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At least 721 records · Page 40Linked to original sources

PubMed1994

Safety, immunogenicity and an open, retrospective study of efficacy of a monocomponent pertussis toxoid vaccine in infants.

One hundred forty-five infants were vaccinated with 25 micrograms of pertussis toxoid (NICHD-Ptxd) at 3, 5 and 7 or at 3, 5 and 12 months of age. One month after the third vaccination all had high serum IgG and neutralizing antibodies (antitoxin) against pertussis toxin. Vaccination at 3, 5 and 12 months resulted in higher antibody titers than vaccination at 3, 5 and 7 months. Sera obtained from 109 children at 3 years of age showed a decline of antibodies, but all had detectable antibodies. Adverse reactions were confined to local redness and swelling, which exceeded 2 cm after 17% of all injections. When the children were 3 years old, a comparison was made of the incidence of clinical pertussis in 142 of the 145 vaccinated children and in 284 age-matched controls living in the same areas. Information on symptoms of pertussis was obtained from the parents during telephone interviews. None of the vaccinated children had clinical pertussis, defined as a 6-week course of paroxysmal cough with whooping attacks or vomiting, whereas 57 controls (20%) had experienced these symptoms. Sixteen vaccinated children were exposed to pertussis in the household. Two of them had laboratory-verified Bordetella pertussis infections with cough of 2 and 4 weeks, respectively, without whooping attacks or vomiting, whereas 14 did not develop a cough. The study shows that NICHD-Ptxd is immunogenic in infants and that it most likely confers a high degree of protection against pertussis.

Antibodies, Bacterial↗

PubMed1986

Early events in the action of staphylococcal alpha-toxin on the plasma membrane of adrenocortical Y1 tumor cells.

The early events in staphylococcal alpha-toxin action on mouse adrenocortical (Y1) tumor cells were studied. Cell-bound toxin could be partially neutralized by anti-alpha-toxin and inactivated by trypsin added within 10 min at 37 degrees C after the end of the binding step. Likewise, cell-bound toxin was capable of lysing rabbit erythrocytes (RRBC) added to the cells within 10 min after binding at 37 degrees C. After this time, the Y1 cells could not be rescued from intoxication by antibodies or trypsin, and the toxin was not accessible for lysis of RRBC. However, at 0 to 4 degrees C, the cell-bound toxin remained accessible to antibodies for at least 4 h. CaCl2 (30 mM) did not affect binding of the toxin to Y1 cells but completely prevented the intoxication if added within 10 min at 37 degrees C after the end of the binding step. The intoxication was independent of metabolic energy, active receptor clustering on the cell surface, and endocytosis of the toxin. Therefore, alpha-toxin interacted with the Y1 cell membrane in at least three separable steps: binding, a conformational change at the cell surface, and membrane damage. These early events appear to be similar to those occurring on RRBC treated with alpha-toxin.

Adrenal Cortex Neoplasms↗

PubMed1996

Purification and characterization of an extracellular secretogenic non-membrane-damaging cytotoxin produced by clinical strains of Vibrio cholerae non-O1.

Some clinical strains of Vibrio cholerae non-O1 produce an extracellular factor that evokes a rapid and dramatic cytotoxic response which manifests as cell rounding of Chinese hamster ovary (CHO) and HeLa cells without accompanying membrane damage. This study was performed to establish the identity of the non-membrane-damaging cytotoxin (NMDCY), which was not inhibited by antitoxins against cholera toxin, heat-labile toxin of enterotoxigenic Escherichia coli, El Tor hemolysin, Shiga-like toxin I, and Shiga-like toxin II, indicating that NMDCY did not bear an apparent immunological relationship with the above toxins and hemolysin. Brain heart infusion broth and AKI medium supported the maximal production of NMDCY; culture supernatant of AKI medium was found to be free of hemolysin activity, whereas in brain heart infusion broth hemolysin was coproduced with NMDCY. Maximal production of NMDCY in AKI medium was observed at 37 degrees C under shaking conditions with the pH of the medium adjusted to 8.5. NMDCY was purified to homogeneity by a three-step purification procedure which increased the specific activity of the cytotoxin by 1.7 X 10(5)-fold. The denatured molecular weight of the purified toxin was 35,000, and the cytotoxin was heat labile and sensitive to trypsin. Purification of the cytotoxin revealed an enterotoxic activity as reflected by its ability to accumulate fluid in the rabbit ileal loop. Both the cytotoxic and enterotoxic activities of NMDCY could be inhibited or neutralized by antiserum raised against purified cytotoxin but not by preimmune serum. Immunodiffusion test between purified NMDCY and antiserum gave a single well-defined precipitin band which showed reactions of complete identity, while, in an immunoblot assay, a well-defined single band was observed in the 35-kDa region. Our results indicate that the cytotoxic and enterotoxic activities expressed by NMDCY appear to contribute to the pathogenesis of the disease associated with V. cholerae non-O1 strains which produce this cytotoxin.

Animals↗

PubMed1965