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At least 19 recordsLinked to original sources
PubMedDate not supplied

Effect of bacterial toxins in serum on the chromosomes of WI-38.

Two batches of foetal calf serum, free from detectable bacterial, mycotic, mycoplasmal and bovine viral conta mination and possessing good growth-promoting properties induced an abnormally high number of chromatid breaks in WI-38 cells to the extent that the cells were unacceptable as a vaccine substrate. This phenomenon, immediately reversible on changing to a different batch of serum, was unaffected by pasteurisation, suggesting that it was caused by some unidentified toxic factor(s). It was found that the same effect could be brought about by the addition of subcytotoxic concentrations of some bacterial toxins to the culture media. These findings re-emphasise the importance of improved methods for the collection and the maintenance of sterility throughout the processing of such sera, especially when they are intended to be incorporated in media used to establish vaccine substrates.

Bacterial Toxins↗
PubMed1978

Binding of protein chemotactic factors to the surfaces of neutrophil leukocytes and its modification with lipid-specific bacterial toxins.

The binding to neutrophil leukoyctes of human serum albumin (HSA), which is chemokinetic for leukocytes, i.e. influences their rate of locomotion, and of alkali-denatured HSA, which is chemotactic for leukocytes, i.e. influences their direction of locomotion, was studied. Native serum albumin showed low affinity binding to the neutrophil surface. Denatured serum albumin showed saturable binding with a Ka of approximately 1-(6) litres per mole to about 10(6) binding sites per cell. Another protein chemotactic factor, alpha5-casein, gave similar binding. These results exclude that chemotactic reactions to denatured proteins are mediated in a completely non-specific manner and suggest the presence on the cell of a restricted number of defined recognition sites. Binding was reduced following treatment of the cells with either of two lipid-specific bacterial toxins, perfringolysin, the theta-toxin of Clostridium perfringens, an oxygen-labile cholesterol-specific toxin, and Staphylococcus aureus Sphingomyelinase C. Both have previously been shown to reduce chemotactic reactions and both were used at doses which did not reduce cell viability. These results suggest an important, and possiblly direct, role for membrane lipid in the binding sites for chemotactic factors. Visual analysis of the behaviour of perfringolysin-treated neutrophils showed that these cells were still capable of chemotactic locomotion. The cells appeared to be less efficient than normal in detecting chemotactic gradients only when at a distance from the gradient source, a finding which is consistent with reduced binding of the chemotactic factor to the cell surface.

Bacterial Toxins↗
PubMed1979

Clindamycin-associated enterocolitis in guinea pigs: evidence for a bacterial toxin.

Experimental enterocolitis was induced in guinea pigs by intraperitoneal injection of clindamycin. Specimens of feces were collected daily in phosphate-buffered saline (pH 7.0) and pooled every second day. The pooled samples were centrifuged to remove solids, and the supernatant was sterilized by membrane filtration. The sterile fecal supernatants were then dialyzed for 48 h against two 15-liter changes of phosphate-buffered saline and subsequently tested for toxicity in cultured monolayers of mouse adrenal cells. A filterable toxin(s) was found in the fecal supernatants on days 2, 4, and 6 postchallenge and not in pretreatment samples. The toxin(s) caused enterocolitis when administered orogastrically to healthy animals and altered the morphology of cultured mouse adrenal cells. The alteration of adrenal cell morphology was neutralized by specific antitoxin to Clostridium histolyticum.

Adrenal Glands↗
PubMed1979

Synthetic peptide chemotactic factors for neutrophils: the range of active peptides, their efficacy and inhibitory activity, and susceptibility of the cellular response to enzymes and bacterial toxins.

The chemotactic activity for neutrophil leucocytes of twenty-six peptides of varied sequence, of which the majority were N-formylated, was assessed by determining the concentration at which each was maximally active and the efficacy of each peptide at that concentration. These two measures of activity did not correlate with one another. Many formylated peptides with a wide variety of sequences were active. Of these, the formyl-methionyl peptides had highest efficacy, but many other peptides were active at concentrations as low as the formyl-methionyl tripeptides. Unrelated peptides, viz formyl-methionyl-leucyl-phenylalanine, acetyl-tri-alanine, formyl-tri--phenyla-lanine, cross-inhibit the cells' response to one another, and this inhibition is reversible. Inhibition is prevented if the cells are incubated throughout the experiment in levamisole or A23187. These experiments suggest that the leucocyte peptide receptor is capable of binding many ligands, and that activation of a response is not solely a function of binding affinity. They exclude a strict steric specificity for binding. Chemotactic responses to formylated peptides were shown to be reduced in cells pretreated with perfringolysin, a bacterial cholesterol-binding toxin, and with phospholipase C. Trypsin and pronase also reduced these responses when used at 500 micrograms per 10(6) cells but not at lower doses.

Amino Acid Sequence↗
PubMed1978

[Bacterial toxins as cause of sudden infant death (author's transl)].

At post-mortems held on cot-death infants, the cause of death can be established as a variety of pathological changes. Inflammationin the region of the respiratory tract, in particular in the lungs;infections of the gastrointestinal tract; otitis media; shift of electrolytes-recently also the so-called yellow fat ect., can in association with the data on the anamnesis in many cases, through the assumption of bacterio-enterotoxin poisoning, which takes a different course in infants, to that in older children or adults, be traced back to a common origin. Extensive inquiries before the post-mortem, are as much indispensable prerequisites forthe clarification of the cause of sudden death as are the actual post-mortem and the ensuing investigations which must be carried out in the same way.

Bacterial Infections↗
PubMed1976

Pregnancy interrupting effects of some bacterial toxins.

Embryotoxic properties of Shigella dysenteriae and Clostridium perfringens toxins, of E. coli endotoxin, V. cholerase and E. coli enterotoxins were compared in mice. E. coli endotoxin has embryotoxic effects at all stages of pregnancy. E. coli enterotoxin V. cholerae enterotoxin and Shigella dysenteriae toxin are most effective mainly at earlier stages of pregnancy. Clostridium perfringens toxin has no embryotoxic effect.

Abortifacient Agents, Nonsteroidal↗
PubMed1976

Mechanism of the irreversible inhibition of aspartate aminotransferase by the bacterial toxin L-2-amino-4-methoxy-trans-3-butenoic acid.

The naturally occurring toxin L-2-amino-4-methoxy-trans-3-butenoic (AMB) acid irreversibly inhibits pyridoxal phosphate-linked aspartate aminotransferase. The inhibitor is a substrate for the enzyme, and as such is converted into a highly reactive intermediate which chemically reacts with an active site residue, thus irreversibly inactivating the enzyme. Enzymological and model studies on AMB are presented which enable one to determine the precise mechanism of action of this toxin. The mechanism involves Schiff base formation between the enzyme and toxin followed by alpha-C--H bond cleavage and aldimine isomerization to generate a bifunctional Michael acceptor. This molecule alkylates an active site residue by an addition and elimination route.

Aminobutyrates↗
PubMed1978

Ribonucleic acid in the immune response.

In the studies of experimental salmonellosis, immunization of mice with a live vaccine SER of S. enteritidis was found to be effective against further infection with virulent S. enteritidis 116--54. Macrophages obtained from the peritoneal cavity, subcutaneous tissue or liver of immunized mice inhibited intracellular growth of bacteria and resisted cell degeneration caused by engulfment of virulent 116--54 bacteria. This immunity was called cellular immunity. We discovered by chance in 1961 a transfer agent of immunity (TA) from the culture fluid of immunized macrophages. This agent is RNA in nature and can be extracted from the spleen, peritoneal exudate cells or the lymph node of immunized animals and is called immune (i) RNA. We could demonstrate antibody activity in macrophages treated in vitro or in vivo with iRNA by the immune adherence hemagglutination technique. Cellulr immunity against tumor cells could be transferred in vitro or in vivo to lymphocytes through iRNA prepared from the spleen cells of syngeneic, allogeneic and xenogeneic animals immunized with the tumor cells. We prepared iRNA against antigens capable of inducing humoral antibody production in animals, i.e., RBCs, bacterial toxin, bacterial flagella and hapten-protein conjugates. Serum antibody was not demonstrated in recipient animals of iRNA's by single or repeated injections of these agents. However, in these animals an increase in the number of specific antibody-carrying cells was found as rosette-formers. It was found further that prior injection of iRNA could induce immunologic memory and produced a high titer of humoral antibody after a boosting stimulation with a small dose of the corresponding antigen. The required interval between the first iRNA and the second antigenic stimulation, and the minimal effective doses of iRNA and antigen are described. We studied the interaction of iRNA with either T- or B-cells and with both cells using adoptive transfer system, athymic nude mice and neonatally thymectomized (NT) mice. Immune rna's against T-dependent and T-independent antigens could not induce the proliferation of antibody-carrying cells in cyclophosphamide-treated (B-cell depleted) mice. But these agents could induce the proliferation of rosette-formers, implying that iRNA's can replace some role of T-cells even against T dependent antigens. B-cells can be directly activated by treatment with iRNA against both T-dependent and T-independnet antigens, and they differentiated into rosette-formers. Passive transfers of iRNA were successful in establishing immunity against infection with S. enteritidis, or immunity to Salmonella flagella, RBCs and hapten-protein conjugates. The ability of iRNA to confer a secondary response of antibody formation is serially and passively transmissible in recipient animals. These facts suggest the presence of some mechanism that is responsible for the amplification of antigenic stimulation in the immune response...

Animals↗