Biomedical subjects

H Hofstra

Publications and source records attributed to H Hofstra.

25 records · Page 2Linked to original sources

PubMed1982

Effect of beta-lactam antibiotics of the resistance of the digestive tract of mice to colonization.

Four broad-spectrum antibiotics-azlocillin, mezlocillin, cefuroxime, and moxalactam - were injected subcutaneously into mice twice a day. The animals divided into treatment groups for each antibiotic and then into subgroups, each subgroup receiving a different dose of antibiotic. The effect of treatment on the resistance of the digestive tract to colonization and the effect of treatment on endogenous gram-negative and intestinal streptococcal flora was studied: resistance to colonization decreased during treatment with approximately 0.9 mg of antibiotic per mouse per day. During treatment with this dose or a higher dose, Escherichia coli or a strain of Enterobacter resistant to the antibiotic being used grew to significantly higher numbers per gram of feces than in the control groups. The resistance of the digestive tract to colonization in mice decreases during systemic treatment with all four antibiotics at or above certain dose levels, a result also likely to occur in humans.

Animals↗

PubMed1981

Porin from the outer membrane of Escherichia coli: immunological characterization of native and heat-dissociated forms.

Antisera against porin oligomers isolated from the outer membrane of Escherichia coli O26K60 and against porin monomers from the same bacterial strain were elicited in rabbits by intramuscular administration with Freund's complete adjuvant. Antibodies against native porin oligomers reacted strongly with porin oligomers, as revealed by sodium dodecyl sulphate-polyacrylamide gel immunoperoxidase (SGIP) analysis, the enzyme-linked immunosorbent assay (ELISA) and immunodiffusion, but showed no significant reaction with denatured monomers. The antibodies were completely absorbed by the intact outer membrane-peptidoglycan complex, which suggests that they were directed against antigenic determinants expressed on the outside of the intact outer membrane. Antibodies directed against denatured porin monomers reacted strongly with monomers in all tests but reacted only very weakly with porin oligomers. They were not absorbed by the native porin situated in the intact outer membrane. This indicates that the major antigenic determinants of the denatured porin monomer are hardly related to those of the native trimer situated in the intact outer membrane. The antigenic determinants of the denatured monomer seem to become fully expressed only after dissociation and denaturation of the porin. It is concluded that the immunological relationship of denatured porin monomers derived from many strains of E. coli and other Enterobacteriaceae which was reported in previous studies may not indicate that native porin trimers of these strains are also related.

Antibodies, Bacterial↗

PubMed1980

Preparation and quantitative determination of antibodies against major outer mambranes proteins of Escherichia coli O26 K60.

Antisera against isolated outer membrane (OM) proteins I and II of Escherichia coli O26 K60 were elicited in rabbits. Antisera obtained after intramuscular administration with Freund's complete adjuvant showed high titres of specific antibodies. Intravenous administration of the same preparations yielded a considerable antibody response against bacterial lipopolysaccharide, a minor contaminant of the protein preparations. Antibody titres against OM proteins I and II, lipopolysaccharide and murein-lipoprotein were determined by the enzyme-linked immunosorbent assay (ELISA) in these sera, and in antisera elicited against whole formaldehyde-fixed bacteria or isolated OM. Comparison of ELISA with single radial immunodiffusion and interfacial immunoprecipitation tests revealed that ELISA was not only the most uniformly applicable, but also the most specific and the most convenient method. In double diffusion tests no cross-reactivity between proteins I and II was seen. Antibodies against proteins I and II, lipopolysaccharide and lipoprotein could be specifically absorbed from the sera with the appropriate antigen preparations. Absorption experiments with intact E. coli O26 K60, Tris/EDTA-sheared bacteria and isolated OM revealed that antibodies against protein I were hardly absorbed at all probably because the antibody, evoked against denatured protein I, did not react with the protein in its native configuration. Antibodies against protein II and lipoprotein were absorbed by intact as well as by sheared bacteria, but to a much greater extent by isolated OM, which indicates that these OM components are accessible from the outside, but that they are situated relatively deep in the OM structure.

Animals↗

PubMed1980

Major outer membrane proteins: common antigens in enterobacteriaceae species.

The major outer membrane (OM) proteins of 23 enterobacterial strains (principally clinical isolates) and five non-Enterobacteriaceae species were investigated by the sodium dodecyl sulphate-polyacrylamide gel immunoperoxidase (SGIP) technique to evaluate antigenic cross-reactivity among these proteins. All enterobacterial strains contained one or more peptidoglycan-associated major OM proteins, cross-reactive with the peptidoglycan-bound protein I of Escherichia coli, and one non-peptidoglycan-bound heat-modifiable protein, cross-reactive with protein II of E. coli. Results indicated that antigenic cross-reactivity of the major OM proteins is a general phenomenon in the family Enterobacteriaceae, independent of any molecular weight variation of the corresponding proteins in different bacterial strains. SGIP experiments carried out with OM preparations of other species showed no cross-reactivity of any of their OM proteins with enterobacterial major OM proteins. The significance of the immunological relatedness of OM proteins for the classification of some Enterobacteriaceae is discussed.

Antigens, Bacterial↗

PubMed1980

Cross-reactivity of major outer membrane proteins of Enterobacteriaceae, studied by crossed immunoelectrophoresis.

Outer membrane fractions were prepared from 11 bacteria in the family Enterobacteriaceae: Escherichia coli serotypes O1K-, O4K2, O26K60, O75K-, and O111K58, Shigella flexneri, Salmonella typhimurium, Klebsiella pneumonia, Serratia marcescens, Proteus vulgaris, Proteus mirabilis, and Providencia stuartii. All strains studied were found to contain one non-peptidoglycan-bound, heat-modifiable outer membrane protein, and one or two peptidoglycan-associated major outer membrane proteins in the 27,000- to 40,000-dalton range. Crossed immunoelectrophoresis using sodium dodecyl sulfate-polyacarylamide gel electrophoresis for separation of the antigens in the first dimension of the procedure was shown to provide a useful model system for studying the antigenic relationships of the major outer membrane proteins in Enterobacteriaceae species. Peptidoglycan-bound major outer membrane proteins of all bacteria studied reacted with antiserum against the purified peptidogylcan-bound matrix protein I of E. coli O26K60 in this system. Non-peptidoglycan-associated proteins of all strains cross-reacted with protein II of E. coli O26K60 in both their unmodified and their heat-modified forms. These results indicate that the genes coding for the major outer membrane proteins in the family Enterobacteriaceae have been well enough conserved during the course of evolution to allow significant antigenic cross-reactivity between the corresponding proteins in different enterobacterial species.

Antigens, Bacterial↗

PubMed1979

Antigenic cross-reactivity of major outer membrane proteins in enterobacteriaceae species.

The protein constituents in the outer membrane (OM) of several serotypes of Escherichia coli and some other Enterobacteriaceae cross-reacted antigenically. Solubilized OM preparations of these bacteria were applied in interfacial precipitin tests to antisera elicited in rabbits against whole bacterial cells, absorbed with their appropriate lipopolysaccharide before testing. The resulting immunecomplexes were analysed on polyacrylamide gels. Protein profiles of the immunoprecipitates showed a considerable antigenic cross-reactivity of outer membrane proteins between most E. coli serotypes. Cross-reactivity, though substantially lower, was also found with OM from three other Enterobacteriaceae species, but was not detectable with Pseudomonas aeruginosa OM. When OM preparations were solubilized at room temperature, the peptidoglycan-bound proteins in the molecular weight range 37,000 to 41,000 predominated in the protein profiles of the immunecomplexes. In profiles of immunecomplexes obtained with boiled OM preparations, a heat-modifiable protein (mol. wt 33,000) predominated. The major OM proteins of the Gram-negative bacterium may therefore play a role as common surface antigens of the family of Enterobacteriaceae.

Antigen-Antibody Complex↗

PubMed1978

Antibodies against outer membrane proteins in rabbit antisera prepared against Escherichia coli O26 K60.

Antibodies directed against the protein constituents of the outer envelope membrane of Escherichia coli O26 K60 were demonstrated in antisera elicited in rabbits against three different preparations of the bacterium. Outer membraned solubilized by sodium dodecyl sulphate were applied to the antisera in an interfacial precipitin test, followed by polyacrylamide gel electrophoretic analysis of the resulting immunecomplexes. Protein profiles showed a complete outer membrane protein pattern, indicating the antigenic character of these proteins. Antisera containing antibodies against outer membrane proteins and free of reactive antibodies against lipopolysaccharide showed relatively low agglutinating activities against the bacteria. The antibodies against the protein constituents of the outer membrane belong mainly to the 7S class immunoglobulins, as indicated by 2-mercaptoethanol treatment of the antisera.

Agglutination Tests↗