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Biomedical subjects

E J Hansen

Publications and source records attributed to E J Hansen.

139 records · Page 8Linked to original sources
PubMed1982

Antibody response of infants to cell surface-exposed outer membrane proteins of Haemophilus influenzae type b after systemic Haemophilus disease.

The immune response of nine infants with Haemophilus influenzae type b meningitis was examined by using a radioimmunoprecipitation procedure designed to detect antibodies directed against cell surface-exposed outer membrane proteins of this pathogen. Using intrinsically or extrinsically radiolabeled intact H. influenzae type b cells with acute- and convalescent-phase human sera in this radioimmunoprecipitation system, we found that all of the infants produced an antibody response directed against several different H. influenzae type b outer membrane proteins. Anti-H. influenzae type b outer membrane protein antibodies present in convalescent sera, but not found in acute sera, were directed against cell surface-exposed H. influenzae type b outer membrane proteins. In contrast, both acute and convalescent sera contained antibody activity directed against numerous H. influenzae type b outer membrane proteins whose antigenic determinants were apparently inaccessible to antibody on intact H. influenzae type b cells. The ability of infants to develop an antibody response to cell surface-exposed, antibody-accessible H. influenzae type b outer membrane proteins indicates that these proteins may have vaccinogenic potential.

Antibodies, Bacterial↗
PubMed1981

Characterization of hemadsorption-negative mutants of Mycoplasma pneumoniae.

Previously isolated mutants of Mycoplasma pneumoniae incapable of hemadsorption were characterized with respect to specific protein content, tracheal ring attachment capability, and virulence for both in vitro and in vivo model systems. Two-dimensional gel electrophoresis revealed both quantitative and qualitative differences between the protein complements of two different mutant strains and that of the virulent parent strain. Studies of mycoplasma attachment to hamster tracheal rings in vitro demonstrated that only one of these mutant strains still possessed the ability to attach to the respiratory epithelium via neuraminidase-sensitive receptors. Measurement of [3H]orotic acid uptake in mycoplasma-infected tracheal rings indicated that infection with the hemadsorption-negative mutants resulted in only slight reductions of ribonucleic acid synthesis, similar to levels observed for tracheal rings infected with an avirulent strain of M. pneumoniae. The virulence potential of the two mutant strains was further investigated by utilizing the hamster model system. Both mutant strains were rapidly cleared from the lungs of infected animals and produced little or no microscopic pneumonia.

Animals↗
PubMed1981

Identification of immunogenic outer membrane proteins of Haemophilus influenzae type b in the infant rat model system.

Outer membrane proteins of Haemophilus influenzae type b which are immunogenic in infant rats were identified by a radioimmunoprecipitation method. Intact cells of H. influenzae type b were radioiodinated by a lactoperoxidase-catalyzed procedure, and an outer membrane-containing fraction was prepared from these cells. These radioiodinated outer membranes were mixed with sera obtained from rats convalescing from systemic H. influenzae type b disease induced at 6 days of age, and the resultant (antibody-outer membrane protein antigen) complexes were extracted from these membranes by treatment with nonionic detergent and ethylenediaminetetraacetic acid. These soluble antibody-antigen complexes were isolated by means of adsorption to protein A-bearing staphylococci, and the radioiodinated protein antigens were identified by gel electrophoresis followed by autoradiography. Infant rats were shown to mount a readily detectable antibody response to several different proteins present in the outer membrane of H. influenzae type b. Individual infant rats were found to vary both qualitatively and quantitatively in their immune response to these immunogenic outer membrane proteins.

Animals↗
PubMed1981

Detection of antibody-accessible proteins on the cell surface of Haemophilus influenzae type b.

A radioimmunoprecipitation method has been devised which permits the direct identification of those proteins which are both exposed on the cell surface of Haemophilus influenzae type b and accessible to antibody. Both extrinsically and intrinsically radiolabeled cells of this organism were employed as the sources of antigen in radioimmunoprecipitation experiments which involved incubation of intact bacterial cells with antisera. Several different proteins, ranging in apparent molecular weight from 33,000 to 160,000, were shown to be accessible to antibody on the cell surface of this pathogen.

Antibodies, Bacterial↗
PubMed1979

Properties of mutants of Escherichia coli lacking malic dehydrogenase and their revertants.

Mutants of Escherichia coli lacking malic dehydrogenase activity (mdh) were incapable of growth on acetate", succinate- or malate/mineral medium. Revertants of mdh strains which had regained the ability to grow on C4-dicarboxylic acids could be divided into two distinct classes. One type of revertant had regained the ability to synthesize functional malic dehydrogenase. The other type of revertant still lacked malic dehydrogenase activity but possessed a suppressor mutation which altered the regulation of the synthesis or activity of the C4-dicarboxylic acid transport system, resulting in increased C4-dicarboxylic acid transport activity. This latter class of revertants apparently synthesized oxalacetate from malate via the sequential actions of the NAD-linked malic enzyme, phosphoenolpyruvate synthetase, and phosphoenolpyruvate carboxylase. Evidence has been presented that is consistent with the hypothesis that oxalacetate is the inducer of the C4-dicarboxylic acid transport system. The inability of mutants lacking malic dehydrogenase to grow with a C4-dicarboxylic acid as the carbon source can be attributed to the difficulty such mutants have in synthesizing oxalacetate.

Escherichia coli↗
PubMed1979

Two-dimensional gel electrophoretic comparison of proteins from virulent and avirulent strains of Mycoplasma pneumoniae.

The protein composition of the virulent M129 strain of Mycoplasma pneumoniae was compared to that of its homologous avirulent strain by the use of standard one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Forty-nine individual M. pneumoniae cell proteins were resolved by this method, and the virulent strain was shown to possess a single high-molecular-weight protein not present in avirulent cells. Variability in the resolution of this particular protein in one-dimensional gels prompted the application of two-dimensional gel electrophoresis to the analysis of M. pneumoniae cell proteins. The sequential use of isoelectric focusing in the first dimension and sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the second dimension permitted the resolution of a least 142 individual M. pneumoniae cell proteins. Application of nonequilibrium pH gradient electrophoresis in the first dimension achieved the resolution of at least 20 additional basic proteins. Three proteins which are synthesized only by cells of the virulent strain, and not by the homologous avirulent strain, were identified by these two-dimensional gel electrophoresis techniques.

Bacterial Proteins↗
PubMedDate not supplied

Haemophilus influenzae type b disease after rifampin prophylaxis in a day care center: possible reasons for its failure.

Five infants enrolled in a day care center (DCC) developed invasive disease due to Haemophilus influenzae type b during a 25-week period. The isolates from four patients had identical outer membrane proteins and were biotype 1. Although rifampin prophylaxis was recommended on two different occasions, retrospective surveys demonstrated that 39 and 60%, respectively, of infants failed to receive the agent for various reasons. Pharyngeal cultures were obtained from infants, their families and DCC staff after prophylaxis was given the second time. Forty-seven % of DCC infants had positive cultures, and 59% of their households had at least one carrier of the invasive strain. Rifampin prophylaxis administered a third time to infants and members of their households was unsuccessful in eradicating the invasive Haemophilus influenzae type b strain from DCC infants. The possible reasons for failure of rifampin in this DCC outbreak included incomplete understanding by physicians and health department officials of the factors affecting a DCC outbreak of Haemophilus influenzae type b disease and failure properly to implement rifampin prophylaxis to all contacts and the index cases.

Child Day Care Centers↗