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Biomedical subjects

K Zak

Publications and source records attributed to K Zak.

15 recordsLinked to original sources
PubMed1987

Immunobiology of gonococcal outer membrane protein I.

Monoclonal antibodies have been obtained which react with gonococcal outer membrane protein I. One antibody recognised the majority of strains expressing P.IA and another recognised the majority of strains expressing P.IB. In in vitro tests both antibodies were bactericidal in the presence of complement, opsonic for phagocytosis by human PMN and protected epithelial cells against gonococcal invasion. Thus conserved epitopes on P.I. are potentially effective targets for immunoprophylaxis.

Animals↗
PubMed1987

Outer membrane protein III of Neisseria gonorrhoeae: variations in biological properties of antibodies directed against different epitopes.

Monoclonal antibodies (mAbs) have been raised to gonococcal outer membranes. A panel of six mAbs was identified by several criteria as reacting with outer membrane protein III (P.III). Competitive radioimmunoassays showed that the mAbs could be grouped into three pairs recognizing different epitopes on P.III. These epitopes are equally present on all pathogenic Neisseria. The mAbs demonstrated differing protective effects in model systems. Those directed against one epitope were particularly effective in protecting Chang conjunctiva epithelial cells against gonococcal challenge. mAbs against this epitope and another promoted complement-mediated bactericidal activity, while those directed against the third epitope were ineffective. Thus the biological effects of mAbs directed against P.III vary according to the epitope recognized.

Antibodies, Monoclonal↗
PubMed1987

The potential protective effect of monoclonal antibodies to gonococcal outer membrane protein IA.

Hybrid cell lines were derived which produced monoclonal antibodies directed against gonococcal outer membrane protein IA. One antibody, SM101, recognized 24 P.IA-expressing strains out of 25 tested--the rest exhibited relatively less cross-reactivity. Competitive radioimmunoassays revealed that each antibody could effectively inhibit binding of the others, suggesting close proximity of the epitopes recognized. The antibodies were used in assays in vitro to investigate their potential efficacy in protection against gonococcal infection. In a cytotoxicity assay, the antibodies afforded some protection to epithelial cells challenged with gonococci. They were very effective at bactericidal killing in the presence of complement and, in addition, were opsonic for homologous and heterologous strains. The cross-reacting antibody, SM101, was one of the most effective in both assays. The results show that the conserved epitope on P.IA recognized by antibody SM101 is potentially an effective target on the gonococcal surface for immunoprophylaxis.

Antibodies, Monoclonal↗
PubMed1986

Monoclonal antibodies to gonococcal outer membrane protein I: location of a conserved epitope on protein IB.

Hybrid cell lines have been derived which produce monoclonal antibodies reacting with outer membrane protein I from Neisseria gonorrhoeae strain P9. The antibodies obtained showed variable reactivity with other strains but one antibody recognized an epitope present on all of the strains tested which expressed the protease sensitive protein IB. Purified IgG labelled with 125I was used in competitive radioimmunoassays with unlabelled antibody to investigate the spacial distribution of the epitopes recognized. Each pair of antibodies showed some degree of inhibition. The relative magnitude of inhibition suggested that the conserved epitope lies within a variable region containing other epitopes which determine the antigenic specificity of the protein. Western blotting of peptides derived by proteolytic digestion of protein IB revealed that the conserved epitope is located close to the chymotrypsin cleavage site within a 7000 Mr surface exposed region of the molecule.

Antibodies, Bacterial↗
PubMed1986

Monoclonal antibodies to gonococcal outer membrane protein IB: use in investigation of the potential protective effect of antibodies directed against conserved and type-specific epitopes.

Several monoclonal antibodies directed against gonococcal outer membrane protein IB have been used in in vitro assays to investigate their potential efficacy in protection against gonococcal infection. In a cytotoxicity assay, virulence of the variant P9-17 for epithelial cells in tissue culture was reduced in the presence of three of the four antibodies which recognized type-specific epitopes. Similarly, virulence of P9-17 as well as a recent isolate was reduced in the presence of the one antibody, SM24, which reacted with a conserved epitope. This antibody was also bactericidal in the presence of complement, and in addition was opsonic for several protein IB-expressing strains as determined by polymorphonuclear leucocyte chemiluminescence measurements. Similarly, all the type-specific antibodies were opsonic for P9 variants. However, only two of these antibodies mediated complement-dependent killing although those which were ineffective were nevertheless complement-fixing antibodies. These results indicate that antibodies to closely positioned epitopes on protein I vary in their biological activities and that the conserved epitope recognized by the antibody SM24 is potentially an effective target on the gonococcal surface for immunoprophylaxis.

Antibodies, Bacterial↗
PubMed1984

Antigenic variation during infection with Neisseria gonorrhoeae: detection of antibodies to surface proteins in sera of patients with gonorrhea.

Neisseria gonorrhoeae were cultured from the urethra of male patients and from the cervix and urethra of female contacts. Isolates from a given group of individuals were of the same strain but differed considerably in terms of the molecular weight of both protein II and pili. Radioimmunoprecipitation assays showed that most patients produced serum antibodies to protein I. Antibodies to pili, when present, showed limited cross-reactivity with the different pili produced by a single strain. Antibodies to protein II were highly specific, reacting with only one of the protein II-types produced by a single strain; this observation suggested that the host immune response may be an important factor in antigenic variation. Several sera also contained antibodies to a common surface protein with a molecular weight of 43,000 that was present in all strains tested.

Antibodies, Bacterial↗
PubMed1983

Structural variations in pili expressed during gonococcal infection.

Gonococci were cultured from the urethra of male patients and from the cervix and urethra of their female partners. SDS-PAGE of cell lysates from within each group of consorts showed that outer membrane protein I remained constant but considerable variations were seen in the apparent molecular weight of protein II. Pili were purified from the isolates of some groups of consorts. In each case the pili expressed by the isolates from the female cervix and urethra differed in subunit molecular weight and were usually also distinct from the pili expressed by the isolate from the male partner.

Bacterial Outer Membrane Proteins↗
PubMed1982

[Interdisciplinary experimental studies on the biomechanics of extensor and flexor tendon injuries of the hand].

The interdisciplinary experimental computer test for determination of the biomechanics of extensor and flexor tendon injuries at the distal phalanx of the fingers were performed with the aid of the finite element method. By input of the extreme boundary values (stress, biomechanic system, deformation and movement behavior, material coefficent distribution), it was possible to simulate clinically occurring injuries. Pathogenetically crucial for the type of injury are chance factors, which lead to a particular constellation of static or dynamic stress conditions. Accordingly, maximal stress exceeding the material coefficients occurs either in the region of the tendon or at the bone insertion. The finite element procedure reproduces the maximal main, normal and shearing stress at the site corresponding to the rupture and has proven to be a suitable method of simulation and analysis.

Biomechanical Phenomena↗