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Biomedical subjects

S A Larsen

Publications and source records attributed to S A Larsen.

10 recordsLinked to original sources
PubMed1992

Specific immunofluorescent staining of pathogenic treponemes with a monoclonal antibody.

Two hybrid cell lines which produced mouse monoclonal antibody to the DAL-1 street strain of Treponema pallidum subsp. pallidum were established. These monoclonal antibodies strongly reacted with T. pallidum subsp. pallidum (Nichols strain, DAL-1, and two other street strains, strains MN-1 and MN-3) and T. pallidum subsp. pertenue by indirect microimmunofluorescent antibody and enzyme-linked immunosorbent assay techniques, but they did not react with normal rabbit testicular tissue. These monoclonal antibodies did not react with nonpathogenic treponemes, such as T. phagedenis Reiter, T. denticola MRB, T. refringens Noguchi, or other spirochetes, such as Borrelia burgdorferi and Leptospira interrogans serovar pomona in microimmunofluorescent antibody smear slides or in Western blots (immunoblots). While unlabeled antibodies are useful for investigating the antigenic structures of T. pallidum, we labeled these monoclonal antibodies with fluorescein isothiocyanate and used them for diagnosing syphilis by direct staining of lesion exudate or T. pallidum subsp. pallidum in formalin-fixed tissues from patients suspected of having syphilis. Both monoclonal antibodies were directed against antigens of T. pallidum subsp. pallidum with a molecular weight of 37,000 as determined by the Western blotting technique.

Animals↗
PubMed1979

Problems affecting performance of the fluorescent treponemal antibody-absorption test for syphilis.

Immunofluorescent staining of Treponema pallidum was studied to clarify the effect of three factors on the results of the fluorescent treponemal antibody-absorption test: (i) heat inactivation of sera at 56 degrees C for 30 min before testing, (ii) use of multicircle slides, and (iii) tungsten illumination to visualize and assess unstained treponemes on reactive as well as nonreactive smears. It was found that serum inactivation before testing was not necessary for detection of immunoglobin G antibody, but an immunoglobulin M prozone was detected in unheated serum. On multicircle slides, it was demonstrated that a false-positive reaction could be obtained in 30 s at 37 and 25 degrees C if a smear where a nonreactive serum had been placed was crossed by a strongly reactive serum from another circle. Tungsten illumination proved necessary for correct assessment of unstained treponemes on all fluorescent treponemal antibody-aborption test smears, reactive or nonreactive. The possible role of these factors in incorrect fluorescent treponemal antibody-absorption test results is discussed.

Antibodies, Bacterial↗
PubMed1978

Hemagglutination tests for syphilis antibody.

In a study of serodiagnosis of syphilis, the authors compared the specificities and sensitivities of two hemagglutination tests, a sheep-erythrocyte test (MHA-TP) and a trukey-erythrocyte test (TPHA), with those of the Fluorescent Treponemal Antibody-Absorption (FTA-ABS) test. In tests of sera from 935 patients without syphilis, the MHA-TP, TPHA, and FTA-ABS tests were reactive for 0.96, 0, and 1.3% respectively. The false-positive results were usually transient and not associated with underlying illness. For the 68 patients with syphilis, the MHA-TP test was as sensitive as the FTA-ABS test in all stages except untreated primary disease. The TPHA test appeared to be undersensitive, and testing of follow-up sera from persons with latent syphilis showed unexplained conversion of false-negative TPHA results to reactive results. Reproducibilities of the two hemagglutination tests were comparable. The MHA-TP test is a valuable confirmatory test for syphilis. Further study is needed before the use of the TPHA test can be recommended.

Animals↗
PubMed1978

Tests for treponemal antibody in CSF.

We studied the potential usefulness of CSF treponemal tests in the diagnosis of neurosyphillis. The CSF was tested with the microhemagglutination test for Treponema pallidum (CSF-MHA-TP test) and with the CSF-FTA test by using undiluted CSF and CSF diluted in saline and in sorbent. In a prospective evaluation, of 177 nonsyphilitics, none had reactive CSF-MHA-TP tests and only one had a reactive CSF-FTA test. However, five of 15 syphilitics with no other evidence of neurosyphilis had reactive CSF-FTA tests. The CSF-FTA test reactivity appeared most likely when the titer of the serum FTA test was high. In a retrospective evaluation of syphilitics with reactive CSF-FTA tests, similar patterns of reactivity occurred in patients with and without other evidence of neurosyphilis. Without other supporting clinical or laboratory data, the diagnostic value of a reactive CSF-FTA test is unknown.

Adult↗
PubMed1977

The FTA-ABS test: a diagnostic help or hindrance?

The fluorescent treponemal antibody absorption (FTA-ABS) test, an excellent confirmatory treponemal test, has been used increasingly for syphilis screening and case detection. To evaluate its performance as an initial test, we did Venereal Disease Research Laboratory (VDRL) slide and FTA-ABS tests on 1,043 patients suspected of having syphilis. When retested in both a local and a reference laboratory, sera from 226 patients with borderline or reactive results demonstrated interlaboratory consistency for the VDRL but not the FTA-ABS. Borderline FTA-ABS results correlated poorly with the diagnosis of syphilis in both laboratories; a reactive FTA-ABS test correlated well only in the reference laboratory. Performance of the test appeared to be diminished by its use in a low-prevalence population and by seemingly minor alterations in the test procedure at the local laboratory.

Absorption↗
PubMed1977

Use of stable, sensitized cells in an indirect microhemagglutination test for melioidosis.

Two evaluations were carried out in this study. The first was a comparison of the standard tube test with the automated microtitration test for the detection of antibodies to Pseudomonas pseudomallei by the indirect hemagglutination method. Data from this comparison indicated that the tests were equivalent. The second evaluation consisted of reproducibility studies on two lots of pyruvic aldehyde-stabilized sensitized erythrocytes in comparison with freshly prepared sensitized erythrocytes in the automated microtitration test. The influence of different types of the microtitration plates used was also examined. Results indicated that the use of stabilized antigens is feasible, and these antigens offer the advantage of being ready for immediate use.

Animals↗
PubMed1976

Immunoglobulin specificity for the fluorescent treponemal antibody-absorption test conjugate.

Quantitative indirect immunofluorescence tests have demonstrated the predominance of immunoglobulin G antibody in most stages of syphilis. A class-specific anti-human immunoglobulin G conjugate is recommended to replace the present fluorescent treponemal antibody-absorption test conjugate. This would allow further definition and standardization of the fluorescent treponemal antibody-absorption test.

Antibody Specificity↗