Biomedical subjects
Publications and source records attributed to R W Stevens.
Serum alpha-fetoprotein (AFP) in hepatoma BW7756-bearing mice was measured by a new particle agglutination inhibition test employing AFP adsorbed to charcoal particles. The AFP levels and tumor weights showed nearly parallel increases to means of 2633 microgram/ml and 5.2 g, respectively, 28 days after implantation.
Explore the source record for details and available documents.
Special solid-phase fluoroimmunoasssay protocols were used to measure the amount of immunoglobulin G (IgG) and albumin in 1,511 samples of cerebrospinal fluid. The fluoroimmunoassay is an inhibition test conducted on the surface of a plastic probe, whose fluorescence is inversely related to the concentration of spinal fluid IgG or albumin. A microcomputer interfaced with the fluorometer calculates the sample IgG or albumin from a calibration curve based on standard cerebrospinal fluid values. The test and interpretation take less than 90 min. Correlation coefficients for over 100 cerebrospinal fluid samples tested by both fluoroimmunoassay and radial immunodiffusion were: IgG, 0.90 (slope, 1.04); albumin, 0.95 (slope, 0.99). The within-run precision (coefficient of variation) was: IgG, 4.4%; albumin, 6.3%. Run-to-run precision on a midrange sample was: IgG, 7.7%, albumin, 11.7%. These findings establish the simplicity, speed, and precision of the modified fluoroimmunoassay system for specific cerebrospinal fluid proteins.
Only 4.2% of 284 single specimens and 17.6% of 51 pairs of sera reactive in Weil-Felix agglutination tests for Rocky Mountain spotted fever were confirmed by a specific Rickettsia rickettsii microimmunofluorescence test.
The macroscopic rapid plasma reagin (RPR) and reagin screen (RST) card tests for syphilis were compared. Test specimens were also examined with the Venereal Disease Research Laboratory (VDRL) microscopic slide test; those reactive in the card or slide tests were examined with the fluorescent treponemal antibody-absorption (FTA-ABS) procedure. Agreement between the card tests with 2,300 specimens was 99%; among all three reagin tests it was 96.3%. With 348 specimens reactive in one or more of the tests, there was 75.6% agreement among all three tests. The FTA-ABS was reactive with 71% of the RPR- or RST- and 65% of the VDRL-reactive specimens. The comparison showed that the card tests give results in close agreement with those of VDRL while offering a number of practical advantages over it.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A simple, rapid hepatitis B antigen card test (card test III) with third-generation sensitivity has been developed. This test is a modification of the charcoal-particle agglutination-inhibition procedure. Sera from voluntary blood donors and hospital patients were tested by the new procedure, by the original inhibition technic, by reversed passive hemagglutination, and by radioimmunoassay. This comparison showed that CT III has a specificity equal to that of radioimmunoassay and is almost as sensitive.
Specific aggregation of latex particles due to antigen-antibody reaction occurred only when antigen was latex bound, as found in a study using Escherichia coli 0111:B4 extract. Maximum serological sensitivity was achieved when free antigen was present in a narrow range of ratios with the bound antigen.
A latex particle agglutination technique to detect ethylenediaminetetraacetate-solubilized extracts from Escherichia coli and whole E. coli cells is described. The sensitivity of the serological test was found to be 0.5 to 2.5 ng for the solubilized antigens and 1.5 x 10(6) to 5.7 x 10(6) cells per ml for the particulate antigens. The test was 100 to 1,000 times more sensitive than the standard bacterial agglutination test. Furthermore, it detected E. coli antigens during all phases of bacterial growth, whereas the bacterial test detected the antigens only after the mid-log phase. No significant cross-reactivity was observed between latex-anti-E. coli preparations and heterologous bacterial strains used in the experimental procedure. A buffer formula containing fatty acid-free bovine albumin prevented nonspecific aggregation of the latex particles.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.