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At least 613 records · Page 34Linked to original sources

PubMed1980

Value of passive immune hemolysis for detection of heat-labile enterotoxin produced by enterotoxigenic Escherichia coli.

The method of passive immune hemolysis of Evans and Evans (Infect. Immun. 16:604-609, 1977) for detection of heat-labile enterotoxin produced by enterotoxigenic Escherichia coli was modified. A total of 373 strains of E. coli were tested by this method using materials obtained by treating the cells with polymyxin B and rabbit antiserum against cholera enterotoxin, purified by affinity gel column coupled with purified cholera enterotoxin, in N-hydroxyethylpiperazine-N'-2-ethanesulfonic acid buffer (pH 6.7). The results correlated very well with those obtained in an assay with Chinese hamster ovary cells. It is concluded that passive immune hemolysis is useful as a routine clinical method for identifying E. coli strains that produce heat-labile enterotoxin.

Animals↗

PubMed1982

GM1 ganglioside enzyme-linked immunosorbent assay for detection of heat-labile enterotoxin produced by human and porcine Escherichia coli strains.

Human and porcine enterotoxigenic strains of Escherichia coli were cultivated in tryptone-yeast extract medium or brain heart infusion broth and tested for production of heat-labile enterotoxin by the GM1 ganglioside enzyme-linked immunosorbent assay (GM1-ELISA) and the Y1 adrenal cell assay. When testing for enterotoxigenicity by the GM1-ELISA technique, homologous antisera for human and porcine heat-labile enterotoxins had to be used to detect enterotoxigenic strains of human and porcine origin, respectively. This observation indicates a serological difference between the heat-labile enterotoxins produced by human and porcine strains. Furthermore, brain heart infusion broth was found to have an inhibitory effect on detection of enterotoxin both in the GM1-ELISA and in a toxin-binding modification of the Y1 adrenal cell test, but not in the conventional adrenal cell assay.

Animals↗

PubMed1984

Characterization of uterine growth response to cholera toxin in hamsters and test of heat-labile enterotoxin from Escherichia coli.

Cholera toxin (CT) and the heat-labile enterotoxin from Escherichia coli, when injected intraperitoneally into cycling hamsters but not rats or mice, induced a massive uterine growth similar to that normally induced by the implanting blastocyst during pregnancy. CT and heat-labile enterotoxin are the only known agents that have this action in any species. Uterine weight reached a maximal sixfold increase 48 h after injection of CT. Concurrent injection of estrogen, progesterone, and CT increased the maximal response to eightfold and eliminated differences in the response to CT injected on different days of the 4-day hamster estrous cycle. The dose response for CT, heat-labile enterotoxin, and CT plus estrogen plus progesterone was most linear (r greater than 0.93) when the logarithm of uterine weight was plotted against the dose of toxin. The hamster uterine weight response can serve as a simple, highly precise, and highly specific bioassay for CT and heat-labile enterotoxin.

Animals↗

PubMed1986

Evidence for production of an enterotoxin and cholera toxin cross-reactive factor by Aeromonas hydrophila.

The enterotoxins produced by Aeromonas hydrophila were examined for biological activity by the rabbit ileal loop and suckling mouse assays, as well as by elongation of CHO cells. Antigenic evaluation of the culture filtrates from various isolates of A. hydrophila was performed by enzyme-linked immunosorbent assay with anti-cholera toxin and anti-Aeromonas enterotoxin. Heat stability data demonstrated the presence of a heat-labile cholera toxin cross-reactive factor and a heat stable non-cholera toxin cross-reactive enterotoxin. The biological activities of both enterotoxins were heat labile at 56 degrees C for 20 min.

Aeromonas↗

PubMed1986

Antibodies to staphylococcal enterotoxins and toxic shock syndrome toxin 1 in sera of patients and healthy people in Rio de Janeiro, Brazil.

Sera from 33 persons with staphylococcal infections and from 37 healthy persons were surveyed for the presence of antibody to staphylococcal enterotoxins A, B, C, D, and E and toxic shock syndrome toxin 1. Thirty-one (93.9%) of the patients and 35 (94.6%) of the control group had antibodies to one or more of the enterotoxins. The numbers of patients with antibody to the enterotoxins were as follows: A, 8; B, 9; C, 7; D, 17; E, 21; and toxic shock syndrome toxin 1, 11. The numbers of healthy individuals with antibody to the enterotoxins were as follows: A, 6; B, 12; C, 8; D, 27; E, 21; and toxic shock syndrome toxin 1, 9.

Antitoxins↗

PubMed1987

Detection of enterotoxigenic Escherichia coli by colony hybridization with biotinylated enterotoxin probes.

By using biotinylated enterotoxin DNA probes, a method to detect enterotoxigenic Escherichia coli by colony hybridization was developed. The treatment of colonies on nitrocellulose membrane filters with proteinase K and Triton X-100 was essential for obtaining the specific hybridization. A total of 200 E. coli strains isolated from travelers with diarrhea were tested for colony hybridization by using a probe encoding heat-labile toxin (LT) type h. All strains (86 of 86) that produced LT, but none of the non-LT producers, hybridized with 32P-labeled and biotinylated LT type h probes. A total of 36 strains chosen randomly from the 200 isolates were tested for colony hybridization by using heat-stable enterotoxin (ST) probes. All but two strains that hybridized with the 32P-labeled ST type Ia probe also hybridized with the biotinylated ST type Ia probe. All strains that hybridized with the 32P-labeled ST type Ib probe also hybridized with the biotinylated ST type Ib probe. Thus, almost all E. coli strains tested were judged to be the same by colony hybridization with biotinylated or 32P-labeled enterotoxin probes. These results demonstrate that the biotinylated enterotoxin probes are useful in the diagnosis of enterotoxigenic E. coli strains by colony hybridization.

Bacterial Toxins↗

PubMed1976

Studies on the production of enterotoxins by Bacillus cereus.

Evidence is presented for the existence of three distinct enterotoxins detected in concentrated cell-free culture filtrates of selected Bacillus cereus strains. The first was a product capable of stimulating the adenylate cyclase-cyclic-AMP system in intestinal epithelial cells and, possibly through this, causing fluid accumulation in ligated ileal sections ("loops") of young rabbits. This was elaborated by a strain isolated from an incident of diarrhoea and which caused diarrhoea in 6 of 10 monkey feedings. The second was tentatively identified as a factor which caused fluid accumulation in rabbit loops but not, apparently, through stimulation of the adenylate cyclase-cyclic-AMP system; this was elaborated by a strain isolated from raw rice which failed to produce symptoms in eight monkey feedings. Together, the behaviour of these two factors indicates that diarrhoea caused by B. cereus enterotoxin may be a cyclic-AMP-mediated event. The third, here referred to as "pyogenic toxin", caused severe tissue damage in the ileal mucosa and was elaborated by a strain isolated from a brain abscess. A factor produced by a strain isolated from an outbreak of vomiting which caused vomiting in 10 of 24 monkey feedings could bot be detected in tests reported here but appears to be a fourth enterotoxin type. Cytopathic effects in tissue cultures, suckling mouse tests, and assays of glycerol production by fat cells were not found to be of value in the detection of any of the enterotoxins.

Adenylyl Cyclases↗

PubMed1985

Development and application of an enzyme linked immunosorbent assay for Clostridium perfringens type A enterotoxin.

An enzyme linked immunosorbent assay (ELISA) has been developed to quantitate faecal Clostridium perfringens enterotoxin in the investigation of C perfringens food poisoning. The sandwich ELISA could be carried out in 24 h and was sensitive enough to detect as little as 5 ng/g of enterotoxin in faeces. Specificity of the assay was shown by comparing results with those obtained from other standard toxin assays, such as double gel diffusion and counterimmunoelectrophoresis, and by the assay of faecal material from control groups. By means of the ELISA method, 515 faecal samples from 50 separate outbreaks of C perfringens food poisoning were examined, together with 21 food samples from 12 of the outbreaks. A clear distinction was noted between faecal samples collected on the first two days of an outbreak, where 77% were enterotoxin positive, and those specimens collected later than the second day, when only 33% had detectable enterotoxin. The ELISA is recommended as a valuable tool in the investigation of C perfringens foodborne illness.

Clostridium perfringens↗

PubMed1976

Anomalous aggregation of Clostridium perfringens enterotoxin under dissociating conditions.

Polyacrylamide gel electrophoresis of highly purified Clostridium perfringens enterotoxin revealed electrophoretic microheterogeneity of the enterotoxin, apparently because of slight charge differences in the peptides. Detergent gel electrophoresis showed that purified enterotoxin formed high molecular weight aggregates in the presence of both sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide. No conditions capable of inhibiting this phenomenon were found. Although a molecular weight of 35 000 daltons has been reported in the literature, the experimentally determined molecular weight values in the presence of detergents corresponded to multiples of a theoretical subunit molecular weight of 17 500 daltons. Binding studies performed by equilibrium dialysis and ultracentrifugation methods revealed that the enterotoxin bound very small amounts of SDS per gram of protein. The evidence presented indicates possible detergent induced structural alterations of the protein.

Cetrimonium Compounds↗

PubMed1978

Double-antibody radioimmunoassay for staphylococcal enterotoxins A and B.

A sensitive double-antibody radioimmunoassay for staphylococcal enterotoxins A and B is described. The separation of the primary antigen-antibody complex of enterotoxin A and B was achieved with an anti-rabbit gamma globulin from goats. Radioiodinated aggregate fractions of staphylococcal enterotoxins exhibited reduced immunological activity and showed little competition with non-radioactive exterotoxin. The radioimmunoassay was successfully applied for the quantitation of enterotoxins in food.

Bacterial Toxins↗

PubMed1981

Effect of chemical and pharmacological agents on the secretory activity induced by Escherichia coli heat-stable enterotoxin.

The effect of aspirin (ASP), chlorpromazine (CPZ), diphenoxylate (DP), ethylene glycol tetraacetate (EGTA), hydrocortisone (HC), loperamide (LPA), methylprednisolone (MP), phenotolamine mesylate (PTM), propranolol (PR), and trifluoperazine (TPZ) on the secretory activity induced by Escherichia coli heat-stable (ST) enterotoxin in infant mice was studied. LPA and DP, which are used therapeutically for diarrhea, did not inhibit the effect of ST enterotoxin; MP and HC, known inhibitors of cholera enterotoxin, and two adrenergic agents (PR and PTM) had no effect on ST-induced secretory activity. TPZ, EGTA, ASP, and CPZ caused a significant (P less than 0.05) decrease in the secretory activity induced by ST enterotoxin, CPZ, EGTA, and TPZ inhibited secretory activity induced by 8-bromoguanosine 3'5'-cyclic monophosphoric acid (8-BrcGMP), a cGMP analog.

Animals↗

PubMed1983

Primary structure determination of Escherichia coli heat-stable enterotoxin of porcine origin.

The chemical characterization of Escherichia coli heat-stable enterotoxin (ST) is described. The toxin was isolated and purified to homogeneity from the E. coli strain F11 (PI55) of porcine origin. Following quantitative amino acid analysis, the enterotoxin was found to contain 18 amino acids including 6 cysteines, but was devoid of Ser, Val, Met, Ile, Lys, His, and Arg residues. All cysteine residues were found to be involved in disulfide bridges, even though their positions could not be localized. The enterotoxin thus has a molecular weight of 1979 and was shown to be an octadecapeptide with the following sequence: H2N-Asn-Thr-Phe-Tyr-Cys-Cys-Glu-Leu-Cys-Cys-Asn-Pro-Ala-Cys-Ala-Gly-Cys-Tyr- COOH. Its relationship to other known enterotoxins is discussed.

Amino Acid Sequence↗

PubMed1982

Effects of indomethacin, acetazolamide, ethacrynate sodium, and atropine on intestinal secretion mediated by Escherichia coli heat-stable enterotoxin in pig jejunum.

Intraluminal perfusion of pig jejunum with Escherichia coli heat-stable enterotoxin reversed net absorption of water and electrolytes to net secretion. Addition of atropine (2 x 10(-5)M) to the perfusate reduced the secretory response to enterotoxin and enhanced sodium and chloride absorption in control segments. Indomethacin (1.4 x 10(-3)M), acetazolamide (2.2 x 10(-3)M), or ethacrynate sodium (3.1 x 10(-4)M) had no effect. Mucosal disaccharidase activity and Na-K-ATPase activity were not altered by enterotoxin. The results suggest that blockade of cholinergically mediated secretion in the small intestine attenuates the enterosorptive effects of heat-stable enterotoxin and may be useful therapeutically in the management of secretory diarrhea.

Acetazolamide↗

PubMed1982

Effects of epinephrine, clonidine, L-phenylephrine, and morphine on intestinal secretion mediated by Escherichia coli heat-stable enterotoxin in pig jejunum.

Perfusion of pig jejunum with Escherichia coli heat-stable enterotoxin (strain 1261) reversed net absorption of water and electrolytes to net secretion. Addition of the alpha-adrenergic agonists clonidine (5 X 10(-7) M) or L-phenylephrine (5 X 10(-6) M), or the opiate agonist morphine (3.6 X 10(-6) M) to the perfusate reduced the secretory response to enterotoxin and stimulated absorption in normal jejunum. Epinephrine (5 X 10(-5) M) did not stimulate absorption in controls but reduced chloride loss in the presence of enterotoxin. Mucosal sodium--potassium adenosine triphosphatase was unchanged but disaccharidase activity was decreased in the presence of enterotoxin. The results suggest that alpha-adrenergic agonists and opiate agonists may exert an antidiarrheal action by increasing net transport across intestinal epithelium.

Animals↗

PubMed1990

The effects of enterotoxins and short-chain fatty acids on water and electrolyte fluxes in ileal and colonic loops in vivo in the rat.

The effect of cholera toxin (CT) and Escherichia coli heat-stable enterotoxin (ST) on the ileum and colon was examined in vivo in the rat in an attempt to clarify the effects of enterotoxins on colonic mucosa and to determine if these effects were influenced by short-chain fatty acids (SCFA). Both CT and ST induced similar changes in water and electrolyte fluxes, and the magnitude of these changes in loops of colon was similar to that observed in loops of ileum. The addition of luminal SCFA, acetate, propionate and butyrate did not influence the effect of either toxin in loops of ileum. However, in loops of colon exposed to CT, luminal butyrate (40 mM) largely reversed the effect of CT by converting net water secretion (mean +/- SE, -363 +/- 154 nl.cm-2.min-1) to net water absorption (470 +/- 194 nl.cm-2.min-1) and by significantly reducing the net secretion of sodium ions. In loops of colon exposed to ST, similar effects were observed although net water secretion (-784 +/- 114 nl.cm-2.min-1) was only partially reversed by butyrate (-318 +/- 102 nl.cm-2.min-1). In contrast to butyrate, acetate and propionate did not influence changes in colonic fluxes of water and sodium induced by enterotoxins. Oxidation of butyrate and glucose was observed to be depressed in colonocytes pre-exposed to CT but not to ST. In this model, colonic secretion induced by enterotoxins is similar to that observed in the ileum but differs from ileal secretion in its modulation by luminal butyrate.

Animals↗

PubMed1999

Prevalence of genotypes for fimbriae and enterotoxins and of O serogroups in Escherichia coli isolated from diarrheic piglets in Korea.

Polymerase chain reaction for 4 fimbriae (F4, F5, F6, F41), 2 heat-stable enterotoxins (STa, STb), and 1 heat-labile enterotoxin (LT) were performed on 400 Escherichia coli isolates to determine their genotype prevalence among enterotoxigenic E. coli isolates from preweaned pigs with diarrhea in the Republic of Korea. A total of 200 of the 400 E. coli isolates were also selected for characterization of the O serogroup. Of these 200 isolates, serogroup could be determined in 139 (69.5%) but not in 61 isolates (30.5%). Isolates of serogroup O101 were the most common, followed in descending order by 08, 020, 0162, 0141, and 0149. Ninety-seven (24.3%) of the 400 E. coli isolates carried genes for at least 1 of the entertoxins or fimbrial adhesins. Of these 97 isolates, 27 carried genes for at least 1 of the fimbrial adhesins and entertoxins. Sixty-six percent of the isolates that carried fimbrial adhesin genes carried genes for at least 1 of the enterotoxins, and 71% of the isolates that carried enterotoxin genes carried genes for at least 1 of the fimbrial adhesins. Genes for the F6 fimbriae were detected in 6% of the E. coli isolates, and F4+, F41+, and F5+ genes were detected in 4.3%, 3.3%, and 2% of the isolates, respectively. Genes for STa, STb, and LT were detected in 10%, 8.5%, and 4.3% of the isolates, respectively. The 6 major genotypes observed in this study (in decreasing order) were F6+, STb+, F41+, STa+STb+, F6+STa+, and STa+.

Amino Acid Sequence↗

PubMed1983

Interaction between bovine casein and V. cholerae enterotoxin in the rabbit ileal loop.

Secretory IgA from human breast milk neutralizes cholera enterotoxin in the rabbit ileal loop system. No similar protection by purified bovine milk proteins could be demonstrated; however, one bovine milk protein, casein, had a deleterious effect on intestine exposed to very small quantities of enterotoxin. Highly purified cholera toxin (10 or 100 ng) was incubated with bovine protein solutions for 60 min at 37 degrees C. One-milliliter aliquots were then injected into prepared rabbit intestine loops. The animals were sacrificed at 18 h and the intestinal loop contents were aspirated, and a volume to length of loop ratio (V/L) was determined. The activity of 100 ng of toxin was not enhanced by the majority of bovine milk proteins, but bovine casein caused a 14-40% increase in the fluid production (V/L of casein + toxin versus toxin, 1.05 versus 0.92 and 1.82 versus 1.30). All of the bovine proteins but casein inhibited the action of low dose enterotoxin. Bovine casein caused a 78-90% increase in fluid production by loops exposed to a suboptimal toxin dose (10 ng) (V/L of casein + toxin versus toxin, 1.12 versus 0.63 and 0.95 versus 0.50). Virtually all of this enhancement of enterotoxin fluid response resided in the purified alpha-casein fraction.

Animals↗

PubMed1986

Human and bovine milk: comparison of ganglioside composition and enterotoxin-inhibitory activity.

Milk gangliosides inhibit Vibrio cholerae enterotoxin and Escherichia coli heat-labile enterotoxin. Human milk gangliosides showed considerably higher enterotoxin-inhibitory activity compared to bovine and formula milk gangliosides as measured in vitro by enzyme-linked immunosorbent assay and in vivo in rabbit small bowel loops. While gangliosides from less than 1 ml human milk inhibited 0.1 microgram choleratoxin in vitro and in vivo, five to 10 times higher amounts of bovine milk gangliosides were necessary to achieve similar results. Analysis of the ganglioside composition in human, bovine, and bovine milk-based formula milk showed that the ganglioside patterns in human and bovine milk differed markedly. The ganglioside patterns of bovine milk and formula milk appeared identical. In human or bovine milk, the total amount of gangliosides was 11 mg/liter compared to 6 mg/liter in formula milk. The predominating ganglioside in human milk, monosialoganglioside 3 (74% of total gangliosides), was only a minor component (3%) of bovine milk gangliosides. Disialoganglioside 3 represented 80% of bovine milk gangliosides compared to 25% of the human milk gangliosides. Trace amounts of monosialoganglioside 1 were detected in human, as well as in bovine, milk by a sensitive high performance thin-layer chromatography immunoassay. The monosialoganglioside 1 content in human milk was 10 times higher than in bovine milk. We conclude that the higher nonimmunoglobulin enterotoxin-inhibitory activity in human milk compared to bovine milk is associated with the differences in the ganglioside fraction.

Animals↗