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At least 235 records · Page 13Linked to original sources
PubMed1989

Pseudomonas aeruginosa extracellular toxicity in infant mice and the protective effect of antitoxin A.

The toxin A-content of crude extracellular preparations from Pseudomonas aeruginosa has been measured by ELISA. Using infant mice as test animal, the toxicity of these preparations was evaluated. The LD 50 in infant mice was determined at 80 ng of purified toxin A in saline. With ten microliters of rabbit antitoxin A serum given together with purified toxin, the LD 50 increased to 2,500 ng. Generally there was no correlation between the LD 50 of the extracellular preparations, their quantity of toxin A as measured by ELISA, and the protective effect of antitoxin A.

ADP Ribose Transferases↗
PubMed1980

Influence of anti-fragment A of diphtheria toxin on passive hemagglutination with antitoxin.

Hemagglutination (HA) and toxin neutralization (TN) tests were used to titrate human and guinea-pig serum specimens taken at various stages of immunization for diphtheria antitoxin. The ratio of HA to TN titers varied significantly depending on the immune status. The ratios and the range of their variations became larger and high values exceeding five were often obtained after repeated booster immunization. Such a high value was proved to be related to the antibody against fragment A (FrA) of diphtheria toxin, since the ratio reduced significantly when anti-FrA was absorbed. Anti-FrA was not produced in children after the basic immunization with diphtheria toxoid and was detected in only one-third of vaccines after the booster injection given after 1 year. It was produced abundantly, however, when booster immunization was repeated. The pattern of production of anti-FrA in guinea pigs was similar to that in humans, when immunized with diphtheria toxoid with adjuvant. No anti-FrA was produced even when the animals were immunized repeatedly with plain diphtheria toxoid.

Animals↗
PubMed1993

Tetanus toxin inhibits depolarization-induced [3H]serotonin release from rat brain cortex synaptosomes.

The effects of tetanus toxin on depolarization-induced [3H]serotonin release from superfused rat brain cortex synaptosomes was investigated. Two hours' preincubation of the synaptosomes with tetanus toxin resulted in a concentration-dependent decrease of K(+)-stimulated release, with an IC50 of about 30 nM (4.5 micrograms/ml); this inhibitory effect was blocked by a previous incubation of the tetanus toxin with antitoxin serum. Tetanus toxin had no effect on reserpine-induced release, a model of Ca(2+)-independent release. These results indicate that tetanus toxin is able to alter the exocytotic machinery of serotoninergic terminals, in agreement with results obtained with other neurotransmitters. They also indicate that serotoninergic terminals possess the receptor for tetanus toxin. These findings are in line with in vivo observations suggesting a role for serotoninergic system in tetanus intoxication.

Animals↗
PubMed1983

Clostridium tetani growth and toxin production in the intestines of germfree rats.

Germfree rats were challenged orally and intrarectally with spores of Clostridium tetani. Although C. tetani spores remained viable in the intestinal tract, they were unable to germinate. Germfree rats were then challenged orally with vegetative cells of C. tetani. Vegetative cells were able to colonize the intestinal tract, replicate, and produce toxin. Tetanus antitoxin, but no tetanus toxin, was detected in the sera of monoassociated rats.

Animals↗
PubMed2005

Stability of EcoRI restriction-modification enzymes in vivo differentiates the EcoRI restriction-modification system from other postsegregational cell killing systems.

Certain type II restriction modification gene systems can kill host cells when these gene systems are eliminated from the host cells. Such ability to cause postsegregational killing of host cells is the feature of bacterial addiction modules, each of which consists of toxin and antitoxin genes. With these addiction modules, the differential stability of toxin and antitoxin molecules in cells plays an essential role in the execution of postsegregational killing. We here examined in vivo stability of the EcoRI restriction enzyme (toxin) and modification enzyme (antitoxin), the gene system of which has previously been shown to cause postsegregational host killing in Escherichia coli. Using two different methods, namely, quantitative Western blot analysis and pulse-chase immunoprecipitation analysis, we demonstrated that both the EcoRI restriction enzyme and modification enzyme are as stable as bulk cellular proteins and that there is no marked difference in their stability. The numbers of EcoRI restriction and modification enzyme molecules present in a host cell during the steady-state growth were estimated. We monitored changes in cellular levels of the EcoRI restriction and modification enzymes during the postsegregational killing. Results from these analyses together suggest that the EcoRI gene system does not rely on differential stability between the toxin and the antitoxin molecules for execution of postsegregational cell killing. Our results provide insights into the mechanism of postsegregational killing by restriction-modification systems, which seems to be distinct from mechanisms of postsegregational killing by other bacterial addiction modules.

Deoxyribonuclease EcoRI↗
PubMed1995

Evidence of the coevolution of a snake toxin and its endogenous antitoxin cloning, sequence and expression of a serum albumin cDNA of the Chinese cobra.

A full-length cDNA of the serum albumin (CSA) of the cobra (Naja naja kaouthia) was cloned from a lambda gt 11 library. It encodes a mature protein of 614 amino-acid residues homologous to the precursor of mammalian serum albumins. The 1 degree and 2 degrees structures of the CSA resemble those of the human variety. The putative toxin binding sites are mainly located in the subdomains IIA and IIIA. The relation between structural homology and function of the serum albumins (SA) is discussed. An analysis of their evolutionary tree revealed that anti-toxicity arose by < 90 amino-acid exchanges. The rate of substitution is much higher in the SA than in cytochrome C, which probably reflects the difference in evolutionary driving forces. The evolutionary period of the SA (6.7 +/- 0.1 M.Y.) significantly exceeds that of hemoglobin (5.8 M.Y.). Eight tripeptides in the nicotinic acetylcholine receptor (ACR), all flanking the putative toxin binding site, are also found in the CSA where they join to form 1 octa-, 1 penta- and 4 tripeptides, thus indicating the concerted evolution of two functionally linked proteins: toxin and antitoxin (CSA).

Amino Acid Sequence↗
PubMed1976

Preparation and evaluation to Clostridium septicum toxoid.

Clostridium septicum was grown under controlled conditions to produce high levels of alpha toxin. The toxin was toxoided and concentrated by ultrafiltration. The toxoided alpha toxin retained immunizing properties. The concentrated toxoid, when formulated on Total Combining Power, in monovalent or multivalent clostridial products, provided protection to rabbits against direct challenge with Cl. septicum spores. The toxoided alpha toxin produced antitoxin levels which exceeded current minima.

Animals↗