone biosynthesis in soybean sprouts under UV-B radiation. - Highlights: • UV-B-induced cADPR and IP3 synthesis was mediated by ABA. • cADPR and IP3 were involved in UV-B-ABA-induced isoflavone accumulation. • cADPR and IP3-induced isoflavone accumulation may be mediated by Ca 2+ . • ABA, cADPR, IP3 and Ca 2+ could activate proteins expression of CHS and IFS.

Accumulation of deuterium oxide in body fluids after ingestion of D2O-labeled beverages

International Nuclear Information System (INIS)

Davis, J.M.; Lamb, D.R.; Burgess, W.A.; Bartoli, W.P.

1987-01-01

A simple low-cost procedure was developed to compare the temporal profiles of deuterium oxide (D 2 O) accumulation in body fluids after ingestion of D 2 O-labeled solutions. D 2 O concentration was measured in plasma and saliva samples taken at various intervals after ingestion of 20 ml of D 2 O mixed with five solutions differing in carbohydrate and electrolyte concentrations. An infrared spectrometer was used to measure D 2 O in purified samples obtained after a 48-h incubation period during which the water (D 2 O and H 2 O) in the sample was equilibrated with an equal volume of distilled water in a sealed diffusion dish. The procedure yields 100% recoveries of 60-500 ppm D 2 O with an average precision of 5%. When compared with values for distilled water, D 2 O accumulation in serial samples of plasma and saliva was slower for ingested solutions containing 40 and 15% glucose and faster for hypotonic saline and a 6% carbohydrate-electrolyte solution. These differences appear to reflect known differences in gastric emptying and intestinal absorption of these beverages. Therefore, this technique may provide a useful index of the rate of water uptake from ingested beverages into the body fluids

Quercetin suppresses hypoxia-induced accumulation of hypoxia-inducible factor-1alpha (HIF-1alpha) through inhibiting protein synthesis.

Science.gov (United States)

Lee, Dae-Hee; Lee, Yong J

2008-10-01

Quercetin, a ubiquitous bioactive plant flavonoid, has been shown to inhibit the proliferation of cancer cells and induce the accumulation of hypoxia-inducible factor-1alpha (HIF-1alpha) in normoxia. In this study, under hypoxic conditions (1% O(2)), we examined the effect of quercetin on the intracellular level of HIF-1alpha and extracellular level of vascular endothelial growth factor (VEGF) in a variety of human cancer cell lines. Surprisingly, we observed that quercetin suppressed the HIF-1alpha accumulation during hypoxia in human prostate cancer LNCaP, colon cancer CX-1, and breast cancer SkBr3 cells. Quercetin treatment also significantly reduced hypoxia-induced secretion of VEGF. Suppression of HIF-1alpha accumulation during treatment with quercetin in hypoxia was not prevented by treatment with 26S proteasome inhibitor MG132 or PI3K inhibitor LY294002. Interestingly, hypoxia (1% O(2)) in the presence of 100 microM quercetin inhibited protein synthesis by 94% during incubation for 8 h. Significant quercetin concentration-dependent inhibition of protein synthesis and suppression of HIF-1alpha accumulation were observed under hypoxic conditions. Treatment with 100 microM cycloheximide, a protein synthesis inhibitor, replicated the effect of quercetin by inhibiting HIF-1alpha accumulation during hypoxia. These results suggest that suppression of HIF-1alpha accumulation during treatment with quercetin under hypoxic conditions is due to inhibition of protein synthesis. (c) 2008 Wiley-Liss, Inc.

Nanoporous biomaterials for uremic toxin adsorption in artificial kidney systems: A review.

Science.gov (United States)

Cheah, Wee-Keat; Ishikawa, Kunio; Othman, Radzali; Yeoh, Fei-Yee

2017-07-01

Hemodialysis, one of the earliest artificial kidney systems, removes uremic toxins via diffusion through a semipermeable porous membrane into the dialysate fluid. Miniaturization of the present hemodialysis system into a portable and wearable device to maintain continuous removal of uremic toxins would require that the amount of dialysate used within a closed-system is greatly reduced. Diffused uremic toxins within a closed-system dialysate need to be removed to maintain the optimum concentration gradient for continuous uremic toxin removal by the dialyzer. In this dialysate regenerative system, adsorption of uremic toxins by nanoporous biomaterials is essential. Throughout the years of artificial kidney development, activated carbon has been identified as a potential adsorbent for uremic toxins. Adsorption of uremic toxins necessitates nanoporous biomaterials, especially activated carbon. Nanoporous biomaterials are also utilized in hemoperfusion for uremic toxin removal. Further miniaturization of artificial kidney system and improvements on uremic toxin adsorption capacity would require high performance nanoporous biomaterials which possess not only higher surface area, controlled pore size, but also designed architecture or structure and surface functional groups. This article reviews on various nanoporous biomaterials used in current artificial kidney systems and several emerging nanoporous biomaterials. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1232-1240, 2017. © 2016 Wiley Periodicals, Inc.

Acetylation/deacetylation reactions of T-2, acetyl T-2, HT-2, and acetyl HT-2 toxins in bovine rumen fluid in vitro

International Nuclear Information System (INIS)

Munger, C.E.; Ivie, G.W.; Christopher, R.J.; Hammock, B.D.; Phillips, T.D.

1987-01-01

A tritiated preparation of the trichothecene mycotoxin, T-2 toxin, underwent both acetylation and deacetylation reactions when incubated with bovine rumen fluid in vitro. Products from incubations of T-2 in rumen fluid included acetyl T-2, HT-2, and acetyl HT-2. Direct studies with tritiated samples of each of these metabolites confirmed their relatively facile interconversion in the rumen. Studies with [ 3 H]HT-2 under conditions of inhibited esterase activity (added diisopropyl fluorophosphate) showed that acetylation is preferred at C-3 vs. C-4. Studies with [ 3 H]acetyl T-2 indicated that deacetylation similarly occurs with greater rapidity at C-3. There were no indications that ester hydrolysis of these trichothecenes occurred at C-8 or C-15 or that they were subjected to epoxide reduction reactions. These data suggest that acetylation of T-2 and other trichothecenes in the rumen in situ may ultimately result in the absorption of more lipophilic metabolites whose toxicological and residual properties are at present unknown

Spin Heat Accumulation Induced by Tunneling from a Ferromagnet

NARCIS (Netherlands)

Vera-Marun, I.J.; Wees, B.J. van; Jansen, R.

2014-01-01

An electric current from a ferromagnet into a nonmagnetic material can induce a spin-dependent electron temperature. Here, it is shown that this spin heat accumulation, when created by tunneling from a ferromagnet, produces a non-negligible voltage signal that is comparable to that due to the

Diphtheria toxin translocation across cellular membranes is regulated by sphingolipids

International Nuclear Information System (INIS)

Spilsberg, Bjorn; Hanada, Kentaro; Sandvig, Kirsten

2005-01-01

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 low 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

Saccharomyces boulardii Protease Inhibits the Effects of Clostridium difficile Toxins A and B in Human Colonic Mucosa

Science.gov (United States)

Castagliuolo, Ignazio; Riegler, Martin F.; Valenick, Leyla; LaMont, J. Thomas; Pothoulakis, Charalabos

1999-01-01

Saccharomyces boulardii is a nonpathogenic yeast used in the treatment of Clostridium difficile diarrhea and colitis. We have reported that S. boulardii inhibits C. difficile toxin A enteritis in rats by releasing a 54-kDa protease which digests the toxin A molecule and its brush border membrane (BBM) receptor (I. Castagliuolo, J. T. LaMont, S. T. Nikulasson, and C. Pothoulakis, Infect. Immun. 64:5225–5232, 1996). The aim of this study was to further evaluate the role of S. boulardii protease in preventing C. difficile toxin A enteritis in rat ileum and determine whether it protects human colonic mucosa from C. difficile toxins. A polyclonal rabbit antiserum raised against purified S. boulardii serine protease inhibited by 73% the proteolytic activity present in S. boulardii conditioned medium in vitro. The anti-protease immunoglobulin G (IgG) prevented the action of S. boulardii on toxin A-induced intestinal secretion and mucosal permeability to [3H]mannitol in rat ileal loops, while control rabbit IgG had no effect. The anti-protease IgG also prevented the effects of S. boulardii protease on digestion of toxins A and B and on binding of [3H]toxin A and [3H]toxin B to purified human colonic BBM. Purified S. boulardii protease reversed toxin A- and toxin B-induced inhibition of protein synthesis in human colonic (HT-29) cells. Furthermore, toxin A- and B-induced drops in transepithelial resistance in human colonic mucosa mounted in Ussing chambers were reversed by 60 and 68%, respectively, by preexposing the toxins to S. boulardii protease. We conclude that the protective effects of S. boulardii on C. difficile-induced inflammatory diarrhea in humans are due, at least in part, to proteolytic digestion of toxin A and B molecules by a secreted protease. PMID:9864230

Minimizing the Fluid Used to Induce Fracturing

Science.gov (United States)

Boyle, E. J.

2015-12-01

The less fluid injected to induce fracturing means less fluid needing to be produced before gas is produced. One method is to inject as fast as possible until the desired fracture length is obtained. Presented is an alternative injection strategy derived by applying optimal system control theory to the macroscopic mass balance. The picture is that the fracture is constant in aperture, fluid is injected at a controlled rate at the near end, and the fracture unzips at the far end until the desired length is obtained. The velocity of the fluid is governed by Darcy's law with larger permeability for flow along the fracture length. Fracture growth is monitored through micro-seismicity. Since the fluid is assumed to be incompressible, the rate at which fluid is injected is balanced by rate of fracture growth and rate of loss to bounding rock. Minimizing injected fluid loss to the bounding rock is the same as minimizing total injected fluid How to change the injection rate so as to minimize the total injected fluid is a problem in optimal control. For a given total length, the variation of the injected rate is determined by variations in overall time needed to obtain the desired fracture length, the length at any time, and the rate at which the fracture is growing at that time. Optimal control theory leads to a boundary condition and an ordinary differential equation in time whose solution is an injection protocol that minimizes the fluid used under the stated assumptions. That method is to monitor the rate at which the square of the fracture length is growing and adjust the injection rate proportionately.

/sup 125/I-labelled tetanus toxin as a neuronal marker in tissue cultures derived from embryonic CNS

Energy Technology Data Exchange (ETDEWEB)

Dimpfel, W; Neale, J H; Habermann, E [Giessen Univ. (F.R. Germany). Pharmakologisches Inst.; National Inst. of Child Health and Human Development, Bethesda, Md. (USA). Behavioural Biology Branch)

1975-01-01

Primary cultures derived from embryonic mouse brain and spinal cord were exposed to /sup 125/I-labelled tetanus toxin and subjected to autoradioraphy. Cells with neuronal, but not glial, morphology selectively accumulated the toxin. The distribution of the grains over these cells and their processes was not uniform, discrete processes showing heavier labelling.

Effect of Cryphonectria parasitica toxin on lipid peroxidation and ...

African Journals Online (AJOL)

Jane

2011-10-24

Oct 24, 2011 ... African Journal of Biotechnology Vol. 10(65) ... on membrane systems of the cells were lighter and they occurred later than expected in the resistant ..... Starch was accumulated normally in chloroplasts after Cp-toxin treatment and the starch inclusions continued to enlarge in all stages of treated leaves cells ...

Accumulation and elimination profiles of paralytic shellfish poison in the short-necked clam Tapes japonica fed with the toxic dinoflagellate Gymnodinium catenatum.

Science.gov (United States)

Samsur, Mohamad; Takatani, Tomohiro; Yamaguchi, Yasunaga; Sagara, Takefumi; Noguchi, Tamao; Arakawa, Osamu

2007-02-01

The paralytic shellfish poison (PSP)-producing dinoflagellate Gymnodinium catenatum (Gc) was fed to the short-necked clam Tapes japonica, and the accumulation, transformation and elimination profiles of PSP were investigated by means of high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC-FLD). The short-necked clams ingested most of the Gc cells (4 x 10(6) cells) supplied as a bolus at the beginning of the experiment, and accumulated a maximal amount of toxin (181 nmol/10 clams) after 12 hr. The rate of toxin accumulation at that time was 16%, which rapidly decreased thereafter. During the rearing period, a variation in toxin composition, derived presumably from the transformation of toxin analogues in the clams, was observed, including a reversal of the ratio of C2 to C1, and the appearance of carbamate (gonyautoxin (GTX) 2, 3) and decarbamoyl (dc) derivatives (decarbamoylsaxitoxin (dcSTX) and dcGTX2, 3), which were undetectable in Gc cells. The total amount of toxin contained in clams and residue (remaining Gc cells and/or excrement in the rearing tank) gradually declined, and only about 1% of the supplied toxin was detected at the end of the experiment.

Analysis of fluid induced vibration of cryogenic pipes in consideration of the cooling effect

International Nuclear Information System (INIS)

Kim, Bong Soo; Kim, Young Ki; Choi, Jung Woon

2008-01-01

The purpose of system analysis using fluid induced vibration is to identify the problems of the system in advance by analyzing the vibration behavior of the system excited by fluid flow. Fluid-induced vibration analysis methods, developed so far, generally use the numerical analysis method to analyze the fluid flowing inside the pipe and the infinitesimal elements at normal temperature on the basis of the governing equation obtained by applying Newton's Second Law and the momentum equation. However, as the fluid temperature changes greatly at low temperature, fluid-induced vibration analysis methods for normal temperature cannot be applied. This study investigated methods of analyzing fluid-induced vibration in consideration of the cooling effect. In consideration of the changes in the properties of the fluid and system relative to temperature, vibration behavior was analyzed numerically by means of the equation of motion. As a result, the natural frequency of the system tends to change because of the changes of the properties of materials even when the flux is constant inside the pipe, and the vibration behavior of the system was compared to that in case of normal temperature to analyze how much influence the cooling effect has on the vibration behavior of the system

Selenoprotein P Inhibits Radiation-Induced Late Reactive Oxygen Species Accumulation and Normal Cell Injury

Energy Technology Data Exchange (ETDEWEB)

Eckers, Jaimee C.; Kalen, Amanda L.; Xiao, Wusheng; Sarsour, Ehab H.; Goswami, Prabhat C., E-mail: prabhat-goswami@uiowa.edu

2013-11-01

Purpose: Radiation is a common mode of cancer therapy whose outcome is often limited because of normal tissue toxicity. We have shown previously that the accumulation of radiation-induced late reactive oxygen species (ROS) precedes cell death, suggesting that metabolic oxidative stress could regulate cellular radiation response. The purpose of this study was to investigate whether selenoprotein P (SEPP1), a major supplier of selenium to tissues and an antioxidant, regulates late ROS accumulation and toxicity in irradiated normal human fibroblasts (NHFs). Methods and Materials: Flow cytometry analysis of cell viability, cell cycle phase distribution, and dihydroethidium oxidation, along with clonogenic assays, were used to measure oxidative stress and toxicity. Human antioxidant mechanisms array and quantitative real-time polymerase chain reaction assays were used to measure gene expression during late ROS accumulation in irradiated NHFs. Sodium selenite addition and SEPP1 overexpression were used to determine the causality of SEPP1 regulating late ROS accumulation and toxicity in irradiated NHFs. Results: Irradiated NHFs showed late ROS accumulation (4.5-fold increase from control; P<.05) that occurs after activation of the cell cycle checkpoint pathways and precedes cell death. The mRNA levels of CuZn- and Mn-superoxide dismutase, catalase, peroxiredoxin 3, and thioredoxin reductase 1 increased approximately 2- to 3-fold, whereas mRNA levels of cold shock domain containing E1 and SEPP1 increased more than 6-fold (P<.05). The addition of sodium selenite before the radiation treatment suppressed toxicity (45%; P<.05). SEPP1 overexpression suppressed radiation-induced late ROS accumulation (35%; P<.05) and protected NHFs from radiation-induced toxicity (58%; P<.05). Conclusion: SEPP1 mitigates radiation-induced late ROS accumulation and normal cell injury.

The analysis of lipophilic marine toxins : development of an alternative method

NARCIS (Netherlands)

Gerssen, A.

2010-01-01

Lipophilic marine toxins are produced by certain algae species and can accumulate in filter feeding shellfish such as mussels, scallops and oysters. Consumption of contaminated shellfish can lead to severe intoxications such as diarrhea, abdominal cramps and vomiting. Methods described in

Assessing adverse effects of intra-articular botulinum toxin A in healthy Beagle dogs: A placebo-controlled, blinded, randomized trial.

Science.gov (United States)

Heikkilä, Helka M; Jokinen, Tarja S; Syrjä, Pernilla; Junnila, Jouni; Hielm-Björkman, Anna; Laitinen-Vapaavuori, Outi

2018-01-01

To investigate the clinical, cytological, and histopathological adverse effects of intra-articularly injected botulinum toxin A in dogs and to study whether the toxin spreads from the joint after the injection. A longitudinal, placebo-controlled, randomized clinical trial was conducted with six healthy laboratory Beagle dogs. Stifle joints were randomized to receive either 30 IU of onabotulinum toxin A or placebo in a 1:1 ratio. Adverse effects and spread of the toxin were examined by evaluating dynamic and static weight-bearing of the injected limbs, by assessing painless range of motion and pain on palpation of joints, and by performing synovial fluid analysis, neurological examination, and electrophysiological recordings at different examination time-points in a 12-week period after the injections. The dogs were then euthanized and autopsy and histopathological examination of joint structures and adjacent muscles and nerves were performed. Intra-articular botulinum toxin A did not cause local weakness or injection site pain. Instead, static weight-bearing and painless range of motion of stifle joints decreased in the placebo limbs. No clinically significant abnormalities associated with intra-articular botulinum toxin A were detected in the neurological examinations. Electrophysiological recordings showed low compound muscle action potentials in two dogs in the botulinum toxin A-injected limb. No significant changes were detected in the synovial fluid. Autopsy and histopathological examination of the joint and adjacent muscles and nerves did not reveal histopathological adverse effects of the toxin. Intra-articular botulinum toxin A does not produce significant clinical, cytological, or histopathological adverse effects in healthy dogs. Based on the electrophysiological recordings, the toxin may spread from the joint, but its clinical impact seems to be low.

Diagnosis of drowning using post-mortem computed tomography based on the volume and density of fluid accumulation in the maxillary and sphenoid sinuses.

Science.gov (United States)

Kawasumi, Yusuke; Kawabata, Tomoyoshi; Sugai, Yusuke; Usui, Akihito; Hosokai, Yoshiyuki; Sato, Miho; Saito, Haruo; Ishibashi, Tadashi; Hayashizaki, Yoshie; Funayama, Masato

2013-10-01

Recent studies have reported that drowning victims frequently have fluid accumulation in the paranasal sinuses, most notably the maxillary and sphenoid sinuses. However, in our previous study, many non-drowning victims also had fluid accumulation in the sinuses. Therefore, we evaluated the qualitative difference in fluid accumulation between drowning and non-drowning cases in the present study. Thirty-eight drowning and 73 non-drowning cases were investigated retrospectively. The fluid volume and density of each case were calculated using a DICOM workstation. The drowning cases were compared with the non-drowning cases using the Mann-Whitney U-test because the data showed non-normal distribution. The median fluid volume was 1.82 (range 0.02-11.7) ml in the drowning cases and 0.49 (0.03-8.7) ml in the non-drowning cases, and the median fluid density was 22 (-14 to 66) and 39 (-65 to 77) HU, respectively. Both volume and density differed significantly between the drowning and non-drowning cases (p=0.001, p=0.0007). Regarding cut-off levels in the ROC analysis, the points on the ROC curve closest (0, 1) were 1.03ml (sensitivity 68%, specificity 68%, PPV 53%, NPV 81%) and 27.5 HU (61%, 70%, 51%, 77%). The Youden indices were 1.03ml and 37.8 HU (84%, 51%, 47%, 86%). When the cut-off level was set at 1.03ml and 27.5HU, the sensitivity was 42%, specificity 45%, PPV 29% and NPV 60%. When the cut-off level was set at 1.03ml and 37.8HU, sensitivity was 58%, specificity 32%, PPV 31% and NPV 59%. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Cellular Uptake of the Clostridium perfringens Binary Iota-Toxin

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Blöcker, Dagmar; Behlke, Joachim; Aktories, Klaus; Barth, Holger

2001-01-01

The binary iota-toxin is produced by Clostridium perfringens type E strains and consists of two separate proteins, the binding component iota b (98 kDa) and an actin-ADP-ribosylating enzyme component iota a (47 kDa). Iota b binds to the cell surface receptor and mediates the translocation of iota a into the cytosol. Here we studied the cellular uptake of iota-toxin into Vero cells. Bafilomycin A1, but not brefeldin A or nocodazole, inhibited the cytotoxic effects of iota-toxin, indicating that toxin is translocated from an endosomal compartment into the cytoplasm. Acidification (pH ≤ 5.0) of the extracellular medium enabled iota a to directly enter the cytosol in the presence of iota b. Activation by chymotrypsin induced oligomerization of iota b in solution. An average mass of 530 ± 28 kDa for oligomers was determined by analytical ultracentrifugation, indicating heptamer formation. The entry of iota-toxin into polarized CaCo-2 cells was studied by measuring the decrease in transepithelial resistance after toxin treatment. Iota-toxin led to a significant decrease in resistance when it was applied to the basolateral surface of the cells but not following application to the apical surface, indicating a polarized localization of the iota-toxin receptor. PMID:11292715

Antiradiation Vaccine: Immunological neutralization of Radiation Toxins at Acute Radiation Syndromes.

Science.gov (United States)

Popov, Dmitri; Maliev, Slava

. Material and Methods: The SRD molecules were isolated from Lymphatic Systems of animals that were irradiated with high doses of irradiation and had a clinical and laboratory picture of the Cerebral Acute Radia-tion Syndrome, Cardiovascular Acute Radiation Syndrome, Gastrointestinal Acute Radiation Syndrome, and Hematological Acute Radiation Syndrome. Our classification of radiation tox-ins includes 4 major groups: 1.SRD-1, Cerebrovascular neurotoxic Radiation Toxins (CvARS); 2.SRD-2, Cardiovascular Radiation Toxins(CrARS); 3.SRD-3,Gastrointestinal neurotoxic Ra-diation Toxins (GiARS); 4.SRD-4, Hematopietic Radiation Toxins (HpARS). Radiation tox-ins possess both toxic and immunological properties. But mechanisms of immune-toxicity by which radiation toxins stimulate development of the ARS are poorly understood. We have studied lethal toxicity of radiation toxins and an ability of specific antibodies to neutralize toxic activity of radiation toxins by specific antibodies. Results: The Blocking Antiradiation Antibodies induce an immunologically specific effect and inhibiting effects on radiation induced neuro-toxicity, vascular-toxicity, gastrointestinal toxcity, hematopoietic toxicity. Antiradiation Antibodies prevent the radiation induced cytolysis of selected groups of cells that are sensitive to radiation. The Blocking Antiradiation Antibodies are immunologically specific and can be produced by immunization with the different radiation toxins isolated from irradiated mam-mals. We propose that Specific Antiradiation Antibodies targeted against the radiation induced Toxins. Specific Antiradiation Antibodies neutralize toxic properties of radiation toxins. Anti-radiation Antibodies in different phases of the Acute Radiation Syndromes can compete with cytotoxic lymphocytes and prevent cytolysis mediated by cytotoxic lymphocytes. Conclusions: Immunological inhibition of cytotoxic and neurotoxic properties of Specific Radiation Toxins are significant factors for improving

Serum Metabonomics of Articular Cartilage Destruction Induced by T-2 Toxin in Wistar Rats.

Science.gov (United States)

Zhu, Lei; Zhao, Zhi Jun; Ren, Xiao Bin; Li, Qiang; Ding, Hua; Sun, Zhou; Kao, Qing Jun; Wang, Li Hua

2018-01-01

The molecular pathogenesis of T-2 toxin-induced cartilage destruction has not been fully unraveled yet. The aim of this study was to detect changes in serum metabolites in a rat anomaly model with articular cartilage destruction. Thirty healthy male Wistar rats were fed a diet containing T-2 toxin (300 ng/kg chow) for 3 months. Histopathological changes in femorotibial cartilage were characterized in terms of chondrocyte degeneration/necrosis and superficial cartilage defect, and the endogenous metabolite profile of serum was determined by UPLC/Q-TOF MS. Treated rats showed extensive areas of chondrocyte necrosis and superficial cartilage defect in the articular cartilage. In addition, 8 metabolites were found to change significantly in these rats compared to the control group, including lysoPE (18:0/0:0), lysoPC(14:0), lysoPC[18:4 (6Z,9Z,12Z,15Z)], lysoPC[(16:1(9Z)], lysoPC(16:0), L-valine, hippuric acid, and asparaginyl-glycine. These 8 metabolites associated with cartilage injury are mainly involved in phospholipid and amino acid metabolic pathways. Copyright © 2018 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Kefir prevented excess fat accumulation in diet-induced obese mice.

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Choi, Jae-Woo; Kang, Hye Won; Lim, Won-Chul; Kim, Mi-Kyoung; Lee, In-Young; Cho, Hong-Yon

2017-05-01

Excessive body fat accumulation can result in obesity, which is a serious health concern. Kefir, a probiotic, has recently shown possible health benefits in fighting obesity. This study investigated the inhibitory effects of 0.1 and 0.2% kefir powder on fat accumulation in adipose and liver tissues of high-fat diet (HFD)-induced obese mice. Kefir reduced body weight and epididymal fat pad weight and decreased adipocyte diameters in HFD-induced obese mice. This was supported by decreased expression of genes related to adipogenesis and lipogenesis as well as reduced proinflammatory marker levels in epididymal fat. Along with reduced hepatic triacylglycerol concentrations and serum alanine transaminase and aspartate transaminase activities, genes related to lipogenesis and fatty acid oxidation were downregulated and upregulated, respectively, in liver tissue. Kefir also decreased serum triacylglycerol, total cholesterol, and low-density lipoprotein-cholesterol concentrations. Overall, kefir has the potential to prevent obesity.

Interfacial patterns in magnetorheological fluids: Azimuthal field-induced structures.

Science.gov (United States)

Dias, Eduardo O; Lira, Sérgio A; Miranda, José A

2015-08-01

Despite their practical and academic relevance, studies of interfacial pattern formation in confined magnetorheological (MR) fluids have been largely overlooked in the literature. In this work, we present a contribution to this soft matter research topic and investigate the emergence of interfacial instabilities when an inviscid, initially circular bubble of a Newtonian fluid is surrounded by a MR fluid in a Hele-Shaw cell apparatus. An externally applied, in-plane azimuthal magnetic field produced by a current-carrying wire induces interfacial disturbances at the two-fluid interface, and pattern-forming structures arise. Linear stability analysis, weakly nonlinear theory, and a vortex sheet approach are used to access early linear and intermediate nonlinear time regimes, as well as to determine stationary interfacial shapes at fully nonlinear stages.

Stool C difficile toxin

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... 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 ( ...

Adenovirus type 5 induces progression of quiescent rat cells into S phase without polyamine accumulation.

Science.gov (United States)

Cheetham, B F; Shaw, D C; Bellett, A J

1982-01-01

Adenovirus type 5 induces cellular DNA synthesis and thymidine kinase in quiescent rat cells but does not induce ornithine decarboxylase. We now show that unlike serum, adenovirus type 5 fails to induce S-adenosylmethionine decarboxylase or polyamine accumulation. The inhibition by methylglyoxal bis(guanylhydrazone) of the induction of thymidine kinase by adenovirus type 5 is probably unrelated to its effects on polyamine biosynthesis. Thus, induction of cellular thymidine kinase and DNA replication by adenovirus type 5 is uncoupled from polyamine accumulation. PMID:7177112

Nutrients Turned into Toxins: Microbiota Modulation of Nutrient Properties in Chronic Kidney Disease.

Science.gov (United States)

Fernandez-Prado, Raul; Esteras, Raquel; Perez-Gomez, Maria Vanessa; Gracia-Iguacel, Carolina; Gonzalez-Parra, Emilio; Sanz, Ana B; Ortiz, Alberto; Sanchez-Niño, Maria Dolores

2017-05-12

In chronic kidney disease (CKD), accumulation of uremic toxins is associated with an increased risk of death. Some uremic toxins are ingested with the diet, such as phosphate and star fruit-derived caramboxin. Others result from nutrient processing by gut microbiota, yielding precursors of uremic toxins or uremic toxins themselves. These nutrients include l-carnitine, choline/phosphatidylcholine, tryptophan and tyrosine, which are also sold over-the-counter as nutritional supplements. Physicians and patients alike should be aware that, in CKD patients, the use of these supplements may lead to potentially toxic effects. Unfortunately, most patients with CKD are not aware of their condition. Some of the dietary components may modify the gut microbiota, increasing the number of bacteria that process them to yield uremic toxins, such as trimethylamine N-Oxide (TMAO), p-cresyl sulfate, indoxyl sulfate and indole-3 acetic acid. Circulating levels of nutrient-derived uremic toxins are associated to increased risk of death and cardiovascular disease and there is evidence that this association may be causal. Future developments may include maneuvers to modify gut processing or absorption of these nutrients or derivatives to improve CKD patient outcomes.

Acetylation/deacetylation reactions of T-2, acetyl T-2, HT-2, and acetyl HT-2 toxins in bovine rumen fluid in vitro

Energy Technology Data Exchange (ETDEWEB)

Munger, C.E.; Ivie, G.W.; Christopher, R.J.; Hammock, B.D.; Phillips, T.D.

A tritiated preparation of the trichothecene mycotoxin, T-2 toxin, underwent both acetylation and deacetylation reactions when incubated with bovine rumen fluid in vitro. Products from incubations of T-2 in rumen fluid included acetyl T-2, HT-2, and acetyl HT-2. Direct studies with tritiated samples of each of these metabolites confirmed their relatively facile interconversion in the rumen. Studies with (/sup 3/H)HT-2 under conditions of inhibited esterase activity (added diisopropyl fluorophosphate) showed that acetylation is preferred at C-3 vs. C-4. Studies with (/sup 3/H)acetyl T-2 indicated that deacetylation similarly occurs with greater rapidity at C-3. There were no indications that ester hydrolysis of these trichothecenes occurred at C-8 or C-15 or that they were subjected to epoxide reduction reactions. These data suggest that acetylation of T-2 and other trichothecenes in the rumen in situ may ultimately result in the absorption of more lipophilic metabolites whose toxicological and residual properties are at present unknown.

Microfluidic device and methods for focusing fluid streams using electroosmotically induced pressures

Science.gov (United States)

Jacobson, Stephen C.; Ramsey, J. Michael

2010-06-01

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either electric current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to electrokinetically inducing fluid flow to confine a selected material in a region of a microchannel that is not influenced by an electric field. Other structures for inducing fluid flow in accordance with this invention include nanochannel bridging membranes and alternating current fluid pumping devices. Applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Fluid-induced vibration of composite natural gas pipelines

Energy Technology Data Exchange (ETDEWEB)

Zou, G.P.; Cheraghi, N.; Taheri, F. [Dalhousie Univ., Dept. of Civil Engineering, Halifax, NS (Canada)

2005-02-01

Advancements in materials bonding techniques have led to the use of reinforced composite pipelines. The use of steel pipe with a fiber-reinforced composite over-wrap together has produced an exceptionally strong pipe with positive advantages in weight and corrosion resistivity. Understanding the dynamic characteristics of this kind of sub-sea composite pipelines, which often accommodate axial flow of gas, and prediction of their response is of great interest. This paper presents a state-variable model developed for the analysis of fluid-induced vibration of composite pipeline systems. Simply supported, clamped and clamped-simply supported pipelines are investigated. The influence of fluid's Poisson ratio, the ratio of pipe radius to pipe-wall thickness, laminate layup, the ratio of liquid mass density to pipe-wall mass density, the fluid velocity, initial tension and fluid pressure are all considered. The results of our proposed methodology are compared with those of finite element analysis, using ANSYS ssoftware. (Author)

Decitabine induces delayed reactive oxygen species (ROS) accumulation in leukemia cells and induces the expression of ROS generating enzymes.

Science.gov (United States)

Fandy, Tamer E; Jiemjit, Anchalee; Thakar, Manjusha; Rhoden, Paulette; Suarez, Lauren; Gore, Steven D

2014-03-01

Azanucleoside DNA methyltransferase (DNMT) inhibitors are currently approved by the U.S. Food and Drug Administration for treatment of myelodysplastic syndrome. The relative contributions of DNMT inhibition and other off-target effects to their clinical efficacy remain unclear. Data correlating DNA methylation reversal and clinical response have been conflicting. Consequently, it is necessary to investigate so-called off-target effects and their impact on cell survival and differentiation. Flow cytometry was used for cell cycle, apoptosis, and reactive oxygen species (ROS) accumulation analysis. Gene expression analysis was performed using real-time PCR. DNA methylation was detected by methylation-specific PCR. Mitochondrial membrane potential was analyzed using JC-1 dye staining. Western blotting was used for quantitative protein expression analysis. 5-Aza-2'-deoxycytidine (DAC) induced cell-cycle arrest and apoptosis in leukemia cells. p53 expression was dispensable for DAC-induced apoptosis. DAC induced delayed ROS accumulation in leukemia cells but not in solid tumor cells and p53 expression was dispensable for ROS increase. ROS increase was deoxycytidine kinase dependent, indicating that incorporation of DAC into nuclear DNA is required for ROS generation. ROS accumulation by DAC was caspase-independent and mediated the dissipation of the mitochondrial membrane potential. Concordantly, ROS scavengers diminished DAC-induced apoptosis. DAC induced the expression of different NADPH oxidase isoforms and upregulated Nox4 protein expression in an ATM-dependent manner, indicating the involvement of DNA damage signaling in Nox4 upregulation. These data highlight the importance of mechanisms other than DNA cytosine demethylation in modulating gene expression and suggest investigating the relevance of ROS accumulation to the clinical activity of DAC. ©2014 AACR

Spin heat accumulation induced by tunneling from a ferromagnet.

Science.gov (United States)

Vera-Marun, I J; van Wees, B J; Jansen, R

2014-02-07

An electric current from a ferromagnet into a nonmagnetic material can induce a spin-dependent electron temperature. Here, it is shown that this spin heat accumulation, when created by tunneling from a ferromagnet, produces a non-negligible voltage signal that is comparable to that due to the coexisting electrical spin accumulation and can give a different Hanle spin precession signature. The effect is governed by the spin polarization of the Peltier coefficient of the tunnel contact, its Seebeck coefficient, and the spin heat resistance of the nonmagnetic material, which is related to the electrical spin resistance by a spin-Wiedemann-Franz law. Moreover, spin heat injection is subject to a heat conductivity mismatch that is overcome if the tunnel interface has a sufficiently large resistance.

Biooxidation of Ciguatoxins Leads to Species-Specific Toxin Profiles.

Science.gov (United States)

Ikehara, Tsuyoshi; Kuniyoshi, Kyoko; Oshiro, Naomasa; Yasumoto, Takeshi

2017-06-29

Ciguatoxins (CTXs) contaminate fish worldwide and cause the foodborne illness ciguatera. In the Pacific, these toxins are produced by the dinoflagellate Gambierdiscus toxicus , which accumulates in fish through the food chain and undergoes oxidative modification, giving rise to numerous analogs. In this study, we examined the oxidation of CTXs in vitro with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis using reference toxins, and found that CTX4A, CTX4B, and CTX3C, which are produced by the alga, are oxidized to the analogs found in fish, namely CTX1B, 52- epi -54-deoxyCTX1B, 54-deoxyCTX1B, 2-hydroxyCTX3C, and 2,3-dihydroxyCTX3C. This oxidation was catalyzed by human CYP3A4, fish liver S9 fractions, and microsomal fractions prepared from representative ciguateric fishes ( Lutjanus bohar , L. monostigumus , and Oplegnathus punctatus ). In addition, fish liver S9 fractions prepared from non-ciguateric fishes ( L. gibbus and L. fulviflamma ) in Okinawa also converted CTX4A and CTX4B to CTX1B, 54-deoxyCTX1B, and 52- epi -54-deoxyCTX1B in vitro. This is the first study to demonstrate the enzymatic oxidation of these toxins, and provides insight into the mechanism underlying the development of species-specific toxin profiles and the fate of these toxins in humans and fish.

rRNA fragmentation induced by a yeast killer toxin.

Science.gov (United States)

Kast, Alene; Klassen, Roland; Meinhardt, Friedhelm

2014-02-01

Virus like dsDNA elements (VLE) in yeast were previously shown to encode the killer toxins PaT and zymocin, which target distinct tRNA species via specific anticodon nuclease (ACNase) activities. Here, we characterize a third member of the VLE-encoded toxins, PiT from Pichia inositovora, and identify PiOrf4 as the cytotoxic subunit by conditional expression in Saccharomyces cerevisiae. In contrast to the tRNA targeting toxins, however, neither a change of the wobble uridine modification status by introduction of elp3 or trm9 mutations nor tRNA overexpression rescued from PiOrf4 toxicity. Consistent with a distinct RNA target, expression of PiOrf4 causes specific fragmentation of the 25S and 18S rRNA. A stable cleavage product comprising the first ∼ 130 nucleotides of the 18S rRNA was purified and characterized by linker ligation and subsequent reverse transcription; 3'-termini were mapped to nucleotide 131 and 132 of the 18S rRNA sequence, a region showing some similarity to the anticodon loop of tRNA(Glu)(UUC), the zymocin target. PiOrf4 residues Glu9 and His214, corresponding to catalytic sites Glu9 and His209 in the ACNase subunit of zymocin are essential for in vivo toxicity and rRNA fragmentation, raising the possibility of functionally conserved RNase modules in both proteins. © 2013 John Wiley & Sons Ltd.

Desiccation induces accumulations of antheraxanthin and zeaxanthin in intertidal macro-alga Ulva pertusa (Chlorophyta.

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Xiujun Xie

Full Text Available For plants and algae, exposure to high light levels is deleterious to their photosynthetic machineries. It also can accelerate water evaporation and thus potentially lead to drought stress. Most photosynthetic organisms protect themselves against high light caused photodamages by xanthophyll cycle-dependent thermal energy dissipation. It is generally accepted that high light activates xanthophyll cycle. However, the relationship between xanthophyll cycle and drought stress remains ambiguous. Herein, Ulva pertusa (Chlorophyta, a representative perennial intertidal macro-algae species with high drought-tolerant capabilities and simple structures, was used to investigate the operation of xanthophyll cycle during desiccation in air. The results indicate that desiccation under dim light induced accumulation of antheraxanthin (Ax and zeaxanthin (Zx at the expense of violaxanthin (Vx. This accumulation could be arrested by dithiothreitol completely and by uncoupler (carbonyl cyanide p-trifluoromethoxyphenylhydrazone partially, implying the participation of Vx de-epoxidase in conversion of Vx to Ax and Zx. Treatment with inhibitors of electron transport along thylakoid membrane, e.g. DCMU, PG and DBMIB, did not significantly arrest desiccation-induced accumulation of Ax and Zx. We propose that for U. pertusa, besides excess light, desiccation itself could also induce accumulation of Ax and Zx. This accumulation could proceed without electron transport along thylakoid membrane, and is possibly resulting from the reduction of thylakoid lumen volume during desiccation. Considering the pleiotropic effects of Ax and Zx, accumulated Ax and Zx may function in protecting thylakoid membrane and enhancing thermal quenching during emersion in air.

Computational fluid-dynamic model of laser-induced breakdown in air

International Nuclear Information System (INIS)

Dors, Ivan G.; Parigger, Christian G.

2003-01-01

Temperature and pressure profiles are computed by the use of a two-dimensional, axially symmetric, time-accurate computational fluid-dynamic model for nominal 10-ns optical breakdown laser pulses. The computational model includes a kinetics mechanism that implements plasma equilibrium kinetics in ionized regions and nonequilibrium, multistep, finite-rate reactions in nonionized regions. Fluid-physics phenomena following laser-induced breakdown are recorded with high-speed shadowgraph techniques. The predicted fluid phenomena are shown by direct comparison with experimental records to agree with the flow patterns that are characteristic of laser spark decay

Quiescent complement in nonhuman primates during E coli Shiga toxin-induced hemolytic uremic syndrome and thrombotic microangiopathy.

Science.gov (United States)

Lee, Benjamin C; Mayer, Chad L; Leibowitz, Caitlin S; Stearns-Kurosawa, D J; Kurosawa, Shinichiro

2013-08-01

Enterohemorrhagic Escherichia coli (EHEC) produce ribosome-inactivating Shiga toxins (Stx1, Stx2) responsible for development of hemolytic uremic syndrome (HUS) and acute kidney injury (AKI). Some patients show complement activation during EHEC infection, raising the possibility of therapeutic targeting of complement for relief. Our juvenile nonhuman primate (Papio baboons) models of endotoxin-free Stx challenge exhibit full spectrum HUS, including thrombocytopenia, hemolytic anemia, and AKI with glomerular thrombotic microangiopathy. There were no significant increases in soluble terminal complement complex (C5b-9) levels after challenge with lethal Stx1 (n = 6) or Stx2 (n = 5) in plasma samples from T0 to euthanasia at 49.5 to 128 hours post-challenge. d-dimer and cell injury markers (HMGB1, histones) confirmed coagulopathy and cell injury. Thus, complement activation is not required for the development of thrombotic microangiopathy and HUS induced by EHEC Shiga toxins in these preclinical models, and benefits or risks of complement inhibition should be studied further for this infection.

The Wor1-like protein Fgp1 regulates pathogenicity, toxin synthesis and reproduction in the phytopathogenic fungus Fusarium graminearum.

Directory of Open Access Journals (Sweden)

Wilfried Jonkers

Full Text Available WOR1 is a gene for a conserved fungal regulatory protein controlling the dimorphic switch and pathogenicity determents in Candida albicans and its ortholog in the plant pathogen Fusarium oxysporum, called SGE1, is required for pathogenicity and expression of key plant effector proteins. F. graminearum, an important pathogen of cereals, is not known to employ switching and no effector proteins from F. graminearum have been found to date that are required for infection. In this study, the potential role of the WOR1-like gene in pathogenesis was tested in this toxigenic fungus. Deletion of the WOR1 ortholog (called FGP1 in F. graminearum results in greatly reduced pathogenicity and loss of trichothecene toxin accumulation in infected wheat plants and in vitro. The loss of toxin accumulation alone may be sufficient to explain the loss of pathogenicity to wheat. Under toxin-inducing conditions, expression of genes for trichothecene biosynthesis and many other genes are not detected or detected at lower levels in Δfgp1 strains. FGP1 is also involved in the developmental processes of conidium formation and sexual reproduction and modulates a morphological change that accompanies mycotoxin production in vitro. The Wor1-like proteins in Fusarium species have highly conserved N-terminal regions and remarkably divergent C-termini. Interchanging the N- and C- terminal portions of proteins from F. oxysporum and F. graminearum resulted in partial to complete loss of function. Wor1-like proteins are conserved but have evolved to regulate pathogenicity in a range of fungi, likely by adaptations to the C-terminal portion of the protein.

Bt rice harbouring cry genes controlled by a constitutive or wound-inducible promoter: protection and transgene expression under Mediterranean field conditions.

Science.gov (United States)

Breitler, Jean Christophe; Vassal, Jean Michel; del Mar Catala, Maria; Meynard, Donaldo; Marfà, Victoria; Melé, Enric; Royer, Monique; Murillo, Isabel; San Segundo, Blanca; Guiderdoni, Emmanuel; Messeguer, Joaquima

2004-09-01

Seven homozygous transgenic lines of two European commercial cultivars of rice (Ariete (A) and Senia (S)), harbouring the cry1B or cry1Aa Bacillus thuringiensis (Bt) delta-endotoxin genes, were field evaluated for protection from striped stem borer (SSB) (Chilo suppressalis) damage during the 2001 and 2002 summer crop seasons in the Delta de l'Ebre region, Spain. The plant codon-optimized toxin gene was placed under the control of the promoter of either the constitutive ubi1 gene or the wound-inducible mpi gene from maize. Stable, high-level, insecticidal protein accumulation was observed throughout root, leaf and seed tissues of field-grown plants harbouring the cry1B (lines A64.1, A33.1, A3.4 and S98.9) or cry1Aa (lines S05.1 and A19.14) genes under the control of the ubi1 promoter. Conversely, no toxin was detected in unwounded vegetative tissues of the A9.1 line harbouring the cry1B gene controlled by the mpi promoter, indicating that natural environmental stresses did not trigger the activity of the wound-inducible promoter. However, the toxin accumulated at 0.2% total soluble proteins in A9.1 sheath tissue exhibiting brown lesions resulting from SSB damage. The agronomical traits and performance of the transgenic lines were generally comparable with parental controls, except in the two lines accumulating Cry1Aa, which exhibited a high frequency of plants non-true to type. Natural infestation was assisted with manual infestations of L2/L3 SSB larvae in border control plants surrounding the experimental plots, which served as a reservoir for the second-cycle SSB population. The observation of damage (brown lesions and dead hearts) during the crop season and dissection of plants at harvest stage revealed a range of protection amongst the transgenic lines, which was highly consistent with the level of toxin accumulation and with previous experience in greenhouse assays. Lines A3.4 and S05.1 were found to exhibit stable and full protection against SSB attacks

Inhibition of cholera toxin and other AB toxins by polyphenolic compounds

Science.gov (United States)

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...

Platelet cytosolic 44-kDa protein is a substrate of cholera toxin-induced ADP-ribosylation and is not recognized by antisera against the α subunit of the stimulatory guanine nucleotide-binding regulatory protein

International Nuclear Information System (INIS)

Molina Y Vedia, L.M.; Reep, B.R.; Lapetina, E.G.

1988-01-01

ADP-ribosylation induced by cholera toxin and pertussis toxin was studied in particulate and cytosolic fractions of human platelets. Platelets were disrupted by a cycle of freezing and thawing in the presence of a hyposmotic buffer containing protease inhibitors. In both fractions, the A subunit of cholera toxin ADP-ribosylates two proteins with molecular masses of 42 and 44 kDa, whereas pertussis toxin ADP-ribosylates a 41-kDa polypeptide. Two antisera against the α subunit of the stimulatory guanine nucleotide-binding regulatory protein recognize only the 42-kDa polypeptide. Cholera toxin-induced ADP-ribosylation of the 42- and 44-kDa proteins is reduced by pretreatment of platelets with iloprost, a prostacyclin analog. The 44-kDa protein, which is substrate of cholera toxin, could be extracted completely from the membrane and recovered in the cytosolic fraction when the cells were disrupted by Dounce homogenization and the pellet was extensively washed. A 44-kDa protein can also be labeled with 8-azidoguanosine 5'-[α- 32 P]triphosphate in the cytosol and membranes. These finding indicate that cholera and pertussis toxins produced covalent modifications of proteins present in particulate and cytosolic platelet fractions. Moreover, the 44-kDa protein might be an α subunit of a guanine nucleotide-binding regulatory protein that is not recognized by available antisera

Self-protection of Pseudomonas syringae pv. tabaci from its toxin, tabtoxinine-β-lactam

International Nuclear Information System (INIS)

Knight, T.J.; Durbin, R.D.; Langston-Unkefer, P.J.

1987-01-01

An extracellular toxin, tabtoxinine-β-lactam (TβL), is produced by Pseudomonas syringae pv. tabaci. This toxin irreversibly inhibits its target, glutamine synthetase; yet P. syringae pv. tabaci retains significant amounts of glutamine synthetase activity during toxin production in culture. As part of our investigation of the self-protection of P. syringae pv. tabaci, the authors compared the effects of TβL on Tox + (TβL-producing, insensitive to TβL) and Tox - (TβL nonproducing, sensitive to TΛ) strains. The extent of protection afforded to the Tox - strain when induced to adenylylate glutamine synthetase was tested. It was concluded that an additional protection mechanism was required. A detoxification activity was found in the Tox + strain which opens the ε-lactam ring to TβL to produce the inactive, open-chain form, tabtoxinine. Whole cells of the Tox + strain incubated for 24 h with [ 14 C]TβL (0.276 μmol/3 x 10 10 cells) contained [ 14 C]tabtoxinine (0.056 μmol), and the medium contained TβL (0.226 μmol). Extracts of spheroplasts of the Tox + stain also converted TβL to tabtoxinine, whereas extracts of the Tox - strain did not alter TβL. The conversion was time dependent and stoichiometric and was destroyed by boiling for 30 min or by the addition of 5mM EDTA. Penicillin, a possible substrate and competitive inhibitor of this lactamase activity, inhibited the conversion of TΛ to tabtoxinine. Periplasmic fluid did not catalyze the conversion of TβL

Laboratory simulations of fluid/gas induced micro-earthquakes: application to volcano seismology.

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Philip Michael Benson

2014-11-01

Full Text Available Understanding different seismic signals recorded in active volcanic regions allows geoscientists to derive insight into the processes that generate them. A key type is known as Low Frequency or Long Period (LP event, generally understood to be generated by different fluid types resonating in cracks and faults. The physical mechanisms of these signals have been linked to either resonance/turbulence within fluids, or as a result of fluids ‘sloshing’ due to a mixture of gas and fluid being present in the system. Less well understood, however, is the effect of the fluid type (phase on the measured signal. To explore this, we designed an experiment in which we generated a precisely controlled liquid to gas transition in a closed system by inducing rapid decompression of fluid-filled fault zones in a sample of basalt from Mt. Etna Volcano, Italy. We find that fluid phase transition is accompanied by a marked frequency shift in the accompanying microseismic dataset that can be compared to volcano seismic data. Moreover, our induced seismic activity occurs at pressure conditions equivalent to hydrostatic depths of 200 to 750 meters. This is consistent with recently measured dominant frequencies of LP events and with numerous models.

INFLUENCE OF THERMOHALINE CONVECTION ON DIFFUSION-INDUCED IRON ACCUMULATION IN A STARS

International Nuclear Information System (INIS)

Theado, S.; Vauclair, S.; Alecian, G.; LeBlanc, F.

2009-01-01

Atomic diffusion may lead to heavy-element accumulation inside stars in certain specific layers. Iron accumulation in the Z-bump opacity region has been invoked by several authors to quantitatively account for abundance anomalies observed in some stars, or to account for stellar oscillations through the induced κ-mechanism. These authors, however, never took into account the fact that such an accumulation creates an inverse μ-gradient, unstable for thermohaline convection. Here, we present results for A-F stars, where abundance variations are computed with and without this process. We show that iron accumulation is still present when thermohaline convection is taken into account, but much reduced compared to when this physical process is neglected. The consequences of thermohaline convection for A-type stars as well as for other types of stars are presented.

Protection of Human Podocytes from Shiga Toxin 2-Induced Phosphorylation of Mitogen-Activated Protein Kinases and Apoptosis by Human Serum Amyloid P Component

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Dettmar, Anne K.; Binder, Elisabeth; Greiner, Friederike R.; Liebau, Max C.; Kurschat, Christine E.; Jungraithmayr, Therese C.; Saleem, Moin A.; Schmitt, Claus-Peter; Feifel, Elisabeth; Orth-Höller, Dorothea; Kemper, Markus J.; Pepys, Mark; Würzner, Reinhard

2014-01-01

Hemolytic uremic syndrome (HUS) is mainly induced by Shiga toxin 2 (Stx2)-producing Escherichia coli. Proteinuria can occur in the early phase of the disease, and its persistence determines the renal prognosis. Stx2 may injure podocytes and induce proteinuria. Human serum amyloid P component (SAP), a member of the pentraxin family, has been shown to protect against Stx2-induced lethality in mice in vivo, presumably by specific binding to the toxin. We therefore tested the hypothesis that SAP can protect against Stx2-induced injury of human podocytes. To elucidate the mechanisms underlying podocyte injury in HUS-associated proteinuria, we assessed Stx2-induced activation of mitogen-activated protein kinases (MAPKs) and apoptosis in immortalized human podocytes and evaluated the impact of SAP on Stx2-induced damage. Human podocytes express Stx2-binding globotriaosylceramide 3. Stx2 applied to cultured podocytes was internalized and then activated p38α MAPK and c-Jun N-terminal kinase (JNK), important signaling steps in cell differentiation and apoptosis. Stx2 also activated caspase 3, resulting in an increased level of apoptosis. Coincubation of podocytes with SAP and Stx2 mitigated the effects of Stx2 and induced upregulation of antiapoptotic Bcl2. These data suggest that podocytes are a target of Stx2 and that SAP protects podocytes against Stx2-induced injury. SAP may therefore be a useful therapeutic option. PMID:24566618

Effect of chitosan-N-acetylcysteine conjugate in a mouse model of botulinum toxin B-induced dry eye.

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Hongyok, Teeravee; Chae, Jemin J; Shin, Young Joo; Na, Daero; Li, Li; Chuck, Roy S

2009-04-01

To evaluate the effect of a thiolated polymer lubricant, chitosan-N-acetylcysteine conjugate (C-NAC), in a mouse model of dry eye. Eye drops containing 0.5% C-NAC, 0.3% C-NAC, a vehicle (control group), artificial tears, or fluorometholone were applied in a masked fashion in a mouse model of induced dry eye from 3 days to 4 weeks after botulinum toxin B injection. Corneal fluorescein staining was periodically recorded. Real-time reverse transcriptase-polymerase chain reaction and immunofluorescence staining were performed at the end of the study to evaluate inflammatory cytokine expressions. Mice treated with C-NAC, 0.5%, and fluorometholone showed a downward trend that was not statistically significant in corneal staining compared with the other groups. Chitosan-NAC formulations, fluorometholone, and artificial tears significantly decreased IL-1beta (interleukin 1beta), IL-10, IL-12alpha, and tumor necrosis factor alpha expression in ocular surface tissues. The botulinum toxin B-induced dry eye mouse model is potentially useful in evaluating new dry eye treatment. Evaluation of important molecular biomarkers suggests that C-NAC may impart some protective ocular surface properties. However, clinical data did not indicate statistically significant improvement of tear production and corneal staining in any of the groups tested. Topically applied C-NAC might protect the ocular surface in dry eye syndrome, as evidenced by decreased inflammatory cytokine expression.

CD28: Direct and Critical Receptor for Superantigen Toxins

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Ziv Rotfogel

2013-09-01

Full Text Available Every adaptive immune response requires costimulation through the B7/CD28 axis, with CD28 on T-cells functioning as principal costimulatory receptor. Staphylococcal and streptococcal superantigen toxins hyperstimulate the T-cell-mediated immune response by orders of magnitude, inducing a lethal cytokine storm. We show that to elicit an inflammatory cytokine storm and lethality, superantigens must bind directly to CD28. Blocking access of the superantigen to its CD28 receptor with peptides mimicking the contact domains in either toxin or CD28 suffices to protect mice effectively from lethal shock. Our finding that CD28 is a direct receptor of superantigen toxins broadens the scope of microbial pathogen recognition mechanisms.

Binding of ATP by pertussis toxin and isolated toxin subunits

International Nuclear Information System (INIS)

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

1990-01-01

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 [ 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 [ 3 H]ATP to pertussis toxin in a competitive manner; 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 [ 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

Binding of ATP by pertussis toxin and isolated toxin subunits

Energy Technology Data Exchange (ETDEWEB)

Hausman, S.Z.; Manclark, C.R.; Burns, D.L. (Center for Biologics Evaluation and Research, Bethesda, MD (USA))

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; 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.

Giardia duodenalis infection reduces granulocyte infiltration in an in vivo model of bacterial toxin-induced colitis and attenuates inflammation in human intestinal tissue.

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James A Cotton

Full Text Available Giardia duodenalis (syn. G. intestinalis, G. lamblia is a predominant cause of waterborne diarrheal disease that may lead to post-infectious functional gastrointestinal disorders. Although Giardia-infected individuals could carry as much as 106 trophozoites per centimetre of gut, their intestinal mucosa is devoid of overt signs of inflammation. Recent studies have shown that in endemic countries where bacterial infectious diseases are common, Giardia infections can protect against the development of diarrheal disease and fever. Conversely, separate observations have indicated Giardia infections may enhance the severity of diarrheal disease from a co-infecting pathogen. Polymorphonuclear leukocytes or neutrophils (PMNs are granulocytic, innate immune cells characteristic of acute intestinal inflammatory responses against bacterial pathogens that contribute to the development of diarrheal disease following recruitment into intestinal tissues. Giardia cathepsin B cysteine proteases have been shown to attenuate PMN chemotaxis towards IL-8/CXCL8, suggesting Giardia targets PMN accumulation. However, the ability of Giardia infections to attenuate PMN accumulation in vivo and how in turn this effect may alter the host inflammatory response in the intestine has yet to be demonstrated. Herein, we report that Giardia infection attenuates granulocyte tissue infiltration induced by intra-rectal instillation of Clostridium difficile toxin A and B in an isolate-dependent manner. This attenuation of granulocyte infiltration into colonic tissues paralled decreased expression of several cytokines associated with the recruitment of PMNs. Giardia trophozoite isolates that attenuated granulocyte infiltration in vivo also decreased protein expression of cytokines released from inflamed mucosal biopsy tissues collected from patients with active Crohn's disease, including several cytokines associated with PMN recruitment. These results demonstrate for the first time

Free cholesterol accumulation impairs antioxidant activities and aggravates apoptotic cell death in menadione-induced oxidative injury.

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Lee, Waisin; Xu, Mingjing; Li, Yue; Gu, Yong; Chen, Jianping; Wong, Derek; Fung, Peter C W; Shen, Jiangang

2011-10-01

Although the relationship between hypercholesterolemia and oxidative stress has been extensively investigated, direct evidence regarding to the roles of cholesterol accumulation in the generations of reactive oxygen species (ROS) and apoptotic cell death under oxidative stress is lack. In this study, we investigated productions of superoxide anions (O(2)(-)) and nitric oxide (NO), and apoptotic cell death in wild type Chinese hamster ovary (CHO) cells and cholesterol accumulated CHO cells genetically and chemically. Oxidative stress was induced by menadione challenge. The results revealed that abundance of free cholesterol (FC) promoted menadione-induced O(2)(-) and NO productions. FC accumulation down-regulated eNOS expression but up-regulated NADPH oxidases, and inhibited the activities of superoxide dismutase (SOD) and catalase. Treatment of menadione increased the expressions of iNOS and qp91 phox, enhanced the activities of SOD and catalase in the wild-type CHO cells but inhibited the activity of glutathione peroxidase in the cholesterol accumulated CHO cells. Moreover, FC abundance promoted apoptotic cell death in these cells. Taken together, those results suggest that free cholesterol accumulation aggravates menadione-induced oxidative stress and exacerbates apoptotic cell death. Copyright © 2011 Elsevier Inc. All rights reserved.

A Study To Assess the Numbers and Prevalence of Bacillus cereus and Its Toxins in Pasteurized Fluid Milk.

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Saleh-Lakha, Saleema; Leon-Velarde, Carlos G; Chen, Shu; Lee, Susan; Shannon, Kelly; Fabri, Martha; Downing, Gavin; Keown, Bruce

2017-07-01

Bacillus cereus is a pathogenic adulterant of raw milk and can persist as spores and grow in pasteurized milk. The objective of this study was to determine the prevalence of B. cereus and its enterotoxins in pasteurized milk at its best-before date when stored at 4, 7, and 10°C. More than 5.5% of moderately temperature-abused products (stored at 7°C) were found to contain >10 5 CFU/mL B. cereus , and about 4% of them contained enterotoxins at a level that may result in foodborne illness; in addition, more than 31% of the products contained >10 5 CFU/mL B. cereus and associated enterotoxins when stored at 10°C. Results from a growth kinetic study demonstrated that enterotoxin production by B. cereus in pasteurized milk can occur in as short as 7 to 8 days of storage at 7°C. The higher B. cereus counts were associated with products containing higher butterfat content or with those produced using the conventional high-temperature, short-time pasteurization process. Traditional indicators, aerobic colony counts and psychrotrophic counts, were found to have no correlation with level of B. cereus in milk. The characterization of 17 representative B. cereus isolates from pasteurized milk revealed five toxigenic gene patterns, with all the strains carrying genes encoding for diarrheal toxins but not for an emetic toxin, and with one strain containing all four diarrheal enterotoxin genes (nheA, entFM, hblC, and cytK). The results of this study demonstrate the risks associated even with moderately temperature-abused pasteurized milk and the necessity of a controlled cold chain throughout the shelf life of fluid milk to enhance product safety and minimize foodborne illness.

Co-administration of cholera toxin and apple polyphenol extract as a novel and safe mucosal adjuvant strategy.

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Yoshino, Naoto; Fujihashi, Kohtaro; Hagiwara, Yukari; Kanno, Hiroyuki; Takahashi, Kiyomi; Kobayashi, Ryoki; Inaba, Noriyuki; Noda, Masatoshi; Sato, Shigehiro

2009-07-30

Although native cholera toxin (CT) is an extremely effective adjuvant, its toxicity prevents its use in humans. We report here that apple polyphenol extract (APE), obtained from unripe apples, reduces CT-induced morphological changes and cAMP accumulation. Based upon this finding, we have attempted to design a novel, effective and safe mucosal vaccine by using CT with several dosages of APE as nasal adjuvants. Mice nasally immunized with OVA plus CT and an optimal dosage of APE showed significantly reduced levels of inflammatory responses as well as total and OVA-specific IgE antibodies when compared with mice given without APE. However, levels of both mucosal and systemic OVA-specific antibody responses were maintained. Further, APE significantly down-regulated accumulation of CT in the olfactory nerves and epithelium. In summary, an optimal dosage of APE would take full advantage of mucosal adjuvanticity of native CT without any toxicity for application in humans.

Reactive oxygen species and hormone signaling cascades in endophytic bacterium induced essential oil accumulation in Atractylodes lancea.

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Zhou, Jia-Yu; Li, Xia; Zhao, Dan; Deng-Wang, Meng-Yao; Dai, Chuan-Chao

2016-09-01

Pseudomonas fluorescens induces gibberellin and ethylene signaling via hydrogen peroxide in planta . Ethylene activates abscisic acid signaling. Hormones increase sesquiterpenoid biosynthesis gene expression and enzyme activity, inducing essential oil accumulation. Atractylodes lancea is a famous Chinese medicinal plant, whose main active components are essential oils. Wild A. lancea has become endangered due to habitat destruction and over-exploitation. Although cultivation can ensure production of the medicinal material, the essential oil content in cultivated A. lancea is significantly lower than that in the wild herb. The application of microbes as elicitors has become an effective strategy to increase essential oil accumulation in cultivated A. lancea. Our previous study identified an endophytic bacterium, Pseudomonas fluorescens ALEB7B, which can increase essential oil accumulation in A. lancea more efficiently than other endophytes; however, the underlying mechanisms remain unknown (Physiol Plantarum 153:30-42, 2015; Appl Environ Microb 82:1577-1585, 2016). This study demonstrates that P. fluorescens ALEB7B firstly induces hydrogen peroxide (H2O2) signaling in A. lancea, which then simultaneously activates gibberellin (GA) and ethylene (ET) signaling. Subsequently, ET activates abscisic acid (ABA) signaling. GA and ABA signaling increase expression of HMGR and DXR, which encode key enzymes involved in sesquiterpenoid biosynthesis, leading to increased levels of the corresponding enzymes and then an accumulation of essential oils. Specific reactive oxygen species and hormone signaling cascades induced by P. fluorescens ALEB7B may contribute to high-efficiency essential oil accumulation in A. lancea. Illustrating the regulation mechanisms underlying P. fluorescens ALEB7B-induced essential oil accumulation not only provides the theoretical basis for the inducible synthesis of terpenoids in many medicinal plants, but also further reveals the complex and diverse

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

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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.

Genotoxicity and potential carcinogenicity of cyanobacterial toxins - a review.

Science.gov (United States)

Zegura, Bojana; Straser, Alja; Filipič, Metka

2011-01-01

The occurrence of cyanobacterial blooms has increased significantly in many regions of the world in the last century due to water eutrophication. These blooms are hazardous to humans, animals, and plants due to the production of cyanotoxins, which can be classified in five different groups: hepatotoxins, neurotoxins, cytotoxins, dermatotoxins, and irritant toxins (lipopolysaccharides). There is evidence that certain cyanobacterial toxins are genotoxic and carcinogenic; however, the mechanisms of their potential carcinogenicity are not well understood. The most frequently occurring and widespread cyanotoxins in brackish and freshwater blooms are the cyclic heptapeptides, i.e., microcystins (MCs), and the pentapeptides, i.e., nodularins (NODs). The main mechanism associated with potential carcinogenic activity of MCs and NOD is the inhibition of protein phosphatases, which leads to the hyperphosphorylation of cellular proteins, which is considered to be associated with their tumor-promoting activity. Apart from this, MCs and NOD induce increased formation of reactive oxygen species and, consequently, oxidative DNA damage. There is also evidence that MCs and NOD induce micronuclei, and NOD was shown to have aneugenic activity. Both cyanotoxins interfere with DNA damage repair pathways, which, along with DNA damage, is an important factor involved in the carcinogenicity of these agents. Furthermore, these toxins increase the expression of TNF-α and early-response genes, including proto-oncogenes, genes involved in the response to DNA damage, cell cycle arrest, and apoptosis. Rodent studies indicate that MCs and NOD are tumor promotors, whereas NOD is thought to have also tumor-initiating activity. Another cyanobacterial toxin, cylindrospermopsin (CYN), which has been neglected for a long time, is lately being increasingly found in the freshwater environment. The principal mechanism of its toxicity is the irreversible inhibition of protein synthesis. It is pro

Adenylate Cyclase Toxin promotes bacterial internalisation into non phagocytic cells.

Science.gov (United States)

Martín, César; Etxaniz, Asier; Uribe, Kepa B; Etxebarria, Aitor; González-Bullón, David; Arlucea, Jon; Goñi, Félix M; Aréchaga, Juan; Ostolaza, Helena

2015-09-08

Bordetella pertussis causes whooping cough, a respiratory infectious disease that is the fifth largest cause of vaccine-preventable death in infants. Though historically considered an extracellular pathogen, this bacterium has been detected both in vitro and in vivo inside phagocytic and non-phagocytic cells. However the precise mechanism used by B. pertussis for cell entry, or the putative bacterial factors involved, are not fully elucidated. Here we find that adenylate cyclase toxin (ACT), one of the important toxins of B. pertussis, is sufficient to promote bacterial internalisation into non-phagocytic cells. After characterization of the entry route we show that uptake of "toxin-coated bacteria" proceeds via a clathrin-independent, caveolae-dependent entry pathway, allowing the internalised bacteria to survive within the cells. Intracellular bacteria were found inside non-acidic endosomes with high sphingomyelin and cholesterol content, or "free" in the cytosol of the invaded cells, suggesting that the ACT-induced bacterial uptake may not proceed through formation of late endolysosomes. Activation of Tyr kinases and toxin-induced Ca(2+)-influx are essential for the entry process. We hypothesize that B. pertussis might use ACT to activate the endocytic machinery of non-phagocytic cells and gain entry into these cells, in this way evading the host immune system.

Bladder-type hydropneumatic accumulators

International Nuclear Information System (INIS)

Anigas, F.

1985-01-01

Hydropneumatic pressure accumulators allow liquids to be stored under pressure, their operating principle being based on the inherent compressibility of elements in a liquid and gaseous state. A wide range of fluids can be covered by means of the appropriate choice of the material for the body and bladder. Their main applications are: energy accumulation, safety reserve, suspension. (author)

Abscisic acid-regulated protein degradation causes osmotic stress-induced accumulation of branched-chain amino acids in Arabidopsis thaliana.

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Huang, Tengfang; Jander, Georg

2017-10-01

Whereas proline accumulates through de novo biosynthesis in plants subjected to osmotic stress, leucine, isoleucine, and valine accumulation in drought-stressed Arabidopsis thaliana is caused by abscisic acid-regulated protein degradation. In response to several kinds of abiotic stress, plants greatly increase their accumulation of free amino acids. Although stress-induced proline increases have been studied the most extensively, the fold-increase of other amino acids, in particular branched-chain amino acids (BCAAs; leucine, isoleucine, and valine), is often higher than that of proline. In Arabidopsis thaliana (Arabidopsis), BCAAs accumulate in response to drought, salt, mannitol, polyethylene glycol, herbicide treatment, and nitrogen starvation. Plants that are deficient in abscisic acid signaling accumulate lower amounts of BCAAs, but not proline and most other amino acids. Previous bioinformatic studies had suggested that amino acid synthesis, rather than protein degradation, is responsible for the observed BCAA increase in osmotically stressed Arabidopsis. However, whereas treatment with the protease inhibitor MG132 decreased drought-induced BCAA accumulation, inhibition of BCAA biosynthesis with the acetolactate synthase inhibitors chlorsulfuron and imazapyr did not. Additionally, overexpression of BRANCHED-CHAIN AMINO ACID TRANSFERASE2 (BCAT2), which is upregulated in response to osmotic stress and functions in BCAA degradation, decreased drought-induced BCAA accumulation. Together, these results demonstrate that BCAA accumulation in osmotically stressed Arabidopsis is primarily the result of protein degradation. After relief of the osmotic stress, BCAA homeostasis is restored over time by amino acid degradation involving BCAT2. Thus, drought-induced BCAA accumulation is different from that of proline, which is accumulated due to de novo synthesis in an abscisic acid-independent manner and remains elevated for a more prolonged period of time after removal of

Comparison of anorectic potencies of the trichothecenes T-2 toxin, HT-2 toxin and satratoxin G to the ipecac alkaloid emetine

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Wenda Wu

2015-01-01

Full Text Available Trichothecene mycotoxins, potent translational inhibitors that are associated with human food poisonings and damp-building illnesses, are of considerable concern to animal and human health. Food refusal is a hallmark of exposure of experimental animals to deoxynivalenol (DON and other Type B trichothecenes but less is known about the anorectic effects of foodborne Type A trichothecenes (e.g., T-2 toxin, HT-2 toxin, airborne Type D trichothecenes (e.g., satratoxin G [SG] or functionally analogous metabolites that impair protein synthesis. Here, we utilized a well-described mouse model of food intake to compare the anorectic potencies of T-2 toxin, HT-2 toxin, and SG to that of emetine, a medicinal alkaloid derived from ipecac that inhibits translation. Intraperitoneal (IP administration with T-2 toxin, HT-2 toxin, emetine and SG evoked anorectic responses that occurred within 0.5 h that lasted up to 96, 96, 3 and 96 h, respectively, with lowest observed adverse effect levels (LOAELs being 0.1, 0.1, 2.5 and 0.25 mg/kg BW, respectively. When delivered via natural routes of exposure, T-2 toxin, HT-2 toxin, emetine (oral and SG (intranasal induced anorectic responses that lasted up to 48, 48, 3 and 6 h, respectively with LOAELs being 0.1, 0.1, 0.25, and 0.5 mg/kg BW, respectively. All four compounds were generally much more potent than DON which was previously observed to have LOAELs of 1 and 2.5 mg/kg BW after IP and oral dosing, respectively. Taken together, these anorectic potency data will be valuable in discerning the relative risks from trichothecenes and other translational inhibitors of natural origin.

c-Jun Proto-Oncoprotein Plays a Protective Role in Lung Epithelial Cells Exposed to Staphylococcal α-Toxin

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Alejandro J. Moyano

2018-05-01

Full Text Available c-Jun is a member of the early mammalian transcriptional regulators belonging to the AP-1 family, which participates in a wide range of cellular processes such as proliferation, apoptosis, tumorigenesis, and differentiation. Despite its established role in cell survival upon stress, its participation in the stress response induced by bacterial infections has been poorly investigated. To study the potential role of c-Jun in this context we choose the widely studied α-toxin produced by Staphylococcus aureus, a pore-forming toxin that is a critical virulence factor in the pathogenesis of these bacteria. We analyzed the effect of α-toxin treatment in the activation, expression, and protein levels of c-Jun in A549 lung epithelial cells. Furthermore, we explored the role of c-Jun in the cellular fate after exposure to α-toxin. Our results show that staphylococcal α-toxin per se is able to activate c-Jun by inducing phosphorylation of its Serine 73 residue. Silencing of the JNK (c-Jun N-terminal Kinase signaling pathway abrogated most of this activation. On the contrary, silencing of the ERK (Extracellular Signal-Regulated Kinase pathway exacerbated this response. Intriguingly, while the exposure to α-toxin induced a marked increase in the levels of c-Jun transcripts, c-Jun protein levels noticeably decreased in the same time-frame as a consequence of active proteolytic degradation through the proteasome-dependent pathway. In addition, we established that c-Jun promoted cell survival when cells were challenged with α-toxin. Similarly, c-Jun phosphorylation was also induced in cells upon intoxication with the cytolysin produced by Vibrio cholerae in a JNK-dependent manner, suggesting that c-Jun-JNK axis would be a conserved responsive cellular pathway to pore-forming toxins. This study contributes to understanding the role of the multifaceted c-Jun proto-oncoprotein in cell response to bacterial pore-forming toxins, positioning it as a relevant

Epidermal Growth Factor Receptor Signaling Enhances the Proinflammatory Effects of Staphylococcus aureus Gamma-Toxin on the Mucosa.

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Gillman, Aaron N; Breshears, Laura M; Kistler, Charles K; Finnegan, Patrick M; Torres, Victor J; Schlievert, Patrick M; Peterson, Marnie L

2017-06-28

Staphylococcus aureus ( S. aureus ) produces many different exotoxins including the gamma-toxins, HlgAB and HlgCB. Gamma-toxins form pores in both leukocyte and erythrocyte membranes, resulting in cell lysis. The genes encoding gamma-toxins are present in most strains of S. aureus, and are commonly expressed in clinical isolates recovered from menstrual Toxic Shock Syndrome (mTSS) patients. This study set out to investigate the cytotoxic and proinflammatory effects of gamma-toxins on vaginal epithelial surfaces. We found that both HlgAB and HlgCB were cytotoxic to cultured human vaginal epithelial cells (HVECs) and induced cytokine production at sub-cytotoxic doses. Cytokine production induced by gamma-toxin treatment of HVECs was found to involve epidermal growth factor receptor (EGFR) signaling and mediated by shedding of EGFR ligands from the cell surface. The gamma-toxin subunits displayed differential binding to HVECs (HlgA 93%, HlgB 97% and HlgC 28%) with both components (HlgAB or HlgCB) required for maximum detectable binding and significant stimulation of cytokine production. In studies using full thickness ex vivo porcine vaginal mucosa, HlgAB or HlgCB stimulated a dose-dependent cytokine response, which was reduced significantly by inhibition of EGFR signaling. The effects of gamma-toxins on porcine vaginal tissue and cultured HVECs were validated using ex vivo human ectocervical tissue. Collectively, these studies have identified the EGFR-signaling pathway as a key component in gamma-toxin-induced proinflammatory changes at epithelial surfaces and highlight a potential therapeutic target to diminish toxigenic effects of S. aureus infections.

Botulinum toxin-induced facial muscle paralysis affects amygdala responses to the perception of emotional expressions: preliminary findings from an A-B-A design

OpenAIRE

Kim, M Justin; Neta, Maital; Davis, F Caroline; Ruberry, Erika J; Dinescu, Diana; Heatherton, Todd F; Stotland, Mitchell A; Whalen, Paul J

2014-01-01

Background It has long been suggested that feedback signals from facial muscles influence emotional experience. The recent surge in use of botulinum toxin (BTX) to induce temporary muscle paralysis offers a unique opportunity to directly test this ?facial feedback hypothesis.? Previous research shows that the lack of facial muscle feedback due to BTX-induced paralysis influences subjective reports of emotional experience, as well as brain activity associated with the imitation of emotional fa...

Anorectic response to the trichothecene T-2 toxin correspond to plasma elevations of the satiety hormone glucose-dependent insulinotropic polypeptide and peptide YY3-36.

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Sheng, Kun; Zhang, Hua; Yue, Jianming; Gu, Wei; Gu, Chao; Zhang, Haibin; Wu, Wenda

2018-04-22

T-2 toxin, a potent type A trichothecene mycotoxin, is produced by various Fusarium species and can negatively impact animal and human health. Although anorexia induction is a common hallmark of T-2 toxin-induced toxicity, the underlying mechanisms for this adverse effect are not fully understood. The goal of this study was to determine the roles of two gut satiety hormones, glucose-dependent insulinotropic polypeptide (GIP) and Peptide YY 3-36 (PYY 3-36 ) in anorexia induction by T-2 toxin. Elevations of plasma GIP and PYY 3-36 markedly corresponded to anorexia induction following oral exposure to T-2 toxin using a nocturnal mouse anorexia model. Direct administration of exogenous GIP and PYY 3-36 similarly induced anorectic responses. Furthermore, the GIP receptor antagonist Pro3GIP dose-dependently attenuated both GIP- and T-2 toxin-induced anorectic responses. Pretreatment with NPY2 receptor antagonist JNJ-31020028 induced a dose-dependent attenuation of both PYY 3-36 - and T-2 toxin-induced anorectic responses. To summarize, these findings suggest that both GIP and PYY 3-36 might be critical mediators of anorexia induction by T-2 toxin. Copyright © 2018 Elsevier B.V. All rights reserved.

Induced Plant Accumulation of Lithium

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Laurence Kavanagh

2018-02-01

Full Text Available Lithium’s (Li value has grown exponentially since the development of Li-ion batteries. It is usually accessed in one of two ways: hard rock mineral mining or extraction from mineral-rich brines. Both methods are expensive and require a rich source of Li. This paper examines the potential of agro-mining as an environmentally friendly, economically viable process for extracting Li from low grade ore. Agro-mining exploits an ability found in few plant species, to accumulate substantial amounts of metals in the above ground parts of the plant. Phyto-mined metals are then retrieved from the incinerated plants. Although the actual amount of metal collected from a crop may be low, the process has been shown to be profitable. We have investigated the suitability of several plant species including: Brassica napus and Helianthus annuus, as Li-accumulators under controlled conditions. Large plant trials were carried out with/without chelating agents to encourage Li accumulation. The question we sought to answer was, can any of the plant species investigated accumulate Li at levels high enough to justify using them to agro-mine Li. Results show maximum accumulated levels of >4000 mg/kg Li in some species. Our data suggests that agro-mining of Li is a potentially viable process.

Proteomic analysis of the action of the Mycobacterium ulcerans toxin mycolactone: targeting host cells cytoskeleton and collagen.

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José B Gama

2014-08-01

Full Text Available Buruli ulcer (BU is a neglected tropical disease caused by Mycobacterium ulcerans. The tissue damage characteristic of BU lesions is known to be driven by the secretion of the potent lipidic exotoxin mycolactone. However, the molecular action of mycolactone on host cell biology mediating cytopathogenesis is not fully understood. Here we applied two-dimensional electrophoresis (2-DE to identify the mechanisms of mycolactone's cellular action in the L929 mouse fibroblast proteome. This revealed 20 changed spots corresponding to 18 proteins which were clustered mainly into cytoskeleton-related proteins (Dync1i2, Cfl1, Crmp2, Actg1, Stmn1 and collagen biosynthesis enzymes (Plod1, Plod3, P4ha1. In line with cytoskeleton conformational disarrangements that are observed by immunofluorescence, we found several regulators and constituents of both actin- and tubulin-cytoskeleton affected upon exposure to the toxin, providing a novel molecular basis for the effect of mycolactone. Consistent with these cytoskeleton-related alterations, accumulation of autophagosomes as well as an increased protein ubiquitination were observed in mycolactone-treated cells. In vivo analyses in a BU mouse model revealed mycolactone-dependent structural changes in collagen upon infection with M. ulcerans, associated with the reduction of dermal collagen content, which is in line with our proteomic finding of mycolactone-induced down-regulation of several collagen biosynthesis enzymes. Our results unveil the mechanisms of mycolactone-induced molecular cytopathogenesis on exposed host cells, with the toxin compromising cell structure and homeostasis by inducing cytoskeleton alterations, as well as disrupting tissue structure, by impairing the extracellular matrix biosynthesis.

Proteomic analysis of the action of the Mycobacterium ulcerans toxin mycolactone: targeting host cells cytoskeleton and collagen.

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Gama, José B; Ohlmeier, Steffen; Martins, Teresa G; Fraga, Alexandra G; Sampaio-Marques, Belém; Carvalho, Maria A; Proença, Fernanda; Silva, Manuel T; Pedrosa, Jorge; Ludovico, Paula

2014-08-01

Buruli ulcer (BU) is a neglected tropical disease caused by Mycobacterium ulcerans. The tissue damage characteristic of BU lesions is known to be driven by the secretion of the potent lipidic exotoxin mycolactone. However, the molecular action of mycolactone on host cell biology mediating cytopathogenesis is not fully understood. Here we applied two-dimensional electrophoresis (2-DE) to identify the mechanisms of mycolactone's cellular action in the L929 mouse fibroblast proteome. This revealed 20 changed spots corresponding to 18 proteins which were clustered mainly into cytoskeleton-related proteins (Dync1i2, Cfl1, Crmp2, Actg1, Stmn1) and collagen biosynthesis enzymes (Plod1, Plod3, P4ha1). In line with cytoskeleton conformational disarrangements that are observed by immunofluorescence, we found several regulators and constituents of both actin- and tubulin-cytoskeleton affected upon exposure to the toxin, providing a novel molecular basis for the effect of mycolactone. Consistent with these cytoskeleton-related alterations, accumulation of autophagosomes as well as an increased protein ubiquitination were observed in mycolactone-treated cells. In vivo analyses in a BU mouse model revealed mycolactone-dependent structural changes in collagen upon infection with M. ulcerans, associated with the reduction of dermal collagen content, which is in line with our proteomic finding of mycolactone-induced down-regulation of several collagen biosynthesis enzymes. Our results unveil the mechanisms of mycolactone-induced molecular cytopathogenesis on exposed host cells, with the toxin compromising cell structure and homeostasis by inducing cytoskeleton alterations, as well as disrupting tissue structure, by impairing the extracellular matrix biosynthesis.

The rGel/BLyS Fusion Toxin Inhibits Diffuse Large B-cell Lymphoma Growth In Vitro and In Vivo

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Mi-Ae Lyu

2010-05-01

Full Text Available Diffuse large B-cell lymphoma (DLBCL is an aggressive subtype of B-cell non-Hodgkin lymphoma (NHL and accounts for 30%to 40%of NHL. Molecules targeting nuclear factor-κB (NF-κB are expected to be of therapeutic value in those tumors where NF-κB seems to play a unique survival role such as activated B-cell (ABC-subtype DLBCL. We previously generated a rGel/BLyS fusion toxin for receptor-mediated delivery of the rGel toxin specifically to malignant B cells. In this study, we examined this fusion toxin for its ability to suppress DLBCL growth in vitro and in vivo. rGel/BLyS was specifically cytotoxic to DLBCL lines expressing all three BLyS receptors and constitutively active NF-κB. Treatment with rGel/BLyS induced down-regulation of the phosphorylation of inhibitory subunit of NF-κB (IκB-α, inhibition of NF-κB DNA-binding activity, and accumulation of IκB-α. In agreement with these results, we additionally found that rGel/BLyS downregulated levels of several NF-κB targets including Bcl-xL, Mcl-1, survivin, and x-chromosome linked inhibitor-of-apoptosis. Treatment also induced up-regulation of Bax and apoptosis through caspase-3 activation and poly ADP-ribose polymerase cleavage. Importantly, rGel/BLyS significantly inhibited tumor growth (P < .05 in a DLBCL xenograft model. Thus, our results indicate that rGel/BLyS is an excellent candidate for the treatment of aggressive NHLs that are both dependent on NF-κB and are resistant to conventional chemotherapeutic regimens.

Clostridium difficile chimeric toxin receptor binding domain vaccine induced protection against different strains in active and passive challenge models.

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Tian, Jing-Hui; Glenn, Gregory; Flyer, David; Zhou, Bin; Liu, Ye; Sullivan, Eddie; Wu, Hua; Cummings, James F; Elllingsworth, Larry; Smith, Gale

2017-07-24

Clostridium difficile is the number one cause of nosocomial antibiotic-associated diarrhea in developed countries. Historically, pathogenesis was attributed two homologous glucosylating toxins, toxin-A (TcdA) and toxin-B (TcdB). Over the past decade, however, highly virulent epidemic strains of C. difficile (B1/NAP1/027) have emerged and are linked to an increase in morbidity and mortality. Increased virulence is attributed to multiple factors including: increased production of A- and B-toxins; production of binary toxin (CDT); and the emergence of more toxic TcdB variants (TcdB (027) ). TcdB (027) is more cytotoxicity to cells; causes greater tissue damage and toxicity in animals; and is antigenically distinct from historical TcdB (TcdB (003) ). Broadly protective vaccines and therapeutic antibody strategies, therefore, may target TcdA, TcdB variants and CDT. To facilitate the generation of multivalent toxin-based C. difficile vaccines and therapeutic antibodies, we have generated fusion proteins constructed from the receptor binding domains (RBD) of TcdA, TcdB (003) , TcdB (027) and CDT. Herein, we describe the development of a trivalent toxin (T-toxin) vaccine (CDTb/TcdB (003) /TcdA) and quadravalent toxin (Q-toxin) vaccine (CDTb/TcB (003) /TcdA/TcdB (027) ) fusion proteins that retain the protective toxin neutralizing epitopes. Active immunization of mice or hamsters with T-toxin or Q-toxin fusion protein vaccines elicited the generation of toxin neutralizing antibodies to each of the toxins. Hamsters immunized with the Q-toxin vaccine were broadly protected against spore challenge with historical C. difficile 630 (toxinotype 0/ribotype 003) and epidemic NAP1 (toxinotype III/ribotype 027) strains. Fully human polyclonal antitoxin IgG was produced by immunization of transgenic bovine with these fusion proteins. In passive transfer studies, mice were protected against lethal toxin challenge. Hamsters treated with human antitoxin IgG were completely protected when

Converting a Staphylococcus aureus toxin into effective cyclic pseudopeptide antibiotics.

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Solecki, Olivia; Mosbah, Amor; Baudy Floc'h, Michèle; Felden, Brice

2015-03-19

Staphylococcus aureus produces peptide toxins that it uses to respond to environmental cues. We previously characterized PepA1, a peptide toxin from S. aureus, that induces lytic cell death of both bacterial and host cells. That led us to suggest that PepA1 has an antibacterial activity. Here, we demonstrate that exogenously provided PepA1 has activity against both Gram-positive and Gram-negative bacteria. We also see that PepA1 is significantly hemolytic, thus limiting its use as an antibacterial agent. To overcome these limitations, we converted PepA1 into nonhemolytic derivatives. Our most promising derivative is a cyclic heptapseudopeptide with inconsequential toxicity to human cells, enhanced stability in human sera, and sharp antibacterial activity. Mechanistically, linear and helical PepA1 derivatives form pores at the bacterial and erythrocyte surfaces, while the cyclic peptide induces bacterial envelope reorganization, with insignificant action on the erythrocytes. Our work demonstrates that bacterial toxins might be an attractive starting point for antibacterial drug development. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antiradiation Antitoxin IgG : Immunological neutralization of Radiation Toxins at Acute Radiation Syndromes.

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Popov, Dmitri; Maliev, Slava

Introduction: High doses of radiation induce apoptotic necrosis of radio-sensitive cells. Mild doses of radiation induce apoptosis or controlled programmed death of radio-sensitive cells with-out development of inflammation and formation of Radiation Toxins. Cell apoptotic necrosis initiates Radiation Toxins (RT)formation. Radiation Toxins play an important role as a trig-ger mechanism for inflammation development and cell lysis. If an immunotherapy approach to treatment of the acute radiation syndromes (ARS) were to be developed, a consideration could be given to neutralization of radiation toxins (Specific Radiation Determinants-SRD) by specific antiradiation antibodies. Therapeutic neutralization effects of the blocking anti-radiation antibodies on the circulated RT had been studied. Radiation Toxins were isolated from the central lymph of irradiated animals with Cerebrovascular(Cv ARS),Cardiovascular (Cr ARS),Gastrointestinal(Gi ARS) and Haemopoietic (Hp ARS) forms of ARS. To accomplish this objective, irradiated animals were injected with a preparation of anti-radiation immunoglobulin G (IgG) obtained from hyperimmune donors. Radiation-induced toxins that we call Specific Radiation Determinants (SRD) possess toxic (neurotoxic, haemotoxic) characteristics as well as specific antigenic properties. Depending on direct physiochemical radiation damage, they can induce development of many of the pathological processes associated with ARS. We have tested several specific hyperimmune IgG preparations against these radiation toxins and ob-served that their toxic properties were neutralized by the specific antiradiation IgGs. Material and Methods: A scheme of experiments was following: 1.Isolation of radiation toxins (RT) from the central lymph of irradiated animals with different form of ARS. 2.Transformation of a toxic form of the RT to a toxoid form of the RT. 3.Immunization of radiation naive animals. Four groups of rabbits were inoculated with a toxoid form of SRD

Regulating Toxin-Antitoxin Expression: Controlled Detonation of Intracellular Molecular Timebombs

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Finbarr Hayes

2014-01-01

Full Text Available Genes for toxin-antitoxin (TA complexes are widely disseminated in bacteria, including in pathogenic and antibiotic resistant species. The toxins are liberated from association with the cognate antitoxins by certain physiological triggers to impair vital cellular functions. TAs also are implicated in antibiotic persistence, biofilm formation, and bacteriophage resistance. Among the ever increasing number of TA modules that have been identified, the most numerous are complexes in which both toxin and antitoxin are proteins. Transcriptional autoregulation of the operons encoding these complexes is key to ensuring balanced TA production and to prevent inadvertent toxin release. Control typically is exerted by binding of the antitoxin to regulatory sequences upstream of the operons. The toxin protein commonly works as a transcriptional corepressor that remodels and stabilizes the antitoxin. However, there are notable exceptions to this paradigm. Moreover, it is becoming clear that TA complexes often form one strand in an interconnected web of stress responses suggesting that their transcriptional regulation may prove to be more intricate than currently understood. Furthermore, interference with TA gene transcriptional autoregulation holds considerable promise as a novel antibacterial strategy: artificial release of the toxin factor using designer drugs is a potential approach to induce bacterial suicide from within.

Structure, Biology, and Therapeutic Application of Toxin-Antitoxin Systems in Pathogenic Bacteria.

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Lee, Ki-Young; Lee, Bong-Jin

2016-10-22

Bacterial toxin-antitoxin (TA) systems have received increasing attention for their diverse identities, structures, and functional implications in cell cycle arrest and survival against environmental stresses such as nutrient deficiency, antibiotic treatments, and immune system attacks. In this review, we describe the biological functions and the auto-regulatory mechanisms of six different types of TA systems, among which the type II TA system has been most extensively studied. The functions of type II toxins include mRNA/tRNA cleavage, gyrase/ribosome poison, and protein phosphorylation, which can be neutralized by their cognate antitoxins. We mainly explore the similar but divergent structures of type II TA proteins from 12 important pathogenic bacteria, including various aspects of protein-protein interactions. Accumulating knowledge about the structure-function correlation of TA systems from pathogenic bacteria has facilitated a novel strategy to develop antibiotic drugs that target specific pathogens. These molecules could increase the intrinsic activity of the toxin by artificially interfering with the intermolecular network of the TA systems.

Electrophysiological response of chicken's jejunal epithelium to increasing levels of T-2 toxin.

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Yunus, Agha Waqar; Kröger, Susan; Tichy, Alexander; Zentek, Jürgen; Böhm, Josef

2013-02-01

The present investigations were conducted to test the effects of T-2 toxin on electrophysiological variables of jejunal epithelium of chicken. Jejunal segments of broilers were monitored in Ussing chambers in the presence of T-2 toxin at the levels of 0 (negative control), 0 (methanol/vehicle control), 0.1, 1, 5, and 10 μg/ml of buffer. T-2 toxin did not affect basal values of short circuit current (I(sc)), transmural potential difference, or tissue conductivity in the jejunal epithelium. T-2 toxin also did not statistically affect glucose-induced electrophysiological variables during the first 3 min of glucose induction. Compared to the vehicle control, the ouabain-sensitive I(sc) was negatively affected (P = 0.008) only under 5 μg of T-2 toxin/ml. Increasing levels of T-2 toxin negatively affected the ouabain-sensitive I(sc) in a cubic (P = 0.007) fashion. These data indicate that acute exposure to moderate levels of T-2 toxin may progressively impair the cation gradient across the jejunal epithelium.

Conceptual models of microseismicity induced by fluid injection

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Baro Urbea, J.; Lord-May, C.; Eaton, D. W. S.; Joern, D.

2017-12-01

Variations in the pore pressure due to fluid invasion are accountable for microseismic activity recorded in geothermal systems and during hydraulic fracturing operations. To capture this phenomenon on a conceptual level, invasion percolation models have been suggested to represent the flow network of fluids within a porous media and seismic activity is typically considered to be directly related to the expansion of the percolated area. Although such models reproduce scale-free frequency-magnitude distributions, the associated b-values of the Gutenberg-Richter relation do not align with observed data. Here, we propose an alternative conceptual invasion percolation model that decouples the fluid propagation from the microseismic events. Instead of a uniform pressure, the pressure is modeled to decay along the distance from the injection site. Wet fracture events are simulated with a stochastic spring block model exhibiting stick-slip dynamics as a result of the variations of the pore pressure. We show that the statistics of the stick-slip events are scale-free, but now the b-values depend on the level of heterogeneity in the local static friction coefficients. Thus, this model is able to reproduce the wide spectrum of b-values observed in field catalogs associated with fluid induced microseismicity. Moreover, the spatial distribution of microseismic events is also consistent with observations.

Induced fluid rotation and bistable fluidic turn-down valves (a survey

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Tesař Václav

2015-01-01

Full Text Available Paper surveys engineering applications of an unusual fluidic principle — momentum transfer through a relatively small communicating window into a vortex chamber, where the initially stationary fluid is put into rotation. The transfer is often by shear stress acting in the window plane, but may be enhanced and perhaps even dominated by fluid flow crossing the boundary. The case of zero-time-mean fluid transport through the window has found use in experimental fluid mechanics: non-invasive measurement of wall shear stress on objects by evaluating the induced rotation in the vortex chamber. The case with the non-zero flow through the interface became the starting point in development of fluidic valves combining two otherwise mutually incompatible properties: bistability and flow turning down.

Evaluation of Rapid, Early Warning Approaches to Track Shellfish Toxins Associated with Dinophysis and Alexandrium Blooms

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Theresa K. Hattenrath-Lehmann

2018-01-01

Full Text Available Marine biotoxin-contaminated seafood has caused thousands of poisonings worldwide this century. Given these threats, there is an increasing need for improved technologies that can be easily integrated into coastal monitoring programs. This study evaluates approaches for monitoring toxins associated with recurrent toxin-producing Alexandrium and Dinophysis blooms on Long Island, NY, USA, which cause paralytic and diarrhetic shellfish poisoning (PSP and DSP, respectively. Within contrasting locations, the dynamics of pelagic Alexandrium and Dinophysis cell densities, toxins in plankton, and toxins in deployed blue mussels (Mytilus edulis were compared with passive solid-phase adsorption toxin tracking (SPATT samplers filled with two types of resin, HP20 and XAD-2. Multiple species of wild shellfish were also collected during Dinophysis blooms and used to compare toxin content using two different extraction techniques (single dispersive and double exhaustive and two different toxin analysis assays (liquid chromatography/mass spectrometry and the protein phosphatase inhibition assay (PP2A for the measurement of DSP toxins. DSP toxins measured in the HP20 resin were significantly correlated (R2 = 0.7–0.9, p < 0.001 with total DSP toxins in shellfish, but were detected more than three weeks prior to detection in deployed mussels. Both resins adsorbed measurable levels of PSP toxins, but neither quantitatively tracked Alexandrium cell densities, toxicity in plankton or toxins in shellfish. DSP extraction and toxin analysis methods did not differ significantly (p > 0.05, were highly correlated (R2 = 0.98–0.99; p < 0.001 and provided complete recovery of DSP toxins from standard reference materials. Blue mussels (Mytilus edulis and ribbed mussels (Geukensia demissa were found to accumulate DSP toxins above federal and international standards (160 ng g−1 during Dinophysis blooms while Eastern oysters (Crassostrea virginica and soft shell clams (Mya

Monitoring of Dinophysis species and diarrhetic shellfish toxins in Flødevigen Bay, Norway: inter-annual variability over a 25-year time-series.

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Naustvoll, L-J; Gustad, E; Dahl, E

2012-01-01

The accumulation of phycotoxins in bivalve mussels associated with mussels feeding on toxic phytoplankton is a well-known phenomenon in Norway. Regular monitoring for 25 years has revealed that accumulation of Diarrhetic Shellfish poisoning (DSP) toxins in mussels is the main phycotoxin problem along the Norwegian coast. The aim of this study was to evaluate possible trends over time of Dinophysis spp. and DSP as well as possible correlation between abundance of Dinophysis spp. and toxin accumulation in mussels, as based on intensive and regular monitoring at the southern coast of Norway at Flødevigen Bay. The main source organism causing a risk of DSP in Norway is Dinophysis acuta. However, it cannot be excluded that other Dinophysis spp., e.g. D. acuminata and D. norvegica, may contribute to the total accumulation of toxins. The variability in the occurrence of these species is high at both short- and long-term; between days and between years. There are, however, some important overall patterns in the occurrence of the species during the last decades. Dinophysis acuminata and D. norvegica have mainly been abundant from March to December, whereas D. acuta has typically occurred in late summer and autumn (August-December). For all three species we have observed a narrowing of the peak season since 2002 at the same time as they have become less abundant. Coincident with these changes, the problem of the accumulation of DSP toxins in mussels along the southern coast of Norway has declined significantly, but it is still mainly restricted to the autumn. Why the cell concentration of Dinophysis spp. has declined after 2002 is not obvious, but this has occurred in a period with relatively high summer temperatures. The relatively simultaneous changes in physical, chemical and biological factors of the pelagic ecosystem along the southern coast of Norway indicate that complicated ecological interactions may be involved.

Molecular evolution and diversification of snake toxin genes, revealed by analysis of intron sequences.

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Fujimi, T J; Nakajyo, T; Nishimura, E; Ogura, E; Tsuchiya, T; Tamiya, T

2003-08-14

The genes encoding erabutoxin (short chain neurotoxin) isoforms (Ea, Eb, and Ec), LsIII (long chain neurotoxin) and a novel long chain neurotoxin pseudogene were cloned from a Laticauda semifasciata genomic library. Short and long chain neurotoxin genes were also cloned from the genome of Laticauda laticaudata, a closely related species of L. semifasciata, by PCR. A putative matrix attached region (MAR) sequence was found in the intron I of the LsIII gene. Comparative analysis of 11 structurally relevant snake toxin genes (three-finger-structure toxins) revealed the molecular evolution of these toxins. Three-finger-structure toxin genes diverged from a common ancestor through two types of evolutionary pathways (long and short types), early in the course of evolution. At a later stage of evolution in each gene, the accumulation of mutations in the exons, especially exon II, by accelerated evolution may have caused the increased diversification in their functions. It was also revealed that the putative MAR sequence found in the LsIII gene was integrated into the gene after the species-level divergence.

Air bubbles induce a critical continuous stress to prevent marine biofouling accumulation

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Belden, Jesse; Menesses, Mark; Dickenson, Natasha; Bird, James

2017-11-01

Significant shear stresses are needed to remove established hard fouling organisms from a ship hull. Given that there is a link between the amount of time that fouling accumulates and the stress required to remove it, it is not surprising that more frequent grooming requires less shear stress. One approach to mitigate marine biofouling is to continuously introduce a curtain of air bubbles under a submerged surface; it is believed that this aeration exploits the small stresses induced by rising bubbles to continuously prevent accumulation. Although curtains of rising bubbles have successfully prevented biofouling accumulation, it is unclear if a single stream of bubbles could maintain a clean surface. In this talk, we show that single bubble stream aeration can prevent biofouling accumulation in regions for which the average wall stress exceeds approximately 0.01 Pa. This value is arrived at by comparing observations of biofouling growth and prevention from field studies with laboratory measurements that probe the associated flow fields. We also relate the spatial and temporal characteristics of the flow to the size and frequency of the rising bubbles, which informs the basic operating conditions required for aeration to continuously prevent biofouling accumulation.

Feasibility of a Day-Camp Model of Modified Constraint-Induced Movement Therapy with and without Botulinum Toxin A Injection for Children with Hemiplegia

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Eliasson, Ann-Christin; Shaw, Karin; Ponten, Eva; Boyd, Roslyn; Krumlinde-Sundholm, Lena

2009-01-01

The objective of the study was to investigate the feasibility of modified constraint-induced (CI) therapy provided in a 2-week day-camp model with and without intramuscular botulinum toxin type A (BoNT-A) injections for children with congenital cerebral palsy. Sixteen children with congenital hemiplegia, Manual Ability Classification System (MACS)…

Effect of pertussis and cholera toxins administered supraspinally on CA3 hippocampal neuronal cell death and the blood glucose level induced by kainic acid in mice.

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Kim, Chea-Ha; Park, Soo-Hyun; Sim, Yun-Beom; Sharma, Naveen; Kim, Sung-Su; Lim, Su-Min; Jung, Jun-Sub; Suh, Hong-Won

2014-12-01

The effect of cholera toxin (CTX) or pertussis toxin (PTX) administered supraspinally on hippocampal neuronal cell death in CA3 region induced by kainic acid (KA) was examined in mice. After the pretreatment with either PTX or CTX intracerebroventricularly (i.c.v.), mice were administered i.c.v. with KA. The i.c.v. treatment with KA caused a neuronal cell death in CA3 region and PTX, but not CTX, attenuated the KA-induced neuronal cell death. In addition, i.c.v. treatment with KA caused an elevation of the blood glucose level. The i.c.v. PTX pretreatment alone caused a hypoglycemia and inhibited KA-induced hyperglycemic effect. However, i.c.v. pretreatment with CTX did not affect the basal blood glucose level and KA-induced hyperglycemic effect. Moreover, KA administered i.c.v. caused an elevation of corticosterone level and reduction of the blood insulin level. Whereas, i.c.v. pretreatment with PTX further enhanced KA-induced up-regulation of corticosterone level. Furthermore, i.c.v. administration of PTX alone increased the insulin level and KA-induced hypoinsulinemic effect was reversed. In addition, PTX pretreatment reduces the KA-induced seizure activity. Our results suggest that supraspinally administered PTX, exerts neuroprotective effect against KA-induced neuronal cells death in CA3 region and neuroprotective effect of PTX is mediated by the reduction of KA-induced blood glucose level. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Adenylate cyclase toxin promotes internalisation of integrins and raft components and decreases macrophage adhesion capacity.

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César Martín

Full Text Available Bordetella pertussis, the bacterium that causes whooping cough, secretes an adenylate cyclase toxin (ACT that must be post-translationally palmitoylated in the bacterium cytosol to be active. The toxin targets phagocytes expressing the CD11b/CD18 integrin receptor. It delivers a catalytic adenylate cyclase domain into the target cell cytosol producing a rapid increase of intracellular cAMP concentration that suppresses bactericidal functions of the phagocyte. ACT also induces calcium fluxes into target cells. Biochemical, biophysical and cell biology approaches have been applied here to show evidence that ACT and integrin molecules, along with other raft components, are rapidly internalized by the macrophages in a toxin-induced calcium rise-dependent process. The toxin-triggered internalisation events occur through two different routes of entry, chlorpromazine-sensitive receptor-mediated endocytosis and clathrin-independent internalisation, maybe acting in parallel. ACT locates into raft-like domains, and is internalised, also in cells devoid of receptor. Altogether our results suggest that adenylate cyclase toxin, and maybe other homologous pathogenic toxins from the RTX (Repeats in Toxin family to which ACT belongs, may be endowed with an intrinsic capacity to, directly and efficiently, insert into raft-like domains, promoting there its multiple activities. One direct consequence of the integrin removal from the cell surface of the macrophages is the hampering of their adhesion ability, a fundamental property in the immune response of the leukocytes that could be instrumental in the pathogenesis of Bordetella pertussis.

Adenylate cyclase toxin promotes internalisation of integrins and raft components and decreases macrophage adhesion capacity.

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Martín, César; Uribe, Kepa B; Gómez-Bilbao, Geraxane; Ostolaza, Helena

2011-02-23

Bordetella pertussis, the bacterium that causes whooping cough, secretes an adenylate cyclase toxin (ACT) that must be post-translationally palmitoylated in the bacterium cytosol to be active. The toxin targets phagocytes expressing the CD11b/CD18 integrin receptor. It delivers a catalytic adenylate cyclase domain into the target cell cytosol producing a rapid increase of intracellular cAMP concentration that suppresses bactericidal functions of the phagocyte. ACT also induces calcium fluxes into target cells. Biochemical, biophysical and cell biology approaches have been applied here to show evidence that ACT and integrin molecules, along with other raft components, are rapidly internalized by the macrophages in a toxin-induced calcium rise-dependent process. The toxin-triggered internalisation events occur through two different routes of entry, chlorpromazine-sensitive receptor-mediated endocytosis and clathrin-independent internalisation, maybe acting in parallel. ACT locates into raft-like domains, and is internalised, also in cells devoid of receptor. Altogether our results suggest that adenylate cyclase toxin, and maybe other homologous pathogenic toxins from the RTX (Repeats in Toxin) family to which ACT belongs, may be endowed with an intrinsic capacity to, directly and efficiently, insert into raft-like domains, promoting there its multiple activities. One direct consequence of the integrin removal from the cell surface of the macrophages is the hampering of their adhesion ability, a fundamental property in the immune response of the leukocytes that could be instrumental in the pathogenesis of Bordetella pertussis.

Applications of disorder-induced melting concept to critical-solute-accumulation processes

International Nuclear Information System (INIS)

Lam, N.Q.; Okamoto, P.R.; Heuer, J.K.

2001-01-01

A generalized version of the Lindemann melting criterion has recently been used to develop a unified thermodynamic description of disorder-induced amorphization and heat-induced melting. This concept of amorphization as a melting process is based on the fact that the melting temperature of a defective crystal driven far from equilibrium will decrease relative to that of its defect-free equilibrium state. The broader view of melting provides a new perspective of damage-accumulation processes such as radiation damage, ion implantation, ion beam mixing, plastic deformation, and fracture. For example, within this conceptual framework, disorder-induced amorphization is simply polymorphous melting of a critically disordered crystal at temperatures below the glass transition temperature. In the present communication, we discuss the application of the concept to two specific cases: amorphous phase formation during ion implantation and solute segregation-induced intergranular fracture

Pre-cancerous changes in urothelial endocytic vesicle leakage, fatty acid composition, and As and associated element concentrations after arsenic exposure

International Nuclear Information System (INIS)

Grasso, E.J.; Bongiovanni, G.A.; Perez, R.D.; Calderon, R.O.

2011-01-01

The urothelium covering the luminal surface of the urinary bladder has developed an efficient permeability barrier that protects it against the back-flow of toxins eliminated in the urine. The subapical endocytic vesicles containing the urinary bladder fluid phase are formed during the micturition cycle by endocytosis processes of the superficial cells. In normal conditions, the permeability barrier of the endocytic vesicles blocks the passage of the fluid phase to the cellular cytoplasm and the fluid is recycled to the bladder lumen. The aim of this work was to investigate the alteration of the endocytic vesicle membrane permeability barrier to toxins such as iAs (inorganic arsenic) administered in drinking water. By using an induced endocytosis model and the fluorescence requenching technique, it is shown that the exposure of rats to ingestion of water containing iAs not only induced pre-cancerous morphological changes, but allowed the differential leakage of an endocytosed fluorescent marker, HPTS, and its quencher, DPX, (hydroxypyrene-1,3,6-trisulfonic acid and p-xylene-bis-pyridinium bromide, respectively) out of the vesicular lumen. The leakage of the cationic DPX was almost complete, while the release of the anionic HPTS molecule was partial and higher in arsenic-treated-rats than in controls. Such membrane alteration would allow the toxins to elude the permeability barrier and to leak out of the endocytic vesicles, thus establishing a 'bypass' to the permeability barrier. The retention of As in the urinary bladder, assessed by synchrotron radiation X-ray fluorescence spectrometry (SR-μXRF), was lower than the kidney accumulation of arsenic previously observed by our group and was accompanied by altered concentrations of K, Ca, Fe, Cu and Zn, all ions related to cellular metabolism. The results support the hypothesis that low amounts of endocytosed As can accumulate in the interior of the urothelial superficial cells and initiate the cytotoxic effects

Effects of cholera toxin on human colon carcinoma cell lines.

Science.gov (United States)

Barkla, D H; Whitehead, R H; Hayward, I P

1992-10-01

This study reports on changes in morphology and membrane transport in 5 human colon carcinoma cell lines treated with cholera toxin (CT). Three of the cell lines that grew as monolayers (LIM 1215, LIM 1899, LIM 2099) and 1 that grew as floating clumps (LIM 2408) did not show morphological changes after CT treatment. However, cell line LIM 1863 that grows as floating "crypt-like" organoids showed rapid and distinctive changes in morphology and membrane transport after CT treatment. At 1 and 6 hrs after CT treatment, light and transmission electron microscopy revealed rapid dilatation of the central lumen of organoids and the appearance of 2 populations of apical vesicular inclusions. The first population was unusual in being non-membrane bound and limited by fuzzy filamentous material. The second population was membrane bound. Scanning electron microscopy at 1-6 hr after CT treatment showed swelling and loss of surface microvilli on some, but not all, cells. At 24 hr after CT treatment the majority of organoids showed evidence of fluid accumulation and small apical vesicles coalesced to form large single vacuoles that obliterated normal cell morphology. By 48 hr, continued swelling produced extreme attenuation of the plasma membrane with cells taking on an "endothelial cell-like" appearance. The response to CT was dose-dependent. Uptake studies using 86Rubidium and blocking studies using ouabain and amiloride indicated that CT is acting on the Na+/K+ ATPase membrane pump to cause the increased fluid uptake by LIM 1863 cells. This study is the first to report specific morphological changes in intestine-derived cells in response to CT.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation of Clostridium difficile and Detection of A and B Toxins Encoding Genes

Directory of Open Access Journals (Sweden)

Abbas Ali Imani Fooladi

2014-02-01

Full Text Available Background: Clostridium difficile is the most important anaerobic, gram positive, spore forming bacillus which is known as a prevalent factor leading to antibiotic associated diarrheas and is the causative agent of pseudomembrane colitis. The role of this bacterium along with the over use of antibiotics have been proved to result in colitis. The major virulence factors of these bacteria are the A and B toxins. Objectives: The purpose of this study was to isolate C. difficile from stool samples and detect A and B toxins encoding genes, in order toserve as a routine method for clinical diagnosis. Materials and Methods: Recognition of A and B toxins encoding genes by uniplex and multiplex PCR using two pairs of primers from 136 accumulated stool samples. Results: Results of the present study showed that out of 136 stool samples, three C. difficile were isolated and these strains contained A and B toxins encoding genes. Conclusions: It was concluded that although detection of C. difficile from stool samples based on PCR (polymerase chain reaction is expensive, yet this method is more sensitive and less time-consuming than culture methods and can be used as a clinical laboratory test.

Efficacy of botulinum toxins on bruxism: an evidence-based review.

Science.gov (United States)

Long, Hu; Liao, Zhengyu; Wang, Yan; Liao, Lina; Lai, Wenli

2012-02-01

The objective of this study was to assess the efficacy of botulinum toxins on bruxism. Electronic databases (PubMed, Embase and Science Citation Index), websites (Cochrane Central Register of Controlled Trials and ClinicalTrials.gov) and the literature database of SIGLE (System for Information on Grey Literature in Europe) were searched from January 1990 to April 2011 for randomised controlled trials or nonrandomised studies assessing the efficacy of botulinum toxins on bruxism. There was no language restriction. Through a predefined search strategy, we retrieved 28 studies from PubMed, 94 from Embase, 60 from the Science Citation Index, two ongoing clinical trials and two from the Cochrane Central Register of Controlled Trials. Of these, only four studies met our inclusion criteria and were finally included. Of the four included studies, two were randomised controlled trials and two were controlled before-and-after studies. These studies showed that botulinum toxin injections can reduce the frequency of bruxism events, decrease bruxism-induced pain levels and satisfy patients' self-assessment with regard to the effectiveness of botulinum toxins on bruxism. In comparison with oral splint, botulinum toxins are equally effective on bruxism. Furthermore, botulinum toxin injections at a dosage of bruxism and are safe to use. Therefore, they can be used clinically for otherwise healthy patients with bruxism. © 2012 FDI World Dental Federation.

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

KAUST Repository

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

2015-01-01

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

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

KAUST Repository

Joffré, Enrique

2015-01-15

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

Multiple Pseudomonas species secrete exolysin-like toxins and provoke Caspase-1-dependent macrophage death.

Science.gov (United States)

Basso, Pauline; Wallet, Pierre; Elsen, Sylvie; Soleilhac, Emmanuelle; Henry, Thomas; Faudry, Eric; Attrée, Ina

2017-10-01

Pathogenic bacteria secrete protein toxins that provoke apoptosis or necrosis of eukaryotic cells. Here, we developed a live-imaging method, based on incorporation of a DNA-intercalating dye into membrane-damaged host cells, to study the kinetics of primary bone marrow-derived macrophages (BMDMs) mortality induced by opportunistic pathogen Pseudomonas aeruginosa expressing either Type III Secretion System (T3SS) toxins or the pore-forming toxin, Exolysin (ExlA). We found that ExlA promotes the activation of Caspase-1 and maturation of interleukin-1β. BMDMs deficient for Caspase-1 and Caspase-11 were resistant to ExlA-induced death. Furthermore, by using KO BMDMs, we determined that the upstream NLRP3/ASC complex leads to the Caspase-1 activation. We also demonstrated that Pseudomonas putida and Pseudomonas protegens and the Drosophila pathogen Pseudomonas entomophila, which naturally express ExlA-like toxins, are cytotoxic toward macrophages and provoke the same type of pro-inflammatory death as does ExlA + P. aeruginosa. These results demonstrate that ExlA-like toxins of two-partner secretion systems from diverse Pseudomonas species activate the NLRP3 inflammasome and provoke inflammatory pyroptotic death of macrophages. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Dietary toxins, endoplasmic reticulum (ER) stress and diabetes.

Science.gov (United States)

Hettiarachchi, Kalindi D; Zimmet, Paul Z; Myers, Mark A

2008-05-01

The incidence of Type 1 diabetes has been increasing at a rate too rapid to be due to changes in genetic risk. Instead changes in environmental factors are the likely culprit. The endoplasmic reticulum (ER) plays an important role in the production of newly synthesized proteins and interference with these processes leads to ER stress. The insulin-producing beta cells are particularly prone to ER stress as a result of their heavy engagement in insulin production. Increasing evidence suggests ER stress is central to initiation and progression of Type 1 diabetes. An early environmental exposure, such as toxins and viral infections, can impart a significant physiological load on beta cells to initiate abnormal processing of proinsulin, ER stress and insulin secretory defects. Release of altered proinsulin from the beta cells early in life may trigger autoimmunity in those with genetic susceptibility leading to cytokine-induced nitric oxide production and so exacerbating ER stress in beta cells, ultimately leading to apoptosis of beta cells and diabetes. Here we suggest that ER stress is an inherent cause of beta cell dysfunction and environmental factors, in particular dietary toxins derived from Streptomyces in infected root vegetables, can impart additional stress that aggravates beta cell death and progression to diabetes. Furthermore, we propose that the increasing incidence of Type 1 diabetes may be accounted for by increased dietary exposure to ER-stress-inducing Streptomyces toxins.

Development of an ELISA microarray assay for the sensitive and simultaneous detection of ten biodefense toxins.

Energy Technology Data Exchange (ETDEWEB)

Jenko, Kathryn; Zhang, Yanfeng; Kostenko, Yulia; Fan, Yongfeng; Garcia-Rodriguez, Consuelo; Lou, Jianlong; Marks, James D.; Varnum, Susan M.

2014-10-21

Plant and microbial toxins are considered bioterrorism threat agents because of their extreme toxicity and/or ease of availability. Additionally, some of these toxins are increasingly responsible for accidental food poisonings. The current study utilized an ELISA-based protein antibody microarray for the multiplexed detection of ten biothreat toxins, botulinum neurotoxins (BoNT) A, B, C, D, E, F, ricin, shiga toxins 1 and 2 (Stx), and staphylococcus enterotoxin B (SEB), in buffer and complex biological matrices. The multiplexed assay displayed a sensitivity of 1.3 pg/mL (BoNT/A, BoNT/B, SEB, Stx-1 and Stx-2), 3.3 pg/mL (BoNT/C, BoNT/E, BoNT/F) and 8.2 pg/mL (BoNT/D, ricin). All assays demonstrated high accuracy (75-120 percent recovery) and reproducibility (most coefficients of variation < 20%). Quantification curves for the ten toxins were also evaluated in clinical samples (serum, plasma, nasal fluid, saliva, stool, and urine) and environmental samples (apple juice, milk and baby food) with overall minimal matrix effects. The multiplex assays were highly specific, with little crossreactivity observed between the selected toxin antibodies. The results demonstrate a multiplex microarray that improves current immunoassay sensitivity for biological warfare agents in buffer, clinical, and environmental samples.

Physics based simulation of seismicity induced in the vicinity of a high-pressure fluid injection

Science.gov (United States)

McCloskey, J.; NicBhloscaidh, M.; Murphy, S.; O'Brien, G. S.; Bean, C. J.

2013-12-01

High-pressure fluid injection into subsurface is known, in some cases, to induce earthquakes in the surrounding volume. The increasing importance of ';fracking' as a potential source of hydrocarbons has made the seismic hazard from this effect an important issue the adjudication of planning applications and it is likely that poor understanding of the process will be used as justification of refusal of planning in Ireland and the UK. Here we attempt to understand some of the physical controls on the size and frequency of induced earthquakes using a physics-based simulation of the process and examine resulting earthquake catalogues The driver for seismicity in our simulations is identical to that used in the paper by Murphy et al. in this session. Fluid injection is simulated using pore fluid movement throughout a permeable layer from a high-pressure point source using a lattice Boltzmann scheme. Diffusivities and frictional parameters can be defined independently at individual nodes/cells allowing us to reproduce 3-D geological structures. Active faults in the model follow a fractal size distribution and exhibit characteristic event size, resulting in a power-law frequency-size distribution. The fluid injection is not hydraulically connected to the fault (i.e. fluid does not come into physical contact with the fault); however stress perturbations from the injection drive the seismicity model. The duration and pressure-time function of the fluid injection can be adjusted to model any given injection scenario and the rate of induced seismicity is controlled by the local structures and ambient stress field as well as by the stress perturbations resulting from the fluid injection. Results from the rate and state fault models of Murphy et al. are incorporated to include the effect of fault strengthening in seismically quite areas. Initial results show similarities with observed induced seismic catalogues. Seismicity is only induced where the active faults have not been

Structure of a bacterial toxin-activating acyltransferase.

Science.gov (United States)

Greene, Nicholas P; Crow, Allister; Hughes, Colin; Koronakis, Vassilis

2015-06-09

Secreted pore-forming toxins of pathogenic Gram-negative bacteria such as Escherichia coli hemolysin (HlyA) insert into host-cell membranes to subvert signal transduction and induce apoptosis and cell lysis. Unusually, these toxins are synthesized in an inactive form that requires posttranslational activation in the bacterial cytosol. We have previously shown that the activation mechanism is an acylation event directed by a specialized acyl-transferase that uses acyl carrier protein (ACP) to covalently link fatty acids, via an amide bond, to specific internal lysine residues of the protoxin. We now reveal the 2.15-Å resolution X-ray structure of the 172-aa ApxC, a toxin-activating acyl-transferase (TAAT) from pathogenic Actinobacillus pleuropneumoniae. This determination shows that bacterial TAATs are a structurally homologous family that, despite indiscernible sequence similarity, form a distinct branch of the Gcn5-like N-acetyl transferase (GNAT) superfamily of enzymes that typically use acyl-CoA to modify diverse bacterial, archaeal, and eukaryotic substrates. A combination of structural analysis, small angle X-ray scattering, mutagenesis, and cross-linking defined the solution state of TAATs, with intermonomer interactions mediated by an N-terminal α-helix. Superposition of ApxC with substrate-bound GNATs, and assay of toxin activation and binding of acyl-ACP and protoxin peptide substrates by mutated ApxC variants, indicates the enzyme active site to be a deep surface groove.

Effects of T-2 toxin on turkey herpesvirus–induced vaccinal immunity against Marek’s disease

Science.gov (United States)

T-2 toxin, a very potent immunotoxic Type A trichothecene, is a secondary metabolite produced primarily by Fusarium spp., which grows on cereal grains and can lead to contaminated livestock feed. Repeated exposure to T-2 toxin has been shown to cause immunosuppression and decrease the resistance of ...

Parenteral medium-chain triglyceride-induced neutrophil activation is not mediated by a Pertussis Toxin sensitive receptor.

Science.gov (United States)

Versleijen, Michelle W J; van Esterik, Joantine C J; Roelofs, Hennie M J; van Emst-de Vries, Sjenet E; Willems, Peter H G M; Wanten, Geert J A

2009-02-01

Lipid-induced immune modulation might contribute to the increased infection rate that is observed in patients using parenteral nutrition. We previously showed that emulsions containing medium-chain triglycerides (LCT/MCTs or pure MCTs), but not pure long-chain triglycerides (LCTs), impair neutrophil functions, modulate cell-signaling and induce neutrophil activation in vitro. It has recently been shown that medium-chain fatty acids are ligands for GPR84, a pertussis toxin (PT)-sensitive G-protein-coupled receptor (GPCR). This finding urged us to investigate whether MCT-induced neutrophil activation is mediated by PT-sensitive GPCRs. Neutrophils isolated from blood of healthy volunteers were pre-incubated with PT (0.5-1 microg/mL, 1.5 h) and analyzed for the effect of this pre-incubation on LCT/MCT (2.5 mmol/L)-dependent modulation of serum-treated zymosan (STZ)-induced intracellular Ca(2+) mobilization and on LCT/MCT (5 mmol/L)-induced expression of cell surface adhesion (CD11b) and degranulation (CD66b) markers and oxygen radical (ROS) production. PT did not inhibit the effects of LCT/MCT on the STZ-induced increase in cytosolic free Ca(2+) concentration. LCT/MCT increased ROS production to 146% of unstimulated cells. However, pre-incubation with PT did not inhibit the LCT/MCT-induced ROS production. Furthermore, the LCT/MCT-induced increase in CD11b and CD66b expression (196% and 235% of unstimulated cells, respectively) was not inhibited by pre-incubation with PT. LCT/MCT-induced neutrophil activation does not involve the action of a PT-sensitive G-protein-coupled receptor.

Complementary action of jasmonic acid on salicylic acid in mediating fungal elicitor-induced flavonol glycoside accumulation of Ginkgo biloba cells.

Science.gov (United States)

Xu, Maojun; Dong, Jufang; Wang, Huizhong; Huang, Luqi

2009-08-01

The antagonistic action between jasmonic acid (JA) and salicylic acid (SA) in plant defence responses has been well documented. However, their relationship in secondary metabolite production is largely unknown. Here, we report that PB90, a protein elicitor from Phytophthora boehmeriae, triggers JA generation, SA accumulation and flavonol glycoside production of Ginkgo biloba cells. JA inhibitors suppress not only PB90-triggered JA generation, but also the elicitor-induced flavonol glycoside production. However, the elicitor can still enhance flavonol glycoside production even though the JA generation is totally inhibited. Over-expression of SA hydrolase gene NahG not only abolishes SA accumulation, but also suppresses the elicitor-induced flavonol glycoside production when JA signalling is inhibited. Interestingly, expression of NahG does not inhibit the elicitor-induced flavonol glycoside accumulation in the absence of JA inhibitors. Moreover, JA levels are significantly enhanced when SA accumulation is impaired in the transgenic cells. Together, the data suggest that both JA and SA are involved in PB90-induced flavonol glycoside production. Furthermore, we demonstrate that JA signalling might be enhanced to substitute for SA to mediate the elicitor-induced flavonol glycoside accumulation when SA signalling is impaired, which reveals an unusual complementary relationship between JA and SA in mediating plant secondary metabolite production.

On the feasibility of inducing oil mobilization in existing reservoirs via wellbore harmonic fluid action

KAUST Repository

Jeong, Chanseok

2011-03-01

Although vibration-based mobilization of oil remaining in mature reservoirs is a promising low-cost method of enhanced oil recovery (EOR), research on its applicability at the reservoir scale is still at an early stage. In this paper, we use simplified models to study the potential for oil mobilization in homogeneous and fractured reservoirs, when harmonically oscillating fluids are injected/produced within a well. To this end, we investigate first whether waves, induced by fluid pressure oscillations at the well site, and propagating radially and away from the source in a homogeneous reservoir, could lead to oil droplet mobilization in the reservoir pore-space. We discuss both the fluid pore-pressure wave and the matrix elastic wave cases, as potential agents for increasing oil mobility. We then discuss the more realistic case of a fractured reservoir, where we study the fluid pore-pressure wave motion, while taking into account the leakage effect on the fracture wall. Numerical results show that, in homogeneous reservoirs, the rock-stress wave is a better energy-delivery agent than the fluid pore-pressure wave. However, neither the rock-stress wave nor the pore-pressure wave is likely to result in any significant residual oil mobilization at the reservoir scale. On the other hand, enhanced oil production from the fractured reservoir\\'s matrix zone, induced by cross-flow vibrations, appears to be feasible. In the fractured reservoir, the fluid pore-pressure wave is only weakly attenuated through the fractures, and thus could induce fluid exchange between the rock formation and the fracture space. The vibration-induced cross-flow is likely to improve the imbibition of water into the matrix zone and the expulsion of oil from it. © 2011 Elsevier B.V.

Blocking of leukocyte accumulation in the cerebrospinal fluid augments bacteremia and increases lethality in experimental pneumococcal meningitis

DEFF Research Database (Denmark)

Brandt, Christian T; Lundgren, Jens D; Frimodt-Møller, Niels

2005-01-01

, blocking leukocyte entry to the central nervous system in experimental pneumococcal meningitis compromises the survival prognosis but does not affect the risk of brain damage or level of infection in this compartment. Conversely, poorer prognosis was associated with an increase in bacterial load in blood......The role of leukocyte accumulation in the cerebrospinal fluid (CSF) in the evolution of the pathophysiological changes that occur in bacterial meningitis is unclear. Here, we investigate how leukocyte recruitment to the CSF, modulated by the leukocyte blocker fucoidin, affects the extent of brain......, suggesting that leukocyte blockage affects the host's ability to control systemic infection....

Polyamine toxins

DEFF Research Database (Denmark)

Strømgaard, Kristian; Jensen, Lars S; Vogensen, Stine B

2005-01-01

Polyamine toxins, isolated from spiders and wasps, have been used as pharmacological tools for the study of ionotropic receptors, but their use have so far been hampered by their lack of selectivity. In this mini-review, we describe how careful synthetic modification of native polyamine toxins ha...

Pertussis toxin-sensitive G-protein mediates the alpha 2-adrenergic receptor inhibition of melatonin release in photoreceptive chick pineal cell cultures

International Nuclear Information System (INIS)

Pratt, B.L.; Takahashi, J.S.

1988-01-01

The avian pineal gland is a photoreceptive organ that has been shown to contain postjunctional alpha 2-adrenoceptors that inhibit melatonin synthesis and/or release upon receptor activation. Physiological response and [32P]ADP ribosylation experiments were performed to investigate whether pertussis toxin-sensitive guanine nucleotide-binding proteins (G-proteins) were involved in the transduction of the alpha 2-adrenergic signal. For physiological response studies, the effects of pertussis toxin on melatonin release in dissociated cell cultures exposed to norepinephrine were assessed. Pertussis toxin blocked alpha 2-adrenergic receptor-mediated inhibition in a dose-dependent manner. Pertussis toxin-induced blockade appeared to be noncompetitive. One and 10 ng/ml doses of pertussis toxin partially blocked and a 100 ng/ml dose completely blocked norepinephrine-induced inhibition. Pertussis toxin-catalyzed [32P]ADP ribosylation of G-proteins in chick pineal cell membranes was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Membranes were prepared from cells that had been pretreated with 0, 1, 10, or 100 ng/ml pertussis toxin. In the absence of pertussis toxin pretreatment, two major proteins of 40K and 41K mol wt (Mr) were labeled by [32P]NAD. Pertussis toxin pretreatment of pineal cells abolished [32P] radiolabeling of the 40K Mr G-protein in a dose-dependent manner. The norepinephrine-induced inhibition of both cAMP efflux and melatonin release, as assessed by RIA of medium samples collected before membrane preparation, was also blocked in a dose-dependent manner by pertussis toxin. Collectively, these results suggest that a pertussis toxin-sensitive 40K Mr G-protein labeled by [32P]NAD may be functionally associated with alpha 2-adrenergic signal transduction in chick pineal cells

Enhanced vaginal drug delivery through the use of hypotonic formulations that induce fluid uptake

Science.gov (United States)

Ensign, Laura M.; Hoen, Timothy; Maisel, Katharina; Cone, Richard; Hanes, Justin

2013-01-01

Mucosal epithelia use osmotic gradients for fluid absorption and secretion. We hypothesized that administration of hypotonic solutions would induce fluid uptake that could be advantageous for rapidly delivering drugs through mucus to the vaginal epithelium. We found that hypotonic formulations markedly increased the rate at which small molecule drugs and muco-inert nanoparticles (mucus-penetrating particles, or MPP), but not conventional mucoadhesive nanparticles (CP), reached the vaginal epithelial surface in vivo in mice. Additionally, hypotonic formulations greatly enhanced drug and MPP delivery to the entire epithelial surface, including deep into the vaginal folds (rugae) that drugs or MPP in isotonic formulations failed to reach efficiently. However, hypotonic formulations caused unencapsulated “free” drugs to be drawn through the epithelium, reducing vaginal retention. In contrast, hypotonic formulations caused MPP to accumulate rapidly and uniformly on vaginal surfaces, ideally positioned for localized sustained drug delivery. Using a mouse model of vaginal genital herpes (HSV-2) infection, we found that hypotonic delivery of free drug led to improved immediate protection, but diminished longer-term protection. In contrast, as we previously demonstrated, hypotonic delivery of drug via MPP led to better long-term retention and protection in the vagina. Importantly, we demonstrate that slightly hypotonic formulations provided rapid and uniform delivery of MPP to the entire vaginal surface, thus enabling formulations with minimal risk of epithelial toxicity. Hypotonic formulations for vaginal drug delivery via MPP may significantly improve prevention and treatment of reproductive tract diseases and disorders. PMID:23769419

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

International Nuclear Information System (INIS)

Won, JaeSeon; Nam, PilWon; Lee, YongChan; Choe, MuHyeon

2009-01-01

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 4 S) between the Fab fragment and PE38 (38 kDa truncated form of Pseudomonas exotoxin A). The SWn sequence also harbored one cysteine residue that could form a disulfide bridge between two Fab-SWn-PE38 monomers. We assessed the cytotoxicity of the monovalent (Fab-SWn-PE38), and divalent ([Fab-SWn-PE38] 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.

Rapid Extraction and Identification of Maitotoxin and Ciguatoxin-Like Toxins from Caribbean and Pacific Gambierdiscus Using a New Functional Bioassay

OpenAIRE

Lewis, Richard J.; Inserra, Marco; Vetter, Irina; Holland, William C.; Hardison, D. Ransom; Tester, Patricia A.; Litaker, R. Wayne

2016-01-01

Background Ciguatera is a circumtropical disease produced by polyether sodium channel toxins (ciguatoxins) that enter the marine food chain and accumulate in otherwise edible fish. Ciguatoxins, as well as potent water-soluble polyethers known as maitotoxins, are produced by certain dinoflagellate species in the genus Gambierdiscus and Fukuyoa spp. in the Pacific but little is known of the potential of related Caribbean species to produce these toxins. Methods We established a simplified proce...

Role of Peptide YY3-36 and Glucose-Dependent Insulinotropic Polypeptide in Anorexia Induction by Trichothecences T-2 Toxin, HT-2 Toxin, Diacetoxyscirpenol, and Neosolaniol.

Science.gov (United States)

Zhang, Jie; Jia, Hui; Wang, Qingqing; Zhang, Yajie; Wu, Wenda; Zhang, Haibin

2017-09-01

Trichothecences, secondary metabolites produced by Fusarium, are serious health risks to humans and animals worldwide. Although type A trichothecence-induced food refusal has been observed, the mechanism underlying the anorexia caused by these compounds is not fully understood. In this study, we hypothesized that anorexia induced by type A trichothecenes, including T-2 toxin (T-2), HT-2 toxin (HT-2), diacetoxyscirpenol (DAS), and neosolaniol (NEO), in mice corresponds to the changes in the gut satiety hormones peptide YY3-36 (PYY3-36) and glucose-dependent insulinotropic polypeptide (GIP) in plasma. A well-characterized mouse food refusal model was used in this assay. Oral exposure to or intraperitoneal (ip) injection of 1 mg/kg bw T-2, HT-2, DAS, or NEO resulted in dramatically decreased food intake, and PYY3-36 and GIP concentrations were elevated accordingly. Specifically, the PYY3-36 and GIP concentrations peaked at 2 h following oral exposure to these 4 toxins individually, although the durations were not identical. After ip administration of T-2 or HT-2, PYY3-36 significantly increased within 6 h. However, no significant difference was found in the DAS and NEO groups. The GIP levels peaked within 2, 2, 0.5, and 0.5 h, respectively, and remained increased up to 6, 6, 2, and 6 h, respectively, following T-2, HT-2, DAS, or NEO ip exposure. The increase in GIP was greater than that of PYY3-36 after exposure to the 4 toxins using 2 administration routes. Together, these findings suggest that PYY3-36 and GIP play a role in T-2-, HT-2-, DAS-, and NEO-induced anorexia. © The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Progress on Botulinum Toxin Type A-Induced Pain Relief in the Field of Plastics.

Science.gov (United States)

Lu, Xiaona; Chen, Guocheng; Ren, Pengjie; Yang, Yan; Fan, Fei

2017-11-01

To retrospectively evaluate the effectiveness of Botulinum Toxin Type A (BTX-A) injections relieve pain in the field of plastic surgery and postoperative rehabilitation, and discuss the analgesic mechanism of BTX- A in plastics and related research progress. From appearance to September 1, 2016, PUBMED, EMBASE, and Web of Science were searched, using the key words related to "Botulinum Toxin Type A" and "Pain." Furtherly, nonplastic surgery-related literature was excluded by manual screening. Eleven literatures met the inclusion criteria, including 6 prospective controlled cohorts, 4 patient series, and 1 retrospective cohort. These studies involved Lower Limb, Breast, Hallux, Amputees, and Temporomandibular joint disk disfigurement and enrolled 402 patients. Among the patients, 360 received intraoperative BTX-A injection at the time of the main surgical procedure, 16 injected postoperatively and 26 did not undergo surgery. And 85.32% reported pain alleviation and 69.96% got favorable side effects and no one occurred major adverse effects. But 1.83% accepted injections more than once. Mechanism analysis explained these studies' results and demonstrated the analgesic effectiveness of BTX-A in plastics with nociceptive pain, inflammatory pain, and neuropathic pain. The results suggest that BTX-A may induce postoperative pain associated with plastic surgeries relief. But the available data of outcome assessment involved in this review are inconsistent and failed to meet methodological rigor. And pain alleviations are influenced by many factors. So further randomized controlled clinical trials with large sample sizes are needed to support this practice, determine standard usage methods, and establish corresponding specification systems.

Nanomechanical detection of cholera toxin using microcantilevers functionalized with ganglioside nanodiscs

Energy Technology Data Exchange (ETDEWEB)

Tark, Soo-Hyun; Dravid, Vinayak P [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Das, Aditi; Sligar, Stephen, E-mail: s-sligar@illinois.edu, E-mail: v-dravid@northwestern.edu [Department of Biochemistry and Chemistry, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

2010-10-29

The label-free detection of cholera toxin is demonstrated using microcantilevers functionalized with ganglioside nanodiscs. The cholera toxin molecules bind specifically to the active membrane protein encased in nanodiscs, nanoscale lipid bilayers surrounded by an amphipathic protein belt, immobilized on the cantilever surface. The specific molecular binding results in cantilever deflection via the formation of a surface stress-induced bending moment. The nanomechanical cantilever response is quantitatively monitored by optical interference. The consistent and reproducible nanomechanical detection of cholera toxin in nanomolar range concentrations is demonstrated. The results validated with such a model system suggest that the combination of a microcantilever platform with receptor nanodiscs is a promising approach for monitoring invasive pathogens and other types of biomolecular detection relevant to drug discovery.

Nanomechanical detection of cholera toxin using microcantilevers functionalized with ganglioside nanodiscs

International Nuclear Information System (INIS)

Tark, Soo-Hyun; Dravid, Vinayak P; Das, Aditi; Sligar, Stephen

2010-01-01

The label-free detection of cholera toxin is demonstrated using microcantilevers functionalized with ganglioside nanodiscs. The cholera toxin molecules bind specifically to the active membrane protein encased in nanodiscs, nanoscale lipid bilayers surrounded by an amphipathic protein belt, immobilized on the cantilever surface. The specific molecular binding results in cantilever deflection via the formation of a surface stress-induced bending moment. The nanomechanical cantilever response is quantitatively monitored by optical interference. The consistent and reproducible nanomechanical detection of cholera toxin in nanomolar range concentrations is demonstrated. The results validated with such a model system suggest that the combination of a microcantilever platform with receptor nanodiscs is a promising approach for monitoring invasive pathogens and other types of biomolecular detection relevant to drug discovery.

Autoproteolytic Activation of Bacterial Toxins

Directory of Open Access Journals (Sweden)

Aimee Shen

2010-05-01

Full Text Available Protease domains within toxins typically act as the primary effector domain within target cells. By contrast, the primary function of the cysteine protease domain (CPD in Multifunctional Autoprocessing RTX-like (MARTX and Clostridium sp. glucosylating toxin families is to proteolytically cleave the toxin and release its cognate effector domains. The CPD becomes activated upon binding to the eukaryotic-specific small molecule, inositol hexakisphosphate (InsP6, which is found abundantly in the eukaryotic cytosol. This property allows the CPD to spatially and temporally regulate toxin activation, making it a prime candidate for developing anti-toxin therapeutics. In this review, we summarize recent findings related to defining the regulation of toxin function by the CPD and the development of inhibitors to prevent CPD-mediated activation of bacterial toxins.

Phase coupling of a circadian neuropeptide with rest/activity rhythms detected using a membrane-tethered spider toxin.

Directory of Open Access Journals (Sweden)

Ying Wu

2008-11-01

induces rhythmic action potential bursts and depolarized plateau potentials. These in vitro and in vivo electrophysiological effects of membrane-tethered delta-ACTX-Hv1a are consistent with the effects of soluble delta-ACTX-Hv1a purified from venom on Na(+ channel physiological and biophysical properties in cockroach neurons. Membrane-tethered delta-ACTX-Hv1a expression in the PDF-secreting subset of clock neurons induces an approximately 4-h phase advance of the rhythm of PDF accumulation in their terminals relative to both the phase of the day:night cycle and the phase of the circadian transcriptional feedback loops. As a consequence, the morning anticipatory peak of locomotor activity preceding dawn, which has been shown to be driven by the clocks of the PDF-secreting subset of clock neurons, phase advances coordinately with the phase of the PDF rhythm of the PDF-secreting clock neurons, rather than maintaining its phase relationship with the day:night cycle and circadian transcriptional feedback loops. These results (1 validate the tethered-toxin technology for cell-autonomous modulation of ion channel biophysical properties in vivo in transgenic Drosophila, (2 demonstrate that the kinetics of para Na(+ channel inactivation is a key parameter for determining the phase relationship between circadian transcriptional feedback oscillation and PDF secretion, and (3 provide experimental support for the hypothesis that PDF-secreting clock neurons entrain the phase of organismal rhythms via the temporal patterning of secreted PDF signals.

Characterization of the maize lipoxygenase gene family in relation to aflatoxin accumulation resistance

Science.gov (United States)

Oluwaseun F. Ogunola; Leigh K. Hawkins; Erik Mylroie; Michael V. Kolomiets; Eli Borrego; Juliet D. Tang; Paul W. Williams; Marilyn L. Warburton

2017-01-01

Maize (Zea mays L.) is a globally important staple food crop prone to contamination by aflatoxin, a carcinogenic secondary metabolite produced by the fungus Aspergillus flavus. An efficient approach to reduce accumulation of aflatoxin is the development of germplasm resistant to colonization and toxin...

Warm temperature acclimation impacts metabolism of paralytic shellfish toxins from Alexandrium minutum in commercial oysters.

Science.gov (United States)

Farrell, Hazel; Seebacher, Frank; O'Connor, Wayne; Zammit, Anthony; Harwood, D Tim; Murray, Shauna

2015-09-01

Species of Alexandrium produce potent neurotoxins termed paralytic shellfish toxins and are expanding their ranges worldwide, concurrent with increases in sea surface temperature. The metabolism of molluscs is temperature dependent, and increases in ocean temperature may influence both the abundance and distribution of Alexandrium and the dynamics of toxin uptake and depuration in shellfish. Here, we conducted a large-scale study of the effect of temperature on the uptake and depuration of paralytic shellfish toxins in three commercial oysters (Saccostrea glomerata and diploid and triploid Crassostrea gigas, n = 252 per species/ploidy level). Oysters were acclimated to two constant temperatures, reflecting current and predicted climate scenarios (22 and 27 °C), and fed a diet including the paralytic shellfish toxin-producing species Alexandrium minutum. While the oysters fed on A. minutum in similar quantities, concentrations of the toxin analogue GTX1,4 were significantly lower in warm-acclimated S. glomerata and diploid C. gigas after 12 days. Following exposure to A. minutum, toxicity of triploid C. gigas was not affected by temperature. Generally, detoxification rates were reduced in warm-acclimated oysters. The routine metabolism of the oysters was not affected by the toxins, but a significant effect was found at a cellular level in diploid C. gigas. The increasing incidences of Alexandrium blooms worldwide are a challenge for shellfish food safety regulation. Our findings indicate that rising ocean temperatures may reduce paralytic shellfish toxin accumulation in two of the three oyster types; however, they may persist for longer periods in oyster tissue. © 2015 John Wiley & Sons Ltd.

Toxin-Based Therapeutic Approaches

Science.gov (United States)

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

The biphasic effect of extracellular glucose concentration on carbachol-induced fluid secretion from mouse submandibular glands.

Science.gov (United States)

Terachi, Momomi; Hirono, Chikara; Kitagawa, Michinori; Sugita, Makoto

2018-06-01

Cholinergic agonists evoke elevations of the cytoplasmic free-calcium concentration ([Ca 2+ ] i ) to stimulate fluid secretion in salivary glands. Salivary flow rates are significantly reduced in diabetic patients. However, it remains elusive how salivary secretion is impaired in diabetes. Here, we used an ex vivo submandibular gland perfusion technique to characterize the dependency of salivary flow rates on extracellular glucose concentration and activities of glucose transporters expressed in the glands. The cholinergic agonist carbachol (CCh) induced sustained fluid secretion, the rates of which were modulated by the extracellular glucose concentration in a biphasic manner. Both lowering the extracellular glucose concentration to less than 2.5 mM and elevating it to higher than 5 mM resulted in decreased CCh-induced fluid secretion. The CCh-induced salivary flow was suppressed by phlorizin, an inhibitor of the sodium-glucose cotransporter 1 (SGLT1) located basolaterally in submandibular acinar cells, which is altered at the protein expression level in diabetic animal models. Our data suggest that SGLT1-mediated glucose uptake in acinar cells is required to maintain the fluid secretion by sustaining Cl - secretion in real-time. High extracellular glucose levels may suppress the CCh-induced secretion of salivary fluid by altering the activities of ion channels and transporters downstream of [Ca 2+ ] i signals. © 2018 Eur J Oral Sci.

Patterns of gravity induced aggregate migration during casting of fluid concretes

DEFF Research Database (Denmark)

Spangenberg, Jon; Roussel, N.; Hattel, Jesper Henri

2012-01-01

In this paper, aggregate migration patterns during fluid concrete castings are studied through experiments, dimensionless approach and numerical modeling. The experimental results obtained on two beams show that gravity induced migration is primarily affecting the coarsest aggregates resulting in...

Affinity chromatography of tetanus toxin, tetanus toxoid, and botulinum A toxin on synaptosomes, and differentiation of their acceptors

Energy Technology Data Exchange (ETDEWEB)

Habermann, E [Giessen Univ. (Germany, F.R.). Pharmakologisches Inst.

1976-01-01

/sup 125/I-labelled tetanus toxin and /sup 125/I-labelled botulinum A neurotoxin are known to be specifically bound to brain synaptosomes. In order to discriminate between active toxin and inactive admixtures present in the starting material or arising during iodination, synaptosome columns were prepared using bromacetylcellulose and/or kieselgur (Celite) as carriers. Both types of columns adsorb the toxins from low ionic strength medium and release them if the pH and ionic strength are raised. Botulinum toxin was eluted with lower ionic strength than tetanus toxin, and could be freed from nontoxic admixtures. Analysis by affinity chromatography disclosed partially toxoided tetanus toxin in both labelled and unlabelled toxin samples. High concentrations of formaldehyde (0.5%) destroyed both toxicity and affinity to the synaptosomes of tetanus toxin. Low concentrations of formaldehyde (0.05%) yielded a derivative of low toxicity which was still, however less firmly, bound to synaptosomes. Tetanus and botulinum toxin differ by their acceptors. Whereas unlabelled botulinum toxin is unable to compete with labelled tetanus toxin, unlabelled tetanus toxin slightly competes with botulinum toxin. Both labelled toxins display anomalous binding behaviour in that they cannot be displaced completely even with a large excess of unlabelled toxin.

Affinity chromatography of tetanus toxin, tetanus toxoid, and botulinum A toxin on synaptosomes, and differentiation of their acceptors

International Nuclear Information System (INIS)

Habermann, E.

1976-01-01

125 I-labelled tetanus toxin and 125 I-labelled botulinum A neurotoxin are known to be specifically bound to brain synaptosomes. In order to discriminate between active toxin and inactive admixtures present in the starting material or arising during iodination, synaptosome columns were prepared using bromacetylcellulose and/or kieselgur (Celite) as carriers. Both types of columns adsorb the toxins from low ionic strength medium and release them if the pH and ionic strength are raised. Botulinum toxin was eluted with lower ionic strength than tetanus toxin, and could be freed from nontoxic admixtures. Analysis by affinity chromatography disclosed partially toxoided tetanus toxin in both labelled and unlabelled toxin samples. High concentrations of formaldehyde (0.5%) destroyed both toxicity and affinity to the synaptosomes of tetanus toxin. Low concentrations of formaldehyde (0.05%) yielded a derivative of low toxicity which was still, however less firmly, bound to synaptosomes. Tetanus and botulinum toxin differ by their acceptors. Whereas unlabelled botulinum toxin is unable to compete with labelled tetanus toxin, unlabelled tetanus toxin slightly competes with botulinum toxin. Both labelled toxins display anomalous binding behaviour in that they cannot be displaced completely even with a large excess of unlabelled toxin. (orig.) [de

Cadmium-induced physiological response and antioxidant enzyme changes in the novel cadmium accumulator, Tagetes patula

Energy Technology Data Exchange (ETDEWEB)

Liu, Yu-Ting; Chen, Zueng-Sang [Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan (China); Hong, Chwan-Yang, E-mail: cyhong@ntu.edu.tw [Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan (China)

2011-05-30

The accumulation and effect of cadmium (Cd) on the growth and enzymatic activities changes of antioxidants in Tagetes patula, French marigold, were investigated to reveal the physiological mechanisms corresponding to its Cd tolerance and accumulation. Hydroponically grown T. patula plants were treated with different concentrations of Cd (0, 10, 25, 50 {mu}M CdCl{sub 2}) at various regime of times. T. patula accumulated Cd to a maximum of 450 mg Cd kg{sup -1} dry weight (DW) in shoot and 3500 mg Cd kg{sup -1} DW in root after 14 days' exposure at 10 and 50 {mu}M CdCl{sub 2}, respectively. The translocation factors of Cd were greater than 1 in plants exposed to 10 {mu}M CdCl{sub 2}. Toxic effects were gradually observed with increasing Cd concentration (25 and 50 {mu}M) accompanied with the reduction of biomass, chlorophyll content, decrease of cell viability and the increase level of lipid peroxidation. In leaves of T. patula, the activities of ascorbate peroxidase (APX), glutathione reductase (GR) and superoxide dismutase (SOD) were induced by Cd. However, in roots, activities of APX, GR, SOD and catalase (CAT) were significantly reduced by 25 and 50 {mu}M Cd treatment but not 10 {mu}M Cd. In-gel zymography analysis revealed that Cd induced the enzymatic activities of APX, MnSOD, CuZnSOD and different isozymes of GR in leaves. These results indicate that T. patula is a novel Cd accumulator and able to tolerate with Cd-induced toxicity by activation of its antioxidative defense system.

Cadmium-induced physiological response and antioxidant enzyme changes in the novel cadmium accumulator, Tagetes patula

International Nuclear Information System (INIS)

Liu, Yu-Ting; Chen, Zueng-Sang; Hong, Chwan-Yang

2011-01-01

The accumulation and effect of cadmium (Cd) on the growth and enzymatic activities changes of antioxidants in Tagetes patula, French marigold, were investigated to reveal the physiological mechanisms corresponding to its Cd tolerance and accumulation. Hydroponically grown T. patula plants were treated with different concentrations of Cd (0, 10, 25, 50 μM CdCl 2 ) at various regime of times. T. patula accumulated Cd to a maximum of 450 mg Cd kg -1 dry weight (DW) in shoot and 3500 mg Cd kg -1 DW in root after 14 days' exposure at 10 and 50 μM CdCl 2 , respectively. The translocation factors of Cd were greater than 1 in plants exposed to 10 μM CdCl 2 . Toxic effects were gradually observed with increasing Cd concentration (25 and 50 μM) accompanied with the reduction of biomass, chlorophyll content, decrease of cell viability and the increase level of lipid peroxidation. In leaves of T. patula, the activities of ascorbate peroxidase (APX), glutathione reductase (GR) and superoxide dismutase (SOD) were induced by Cd. However, in roots, activities of APX, GR, SOD and catalase (CAT) were significantly reduced by 25 and 50 μM Cd treatment but not 10 μM Cd. In-gel zymography analysis revealed that Cd induced the enzymatic activities of APX, MnSOD, CuZnSOD and different isozymes of GR in leaves. These results indicate that T. patula is a novel Cd accumulator and able to tolerate with Cd-induced toxicity by activation of its antioxidative defense system.

Development of bubble-induced turbulence model for advanced two-fluid model

International Nuclear Information System (INIS)

Hosoi, Hideaki; Yoshida, Hiroyuki

2011-01-01

A two-fluid model can simulate two-phase flow by computational cost less than detailed two-phase flow simulation method such as interface tracking method. The two-fluid model is therefore useful for thermal hydraulic analysis in the large-scale domain such as rod bundles. However, since the two-fluid model includes a lot of constitutive equations verified by use of experimental results, it has problems that the result of analyses depends on accuracy of the constitutive equations. To solve these problems, an advanced two-fluid model has been developed by Japan Atomic Energy Agency. In this model, interface tracking method is combined with two-fluid model to accurately predict large interface structure behavior. Liquid clusters and bubbles larger than a computational cell are calculated using the interface tracking method, and those smaller than the cell are simulated by the two-fluid model. The constitutive equations to evaluate the effects of small bubbles or droplets on two-phase flow are also required in the advanced two-fluid model, just as with the conventional two-fluid model. However, the dependency of small bubbles and droplets on two-phase flow characteristics is relatively small, and fewer experimental results are required to verify the characteristics of large interface structures. Turbulent dispersion force model is one of the most important constitutive equations for the advanced two-fluid model. The turbulent dispersion force model has been developed by many researchers for the conventional two-fluid model. However, existing models implicitly include the effects of large bubbles and the deformation of bubbles, and are unfortunately not applicable to the advanced two-fluid model. In the previous study, the authors suggested the turbulent dispersion force model based on the analogy of Brownian motion. And the authors improved the turbulent dispersion force model in consideration of bubble-induced turbulence to improve the analysis results for small

Investigation of inactivation of Clostridium botulinum toxin by nuclear radiation. Final report. Untersuchung zur Desaktivierung des Clostridium botulinum Toxins durch Kernstrahlung. Endbericht

Energy Technology Data Exchange (ETDEWEB)

Kaltenhaeuser, A.; Werner, K.H.

1989-01-01

The effect of nuclear radiation on the toxicity and the molecular structure of the toxin produced by the microorganism Clostridium botulinum type A was investigated. The radiation induced changes in the structure of the toxin molecule. This effect is influenced by the composition or the medium above the toxin solution as well as by the temperature during the irradiation. The results of the investigation indicate that with increasing irradiation dose a new molecule was formed with immunological properties similar to the properties of the original molecule however with a greater molecular weight. After exposure to a radiation dose of 3,4 Mrad at normal temperature in air, complete detoxification of the substance was found. Immunizing experiments with the toxoid with two guinea-pigs indicated a pronounced increase of the antibody titer in the serum after 4 weeks. Vaccination experiments with the toxoid on animals show, that the protection against the effect of the toxin corresponds to the demands of the European Pharmacopoeia. The efficiency of the toxoid shows a similar efficiency as toxoids produced by chemical methods. The production of a toxoid-viccine with the relatively simple method of nuclear radiation appears possible. (orig./MG) With 12 refs., 3 tabs., 11 figs.

Toxin-Based Therapeutic Approaches

Directory of Open Access Journals (Sweden)

Itai Benhar

2010-10-01

Full Text Available 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.

Sphincter of Oddi botulinum toxin injection to prevent pancreatic fistula after distal pancreatectomy.

Science.gov (United States)

Hackert, Thilo; Klaiber, Ulla; Hinz, Ulf; Kehayova, Tzveta; Probst, Pascal; Knebel, Phillip; Diener, Markus K; Schneider, Lutz; Strobel, Oliver; Michalski, Christoph W; Ulrich, Alexis; Sauer, Peter; Büchler, Markus W

2017-05-01

Postoperative pancreatic fistula represents the most important complication after distal pancreatectomy. The aim of this study was to evaluate the use of a preoperative endoscopic injection of botulinum toxin into the sphincter of Oddi to prevent postoperative pancreatic fistula (German Clinical Trials Register number: DRKS00007885). This was an investigator-initiated, prospective clinical phase I/II trial with an exploratory study design. We included patients who underwent preoperative endoscopic sphincter botulinum toxin injection (100 units of Botox). End points were the feasibility, safety, and postoperative outcomes, including postoperative pancreatic fistula within 30 days after distal pancreatectomy. Botulinum toxin patients were compared with a control collective of patients undergoing distal pancreatectomy without botulinum toxin injection by case-control matching in a 1:1 ratio. Between February 2015 and February 2016, 29 patients were included. All patients underwent successful sphincter of Oddi botulinum toxin injection within a median of 6 (range 0-10) days before operation. One patient had an asymptomatic, self-limiting (48 hours) increase in serum amylase and lipase after injection. Distal pancreatectomy was performed in 24/29 patients; 5 patients were not resectable. Of the patients receiving botulinum toxin, 7 (29%) had increased amylase levels in drainage fluid on postoperative day 3 (the International Study Group of Pancreatic Surgery definition of postoperative pancreatic fistula grade A) without symptoms or need for reintervention. Importantly, no clinically relevant fistulas (International Study Group of Pancreatic Surgery grades B/C) were observed in botulinum toxin patients compared to 33% postoperative pancreatic fistula grade B/C in case-control patients (P botulinum toxin injection is a novel and safe approach to decrease the incidence of clinically relevant postoperative pancreatic fistula after distal pancreatectomy. The results of

Human mannose-binding lectin inhibitor prevents Shiga toxin-induced renal injury

DEFF Research Database (Denmark)

Ozaki, Masayuki; Kang, Yulin; Tan, Ying Siow

2016-01-01

Hemolytic uremic syndrome caused by Shiga toxin-producing Escherichia coli (STEC HUS) is a worldwide endemic problem, and its pathophysiology is not fully elucidated. Here we tested whether the mannose-binding lectin (MBL2), an initiating factor of lectin complement pathway activation, plays a cr...

Remarkable difference in paralytic shellfish poisoning toxin distribution in tissues of pen shell atrina pectinata exposed to toxic red tide bloom

International Nuclear Information System (INIS)

Narceda, Ronald Jefferson A.; Montojo, Ulysses M.; Cayme, Mirriam F.; Borja, Valeriano M.

2011-01-01

Pen shell atrina pectinata is one of the commercially important bivalves in Western Pacific region. In the Philippines, it is marketed as a whole meat or processed by shellfish harvesters to separate the abductor muscle as an export commodity. During blooms of toxic dinoflagellate pyrodinium bahamense var. compressum (Pbc), A. pectinata accumulates paralytic shellfish poisoning (PSP) toxins sometimes exceeding Philippine regulatory limit of 60μgSTXeq/100g tissue and international regulatory limit of 80μgSTXeq/100g tissue for safe human consumption, based on whole tissue analysis. Toxic blooms directly affect the shellfish industry which includes A. pectinata, and this causes not only significant economical losses on shellfish gatherers but also serious public health concerns. In this study, samples of A. pectinata exposed to toxic bloom of Pbc were collected in Sorsogon Bay, Philippines. Bioaccumulation and distribution of PSP toxins were determined in different tissues namely, abductor muscle, mantle, gills, gonads, siphon, stomach and intestine using High Performance Liquid Chromatography post column derivatization method with fluorescence detection. Likewise, green mussels Perna viridis being the sentinel species for PSP monitoring in the Philippines were also collected in the same area and served as control. Interestingly, results showed that the abductor muscle accumulates minimal level of PSP toxins and is several folds lower than the Philippine and international regulatory limits in contrast with the results obtained from P. viridis. Mantle parts showed toxicity values exceeding local regulatory limit and near to go beyond the international regulatory limit. Conversely, the remaining parts showed high toxicity values surpassing both regulation limits. Standard mouse bioassay regulatory used in PSP monitoring in the Philippines was also performed and revealed that the abductor muscle had non-detectable level of toxins. Also, toxicity values from different

Diphtheria Toxin-Induced Cell Death Triggers Wnt-Dependent Hair Cell Regeneration in Neonatal Mice.

Science.gov (United States)

Hu, Lingxiang; Lu, Jingrong; Chiang, Hao; Wu, Hao; Edge, Albert S B; Shi, Fuxin

2016-09-07

Cochlear hair cells (HCs), the sensory cells that respond to sound, do not regenerate after damage in adult mammals, and their loss is a major cause of deafness. Here we show that HC regeneration in newborn mouse ears occurred spontaneously when the original cells were ablated by treatment with diphtheria toxin (DT) in ears that had been engineered to overexpress the DT receptor, but was not detectable when HCs were ablated in vivo by the aminoglycoside antibiotic neomycin. A variety of Wnts (Wnt1, Wnt2, Wnt2b, Wnt4, Wnt5a, Wnt7b, Wnt9a, Wnt9b, and Wnt11) and Wnt pathway component Krm2 were upregulated after DT damage. Nuclear β-catenin was upregulated in HCs and supporting cells of the DT-damaged cochlea. Pharmacological inhibition of Wnt decreased spontaneous regeneration, confirming a role of Wnt signaling in HC regeneration. Inhibition of Notch signaling further potentiated supporting cell proliferation and HC differentiation that occurred spontaneously. The absence of new HCs in the neomycin ears was correlated to less robust Wnt pathway activation, but the ears subjected to neomycin treatment nonetheless showed increased cell division and HC differentiation after subsequent forced upregulation of β-catenin. These studies suggest, first, that Wnt signaling plays a key role in regeneration, and, second, that the outcome of a regenerative response to damage in the newborn cochlea is determined by reaching a threshold level of Wnt signaling rather than its complete absence or presence. Sensory HCs of the inner ear do not regenerate in the adult, and their loss is a major cause of deafness. We found that HCs regenerated spontaneously in the newborn mouse after diphtheria toxin (DT)-induced, but not neomycin-induced, HC death. Regeneration depended on activation of Wnt signaling, and regeneration in DT-treated ears correlated to a higher level of Wnt activation than occurred in nonregenerating neomycin-treated ears. This is significant because insufficient

An extract of lionfish (Pterois volitans) spine tissue contains acetylcholine and a toxin that affects neuromuscular transmission.

Science.gov (United States)

Cohen, A S; Olek, A J

1989-01-01

A soluble toxic extract derived from spine tissue of the lionfish (Pterois volitans) decreased heart rate and force of contraction in isolated clam and frog hearts. These actions were due to the presence of micromolar concentrations of acetylcholine in the extract. Toxicity was retained after hydrolysis of acetylcholine by exogenous acetylcholinesterase, but heart function was no longer affected. Toxin treated in this way induced muscle fibrillation in an isolated nerve-muscle preparation, followed by blockade of neuromuscular transmission. Bursts of transient depolarizations were recorded at the muscle endplate shortly after toxin addition that correlated in time with the duration of toxin-induced muscle fibrillation. These effects are thought to be due to the increased release and then depletion of acetylcholine from the nerve terminal.

Heat-induced accumulation and futile cycling of trehalose in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Hottiger, T.; Schmutz, P.; Wiemken, A.

1987-01-01

Heat shock resulted in rapid accumulation of large amounts of trehalose in Saccharomyces cerevisiae. In cultures growing exponentially on glucose, the trehalose content of the cells increased from 0.01 to 1 g/g of protein within 1 h after the incubation temperature was shifted from 27 to 40 0 C. When the temperature was readjusted to 27 0 C, the accumulated trehalose was rapidly degraded. In parallel, the activity of the trehalose-phosphate synthase, the key enzyme of trehalose biosynthesis, increased about six fold during the heat shock and declined to normal level after readjustment of the temperature. Surprisingly, the activity of neutral trehalase, the key enzyme of trehalose degradation, also increased about threefold during the heat shock and remained almost constant during recovery of the cells at 27 0 C. In pulse-labeling experiments with [ 14 C] glucose, trehalose was found to be turned over rapidly in heat-shocked cells, indicating that both anabolic and catabolic enzymes of trehalose metabolism were active in vivo. Possible functions of the heat-induced accumulation of trehalose and its rapid turnover in an apparently futile cycle during heat shock are discussed

Fluid-Induced Vibration Analysis for Reactor Internals Using Computational FSI Method

Energy Technology Data Exchange (ETDEWEB)

Moon, Jong Sung; Yi, Kun Woo; Sung, Ki Kwang; Im, In Young; Choi, Taek Sang [KEPCO E and C, Daejeon (Korea, Republic of)

2013-10-15

This paper introduces a fluid-induced vibration analysis method which calculates the response of the RVI to both deterministic and random loads at once and utilizes more realistic pressure distribution using the computational Fluid Structure Interaction (FSI) method. As addressed above, the FIV analysis for the RVI was carried out using the computational FSI method. This method calculates the response to deterministic and random turbulence loads at once. This method is also a simple and integrative method to get structural dynamic responses of reactor internals to various flow-induced loads. Because the analysis of this paper omitted the bypass flow region and Inner Barrel Assembly (IBA) due to the limitation of computer resources, it is necessary to find an effective way to consider all regions in the RV for the FIV analysis in the future. Reactor coolant flow makes Reactor Vessel Internals (RVI) vibrate and may affect the structural integrity of them. U. S. NRC Regulatory Guide 1.20 requires the Comprehensive Vibration Assessment Program (CVAP) to verify the structural integrity of the RVI for Fluid-Induced Vibration (FIV). The hydraulic forces on the RVI of OPR1000 and APR1400 were computed from the hydraulic formulas and the CVAP measurements in Palo Verde Unit 1 and Yonggwang Unit 4 for the structural vibration analyses. In this method, the hydraulic forces were divided into deterministic and random turbulence loads and were used for the excitation forces of the separate structural analyses. These forces are applied to the finite element model and the responses to them were combined into the resultant stresses.

Coping with earthquakes induced by fluid injection

Science.gov (United States)

McGarr, Arthur F.; Bekins, Barbara; Burkardt, Nina; Dewey, James W.; Earle, Paul S.; Ellsworth, William L.; Ge, Shemin; Hickman, Stephen H.; Holland, Austin F.; Majer, Ernest; Rubinstein, Justin L.; Sheehan, Anne

2015-01-01

Large areas of the United States long considered geologically stable with little or no detected seismicity have recently become seismically active. The increase in earthquake activity began in the mid-continent starting in 2001 (1) and has continued to rise. In 2014, the rate of occurrence of earthquakes with magnitudes (M) of 3 and greater in Oklahoma exceeded that in California (see the figure). This elevated activity includes larger earthquakes, several with M > 5, that have caused significant damage (2, 3). To a large extent, the increasing rate of earthquakes in the mid-continent is due to fluid-injection activities used in modern energy production (1, 4, 5). We explore potential avenues for mitigating effects of induced seismicity. Although the United States is our focus here, Canada, China, the UK, and others confront similar problems associated with oil and gas production, whereas quakes induced by geothermal activities affect Switzerland, Germany, and others.

Botulinum Toxin (Botox) for Facial Wrinkles

Science.gov (United States)

... Stories Español Eye Health / Eye Health A-Z Botulinum Toxin (Botox) for Facial Wrinkles Sections Botulinum Toxin (Botox) ... Facial Wrinkles How Does Botulinum Toxin (Botox) Work? Botulinum Toxin (Botox) for Facial Wrinkles Leer en Español: La ...

Gold nanomaterials for the selective capturing and SERS diagnosis of toxins in aqueous and biological fluids

DEFF Research Database (Denmark)

Hassanain, Waleed A.; Izake, Emad L.; Schmidt, Michael Stenbæk

2017-01-01

the extractor nanoparticles within 5min by manipulating the pH environment of the nanoparticles. The regenerated extractor nanoparticles maintained their capture efficiency and, therefore, were re-used to capture of MC-LR from successive samples. The released purified toxin was screened within 10min on gold......A highly sensitive nanosensing method for the combined selective capture and SERS detection of Microcystin-LR (MC-LR) in blood plasma has been developed. The new method utilizes gold coated magnetic nanoparticles that are functionalized with anti MC-LR antibody Fab' fragments for the selective...... capture of MC-LR from aqueous media and blood plasma. Using an oriented immobilization approach, the Fab' fragments are covalently attached to gold surface to form a monolayer with high capture efficiency towards the toxin. After the selective capture, the purified MC-LR molecules were released from...

Impact of induced magnetic field on synovial fluid with peristaltic flow in an asymmetric channel

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Afsar Khan, Ambreen; Farooq, Arfa; Vafai, Kambiz

2018-01-01

In this paper, we have worked for the impact of induced magnetic field on peristaltic motion of a non-Newtonian, incompressible, synovial fluid in an asymmetric channel. We have solved the problem for two models, Model-1 which behaves as shear thinning fluid and Model-2 which behaves as shear thickening fluid. The problem is solved by using modified Adomian Decomposition method. It has seen that two models behave quite opposite to each other for some parameters. The impact of various parameters on u, dp/dx, Δp and induced magnetic field bx have been studied graphically. The significant findings of this study is that the size of the trapped bolus and the pressure gradient increases by increasing M for both models.

Lymphocyte receptors for pertussis toxin

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Clark, C.G.; Armstrong, G.D. (Univ. of Alberta, Edmonton (Canada))

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, and Jurkat cells. In all three cell systems, the pertussis toxin affinity probe specifically labeled a single protein species with an apparent molecular weight of 70,000 that was not observed when the procedure was performed in the presence of excess unmodified pertussis toxin. A protein comparable in molecular weight to the one detected by the photoaffinity labeling technique was also observed among the species that bound to pertussis toxin-agarose. The results suggest that pertussis toxin may bind to a 70,000-Da receptor in human T lymphocytes.

Botulinum toxin: bioweapon & magic drug.

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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.

Science.gov (United States)

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.

A Quantitative Electrochemiluminescence Assay for Clostridium perfringens alpha toxin

Science.gov (United States)

2006-08-10

Doyle, L.R. Beuchat, T.J. Montville (Eds.), Food Microbiology : Fundamentals and Fron- tiers, Second ed., ASM Press, Washington, D.C., 2001, pp. 351...D.E. Lorant, A.E. Bryant, G.A. Zimmerman, T.M. McIn- tyre, D.L. Stevens, S.M. Prescott , Alpha toxin from Clostridium per- fringens induces

Conservative fluid management prevents age-associated ventilator induced mortality.

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Herbert, Joseph A; Valentine, Michael S; Saravanan, Nivi; Schneck, Matthew B; Pidaparti, Ramana; Fowler, Alpha A; Reynolds, Angela M; Heise, Rebecca L

2016-08-01

Approximately 800 thousand patients require mechanical ventilation in the United States annually with an in-hospital mortality rate of over 30%. The majority of patients requiring mechanical ventilation are over the age of 65 and advanced age is known to increase the severity of ventilator-induced lung injury (VILI) and in-hospital mortality rates. However, the mechanisms which predispose aging ventilator patients to increased mortality rates are not fully understood. Ventilation with conservative fluid management decreases mortality rates in acute respiratory distress patients, but to date there has been no investigation of the effect of conservative fluid management on VILI and ventilator associated mortality rates. We hypothesized that age-associated increases in susceptibility and incidence of pulmonary edema strongly promote age-related increases in ventilator associated mortality. 2month old and 20month old male C57BL6 mice were mechanically ventilated with either high tidal volume (HVT) or low tidal volume (LVT) for up to 4h with either liberal or conservative fluid support. During ventilation, lung compliance, total lung capacity, and hysteresis curves were quantified. Following ventilation, bronchoalveolar lavage fluid was analyzed for total protein content and inflammatory cell infiltration. Wet to dry ratios were used to directly measure edema in excised lungs. Lung histology was performed to quantify alveolar barrier damage/destruction. Age matched non-ventilated mice were used as controls. At 4h, both advanced age and HVT ventilation significantly increased markers of inflammation and injury, degraded pulmonary mechanics, and decreased survival rates. Conservative fluid support significantly diminished pulmonary edema and improved pulmonary mechanics by 1h in advanced age HVT subjects. In 4h ventilations, conservative fluid support significantly diminished pulmonary edema, improved lung mechanics, and resulted in significantly lower mortality rates in

Numerical simulation of an elementary Vortex-Induced-Vibration problem by using fully-coupled fluid solid system computation

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M Pomarède

2016-09-01

Full Text Available Numerical simulation of Vortex-Induced-Vibrations (VIV of a rigid circular elastically-mounted cylinder submitted to a fluid cross-flow has been extensively studied over the past decades, both experimentally and numerically, because of its theoretical and practical interest for understanding Flow-Induced-Vibrations (FIV problems. In this context, the present article aims to expose a numerical study based on fully-coupled fluid-solid computations compared to previously published work [34], [36]. The computational procedure relies on a partitioned method ensuring the coupling between fluid and structure solvers. The fluid solver involves a moving mesh formulation for simulation of the fluid structure interface motion. Energy exchanges between fluid and solid models are ensured through convenient numerical schemes. The present study is devoted to a low Reynolds number configuration. Cylinder motion magnitude, hydrodynamic forces, oscillation frequency and fluid vortex shedding modes are investigated and the “lock-in” phenomenon is reproduced numerically. These numerical results are proposed for code validation purposes before investigating larger industrial applications such as configurations involving tube arrays under cross-flows [4].

Gut satiety hormones cholecystokinin and glucagon-like Peptide-17-36 amide mediate anorexia induction by trichothecenes T-2 toxin, HT-2 toxin, diacetoxyscirpenol and neosolaniol.

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Zhang, Jie; Liu, Shengli; Zhang, Hua; Li, Yuanyuan; Wu, Wenda; Zhang, Haibin

2017-11-15

The food-borne trichothecene mycotoxins have been documented to cause human and animal food poisoning. Anorexia is a hallmark of the trichothecene mycotoxins-induced adverse effects. Type B trichothecenes have been previously demonstrated to elicit robust anorectic responses, and this response has been directly linked to secretion of the gut satiety hormones cholecystokinin (CCK) and glucagon-like peptide-1 7-36 amide (GLP-1). However, less is known about the anorectic effects and underlying mechanisms of the type A trichothecenes, including T-2 toxin (T-2), HT-2 toxin (HT-2), diacetoxyscirpenol (DAS), neosolaniol (NEO). The purpose of this study was to relate type A trichothecenes T-2, HT-2, DAS and NEO-induced anorectic response to changes plasma concentrations of CCK and GLP-1. Following both oral gavage and intraperitoneal (IP) administration of 1mg/kg bw T-2, HT-2, DAS and NEO evoked robust anorectic response and secretion of CCK and GLP-1. Elevations of plasma CCK markedly corresponded to anorexia induction by T-2, HT-2, DAS and NEO. Following oral exposure, plasma CCK was peaked at 6h, 6h, 2h, 2h and lasted up to 24h, 24h, > 6h, > 6h for T-2, HT-2, DAS and NEO, respectively. IP exposed to four toxins all induced elevation of CCK with peak point and duration at 6h and >24h, respectively. In contrast to CCK, GLP-1 was moderately elevated by these toxins. Following both oral and IP exposure, T-2 and HT-2 evoked plasma GLP-1 elevation with peak point and duration at 2h and 6h, respectively. Plasma GLP-1 was peaked at 2h and still increased at 6h for IP and oral administration with DAS and NEO, respectively. In conclusion, CCK plays a contributory role in anorexia induction but GLP-1 might play a lesser role in this response. Copyright © 2017 Elsevier Inc. All rights reserved.

Temporal course of cerebrospinal fluid dynamics and amyloid accumulation in the aging rat brain from three to thirty months

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Chiu Catherine

2012-01-01

Full Text Available Abstract Background Amyloid accumulation in the brain parenchyma is a hallmark of Alzheimer's disease (AD and is seen in normal aging. Alterations in cerebrospinal fluid (CSF dynamics are also associated with normal aging and AD. This study analyzed CSF volume, production and turnover rate in relation to amyloid-beta peptide (Aβ accumulation in the aging rat brain. Methods Aging Fischer 344/Brown-Norway hybrid rats at 3, 12, 20, and 30 months were studied. CSF production was measured by ventriculo-cisternal perfusion with blue dextran in artificial CSF; CSF volume by MRI; and CSF turnover rate by dividing the CSF production rate by the volume of the CSF space. Aβ40 and Aβ42 concentrations in the cortex and hippocampus were measured by ELISA. Results There was a significant linear increase in total cranial CSF volume with age: 3-20 months (p p p p -1 to 12 months (11.30 day-1 and then a decrease to 20 months (10.23 day-1 and 30 months (6.62 day-1. Aβ40 and Aβ42 concentrations in brain increased from 3-30 months (p Conclusions In young rats there is no correlation between CSF turnover and Aβ brain concentrations. After 12 months, CSF turnover decreases as brain Aβ continues to accumulate. This decrease in CSF turnover rate may be one of several clearance pathway alterations that influence age-related accumulation of brain amyloid.

Action of cholera toxin in the intestinal epithelial cells

International Nuclear Information System (INIS)

Hyun, C.S.

1982-01-01

The primary event in the action of cholera toxin on the isolated chick intestinal epithelial cell is its interaction with the cell membrane. This involves a large number (17 million per cell) of high affinity binding sites which belong to a single class. Binding of biologically active 125 I-labeled toxin is rapid, temperature-dependent, reversible, and saturable over a wide range of concentrations and includes only a small contribution from nonspecific sites. A characteristic lag phase of 10 min occurs following the complete binding of toxin before any increase in cellular cAMP levels can be detected in the isolated cells. The response (elevation of cellular cAMP) of the enterocytes to cholera toxin is linear with time for 40-50 min and causes a six- to eight-fold increase over control levels at steady stae. cAMP and agents that increase cAMP production inhibit Cl - -independent Na + influx into the isolated enterocytes whereas chlorporomazine (CPZ) which completely abolishes toxin-induced elevation of cAMP both reverses and prevents the cAMP-mediated inhibition of Na + entry. Correlation between cellular cAMP levels and the magnitude of Na + influx into the enterocytes provides evidence for a cAMP-mediated control of intestinal Na + uptake, which may represent the mechanistic basis for the antiabsorptive effect of CT and Na + during induction of intestinal secretion. The effect of cAMP on Na + but no Cl - influx in our villus cell preparation can be partially explained in terms of a cAMP-regulated Na + /H + neutral exchange system

The Biology of the Cytolethal Distending Toxins

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Teresa Frisan

2011-03-01

Full Text Available The cytolethal distending toxins (CDTs, produced by a variety of Gram-negative pathogenic bacteria, are the first bacterial genotoxins described, since they cause DNA damage in the target cells. CDT is an A-B2 toxin, where the CdtA and CdtC subunits are required to mediate the binding on the surface of the target cells, allowing internalization of the active CdtB subunit, which is functionally homologous to the mammalian deoxyribonuclease I. The nature of the surface receptor is still poorly characterized, however binding of CDT requires intact lipid rafts, and its internalization occurs via dynamin-dependent endocytosis. The toxin is retrograde transported through the Golgi complex and the endoplasmic reticulum, and subsequently translocated into the nuclear compartment, where it exerts the toxic activity. Cellular intoxication induces DNA damage and activation of the DNA damage responses, which results in arrest of the target cells in the G1 and/or G2 phases of the cell cycle and activation of DNA repair mechanisms. Cells that fail to repair the damage will senesce or undergo apoptosis. This review will focus on the well-characterized aspects of the CDT biology and discuss the questions that still remain unanswered.

Protracted fluid-induced melting during Barrovian metamorphism in the Central Alps

DEFF Research Database (Denmark)

Rubatto, Daniela; Hermann, Jörg; Berger, Alfons

2009-01-01

that repeated melting events occurred within a single Barrovian metamorphic cycle at roughly constant temperature; that in the country rocks zircon formation was limited to the initial stages of melting, whereas further melting concentrated in the segregated leucosomes; that melting occurred at different times......The timing and dynamics of fluid-induced melting in the typical Barrovian sequence of the Central Alps has been investigated using zircon chronology and trace element composition. Multiple zircon domains in leucosomes and country rocks yield U-Pb ages spanning from ~32 to 22 Ma. The zircon formed...... in samples a few meters apart because of the local rock composition and localized influx of the fluids; and that leucosomes were repeatedly melted when fluids became available. The geochronological data force a revision of the temperature-time path of the migmatite belt in the Central Alps. Protracted...

Effect of pertussis toxin pretreated centrally on blood glucose level induced by stress.

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Suh, Hong-Won; Sim, Yun-Beom; Park, Soo-Hyun; Sharma, Naveen; Im, Hyun-Ju; Hong, Jae-Seung

2016-09-01

In the present study, we examined the effect of pertussis toxin (PTX) administered centrally in a variety of stress-induced blood glucose level. Mice were exposed to stress after the pretreatment of PTX (0.05 or 0.1 µg) i.c.v. or i.t. once for 6 days. Blood glucose level was measured at 0, 30, 60 and 120 min after stress stimulation. The blood glucose level was increased in all stress groups. The blood glucose level reached at maximum level after 30 min of stress stimulation and returned to a normal level after 2 h of stress stimulation in restraint stress, physical, and emotional stress groups. The blood glucose level induced by cold-water swimming stress was gradually increased up to 1 h and returned to the normal level. The intracerebroventricular (i.c.v.) or intrathecal (i.t.) pretreatment with PTX, a Gi inhibitor, alone produced a hypoglycemia and almost abolished the elevation of the blood level induced by stress stimulation. The central pretreatment with PTX caused a reduction of plasma insulin level, whereas plasma corticosterone level was further up-regulated in all stress models. Our results suggest that the hyperglycemia produced by physical stress, emotional stress, restraint stress, and the cold-water swimming stress appear to be mediated by activation of centrally located PTX-sensitive G proteins. The reduction of blood glucose level by PTX appears to due to the reduction of plasma insulin level. The reduction of blood glucose level by PTX was accompanied by the reduction of plasma insulin level. Plasma corticosterone level up-regulation by PTX in stress models may be due to a blood glucose homeostatic mechanism.

Activation of AMPK by berberine induces hepatic lipid accumulation by upregulation of fatty acid translocase CD36 in mice

International Nuclear Information System (INIS)

Choi, You-Jin; Lee, Kang-Yo; Jung, Seung-Hwan; Kim, Hyung Sik; Shim, Gayong; Kim, Mi-Gyeong; Oh, Yu-Kyoung; Oh, Seon-Hee; Jun, Dae Won; Lee, Byung-Hoon

2017-01-01

Emerging evidence has shown that berberine has a protective effect against metabolic syndrome such as obesity and type II diabetes mellitus by activating AMP-activated protein kinase (AMPK). AMPK induces CD36 trafficking to the sarcolemma for fatty acid uptake and oxidation in contracting muscle. However, little is known about the effects of AMPK on CD36 regulation in the liver. We investigated whether AMPK activation by berberine affects CD36 expression and fatty acid uptake in hepatocytes and whether it is linked to hepatic lipid accumulation. Activation of AMPK by berberine or transduction with adenoviral vectors encoding constitutively active AMPK in HepG2 and mouse primary hepatocytes increased the expression and membrane translocation of CD36, resulting in enhanced fatty acid uptake and lipid accumulation as determined by BODIPY-C16 and Nile red fluorescence, respectively. Activation of AMPK by berberine induced the phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2) and subsequently induced CCAAT/enhancer-binding protein β (C/EBPβ) binding to the C/EBP-response element in the CD36 promoter in hepatocytes. In addition, hepatic CD36 expression and triglyceride levels were increased in normal diet-fed mice treated with berberine, but completely prevented when hepatic CD36 was silenced with adenovirus containing CD36-specific shRNA. Taken together, prolonged activation of AMPK by berberine increased CD36 expression in hepatocytes, resulting in fatty acid uptake via processes linked to hepatocellular lipid accumulation and fatty liver. - Highlights: • Berberine increases the expression and membrane translocation of CD36 in hepatocytes. • The increase of CD36 results in enhanced fatty acid uptake and lipid accumulation. • Berberine-induced fatty liver is mediated by AMPK-ERK-C/EBPβ pathway. • CD36-specific shRNA inhibited berberine-induced lipid accumulation in liver.

Activation of AMPK by berberine induces hepatic lipid accumulation by upregulation of fatty acid translocase CD36 in mice

Energy Technology Data Exchange (ETDEWEB)

Choi, You-Jin; Lee, Kang-Yo; Jung, Seung-Hwan [College of Pharmacy, Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, Hyung Sik [School of Pharmacy, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Shim, Gayong; Kim, Mi-Gyeong; Oh, Yu-Kyoung [College of Pharmacy, Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of); Oh, Seon-Hee [The Division of Natural Medical Sciences, College of Health Science, Chosun University, Gwangju 501-759 (Korea, Republic of); Jun, Dae Won [Internal Medicine, Hanyang University School of Medicine, Seoul 133-791 (Korea, Republic of); Lee, Byung-Hoon, E-mail: lee@snu.ac.kr [College of Pharmacy, Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of)

2017-02-01

Emerging evidence has shown that berberine has a protective effect against metabolic syndrome such as obesity and type II diabetes mellitus by activating AMP-activated protein kinase (AMPK). AMPK induces CD36 trafficking to the sarcolemma for fatty acid uptake and oxidation in contracting muscle. However, little is known about the effects of AMPK on CD36 regulation in the liver. We investigated whether AMPK activation by berberine affects CD36 expression and fatty acid uptake in hepatocytes and whether it is linked to hepatic lipid accumulation. Activation of AMPK by berberine or transduction with adenoviral vectors encoding constitutively active AMPK in HepG2 and mouse primary hepatocytes increased the expression and membrane translocation of CD36, resulting in enhanced fatty acid uptake and lipid accumulation as determined by BODIPY-C16 and Nile red fluorescence, respectively. Activation of AMPK by berberine induced the phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2) and subsequently induced CCAAT/enhancer-binding protein β (C/EBPβ) binding to the C/EBP-response element in the CD36 promoter in hepatocytes. In addition, hepatic CD36 expression and triglyceride levels were increased in normal diet-fed mice treated with berberine, but completely prevented when hepatic CD36 was silenced with adenovirus containing CD36-specific shRNA. Taken together, prolonged activation of AMPK by berberine increased CD36 expression in hepatocytes, resulting in fatty acid uptake via processes linked to hepatocellular lipid accumulation and fatty liver. - Highlights: • Berberine increases the expression and membrane translocation of CD36 in hepatocytes. • The increase of CD36 results in enhanced fatty acid uptake and lipid accumulation. • Berberine-induced fatty liver is mediated by AMPK-ERK-C/EBPβ pathway. • CD36-specific shRNA inhibited berberine-induced lipid accumulation in liver.

Botulinum toxin injection - larynx

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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; ...

Induction of diphtheria toxin-resistant mutants in human cells by ultraviolet light

International Nuclear Information System (INIS)

Rocchi, P.; Ferreri, A.M.; Capucci, A.; Prodi, G.

1981-01-01

Stable spontaneous mutants resistant to the protein synthesis inhibitor diphtheria toxin (DT) have been selected in human cell line EUE at a very low frequency (less than 8 x 10(-6)). U.v.-induced mutation has been quantitatively measured: treatment of cells with u.v. light increased the frequencies of diphtheria toxin resistant (DTr) mutants up to 1000-fold. The maximum recovery of DTr mutants was observed after a short expression period, for all u.v. doses tested, and was followed by a decrease in mutation frequency on subsequent passages

Induction of diphtheria toxin-resistant mutants in human cells by ultraviolet light

International Nuclear Information System (INIS)

Rocchi, P.; Ferreri, A.M.; Capucci, A.; Prodi, G.

1981-01-01

Stable spontaneous mutants resistant to the protein synthesis inhibitor diphtheria toxin (DT) have been selected in human cell line EUE at a very low frequency ( -6 ). U.v.-induced mutation has been quantitatively measured: treatment of cells with u.v. light increased the frequencies of diphtheria toxin resistant (DTsup(r)) mutants up to 1000-fold. The maximum recovery of DTsup(r) mutants was observed after a short expression period, for all u.v. doses tested, and was followed by a decrease in mutation frequency on subsequent passages. (author)

Citreoviridin induces triglyceride accumulation in hepatocytes through inhibiting PPAR-α in vivo and in vitro.

Science.gov (United States)

Feng, Chang; Li, Dandan; Jiang, Liping; Liu, Xiaofang; Li, Qiujuan; Geng, Chengyan; Sun, Xiance; Yang, Guang; Yao, Xiaofeng; Chen, Min

2017-08-01

Citreoviridin (CIT) is a mycotoxin produced by Penicillum citreonigrum, Aspergillus terreus and Eupenicillium ochrosalmoneum. CIT occurs naturally in moldy rice and corn. CIT is associated with the development of atherosclerosis in the general population. Alteration in hepatic lipid metabolism is a pathogenic factor in atherosclerosis. However the effect and the underlying mechanism of CIT on hepatic lipid metabolism are largely unknown. In this study, we reported that CIT induced triglyceride accumulation in mice liver and human liver HepG2 cells as shown in oil red O staining. CIT (0.1 mg/kg-0.3 mg/kg) for 6 weeks elevated liver triglyceride contents in mice. CIT inhibited the transactivation activity of peroxisome proliferator-activated receptor-α (PPAR-α) in hepatocyte in vivo and in vitro, as shown by the reduced mRNA levels of PPAR-α target genes which play key roles in lipid metabolism in various aspects. PPAR-α agonist fenofibrate attenuated CIT-induced triglyceride accumulation in HepG2 cells. Furthermore, CIT increased serum total cholesterol/high-density lipoprotein cholesterol ratio, a strong risk factor for cardiovascular disease. In summary, we reported that CIT induced PPAR-α-dependent hepatic triglyceride accumulation and dyslipidemia. Our data will provide new mechanistic insights into CIT-induced lipid alterations. Copyright © 2017 Elsevier B.V. All rights reserved.

[Intoxication of botulinum toxin].

Science.gov (United States)

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.

A High-Throughput, Precipitating Colorimetric Sandwich ELISA Microarray for Shiga Toxins

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Andrew Gehring

2014-06-01

Full Text Available Shiga toxins 1 and 2 (Stx1 and Stx2 from Shiga toxin-producing E. coli (STEC bacteria were simultaneously detected with a newly developed, high-throughput antibody microarray platform. The proteinaceous toxins were immobilized and sandwiched between biorecognition elements (monoclonal antibodies and pooled horseradish peroxidase (HRP-conjugated monoclonal antibodies. Following the reaction of HRP with the precipitating chromogenic substrate (metal enhanced 3,3-diaminobenzidine tetrahydrochloride or DAB, the formation of a colored product was quantitatively measured with an inexpensive flatbed page scanner. The colorimetric ELISA microarray was demonstrated to detect Stx1 and Stx2 at levels as low as ~4.5 ng/mL within ~2 h of total assay time with a narrow linear dynamic range of ~1–2 orders of magnitude and saturation levels well above background. Stx1 and/or Stx2 produced by various strains of STEC were also detected following the treatment of cultured cells with mitomycin C (a toxin-inducing antibiotic and/or B-PER (a cell-disrupting, protein extraction reagent. Semi-quantitative detection of Shiga toxins was demonstrated to be sporadic among various STEC strains following incubation with mitomycin C; however, further reaction with B-PER generally resulted in the detection of or increased detection of Stx1, relative to Stx2, produced by STECs inoculated into either axenic broth culture or culture broth containing ground beef.

Covalent structure of the insect toxin of the North African scorpion Androctonus australis Hector

International Nuclear Information System (INIS)

Darbon, H.; Kopeyan, C.; Rietschoten, J. van; Rochat, H.; Zlotkin, E.

1982-01-01

The complete covalent structure of the insect toxin purified from the venom of the North-African scorpion Androctonus australis Hector was described. Its amino acid sequence was established by phenylisothiocyanate degradation of several protein derivatives and proteolytic fragments in a liquid protein sequencer using either a ''protein'' or a ''peptide'' program. The position of the four disulfide bridges were deduced by analysis of proteolytic peptides before and after performic oxidation, and by partial labeling of the half cystine residues with [ 14 C]-iodoacetic acid and determining the specific radioactivities of the S-[ 14 C]-carboxymethylated phenylthiohydantoin cysteines. The sequences of the insect and mammal toxins from scorpions can be aligned with homology with the positions of seven half-cystine residues as registers. The mammal and insect toxins have three disulfide bridges at homologous positions. The fourth bridge is different in that Cys 12 in mammal toxin II is replaced by Cys 38 in the insect toxin. It is likely that the position of the disulfide bridges is the same for all scorpion neurotoxins active on mammals. We believe that the shift of one half-cystine residue in the insect toxin may induce a conformational change in the structure of the protein, which, in turn, may partially account for the total specificity of this toxin for insect nervous system. (author)

Acute myeloid leukemia-targeted toxin activates both apoptotic and necroptotic death mechanisms.

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Henrick Horita

Full Text Available BACKGROUND: Acute myelogenous leukemia (AML is the second most common leukemia with approximately 13,410 new cases and 8,990 deaths annually in the United States. A novel fusion toxin treatment, diphtheria toxin GM-CSF (DT-GMCSF has been shown to selectively eliminate leukemic repopulating cells that are critical for the formation of AML. We previously showed that DT-GMCSF treatment of U937 cells, an AML cell line, causes activation of caspases and the induction of apoptosis. METHODS AND FINDINGS: In this study we further investigate the mechanisms of cell death induced by DT-GMCSF and show that, in addition to the activation of caspase-dependent apoptosis, DT-GMCSF also kills AML cells by simultaneously activating caspase-independent necroptosis. These mechanisms depend on the ability of the targeted toxin to inhibit protein synthesis, and are not affected by the receptor that is targeted or the mechanism through which protein synthesis is blocked. CONCLUSIONS: We conclude that fusion toxin proteins may be effective for treating AML cells whether or not they are defective in apoptosis.

Why do we study animal toxins?

Science.gov (United States)

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

Staphylococcus aureus α-Toxin Induces Actin Filament Remodeling in Human Airway Epithelial Model Cells.

Science.gov (United States)

Ziesemer, Sabine; Eiffler, Ina; Schönberg, Alfrun; Müller, Christian; Hochgräfe, Falko; Beule, Achim G; Hildebrandt, Jan-Peter

2018-04-01

Exposure of cultured human airway epithelial model cells (16HBE14o-, S9) to Staphylococcus aureus α-toxin (hemolysin A, Hla) induces changes in cell morphology and cell layer integrity that are due to the inability of the cells to maintain stable cell-cell or focal contacts and to properly organize their actin cytoskeletons. The aim of this study was to identify Hla-activated signaling pathways involved in regulating the phosphorylation level of the actin-depolymerizing factor cofilin. We used recombinant wild-type hemolysin A (rHla) and a variant of Hla (rHla-H35L) that is unable to form functional transmembrane pores to treat immortalized human airway epithelial cells (16HBE14o-, S9) as well as freshly isolated human nasal tissue. Our results indicate that rHla-mediated changes in cofilin phosphorylation require the formation of functional Hla pores in the host cell membrane. Formation of functional transmembrane pores induced hypophosphorylation of cofilin at Ser3, which was mediated by rHla-induced attenuation of p21-activated protein kinase and LIM kinase activities. Because dephosphorylation of pSer3-cofilin results in activation of this actin-depolymerizing factor, treatment of cells with rHla resulted in loss of actin stress fibers from the cells and destabilization of cell shape followed by the appearance of paracellular gaps in the cell layers. Activation of protein kinase A or activation of small GTPases (Rho, Rac, Cdc42) do not seem to be involved in this response.

Investigation of inactivation of Clostridium botulinum toxin by nuclear radiation

International Nuclear Information System (INIS)

Kaltenhaeuser, A.; Werner, K.H.

1989-01-01

The effect of nuclear radiation on the toxicity and the molecular structure of the toxin produced by the microorganism Clostridium botulinum type A was investigated. The radiation induced changes in the structure of the toxin molecule. This effect is influenced by the composition or the medium above the toxin solution as well as by the temperature during the irradiation. The results of the investigation indicate that with increasing irradiation dose a new molecule was formed with immunological properties similar to the properties of the original molecule however with a greater molecular weight. After exposure to a radiation dose of 3,4 Mrad at normal temperature in air, complete detoxification of the substance was found. Immunizing experiments with the toxoid with two guinea-pigs indicated a pronounced increase of the antibody titer in the serum after 4 weeks. Vaccination experiments with the toxoid on animals show, that the protection against the effect of the toxin corresponds to the demands of the European Pharmacopoeia. The efficiency of the toxoid shows a similar efficiency as toxoids produced by chemical methods. The production of a toxoid-viccine with the relatively simple method of nuclear radiation appears possible. (orig./MG) With 12 refs., 3 tabs., 11 figs [de

A Constitutive Model for Flow-Induced Anisotropic Behavior of Viscoelastic Complex Fluids

International Nuclear Information System (INIS)

Zhu, H.; De Kee, D.

2008-01-01

Flow-induced structural anisotropy could result when a complex fluid system is removed from equilibrium by means of hydrodynamic forces. In this paper, a general theory is developed to model flow induced anisotropic behavior of complex viscoelastic systems, e.g. polymer solutions/melts and suspensions. The rheological properties are characterized by viscosity and relaxation time tensors. We consider a second-rank tensor as a measure of the microstructure. We consider the effect of the flow on the structural changes: i.e. the evolution of the microstructure tensor is governed by a relaxation-type differential equation. We also propose that the viscosity and the relaxation time tensors depend on the second-rank microstructure tensor. That is as the microstructure tensor changes with the applied rate of deformation, the viscosity and relaxation time tensors evolve accordingly. As an example we consider elongational flow of two complex fluids

Seismic and aseismic fault slip in response to fluid injection observed during field experiments at meter scale

Science.gov (United States)

Cappa, F.; Guglielmi, Y.; De Barros, L.; Wynants-Morel, N.; Duboeuf, L.

2017-12-01

During fluid injection, the observations of an enlarging cloud of seismicity are generally explained by a direct response to the pore pressure diffusion in a permeable fractured rock. However, fluid injection can also induce large aseismic deformations which provide an alternative mechanism for triggering and driving seismicity. Despite the importance of these two mechanisms during fluid injection, there are few studies on the effects of fluid pressure on the partitioning between seismic and aseismic motions under controlled field experiments. Here, we describe in-situ meter-scale experiments measuring synchronously the fluid pressure, the fault motions and the seismicity directly in a fault zone stimulated by controlled fluid injection at 280 m depth in carbonate rocks. The experiments were conducted in a gallery of an underground laboratory in south of France (LSBB, http://lsbb.eu). Thanks to the proximal monitoring at high-frequency, our data show that the fluid overpressure mainly induces a dilatant aseismic slip (several tens of microns up to a millimeter) at the injection. A sparse seismicity (-4 laws, we simulated an experiment and investigated the relative contribution of the fluid pressure diffusion and stress transfer on the seismic and aseismic fault behavior. The model reproduces the hydromechanical data measured at injection, and show that the aseismic slip induced by fluid injection propagates outside the pressurized zone where accumulated shear stress develops, and potentially triggers seismicity. Our models also show that the permeability enhancement and friction evolution are essential to explain the fault slip behavior. Our experimental results are consistent with large-scale observations of fault motions at geothermal sites (Wei et al., 2015; Cornet, 2016), and suggest that controlled field experiments at meter-scale are important for better assessing the role of fluid pressure in natural and human-induced earthquakes.

The mitochondrial toxin, 3-nitropropionic acid, induces extracellular Zn2+ accumulation in rat hippocampus slices.

Science.gov (United States)

Wei, Guo; Hough, Christopher J; Sarvey, John M

2004-11-11

3-nitropropionic acid (3-NPA), a suicide inhibitor of succinate dehydrogenase (SDH; complex II), has been used to provide useful experimental models of Huntington's disease (HD) and "chemical hypoxia" in rodents. The trace ion Zn2+ has been shown to cause neurodegeneration. Employing real-time Newport Green fluorescence imaging of extracellular Zn2+, we found that 3-NPA (10-100 microM) caused a concentration-dependent increase in the concentration of extracellular Zn2+ ([Zn2+]o) in acute rat hippocampus slices. This increase in [Zn2+]o was abolished by 10 mM CaEDTA. The increase of [Zn2+]o was also accompanied by a rapid increase of cytoplasmic-free Zn2+ concentration ([Zn2+]i). The induction of Zn2+ release by 3-MPA in hippocampus slices points to a potential mechanism by which 3-NPA might induce neurodegeneration.

ATP Release from Human Airway Epithelial Cells Exposed to Staphylococcus aureus Alpha-Toxin

Directory of Open Access Journals (Sweden)

Romina Baaske

2016-12-01

Full Text Available Airway epithelial cells reduce cytosolic ATP content in response to treatment with S. aureus alpha-toxin (hemolysin A, Hla. This study was undertaken to investigate whether this is due to attenuated ATP generation or to release of ATP from the cytosol and extracellular ATP degradation by ecto-enzymes. Exposure of cells to rHla did result in mitochondrial calcium uptake and a moderate decline in mitochondrial membrane potential, indicating that ATP regeneration may have been attenuated. In addition, ATP may have left the cells through transmembrane pores formed by the toxin or through endogenous release channels (e.g., pannexins activated by cellular stress imposed on the cells by toxin exposure. Exposure of cells to an alpha-toxin mutant (H35L, which attaches to the host cell membrane but does not form transmembrane pores, did not induce ATP release from the cells. The Hla-mediated ATP-release was completely blocked by IB201, a cyclodextrin-inhibitor of the alpha-toxin pore, but was not at all affected by inhibitors of pannexin channels. These results indicate that, while exposure of cells to rHla may somewhat reduce ATP production and cellular ATP content, a portion of the remaining ATP is released to the extracellular space and degraded by ecto-enzymes. The release of ATP from the cells may occur directly through the transmembrane pores formed by alpha-toxin.

Requirement of Hsp105 in CoCl{sub 2}-induced HIF-1α accumulation and transcriptional activation

Energy Technology Data Exchange (ETDEWEB)

Mikami, Hiroki; Saito, Youhei, E-mail: ysaito@mb.kyoto-phu.ac.jp; Okamoto, Namiko; Kakihana, Ayana; Kuga, Takahisa; Nakayama, Yuji, E-mail: nakayama@mb.kyoto-phu.ac.jp

2017-03-15

The mammalian stress protein Hsp105α protects cells from stress conditions. Several studies have indicated that Hsp105α is overexpressed in many types of solid tumors, which contain hypoxic microenvironments. However, the role of Hsp105α in hypoxic tumors remains largely unknown. We herein demonstrated the involvement of Hsp105α in HIF-1 functions induced by the hypoxia-mimetic agent CoCl{sub 2}. While Hsp105α is mainly localized in the cytoplasm under normal conditions, a treatment with CoCl{sub 2} induces the nuclear localization of Hsp105α, which correlated with HIF-1α expression levels. The overexpression of degradation-resistant HIF-1α enhances the nuclear localization of Hsp105α without the CoCl{sub 2} treatment. The CoCl{sub 2}-dependent transcriptional activation of HIF-1, which is measured using a reporter gene containing a HIF-responsive element, is reduced by the knockdown of Hsp105α. Furthermore, the CoCl{sub 2}-induced accumulation of HIF-1α is enhanced by heat shock, which results in the nuclear localization of Hsp105, and is suppressed by the knockdown of Hsp105. Hsp105 associates with HIF-1α in CoCl{sub 2}-treated cells. These results suggest that Hsp105α plays an important role in the functions of HIF-1 under hypoxic conditions, in which Hsp105α enhances the accumulation and transcriptional activity of HIF-1 through the HIF-1α-mediated nuclear localization of Hsp105α. - Highlights: • Hsp105α is required for the CoCl{sub 2}-induced transcriptional activation and accumulation of HIF-1. • Hsp105α localizes to the nucleus and interacts with HIF-1α in CoCl{sub 2}-treated cells. • Hsp105 enhances the CoCl{sub 2}-induced accumulation of HIF-1α under heat shock conditions.

Genetic fusions of a CFA/I/II/IV MEFA (multiepitope fusion antigen) and a toxoid fusion of heat-stable toxin (STa) and heat-labile toxin (LT) of enterotoxigenic Escherichia coli (ETEC) retain broad anti-CFA and antitoxin antigenicity.

Science.gov (United States)

Ruan, Xiaosai; Sack, David A; Zhang, Weiping

2015-01-01

Immunological heterogeneity has long been the major challenge in developing broadly effective vaccines to protect humans and animals against bacterial and viral infections. Enterotoxigenic Escherichia coli (ETEC) strains, the leading bacterial cause of diarrhea in humans, express at least 23 immunologically different colonization factor antigens (CFAs) and two distinct enterotoxins [heat-labile toxin (LT) and heat-stable toxin type Ib (STa or hSTa)]. ETEC strains expressing any one or two CFAs and either toxin cause diarrhea, therefore vaccines inducing broad immunity against a majority of CFAs, if not all, and both toxins are expected to be effective against ETEC. In this study, we applied the multiepitope fusion antigen (MEFA) strategy to construct ETEC antigens and examined antigens for broad anti-CFA and antitoxin immunogenicity. CFA MEFA CFA/I/II/IV [CVI 2014, 21(2):243-9], which carried epitopes of seven CFAs [CFA/I, CFA/II (CS1, CS2, CS3), CFA/IV (CS4, CS5, CS6)] expressed by the most prevalent and virulent ETEC strains, was genetically fused to LT-STa toxoid fusion monomer 3xSTaA14Q-dmLT or 3xSTaN12S-dmLT [IAI 2014, 82(5):1823-32] for CFA/I/II/IV-STaA14Q-dmLT and CFA/I/II/IV-STaN12S-dmLT MEFAs. Mice intraperitoneally immunized with either CFA/I/II/IV-STa-toxoid-dmLT MEFA developed antibodies specific to seven CFAs and both toxins, at levels equivalent or comparable to those induced from co-administration of the CFA/I/II/IV MEFA and toxoid fusion 3xSTaN12S-dmLT. Moreover, induced antibodies showed in vitro adherence inhibition activities against ETEC or E. coli strains expressing these seven CFAs and neutralization activities against both toxins. These results indicated CFA/I/II/IV-STa-toxoid-dmLT MEFA or CFA/I/II/IV MEFA combined with 3xSTaN12S-dmLT induced broadly protective anti-CFA and antitoxin immunity, and suggested their potential application in broadly effective ETEC vaccine development. This MEFA strategy may be generally used in multivalent

Genetic fusions of a CFA/I/II/IV MEFA (multiepitope fusion antigen and a toxoid fusion of heat-stable toxin (STa and heat-labile toxin (LT of enterotoxigenic Escherichia coli (ETEC retain broad anti-CFA and antitoxin antigenicity.

Directory of Open Access Journals (Sweden)

Xiaosai Ruan

Full Text Available Immunological heterogeneity has long been the major challenge in developing broadly effective vaccines to protect humans and animals against bacterial and viral infections. Enterotoxigenic Escherichia coli (ETEC strains, the leading bacterial cause of diarrhea in humans, express at least 23 immunologically different colonization factor antigens (CFAs and two distinct enterotoxins [heat-labile toxin (LT and heat-stable toxin type Ib (STa or hSTa]. ETEC strains expressing any one or two CFAs and either toxin cause diarrhea, therefore vaccines inducing broad immunity against a majority of CFAs, if not all, and both toxins are expected to be effective against ETEC. In this study, we applied the multiepitope fusion antigen (MEFA strategy to construct ETEC antigens and examined antigens for broad anti-CFA and antitoxin immunogenicity. CFA MEFA CFA/I/II/IV [CVI 2014, 21(2:243-9], which carried epitopes of seven CFAs [CFA/I, CFA/II (CS1, CS2, CS3, CFA/IV (CS4, CS5, CS6] expressed by the most prevalent and virulent ETEC strains, was genetically fused to LT-STa toxoid fusion monomer 3xSTaA14Q-dmLT or 3xSTaN12S-dmLT [IAI 2014, 82(5:1823-32] for CFA/I/II/IV-STaA14Q-dmLT and CFA/I/II/IV-STaN12S-dmLT MEFAs. Mice intraperitoneally immunized with either CFA/I/II/IV-STa-toxoid-dmLT MEFA developed antibodies specific to seven CFAs and both toxins, at levels equivalent or comparable to those induced from co-administration of the CFA/I/II/IV MEFA and toxoid fusion 3xSTaN12S-dmLT. Moreover, induced antibodies showed in vitro adherence inhibition activities against ETEC or E. coli strains expressing these seven CFAs and neutralization activities against both toxins. These results indicated CFA/I/II/IV-STa-toxoid-dmLT MEFA or CFA/I/II/IV MEFA combined with 3xSTaN12S-dmLT induced broadly protective anti-CFA and antitoxin immunity, and suggested their potential application in broadly effective ETEC vaccine development. This MEFA strategy may be generally used in

Temperature induced effects on the durability of MR fluids

International Nuclear Information System (INIS)

Wiehe, A; Maas, J; Kieburg, C

2013-01-01

Although commercial MR fluids exist for quite some time now and the feasibility as well as the advantages of the MR technology have been demonstrated for several applications by a variety of MR actuator prototypes, a sustainable market break-through of brake and clutch applications utilizing the shear mode is still missing. Essential impediments are the marginal knowledge about the durability of the MR technology. To overcome this situation, a long-term measurement system was developed for the durability analysis of MR fluid formulations within a technical relevant scale with respect to the volume of MR fluid and the transmitted torque. The focus of the presented series of measurements is given to the analysis of temperature induced effects on the durability. In this context four different failure indicators can be distinguished, namely an apparent negative viscosity, deviations in torque data obtained from different measurements as well as a pressure increase and a drop in the on-state torque. The measurement data of the present durability experiments indicate a significant dependency of the attainable energy intake density on the temperature. The aim of such durability tests is to establish a reliable data base for the industry to estimate the life-time of MR devices.

Induction of rapid and selective cell necrosis in Drosophila using Bacillus thuringiensis Cry toxin and its silkworm receptor.

Science.gov (United States)

Obata, Fumiaki; Tanaka, Shiho; Kashio, Soshiro; Tsujimura, Hidenobu; Sato, Ryoichi; Miura, Masayuki

2015-07-08

Genetic ablation of target cells is a powerful tool to study the origins and functions of cells, tissue regeneration, or pathophysiology in a human disease model in vivo. Several methods for selective cell ablation by inducing apoptosis have been established, using exogenous toxins or endogenous proapoptotic genes. However, their application is limited to cells with intact apoptotic machinery. Herein, we established a method for inducing rapid and selective cell necrosis by the pore-forming bacterial toxin Cry1Aa, which is specifically active in cells expressing the Cry1Aa receptor (CryR) derived from the silkworm Bombyx mori. We demonstrated that overexpressing CryR in Drosophila melanogaster tissues induced rapid cell death of CryR-expressing cells only, in the presence of Cry1Aa toxin. Cry/CryR system was effective against both proliferating cells in imaginal discs and polyploid postmitotic cells in the fat body. Live imaging analysis of cell ablation revealed swelling and subsequent osmotic lysis of CryR-positive cells after 30 min of incubation with Cry1Aa toxin. Osmotic cell lysis was still triggered when apoptosis, JNK activation, or autophagy was inhibited, suggesting that Cry1Aa-induced necrotic cell death occurred independently of these cellular signaling pathways. Injection of Cry1Aa into the body cavity resulted in specific ablation of CryR-expressing cells, indicating the usefulness of this method for in vivo cell ablation. With Cry toxins from Bacillus thuringiensis, we developed a novel method for genetic induction of cell necrosis. Our system provides a "proteinous drill" for killing target cells through physical injury of the cell membrane, which can potentially be used to ablate any cell type in any organisms, even those that are resistant to apoptosis or JNK-dependent programmed cell death.

Thermal-Induced Non-linearity of Ag Nano-fluid Prepared using γ-Radiation Method

International Nuclear Information System (INIS)

Esmaeil Shahriari; Wan Mahmood Mat Yunus; Zainal Abidin Talib; Elias Saion

2011-01-01

The non-linear refractive index of Ag nano-fluids prepared by γ-radiation method was investigated using a single beam z-scan technique. Under CW 532 nm laser excitation with power output of 40 mW, the Ag nano-fluids showed a large thermal-induced non-linear refractive index. In the present work it was determined that the non-linear refractive index for Ag nano-fluids is -4.80x10 -8 cm 2 / W. The value of Δn 0 was calculated to be -2.05x10 -4 . Our measurements also confirmed that the non-linear phenomenon was caused by the self-defocusing process making them good candidates for non linear optical devices. (author)

[Botulinum toxin and rejuvenation of the eye].

Science.gov (United States)

Volpei, Ch; Miniconi, M-J; Brunner, C I; Besins, T; Braccini, F

2013-01-01

Treatments with botulinum toxin in the forehead and periorbital areas may induce disappointing or even paradoxical results. Our study, focused on this area aimed at refining injection techniques by analyzing muscular balances and comparing the effect according to injection doses and topography. This experimental study has been carried out in the form of 2 session workshops, with volunteers duly informed of the study contents and giving their informed consent. It was conducted by physicians and surgeons members of SAMCEP* (Société Avancée de Médecine et Chirurgie Esthétique et Plastique). The botulinum toxin was onabotulinumtoxin A. Results were evaluated 15 days after treatment, in regard to global eyebrow position, eyebrow head and tail position; muscle interactions; lines above the eyebrow. Eleven case reports and their results are shown and discussed. Our study underlines two important insights: muscle balances and "border areas", between orbicularis oculi and corrugator, key features for eyebrow head, and between frontalis and orbicularis oculifor eyebrow tail.

JBP485 improves gentamicin-induced acute renal failure by regulating the expression and function of Oat1 and Oat3 in rats

Energy Technology Data Exchange (ETDEWEB)

Guo, Xinjin [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, Dalian (China); Meng, Qiang; Liu, Qi; Wang, Changyuan; Sun, Huijun; Peng, Jinyong; Ma, Xiaochi [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, Dalian (China); Provincial Key Laboratory for Pharmacokinetics and Transport, Dalian Medical University, Liaoning (China); Kaku, Taiichi [Japan Bioproducts Industry Co. Ltd., Tomigaya, Shibuya-ku, Tokyo (Japan); Liu, Kexin, E-mail: kexinliu@dlmedu.edu.cn [Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, Dalian (China); Provincial Key Laboratory for Pharmacokinetics and Transport, Dalian Medical University, Liaoning (China)

2013-09-01

We investigated the effects of JBP485 (an anti-inflammatory dipeptide and a substrate of OAT) on regulation of the expression and function of renal Oat1 and Oat3, which can accelerate the excretion of accumulated uremic toxins (e.g. indoxyl sulfate) in the kidney to improve gentamicin-induced ARF in rats. JBP485 caused a significant decrease in the accumulation of endogenous substances (creatinine, blood urea nitrogen and indoxyl sulfate) in vivo, an increase in the excretion of exogenous compounds (lisinopril and inulin) into urine, and up-regulation of the expressions of renal Oat1 and Oat3 in the kidney tissues and slices via substrate induction. To determine the effect of JBP485 on the accelerated excretion of uremic toxins mediated by Oat1 and Oat3, the mRNA and protein expression levels of renal basolateral Oats were assessed by quantitative real-time PCR, western blot, immunohistochemical analysis and an immunofluorescence method. Gentamicin down-regulated the expression of Oats mRNA and protein in rat kidney, and these effects were reversed after administration of JBP485. In addition, JBP485 caused a significant decrease in MPO and MDA levels in the kidney, and improved the pathological condition of rat kidney. These results indicated that JBP485 improved acute renal failure by increasing the expression and function of Oat1 and Oat3, and by decreasing overoxidation of the kidney in gentamicin-induced ARF rats. - Highlights: • JBP485 could up-regulate function and expression of Oat1 and Oat3 in kidney. • Effects of JBP485 on ARF are mediated by stimulating excretion of uremic toxins. • JBP485 protected against gentamicin-induced ARF by decreasing MPO and MDA.

Plasmodium falciparum: characterization of toxin-associated proteins and identification of a hemoglobin containing parasite cytokine stimulator

DEFF Research Database (Denmark)

Kristensen, G; Jakobsen, P H

1996-01-01

]-methionine and immunoprecipitated the labeled antigens with an antiserum against IMP which blocks malaria parasite-induced TNF production. We detected four proteins associated with IMP when the immunoprecipitates were separated by SDS-PAGE and analyzed by autoradiography. To evaluate the capacity of different P. falciparum......Previous studies have indicated the inositol monophosphate (IMP) is a component of the malaria parasite toxin that induces cytokines such as tumour necrosis factor (TNF). To further characterize the toxin we have labeled Plasmodium falciparum in vitro cultures with [14C]inositol or [35S...

Defense against Toxin Weapons

National Research Council Canada - National Science Library

Franz, David

1998-01-01

.... We typically fear what we do not understand. Although un- derstanding toxin poisoning is less useful in a toxin attack than knowledge of cold injury on an Arctic battlefield, information on any threat reduces its potential to harm...

Oxidative stress induction by T-2 toxin causes DNA damage and triggers apoptosis via caspase pathway in human cervical cancer cells

International Nuclear Information System (INIS)

Chaudhari, Manjari; Jayaraj, R.; Bhaskar, A.S.B.; Lakshmana Rao, P.V.

2009-01-01

T-2 toxin is the most toxic trichothecene and both humans and animals suffer from several pathological conditions after consumption of foodstuffs contaminated with trichothecenes. We investigated the molecular mechanism of T-2 toxin induced cytotoxicity and cell death in HeLa cells. T-2 toxin at LC50 of 10 ng/ml caused time dependent increase in cytotoxicity as assessed by dye uptake, lactatedehydrogenase leakage and MTT assay. The toxin caused generation of reactive oxygen species as early as 30 min followed by significant depletion of glutathione levels and increased lipid peroxidation. The results indicate oxidative stress as underlying mechanism of cytotoxicity. Single stranded DNA damage after T-2 treatment was observed as early as 2 and 4 h by DNA diffusion assay. The cells exhibited apoptotic morphology like condensed chromatin and nuclear fragmentation after 4 h of treatment. Downstream of T-2 induced oxidative stress and DNA damage a time dependent increase in expression level of p53 protein was observed. The increase in Bax/Bcl2 ratio indicated shift in response, in favour of apoptotic process in T-2 toxin treated cells. Western blot analysis showed increase in levels of mitochondrial apoptogenic factors Bax, Bcl-2, cytochrome-c followed by activation of caspases-9, -3 and -7 leading to DNA fragmentation and apoptosis. In addition to caspase-dependent pathway, our results showed involvement of caspase-independent AIF pathway in T-2 induced apoptosis. Broad spectrum caspase inhibitor z-VAD-fmk could partially protect the cells from DNA damage but could not inhibit AIF induced oligonucleosomal DNA fragmentation beyond 4 h. Results of the study clearly show that oxidative stress is the underlying mechanism by which T-2 toxin causes DNA damage and apoptosis.

Food toxin detection with atomic force microscope

Science.gov (United States)

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...

Kalium: a database of potassium channel toxins from scorpion venom.

Science.gov (United States)

Kuzmenkov, Alexey I; Krylov, Nikolay A; Chugunov, Anton O; Grishin, Eugene V; Vassilevski, Alexander A

2016-01-01

Kalium (http://kaliumdb.org/) is a manually curated database that accumulates data on potassium channel toxins purified from scorpion venom (KTx). This database is an open-access resource, and provides easy access to pages of other databases of interest, such as UniProt, PDB, NCBI Taxonomy Browser, and PubMed. General achievements of Kalium are a strict and easy regulation of KTx classification based on the unified nomenclature supported by researchers in the field, removal of peptides with partial sequence and entries supported by transcriptomic information only, classification of β-family toxins, and addition of a novel λ-family. Molecules presented in the database can be processed by the Clustal Omega server using a one-click option. Molecular masses of mature peptides are calculated and available activity data are compiled for all KTx. We believe that Kalium is not only of high interest to professional toxinologists, but also of general utility to the scientific community.Database URL:http://kaliumdb.org/. © The Author(s) 2016. Published by Oxford University Press.

Conditional Toxin Splicing Using a Split Intein System.

Science.gov (United States)

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

International Nuclear Information System (INIS)

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

1987-01-01

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 μg/ml. 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 4 Cl. The infections of GE1 cells and the parent cells by vesicular stomatitis virus were similar. GE1 cells 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

A Polychaete's powerful punch: venom gland transcriptomics of Glycera reveals a complex cocktail of toxin homologs.

Science.gov (United States)

von Reumont, Björn M; Campbell, Lahcen I; Richter, Sandy; Hering, Lars; Sykes, Dan; Hetmank, Jörg; Jenner, Ronald A; Bleidorn, Christoph

2014-09-05

Glycerids are marine annelids commonly known as bloodworms. Bloodworms have an eversible proboscis adorned with jaws connected to venom glands. Bloodworms prey on invertebrates, and it is known that the venom glands produce compounds that can induce toxic effects in animals. Yet, none of these putative toxins has been characterized on a molecular basis. Here we present the transcriptomic profiles of the venom glands of three species of bloodworm, Glycera dibranchiata, Glycera fallax and Glycera tridactyla, as well as the body tissue of G. tridactyla. The venom glands express a complex mixture of transcripts coding for putative toxin precursors. These transcripts represent 20 known toxin classes that have been convergently recruited into animal venoms, as well as transcripts potentially coding for Glycera-specific toxins. The toxins represent five functional categories: Pore-forming and membrane-disrupting toxins, neurotoxins, protease inhibitors, other enzymes, and CAP domain toxins. Many of the transcripts coding for putative Glycera toxins belong to classes that have been widely recruited into venoms, but some are homologs of toxins previously only known from the venoms of scorpaeniform fish and monotremes (stonustoxin-like toxin), turrid gastropods (turripeptide-like peptides), and sea anemones (gigantoxin I-like neurotoxin). This complex mixture of toxin homologs suggests that bloodworms employ venom while predating on macroscopic prey, casting doubt on the previously widespread opinion that G. dibranchiata is a detritivore. Our results further show that researchers should be aware that different assembly methods, as well as different methods of homology prediction, can influence the transcriptomic profiling of venom glands. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Simulation of dynamic magnetic particle capture and accumulation around a ferromagnetic wire

Energy Technology Data Exchange (ETDEWEB)

Choomphon-anomakhun, Natthaphon [Department of Physics, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330 (Thailand); Ebner, Armin D. [Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Natenapit, Mayuree [Department of Physics, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330 (Thailand); Ritter, James A. [Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

2017-04-15

A new approach for modeling high gradient magnetic separation (HGMS)-type systems during the time-dependent capture and accumulation of magnetic particles by a ferromagnetic wire was developed. This new approach assumes the fluid (slurry) viscosity, comprised of water and magnetic particles, is a function of the magnetic particle concentration in the fluid, with imposed maxima on both the particle concentration and fluid viscosity to avoid unrealistic limits. In 2-D, the unsteady-state Navier-Stokes equations for compressible fluid flow and the unsteady-state continuity equations applied separately to the water and magnetic particle phases in the slurry were solved simultaneously, along with the Laplace equations for the magnetic potential applied separately to the slurry and wire, to evaluate the velocities and concentrations around the wire in a narrow channel using COMSOL Multiphysics. The results from this model revealed very realistic magnetically attractive and repulsive zones forming in time around the wire. These collection zones formed their own impermeable viscous phase during accumulation that was also magnetic with its area and magnetism impacting locally both the fluid flow and magnetic fields around the wire. These collection zones increased with an increase in the applied magnetic field. For a given set of conditions, the capture ability peaked and then decreased to zero at infinite time during magnetic particle accumulation in the collection zones. Predictions of the collection efficiency from a steady-state, clean collector, trajectory model could not show this behavior; it also agreed only qualitatively with the dynamic model and then only at the early stages of collection and more so at a higher applied magnetic field. Also, the collection zones decreased in size when the accumulation regions included magnetic particle magnetization (realistic) compared to when they excluded it (unrealistic). Overall, this might be the first time a mathematical

The apoptogenic toxin AIP56 is a metalloprotease A-B toxin that cleaves NF-κb P65.

Directory of Open Access Journals (Sweden)

Daniela S Silva

2013-02-01

Full Text Available AIP56 (apoptosis-inducing protein of 56 kDa is a major virulence factor of Photobacterium damselae piscicida (Phdp, a Gram-negative pathogen that causes septicemic infections, which are among the most threatening diseases in mariculture. The toxin triggers apoptosis of host macrophages and neutrophils through a process that, in vivo, culminates with secondary necrosis of the apoptotic cells contributing to the necrotic lesions observed in the diseased animals. Here, we show that AIP56 is a NF-κB p65-cleaving zinc-metalloprotease whose catalytic activity is required for the apoptogenic effect. Most of the bacterial effectors known to target NF-κB are type III secreted effectors. In contrast, we demonstrate that AIP56 is an A-B toxin capable of acting at distance, without requiring contact of the bacteria with the target cell. We also show that the N-terminal domain cleaves NF-κB at the Cys(39-Glu(40 peptide bond and that the C-terminal domain is involved in binding and internalization into the cytosol.

Computational Studies of Snake Venom Toxins.

Science.gov (United States)

Ojeda, Paola G; Ramírez, David; Alzate-Morales, Jans; Caballero, Julio; Kaas, Quentin; González, Wendy

2017-12-22

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.

Computational Studies of Snake Venom Toxins

Directory of Open Access Journals (Sweden)

Paola G. Ojeda

2017-12-01

Full Text Available 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.

Cholera toxin B subunit-binding and ganglioside GM1 immuno-expression are not necessarily correlated in human salivary glands

DEFF Research Database (Denmark)

Kirkeby, Svend

2014-01-01

human submandibular, parotid and palatinal glands using cholera toxin sub-unit B and two polyclonal antibodies against ganglioside GM1 as biomarkers. RESULTS: Immunofluorescence microscopy showed that the toxin and antibodies were co-localized in some acini but not in others. The cholera toxin mainly...... reacted with the cell membranes of the mucous acini in the submandibular gland, while incubation with the antibody against GM1 gave rise to a staining of the cytoplasm. The cytoplasm in some secretory acinar cells in the parotid gland was stained by the cholera toxin, whereas only small spots...... on the plasma membranes reacted with anti-GM1. The plasma membranes in the parotid excretory ducts appeared to react to anti-GM1, but not to cholera toxin. CONCLUSIONS: Cholera toxin induces the expression of ion channels and carriers in the small intestine and increases the production of secretory mucins...

Mitogen-activated protein kinase kinase kinase (MAPKKK) 4 from rapeseed (Brassica napus L.) is a novel member inducing ROS accumulation and cell death

Energy Technology Data Exchange (ETDEWEB)

Li, Liang, E-mail: 18710470987@163.com; Ye, Chaofei, E-mail: yechaofei001@163.com; Zhao, Rui, E-mail: 571828628@qq.com; Li, Xin, E-mail: 1458272138@qq.com; Liu, Wu-zhen, E-mail: happywuzhenliu@163.com; Wu, Feifei, E-mail: 283915941@qq.com; Yan, Jingli, E-mail: yanjingli512@163.com; Jiang, Yuan-Qing, E-mail: jiangyq@nwafu.edu.cn; Yang, Bo, E-mail: yangwl@nwafu.edu.cn

2015-11-27

MAPKKK is the largest family of MAPK cascade, which is known to play important roles in plant growth, development and immune responses. So far, only a few have been functionally characterized even in the model plant, Arabidopsis due to the potential functional redundancy of MAPKKK. We previously identified and cloned a few MAPKKK family genes from rapeseed. In this study, BnaMAPKKK4 was characterized as a member in eliciting accumulation of reactive oxygen species (ROS) and hypersensitive response (HR)-like cell death. This is accompanied with accumulation of malondialdehyde (MDA), anthocyanin as well as nuclear DNA fragmentation. The transcript abundance of a series of ROS accumulation, cell death, and defense response related genes were up-regulated by the expression of MAPKKK4. Further investigation identified BnaMAPKKK4 elicited ROS through the downstream MPK3. These results indicate that BnaMAPKKK4 and its downstream components function in the ROS-induced cell death. - Highlights: • Expression of rapeseed MAPKKK4 induced ROS accumulation and cell death in leaves. • Cell death induced by MAPKKK4 is associated with membrane lipid peroxidation and DNA fragmentation. • MAPKKK4 interacts with MKK5 and MPK3. • MAPKKK4-induced ROS accumulation and cell death require downstream WIPK and SIPK. • MAPKKK4 is a novel MAPKKK modulating ROS accumulation and cell death.

Mitogen-activated protein kinase kinase kinase (MAPKKK) 4 from rapeseed (Brassica napus L.) is a novel member inducing ROS accumulation and cell death

International Nuclear Information System (INIS)

Li, Liang; Ye, Chaofei; Zhao, Rui; Li, Xin; Liu, Wu-zhen; Wu, Feifei; Yan, Jingli; Jiang, Yuan-Qing; Yang, Bo

2015-01-01

MAPKKK is the largest family of MAPK cascade, which is known to play important roles in plant growth, development and immune responses. So far, only a few have been functionally characterized even in the model plant, Arabidopsis due to the potential functional redundancy of MAPKKK. We previously identified and cloned a few MAPKKK family genes from rapeseed. In this study, BnaMAPKKK4 was characterized as a member in eliciting accumulation of reactive oxygen species (ROS) and hypersensitive response (HR)-like cell death. This is accompanied with accumulation of malondialdehyde (MDA), anthocyanin as well as nuclear DNA fragmentation. The transcript abundance of a series of ROS accumulation, cell death, and defense response related genes were up-regulated by the expression of MAPKKK4. Further investigation identified BnaMAPKKK4 elicited ROS through the downstream MPK3. These results indicate that BnaMAPKKK4 and its downstream components function in the ROS-induced cell death. - Highlights: • Expression of rapeseed MAPKKK4 induced ROS accumulation and cell death in leaves. • Cell death induced by MAPKKK4 is associated with membrane lipid peroxidation and DNA fragmentation. • MAPKKK4 interacts with MKK5 and MPK3. • MAPKKK4-induced ROS accumulation and cell death require downstream WIPK and SIPK. • MAPKKK4 is a novel MAPKKK modulating ROS accumulation and cell death.

Rhodamine B-conjugated encrypted vipericidin nonapeptide is a potent toxin to zebrafish and associated with in vitro cytotoxicity.

Science.gov (United States)

Wang, Liang; Chan, Judy Y W; Rêgo, Juciane V; Chong, Cheong-Meng; Ai, Nana; Falcão, Cláudio B; Rádis-Baptista, Gandhi; Lee, Simon M Y

2015-06-01

Animal venoms contain a diverse array of proteins and enzymes that are toxic toward various physiological systems. However, there are also some practical medicinal uses for these toxins including use as anti-bacterial and anti-tumor agents. In this study, we identified a nine-residue cryptic oligopeptide, KRFKKFFKK (EVP50) that is repeatedly encoded in tandem within vipericidin sequences. EVP50 displayed in vivo potent lethal toxicity to zebrafish larvae (LD50=6 μM) when the peptide's N-terminus was chemically conjugated to rhodamine B (RhoB). In vitro, RhoB-conjugated EVP50 (RhoB-EVP50) exhibited a concentration-dependent cytotoxic effect toward MCF-7 and MDA-MB-231 breast cancer cells. In MCF-7 cells, the RhoB-EVP50 nonapeptide accumulated inside the cells within minutes. In the cytoplasm, the RhoB-EVP50 induced extracellular calcium influx and intracellular calcium release. Membrane budding was also observed after incubation with micromolar concentrations of the fluorescent EVP50 conjugate. The conjugate's interference with calcium homeostasis, its intracellular accumulation and its induced membrane dysfunction (budding and vacuolization) seem to act in concert to disrupt the cell circuitry. Contrastively, unconjugated EVP50 peptide did not display neither toxic nor cytotoxic activities in our in vivo and in vitro models. The synergic mechanism of toxicity was restricted to the structurally modified encrypted vipericidin nonapeptide. Copyright © 2015 Elsevier B.V. All rights reserved.

A Polychaete’s Powerful Punch: Venom Gland Transcriptomics of Glycera Reveals a Complex Cocktail of Toxin Homologs

Science.gov (United States)

von Reumont, Björn M.; Richter, Sandy; Hering, Lars; Sykes, Dan; Hetmank, Jörg; Jenner, Ronald A.; Bleidorn, Christoph

2014-01-01

Glycerids are marine annelids commonly known as bloodworms. Bloodworms have an eversible proboscis adorned with jaws connected to venom glands. Bloodworms prey on invertebrates, and it is known that the venom glands produce compounds that can induce toxic effects in animals. Yet, none of these putative toxins has been characterized on a molecular basis. Here we present the transcriptomic profiles of the venom glands of three species of bloodworm, Glycera dibranchiata, Glycera fallax and Glycera tridactyla, as well as the body tissue of G. tridactyla. The venom glands express a complex mixture of transcripts coding for putative toxin precursors. These transcripts represent 20 known toxin classes that have been convergently recruited into animal venoms, as well as transcripts potentially coding for Glycera-specific toxins. The toxins represent five functional categories: Pore-forming and membrane-disrupting toxins, neurotoxins, protease inhibitors, other enzymes, and CAP domain toxins. Many of the transcripts coding for putative Glycera toxins belong to classes that have been widely recruited into venoms, but some are homologs of toxins previously only known from the venoms of scorpaeniform fish and monotremes (stonustoxin-like toxin), turrid gastropods (turripeptide-like peptides), and sea anemones (gigantoxin I-like neurotoxin). This complex mixture of toxin homologs suggests that bloodworms employ venom while predating on macroscopic prey, casting doubt on the previously widespread opinion that G. dibranchiata is a detritivore. Our results further show that researchers should be aware that different assembly methods, as well as different methods of homology prediction, can influence the transcriptomic profiling of venom glands. PMID:25193302

Neutralization of Bacterial YoeBSpn Toxicity and Enhanced Plant Growth in Arabidopsis thaliana via Co-Expression of the Toxin-Antitoxin Genes

Science.gov (United States)

Abu Bakar, Fauziah; Yeo, Chew Chieng; Harikrishna, Jennifer Ann

2016-01-01

Bacterial toxin-antitoxin (TA) systems have various cellular functions, including as part of the general stress response. The genome of the Gram-positive human pathogen Streptococcus pneumoniae harbors several putative TA systems, including yefM-yoeBSpn, which is one of four systems that had been demonstrated to be biologically functional. Overexpression of the yoeBSpn toxin gene resulted in cell stasis and eventually cell death in its native host, as well as in Escherichia coli. Our previous work showed that induced expression of a yoeBSpn toxin-Green Fluorescent Protein (GFP) fusion gene apparently triggered apoptosis and was lethal in the model plant, Arabidopsis thaliana. In this study, we investigated the effects of co-expression of the yefMSpn antitoxin and yoeBSpn toxin-GFP fusion in transgenic A. thaliana. When co-expressed in Arabidopsis, the YefMSpn antitoxin was found to neutralize the toxicity of YoeBSpn-GFP. Interestingly, the inducible expression of both yefMSpn antitoxin and yoeBSpn toxin-GFP fusion in transgenic hybrid Arabidopsis resulted in larger rosette leaves and taller plants with a higher number of inflorescence stems and increased silique production. To our knowledge, this is the first demonstration of a prokaryotic antitoxin neutralizing its cognate toxin in plant cells. PMID:27104531

Neutralization of Bacterial YoeBSpn Toxicity and Enhanced Plant Growth in Arabidopsis thaliana via Co-Expression of the Toxin-Antitoxin Genes

Directory of Open Access Journals (Sweden)

Fauziah Abu Bakar

2016-04-01

Full Text Available Bacterial toxin-antitoxin (TA systems have various cellular functions, including as part of the general stress response. The genome of the Gram-positive human pathogen Streptococcus pneumoniae harbors several putative TA systems, including yefM-yoeBSpn, which is one of four systems that had been demonstrated to be biologically functional. Overexpression of the yoeBSpn toxin gene resulted in cell stasis and eventually cell death in its native host, as well as in Escherichia coli. Our previous work showed that induced expression of a yoeBSpn toxin-Green Fluorescent Protein (GFP fusion gene apparently triggered apoptosis and was lethal in the model plant, Arabidopsis thaliana. In this study, we investigated the effects of co-expression of the yefMSpn antitoxin and yoeBSpn toxin-GFP fusion in transgenic A. thaliana. When co-expressed in Arabidopsis, the YefMSpn antitoxin was found to neutralize the toxicity of YoeBSpn-GFP. Interestingly, the inducible expression of both yefMSpn antitoxin and yoeBSpn toxin-GFP fusion in transgenic hybrid Arabidopsis resulted in larger rosette leaves and taller plants with a higher number of inflorescence stems and increased silique production. To our knowledge, this is the first demonstration of a prokaryotic antitoxin neutralizing its cognate toxin in plant cells.

Saxitoxins and okadaic acid group: accumulation and distribution in invertebrate marine vectors from Southern Chile.

Science.gov (United States)

García, Carlos; Pérez, Francisco; Contreras, Cristóbal; Figueroa, Diego; Barriga, Andrés; López-Rivera, Américo; Araneda, Oscar F; Contreras, Héctor R

2015-01-01

Harmful algae blooms (HABs) are the main source of marine toxins in the aquatic environment surrounding the austral fjords in Chile. Huichas Island (Aysén) has an history of HABs spanning more than 30 years, but there is limited investigation of the bioaccumulation of marine toxins in the bivalves and gastropods from the Region of Aysén. In this study, bivalves (Mytilus chilenses, Choromytilus chorus, Aulacomya ater, Gari solida, Tagelus dombeii and Venus antiqua) and carnivorous gastropods (Argobuccinum ranelliformes and Concholepas concholepas) were collected from 28 sites. Researchers analysed the accumulation of STX-group toxins using a LC with a derivatisation post column (LC-PCOX), while lipophilic toxins (OA-group, azapiracids, pectenotoxins and yessotoxins) were analysed using LC-MS/MS with electrospray ionisation (+/-) in visceral (hepatopancreas) and non-visceral tissues (mantle, adductor muscle, gills and foot). Levels of STX-group and OA-group toxins varied among individuals from the same site. Among all tissue samples, the highest concentrations of STX-group toxins were noted in the hepatopancreas in V. antiqua (95 ± 0.1 μg STX-eq 100 g(-1)), T. dombeii (148 ± 1.4 μg STX-eq 100 g(-1)) and G. solida (3232 ± 5.2 μg STX-eq 100 g(-1); p concholepas (81 ± 0.7 μg STX-eq 100 g(-1)) and T. dombeii (114 ± 1.2 μg STX-eq 100 g(-1)). The highest variability of toxins was detected in G. solida, where high levels of carbamate derivatives were identified (GTXs, neoSTX and STX). In addition to the detected hydrophilic toxins, OA-group toxins were detected (OA and DTX-1) with an average ratio of ≈1:1. The highest levels of OA-group toxins were in the foot of C. concholepas, with levels of 400.3 ± 3.6 μg OA eq kg(-1) (p mantle > adductor muscle for the STX-group toxins and foot > digestive gland for the OA-group toxins. These results gave a better understanding of the variability and compartmentalisation of STX-group and OA-group toxins in different

The Action of Botulinum Toxin at the Neuromuscular Junction

Science.gov (United States)

1980-12-22

fast - twitch " (gastrocnemius) and " slow - twitch " (soleus) muscles ... muscle fibers -"_re not significantly affected by the toxin. It is interesting to note that, although fast - twitch and slow - twitch mucles were...Duchen LW: An electron microscopic study of the changes induced by borulinum o::in in the motor end-plates of slow and fast skeletal muscle fibres of

Electric-field induced spin accumulation in the Landau level states of topological insulator thin films

Science.gov (United States)

Siu, Zhuo Bin; Chowdhury, Debashree; Basu, Banasri; Jalil, Mansoor B. A.

2017-08-01

A topological insulator (TI) thin film differs from the more typically studied thick TI system in that the former has both a top and a bottom surface where the states localized at both surfaces can couple to one other across the finite thickness. An out-of-plane magnetic field leads to the formation of discrete Landau level states in the system, whereas an in-plane magnetization breaks the angular momentum symmetry of the system. In this work, we study the spin accumulation induced by the application of an in-plane electric field to the TI thin film system where the Landau level states and inter-surface coupling are simultaneously present. We show, via Kubo formula calculations, that the in-plane spin accumulation perpendicular to the magnetization due to the electric field vanishes for a TI thin film with symmetric top and bottom surfaces. A finite in-plane spin accumulation perpendicular to both the electric field and magnetization emerges upon applying either a differential magnetization coupling or a potential difference between the two film surfaces. This spin accumulation results from the breaking of the antisymmetry of the spin accumulation around the k-space equal-energy contours.

Augmenting the Efficacy of Immunotoxins and Other Targeted Protein Toxins by Endosomal Escape Enhancers

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Hendrik Fuchs

2016-07-01

Full Text Available The toxic moiety of almost all protein-based targeted toxins must enter the cytosol of the target cell to mediate its fatal effect. Although more than 500 targeted toxins have been investigated in the past decades, no antibody-targeted protein toxin has been approved for tumor therapeutic applications by the authorities to date. Missing efficacy can be attributed in many cases to insufficient endosomal escape and therefore subsequent lysosomal degradation of the endocytosed toxins. To overcome this drawback, many strategies have been described to weaken the membrane integrity of endosomes. This comprises the use of lysosomotropic amines, carboxylic ionophores, calcium channel antagonists, various cell-penetrating peptides of viral, bacterial, plant, animal, human and synthetic origin, other organic molecules and light-induced techniques. Although the efficacy of the targeted toxins was typically augmented in cell culture hundred or thousand fold, in exceptional cases more than million fold, the combination of several substances harbors new problems including additional side effects, loss of target specificity, difficulties to determine the therapeutic window and cell type-dependent variations. This review critically scrutinizes the chances and challenges of endosomal escape enhancers and their potential role in future developments.

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

Science.gov (United States)

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.

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

Science.gov (United States)

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

Cationic uremic toxins affect human renal proximal tubule cell functioning through interaction with the organic cation transporter.

Science.gov (United States)

Schophuizen, Carolien M S; Wilmer, Martijn J; Jansen, Jitske; Gustavsson, Lena; Hilgendorf, Constanze; Hoenderop, Joost G J; van den Heuvel, Lambert P; Masereeuw, Rosalinde

2013-12-01

Several organic cations, such as guanidino compounds and polyamines, have been found to accumulate in plasma of patients with kidney failure due to inadequate renal clearance. Here, we studied the interaction of cationic uremic toxins with renal organic cation transport in a conditionally immortalized human proximal tubule epithelial cell line (ciPTEC). Transporter activity was measured and validated in cell suspensions by studying uptake of the fluorescent substrate 4-(4-(dimethylamino)styryl)-N-methylpyridinium-iodide (ASP(+)). Subsequently, the inhibitory potencies of the cationic uremic toxins, cadaverine, putrescine, spermine and spermidine (polyamines), acrolein (polyamine breakdown product), guanidine, and methylguanidine (guanidino compounds) were determined. Concentration-dependent inhibition of ASP(+) uptake by TPA, cimetidine, quinidine, and metformin confirmed functional endogenous organic cation transporter 2 (OCT2) expression in ciPTEC. All uremic toxins tested inhibited ASP(+) uptake, of which acrolein required the lowest concentration to provoke a half-maximal inhibition (IC50 = 44 ± 2 μM). A Dixon plot was constructed for acrolein using three independent inhibition curves with 10, 20, or 30 μM ASP(+), which demonstrated competitive or mixed type of interaction (K i = 93 ± 16 μM). Exposing the cells to a mixture of cationic uremic toxins resulted in a more potent and biphasic inhibitory response curve, indicating complex interactions between the toxins and ASP(+) uptake. In conclusion, ciPTEC proves a suitable model to study cationic xenobiotic interactions. Inhibition of cellular uptake transport was demonstrated for several uremic toxins, which might indicate a possible role in kidney disease progression during uremia.

A portable cell-based optical detection device for rapid detection of Listeria and Bacillus toxins

Science.gov (United States)

Banerjee, Pratik; Banada, Padmapriya P.; Rickus, Jenna L.; Morgan, Mark T.; Bhunia, Arun K.

2005-11-01

A mammalian cell-based optical biosensor was built to detect pathogenic Listeria and Bacillus species. This sensor measures the ability of the pathogens to infect and induce cytotoxicity on hybrid lymphocyte cell line (Ped-2E9) resulting in the release of alkaline phosphatase (ALP) that can be detected optically using a portable spectrophotometer. The Ped-2E9 cells were encapsulated in collagen gel matrices and grown in 48-well plates or in specially designed filtration tube units. Toxin preparations or bacterial cells were introduced and ALP release was assayed after 3-5 h. Pathogenic L. monocytogenes strains or the listeriolysin toxins preparation showed cytotoxicity ranging from 55% - 92%. Toxin preparations (~20 μg/ml) from B. cereus strains showed 24 - 98% cytotoxicity. In contrast, a non-pathogenic L. innocua (F4247) and a B. substilis induced only 2% and 8% cytotoxicity, respectively. This cell-based detection device demonstrates its ability to detect the presence of pathogenic Listeria and Bacillus species and can potentially be used onsite for food safety or in biosecurity application.

Numerical and analytical treatment on peristaltic flow of Williamson fluid in the occurrence of induced magnetic field

Energy Technology Data Exchange (ETDEWEB)

Akram, Safia, E-mail: safia_akram@yahoomail.com [Department of Basic Sciences, Military College of Signals, National University of Sciences and Technology (Pakistan); Nadeem, S. [Department of Mathematics, Quaid-i-Azam University 45320, Islamabad 44000 (Pakistan); Hanif, M. [Department of Basic Sciences, Military College of Signals, National University of Sciences and Technology (Pakistan)

2013-11-15

In this paper the effects of induced magnetic field on the peristaltic transport of a Williamson fluid model in an asymmetric channel has been investigated. The problem is simplified by using long wave length and low Reynolds number approximations. The perturbation and numerical solutions have been presented. The expressions for pressure rise, pressure gradient, stream function, magnetic force function, current density distribution have been computed. The results of pertinent parameters have been discussed graphically. The trapping phenomena for different wave forms have been also discussed. - highlights: • The main motivation of this work is that we want to see the behavior of peristaltic flow of Williamson fluid in the occurrence of induced magnetic field. In literature no attempt is taken to discuss the lateral Numerical and analytical treatment on peristaltic flow of Williamson fluid in the occurrence of induced magnetic field. • We do not want to fill the gap in literature after studying this.

Numerical and analytical treatment on peristaltic flow of Williamson fluid in the occurrence of induced magnetic field

International Nuclear Information System (INIS)

Akram, Safia; Nadeem, S.; Hanif, M.

2013-01-01

In this paper the effects of induced magnetic field on the peristaltic transport of a Williamson fluid model in an asymmetric channel has been investigated. The problem is simplified by using long wave length and low Reynolds number approximations. The perturbation and numerical solutions have been presented. The expressions for pressure rise, pressure gradient, stream function, magnetic force function, current density distribution have been computed. The results of pertinent parameters have been discussed graphically. The trapping phenomena for different wave forms have been also discussed. - highlights: • The main motivation of this work is that we want to see the behavior of peristaltic flow of Williamson fluid in the occurrence of induced magnetic field. In literature no attempt is taken to discuss the lateral Numerical and analytical treatment on peristaltic flow of Williamson fluid in the occurrence of induced magnetic field. • We do not want to fill the gap in literature after studying this

Tracking micro-optical resonances for identifying and sensing novel procaspase-3 protein marker released from cell cultures in response to toxins

International Nuclear Information System (INIS)

Chen, Ying-Jen; Vollmer, Frank; Xiang, Wei; Klucken, Jochen

2016-01-01

The response of cells to toxins is commonly investigated by detecting intracellular markers for cell death, such as caspase proteins. This requires the introduction of labels by the permeabilization or complete lysis of cells. Here we introduce a non-invasive tool for monitoring a caspase protein in the extracellular medium. The tool is based on highly sensitive optical micro-devices, referred to as whispering-gallery mode biosensors (WGMBs). WGMBs are functionalized with antibodies for the specific and label-free detection of procaspase-3 released from human embryonic kidney HEK293 and neuroglioma H4 cells after introducing staurosporine and rotenone toxins, respectively. Additional tests show that the extracellular accumulation of procaspase-3 is concomitant with a decrease in cell viability. The hitherto unknown release of procaspase-3 from cells in response to toxins and its accumulation in the medium is further investigated by Western blot, showing that the extracellular detection of procaspase-3 is interrelated with cytotoxicity of alpha-synuclein protein (aSyn) overexpressed in H4 cells. These studies provide evidence for procaspase-3 as a novel extracellular biomarker for cell death, with applications in cytotoxicity tests. Such WGMBs could be applied to further identify as-yet unknown extracellular biomarkers using established antibodies against intracellular antigens. (paper)

Synthetic cold-inducible promoter enhances recombinant protein accumulation during Agrobacterium-mediated transient expression in Nicotiana excelsior at chilling temperatures.

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Gerasymenko, I M; Sheludko, Y V

2017-07-01

To exploit cold-inducible biochemical processes beneficial for foreign mRNA transcription, translation and storage, as well as protein product stability, during Agrobacterium-mediated transient expression. The efficiency of three different 5'-regulatory sequences to achieve transient expression of the GFP-based reporter gene under chilling conditions (6-8 °C since the 3rd day post inoculation) was compared. We studied the upstream sequences of a cold-inducible Arabidopsis thaliana cor15a gene, the core element of 35S CaMV promoter fused to the TMV omega 5'-UTR, and the synthetic promoter including the 35S core sequence and two binding sites for cold-inducible CBF transcription factors (P_DRE::35S). Cultivation of plants transiently expressing reporter gene under control of the synthetic P_DRE::35S promoter under chilling conditions since the 3rd dpi led to the reliably higher reporter accumulation as compared to the other tested regulatory sequences under chilling or greenhouse conditions. Reporter protein fluorescence under chilling conditions using P_DRE::35S reached 160% as compared to the transient expression in the greenhouse. Period of transient expression considerably extended if plants were cultivated at chilling temperature since the 3rd dpi: reporter protein fluorescence reached its maximum at the 20th dpi and was detected in leaves up to the 65th dpi. The enhanced protein accumulation at low temperature was accompanied by the prolonged period of corresponding mRNA accumulation. Transient expression under chilling conditions using synthetic cold-inducible promoter enhances target protein accumulation and may decrease greenhouse heating expenses.

SVM-based prediction of propeptide cleavage sites in spider toxins identifies toxin innovation in an Australian tarantula.

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Emily S W Wong

Full Text Available 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

Microalgal toxin(s): characteristics and importance

African Journals Online (AJOL)

Prokaryotic and eukaryotic microalgae produce a wide array of compounds with biological activities. These include antibiotics, algicides, toxins, pharmaceutically active compounds and plant growth regulators. Toxic microalgae, in this sense, are common only among the cyanobacteria and dinoflagellates. The microalgal ...

Isolation and characterization of delta toxin from the venom of Crotalus durissus terrificus

International Nuclear Information System (INIS)

Campos, Lucelia de Almeida

2006-01-01

The Crotalus durissus terrificus venom has been so far described as being of low complexity, with four major components described: convulxin, gyroxin, crotoxin and crotamine. In recent studies, other components of this venom were characterized as, for example, an analgesic factor. In 1980, Vital Brazil predicted the existence of a toxin which could be involved in platelet aggregation, and named it delta toxin. However, this toxin has never been isolated or characterized. The aim of the present work was to purify and characterize this toxin. After FPLC size exclusion chromatography followed by reverse phase HPLC, an homogeneous fraction was obtained, with a molecular weight of 14,074.92 Da. When analyzed by SOS-PAGE, this toxin presented an anomalous behavior, with a molecular weight of 14 kDa, while in 2D gels, spots around 40 kDa and with an isoelectrical point between 4 and 5 were observed suggesting isoforms with glicosilation microheterogeneity. After trypsin digestion, the fragments were submitted to the swissprot databank showing high homology (43% coverage, 15 matching peptides) with trocarin, a prothrombin activator from Tropidechis carinatus. These data were further confirmed by aminoacid analysis. The toxin was tested for its ability to activate factor II and X using synthetic substrates. Our data indicate a direct activation of factor X. The same toxin also behaved as a potent direct platelet aggregation activator on washed platelets. Assays with specific inhibitors indicate that neither metalloproteinase, nor serinoproteinase or t lectin domains are involved in the aggregating activity, since EDTA, benzamidin and D-galactose did not inhibit the toxin. In the present work, we were able to identify, purify and characterize a new toxin from the brazilian rattlesnake. It behaved as predicted by Vital-Brazil and displayed direct factor X activating properties, also inducing platelet aggregation, even at low concentrations. Our data also indicate that it is

Immunotoxins: The Role of the Toxin

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David FitzGerald

2013-08-01

Full Text Available Immunotoxins are antibody-toxin bifunctional molecules that rely on intracellular toxin action to kill target cells. Target specificity is determined via the binding attributes of the chosen antibody. Mostly, but not exclusively, immunotoxins are purpose-built to kill cancer cells as part of novel treatment approaches. Other applications for immunotoxins include immune regulation and the treatment of viral or parasitic diseases. Here we discuss the utility of protein toxins, of both bacterial and plant origin, joined to antibodies for targeting cancer cells. Finally, while clinical goals are focused on the development of novel cancer treatments, much has been learned about toxin action and intracellular pathways. Thus toxins are considered both medicines for treating human disease and probes of cellular function.

Furfural induces reactive oxygen species accumulation and cellular damage in Saccharomyces cerevisiae

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Slininger Patricia J

2010-01-01

Full Text Available Abstract Background Biofuels offer a viable alternative to petroleum-based fuel. However, current methods are not sufficient and the technology required in order to use lignocellulosic biomass as a fermentation substrate faces several challenges. One challenge is the need for a robust fermentative microorganism that can tolerate the inhibitors present during lignocellulosic fermentation. These inhibitors include the furan aldehyde, furfural, which is released as a byproduct of pentose dehydration during the weak acid pretreatment of lignocellulose. In order to survive in the presence of furfural, yeast cells need not only to reduce furfural to the less toxic furan methanol, but also to protect themselves and repair any damage caused by the furfural. Since furfural tolerance in yeast requires a functional pentose phosphate pathway (PPP, and the PPP is associated with reactive oxygen species (ROS tolerance, we decided to investigate whether or not furfural induces ROS and its related cellular damage in yeast. Results We demonstrated that furfural induces the accumulation of ROS in Saccharomyces cerevisiae. In addition, furfural was shown to cause cellular damage that is consistent with ROS accumulation in cells which includes damage to mitochondria and vacuole membranes, the actin cytoskeleton and nuclear chromatin. The furfural-induced damage is less severe when yeast are grown in a furfural concentration (25 mM that allows for eventual growth after an extended lag compared to a concentration of furfural (50 mM that prevents growth. Conclusion These data suggest that when yeast cells encounter the inhibitor furfural, they not only need to reduce furfural into furan methanol but also to protect themselves from the cellular effects of furfural and repair any damage caused. The reduced cellular damage seen at 25 mM furfural compared to 50 mM furfural may be linked to the observation that at 25 mM furfural yeast were able to exit the furfural-induced

Orphan Toxin OrtT (YdcX) of Escherichia coli Reduces Growth during the Stringent Response

Science.gov (United States)

2015-01-29

antimicrobials trimethoprim and sulfamethoxazole; these antimicrobials induce the stringent response by inhibiting tetrahydrofolate synthesis...in the presence of both antimicrobials trimethoprim and sulfamethoxazole; these antimicrobials induce the stringent response by inhibiting...level [20]. Toxins 2015, 7 301 Despite these difficulties in determining physiological roles, TA systems are clearly phage inhibition systems

On The Flow of Maxwell Fluid Between Two Walls Induced By A ...

African Journals Online (AJOL)

The flow of a Maxwell fluid between two side walls induced by a constant accelerating plate is revisited. In the present investigation, we employed asymptotic technique by assuming small and large relaxation times λ. We proved the uniqueness of our solution based on some simplifying assumption; the result shows that λ ...

Radioimmunoassay for yeast killer toxin from Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Siddiqui, F.A.; Bussey, H.

1981-01-01

A radioimmunoassay was developed for the K1 killer toxin from strain T158C/S14a of Saccharomyces cerevisiae. Iodine 125-labelled toxin was made to a specific activity of 100 μCi/mg of protein. Antibody to purified toxin was prepared in rabbits using toxin cross-linked to itself. These antibodies, partially purified by 50 percent ammonium sulfate precipitation and Sepharose CL-6B column chromatography, produced one precipitation band with killer toxin and bound 125 I-labelled toxin in a radioimmunoassay. The antibody preparation also bound with the toxins from another K1 killer, A364A, and three chromosomal superkiller mutants derived from it. (auth)

Marine and freshwater toxins.

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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

Propensity of tampons and barrier contraceptives to amplify Staphylococcus aureusToxic shock syndrome toxin-I.

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Tierno, P M; Hanna, B A

1994-01-01

Although the incidence of reported cases of toxic shock syndrome (TSS) has declined in recent years, the disease continues to occur in menstruating women using the newer, less-absorbent tampons or barrier contraceptives. Extant tampons and other vaginal devices were tested for the ability to induce TSS toxin-1 (TSST-1) by a TSS strain of Staphylococcus aureus MN8, a known high-toxin producer. Tested for the first time were 20 varieties of tampons, including 2 all-cotton brands newly introduced in the United States, a polyurethane contraceptive sponge, a latex diaphragm, and a polymer menstrual collection cup. All products were washed in sterile distilled water prior to use to reduce the effect of leachable chemicals. Duplicate experiments with unwashed products were also performed. Entire tampons and other test products were immersed in brain heart infusion broth plus yeast extract (BHIY) and inoculated with S. aureus MN8, a known TSST-1 producer. After incubation, the culture supernatants were assayed for TSST-1 by gel immunodiffusion. Except for all-cotton tampons, greater amounts of TSST-1 were detected in the supernatant fluid of washed tampons than detected in those which were not washed. While TSST-1 levels in unwashed non-cotton tampons ranged from 0.5 to 8 microg/ml, when these products were washed, TSST-1 levels increased to 2-32 microg/ml. In all-cotton tampons, whether washed or not, there was no detectable TSST-1. The propensity for all-cotton tampons not to amplify TSST-1 in vitro suggests they would lower the risk for tampon-associated TSS.

Human Tear Fluid Reduces Culturability of Contact Lens Associated Pseudomonas aeruginosa Biofilms but Induces Expression of the Virulence Associated Type III Secretion System

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Wu, Yvonne T.; Tam, Connie; Zhu, Lucia S.; Evans, David J.; Fleiszig, Suzanne M. J.

2017-01-01

Purpose The type III secretion system (T3SS) is a significant virulence determinant for Pseudomonas aeruginosa. Using a rodent model, we found that contact lens (CL)-related corneal infections were associated with lens surface biofilms. Here, we studied the impact of human tear fluid on CL-associated biofilm growth and T3SS expression. Methods P. aeruginosa biofilms were formed on contact lenses for up to 7 days with or without human tear fluid, then exposed to tear fluid for 5 or 24 h. Biofilms were imaged using confocal microscopy. Bacterial culturability was quantified by viable counts, and T3SS gene expression measured by RT-qPCR. Controls included trypticase soy broth, PBS and planktonic bacteria. Results With or without tear fluid, biofilms grew to ~108 cfu viable bacteria by 24 h. Exposing biofilms to tear fluid after they had formed without it on lenses reduced bacterial culturability ~180-fold (pbacteria [5.46 ± 0.24-fold for T3SS transcriptional activitor exsA (p=.02), and 3.76 ± 0.36-fold for T3SS effector toxin exoS (p=.01)]. Tear fluid further enhanced exsA and exoS expression in CL-grown biofilms, but not planktonic bacteria, by 2.09 ± 0.38-fold (p = 0.04) and 1.89 ± 0.26-fold (p<.001), respectively. Conclusions Considering the pivitol role of the T3SS in P. aeruginosa infections, its induction in CL-grown P. aeruginosa biofilms by tear fluid might contribute to the pathogenesis of CL-related P. aeruginosa keratitis. PMID:27670247

External accumulation of radionuclide in hepatic hydrothorax

International Nuclear Information System (INIS)

Albin, R.J.; Johnston, G.S.

1989-01-01

Hepatic hydrothorax is a complication in approximately 5% of patients with cirrhosis. Ascites is almost always present and helps to suggest the correct diagnosis. However, when ascites is absent, radionuclide imaging has proven to be helpful in establishing that the pleural effusion originated from ascitic fluid. When pleural fluid is rapidly removed, such as by thoracostomy tube drainage, the radioisotope may accumulate outside the thorax and produce a negative scan of the chest. When the radionuclide scan is nondiagnostic and the pleural space is being rapidly drained, the pleural fluid collecting system should always be imaged before rejecting a diagnosis of hepatic hydrothorax

In vivo binding of the Cry11Bb toxin of Bacillus thuringiensis subsp. medellin to the midgut of mosquito larvae (Diptera: Culicidae

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Ruiz Lina María

2004-01-01

Full Text Available Bacillus thuringiensis subsp. medellin produces numerous proteins among which 94 kDa known as Cry11Bb, has mosquitocidal activity. The mode of action of the Cry11 proteins has been described as similar to those of the Cry1 toxins, nevertheless, the mechanism of action is still not clear. In this study we investigated the in vivo binding of the Cry11Bb toxin to the midgut of the insect species Anopheles albimanus, Aedes aegypti, and Culex quinquefasciatus by immunohistochemical analysis. Spodoptera frugiperda was included as negative control. The Cry11Bb protein was detected on the apical microvilli of the midgut epithelial cells, mostly on the posterior midgut and gastric caeca of the three mosquito species. Additionally, the toxin was detected in the Malpighian tubules of An. albimanus, Ae. aegypti, Cx. quinquefasciatus, and in the basal membrane of the epithelial cells of Ae. aegypti midgut. No toxin accumulation was observed in the peritrophic membrane of any of the mosquito species studied. These results confirm that the primary site of action of the Cry11 toxins is the apical membrane of the midgut epithelial cells of mosquito larvae.

Role of Botulinum Toxin in Depression.

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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.

Paralytic shellfish toxins in the Atlantic horse mackerel (Trachurus trachurus over a bloom of Gymnodinium catenatum: the prevalence of decarbamoylsaxitoxin in the marine food web

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Sandra Lage

2013-03-01

Full Text Available This study reports the accumulation of paralytic shellfish toxins (PSTs in Atlantic horse mackerel (Trachurus trachurus over a bloom of the toxigenic dinoflagellate Gymnodinium catenatum. High levels of toxins, up to 4800 μg STXeq kg–1, were registered at the peak of the bloom (5.0 103 cells l–1. The suite of individual PSTs was examined. Decarbamoylsaxitoxin (dcSTX and B1 constituted nearly 90% of toxins (on a molar basis determined in mackerel. This profile of toxins markedly differs from the known profile of toxins produced by G. catenatum strains isolated from the Portuguese coast, which is dominated by N-sulfocarbamoyl toxins, in particular the C1+2 toxins. The prevalence of the potent dcSTX in the pelagic environment and its transfer through the marine food web is highlighted in this study. Atlantic horse mackerel is identified as a high potential vector of PSTs along the Portuguese coast. This fish species has a central position in the marine food web, being an important predator of zooplankton and at the same time an important diet item of top predators. This study reveals bioaccumulation values that are important for evaluating potential impacts of blooms of PST-producing dinoflagellates on marine ecosystems or their components, such as fish.

Botulinum toxin therapy for limb dystonias.

Science.gov (United States)

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.

Effect of wortmannin and phorbol ester on Paramecium fluid-phase uptake in the presence of transferrin

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J Wiejak

2009-12-01

Full Text Available The kinetics of the uptake of the fluid phase marker Lucifer Yellow (LY, and its alteration by wortmannin, an inhibitor of phosphatidylinositol-3 kinase (PI-3K, and the PKC modulators: GF 109203 X, an inhibitor, and phorbol ester, an activator was studied in eukaryotic model Paramecium aurelia. Spectrophotometric quantification of LY accumulation was performed in the presence or absence of transferrin, a marker of receptor-mediated endocytosis. Internalization of LY showed a curvilinear kinetics: the high initial rate of LYuptake (575 ng LY/ mg protein /hr decreased almost 5-fold within 15 min, reaching plateau at 126 ng/ mg protein /hr. Transferrin induced a small increase (7.5% in the fluid phase uptake rate (after 5 min followed by a small decrease at longer incubation times. Lucifer Yellow and transferrin (visualized by streptavidin– FITC were localized in Paramecium by 3-D reconstruction by confocal microscopy. LY showed a scattered, diffuse fluorescence typical of fluid phase uptake whereas transferrin accumulated in membrane-surrounded endosomes. Wortmannin did not affect LY accumulation but decreased it when transferrin was present in the incubation medium. This suggests an effect on the transferrin uptake pathway, presumably on the stage of internalization in “mixing” endosomes to which transferrin and LY were targeted. Phorbol ester diminished LY accumulation by 22% and this effect persisted up to 25 min of incubation. PKC inhibitor did not affect LY uptake. However, in the presence of transferrin, the LY uptake increased within the first 15 minutes followed by a rapid 20% decrease in comparison to the control. Such an effect of PKC modulators suggests that PMA action on fluid phase uptake is not directly mediated by PKC.

Military Importance of Natural Toxins and Their Analogs

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Vladimír Pitschmann

2016-04-01

Full Text Available 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.

Military Importance of Natural Toxins and Their Analogs.

Science.gov (United States)

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.

Accumulation of methylglyoxal increases the advanced glycation end-product levels in DRG and contributes to lumbar disk herniation-induced persistent pain.

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Liu, Cui-Cui; Zhang, Xin-Sheng; Ruan, Yu-Ting; Huang, Zhu-Xi; Zhang, Su-Bo; Liu, Meng; Luo, Hai-Jie; Wu, Shao-Ling; Ma, Chao

2017-08-01

Lumbar disk herniation (LDH) with discogenic low back pain and sciatica is a common and complicated musculoskeletal disorder. The underlying mechanisms are poorly understood, and there are no effective therapies for LDH-induced pain. In the present study, we found that the patients who suffered from LDH-induced pain had elevated plasma methylglyoxal (MG) levels. In rats, implantation of autologous nucleus pulposus (NP) to the left lumbar 5 spinal nerve root, which mimicked LDH, induced mechanical allodynia, increased MG level in plasma and dorsal root ganglion (DRG), and enhanced the excitability of small DRG neurons (DRG neurons ex vivo increased the number of action potentials evoked by depolarizing current pulses. Furthermore, inhibition of MG accumulation by aminoguanidine attenuated the enhanced excitability of small DRG neurons and the mechanical allodynia induced by NP implantation. In addition, NP implantation increased levels of advanced glycation end products (AGEs) in DRG, and intrathecal injection of MG-derived AGEs induced the mechanical allodynia and DRG neuronal hyperactivity. Intrathecal injection of MG also significantly increased the expression of AGEs in DRG. Importantly, scavenging of MG by aminoguanidine also attenuated the increase in AGEs induced by NP implantation. These results suggested that LDH-induced MG accumulation contributed to persistent pain by increasing AGE levels. Thus generation of AGEs from MG may represent a target for treatment of LDH-induced pain. NEW & NOTEWORTHY Our study demonstrates that methylglyoxal accumulation via increasing advanced glycation end-product levels in dorsal root ganglion contributes to the persistent pain induced by lumbar disk herniation, which proposed potential targets for the treatment of lumbar disk herniation-induced persistent pain. Copyright © 2017 the American Physiological Society.

Activating transcription factor 6 mediates oxidized LDL-induced cholesterol accumulation and apoptosis in macrophages by up-regulating CHOP expression.

Science.gov (United States)

Yao, Shutong; Zong, Chuanlong; Zhang, Ying; Sang, Hui; Yang, Mingfeng; Jiao, Peng; Fang, Yongqi; Yang, Nana; Song, Guohua; Qin, Shucun

2013-01-01

This study was to explore whether activating transcription factor 6 (ATF6), an important sensor to endoplasmic reticulum (ER) stress, would mediate oxidized low-density lipoprotein (ox-LDL)- induced cholesterol accumulation and apoptosis in cultured macrophages and the underlying molecular mechanisms. Intracellular lipid droplets and total cholesterol levels were assayed by oil red O staining and enzymatic colorimetry, respectively. Cell viability and apoptosis were determined using MTT assay and AnnexinV-FITC apoptosis detection kit, respectively. The nuclear translocation of ATF6 in cells was detected by immunofluorescence analysis. Protein and mRNA levels were examined by Western blot analysis and real time-PCR, respectively. ATF6 siRNA was transfected to RAW264.7 cells by lipofectamin. Exposure of cells to ox-LDL induced glucose-regulated protein 78 (GRP78). C/EBP homologous protein (CHOP), a key-signaling component of ER stress-induced apoptosis, was up-regulated in ox-LDL-treated cells. ATF6, a factor that positively regulates CHOP expression, was activated by ox-LDL in a concentration- and time- dependent manner. The role of the ATF6-mediated ER stress pathway was further confirmed through the siRNA-mediated knockdown of ATF6, which attenuated ox-LDL-induced upregulation of CHOP, cholesterol accumulation and apoptosis in macrophages. In addition, the phosphorylation of double-stranded RNA-activated protein kinase-like endoplasmic reticulum kinase (PERK), another factor that positively regulates CHOP expression, was induced in the presence of ox-LDL, and PERK-specific siRNA also inhibited the ox-LDL-induced upregulation of CHOP and apoptosis in RAW264.7 cells. These results demonstrate that ER stress-related proteins, particularly ATF6 and its downstream molecule CHOP, are involved in ox-LDL-induced cholesterol accumulation and apoptosis in macrophages.

The Hall-induced stability of gravitating fluids

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Karmakar, P. K.; Goutam, H. P.

2018-05-01

We analyze the stability behavior of low-density partially ionized self-gravitating magnetized unbounded dusty plasma fluid in the presence of the Hall diffusion effects (HDEs) in the non-ideal magnetohydrodynamic (MHD) equilibrium framework. The effects of inhomogeneous self-gravity are methodically included in the basic model tapestry. Application of the Fourier plane-wave perturbative treatment decouples the structuration representative parameters into a linear generalized dispersion relation (sextic) in a judicious mean-fluid approximation. The dispersion analysis shows that the normal mode, termed as the gravito-magneto-acoustic (GMA) mode, is drastically modified due to the HDEs. This mode is highly dispersive, and driven unstable by the Hall current resulting from the symmetry-breaking of electrons and ions relative to the magnetic field. The mode feature, which is derived from a modified induction with the positive Hall, is against the ideal MHD. It is further demonstrated that the HDEs play stabilizing roles by supporting the cloud against gravitational collapse. Provided that the HDEs are concurrently switched off, the collapse occurs on the global spatial scale due to enhanced inward accretion of the gravitating dust constituents. It is seen explicitly that the enhanced dust-charge leads to stabilizing effects. Besides, the Hall-induced fluctuations, as propagatory wave modes, exhibit both normal and anomalous dispersions. The reliability checkup of the entailed results as diverse corollaries and special cases are illustratively discussed in the panoptic light of the earlier paradigmatic predictions available in the literature.

Lipid accumulation in human breast cancer cells injured by iron depletors.

Science.gov (United States)

De Bortoli, Maida; Taverna, Elena; Maffioli, Elisa; Casalini, Patrizia; Crisafi, Francesco; Kumar, Vikas; Caccia, Claudio; Polli, Dario; Tedeschi, Gabriella; Bongarzone, Italia

2018-04-03

Current insights into the effects of iron deficiency in tumour cells are not commensurate with the importance of iron in cell metabolism. Studies have predominantly focused on the effects of oxygen or glucose scarcity in tumour cells, while attributing insufficient emphasis to the inadequate supply of iron in hypoxic regions. Cellular responses to iron deficiency and hypoxia are interlinked and may strongly affect tumour metabolism. We examined the morphological, proteomic, and metabolic effects induced by two iron chelators-deferoxamine (DFO) and di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT)-on MDA-MB-231 and MDA-MB-157 breast cancer cells. These chelators induced a cytoplasmic massive vacuolation and accumulation of lipid droplets (LDs), eventually followed by implosive, non-autophagic, and non-apoptotic death similar to methuosis. Vacuoles and LDs are generated by expansion of the endoplasmic reticulum (ER) based on extracellular fluid import, which includes unsaturated fatty acids that accumulate in LDs. Typical physiological phenomena associated with hypoxia are observed, such as inhibition of translation, mitochondrial dysfunction, and metabolic remodelling. These survival-oriented changes are associated with a greater expression of epithelial/mesenchymal transcription markers. Iron starvation induces a hypoxia-like program able to scavenge nutrients from the extracellular environment, and cells assume a hypertrophic phenotype. Such survival strategy is accompanied by the ER-dependent massive cytoplasmic vacuolization, mitochondrial dysfunctions, and LD accumulation and then evolves into cell death. LDs containing a greater proportion of unsaturated lipids are released as a consequence of cell death. The consequence of the disruption of iron metabolism in tumour tissue and the effects of LDs on intercellular communication, cancer-inflammation axis, and immunity remain to be explored. Considering the potential benefits, these are crucial

Methotrexate-Induced Accumulation of Fluorescent Annexin V in Collagen-Induced Arthritis

Directory of Open Access Journals (Sweden)

Andreas Wunder

2005-01-01

Full Text Available We examined the accumulation of Cy5.5-labeled annexin V in the paws of mice with and without collagen-induced arthritis, with and without methotrexate (MTX treatment, by near-infrared fluorescence imaging. Fluorescence reflectance imaging (FRI of paws was performed 48 hr after MTX injection and at 10 min and 3 hr after the injection of Cy5.5-annexin V (1 nmol dye per mouse. With arthritic paws, MTX treatment caused a 7-fold increase in fluorescence intensity compared with the paws of untreated mice and a 4-fold increase compared to nonarthritic paws of MTX-treated mice (p < .001 each. Tissue samples of paws were examined histologically for Cy5.5 fluorescence and by TUNEL staining for apoptosis. Cy5.5-annexin V was seen in the hyperplastic synovia of MTX-treated mice, and TUNEL staining for apoptosis showed apoptotic cells in the hyperplastic synovia. Monitoring the uptake of Cy5.5-annexin V in arthritic paws by FRI provided a method of assessing a response to MTX, a response that was readily quantitated with simple instrumentation and that occurred before conventional measurements of treatment response.

Modeling fluid forces and response of a tube bundle in cross-flow induced vibrations

International Nuclear Information System (INIS)

Khushnood, Shahab; Khan, Zaffar M.; Malik, M. Afzaal; Koreshi, Zafarullah; Khan, Mahmood Anwar

2003-01-01

Flow induced vibrations occur in process heat exchangers, condensers, boilers and nuclear steam generators. Under certain flow conditions and fluid velocities, the fluid forces result in tube vibrations and possible damage of tube, tube sheet or baffle due to fretting and fatigue. Prediction of these forces is an important consideration. The characteristics of vibration depend greatly on the fluid dynamic forces and structure of the tube bundle. It is undesirable for the tube bundles to vibrate excessively under normal operating conditions because tubes wear and eventual leakage can occur leading to costly shutdowns. In this paper modeling of fluid forces and vibration response of a tube in a heat exchanger bundle has been carried out. Experimental validation has been performed on an existing refinery heat exchanger tube bundle. The target tube has been instrumented with an accelerometer and strain gages. The bundle has been studied for pulse, sinusoidal and random excitations. Natural frequencies and damping of the tubes have also been computed. Experimental fluid forces and response shows a reasonable agreement with the predictions. (author)

Algal Toxins Alter Copepod Feeding Behavior

Science.gov (United States)

Hong, Jiarong; Talapatra, Siddharth; Katz, Joseph; Tester, Patricia A.; Waggett, Rebecca J.; Place, Allen R.

2012-01-01

Using digital holographic cinematography, we quantify and compare the feeding behavior of free-swimming copepods, Acartia tonsa, on nutritional prey (Storeatula major) to that occurring during exposure to toxic and non-toxic strains of Karenia brevis and Karlodinium veneficum. These two harmful algal species produce polyketide toxins with different modes of action and potency. We distinguish between two different beating modes of the copepod’s feeding appendages–a “sampling beating” that has short durations (<100 ms) and involves little fluid entrainment and a longer duration “grazing beating” that persists up to 1200 ms and generates feeding currents. The durations of both beating modes have log-normal distributions. Without prey, A. tonsa only samples the environment at low frequency. Upon introduction of non-toxic food, it increases its sampling time moderately and the grazing period substantially. On mono algal diets for either of the toxic dinoflagellates, sampling time fraction is high but the grazing is very limited. A. tonsa demonstrates aversion to both toxic algal species. In mixtures of S. major and the neurotoxin producing K. brevis, sampling and grazing diminish rapidly, presumably due to neurological effects of consuming brevetoxins while trying to feed on S. major. In contrast, on mixtures of cytotoxin producing K. veneficum, both behavioral modes persist, indicating that intake of karlotoxins does not immediately inhibit the copepod’s grazing behavior. These findings add critical insight into how these algal toxins may influence the copepod’s feeding behavior, and suggest how some harmful algal species may alter top-down control exerted by grazers like copepods. PMID:22629336

Algal toxins alter copepod feeding behavior.

Directory of Open Access Journals (Sweden)

Jiarong Hong

Full Text Available Using digital holographic cinematography, we quantify and compare the feeding behavior of free-swimming copepods, Acartia tonsa, on nutritional prey (Storeatula major to that occurring during exposure to toxic and non-toxic strains of Karenia brevis and Karlodinium veneficum. These two harmful algal species produce polyketide toxins with different modes of action and potency. We distinguish between two different beating modes of the copepod's feeding appendages-a "sampling beating" that has short durations (<100 ms and involves little fluid entrainment and a longer duration "grazing beating" that persists up to 1200 ms and generates feeding currents. The durations of both beating modes have log-normal distributions. Without prey, A. tonsa only samples the environment at low frequency. Upon introduction of non-toxic food, it increases its sampling time moderately and the grazing period substantially. On mono algal diets for either of the toxic dinoflagellates, sampling time fraction is high but the grazing is very limited. A. tonsa demonstrates aversion to both toxic algal species. In mixtures of S. major and the neurotoxin producing K. brevis, sampling and grazing diminish rapidly, presumably due to neurological effects of consuming brevetoxins while trying to feed on S. major. In contrast, on mixtures of cytotoxin producing K. veneficum, both behavioral modes persist, indicating that intake of karlotoxins does not immediately inhibit the copepod's grazing behavior. These findings add critical insight into how these algal toxins may influence the copepod's feeding behavior, and suggest how some harmful algal species may alter top-down control exerted by grazers like copepods.

Toxins of filamentous fungi.

Science.gov (United States)

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

Effect of toxin-g from Tityus serrulatus scorpion venom on gastric emptying in rats

Directory of Open Access Journals (Sweden)

F. Bucaretchi

1999-04-01

Full Text Available The effect of toxin-g from Tityus serrulatus scorpion venom on the gastric emptying of liquids was studied in 176 young adult male Wistar rats (2-3 months of age divided into subgroups of 8 animals each. Toxin-g was injected iv at doses of 25, 37.5, 50 or 100 µg/kg and the effect on gastric emptying was assessed 30 min and 8 h later. A time-course study was also performed by injecting 50 µg of toxin-g /kg and measuring the effect on gastric emptying at times 0.25, 0.5, 1, 2, 4, 8, 24 and 48 h post-venom. Each envenomed animal was paired with its saline control and all received a saline test meal solution containing phenol red (60 µg/ml as a marker. Ten minutes after administering the test meal by gavage the animals were sacrificed and gastric retention was determined by measuring the residual marker concentration of the test meal. A significant delay in gastric emptying, at 30 min and 8 h post-venom, was observed only after 50 and 100 µg of toxin-g /kg compared to control values. The responses to these two doses were significantly different after 8 h post-venom. Toxin-g (50 µg/kg significantly delayed the gastric emptying of liquids at all times studied, with a peak response at 4 h after toxin administration compared to control values. These results indicate that the iv injection of toxin-g may induce a rapid, intense and sustained inhibition of gastric emptying 0.25 to 48 h after envenomation.

Adipogenic human adenovirus Ad-36 induces commitment, differentiation, and lipid accumulation in human adipose-derived stem cells

DEFF Research Database (Denmark)

Pasarica, Magdalena; Mashtalir, Nazar; McAllister, Emily J

2008-01-01

Human adenovirus Ad-36 is causatively and correlatively linked with animal and human obesity, respectively. Ad-36 enhances differentiation of rodent preadipocytes, but its effect on adipogenesis in humans is unknown. To indirectly assess the role of Ad-36-induced adipogenesis in human obesity......, the effect of the virus on commitment, differentiation, and lipid accumulation was investigated in vitro in primary human adipose-derived stem/stromal cells (hASC). Ad-36 infected hASC in a time- and dose-dependent manner. Even in the presence of osteogenic media, Ad-36-infected hASC showed significantly...... greater lipid accumulation, suggestive of their commitment to the adipocyte lineage. Even in the absence of adipogenic inducers, Ad-36 significantly increased hASC differentiation, as indicated by a time-dependent expression of genes within the adipogenic cascade-CCAAT/Enhancer binding protein...

Simplified dynamic analysis to evaluate liquefaction-induced lateral deformation of earth slopes: a computational fluid dynamics approach

Science.gov (United States)

Jafarian, Yaser; Ghorbani, Ali; Ahmadi, Omid

2014-09-01

Lateral deformation of liquefiable soil is a cause of much damage during earthquakes, reportedly more than other forms of liquefaction-induced ground failures. Researchers have presented studies in which the liquefied soil is considered as viscous fluid. In this manner, the liquefied soil behaves as non-Newtonian fluid, whose viscosity decreases as the shear strain rate increases. The current study incorporates computational fluid dynamics to propose a simplified dynamic analysis for the liquefaction-induced lateral deformation of earth slopes. The numerical procedure involves a quasi-linear elastic model for small to moderate strains and a Bingham fluid model for large strain states during liquefaction. An iterative procedure is considered to estimate the strain-compatible shear stiffness of soil. The post-liquefaction residual strength of soil is considered as the initial Bingham viscosity. Performance of the numerical procedure is examined by using the results of centrifuge model and shaking table tests together with some field observations of lateral ground deformation. The results demonstrate that the proposed procedure predicts the time history of lateral ground deformation with a reasonable degree of precision.

Accumulation of pathogenic ΔmtDNA induced deafness but not diabetic phenotypes in mito-mice

International Nuclear Information System (INIS)

Nakada, Kazuto; Sato, Akitsugu; Sone, Hideyuki; Kasahara, Atsuko; Ikeda, Katsuhisa; Kagawa, Yasuo; Yonekawa, Hiromichi; Hayashi, Jun-Ichi

2004-01-01

Mito-mice carrying various proportions of deletion mutant mtDNA (ΔmtDNA) were generated by introduction of the ΔmtDNA from cultured cells into fertilized eggs of C57BL/6J (B6) strain mice. Great advantages of mito-mice are that they share exactly the same nuclear-genome background, and that their genetic variations are restricted to proportions of pathogenic ΔmtDNA. Since accumulation of ΔmtDNA to more than 75% induced respiration defects, the disease phenotypes observed exclusively in mito-mice carrying more than 75% ΔmtDNA should be due to accumulated ΔmtDNA. In this study, we focused on the expressions of hearing loss and diabetic phenotypes, since these common age-associated abnormalities have sometimes been reported to be inherited maternally and to be associated with pathogenic mutant mtDNAs. The results showed that accumulation of exogenously introduced ΔmtDNA was responsible for hearing loss, but not for expression of diabetic phenotypes in mito-mice

Patterns of gravity induced aggregate migration during casting of fluid concretes

Energy Technology Data Exchange (ETDEWEB)

Spangenberg, J. [Department of Mechanical Engineering, Technical University of Denmark (DTU) (Denmark); Roussel, N., E-mail: Nicolas.roussel@lcpc.fr [Universite Paris Est, Laboratoire Central des Ponts et Chaussees (LCPC) (France); Hattel, J.H. [Department of Mechanical Engineering, Technical University of Denmark (DTU) (Denmark); Sarmiento, E.V.; Zirgulis, G. [Department of Structural Engineering, Norwegian University of Science and Technology (NTNU) (Norway); Geiker, M.R. [Department of Structural Engineering, Norwegian University of Science and Technology (NTNU) (Norway); Department of Civil Engineering, Technical University of Denmark (DTU) (Denmark)

2012-12-15

In this paper, aggregate migration patterns during fluid concrete castings are studied through experiments, dimensionless approach and numerical modeling. The experimental results obtained on two beams show that gravity induced migration is primarily affecting the coarsest aggregates resulting in a decrease of coarse aggregates volume fraction with the horizontal distance from the pouring point and in a puzzling vertical multi-layer structure. The origin of this multi layer structure is discussed and analyzed with the help of numerical simulations of free surface flow. Our results suggest that it finds its origin in the non Newtonian nature of fresh concrete and that increasing casting rate shall decrease the magnitude of gravity induced particle migration.

Patterns of gravity induced aggregate migration during casting of fluid concretes

International Nuclear Information System (INIS)

Spangenberg, J.; Roussel, N.; Hattel, J.H.; Sarmiento, E.V.; Zirgulis, G.; Geiker, M.R.

2012-01-01

In this paper, aggregate migration patterns during fluid concrete castings are studied through experiments, dimensionless approach and numerical modeling. The experimental results obtained on two beams show that gravity induced migration is primarily affecting the coarsest aggregates resulting in a decrease of coarse aggregates volume fraction with the horizontal distance from the pouring point and in a puzzling vertical multi-layer structure. The origin of this multi layer structure is discussed and analyzed with the help of numerical simulations of free surface flow. Our results suggest that it finds its origin in the non Newtonian nature of fresh concrete and that increasing casting rate shall decrease the magnitude of gravity induced particle migration.

Toxin-Antitoxin Battle in Bacteria

DEFF Research Database (Denmark)

Cataudella, Ilaria

This PhD thesis consists of three research projects revolving around the common thread of investigation of the properties and biological functions of Toxin-Antitoxin loci. Toxin-Antitoxin (TA) loci are transcriptionally regulated via an auto-inhibition mechanism called conditional cooperativity, ...

Three-dimensional vortex-induced vibrations of supported pipes conveying fluid based on wake oscillator models

Science.gov (United States)

Wang, L.; Jiang, T. L.; Dai, H. L.; Ni, Q.

2018-05-01

The present study develops a new three-dimensional nonlinear model for investigating vortex-induced vibrations (VIV) of flexible pipes conveying internal fluid flow. The unsteady hydrodynamic forces associated with the wake dynamics are modeled by two distributed van der Pol wake oscillators. In particular, the nonlinear partial differential equations of motion of the pipe and the wake are derived, taking into account the coupling between the structure and the fluid. The nonlinear equations of motion for the coupled system are then discretized by means of the Galerkin technique, resulting in a high-dimensional reduced-order model of the system. It is shown that the natural frequencies for in-plane and out-of-plane motions of the pipe may be different at high internal flow velocities beyond the threshold of buckling instability. The orientation angle of the postbuckling configuration is time-varying due to the disturbance of hydrodynamic forces, thus yielding sometimes unexpected results. For a buckled pipe with relatively low cross-flow velocity, interestingly, examining the nonlinear dynamics of the pipe indicates that the combined effects of the cross-flow-induced resonance of the in-plane first mode and the internal-flow-induced buckling on the IL and CF oscillation amplitudes may be significant. For higher cross-flow velocities, however, the effect of internal fluid flow on the nonlinear VIV responses of the pipe is not pronounced.

Water flow patterns induced by bridge oscillation of magnetic fluid between two permanent magnets subjected to alternating magnetic field

International Nuclear Information System (INIS)

Sudo, Seiichi; Yamamoto, Kazuki; Ishimoto, Yukitaka; Nix, Stephanie

2017-01-01

This paper describes the characteristics of water flow induced by the bridge oscillation of magnetic fluid between two permanent magnets subject to an external alternating magnetic field. The magnetic fluid bridge is formed in the space between a pair of identical coaxial cylindrical permanent magnets submerged in water. The direction of alternating magnetic field is parallel /antiparallel to the magnetic field produced by two permanent magnets. The magnetic fluid bridge responds to the external alternating magnetic field with harmonic oscillation. The oscillation of magnetic fluid bridge generates water flow around the bridge. Water flow is visualized using a thin milk film at the container bottom. Water flows are observed with a high-speed video camera analysis system. The experimental results show that the flow pattern induced by the bridge oscillation depends on the Keulegan–Carpenter number.

Water flow patterns induced by bridge oscillation of magnetic fluid between two permanent magnets subjected to alternating magnetic field

Energy Technology Data Exchange (ETDEWEB)

Sudo, Seiichi, E-mail: sudo@akita-pu.ac.jp [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Yamamoto, Kazuki [Graduate School of Engineering, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Ishimoto, Yukitaka; Nix, Stephanie [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan)

2017-06-01

This paper describes the characteristics of water flow induced by the bridge oscillation of magnetic fluid between two permanent magnets subject to an external alternating magnetic field. The magnetic fluid bridge is formed in the space between a pair of identical coaxial cylindrical permanent magnets submerged in water. The direction of alternating magnetic field is parallel /antiparallel to the magnetic field produced by two permanent magnets. The magnetic fluid bridge responds to the external alternating magnetic field with harmonic oscillation. The oscillation of magnetic fluid bridge generates water flow around the bridge. Water flow is visualized using a thin milk film at the container bottom. Water flows are observed with a high-speed video camera analysis system. The experimental results show that the flow pattern induced by the bridge oscillation depends on the Keulegan–Carpenter number.

Chronic Insulin Exposure Induces ER Stress and Lipid Body Accumulation in Mast Cells at the Expense of Their Secretory Degranulation Response.

Directory of Open Access Journals (Sweden)

William E Greineisen

Full Text Available Lipid bodies (LB are reservoirs of precursors to inflammatory lipid mediators in immunocytes, including mast cells. LB numbers are dynamic, increasing dramatically under conditions of immunological challenge. We have previously shown in vitro that insulin-influenced lipogenic pathways induce LB biogenesis in mast cells, with their numbers attaining steatosis-like levels. Here, we demonstrate that in vivo hyperinsulinemia resulting from high fat diet is associated with LB accumulation in murine mast cells and basophils. We characterize the lipidome of purified insulin-induced LB, and the shifts in the whole cell lipid landscape in LB that are associated with their accumulation, in both model (RBL2H3 and primary mast cells. Lipidomic analysis suggests a gain of function associated with LB accumulation, in terms of elevated levels of eicosanoid precursors that translate to enhanced antigen-induced LTC4 release. Loss-of-function in terms of a suppressed degranulation response was also associated with LB accumulation, as were ER reprogramming and ER stress, analogous to observations in the obese hepatocyte and adipocyte. Taken together, these data suggest that chronic insulin elevation drives mast cell LB enrichment in vitro and in vivo, with associated effects on the cellular lipidome, ER status and pro-inflammatory responses.

Laser induced ablatively driven interfacial nonlinear fluid instabilities in multilayer targets

International Nuclear Information System (INIS)

Manoranjan Khan; Gupta, M.R.; Mandal, L.K.; Roy, S.; Banerjee, R.

2010-01-01

Complete text of publication follows. High power laser driven shock waves in condensed matter have important application for studying equation of state (EOS) and high pressure physics. This is an important phenomenon in fuel compression for Inertial Confinement Fusion (ICF) experiments where multilayer targets of differing shock impedance are interacted by laser induced shocks. The interface between the two fluid becomes unstable when driven by the impulsive force (Richtmyer-Meshkov) due to such a shock wave or a continuously acting force e.g., gravity (Rayleigh-Taylor). In the nonlinear stage, the fluid interface is found to develop structures having finger-like shapes. The structures resemble a bubble (spike) accordingly as a lighter (heavier) fluid pushes in a heavier (lighter) fluid. These effects need to be mitigated for efficient compression in ICF experiment. We have studied the effect of density variation on R-T and R-M instability on the temporal development of nonlinear two fluid interfacial structures like bubble and spike. It is shown that the velocity of bubble or spike decreases leading to stabilization if the density of the fluids leads to lowering of the Atwood number. The Atwood number A = ρ a -ρ b / ρ a +ρ b changes to A* = ρ a *ρ b */ ρ a *ρ b * where ρ* m = ρ m (1-1/γ m ), m = [a,b], assuming ρ a > ρ b . It has been seen that the stabilization or destabilization (depending on the algebraic sign of the gradient) will be proportional to the pressure p 0 at the interface. The set of equation describing the dynamics of the bubbles and spikes in presence of fluid density variation are not analytically integrable in closed form. All the results are derived by numerical methods and are represented and interpreted. Analytical calculations are performed (not presented here) to modify the dynamical boundary condition between the two fluids and we have finally arrived at the following expression for the asymptotic bubble velocity ν b 2 = 2(r

Bio Warfare and Terrorism: Toxins and Other Mid-Spectrum Agents

National Research Council Canada - National Science Library

Madsen, James M

2005-01-01

... counterparts are still by definition toxins. Related terms include phycotoxins (toxins from algae), mycotoxins (fungal toxins), phytotoxins (plant toxins), and venoms (toxins from animals, especially vertebrates...

PSP toxin levels and plankton community composition and abundance in size-fractionated vertical profiles during spring/summer blooms of the toxic dinoflagellate Alexandrium fundyense in the Gulf of Maine and on Georges Bank, 2007, 2008, and 2010: 2. Plankton community composition and abundance.

Science.gov (United States)

Petitpas, Christian M; Turner, Jefferson T; Deeds, Jonathan R; Keafer, Bruce A; McGillicuddy, Dennis J; Milligan, Peter J; Shue, Vangie; White, Kevin D; Anderson, Donald M

2014-05-01

As part of the Gulf of Maine Toxicity (GOMTOX) project, we determined Alexandrium fundyense abundance, paralytic shellfish poisoning (PSP) toxin levels in various plankton size fractions, and the community composition of potential grazers of A. fundyense in plankton size fractions during blooms of this toxic dinoflagellate in the coastal Gulf of Maine and on Georges Bank in spring and summer of 2007, 2008, and 2010. PSP toxins and A. fundyense cells were found throughout the sampled water column (down to 50 m) in the 20-64 μm size fractions. While PSP toxins were widespread throughout all size classes of the zooplankton grazing community, the majority of the toxin was measured in the 20-64 μm size fraction. A. fundyense cellular toxin content estimated from field samples was significantly higher in the coastal Gulf of Maine than on Georges Bank. Most samples containing PSP toxins in the present study had diverse assemblages of grazers. However, some samples clearly suggested PSP toxin accumulation in several different grazer taxa including tintinnids, heterotrophic dinoflagellates of the genus Protoperidinium , barnacle nauplii, the harpacticoid copepod Microsetella norvegica , the calanoid copepods Calanus finmarchicus and Pseudocalanus spp., the marine cladoceran Evadne nordmanni , and hydroids of the genus Clytia . Thus, a diverse assemblage of zooplankton grazers accumulated PSP toxins through food-web interactions. This raises the question of whether PSP toxins pose a potential human health risk not only from nearshore bivalve shellfish, but also potentially from fish and other upper-level consumers in zooplankton-based pelagic food webs.

Engineering toxins for 21st century therapies.

Science.gov (United States)

Chaddock, John A; Acharya, K Ravi

2011-04-01

'Engineering Toxins for 21st Century Therapies' (9-10 September 2010) was part of the Royal Society International Seminar series held at the Kavli International Centre, UK. Participants were assembled from a range of disciplines (academic, industry, regulatory, public health) to discuss the future potential of toxin-based therapies. The meeting explored how the current structural and mechanistic knowledge of toxins could be used to engineer future toxin-based therapies. To date, significant progress has been made in the design of novel recombinant biologics based on domains of natural toxins, engineered to exhibit advantageous properties. The meeting concluded, firstly that future product development vitally required the appropriate combination of creativity and innovation that can come from the academic, biotechnology and pharma sectors. Second, that continued investigation into understanding the basic science of the toxins and their targets was essential in order to develop new opportunities for the existing products and to create new products with enhanced properties. Finally, it was concluded that the clinical potential for development of novel biologics based on toxin domains was evident. © 2011 The Authors Journal compilation © 2011 FEBS.

Shape memory alloy actuated accumulator for ultra-deepwater oil and gas exploration

Science.gov (United States)

Patil, Devendra; Song, Gangbing

2016-04-01

As offshore oil and gas exploration moves further offshore and into deeper waters to reach hydrocarbon reserves, it is becoming essential for the industry to develop more reliable and efficient hydraulic accumulators to supply pressured hydraulic fluid for various control and actuation operations, such as closing rams of blowout preventers and controlling subsea valves on the seafloor. By utilizing the shape memory effect property of nitinol, which is a type of shape memory alloy (SMA), an innovative SMA actuated hydraulic accumulator prototype has been developed and successfully tested at Smart Materials and Structure Laboratory at the University of Houston. Absence of gas in the developed SMA accumulator prototype makes it immune to hydrostatic head loss caused by water depth and thus reduces the number of accumulators required in deep water operations. Experiments with a feedback control have demonstrated that the proposed SMA actuated accumulator can provide precisely regulated pressurized fluids. Furthermore the potential use of ultracapacitors along with an embedded system to control the electric power supplied to SMA allows this accumulator to be an autonomous device for deployment. The developed SMA accumulator will make deepwater oil extraction systems more compact and cost effective.

Crystallization of isoelectrically homogeneous cholera toxin

International Nuclear Information System (INIS)

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

1989-01-01

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

Fluid and solid mechanics in a poroelastic network induced by ultrasound.

Science.gov (United States)

Wang, Peng; Olbricht, William L

2011-01-04

We made a theoretical analysis on the fluid and solid mechanics in a poroelastic medium induced by low-power ultrasound. Using a perturbative approach, we were able to linearize the governing equations and obtain analytical solutions. We found that ultrasound could propagate in the medium as a mechanical wave, but would dissipate due to frictional forces between the fluid and the solid phase. The amplitude of the wave depends on the ultrasonic power input. We applied this model to the problem of drug delivery to soft biological tissues by low-power ultrasound and proposed a mechanism for enhanced drug penetration. We have also found the coexistence of two acoustic waves under certain circumstances and pointed out the importance of very accurate experimental determination of the high-frequency properties of brain tissue. Copyright © 2010 Elsevier Ltd. All rights reserved.

Botulinum toxin in trigeminal neuralgia.

Science.gov (United States)

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.

NetB, a new toxin that is associated with avian necrotic enteritis caused by Clostridium perfringens.

Directory of Open Access Journals (Sweden)

Anthony L Keyburn

2008-02-01

Full Text Available For over 30 years a phospholipase C enzyme called alpha-toxin was thought to be the key virulence factor in necrotic enteritis caused by Clostridium perfringens. However, using a gene knockout mutant we have recently shown that alpha-toxin is not essential for pathogenesis. We have now discovered a key virulence determinant. A novel toxin (NetB was identified in a C. perfringens strain isolated from a chicken suffering from necrotic enteritis (NE. The toxin displayed limited amino acid sequence similarity to several pore forming toxins including beta-toxin from C. perfringens (38% identity and alpha-toxin from Staphylococcus aureus (31% identity. NetB was only identified in C. perfringens type A strains isolated from chickens suffering NE. Both purified native NetB and recombinant NetB displayed cytotoxic activity against the chicken leghorn male hepatoma cell line LMH; inducing cell rounding and lysis. To determine the role of NetB in NE a netB mutant of a virulent C. perfringens chicken isolate was constructed by homologous recombination, and its virulence assessed in a chicken disease model. The netB mutant was unable to cause disease whereas the wild-type parent strain and the netB mutant complemented with a wild-type netB gene caused significant levels of NE. These data show unequivocally that in this isolate a functional NetB toxin is critical for the ability of C. perfringens to cause NE in chickens. This novel toxin is the first definitive virulence factor to be identified in avian C. perfringens strains capable of causing NE. Furthermore, the netB mutant is the first rationally attenuated strain obtained in an NE-causing isolate of C. perfringens; as such it has considerable vaccine potential.

Entry of Shiga toxin into cells

DEFF Research Database (Denmark)

Sandvig, Kirsten; van Deurs, Bo

1994-01-01

Cellebiologi, Shiga toxin, receptors, glycolipids, endocytosis, trans-Golgi network, endoplasmic reticulum, retrograde transport......Cellebiologi, Shiga toxin, receptors, glycolipids, endocytosis, trans-Golgi network, endoplasmic reticulum, retrograde transport...

Botulinum Toxin: Pharmacology and Therapeutic Roles in Pain States.

Science.gov (United States)

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

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Christopher Bachran

2016-07-01

Full Text Available 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.

Tumor Targeting and Drug Delivery by Anthrax Toxin.

Science.gov (United States)

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.

Structural studies of the toxin-antitoxin proteins RelE and RelB from E. coli

DEFF Research Database (Denmark)

Andersen, Kasper Røjkjær; Overgaard, Martin; Gerdes, Kenn

the special tRNA-mRNA mimic, tmRNA [1]. Questions to be addressed Many questions remain to be answered in the bacterial toxin-antitoxin system. The crystal structure of RelBE from Pyrococcus horikoshii OT3 was previously solved at 2.3Å [2]. This structure shows the molecule in an inactive state, but OT3......The bacterial toxin-antitoxin system The relBE operon in E. coli encodes two small proteins: A toxin, RelE (12 kDa) and an antitoxin, RelB (9 kDa). RelE is activated under nutritional stress and is able to inhibit protein synthesis by cleaving the mRNA in the ribosomal A-site. This stress response...... serves to down-regulate metabolism in the cell when growth conditions are limited. RelB is expressed in excess over RelE during balanced growth, and inhibits the toxicity of RelE by forming an extremely stable toxin-antitoxin complex. The activation of RelE is induced when the labile RelB protein...

Loading and Light Degradation Characteristics of B t Toxin on Nano goethite: A Potential Material for Controlling the Environmental Risk of B t Toxin

International Nuclear Information System (INIS)

Zhou, X.; She, Ch.; She, Ch.; Liu, H.

2015-01-01

Transgenic B t-modified crops release toxins into soil through root exudate s and upon decomposition of residues. The fate of these toxins in soil has not been yet clearly elucidated. Nano goethite was found to have a different influence on the lifetime and identicalness activity of B t toxin. The aim of this study was to elucidate the adsorption characteristics of B t toxin on nano goethite and its activity changes before and after adsorption. The adsorption of toxin on nano goethite reached equilibrium within 5 h, and the adsorption isotherm of B t toxin on nano goethite conformed to the Langmuir equation (). In the range of ph from 6.0 to 8.0, larger adsorption occurred at lower ph value. The toxin adsorption decreased with the temperature between 10 and 50 degree. The results of Ftir, XRD, and SEM indicated that toxin did not influence the structure of nano goethite and the adsorption of toxin only on the surface of nano goethite. The LC_5_0 value for bound toxin was higher than that of free toxin, and the nano goethite greatly accelerated the degradation of toxin by ultraviolet irradiation. The above results suggested that nano goethite is a potential material for controlling the environmental risk of toxin released by Bt transgenic plants

Trigeminal ganglion neurons of mice show intracellular chloride accumulation and chloride-dependent amplification of capsaicin-induced responses.

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Nicole Schöbel

Full Text Available Intracellular Cl(- concentrations ([Cl(-](i of sensory neurons regulate signal transmission and signal amplification. In dorsal root ganglion (DRG and olfactory sensory neurons (OSNs, Cl(- is accumulated by the Na(+-K(+-2Cl(- cotransporter 1 (NKCC1, resulting in a [Cl(-](i above electrochemical equilibrium and a depolarizing Cl(- efflux upon Cl(- channel opening. Here, we investigate the [Cl(-](i and function of Cl(- in primary sensory neurons of trigeminal ganglia (TG of wild type (WT and NKCC1(-/- mice using pharmacological and imaging approaches, patch-clamping, as well as behavioral testing. The [Cl(-](i of WT TG neurons indicated active NKCC1-dependent Cl(- accumulation. Gamma-aminobutyric acid (GABA(A receptor activation induced a reduction of [Cl(-](i as well as Ca(2+ transients in a corresponding fraction of TG neurons. Ca(2+ transients were sensitive to inhibition of NKCC1 and voltage-gated Ca(2+ channels (VGCCs. Ca(2+ responses induced by capsaicin, a prototypical stimulus of transient receptor potential vanilloid subfamily member-1 (TRPV1 were diminished in NKCC1(-/- TG neurons, but elevated under conditions of a lowered [Cl(-](o suggesting a Cl(--dependent amplification of capsaicin-induced responses. Using next generation sequencing (NGS, we found expression of different Ca(2+-activated Cl(- channels (CaCCs in TGs of mice. Pharmacological inhibition of CaCCs reduced the amplitude of capsaicin-induced responses of TG neurons in Ca(2+ imaging and electrophysiological recordings. In a behavioral paradigm, NKCC1(-/- mice showed less avoidance of the aversive stimulus capsaicin. In summary, our results strongly argue for a Ca(2+-activated Cl(--dependent signal amplification mechanism in TG neurons that requires intracellular Cl(- accumulation by NKCC1 and the activation of CaCCs.

Tx2-6 toxin of the Phoneutria nigriventer spider potentiates rat erectile function☆

Science.gov (United States)

Nunes, K.P.; Costa-Gonçalves, A.; Lanza, L.F.; Cortes, S.F.; Cordeiro, M.N.; Richardson, M.; Pimenta, A.M.C.; Webb, R.C.; Leite, R.; De Lima, M.E.

2011-01-01

The venom of the spider Phoneutria nigriventer contains several toxins that have bioactivity in mammals and insects. Accidents involving humans are characterized by various symptoms including penile erection. Here we investigated the action of Tx2-6, a toxin purified from the P. nigriventer spider venom that causes priapism in rats and mice. Erectile function was evaluated through changes in intracavernosal pressure/mean arterial pressure ratio (ICP/MAP) during electrical stimulation of the major pelvic ganglion (MPG) of normotensive and deoxycorticosterone-acetate (DOCA)-salt hypertensive rats. Nitric oxide (NO) release was detected in cavernosum slices with fluorescent dye (DAF-FM) and confocal microscopy. The effect of Tx2-6 was also characterized after intracavernosal injection of a non-selective nitric oxide synthase (NOS) inhibitor, L-NAME. Subcutaneous or intravenous injection of Tx2-6 potentiated the elevation of ICP/MAP induced by ganglionic stimulation. L-NAME inhibited penile erection and treatment with Tx2-6 was unable to reverse this inhibition. Tx2-6 treatment induced a significant increase of NO release in cavernosum tissue. Attenuated erectile function of DOCA-salt hypertensive rats was fully restored after toxin injection. Tx2-6 enhanced erectile function in normotensive and DOCA-salt hypertensive rats, via the NO pathway. Our studies suggest that Tx2-6 could be important for development of new pharmacological agents for treatment of erectile dysfunction. PMID:18397797

Heat shock-induced accumulation of translation elongation and termination factors precedes assembly of stress granules in S. cerevisiae.

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Tomas Grousl

Full Text Available In response to severe environmental stresses eukaryotic cells shut down translation and accumulate components of the translational machinery in stress granules (SGs. Since they contain mainly mRNA, translation initiation factors and 40S ribosomal subunits, they have been referred to as dominant accumulations of stalled translation preinitiation complexes. Here we present evidence that the robust heat shock-induced SGs of S. cerevisiae also contain translation elongation factors eEF3 (Yef3p and eEF1Bγ2 (Tef4p as well as translation termination factors eRF1 (Sup45p and eRF3 (Sup35p. Despite the presence of the yeast prion protein Sup35 in heat shock-induced SGs, we found out that its prion-like domain is not involved in the SGs assembly. Factors eEF3, eEF1Bγ2 and eRF1 were accumulated and co-localized with Dcp2 foci even upon a milder heat shock at 42°C independently of P-bodies scaffolding proteins. We also show that eEF3 accumulations at 42°C determine sites of the genuine SGs assembly at 46°C. We suggest that identification of translation elongation and termination factors in SGs might help to understand the mechanism of the eIF2α factor phosphorylation-independent repression of translation and SGs assembly.

Refeeding-induced brown adipose tissue glycogen hyper-accumulation in mice is mediated by insulin and catecholamines.

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Christopher M Carmean

Full Text Available Brown adipose tissue (BAT generates heat during adaptive thermogenesis through a combination of oxidative metabolism and uncoupling protein 1-mediated electron transport chain uncoupling, using both free-fatty acids and glucose as substrate. Previous rat-based work in 1942 showed that prolonged partial fasting followed by refeeding led to a dramatic, transient increase in glycogen stores in multiple fat depots. In the present study, the protocol was replicated in male CD1 mice, resulting in a 2000-fold increase in interscapular BAT (IBAT glycogen levels within 4-12 hours (hr of refeeding, with IBAT glycogen stores reaching levels comparable to fed liver glycogen. Lesser effects occurred in white adipose tissues (WAT. Over the next 36 hr, glycogen levels dissipated and histological analysis revealed an over-accumulation of lipid droplets, suggesting a potential metabolic connection between glycogenolysis and lipid synthesis. 24 hr of total starvation followed by refeeding induced a robust and consistent glycogen over-accumulation similar in magnitude and time course to the prolonged partial fast. Experimentation demonstrated that hyperglycemia was not sufficient to drive glycogen accumulation in IBAT, but that elevated circulating insulin was sufficient. Additionally, pharmacological inhibition of catecholamine production reduced refeeding-induced IBAT glycogen storage, providing evidence of a contribution from the central nervous system. These findings highlight IBAT as a tissue that integrates both canonically-anabolic and catabolic stimulation for the promotion of glycogen storage during recovery from caloric deficit. The preservation of this robust response through many generations of animals not subjected to food deprivation suggests that the over-accumulation phenomenon plays a critical role in IBAT physiology.

Refeeding-Induced Brown Adipose Tissue Glycogen Hyper-Accumulation in Mice Is Mediated by Insulin and Catecholamines

Science.gov (United States)

Carmean, Christopher M.; Bobe, Alexandria M.; Yu, Justin C.; Volden, Paul A.; Brady, Matthew J.

2013-01-01