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Biomedical subjects

J B Baseman

Publications and source records attributed to J B Baseman.

At least 73 records · Page 4Linked to original sources
PubMed1985

Fibronectin tetrapeptide is target for syphilis spirochete cytadherence.

The syphilis bacterium, Treponema pallidum, parasitizes host cells through recognition of fibronectin (Fn) on cell surfaces. The active site of the Fn molecule has been identified as a four-amino acid sequence, arg-gly-asp-ser (RGDS), located on each monomer of the cell-binding domain. The synthetic heptapeptide gly-arg-gly-asp-ser-pro-cys (GRGDSPC), with the active site sequence RGDS, specifically competed with 125I-labeled cell-binding domain acquisition by T. pallidum. Additionally, the same heptapeptide with the RGDS sequence diminished treponemal attachment to HEp-2 and HT1080 cell monolayers. Related heptapeptides altered in one key amino acid within the RGDS sequence failed to inhibit Fn cell-binding domain acquisition or parasitism of host cells by T. pallidum. The data support the view that T. pallidum cytadherence of host cells is through recognition of the RGDS sequence also important for eukaryotic cell-Fn binding.

Binding, Competitive↗
PubMed1985

Fibronectin mediates Treponema pallidum cytadherence through recognition of fibronectin cell-binding domain.

The specificity of the interaction between Treponema pallidum and fibronectin was demonstrated. Treatment of host cells with only antifibronectin sera and not anticollagen or antilaminin sera, inhibited treponemal cytadsorption. Incubation of fibronectin-coated coverslips with monoclonal antibody to the cell-binding domain of fibronectin reduced treponemal attachment to the same extent as antifibronectin serum. Both iodinated fibronectin and iodinated cell-binding domain bound to T. pallidum in a saturable manner. Specificity of the T. pallidum association with the cell-binding domain was the most effective inhibitor of the binding of either radioiodinated cell-binding domain or fibronectin to T. pallidum. Scatchard analysis gave Kd on the order of 10(-7) M for both cell-binding domain and fibronectin binding to T. pallidum, consistent with the high affinity interaction of these organisms with host cell surfaces. Finally, the same level of attachment of treponemes was achieved on coverslips coated with cell-binding domain as that observed for organisms incubated with fibronectin, indicating that the cell-binding domain polypeptide is functionally identical to fibronectin in mediating T. pallidum adherence.

Adhesiveness↗
PubMed1985

Detection of Mycoplasma pneumoniae adhesin (P1) in the nonhemadsorbing population of virulent Mycoplasma pneumoniae.

Mycoplasma pneumoniae organisms possessing a hemadsorbing-negative (HA-) phenotype comprise more than 50% of the population of virulent M. pneumoniae cultures. Monoclonal antibody to P1, the major adhesin of M. pneumoniae reacts with this HA- mycoplasma fraction based upon radioimmunoprecipitation and immunoblotting. Demonstration of P1 in the entire mycoplasma population suggests that topological organization of this adhesin in the membrane or the physiological state of the mycoplasmas may determine hemadsorbing capabilities.

Adhesins, Bacterial↗
PubMed1985

Putative Treponema pallidum cytadhesins share a common functional domain.

Three putative Treponema pallidum ligands (P1, P2, and P3) that bind host fibronectin were characterized by peptide mapping. Papain digestion of each protein yielded a comigrating peptide of approximately 12,000 molecular weight. An antibody to this protein fragment inhibited T. pallidum host cytadherence, indicating that this peptide may be the functional domain of these treponemal adhesins.

Adhesiveness↗
PubMed1985

Detection of the major adhesin P1 in triton shells of virulent Mycoplasma pneumoniae.

Filamentous structures designated Triton shells were obtained from virulent Mycoplasma pneumoniae by treatment with Triton X-100. Monoclonal antibodies directed against M. pneumoniae were used in conjunction with radioimmunoprecipitation and Western blotting to detect immunologically reactive polypeptides in Triton shells. The major adhesin, protein P1, was associated with these structures.

Adhesins, Bacterial↗
PubMed1985

Growth requirements of ferret tracheal epithelial cells in primary culture.

In mass cell culture conditions, protease dissociated ferret tracheal epithelial cells (FTE) proliferated in growth factor-supplemented F12 medium to high cell densities (0.5 X 10(5) cells/cm2) with an average population doubling time of 24 hr. The growth factor constituents of the F12 medium included epidermal growth factor (25 ng/ml), insulin (1 microgram/ml), transferrin (10 micrograms/ml), hydrocortisone (18 ng/ml), hypothalamus extract (30-100 micrograms/ml), and conditioned medium from mouse 3T3 fibroblasts. Growth of these cells under clonal conditions was achieved by the partial replacement of F12 medium with M199 medium which was attributed, in part, to the presence of vitamin A in M199 medium. Serum did not stimulate the growth of FTE cells. The epithelial cell nature of these cells in culture was confirmed by ultrastructural features and by immunofluorescent staining for fibronectin.

Animals↗
PubMed1984

Absence of Mycoplasma pneumoniae cytadsorption protein P1 in Mycoplasma genitalium and Mycoplasma gallisepticum.

Polyclonal and monoclonal antibodies to Mycoplasma pneumoniae protein P1 were nonreactive with whole-cell or soluble preparations of M. genitalium and M. gallisepticum. However, radioimmunoprecipitation performed with hyperimmune rabbit sera raised against each mycoplasma species indicated antigenic cross-reactivity between M. pneumoniae and M. genitalium.

Adhesins, Bacterial↗
PubMed1984

Distinctions among pathogenic human mycoplasmas.

Cytadsorption by Mycoplasma pneumoniae requires dense clustering of the surface membrane protein, P1, at the extreme end of the mycoplasma tip-like organelle. M. pneumoniae mutants incapable of cytadsorption either lack P1 or cannot mobilize and cluster P1 at the terminus. Specific cytadsorption-associated proteins in addition to P1 have been shown by mutant and revertant analysis to be essential for cytadsorption. Using monoclonal antibody probes and surface iodination techniques, additional chemical differences were observed between wild-type and mutant M. pneumoniae. M. genitalium, the recently identified new species, possesses structural and antigenic properties that appear similar to M. pneumoniae. Studies were initiated to establish the relatedness between M. pneumoniae and M. genitalium in terms of cytadsorption and membrane proteins.

Bacterial Proteins↗
PubMed1983

An ELISA to detect monoclonal antibodies specific for lipid determinants of Mycoplasma pneumoniae.

An enzyme-linked immunosorbent assay (ELISA) was developed for analysis of monoclonal antibodies directed towards lipid determinants of Mycoplasma pneumoniae. Chloroform-methanol lipid extracts as well as chromatographed lipid fractions of M. pneumoniae were bound to polyvinylchloride microtiter wells. Of 293 clones positive to M. pneumoniae as detected by a whole cell ELISA, a total of 78 clones produced antibodies which selectively bound to lipid extracts of M. pneumoniae. The simplicity and reproducibility of the assay permit rapid screening for detection of antibodies directed against non-protein cellular antigens.

Animals↗
PubMed1983

Treponema pallidum receptor binding proteins interact with fibronectin.

Analysis of plasma proteins avidly bound to T. pallidum surfaces revealed the ability of T. pallidum to acquire numerous host macromolecules. No acquisition was evident by the avirulent spirochete, T. phagedenis biotype Reiter. Western blotting technology using hyperimmune antifibronectin serum as a probe revealed the ability of virulent treponemes to avidly bind fibronectin from a complex medium such as plasma. The specificity of the tiplike adherence of motile T. pallidum to fibronectin-coated glass surfaces and to fibronectin on HEp-2 cells was reinforced by the observation that pretreatment of coverslips or cell monolayers with monospecific antiserum against fibronectin substantially reduced T. pallidum attachment. The stoichiometric binding of T. pallidum to fibronectin-coated coverslips and the inability of unlabeled or 35S-radiolabeled treponemes to interact with glass surfaces treated with other plasma proteins further established the specific nature of the interaction between virulent T. pallidum and fibronectin. The avid association between three outer envelope proteins of T. pallidum and fibronectin was also demonstrated. These treponemal surface proteins have been previously identified as putative receptor-binding proteins responsible for T. pallidum parasitism of host cells. The data suggest that surface fibronectin mediates tip-oriented attachment of T. pallidum to host cells via a receptor-ligand mechanism of recognition.

Bacterial Proteins↗
PubMed1983

Host discrimination of Mycoplasma pneumoniae proteinaceous immunogens.

The immune response of experimentally infected hamsters and human patients to Mycoplasma pneumoniae was examined by radioimmunoprecipation in conjunction with gel electrophoresis and fluorography. Both intrinsically and extrinsically labeled mycoplasma proteins were coincubated with acute and convalescent sera in a radioimmunoprecipitation assay. Two M. pneumoniae proteins were selectively precipitated by convalescent sera. These predominant immunogens were trypsin-sensitive, antibody-accessible surface proteins that co-migrate on polyacrylamide gels with proteins P1 and P2, which were previously implicated by us as mediators of cytadsorption. Anti-M. pneumoniae antiserum did not precipitate radiolabeled antigens derived from Mycoplasma orale or Mycoplasma salivarium. These data indicate that M. pneumoniae infection stimulates a specific and highly targeted host antibody response to key proteinaceous immunogens.

Acute Disease↗
PubMed1983

Reacquisition of specific proteins confers virulence in Mycoplasma pneumoniae.

Hemadsorbing revertants were isolated from spontaneous hemadsorption-negative, avirulent mutants of Mycoplasma pneumoniae. The revertants simultaneously reacquired specific proteins absent in their homologous mutants, along with neuraminidase-sensitive adherence to the respiratory epithelium and virulence. Peptide mapping and immunological analysis indicated no precursor-product relationships among certain of these proteins.

Adhesiveness↗
PubMed1983

Hemadsorption and virulence are separable properties of Mycoplasma pneumoniae.

A selective enrichment technique was used to isolate a hemadsorption-positive revertant of a hemadsorption-negative mutant strain of Mycoplasma pneumoniae. This hemadsorption-positive revertant was shown to have simultaneously regained both the ability to attach to neuraminidase-sensitive receptors on the tracheal ring respiratory epithelium in vitro and the ability to synthesize three virulent-strain-specific proteins which were not synthesized by the hemadsorption-negative mutant. Despite the persistence of the revertant in hamster lung tissue for 9 to 12 weeks postinfection, no cytopathology was observed. Intranasal inoculation of the revertant provided limited protection against a challenge dose of virulent M. pneumoniae.

Adhesiveness↗
PubMed1983

Inhibition of mycoplasma pneumoniae hemadsorption and adherence to respiratory epithelium by antibodies to a membrane protein.

Antiserum and purified immunoglobulin directed against Mycoplasma pneumoniae membrane protein P1 were examined for their influence on mycoplasma viability, metabolism, and cytadsorption. Anti-P1 immunoglobulin inhibited adherence of M. pneumoniae to hamster tracheal rings in vitro by up to 80% and inhibited hemadsorption by greater than 90%. Cytadsorption was also inhibited by anti-P1 Fab fragments. Anti-P1 antibodies had no effect on M. pneumoniae viability or metabolism. The data indicate that anti-P1 antibody obstructs the interaction of M. pneumoniae adhesin P1 with its host receptors.

Adhesins, Bacterial↗
PubMed1983

Comparison of major protein antigens and protein profiles of Treponema pallidum and Treponema pertenue.

The protein profiles of Treponema pallidum and Treponema pertenue, the causative agents of syphilis and yaws, respectively, were compared by one- and two-dimensional gel electrophoresis. One-dimensional gels showed essentially no differences in the protein patterns of these treponemes. On two-dimensional gels most radiolabeled protein species were shared; however, variations were noticed in several minor protein species. Antigenic comparison by radioimmunoprecipitation and Western blotting also demonstrated similarities between these spirochetes. However, lactoperoxidase-catalyzed iodination of T. pallidum and T. pertenue suggested differences in their surface proteins.

Animals↗
PubMed1983

Enzyme-linked immunosorbent assay for the detection of serum antibody to outer membrane proteins of Treponema pallidum.

A highly sensitive enzyme-linked immunosorbent assay was used for the analysis of serum IgG reactivity against specific immunogenic Treponema pallidum proteins. Outer membrane treponemal proteins purified by preparative SDS-polyacrylamide gel electrophoresis were used as antigenic probes at concentrations as low as 100 ng per ml (5 ng per well in microtitre plates). Detection of anti-treponemal antibody was possible using rabbit syphilitic sera diluted to 1/10 000. The sensitivity of the assay was equal to or greater than that detected by radioimmuno-precipitation combined with gel electrophoresis and fluorography techniques and was capable of monitoring host IgG responses throughout the progress of the disease.

Animals↗