karsch toxin bmk: Topics by WorldWideScience.org

Photolabelling reveals differences between cholera toxin and ricin toxin insertion mechanisms

Clostridium perfringens produces numerous toxins, which are responsible for severe diseases in man and animals. Delta toxin is one of the three hemolysins released by a number of C....Full Text Available

Some properties of beta-toxin produced by Clostridium perfringens type C.

... carbon 14 cholera gels labelling membranes molecules proteins receptors

1982-07-28

Multiple Epoxide Hydrolases in Alternaria alternata f. sp. lycopersici and Their Relationship to Medium Composition and Host-Specific Toxin Production

Purified beta-toxin from Clostridium perfringens type C was found to be a single polypeptide chain protein with a molecular weight of approximately 30,000. The toxin was heat labile, with 75% of its...Full Text Available

1978-08-01

Alpha-toxin of Staphylococcus aureus.

The production of Alternaria alternata f. sp. lycopersici host-specific toxins (AAL toxins) and epoxide hydrolase (EH) activity were studied during the growth of this...Full Text Available

1999-06-01

Steady-state levels of G-protein beta-subunit expression are regulated by treatment of cells with bacterial toxins

Alpha-toxin, the major cytotoxic agent elaborated by Staphylococcus aureus, was the first bacterial exotoxin to be identified as a pore former. The protein is secreted as a single-chain, water-soluble...Full Text Available

1991-12-01

Cholera toxin entry into pig enterocytes occurs via a lipid raft- and clathrin-dependent mechanism

Cultures of 3T3-L1 cells were incubated with either 10 ng/ml cholera toxin or 10 ng/ml pertussis toxin from 4 days prior to the initiation of differentiation and throughout the subsequent incubation. Toxin concentrations were sufficient to completely prevent the labelling of alpha-subunits with ["3"2P]NAD"+ and pertussis toxin and to prevent by more than 90% the labelling with ["3"2P]NAD"+ and cholera toxin in membranes prepared from these cells. Neither toxin prevented the differentiation to the adipocyte phenotype. Neither toxin prevented the increases in the relative amounts of G-proteins which occur upon differentiation. Both toxins dramatically decreased the amount of beta-subunits. As measured by quantitative immunoblotting with antisera specific for both the 35 kDa and 36 kDa beta-subunits, levels of beta-subunit ...

1987-06-07

DEFF Research Database (Denmark)

Udgivelsesdato: 2005-Jan-25

2005-01-01

Shiga Toxin Subtypes Display Dramatic Differences in Potency ?

Selection and characterization of ricin toxin A-chain mutations in Saccharomyces cerevisiae.

Purified Shiga toxin (Stx) alone is capable of producing systemic complications, including hemolytic-uremic syndrome (HUS), in animal models of disease. Stx includes two major antigenic forms (Stx1...Full Text Available

2011-03-01

Isolation and characterization of a novel lepidopteran-selective toxin from the venom of South Indian red scorpion, Mesobuthus tamulus

A DNA sequence encoding the A chain of ricin toxin (RTA) from the castor bean plant, Ricinus communis, was placed under GAL1 promoter control and transformed into Saccharomyces cerevisiae. Induction...Full Text Available

1989-02-01

Intraprostatic injection of botulinum toxin type- A relieves bladder outlet obstruction in human and induces prostate apoptosis in dogs

BackgroundScorpion venom contains insect and mammal selective toxins. We investigated the venom of the South Indian red scorpion, Mesobuthus tamulus for the purpose...Full Text Available

Identification and characterization of Aedes aegypti aminopeptidase N as a putative receptor of Bacillus thuringiensis Cry11A toxin

BackgroundWith the increasing interest with botulinum toxin – A (BTX-A) application in the lower urinary tract, we investigated the BTX-A effects on the canine prostate and...Full Text Available

Detection and enumeration of toxin-producing Pasteurella multocida with a colony-blot assay.

Bacillus thuringiensis subsp. israelensis, which is used worldwide to control Aedes aegypti larvae, produces Cry11Aa and other toxins during...Full Text Available

2009-10-01

Detection and Toxin Typing of Clostridium perfringens in Formalin-Fixed, Paraffin-Embedded Tissue Samples by PCR?

Colonies of toxin-producing Pasteurella multocida were detected with peroxidase-labeled monoclonal antibodies by a membrane assay. Examination of the specificity of the assay with 29 P. multocida cultures...Full Text Available

1991-07-01

Concurrent Exposure of Bottlenose Dolphins (Tursiops truncatus) to Multiple Algal Toxins in Sarasota Bay, Florida, USA

Since current microbiology methods are not suitable to detect Clostridium perfringens in formalin-fixed, paraffin-embedded tissue samples, we developed a PCR assay to detect toxin-encoding...Full Text Available

2009-03-01

Characterization of Toxin Plasmids in Clostridium perfringens Type C Isolates?

Sentinel species such as bottlenose dolphins (Tursiops truncatus) can be impacted by large-scale mortality events due to exposure to marine algal toxins. In the Sarasota Bay region...Full Text Available

Blarina toxin, a mammalian lethal venom from the short-tailed shrew Blarina brevicauda: Isolation and characterization

Clostridium perfringens type C isolates cause enteritis necroticans in humans or necrotizing enteritis and enterotoxemia in domestic animals. Type C isolates always produce alpha toxin...Full Text Available

2010-11-01

Binary Bacterial Toxins: Biochemistry, Biology, and Applications of Common Clostridium and Bacillus Proteins

Venomous mammals are rare, and their venoms have not been characterized. We have purified and characterized the blarina toxin (BLTX), a lethal mammalian venom with a tissue kallikrein-like activity...Full Text Available

2004-05-18

Cholera toxin binding sites in yeast triggers biochemical pathway

Certain pathogenic species of Bacillus and Clostridium have developed unique methods for intoxicating cells that employ the classic enzymatic “A-B” paradigm for protein toxins. The binary...Full Text Available

2004-09-01

Effects of pseudomonas toxin A, diphtheria toxin, and cholera toxin on electrical characteristics of turtle bladder.

... e Biologia Molecular (SBBq), Sao Paulo, SP (Brazil) 217 p. APPLIED LIFE

1998-05-23

1 2 3 4 5

A comparison of hepatic in vitro metabolism of T-2 toxin in rats, pigs, chickens, and carp

Rapidly developing changes in the short-circuiting current (Isc), conductance (G), and potential (PD) of turtle bladders in Na-rich or Na-free media are seen after the mucosal addition, at 10 nM, of...Full Text Available

1979-07-01

British Library Electronic Table of Contents (United Kingdom)

T-2 toxin, a highly toxic member of the type-A trichothecenes, is produced by various Fusarium moulds that can potentially affect human health. It is strongly cytotoxic for human hematopoietic progenitors. Alimentary toxic aleukia (ATA), a disease typically associated with human, is primarily induced by T-2 toxin. A comparison of the metabolism of T-2 toxin incubated with hepatocytes of rats, piglets, chickens, and the hepatic subcellular fractions (microsomes and cytosol) of piglets, chickens, rats, and carp (common carp and grass carp) was carried out. The activities of the recombinant pig CYP3A29 on the transformation of T-2 and HT-2 toxins were preliminary studied. Metabolites were identified by novel LC/MS-IT-TOF. Qualitative similarities and differences across the species were observ...

2011-01-01

Spatial Relationships between Drug Binding Sites on the ...

Source and profile of paralytic shellfish poisoning toxins in shellfish in Daya Bay, South China Sea

... determination of the molar extinction coefficients, e, were measured by the Lowry method with native a-toxin as a standard. Binding Kinetics. ...

1987-10-15

British Library Electronic Table of Contents (United Kingdom)

Changes in cell density and cyst flux of Alexandrium tamarense, paralytic shellfish poisoning (PSP) toxin contents in shellfishes, and environmental parameters were measured in two stations in Daya Bay, South China Sea from March 2005 to July 2006. Vegetative cells of A. tamarense occurred sporadically; however, they presented abundantly during the winter months. Meanwhile, cyst flux reached its maximum level just following the peak abundance of motile cells. The PSP contents in shellfish were generally low, but higher in winter with the maximum of 14,015 @mg STX equiv./kg. The majority of toxins were found in digestive glands, with a maximum of 66,227 @mg STX equiv./kg. There were significant positive relationships between toxin level and vegetative cell density and cyst flux. This indica...

2011-01-01

Phylogenetic Characterization of Virulence and Resistance Phenotypes of Pseudomonas syringae

Helminthosporium maydis T toxin decreased calcium transport into mitochondria of susceptible corn

Individual strains of the plant pathogenic bacterium Pseudomonas syringae vary in their ability to produce toxins, nucleate ice, and resist antimicrobial compounds. These phenotypes...Full Text Available

2005-09-01

Cholera toxin can catalyze ADP-ribosylation of cytoskeletal proteins

The effects of purified Helminthosporium maydis T (HmT) toxin on active Ca/sup 2 +/ transport into isolated mitochondria and microsomal vesicles were compared for a susceptible (T) and a resistant (N) strain of corn (Zea mays). ATP, malate, NADH, or succinate could drive /sup 45/Ca/sup 2 +/ transport into mitochondria of corn roots. Ca/sup 2 +/ uptake was dependent on the proton electrochemical gradient generated by the redox substrates or the reversible ATP synthetase, as oligomycin inhibited ATP-driven CA/sup 2 +/ uptake while KCN inhibited transport driven by the redox substrates. Purified native HmT toxin completely inhibited Ca/sup 2 +/ transport into T mitochondria at 5 to 10 nanograms per milliliter while transport into N mitochondria was decreased slightly by 100 nanograms per milliliter toxin. Malate-driven Ca/sup 2 +/ transport in T mitochondria was frequently more inhibited by 5 nanograms per milliliter ...

1984-04-01

Bioengineered bugs expressing oligosaccharide receptor mimics

Cholera toxin catalyzes transfer of radiolabel from ["3"2P]NAD"+ to several peptides in particulate preparations of human foreskin fibroblasts. Resolution of these peptides by two-dimensional gel electrophoresis allowed identification of two peptides of M/sub r/ = 42,000 and 52,000 as peptide subunits of a regulatory component of adenylate cyclase. The radiolabeling of another group of peptides (M/sub r/ = 50,000 to 65,000) suggested that cholera toxin could catalyze ADP-ribosylation of cytoskeletal proteins. This suggestion was confirmed by showing that incubation with cholera toxin and ["3"2P]NAD"+ caused radiolabeling of purified microtubule and intermediate filament proteins.

1981-01-01

Unique Bell-shaped Voltage-dependent Modulation of Na⁺ Channel Gating by Novel Insect-selective Toxins from the Spider Agelena orientalis*

Many microbial pathogens recognize oligosaccharides displayed on the surface of host cells as receptors for toxins and adhesins. These ligand-receptor interactions are critical for disease pathogenesis,...Full Text Available

2010-05-01

Dissecting toxin immunity in virus-infected killer yeast uncovers an intrinsic strategy of self-protection

Spider venoms provide a highly valuable source of peptide toxins that act on a wide diversity of membrane-bound receptors and ion channels. In this work, we report isolation, biochemical analysis, and...Full Text Available

2010-06-11

Detection of Shiga Toxin-Producing Escherichia coli Serotypes O26:H11, O103:H2, O111:H8, O145:H28, and O157:H7 in Raw-Milk Cheeses by Using Multiplex Real-Time PCR ?

Toxin-secreting “killer” yeasts were initially identified >40 years ago in Saccharomyces cerevisiae strains infected with a double-stranded RNA “killer”...Full Text Available

2006-03-07

T-2 mycotoxin inhibits mitochondrial protein synthesis

Shiga toxin (Stx)-producing Escherichia coli (STEC) strains are a diverse group of food-borne pathogens with various levels of virulence for humans. In this study, we describe the use...Full Text Available

2011-03-01

Non-toxigenic Clostridium sordellii: Clinical and microbiological features of a case of cholangitis-associated bacteremia

The authors investigated the effect of T-2 toxin on rat liver mitochondrial protein synthesis. Isolated rat liver mitochondria were supplemented with an S-100 supernatant from rat liver and an external ATP-generating system. An in-vitro assay employing cycloheximide, and inhibitor of cytoplasmic protein synthesis, and chloramphenicol, and inhibitor of mitochondrial protein synthesis, to distinguish mitochondrial protein synthesis from the cytoplasmic process. Amino acid incorporation into mitochondria was dependent on the concentration of mitochondria and was inhibited by chloramphenicol. The rate of uptake of tritium leucine into mitochondrial protein was unaffected by the addition of T-2 toxin and was not a rate-limiting step in incorporation. However, 0.02 micrograms/ml of T-2 toxin decreased the rate of protein synthesis inhibition correlated with the amount of T-2 toxin taken up by the ...

1988-01-01

British Library Electronic Table of Contents (United Kingdom)

Toxigenic Clostridium sordellii strains are increasingly recognized to cause highly lethal infections in humans that are typified by a toxic shock syndrome (TSS). Two glucosylating toxins, lethal toxin (TcsL) and hemorrhagic toxin (TcsH) are believed to be important in the pathogenesis of TSS. While non-toxigenic strains of C. sordellii demonstrate reduced cytotoxicity in vitro and lower virulence in animal models of infection, there are few data regarding their behavior in humans. Here we report a non-TSS C. sordellii infection in the context of a polymicrobial bacterial cholangitis. The C. sordellii strain associated with this infection did not carry either the TcsL-encoding tcsL gene or the tcsH gene for TcsH. In addition, the strain was neither cytotoxic in vitro nor lethal in a murine...

2011-01-01

Vibrio cholerae Hemagglutinin/Protease Inactivates CTX?

Tarantula Huwentoxin-IV Inhibits Neuronal Sodium Channels by Binding to Receptor Site 4 and Trapping the Domain II Voltage Sensor in the Closed Configuration*S?

Pathogenic strains of Vibrio cholerae are lysogens of the filamentous phage CTXφ, which carries the genes for cholera toxin (ctxAB). We found that the titers...Full Text Available

1998-09-01

Pore-forming toxins trigger shedding of receptors for interleukin 6 and lipopolysaccharide.

Peptide toxins with high affinity, divergent pharmacological functions, and isoform-specific selectivity are powerful tools for investigating the structure-function relationships of voltage-gated...Full Text Available

2008-10-03

Partial Purification and Characterization of Biological Effects of a Lipid Toxin Produced by Mycobacterium ulcerans

Cleavage of membrane-associated proteins with the release of biologically active macromolecules is an emerging theme in biology. However, little is known about the nature and regulation of the involved...Full Text Available

1996-07-23

Novel Analogs and Stereoisomers of the Marine Toxin Neodysiherbaine with Specificity for Kainate Receptors

Organisms in the genus Mycobacterium cause a variety of human diseases. One member of the genus, M. ulcerans, causes a necrotizing skin disease called Buruli ulcer....Full Text Available

1998-02-01

Mosquitocidal activity of the CryIC delta-endotoxin from Bacillus thuringiensis subsp. aizawai.

Antagonists for kainate receptors (KARs), a family of glutamate-gated ion channels, are efficacious in a number of animal models of neuropathologies, including epilepsy, migraine pain, and anxiety....Full Text Available

2008-02-01

INTRAVITREAL HUMAN IMMUNE GLOBULIN IN A RABBIT MODEL OF STAPHYLOCOCCUS AUREUS TOXIN-MEDIATED ENDOPHTHALMITIS: A POTENTIAL ADJUNCT IN THE TREATMENT OF ENDOPHTHALMITIS

The cloned 135-kDa CryIC delta-endotoxin from Bacillus thuringiensis is a lepidopteran-active toxin, displaying high activity in vivo against Spodoptera litoralis and Spodoptera frugiperda larvae and...Full Text Available

1996-02-01

Effects of Naja nivea venom on nerve, cardiac and skeletal muscle activity of the frog

ABSTRACTObjectivesTo test the feasibility of human immune globulin (IG, Gamimune N, 10%) as a new treatment for endophthalmitis, the ocular tolerance, distribution,...Full Text Available

2004-12-01

1 2 3 4 5

Cloning and expression of recombinant, functional ricin B chain.

1. The effects of 1 mg/ml whole Naja nivea (Cape cobra) venom, and of three different toxins isolated from it, on spinal reflex excitability and cardiac and skeletal muscle activity...Full Text Available

1973-03-01

Ab binding alters gene expression in Cryptococcus neoformans and directly modulates fungal metabolism

The cDNA encoding the B chain of the plant toxin ricin has been cloned and expressed in monkey kidney COS-M6 cells. The recombinant B chain was detected by labeling the transfected cells with [35S]methionine...Full Text Available

1987-08-01

A Bacillus thuringiensis isolation method utilizing a novel stain, low selection and high throughput produced atypical results

Abs facilitate humoral immunity via the classical mechanisms of opsonization, complement activation, Ab-dependent cellular cytotoxicity, and toxin/viral neutralization. There is also evidence that some...Full Text Available

2010-04-01

Isolation and amino acid sequence of a short-chain neurotoxin from an Australian elapid snake, Pseudechis australis.

BackgroundBacillus thuringiensis is a bacterium known for producing protein crystals with insecticidal properties. These toxins are widely sought after for controlling...Full Text Available

Studies on the mechanism of action of enterotoxin-induced fluid secretion in the gut

A short-chain neurotoxin Pseudechis australis a (toxin Pa a) was isolated from the venom of an Australian elapid snake Pseudechis australis (king brown snake) by sequential chromatography on CM-cellulose, Sephadex G-50 and CM-cellulose columns. Toxin Pa a has an LD50 (intravenous) value of 76 micrograms/kg body wt. in mice and consists of 62 amino acid residues. The amino acid sequence of Pa a shows considerable homology with those of short-chain neurotoxins of elapid snakes, especially of true sea snakes. PMID:4091794

1985-12-01

Tests for the diagnosis of Clostridium difficile infection: the next generation.

The mechanism of action of Clostridium difficile enterotoxin A (CA), of Escherichia coli enterotoxin (STa) and of cholera toxin (CT), which are known to cause severe diarrhea, were studied in a preparation of ligated jejunal loops of anesthetized rats in vivo. The toxins were administered intraluminally. Pharmacological agents, which were tested for their potency to influence toxin-related effects, were administered subcutaneously. Net fluid transport was determined gravimetrically, prostaglandin (PG) E_2-output into the lumen, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) contents in the mucosa were measured by radioimmunoassay, serotonin-(5-HT)-output into the lumen was determined by high performance liquid chromatography. The histopathological effects of CA and CT were examined by light- and scanning electron microscopy. All three toxins caused net fluid secretion ...

1992-01-01

A CD33-specific single-chain immunotoxin mediates potent apoptosis of cultured human myeloid leukaemia cells.

Clostridium difficile (C. difficile) causes 25-30% of cases of antibiotic associated diarrhea and most cases of pseudomembranous colitis. Patients presenting with diarrhea after hospitalization for 3 or more days should be tested for C. difficile. There are many options available for testing, each of which has inherent advantages and disadvantages. Most laboratories perform toxin testing using an enzyme immunoassay method. In general these tests have sensitivities ranging from 60 to 70% and specificities of 98%. When using these methods, symptomatic patients with negative tests should be tested by another more sensitive method. Until recently, cell culture cytotoxicity neutralization assays (CCNAs) were considered the gold standard in the U.S. A two-step algorithm using an EIA for glutamate dehydrogenase detection followed by testing positives using CCNA, offered an improved alternative until the availability of molecular assays. Although early studies that ...

2011-03-03

Ophidian envenomation strategies and the role of purines.

A novel single-chain immunotoxin was constructed by combining a CD33-specific single chain Fv (scFv) antibody fragment with an engineered variant of Pseudomonas exotoxin A (ETA). The variant toxin carries the KDEL peptide at its C-terminus, a cellular peptide mediating improved retrograde transport to the endoplasmic reticulum. The purified recombinant fusion protein induced potent apoptosis of the human myeloid cell lines U937, HL-60 and THP-1. Up to 98% of U937 cells were eliminated after treatment for 72 h with a single dose of 500 ng/ml (c. 7 nmol/l). Killing was antigen-specific and occurred by apoptosis. A control protein, consisting of a CD19-specific scFv antibody fragment fused to the ETA-KDEL toxin, failed to induce death of the CD19-negative cell lines U937, HL-60 and THP-1. The CD33-ETA toxin also mediated apoptosis of fresh patient-derived acute myeloid leukaemia cells from bone marrow and peripheral blood. The ...

2006-04-01

Intraprostatic botulinum toxin type A administration: evaluation of the effects on sexual function

Snake envenomation employs three well integrated strategies: prey immobilization via hypotension, prey immobilization via paralysis, and prey digestion. Purines (adenosine, guanosine and inosine) evidently play a central role in the envenomation strategies of most advanced snakes. Purines constitute the perfect multifunctional toxins, participating simultaneously in all three envenomation strategies. Because they are endogenous regulatory compounds in all vertebrates, it is impossible for any prey organism to develop resistance to them. Purine generation from endogenous precursors in the prey explains the presence of many hitherto unexplained enzyme activities in snake venoms: 5'-nucleotidase, endonucleases (including ribonuclease), phosphodiesterase, ATPase, ADPase, phosphomonoesterase, and NADase. Phospholipases A(2), cytotoxins, myotoxins, and heparinase also participate in purine liberation, in addition to their better known functions. Adenosine contributes to ...

2002-04-01

British Library Electronic Table of Contents (United Kingdom)

OBJECTIVE --To evaluate the consequences on male sexual function of intraprostatic injection of botulinum toxin type A (BoNT/A) as a treatment for benign prostatic hyperplasia (BPH). Although BoNT/A is effective in decreasing symptoms of BPH, neuronal impairment caused by the neurotoxin might affect emission/ejaculation. These aspects have not been evaluated before. PATIENTS AND METHODS --In all, 16 sexually active men aged >60 years with BPH/benign prostatic enlargement (BPE), International Prostate Symptom Score (IPSS) -8 and a maximum urinary flow rate (Qmax) <15mL/s refractory to standard medical therapy volunteered for the study. --Patients were injected transrectally, under ultrasonographic control, with 200U of BoNT/A in the prostate. Evaluation was carried out at baseline and 1, 3 ...

2011-01-01

Cloning and characteristics of Brn1 gene in Curvularia lunata causing leaf spot in maize

British Library Electronic Table of Contents (United Kingdom)

The full length cDNA of the Brn1 was first cloned, and then expression of the Brn1 was analyzed and the function was identified by silencing technology. Results show that the full length cDNA of the C. lunata Brn1 gene contains 1001 base pairs and an 801?bp open reading frame encoding 267 amino acids. Semi-quantitative PCR analysis shows that the expression of Brn1 at 96?h is significantly higher than at 24 and 72?h (p?Brn1-silenced transformants were light brown in culture filtrate, and have significantly reduced toxin production relative to the wild-type. These results imply that Brn1 gene in C. lunata is not only involved in 1,8-dihydroxynaphthalene melanin synthesis, but is also relatively associated with toxin biosynthesis of the pathogen.

2011-01-01

The ecological role of bacteriocins in bacterial competition.

Sequence and Organization of pXO1, the Large Bacillus anthracis Plasmid Harboring the Anthrax Toxin Genes

Bacteriocins are an abundant class of antimicrobial molecules that appear to mediate population dynamics within species. The bacteriocins of Escherichia coli have served as a model for exploring the ecological role of these potent toxins. Studies suggest that colicins provide a competitive edge in nutrient-poor environments and that there might be a trade-off between the costs and benefits of colicin production. PMID:10203843

1999-03-01

Salmonella enterica Serovar Typhimurium Expressing a Chromosomally Integrated Copy of the Bacillus anthracis Protective Antigen Gene Protects Mice against an Anthrax Spore Challenge

The Bacillus anthracis Sterne plasmid pXO1 was sequenced by random, “shotgun” cloning. A circular sequence of 181,654 bp was generated. One hundred forty-three open...Full Text Available

1999-10-01

Primary structures of four trypsin inhibitor E homologs from venom of Dendroaspis angusticeps: structure-function comparisons with other dendrotoxin homologs.

Protective immunity against infection with Bacillus anthracis is almost entirely based on a response to the protective antigen (PA), the binding moiety for the two other toxin components....Full Text Available

2003-07-01

Phthalate esters used as plasticizers in packed red blood cell storage bags may lead to progressive toxin exposure and the release of pro-inflammatory cytokines

Four trypsin inhibitor homologs, the first known from Dendroaspis angusticeps venom, were characterized using a combination of gel filtration, cation exchange, reverse-phase liquid chromatography, Edman degradation and mass spectrometry. The four toxins comprise two 57 residue and two 59 residue isoforms. The long toxins possess a Lys-Gln N-terminal extension lacked by the short toxins. The only other structural difference is an Arg/His replacement at position 55. The long Arg55 variant is identical to trypsin inhibitor E from the venom of Dendroaspis polylepis. The name epsilon-dendrotoxin is suggested so as to follow the nomenclature of Benishin, C.G., Sorensen, R.G., Brown, W.E., Krueger, B.K., Blaustein, M.P., 1988. Four polypeptide components of green mamba venom selectively block certain potassium channels in rat brain synaptosomes. Mol. Pharmacol. 34, 152-159. Among snake venom protease inhibitors, the ...

2002-03-01

A new type of scorpion Na⁺-channel-toxin-like polypeptide active on K⁺ channels

Phthalate esters (PE's) are plasticizers used to soften PVC-based medical devices. PE's are the most abundant man-made pollutants and increase the risk of developing an allergic respiratory disease...Full Text Available

2009-07-01

Peru-15, an improved live attenuated oral vaccine candidate for Vibrio cholerae O1.

We have purified and characterized two peptides, named KAaH1 and KAaH2 (AaH polypeptides 1 and 2 active on K⁺ channels, where AaH stands for Androctonus australis Hector),...Full Text Available

2005-06-01

Further evidence supporting the concurrent influence of aflatoxin and manganese

Cholera vaccine candidate Peru-15 was derived from a Vibrio cholerae O1 El Tor Inaba strain by deleting the cholera toxin genetic element, introducing the gene encoding cholera toxin B subunit into recA, and screening for nonmotility. In a controlled study, Peru-15 (2 x 10(8) cfu) was administered to 11 volunteers. No vaccinee developed diarrhea, and 10 of 11 had > 4-fold rises in vibriocidal antibody titers. One month later, 5 vaccinees and 5 control volunteers were challenged with wild type V. cholerae O1. Four of 5 controls developed diarrhea (mean, 1.9 L). Two Peru-15 vaccinees developed diarrhea, 1 with < 0.3 L and 1 with approximately 1.0 L; this latter volunteer had not developed a significant vibriocidal immune response to vaccination. Peru-15 shows promise as a single-dose, oral cholera vaccine that is safe, immunogenic, and protective. PMID:7561195

1995-10-01

Effect of a maltodextrin-electrolyte, a maltodextrin-nutrient-electrolyte and a standard electrolyte solution on water and electrolyte fluxes in the secreting rat intestine.

Trace elements, including manganese may afford protection from deleterious effects of aflatoxin. Young male Fischer rats received ip injections of aflatoxin B1 (AFB1) in dimethyl sulfoxide (DMSO), 1 mg/kg, 2 mg/kg or 4 mg/kg. Control groups received DMSO ip or no injection. All animals were intubated with 3 microCi of (/sup 54/Mn)-MnCl/sub 2/ 12 hr post-injection. Sacrifice occurred 72 hr after gavage of the radiolabel. All tested levels of AFB1 affected the loss of total body radioactivity. This response was observed within 12 hr when toxin-treated groups excreted almost 4 times more counts than controls. From 12-36 hr following radiolabel administration, AFB1 appeared to enhance excretion; by 72 hr, toxin-treated animals (especially those receiving higher doses) appeared to conserve the metal. Aflatoxicosis manifested itself through reduced body weight gain. The data provide support evidence that Mn and AFB1 biointeract.

1987-04-01

Differentiation to adipocytes in accompanied by an increase in the amounts of Gi- and Go-proteins in 3T3-L1 cells

The effects of a maltodextrin (dextrose equivalent 12)-electrolyte solution and a maltodextrin-electrolyte solution with added nutrients on net water and electrolyte transport in the secreting rat intestine was compared with the citrate-World Health Organization oral rehydration solution to determine the need for a clinical trial to evaluate the efficacy of these maltodextrin solutions in acute diarrhoea treatment. Cholera toxin consistently produced net water secretion (-36.5 +/- 9.9 mean +/- SEM microliter/min/g dry weight of intestine). All three solutions reversed the cholera toxin-induced net intestinal water secretion to net absorption. Significantly greater net water absorption occurred from the maltodextrin-electrolyte solution compared to the World Health Organization solution (P < 0.05) but not when compared to the maltodextrin-electrolyte-nutrient solution. Net sodium, potassium and chloride fluxes due to the World Health ...

1993-12-01

1 2 3 4 5

Inactivation of aflatoxin B1 by using the synergistic effect of hydrogen peroxide and gamma radiation

Treatment of cultures of 3T3-L1 cells with methylisobutyl-xanthine and dexamethasone has been shown to result in accumulation of lipid and conversion to the morphology of adipocytes in more than 90% of the cells. The status of the stimulatory (Gs), inhibitory (Gi) and Go-proteins during the course of 3T3-L1 differentiation was examined. The amount of alpha subunit of Gs (#alpha#Gs), assayed by radiolabeling in the presence of cholera toxin and ["3"2P]NAD"+, increased upon differentiation as previously described by others. The amounts of #alpha#Gi and #alpha#Go assayed by radiolabeling in the presence of pertussis toxin and ["3"2P]NAD"+ increased 3-fold upon differentiation. Immunoblots of cell membranes subjected to gel electrophoresis in sodium dodecyl sulfate were probed with two rabbit antisera raised against bovine brain #alpha#Go and with one raised against the#beta#-subunit of the bovine rod-outer-segment G-protein, referred to as ...

1986-06-08

Functionalized luminescent oxide nanoparticles for sodium channel imaging at the single molecule level

Inactivation of aflatoxin B1 was studied by using gamma radiation and hydrogen peroxide. A 100-krad dose of gamma radiation was sufficient to inactivate 50 micrograms of aflatoxin B1 in the presence of 5% hydrogen peroxide, and 400 krad was required for total degradation of 100 micrograms of aflatoxin in the same system. Degradation of aflatoxin B1 was confirmed by high-pressure liquid chromatographic and thin-layer chromatographic analysis. Ames microsomal mutagenicity test showed loss of aflatoxin activity. This method of detoxification also reduces the toxin levels effectively in artificially contaminated groundnuts.

1989-02-01

Follicle-stimulating hormone receptor-mediated uptake of "4"5Ca"2"+ by cultured rat Sertoli cells does not require activation of cholera toxin- or pertussis toxin-sensitive guanine nucleotide binding proteins or adenylate cyclase

Lanthanide-ion doped oxide nanoparticles were functionalized for use as fluorescent biological labels. These nanoparticles are synthesized directly in water which facilitates their functionalization, and are very photostable without emission intermittency. Nanoparticles functionalized with guanidinium groups act as artificial toxins and specifically target sodium channels. They are individually detectable in cardiac myocytes, revealing a heterogeneous distribution of sodium channels. Functionalized oxide nanoparticles appear as a novel tool particularly well adapted to long-term single-molecule tracking.

2005-04-01

Botulinum toxin—Beyond wrinkles

We have previously reported that FSH stimulates flux of 45Ca2+ into cultured Sertoli cells from immature rats via voltage-sensitive and voltage-independent calcium channels. In the present study, we show that this effect of FSH does not require cholera toxin (CT)- or pertussis toxin (PT)-sensitive guanine nucleotide binding (G) protein or activation of adenylate cyclase (AC). Significant stimulation of 45Ca2+ influx was observed within 1 min, and maximal response (3.2-fold over basal levels) was achieved within 2 min after exposure to FSH. FSH-stimulated elevations in cellular cAMP paralleled increases in 45Ca2+ uptake, suggesting a possible coupling of AC activation to 45Ca2+ influx. (Bu)2cAMP, however, was not able to enhance 45Ca2+ uptake over basal levels at a final concentration of 1000 microM, although a concentration-related increase in androstenedione conversion to estradiol was evident. Exposure of Sertoli cells to CT (10 ng/ml) ...

1990-01-01

British Library Electronic Table of Contents (United Kingdom)

Botulinum neurotoxin is produced by the bacterium, Clostridium botulinum. The neurotoxin inhibits acetylcholine at the neuromuscular junction, thus interfering with overall muscular contraction. Botulinum neurotoxin is commonly used for the following medical conditions: cervical dystonia, upper limb spasticity, blepharospasm, strabismus, and hyperhydrosis. However, the use of botulinum neurotoxin was recently approved for the prophylaxis of headaches in adults with chronic migraines. The proposed mechanism of botulinum neurotoxin is no longer solely limited to the inhibition of acetylcholine. There are new mechanisms emerging that involve inhibition of proinflammatory agents and neuropeptides involved in chronic pain. Consequently, there is a disruption of the overall sensory feedback loop...

2011-01-01

Neuromuscular effects of candoxin, a novel toxin from the venom of the Malayan krait (Bungarus candidus).

The central analgesia induced by antimigraine drugs is independent from Gi proteins: superiority of a fixed combination of indomethacin, prochlorperazine and caffeine, compared to sumatriptan, in an in vivo model

1 Candoxin (MW 7334.6), a novel toxin isolated from the venom of the Malayan krait Bungarus candidus, belongs to the poorly characterized subfamily of nonconventional three-finger toxins present in Elapid venoms. The current study details the pharmacological effects of candoxin at the neuromuscular junction. 2 Candoxin produces a novel pattern of neuromuscular blockade in isolated nerve-muscle preparations and the tibialis anterior muscle of anaesthetized rats. In contrast to the virtually irreversible postsynaptic neuromuscular blockade produced by curaremimetic alpha-neurotoxins, the neuromuscular blockade produced by candoxin was rapidly and completely reversed by washing or by the addition of the anticholinesterase neostigmine. 3 Candoxin also produced significant train-of-four fade during the onset of and recovery from neuromuscular blockade, both, in vitro and in vivo. The fade phenomenon has been attributed to a blockade of putative ...

2003-06-01

British Library Electronic Table of Contents (United Kingdom)

A hypofunctionality of Gi proteins has been found in migraine patients. The fixed combination of indomethacin, prochlorperazine and caffeine (Indoprocaf) is a drug of well-established use in the acute treatment of migraine and tension-type headache. The aim of this study was to investigate if Indoprocaf was able to exert its central antinociceptive action when Gi proteins activity is abolished by pertussis toxin (PTX), compared to its single active ingredients and to sumatriptan. The mice model of abdominal constriction test induced by an i.p. injection of a 0.6% solution of acetic acid was used. The study showed that Indoprocaf (a fixed combination of indomethacin 1?mg/kg, prochlorperazine 1?mg/kg and caffeine 3?mg/kg, s.c.) and sumatriptan (20?mg/kg, s.c.) exert their central antinocicep...

2009-01-01

Nutrition and Physical Activity in Aging, Obesity, and Cancer

British Library Electronic Table of Contents (United Kingdom)

A wide variety of phytochemicals present in our diet, including fruits, vegetables, and spices, have been shown to possess a broad range of health-beneficial properties. The cytoprotective and restorative effects of dietary phytochemicals are likely to result from the modulation of several distinct cellular signal transduction pathways. Many dietary phytochemicals that are synthesized as secondary metabolites function as toxins, that is, -phytoalexins,- and hence protect plants against insects and other damaging organisms and stresses. However, at the relatively low doses consumed by humans and other mammals, these same toxic plant-derived chemicals, as mild stressors, activate adaptive cellular response signaling, conferring stress resistance and other health benefits. This phenomenon has...

2011-01-01

Impact of Invasive Cane Toads on Australian Birds

British Library Electronic Table of Contents (United Kingdom)

Abstract: The cane toad (Bufo marinus), a large, toxic, American anuran, was introduced to Australia in 1935. Populations of many of Australia's reptiles (snakes, varanid lizards, crocodiles) and carnivorous mammals (dasyurid marsupials) have declined because these predators are killed by the toad's powerful toxins. In contrast to these well-studied species, little is known about the cane toads impacts on Australian birds. We reviewed published and unpublished data on behavioral interactions between Australian avian predators and cane toads and collated distributional and dietary information to identify avian taxa potentially at risk from cane toad invasion. Cane toads are sympatric with 172 frog-eating bird species in Australia, and an additional 8 bird species overlap with the predicted ...

2009-01-01

High-dose insulin: A consecutive case series in toxin-induced cardiogenic shock

British Library Electronic Table of Contents (United Kingdom)

Context. Cardiovascular medication overdoses can be difficult to treat. Various treatment modalities are currently recommended. Objective. To describe patient outcomes and adverse events of high-dose insulin therapy in consecutive overdose patients in cardiogenic shock after implementation of a high-dose insulin protocol (1-10 U/kg/h, while avoiding or tapering off vasopressors). Methods. This is an observational consecutive case series of patients identified from a registry. Data were collected by retrospective chart review of patients treated by our toxicology service with this protocol from February 2007 until March 2010. Results. Twelve patients were treated with high-dose insulin. The mean age was 36.5 years (SD 11.7). Seven patients had pre-existing vasopressor therapy, and all were ...

2011-01-01

Differential responses of populations of the copepod Acartia hudsonica to toxic and nutritionally insufficient food algae

British Library Electronic Table of Contents (United Kingdom)

Nutritional insufficiency and toxicity are deleterious effects of phytoplankton on grazers. We hypothesize that toxic food is likely to have stronger evolutionary selective effects on grazers than nutritionally insufficient food. We explore this hypothesis in comparative studies of egg production and egg hatching of the copepod Acartia hudsonica challenged with both a toxic and a nutritionally insufficient alga. Experiments lasting 6 days, in which mixtures of different proportions of the suspect and a control alga were offered as food to female copepods, showed that the dinoflagellate Alexandrium fundyense, which bears paralytic shellfish toxins, was toxic to A. hudsonica. In contrast, the diatom Phaeodactylum tricornutum was nutritionally insufficient to A. hudsonica. In another set of e...

2011-01-01

Continuous human cell lines and method of making same

Artificial kidney engineering-Dialysis membrane and dialyzer for blood purification-

Substantially genetically stable continuous human cell lines derived from normal human mammary epithelial cells (HMEC) and processes for making and using the same. In a preferred embodiment, the cell lines are derived by treating normal human mammary epithelial tissue with a chemical carcinogen such as benzo(a)pyrene. The novel cell lines serve as useful substrates for elucidating the potential effects of a number of toxins, carcinogens and mutagens as well as of the addition of exogenous genetic material. The autogenic parent cells from which the cell lines are derived serve as convenient control samples for testing. The cell lines are not neoplastically transformed, although they have acquired several properties which distinguish them from their normal progenitors. 2 tabs.

1985-07-01

Aluminium Phosphide-Induced Esophageal Stricture Palliation with Polyflex Stent

Since artificial organs are intended to replicate chemical processes, knowledge of chemical engineering is essential in their design so that they will function with the maximum efficiency. The most commonly used artificial organ is the artificial kidney, a machine that performs a treatment known as hemodialysis. This process cleanses the bodies of renal failure patients by dialysis and filtration which are simple physiochemical processes. Hemodialysis membranes act to remove accumulated uremia toxins, excess ions and water from the patient via the dialysate, and to supply from the dialysate those ions that are insufficient. This paper describes dialysis membranes and dialyzers for blood purification, the solute transport mechanism of the membrane, and a technical evaluation of the dialysis membrane. Lastly, the next generation of artificial kidney is reviewed. 71 refs., 12 figs., 7 tabs.

1997-08-01

British Library Electronic Table of Contents (United Kingdom)

A 21-year-old woman developed midesophageal stricture two weeks after ingestion of aluminium phosphide (AlP) tablets. Aluminium phosphide is a lethal protoplasmic toxin and is also the most common cause of suicidal poisoning in northern India. Upper gastrointestinal endoscopy (UGIE) showed a tight esophageal stricture 29?cm from the incisors with a circumferential ulcer. Dilatation up to 17?mm was done using Savary-Gilliard dilators. She had repeated dilatations three times at nearly two-week intervals. In view of the resistant stricture, a silicone Polyflex stent was placed across the stricture and removed after 3?months; there was no recurrence of stricture even after three months of follow-up. Patients with recurrent esophageal stricture and those with fistula may benefit from silicone ...

2008-01-01

Allelopathic interactions between Prorocentrum micans and Skeletonema costatum or Karenia mikimotoi in laboratory cultures

British Library Electronic Table of Contents (United Kingdom)

Algal allelopathy is an ecological/physiological phenomenon that has focused attention on the interactions among algae and the production of algal toxins. We investigated the allelopathic interactions between the dinoflagellate genus Prorocentrum micans and diatom genus Skeletonema costatum and between P. micans and dinoflagellate genus Karenia mikimotoi using bi-algal cultures. Because the effects were species-specific and size-dependent, we evaluated the effect of different initial densities. At low densities of P. micans and high densities of S. costatum inoculated into the same medium, the growth of P. micans was weakly restrained, whereas the growth of S. costatum was significantly suppressed. S. costatum and K. mikimotoi were strongly inhibited by P. micans, in both the bi-algal cult...

2011-01-01

Viral RNA testing and automation on the bead-based CBNE detection microsystem.

Sequences, geographic variations and molecular phylogeny of venom phospholipases and threefinger toxins of eastern India Bungarus fasciatus and kinetic analyses of its Pro31 phospholipases A2.

We developed prototype chemistry for nucleic acid hybridization on our bead-based diagnostics platform and we established an automatable bead handling protocol capable of 50 part-per-billion (ppb) sensitivity. We are working towards a platform capable of parallel, rapid (10 minute), raw sample testing for orthogonal (in this case nucleic acid and immunoassays) identification of biological (and other) threats in a single sensor microsystem. In this LDRD we developed the nucleic acid chemistry required for nucleic acid hybridization. Our goal is to place a non-cell associated RNA virus (Bovine Viral Diarrhea, BVD) on the beads for raw sample testing. This key pre-requisite to showing orthogonality (nucleic acid measurements can be performed in parallel with immunoassay measurements). Orthogonal detection dramatically reduces false positives. We chose BVD because our collaborators (UC-Davis) can supply samples from persistently infected animals; and because proof-of-concept field testing ...

2008-09-01

Regulation of the phosphoinositide pathway in cultured Sertoli cells from immature rats: effects of follicle-stimulating hormone and fluoride

Eight phospholipases A2 (PLAs) and four three-finger-toxins (3FTx) from the pooled venom of Bungarus fasciatus (Bf) were previously studied and sequenced, but their expression pattern in individual Bf venom and possible geographic variations remained to be investigated. We herein analyze the individual venom of two Bf specimens from Kolkata (designated as KBf) to address this question. Seven PLAs and five 3FTx were purified from the KBf venoms, and respective cDNAs were cloned from venom glands of one of the snakes. Comparison of their mass and N-terminal sequence revealed that all the PLAs were conserved in both KBf venoms, but that two of their 3FTx isoforms were variable. When comparing the sequences of these KBf-PLAs with those published, only one was found to be identical to that of Bf Vb-2, and the other five were 94-98% identical to those of Bf II, III, Va, VI and XI-2, respectively. Notably, the most abundant PLA isoforms of Bf and KBf venoms contain Pro31 ...

2006-12-08

Production of Shiga-like toxins by Escherichia coli O157:H7 can be influenced by the neuroendocrine hormone norepinephrine.

Many hormones elicit effects on target cells by stimulating the enzyme phospholipase-C, which catalyzes the hydrolysis of phosphoinositides to the intracellular second messengers diacylglycerol and inositol phosphates. The present study examined the roles of FSH and guanine nucleotide-binding proteins (G-proteins) in regulating the hydrolysis of phosphoinositides in Sertoli cells. Sertoli cell cultures prepared from 16- to 18-day-old rats were incubated for 24 h with myo-[2-3H] inositol to label endogenous phospholipids. Treatment of cells from 0.5-20 min with preparations of ovine FSH ranging in potency from 1-60 times that of NIH FSH S1 did not affect accumulation of inositol phosphates. Levels of total [3H]inositol phosphates [[3H]inositol mono-, di-, and triphosphates (IP, IP2, and IP3)] in FSH-treated cultures was 75-120% the levels in control cultures over the various time intervals studied. Addition of testosterone and the combination of testosterone plus retinoic acid, agents ...

Molecular cloning, characterization, and expression of human ADP-ribosylation factors: Two guanine nucleotide-dependent activators of cholera toxin

To examine whether the neuroendocrine hormone norepinephrine may influence the production of the Shiga-like toxins (SLTs), several Escherichia coli O157:H7 clinical isolates were grown in the presence or absence of norepinephrine. An in vitro culture system consisting of low (<1500 colony-forming units/ml) initial concentrations of inocula into a serum-based medium was used to more closely approximate in vivo conditions. The growth of all isolates was increased several logs in the presence of norepinephrine, as compared with the growth in controls, during a 24-hour growth period. Controls included additional dextrose as well as the use of the norepinephrine metabolite normetanephrine, which contains one more methyl group than norepinephrine and hence would serve as a better energy source for growth if the effect were solely nutritionally mediated. During the 24 hours of growth, the production of cell-associated SLT-I on a protein-equivalent basis was shown to be ...

1996-10-01

Involvement of a glutamergic mechanism in gamma-dendrotoxin-induced hippocampal neuronal cell loss in the rat.

ADP-ribosylation factors (ARFs) are small guanine nucleotide-binding proteins that enhance the enzymatic activities of cholera toxin. Two ARF cDNAs, ARF1 and ARF3, were cloned from a human cerebellum library. Based on deduced amino acid sequences and patterns of hybridization of cDNA and oligonucleotide probes with mammalian brain poly(A)"+ RNA, human ARF1 is the homologue of bovine ARF1. Human ARF3, which differs from bovine ARF1 and bovine ARF2, appears to represent a newly identified third type of ARF. Hybridization patterns of human ARF cDNA and clone-specific oligonucleotides with poly(A)"+ RNA are consistent with the presence of at least two, and perhaps four, separate ARF messages in human brain. In vitro translation of ARF1, ARF2, and ARF3 produced proteins that behaved, by SDS/PAGE, similar to a purified soluble brain ARF. Deduced amino acid sequences of human ARF1 and ARF3 contain regions, similar to those in other G proteins, that are believed to be ...

1989-01-01

1 2 3 4 5

Experimental parameters differentially affect the humoral response of the cholera-toxin-based murine model of food allergy

The epileptogenic and neurodegenerative effects of gamma-dendrotoxin, from Dendroaspis angusticeps, a specific blocker of a non-inactivating, voltage-sensitive K+ channel, were studied after focal injection into one dorsal hippocampus in rats pretreated with CGP040116, a N-methyl-D-aspartate (NMDA) receptor antagonist, and in rats bearing a monolateral surgical lesion of the Schaffer collaterals whose terminals originate from CA3 pyramids and release glutamate in the CA1 hippocampal area. Administration of 35 pmol gamma-dendrotoxin elicited in all of the treated animals (n=8) bilateral EEG discharges and damage to the hippocampal formation. Quantitation of the damage revealed significant bilateral neuronal cell loss in the CA1, CA3 and CA4 pyramidal cell layers. The lowest dose (0.35 pmol; n=4) of the toxin used did not affect EEG activity and failed to cause significant hippocampal cell loss whereas the 3.5 pmol (n=6) dose caused EEG seizures and hippocampal cell ...

2004-03-01

DEFF Research Database (Denmark)

Background: Recent studies have developed a murine model of IgE-mediated food allergy based on oral coadministration of antigen and cholera toxin (CT) to establish a maximal response for studying immunopathogenic mechanisms and immunotherapeutic strategies. However, for studying subtle immunomodulating factors or factors effective during response initiation, this maximal response-based model is less suitable due to a lack of sensitivity. Therefore, in attempts to identify essential parameters to fine-tune the immune response towards a submaximal level, potentially more sensitive, we were interested in characterizing the individual effects of the parameters in the CT-based model: CT dose, antigen type and dose, and number of immunizations. Methods: BALB/c mice were orally sensitized weekly for 3 or 7 weeks with graded doses of CT and various food antigens (soy-trypsin inhibitor, ovalbumin or ovomucoid). Antigen-specific lgG1, IgG2a, IgA and IgE were monitored by ...

2003-01-01

The multidrug resistance efflux complex, EmrAB from Escherichia coli forms a dimer in vitro

Rhipicephalus sanguineus: vector of a new spotted fever group rickettsia in the United States.

Tripartite efflux systems are responsible for the export of toxins across both the inner and outer membranes of Gram negative bacteria. Previous work has indicated that EmrAB-TolC from Escherichia coli is such a tripartite system, comprised of EmrB an MFS transporter, EmrA, a membrane fusion protein and TolC, an outer membrane channel. The whole complex is predicted to form a continuous channel allowing direct export from the cytoplasm to the exterior of the cell. Little is known, however, about the interactions between the individual components of this system. Reconstitution of EmrA + EmrB resulted in co-elution of the two proteins from a gel filtration column indicating formation of the EmrAB complex. Electron microscopic single particle analysis of the reconstituted EmrAB complex revealed the presence of particles approximately 240 x 140 A, likely to correspond to two EmrAB dimers in a back-to-back arrangement, suggesting the dimeric EmrAB form is the ...

2009-03-06

Detecting exposure to environmental organic toxins in individual cells: towards development of a micro-fabricated device

A rickettsia related to but distinct from the spotted fever agent, Rickettsia rickettsii, has been detected in 167 (18.9%) of 884 Rhipicephalus sanguineus taken off dogs in central and northern Mississippi. The organisms could readily be isolated in male meadow voles (Microtus pennsylvanicus), where it produced massive infections in the tissues of tunica vaginalis. It was practically nonpathogenic for male guinea pigs, although inoculation of these animals with infected tunica vaginalis of voles afforded in 30 of 38 instances solid immunity to challenge with virulent R. rickettsii. The Rhipicephalus rickettsia grew well in monolayers of chicken embryo fibroblast, Vero, mouse L, and HeLa cells. Cytopathogenic effects were minimal unless large concentrations of rickettsiae were used as inocula. It also could be established in embryonated hen eggs but only after injection of massive doses of L cell-propagated organisms. Serological tests (complement fixation, microagglutination and/or ...

1975-07-01

Triphenylmethylphosphonium cation distribution as a measure of hormone-induced alterations in white adipocyte membrane potential

A new method is being developed to quickly screen for the human exposure potential to polycyclic aromatic hydrocarbons (PAHs) and organochlorines (OCs). The development involves two key elements: identifying suitable signals that represent intracellular changes that are specific to PAH and OC exposure, and constructing a device to guide the biological cell growth so that signals from individual cells are consistent and reproducible. We are completing the identification of suitable signals by using synchrotron radiation-based (SR) Fourier-transform infrared (FTIR) spectromicroscopy in the mid-infrared region (4000-400 cm-1). Distinct changes have been observed in the IR spectra after treatment of human cells in culture medium with PAHs and OCs. The potential use of this method for detecting exposure to PAHs and OCs has been tested and compared to a reverse transcription polymerase chain reaction (RT-PCR) assay that quantifies increased expression of the CYP1A1 gene in response to exposu ...

1999-01-10

Structural determinants of alpha-bungarotoxin binding to the sequence segment 181-200 of the muscle nicotinic acetylcholine receptor #alpha# subunit: Effects of cysteine/cystine modification and species-specific amino acid substitution

Triphenylmethylphosphonium (TPMP+) partitions into the mitochondrial and cytosolic compartments in the rat white adipocyte in a potential-dependent fashion. The relationship between (/sup 3/H)TPMP+ distribution, intracellular cAMP generation and lipolysis in response to hormones and cAMP-mimetic compounds was examined. Half-maximal (/sup 3/H)TPMP+ efflux and glycerol release were produced by 15 and 9 nM adrenocorticotropin, 170 and 110 nM 1-epinephrine, 70 and 27 microM isobutylmethylxanthine and 800 and 750 microM dibutyryl cAMP, respectively. Hormone-stimulated cAMP generation was also correlated with (/sup 3/H)TPMP+ efflux and lipolysis in terms of concentration dependency. In kinetic experiments, glycerol release and (/sup 3/H)TPMP+ efflux in response to adrenocorticotropin or cholera toxin proceeded over a similar time course, whereas an earlier rise in cAMP generation was detected. The depolarizing effect of lipolytic compounds was localized to the ...

1982-01-01

Risk Assessment and Ecological Effects of Transgenic Bacillus thuringiensis Crops on Non-Target Organisms(F).

The sequence segment 181-200 of the Torpedo nicotinic acetylcholine receptor (nAChR) #alpha#subunit forms a binding site for #alpha#-bungarotoxin (#alpha#-BTX). Synthetic peptides corresponding to the homologous sequences of human, calf, mouse, chicken, frog, and cobra muscle nAChR #alpha#1 subunits were tested for their ability to bind "1"2"5I-#alpha#-BTX, and differences in #alpha#-BTX affinity were determined by using solution (IC_5_0s) and solid-phase (K_ds) assays. Panels of overlapping peptides corresponding to the complete #alpha#1 subunit of mouse and human were also tested for #alpha#-BTX binding, but other sequence segments forming the #alpha#-BTX site were not consistently detectable. The role of a putative vicinal disulfide bound between Cys-192 and -193, relative to the Torpedo sequence, was determined by modifying the peptides with sulfhydryl reagents. Reduction and alkylation of the peptides decreased #alpha#-BTX binding, whereas oxidation of the peptides had little ...

Present status of biological effects of toxic metals in the environment: lead, cadmium, and manganese

Kong-Ming Wu (Corresponding author) The application of recombinant DNA technology has resulted in many insect-resistant varieties by genetic engineering (GE). Crops expressing Cry toxins derived from Bacillus thuringiensis (Bt) have been planted worldwide, and are an effective tool for pest control. However, one ecological concern regarding the potential effects of insect-resistant GE plants on non-target organisms (NTOs) has been continually debated. In the present study, we briefly summarize the data regarding the development and commercial use of transgenic Bt varieties, elaborate on the procedure and methods for assessing the non-target effects of insect-resistant GE plants, and synthetically analyze the related research results, mostly those published between 2005 and 2010. A mass of laboratory and field studies have shown that the currently available Bt crops have no direct detrimental effects on NTOs due to their narrow spectrum of activity, and Bt crops are ...

2011-07-01

Paraquat induces oxidative stress and neuronal cell death; neuroprotection by water-soluble Coenzyme Q_1_0

The number of reports concerning the chemical toxicology of metals which are released in the environment by natural as well as anthropogenic sources, have been increasing constantly. Lead, cadmium, and manganese have found a variety of uses in industry, craft, and agriculture owing to their physical and chemical properties. The environmental burden of heavy metals has been rising substantially by smelter emission in air and waste sewage in water. Further, organic compounds of lead and manganese used as antiknock substances in gasoline are emitted into the atmosphere by automobile exhaustion. Such environmental contamination of air, water, soil, and food is a serious threat to all living kinds. Although these metals are known to produce their toxic effects on a variety of body systems, much emphasis has been placed on their effects on the nervous system owing to apparent association of relatively low or ''subclinical'' levels of metallic exposure with ...

1984-08-01

Nod2 sensing of lysozyme-digested peptidoglycan promotes macrophage recruitment and clearance of S. pneumoniae colonization in mice.

Neuronal cell death induced by oxidative stress is correlated with numerous neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and stroke. The causes of sporadic forms of age-related neurodegenerative diseases are still unknown. Recently, a correlation between paraquat exposure and neurodegenerative diseases has been observed. Paraquat, a nonselective herbicide, was once widely used in North America and is still routinely used in Taiwan. We have used differentiated Human Neuroblastoma (SHSY-5Y) cells as an in vitro model to study the mechanism of cell death induced by paraquat. We observed that paraquat-induced oxidative stress in differentiated SHSY-5Y cells as indicated by an increase in the production of cellular reactive oxygen species (ROS). Furthermore, apoptosis was evident as indicated by cellular and nuclear morphology and DNA fragmentation. Interestingly, pretreatment of SHSY-5Y cells with water-soluble Coenzyme Q_1_0 (CoQ_1_0) before ...

2004-11-15

High extracellular calcium attenuates adipogenesis in 3T3-L1 preadipocytes

Streptococcus pneumoniae colonizes the mucosal surface of the human upper respiratory tract. A colonization event is gradually cleared through phagocytosis by monocytes/macrophages that are recruited to the airway lumen. Here, we sought to define the bacterial and host factors that promote monocyte/macrophage influx and S. pneumoniae clearance using intranasal bacterial challenge in mice. We found that the recruitment of monocytes/macrophages required their expression of the chemokine receptor CCR2 and correlated with expression of the CCR2 ligand CCL2. Production of CCL2 and monocyte/macrophage recruitment were deficient in mice lacking digestion of peptidoglycan by lysozyme (LysM) and cytosolic sensing of the products of digestion by Nod2. Ex vivo macrophages produced CCL2 following bacterial uptake, digestion by LysM, and sensing of peptidoglycan by Nod2. Sensing of digested peptidoglycan by Nod2 also required the pore-forming toxin pneumolysin. The generation ...

2011-08-15

Gene expression profiles deciphering rice phenotypic variation between Nipponbare (Japonica) and 93-11 (Indica) during oxidative stress.

We studied the effect of extracellular Ca"2"+ concentration ([Ca"2"+]_e) on adipocyte differentiation. Preadipocytes exposed to continuous [Ca"2"+]_e higher than 2.5 mmol/l accumulated little or no cytoplasmic lipid compared to controls in 1.8 mmol/l [Ca"2"+]_e. Differentiation was monitored by Oil Red O staining of cytoplasmic lipid and triglyceride assay of accumulated lipid, by RT-PCR analysis of adipogenic markers, and by the activity of glycerol-3-phosphate dehydrogenase (GPDH). Elevated [Ca"2"+]_e inhibited expression of peroxisome proliferator-activated receptor #gamma#, CCAAT/enhancer binding protein #alpha#, and steroid regulatory binding element protein. High [Ca"2"+]_e significantly inhibited differentiation marker expression including adipocyte fatty acid binding protein, and GPDH. The decrease in Pref-1 expression that accompanied differentiation also was prevented by high [Ca"2"+]_e. Treatment of 3T3-L1 cells with high [Ca"2"+]_e did not significantly affect cell number ...

2004-12-10

Detecting and Genotyping Escherichia coli O157:H7 using multiplexed PCR and nucleic acid microarrays

Rice is a very important food staple that feeds more than half the world's population. Two major Asian cultivated rice (Oryza sativa L.) subspecies, japonica and indica, show significant phenotypic variation in their stress responses. However, the molecular mechanisms underlying this phenotypic variation are still largely unknown. A common link among different stresses is that they produce an oxidative burst and result in an increase of reactive oxygen species (ROS). In this study, methyl viologen (MV) as a ROS agent was applied to investigate the rice oxidative stress response. We observed that 93-11 (indica) seedlings exhibited leaf senescence with severe lesions under MV treatment compared to Nipponbare (japonica). Whole-genome microarray experiments were conducted, and 1,062 probe sets were identified with gene expression level polymorphisms between the two rice cultivars in addition to differential expression under MV treatment, which were assigned as Core Intersectional Probesets ...

2010-01-08

Comparative tissue distribution and excretion of orally administered ["3H]diacetoxyscirpenol (anguidine) in rats and mice

Rapid detection and characterization of food borne pathogens such as Escherichia coli O157:H7 is crucial for epidemiological investigations and food safety surveillance. As an alternative to conventional technologies, we examined the sensitivity and specificity of nucleic acid microarrays for detecting and genotyping E. coli O157:H7. The array was composed of oligonucleotide probes (25-30 mer) complementary to four virulence loci (intimin, Shiga-like toxins I and II, and hemolysin A). Target DNA was amplified from whole cells or from purified DNA via single or multiplexed polymerase chain reaction (PCR), and PCR products were hybridized to the array without further modification or purification. The array was 32-fold more sensitive than gel electrophoresis and capable of detecting amplification products from < 1 cell equivalent of genomic DNA (1 fg). Immunomagnetic capture, PCR and a microarray were subsequently used to detect 55 CFU ml-1 (E. coli O157:H7) ...

2000-12-01

Cloning, chromosomal assignment, and regulation of the rat thyrotropin receptor: Expression of the gene is regulated by thyrotropin, agents that increase cAMP levels, and thyroid autoantibodies

A quantitative comparison of tissue distribution and excretion of an orally administered sublethal dose of [3H]diacetoxyscirpenol (anguidine) was made in rats and mice 90 min, 24 hr, and 7 days after treatment. Total recoveries of 95-100% were obtained. Approximately 90% of the dose was excreted in urine and feces during the first 24 hr with a feces:urine ratio of about 1:4.5 in both species. Carcass and tissue radioactivity dropped rapidly during the first 24 hr but remained relatively constant at low, but detectable, levels over the course of the experiment. Few substantive interspecies differences were noted in tissue distribution. At 90 min the highest percentage of dose was in tissues involved in sequestering diacetoxyscirpenol because of high body water/lipid content or the absorption, metabolism, or excretion of the toxin. The rank order of these tissues was generally stable over the course of the experiment. When data were expressed as specific ...

2D modeling and preliminary in vitro investigation of a prototype high gradient magnetic separator for biomedical applications.

A rat thyrotropin (thyroid-stimulating hormone, TSH) receptor cDNA was isolated that encoded a protein of 764 amino acids, M_r 86,528. Transfection of the cDNA caused COS-7 cells to develop a TSH-sensitive adenylate cyclase response and the ability to bind "1"2"5I-labeled TSH; both activities were similar to those of rat FRTL-5 thyroid cells and not duplicated by lutropin. The gene represented by the cDNA was assigned to mouse chromosome 12 and human chromosome 14. Northern analyses identified two species of mRNA, 5.6 and 3.3 kilobases, in FRTL-5 thyroid cells; the transcripts appeared to differ only in the extent of their 3' noncoding sequences. There were minimal amounts of the two mRNAs in rat ovary, and neither was detected in RNA preparations from rat testis, liver, lung, brain, spleen, and FRT thyroid cells, which do not have a functional TSH receptor. TSH decreased both mRNA species 3- to 4-fold within 8 hr in FRTL-5 thyroid cells; down-regulation was dependent on TSH ...

1990-01-01

MANAGEMENT PRE-START REVIEW FINAL REPORT FOR THE BIOSAFETY LEVEL 3 (BSL-3) FACILITY (B368) LAWRENCE LIVERMORE NATIONAL LABORATORY

High gradient magnetic separation (HGMS) of magnetic materials from fluids or waste products has many established industrial applications. However, there is currently no technology employing HGMS for ex-vivo biomedical applications, such as for the removal of magnetic drug- or toxin-loaded spheres from the human blood stream. Importantly, human HGMS applications require special design modifications as, in contrast to conventional use where magnetic elements are permanently imbedded within the separation chambers, medical separators need to avoid direct contact between the magnetic materials and blood to reduce the risk of blood clotting and to facilitate convenient and safe treatment access for many individuals. We describe and investigate the performance of a magnetic separator prototype designed for biomedical applications. First, the capture efficiency of a prototype HGMS separator unit consisting of a short tubing segment and two opposing magnetizable fine ...

2007-03-30

Integrated systems for control of pink bollworm in cotton

A Lawrence Livermore National Laboratory (LLNL) Management Pre-Start Review (MPR) Team was formed to independently verify the operational readiness of Building 368 (B368) Biosafety Level III (BSL-3) Facility to conduct research with biological pathogens and toxins including those considered Select Agents. Review objectives and criteria were developed from the DOE/NNSA and LLNL requirements. These were provided in the Implementation Plan for the Biosafety Level III (BSL-3) Facility Management Pre-Start Review (BSL-3 MPR) at Lawrence Livermore National Laboratory that was reviewed and approved by DOE/NNSA-LSO. The formal part of the LLNL MPR for the BSL-3 Facility was begun in August of 2005 but work on the MPR was stopped in October of 2005 due to the need for LLNL to reassess organizational and operational controls and respond to Centers for Disease Control and Prevention inquiries related to a shipping incident involving select agents. The MPR was restarted in ...

2006-07-25