SEARCH · PubMed Health

Results for “ENTEROTOXINS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 667 records · Page 37Linked to original sources

PubMed1981

Nicotinic acid inhibits enterotoxin-induced jejunal secretion in the pig.

The use of nicotinic acid for preventing intestinal secretion caused by cholera toxin and by the heat-stable enterotoxin of Escherichia coli has been investigated in the weanling pig. Secretory effects were measured in ligated jejunal loops of halothane-anesthetized pigs by dilution of a nonabsorbable marker added to the loop fluid. Different routes of administration and different initial pH values for nicotinate solutions were studied to determine optimal conditions for secretory inhibition. The neutral sodium salt of nicotinic acid had no significant antisecretory activity under any conditions used in these trials. Inhibition of secretion was most effective with partly neutralized nicotinic acid at pH 4.5 added directly to loops containing enterotoxin. Net fluid secretion induced by cholera toxin or heat-stable enterotoxin of E. coli was prevented by this treatment. Reversal of secretion was not accompanied by any measurable changes in cyclic nucleotide concentration in intestinal mucosa. Nicotinic acid antagonism of a secretory step common to cholera toxin and heat-stable enterotoxin of E. coli but subsequent to cyclic nucleotide involvement is indicated by these data.

Animals↗

PubMed1981

Antibodies to heat-labile Escherichia coli enterotoxins in human milk and sera. A study of Ethiopian and Swedish mothers and their children.

Maternal serum and cord blood from 50 Ethiopian, 10 Costa Rican and 20 Swedish newly delivered mothers and their babies was examined for the presence of antibodies against heat labile (LT) enterotoxin from a human strain of E. coli. 96% of the Ethiopian, 80% of the Costa Rican and 30% of the Swedish mothers and infants had detectable antibody levels. The titres were significantly higher in the Ethiopian material. Furthermore, antibody titres to E. coli enterotoxin were determined in breast milk collected from Ethiopian mothers at 48 h and at 1 month after delivery. One third of these mothers had detectable levels of antibodies in samples from early lactation. Experiments performed with LT enterotoxin from another human and with LT from a porcine E. coli strain confirmed the results. Neutralization tests with cholera enterotoxin as antigen were all negative in sera and milk samples from all these groups. The material has been collected in three different geographical areas which are nonendemic for cholera.

Antibodies, Bacterial↗

PubMed1982

Transfer of drug resistance and enterotoxin production in porcine Escherichia coli strains and relationship between K88 antigen and raffinose (melitose) fermentation.

To obtain an indication of the frequency of drug resistance together with enterotoxin production in a select group of porcine E coli strains, those enterotoxigenic strains that were resistant to specific antimicrobial agents were mated as donors with nonenterotoxigenic E coli strains that were sensitive to these drugs as recipients. Seven of the 17 strains tested transferred drug resistance by direct mating. These 7 strains also transferred drug resistance following mobilization. The frequency of recipient conversion was increased following mobilization, as compared with the frequency of conversion resulting from direct mating. In 2 of these strains, enterotoxin production was transferred together with drug resistance. Eight strains transferred drug resistance only after mobilization, and in 2 of these, enterotoxin production was transferred simultaneously with resistance to the antimicrobial agents. In 2 of the 17 strains tested, neither transfer of drug resistance nor transfer of enterotoxin production could be achieved by direct mating or after mobilization. Thirty-nine porcine E coli strains were tested for K88 antigen production and raffinose (melitose) fermentation with a view toward determining whether raffinose fermentation could be used as a diagnostic tool for the detection of the K88 antigen. In 11 of the K88-positive strains tested, only 7 fermented raffinose. In the remaining 28 K88-negative strains, 17 fermented raffinose. Consequently no meaningful correlation existed between these 2 properties of porcine enterotoxigenic E coli strains.

Animals↗

PubMed1982

Myoelectric effects of Clostridium difficile: motility-altering factors distinct from its cytotoxin and enterotoxin in rabbits.

Clostridium difficile is a bacterium that causes antibiotic-associated pseudomembraneous enterocolitis. This bacterium produces a cytotoxin that induces tissue culture assay positivity and an enterotoxin that causes in vivo mucosal injury. In previous studies we have described two altered myoelectric patterns in response to certain diarrheagenic organisms in an in vivo rabbit model. The first pattern was called the migrating action potential complex and is associated with noninvasive agents; the second pattern was called repetitive bursts of action potentials and is characteristic of invasive or cytolytic agents. In this study, we evaluated the effects of purified cytotoxin (2.5-3.75 micrograms) and enterotoxin (140 micrograms) from C. difficile on the myoelectric activity in isolated ileal loops in New Zealand White rabbits. These observations in myoelectric activity were correlated with the results of similar studies by using the crude culture filtrates from C. difficile, or the products of Amicon XM50 filtration of its culture supernatant resulting in a high molecular weight product (0.3 mg protein/ml) and a low molecular weight product (0.57 mg protein/ml). Monopolar silver-silver chloride electrodes were used to record all myoelectric activity for an 8-h period. The animals were then killed, and tissue obtained from the ileal loops was histologically evaluated. Crude culture filtrates of C. difficile induced 7.0 migrating action potential complexes/hour and 6.8 repetitive bursts of action potentials/hour. Saline controls induced no migrating action potential complexes and 0.1 repetitive bursts of action potentials/hour. The high molecular weight filtration product obtained from the culture supernatant of C. difficile induced significantly more repetitive bursts of action potentials (41.1/h) than all agents studied. The purified cytotoxin or enterotoxin induced no migrating action potential complex activity and minimal repetitive bursts of action potential activity (0.9/h and 0.6/h, respectively). These values were not different from the saline controls; however, only the enterotoxin and the high molecular weight filtration product caused mucosal damage. These studies suggest that C. difficile produces a heat-labile substance or substances that alter the motility of the small intestine independent of the proteins responsible for in vivo tissue damage and cytotoxin assay positivity.

Action Potentials↗

PubMed1982

Isolation of Salmonella wien heat-labile enterotoxin.

An enterotoxic activity has been identified in culture filtrates of Salmonella wien. The enterotoxin causes fluid accumulation in rabbit ligated ileal loops, firm induration and erythema in rabbit skin and morphological alteration in chinese hamster ovary (CHO) cell cultures; it was revealed by treatment with calcium phosphate gel, and purified on DEAE-Sephadex A-50 and BioGel A-1.5 m. The enterotoxic activity was eluted from the BioGel column in two peaks. Approximately 50-70% of the enterotoxic activity of the first peak, corresponding to the excluded volume, was resistant to heating at 75 degrees C for 30 min, while the activity of the second peak was completely destroyed by this treatment. From the heat-labile peak a protein, in homogeneous form, was isolated exploiting its affinity towards agarose gel filtration media. This protein, with enterotoxic activity was also present as shown by SDS-PAGE, in the first peak, eluted from the Bio-Gel column, where it appears to be closely associated with cell wall or membrane components and thus protected from heat denaturation. The isolated enterotoxin is stable in alkaline conditions but it is sensitive to acidic pH values; moreover, it stimulates adenylate cyclase in cell culture systems. Thus, it appears to possess properties similar to both cholera toxin and the heat-labile enterotoxin of Escherichia coli. These results indicate that the enterotoxin is a protein in nature and it is postulated that it may participate in the pathogenesis of S. wien infection.

Adenylyl Cyclases↗

PubMed1993

Phage-related conversion of enterotoxin A, staphylokinase and beta-toxin in Staphylococcus aureus.

The conversion of enterotoxin A, staphylokinase and beta-toxin in Staphylococcus aureus is related with lysogeny stage. Bacteriophages able to convert enterotoxin A were used for lysogenization of the standard NCTC 8325-4 strain. Lysogenic, enterotoxigenic derivatives of this strain were characterized. The conversion of enterotoxin A was obtained in 7 examined derivatives, the conversion of enterotoxin A and staphylokinase at the same time was obtained in one case and the loss of beta hemolysin production ability was observed in all of 8 examined derivatives of the NCTC 8325-4 standard strain.

Bacterial Toxins↗

PubMed1976

Etiologic diagnosis of diarrheal disease of calves: frequency and methods for detecting enterotoxin and K99 antigen production by Escherichia cola.

Escherichia coli isolated from calves in Minnesota and Montana were tested for enterotoxigenicity via bio-assay of cell-free broth culture fluid and for K99 antigen via a serum agglutination test. Infant mice were used to assay for heat-stable enterotoxin (ST), and adrenal cells in culture were used to assay for heat-labile enterotoxin (LT). Forty-six of the 345 E coli isolates produced ST enterotoxin, but none produced LT enterotoxin. Thirty-five of the 46 enterotoxigenic isolates had K99 antigen, and only 9 of 66 nonenterotoxigenic isolates so tested had this antigen. The enterotoxigenicity of 28 additional E coli isolates known or suspected to be calf enteropathogens and provided by investigators from 3 different laboratories was also tested. All isolates from 2 laboratories produced ST but not LT. All isolates from the 3rd laboratory produced LT but not ST. Escherichia coli organisms that were positive in the infant mouse assay also caused positive ligated, jejunal-loop responses in calves and in 9-day-old (but not in 5-week-old) pigs. It was concluded that the infant mouse and adrenal cell tests for ST and LT, combined with the agglutination test for K99, would be useful in the diagnosis of enteric enterotoxic colibacillosis of calves.

Agglutination Tests↗

PubMed1994

A cytotoxicity assay for Clostridium spiroforme enterotoxin in cecal fluid of rabbits.

Clostridium spiroforme enterotoxin-mediated diarrhea can be a common cause of mortality among weanling age rabbits. Definitive diagnosis of this disorder requires detection of the causative enterotoxin. Using filtered cecal supernatant from necropsy specimens, antibodies to C. spiroforme and its products and Vero cells, a cytotoxicity assay was performed on 22 rabbits with clinical signs and lesions consistent with C. spiroforme enterotoxin-mediated diarrhea. A cytotoxic effect was detected, generally within 4 h, in 18 of 22 rabbits. The cytotoxic effect was blocked by preincubation of the cecal material with antibodies to C. spiroforme and its products. Culture of cecal contents and smears of cecal contents identified C. spiroforme in 10/22 and 12/22 cases, respectively. This cytotoxicity assay provided a rapid and sensitive method for diagnosing C. spiroforme enterotoxin-mediated diarrhea.

Animals↗

PubMed1975

[Effect of thermal treatment on the properties of staphylococcal enterotoxin type A].

Thermal treatment of staphylococcus enterotoxin of type A at the stage of the cultural fluid failed to influence the character of the enterotoxin purification under the given conditions. In both cases the amount of the removed nitrogen components constituted about 97%. The purified preparations of the staphylococcus enterotoxin of type A differed from one another by the data of electrophoresis and ultracentrifugation and also by the antigenic composition. Under the action of thermal treatment staphylococcus enterotoxin of type A changed its antigenic properties and lost some of its biological activity.

Animals↗

PubMed1993

A cholera-coli related enterotoxin production by different Shigella species.

A cholera-coli related enterotoxin production was studied in 50 different Shigella isolates from cases of childhood diarrhoea. Four out of 6 Sh. dysenteriae, 18/37 Sh. flexneri and 2/4 Sh. sonnei were found to be enterotoxin producers by RIL test. All strong RIL positive strains were isolated from cases of severe diarrhoea, indicating the association of enterotoxin production and severity of acute diarrhoea. Two major protein bands were observed in SDS-PAGE and W.B. EIA assay in all positive RIL extracts. These immuno-reactive bands were at 31 kDa and 14 kDa positions resembling A-B subunit structure of cholera-coli family of enterotoxins.

Animals↗

PubMedDate not supplied

Visual screening with enzyme immunoassay for staphylococcal enterotoxins in foods: collaborative study.

Selected foods containing 4-10 ng each of a mixture of Staphylococcus aureus enterotoxin serotypes A-E were tested by 15 collaborators. An enzyme-linked immunosorbent assay (EIA) was used with polyvalent antisera to these serotypes in a polyclonal antibody double "sandwich" configuration. Controls were free of toxin. Foods (25 g test samples) were homogenized with Tris (0.25 M, pH 8.0) and centrifuged. The food extract was filtered through cotton and mixed with sample additive. For the EIA, 200 microL aliquots of the treated extracts were added to previously washed microtiter wells coated with antibody to staphylococcal enterotoxin serotypes A-E. Wells were washed and treated with the polyvalent antisera (A-E)-enzyme conjugate, and then washed again. Substrate was added, and wells were incubated. After incubation, stop solution was added. Results were determined visually and by measuring absorbance using a microtiter plate reader. In foods containing enterotoxin, bluish-green color was developed (positive result). Test solutions with absorbances > 0.200 were considered positive; those with absorbances < or = 0.200 were negative. The method is sensitive and specific, and allows the rapid assay of staphylococcal enterotoxins in foods without differentiating their serotypes. The method has been adopted first action by AOAC INTERNATIONAL.

Color↗

PubMed1976

Highly sensitive determination of Bacillus cereus exo - enterotoxin using the method of aggregate haemagglutination.

The possibility has been demonstrated of using the method of aggregate-haemagglutination for the detection of B. cereus exo-enterotoxin in both food products and culture media. It has been established that 0.004 mug/ml of enterotoxin can be detected by this method. The applied antisera to B. cereus enterotoxin did not yield cross reactions with enterotoxins produced by E. coli, Cl. perfringens, St. aureus, V. cholerae or Sh. dysenteriae.

Animals↗

PubMed1976

[Obtaining purified staphylococcal enterotoxin type B].

The authors elaborated a method of purification of staphylococcus enterotoxin, type B, consisting of three stages: the first stage--lyophilization and dialysis of the culture fluid against distilled water for 36 hours, the second stage--precipitation of dialyzed preparation with 2 volumes of ethanol at --15 degrees C, and the third stage--gel-chromatography of the enterotoxin preparation precipitated with alcohol on a column with Sephadex G-100 in a 0.015 M solution of NaCl (pH 7.0). Preparation isolated by the mentioned method possessed enterotoxic activity in a dose of 0.015 mg of protein per 1 kg of cat weight; by antigenic composition it represented a two-component system. In immunization of rabbits with a purified enterotoxin preparation an antiserum with the prevalence of antibodies to enterotoxin, type B, was obtained.

Enterotoxins↗

PubMed1998

Cooperative activation of TCRs by enterotoxin superantigens.

Staphylococcus enterotoxin superantigens are potent T cell activators. To gain new insights into the mechanism of T cell activation induced by these superantigens, we investigated the recruitment of signaling molecules in this process. Here, we show that enterotoxin superantigen activation can be transmitted to TCR-CD3 complexes that did not interact with their ligand. Indeed, by studying cells expressing two distinct TCRs, we found that enterotoxin superantigens induced tyrosine phosphorylation of TCRzeta subunits, the recruitment and tyrosine phosphorylation of the protein tyrosine kinase ZAP-70, and an increase in protein tyrosine kinase activity of both directly stimulated and unstimulated TCR-CD3 complexes. As the involvement of unstimulated TCR-CD3 complexes in signal transduction would increase the number of signaling molecules and, therefore, the efficiency of T cell activation, these data provide a novel explanation for the ability of enterotoxin superantigens to potently activate T lymphocytes.

Cell Line↗

PubMed1980

Mechanism of action of Clostridium perfringens enterotoxin. Effects on membrane permeability and amino acid transport in primary cultures of adult rat hepatocytes.

Purified enterotoxin from the bacterium Clostridium perfringens rapidly decreased the hormonally induced uptake of alpha-aminoisobutyric acid in primary cultures of adult rat hepatocytes. At 5 min after toxin addition the decrease in alpha-aminoisobutyric acid uptake appeared not due to increased passive permeation (estimated with L-glucose) or to increased alpha-aminoisobutyric acid efflux. When short uptake assay times were employed a depression of alpha-aminoisobutyric acid influx was observed in toxin-treated hepatocytes. The depression of alpha-aminoisobutyric acid influx was correlated with a rapid increase in intracellular Na+ (estimated using 22Na+) apparently effected by membrane damage. In contrast, the uptake of cycloleucine in the presence of unlabeled alpha-aminoisobutyric acid (assay for Na+-independent amino acid uptake) by hepatocytes treated with toxin for 5 min was decreased to only a small extent or not at all depending upon experimental design. At later times, C. perfringens enterotoxin increased the exodus of L-glucose, 3-O-methylglucose and alpha-aminoisobutyric acid from pre-loaded cells indicating that the toxin effects progressive membrane damage. When enterotoxin was removed by repeated washing after 5--20 min the decay of alpha-aminoisobutyric acid uptake ceased and appeared to undergo recovery towards the hormonally induced control level. The degree of recovery of alpha-aminoisobutyric acid uptake was inverse to the length of time of exposure to toxin. Adding at 10 min specific rabbit antiserum against C. perfringens enterotoxin without medium change also reversed the effect of toxin on increased intracellular 22Na+, and on the exodus (from preloaded cells) of alpha-aminoisobutyric acid, L-glucose, and 3-O-methylglucose.

Amino Acids↗

PubMed1980

Adenosine diphosphate-ribosylation of adenylate cyclase catalyzed by heat-labile enterotoxin of Escherichia coli: comparison with cholera toxin.

The heat-labile enterotoxin of Escherichia coli, like cholera toxin, activates adenylate cyclase by catalyzing the transfer of adenosine diphosphate-ribose from HAD+ (oxidized nicotinamide adenine dinucleotide) to the guanyl nucleotide-dependent regulatory component of the cyclase. A preparation of enterotoxin that had been released from E. coli following exposure to polymyxin B and then partially purified was found to contain two enzymatically active peptides, one of about 29,000 and the other of about 24,000 daltons, which correspond in molecular size to the enzymatically active subunit A and fragment A1 of cholera toxin, respectively. As with cholera toxin, the enzymatic activity of E. coli enterotoxin was elevated by incubation with sodium dodecyl sulfate to release active peptides. Treatment with dithiothreitol, however, had no effect. Dithiothreitol activates subunit A of cholera toxin by reducing an internal disulfide bond, but no corresponding bond appears to be present in the partially purified E. coli enterotoxin.

Adenosine Diphosphate Ribose↗

PubMed1999

Production and characterization of monoclonal antibodies against the hemolysin BL enterotoxin complex produced by Bacillus cereus.

A total of five hybridoma cell lines that produced monoclonal antibodies against the components of the hemolysin BL (HBL) enterotoxin complex and sphingomyelinase produced by Bacillus cereus were established and characterized. Monoclonal antibody 2A3 was specific for the B component, antibodies 1A12 and 8B12 were specific for the L(2) component, and antibody 1C2 was specific for the L(1) protein of the HBL enterotoxin complex. No cross-reactivity with other proteins produced by different strains of B. cereus was observed for monoclonal antibodies 2A3, 1A12, and 8B12, whereas antibody 1C2 cross-reacted with an uncharacterized protein of approximately 93 kDa and with a 39-kDa protein, which possibly represents one component of the nonhemolytic enterotoxin complex. Antibody 2A12 finally showed a distinct reactivity with B. cereus sphingomyelinase. The monoclonal antibodies developed in this study were also successfully applied in indirect enzyme immunoassays for the characterization of the enterotoxic activity of B. cereus strains. About 50% of the strains tested were capable of producing the HBL enterotoxin complex, and it could be demonstrated that all strains producing HBL were also highly cytotoxic.

Animals↗

PubMed1967

Effect of staphylococcal enterotoxin B on the electroencephalogram of monkeys.

A highly purified preparation of staphylococcal enterotoxin B was administered intravenously, 1 mg/kg, to rhesus monkeys. Electroencephalograms (EEG) were recorded from electrodes attached to the skin or implanted on the dura. The dose of toxin employed consistently produced a sequence of vascular collapse followed by death; in control studies, animals were bled periodically to produce a similar pattern of shock. Regardless of the time to death following administration of the enterotoxin, there were essentially no changes from base line EEG patterns until shortly before death. With the development of preterminal severe shock, there was a marked decrease in EEG wave frequency and an initial increase in amplitude. The latter diminished progressively to produce an isoelectric tracing immediately prior to death. This could be reversed for a brief period by epinephrine. An identical sequence of EEG changes was observed during the terminal period of hemorrhagic shock. It is postulated that cerebral anoxia, caused by inadequate blood flow, is the primary cause of the altered EEG patterns that accompany enterotoxin toxicity. In this respect, staphylococcal enterotoxin B produces changes apparently similar to bacterial endotoxin but distinctly different from the EEG effects reported after botulinum toxin, anthrax toxin, or rattlesnake and cobra venom.

Animals↗