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Biomedical subjects

R S Stephens

Publications and source records attributed to R S Stephens.

88 records · Page 5Linked to original sources
PubMed1985

Molecular cloning and expression of Chlamydia trachomatis major outer membrane protein antigens in Escherichia coli.

DNA obtained from Chlamydia trachomatis (serovar L2) was partially digested with DNase I and inserted into the beta-galactosidase gene of bacteriophage lambda gt11. Seven recombinants were selected that produced immunoreactive fusion proteins which were detected with anti-C. trachomatis rabbit serum. One recombinant, designated lambda gt11/L2/33, reacted with various monoclonal antibodies that recognize species-, subspecies-, and type-specific determinants on the chlamydial major outer membrane protein (MOMP). Immunoblot analysis of a lambda gt11/L2/33 lysogen revealed a fusion protein that expressed a approximately 15,000-dalton carboxyl-terminal peptide of the chlamydial MOMP. This moiety of the MOMP possesses epitopes responsible for each of the unique reactivities demonstrated by anti-MOMP monoclonal antibodies. The lambda gt11/L2/33 recombinant contained a 1.1-kilobase DNA insert which hybridized to DNA isolated from each of the 15 C. trachomatis serovars.

Antibodies, Monoclonal↗
PubMed1984

Specific and common antigens of Trichomonas vaginalis detected by monoclonal antibodies.

Monoclonal antibodies to Trichomonas vaginalis were prepared by immunizing mice with a cloned isolate of T. vaginalis. Eight antibodies reacted with the same four isolates or strains but did not react with the other T. vaginalis strains or isolates tested. All eight antibodies reacted uniformly with both the body and flagella of T. vaginalis in the immunofluorescence assay but were unreactive by immunoblotting. The antigen(s) recognized by these antibodies was determined to be present on the surface membrane by indirect immunofluorescence assay of live organisms. The antigen(s) was found to be sensitive to periodate oxidation but resistant to pronase digestion. In addition, one monoclonal antibody was derived which reacted with all T. vaginalis isolates or strains tested, as well as with Trichomonas gallinae, Tritrichomonas foetus, and Giardia lamblia. This antibody reacted with the body but not the flagella of Formalin-fixed protozoa in the immunofluorescence assay but failed to react with live organisms. The antigen was found to be periodate resistant but pronase labile. In the immunoblot assay, this antibody detected a single T. vaginalis polypeptide with a molecular weight of 62,000.

Animals↗
PubMed1984

Chlamydia trachomatis species-specific epitope detected on mouse biovar outer membrane protein.

A common antigenic determinant on the chlamydial major outer membrane protein was detected on each of the three Chlamydia trachomatis biovars (trachoma, lymphogranuloma venereum, and mouse). This determinant was prominently displayed on the surface of chlamydial strains from both the trachoma and lymphogranuloma venereum biovars. However, detection of this determinant on a mouse biovar strain required denaturation by sodium dodecyl sulfate or periodate oxidation. This determinant provides a definable taxonomic link between the three biovars of C. trachomatis.

Animals↗
PubMed1984

Tubulin and high-molecular-weight polypeptides as Giardia lamblia antigens.

We determined the antigenic specificities of nine murine monoclonal antibodies to Giardia lamblia. Four distinct antibody reaction patterns were detected by immunofluorescence with G. lamblia trophozoites. Four monoclonal antibodies which reacted with the body but not the flagella of the whole trophozoites recognized two polypeptides of 170,000 and 155,000 molecular weights by immunoblotting. Two antibodies reacting with both the flagella and body also reacted with 170,000- and 155,000-molecular-weight antigens. An antibody specific for the G. lamblia attachment disk and two specific for flagella by immunofluorescence were found to react with 53,000- and 55,000-molecular-weight polypeptides by immunoblotting. These antigens comigrated with purified bovine brain tubulin, and their respective antibodies reacted in immunoblots with purified bovine brain tubulin. The antigens identified in this report were found to be present in Giardia cytoskeletal preparations. All antigens were pronase labile and heat stable. Four strains of G. lamblia reacted similarly in immunofluorescence assays as well as in immunoblotting assays.

Animals↗
PubMed1984

Direct fluorescent monoclonal antibody stain for rapid detection of infant Chlamydia trachomatis infections.

A method of direct fluorescent antibody staining for rapid diagnosis of Chlamydia trachomatis infections in infants is described. This method utilized a fluorescein-conjugated species-specific monoclonal antibody to C trachomatis for detecting chlamydial elementary bodies in smears of the conjunctiva, nasopharynx, oropharynx, anus, and vagina. The sensitivity of direct fluorescent antibody staining was compared with isolation of the organisms in McCoy cells. Thirty-nine infants with purulent conjunctivitis were studied. Diagnosis of C trachomatis conjunctivitis was correctly made by smear in all 16 infants when inflamed eyes were sampled. Positive smears were obtained from 12/14 culture-positive and 4/16 culture-negative nasopharyngeal specimens from infants with chlamydial conjunctivitis. All nasopharyngeal cultures and smears from infants with nonchlamydial conjunctivitis were negative. These results indicate that the direct smear test is a sensitive and specific test for diagnosing C trachomatis infection of the eye and nasopharynx in infants, and this test can be completed within one hour of specimen collection.

Antibodies, Monoclonal↗
PubMed1982

Effects of corticosteroids and cyclophosphamide on a mouse model of Chlamydia trachomatis pneumonitis.

Suppression of the inflammatory reaction with daily doses of cortisone acetate or cyclophosphamide substantially prolonged the pulmonary infection in mice which had been intranasally inoculated with a trachoma biotype of Chlamydia trachomatis. Titration of organisms recovered from the lungs of treated mice revealed a drop in titer after day 2 (postinfection), followed by a prominent increase on day 6. In cyclophosphamide-treated mice the infection was resolved after day 12, whereas in cortisone acetate-treated mice a significant titer remained after day 17. In contrast, no organisms were recoverable after day 6 in control mice treated with saline or in mice treated with hydrocortisone succinate. Histologically, the ability of cortisone acetate and cyclophosphamide to inhibit the inflammatory reaction correlated with the respective course of chlamydial pneumonitis. This study demonstrated that mice were intrinsically capable of sustaining a lung infection induced by a human strain of S. trachomatis.

Animals↗
PubMed1982

Sensitivity of immunofluorescence with monoclonal antibodies for detection of Chlamydia trachomatis inclusions in cell culture.

Monoclonal antibodies which recognize the species-specific major outer membrane protein antigen of Chlamydia trachomatis were used for immunofluorescence staining of chlamydial inclusions in cell culture. A total of 115 clinical specimens were inoculated onto replicate HeLa 229 cell monolayers and assayed for chlamydial inclusions by immunofluorescence staining and Giemsa staining. Of the isolates, 38 were detected by immunofluorescence staining on passage 1 and 1 was detected on passage 2; 23 isolates on passage 1 and 13 isolates on passage 2 were detected by Giemsa staining. Immunofluorescence staining was significantly more sensitive than Giemsa staining for detecting chlamydial inclusions, particularly from specimens containing low titers of Chlamydia.

Antibodies, Monoclonal↗
PubMed1982

Monoclonal antibodies to Chlamydia trachomatis: antibody specificities and antigen characterization.

Nineteen independent hybrid cell lines that produce monoclonal antibodies to Chlamydia trachomatis surface antigens were prepared by the fusion of mouse myeloma cells with lymphocytes of mice that were immunized with C. trachomatis immunotypes B, C, and L2. Seven serologically distinct reaction patterns were detected by microimmunofluorescence (micro-IF) of elementary body (EB) preparations when culture fluids were tested against a panel of 18 chlamydial serotyping reference strains. These reaction patterns demonstrated genus-, species-, subspecies-, and type-specific distributions. Additionally, these antibodies were tested in parallel against reticulate body (RB) preparations of several chlamydial strains. Monoclonal antibodies that reacted with genus-specific antigens reacted preferentially with RB, whereas antibodies that reacted to species-, subspecies-, or type-specific antigens reacted equivalently to both RB and EB. Physiochemical characterization of antigens recognized by the different monoclonal antibodies was assessed by heat treatment, pronase digestion, periodate oxidation, and immuno-blot techniques. The genus-specific antigen was a heat-stable, pronase-resistant, and relatively periodate-sensitive component of less than 10,000 m.w. The species-, subspecies-, and type-specific antigens were heat stable, pronase sensitive, and periodate resistant. The antibodies that detected species- and subspecies-specific antigens predominantly reacted in immuno-blots with the 40,000 m.w. major outer membrane protein. These monoclonal antibodies now provide a new approach for the precise serologic classification and detection of different C. trachomatis strains.

Animals↗
PubMed1976

Application of halide ion nuclear magnetic resonance to bioinorganic problems.

The basis for the application of halide ion nuclear magnetic resonance to the investigation of biochemical problems is reviewed and a summary of applications is presented. Anion binding to macromolecules, low molecular weight or model compounds, metalloenzymes, and extrinsic metal interactions with macromolecules are discussed.

Binding Sites↗
PubMedDate not supplied

Predictors of attrition from an outpatient marijuana-dependence counseling program.

We sought to characterize attrition-related characteristics of three subgroups of adults (i.e. early dropouts, late dropouts, treatment completers) who had participated in a marijuana-dependence treatment outcome study involving two alternative forms of outpatient group counseling. Early dropouts were younger, earned less income, were more likely to rent rather than own their domiciles, were less able to pay bills, and had a higher level of psychological distress than was the case with treatment completers. Late dropouts and completers were quite similar on a number of measures (e.g., age, income, home ownership, ability to pay bills, psychological stress level, confidence in being abstinent in the future), yet the lower rates of abstinence in the late dropouts largely resembled the treatment outcomes of early dropouts. The findings suggest that attrition prevention in the early phase of counseling ought to focus on motivational ambivalence as well as assisting the client in dealing with schedule conflicts or financial impediments to continued involvement. In the later stage of counseling, attrition reduction is more likely to be accomplished through efforts to better understand and address the client's dissatisfaction with treatment components delivered at that stage.

Adolescent↗
PubMedDate not supplied

Testing the abstinence violation effect construct with marijuana cessation.

It has been proposed that internal, stable, and global attributions for the cause of a lapse following a period of abstinence and concomitant feelings of guilt and loss of control increased the probability of a return to regular substance use. The Abstinence Violation Effect (AVE) hypotheses were tested in a sample of 75 adult marijuana users who reported a lapse into marijuana use following completion of either a relapse prevention (RP) or social support group treatment aimed at abstinence. Results showed that more internal, stable, and global attributions for the cause of the lapse and perceived loss of control were related significantly to concurrently reported relapse. Further, internal and global attributions predicted marijuana use during the subsequent 6 months. Results are discussed in terms of support for the AVE construct, treatment implications, and the failure of the RP treatment to modify reactions to a lapse.

Adult↗