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At least 397 records · Page 22Linked to original sources
PubMed1959

Some pharmacological properties of the alpha-toxin of staphylococcus pyogenes.

The alpha-toxin of Staphylococcus pyogenes produced a slowly developing contracture of isolated preparations of rabbit jejunum and of guinea-pig ileum which persisted after thorough washing and left the gut unresponsive to further doses of alpha-toxin or of acetylcholine. After incubation with antitoxin, the alpha-toxin no longer produced a contracture. Antitoxin only prevented the alpha-toxin response if added to the bath fluid before but not after the alpha-toxin. Certain drugs reduced the alpha-toxin contracture when added to the bath fluid before or after the alpha-toxin, but the contracture reappeared on washing. Papaverine abolished the contracture and pethidine was only slightly less active. Mepyramine, amyl nitrite, caffeine, aminophylline, adrenaline and ephedrine partly reduced the contracture. Hexamethonium, cocaine, tubocurarine and gallamine had no effect. The effect of atropine was only small. The gut-stimulant activity/haemolytic unit of two alpha-toxin samples differed greatly; this difference did not appear to be due to activity of impurities. The implications of these observations are discussed.

Acetylcholine↗
PubMed1984

The titration of tetanus antitoxin III. A comparative evaluation of indirect haemagglutination and toxin neutralization titres of human sera.

The tetanus antitoxin titres of 174 serum samples from healthy adults were determined by a standardization indirect haemagglutination test (IHA) and the conventional toxin neutralization (TN) test. The serum samples were titrated by the IHA test using glutaraldehyde-fixed and toxoid sensitized sheep erythrocytes before and after the treatment of the sera with 2-mercaptoethanol (2-ME). The IHA method has been found to be very sensitive and specific for the estimation of tetanus antitoxin in human sera. The IHA titres before the treatment of the sera with 2-ME were generally about four times higher than the TN titres and the correlation coefficient between these titres was 0.94. The IHA titres after the treatment of the sera with 2-ME were in good agreement with the TN titres and there was no statistically significant differences between the titres by the two methods. The tetanus antitoxin titres of 50% of the sera were below the minimum protective titres of tetanus antitoxin (0.01 IU/ml). In 19.5% of the sera the antitoxin level (IU/ml) ranged from 0.01 to 0.1, in 20.1% from 0.1 to 1.0 and in 10.4% from 1.0 to 10.0.

Hemagglutination Tests↗
PubMed1976

The standardization of Cl. perfringens antigens and antisera.

The preparation of laboratory standard antitoxins against Cl. perfringens beta and epsilon toxins is described. These antitoxins are suitable for the quantitative determination of the corresponding antigens by means of the flocculation test. The flocculation test was, however, shown to be more suitable for determining the antigenic value of fresh toxoid rather than toxoid stored without neutralization of excess formalin. A maximal immunity response to alum-precipitated epsilon toxoid was obtained in sheep with two injections containing 90 Lf per dose. The interval between these injections may vary from 2 to 6 weeks. The serum-antibody titres after the primary and secondary injections or after a booster dose given before 12 months after the primary injection did not remain above the protective level in most of the sheep injected for longer than about 5 months. When a sound basic immunity is established the degree of protection following on a booster dose given 12 months later is complete for at least 12 months. An alum-precipitated vaccine containing 25 Lf epsilon toxoid per dose is adequate. The decline in the serum-antibody titre during the first year of vaccination could be eliminated by the use of the antigen in water-in-oil emulsion. Lambs from immune dams were protected for at least up to 13 weeks of age. A satisfactory level of circulating antitoxin against Cl. perfringens beta toxin could be produced in ewes by vaccinating them with APT containing 6.25 Lf beta toxoid per dose. The primary and secondary injections could be separated by 2, 3, 4 or 5 weeks without changing the end result. A booster dose given 2 months before parturition was satisfactory.

Animals↗
PubMed1983

Studies on the antibody composition and neutralizing activity of tetanus antitoxin sera from various species of animals in relation to the antigenic substructure of the tetanus toxin molecule.

On the basis of the antigenic substructure of tetanus neurotoxin, the antitoxin compositions of horse, rabbit and human tetanus antitoxin sera, in terms of their contents of antibodies against four antigenic determinant groups (alpha, beta-1, beta-2 and the "topographic" determinant group gamma) so far known for the toxin were studied by quantitative precipitation reactions using purified toxin, complementary fragments alpha, beta and fragment beta-1 (a subfragment of fragment beta) of the toxin. The antitoxin antibody composition varied slightly depending on the antiserum preparation. In addition, different patterns of antitoxin antibody composition and toxin-neutralizing ability, characteristic of horse, rabbit and man were found: horse antitoxin sera contained all four kinds of antibodies and horse anti-gamma showed low toxin-neutralizing ability, while human antisera lacked anti-alpha and had anti-gamma with high neutralizing activity but contained anti-beta-1 with no detectable neutralizing activity. Rabbit sera showed an intermediate pattern between those of horse and human sera. In all antisera, antibodies against determinants on the isolated fragment beta account for approximately 80-50 percent of the total precipitable antibodies and anti-beta-2 antibody was invariably present. Immunodiffusion analyses showed that the antitoxin compositions of mouse and guinea pig antisera resembled those of human antisera. In mice, fragment beta was almost as efficient as whole toxin toxoid in eliciting a protective immune response on an equal weight basis, whereas fragments beta-1 and alpha were both relatively poor antigens.

Animals↗
PubMed1983

Tetanus toxin inhibits the evoked outflow of an inhibitory (GABA) and an excitatory (D-aspartate) amino acid from particulate brain cortex.

In order to elucidate the mode of action of tetanus toxin, particles from rat forebrain were preloaded with tritiated GABA or D-aspartate, pre-incubated with tetanus toxin and then depolarized with K+, either in a batch procedure or by superfusion. The toxin depresses, but does not abolish, the evoked outflow of both amino acids in either system. Omission of Ca2+ decreases the outflow in the batch procedure by about 40%. The remaining outflow of either amino acid is insensitive to tetanus toxin, whereas the Ca2+ dependent outflow is completely inhibited. Antitoxin neutralizes the toxin but does not reverse its in vitro effects, once manifest. The toxin effects increase with time and temperature of pre-incubation. Pretreatment of the particles with V. cholerae neuraminidase, which is known to convert the long-chain gangliosides quantitatively into GM1, does not decrease the sensitivity to tetanus toxin. Besides particles from rat brain, those from chicken, but not those from frog brain, are toxin-sensitive when tested for GABA outflow in the batch procedure. Frog brain does not yield the typical ganglioside pattern, and also does not measurably bind 125I-tetanus toxin. The homoexchange diffusion of GABA, but not of D-aspartate, is slightly facilitated by tetanus toxin. We confirmed that tetanus toxin slightly inhibits the uptake of GABA, whereas that of D-aspartate is not measurably influenced. The accumulation, driven by a Na+/K+ gradient, of GABA into membrane vesicles from rat cortex is not affected by tetanus toxin. The present data support the hypothesis that tetanus toxin influences a process involved in the outflow of many transmitters, both excitatory and inhibitory.

Animals↗
PubMed1975

Chemical modulation of diphtheria toxin action on cultured mammalian cells.

Ammonium chloride (4 times 10-3 M) rendered HEp-2 monolayers completely insensitive to the action of diphtheria toxin, as measured by de novo protein synthesis. Total protection was observed even with large amounts of toxin (400 minimum lethal doses/ml). Ammonium chloride did not reduce toxicity by direct action on the protein, nor did it prevent the adsorption of toxin to the cell membrane. Although the ammonium salt did not block the initial interaction between cell and toxin, it did maintain the toxin at a site amenable to neutralization with antitoxin. Surface-adsorbed toxin was inactivated by cellular enzymes or alternatively was desorbed from the membrane during a 12-h incubation in the presence of ammonium chloride. In addition, ammonium chloride provided protection to both toxin-sensitive guinea pig peritoneal macrophages and a partially toxin-resistant strain of HEp-2 cells. Sodium arsenite was effective in protecting cell monolayers from the action of diphtheria toxin; unlike ammonium chloride, its action was not dependent upon continued incubation with cells during exposure to toxin. Inhibitors of energy metabolism abolished toxin action either totally (sodium fluoride) or partially (dinitrophenol and sodium cyanide). Inhibitors of cellular proteases, on the other hand, did not modify toxin activity. The ability of several modifiers of membrane function to alter expression of toxicity for HEp-2 cells was also examined. One compound known to enhance endocytic activity, Tuftsin, had no effect, whereas poly-L-ornithine provided partial protection. Of the two compounds known to alter membrane fluidity, cytochalasin B provided partial protection for HEp-2 cell cultures, whereas colchicine had no effect. Agents that bind to sulfhydryl groups on the cell surface had no apparent effect on toxicity, suggesting that the initial toxin-cell interaction does not involve sulfhydryl groups. Those compounds that provide virtually full protection against the action of diphtheria toxic on cell monolayers (i.e., ammonium chloride, sodium fluoride, and sodium arsenite) had no inhibitory effect on the in vitro enzyme activity associated with fragment A of the toxin.

Ammonium Chloride↗