Biomedical subjects

D A Palmer

Publications and source records attributed to D A Palmer.

At least 19 recordsLinked to original sources

PubMed1992

Flow injection electrochemical enzyme immunoassay for theophylline using a protein A immunoreactor and p-aminophenyl phosphate-p-aminophenol as the detection system.

A competitive electrochemical enzyme immunoassay has been developed for the antiasthmatic drug theophylline, utilizing a controlled-pore glass-protein A immunoreactor and flow injection techniques. p-Aminophenyl phosphate, a substrate for alkaline phosphatase, has been used in this assay, and its hydrolysis product p-aminophenol was determined at +0.2 V versus the saturated calomel electrode. For each sample the antibody-protein A reaction takes place at near-neutral pH, and the complexes are eluted at acid pH. Serum theophylline has been determined by this method, and good relative standard deviations and percentage recoveries have been achieved.

Alkaline Phosphatase↗

PubMed1991

Flow injection immunoassay using a protein A immunoreactor.

Competitive immunoassays have been developed for the immunosuppressant cyclosporin A and the anti-asthmatic drug theophylline utilizing identical controlled pore glass-protein A microcolumns and flow injection techniques. For cyclosporin A the assay was based on a monoclonal antibody with fluorescence detection whilst for theophylline sheep antiserum and electrochemical detection was used.

Cyclosporine↗

PubMed1989

Analysis of Brucella lipopolysaccharide with specific and cross-reacting monoclonal antibodies.

Monoclonal antibodies which bind Brucella A lipopolysaccharide (LPS)-specific, M LPS-specific, or cross-reactive epitopes were used as reagents in quantitative dot blot, Western blot (immunoblot), and immunoprecipitation analysis of Brucella whole cells, whole-cell extracts, and purified LPS preparations. This set of monoclonal antibodies detected four unique epitopes on Brucella LPS. The specificity of monoclonal antibodies reactive with Brucella unique (A and M) and common (C and C/Y) LPS epitopes was demonstrated by blot analysis. The serotype specificity of monoclonal antibodies for A LPS of B. abortus 1119.3 or M LPS of Brucella melitensis 16M was confirmed. Type C monoclonal antibodies recognized epitopes on Brucella A and M LPS and did not cross-react with Yersinia enterocolitica O:9. In Western blots, type C monoclonal antibodies were bound by epitopes on Brucella A and M LPSs ranging in Mrs from 30,000 to 70,000, relative to marker proteins. Type C/Y monoclonal antibodies were cross-reactive with Y. enterocolitica O:9 and recognized Brucella A LPS epitopes with a restricted Mr ranging only from 40,000 to 50,000, relative to marker proteins. Type C/Y monoclonal antibodies also displayed a more restricted pattern of binding to Brucella M LPS. The monoclonal antibodies were able to detect 5 to 50 pg of a purified A LPS preparation in dot blots. The limits of detection by the monoclonal antibodies of a purified M LPS preparation ranged from 0.05 to 50 pg. Monoclonal antibody analysis of whole-cell preparations also demonstrated quantitative differences in the presence of the respective epitopes. The binding profiles of the monoclonal antibodies to Brucella whole cells varied between acetone- and chloroform-killed organisms as well as between species and strains. The lower limit of detection of any whole-cell preparation by the dot blot technique was 10(5) CFU. Binding profiles in Western blots and endotoxin activity of immunoprecipitates obtained with these monoclonal antibodies further defined the Brucella LPS antigens. These monoclonal antibodies and the techniques described may be useful in monitoring the antigenic content of Brucella vaccines and diagnostics.

Antibodies, Bacterial↗

PubMed1988

Use of monoclonal antibodies to identify the distribution of A and M epitopes on smooth Brucella species.

The smooth types of Brucella species express two lipopolysaccharides (LPSs) (A and M) which are antigenically distinct. Their existence as cross-reactive antigenic complexes makes definitive serology difficult. Murine hybridomas were produced and selected for their ability to produce monoclonal antibodies to the specific A- or M-LPS epitopes. The specificity of the monoclonal antibodies was determined by microplate enzyme-linked immunoassay, binding inhibition assay, microplate agglutination, and dot blot assay. Monoclonal antibody 12AE6 was specific for an epitope on the A LPS of Brucella spp., which was also expressed on Yersinia enterocolitica O:9. A unique epitope of M LPS was detected by monoclonal antibody 33.1.5. The two monoclonal antibodies did not exhibit cross-reactions when assayed with whole Brucella cells or purified M- and A-LPS preparations. Cross-reactive serology with polyvalent sera can be attributed to the presence of common antigenic determinants on both molecules. The use of A- and M-LPS-specific monoclonal antibodies has the potential to replace the more laborious methods involved in the production of monospecific sera.

Animals↗

PubMed1985

The scotopic visibility curve and cone intrusion.

The scotopic visibility curves of two observers have been measured by determining their absolute thresholds for monochromatic lights and by direct comparison matching just above the threshold, in a 10 degree field with its centre 15 degrees above the fixation point. The results were all similar to the CIE scotopic curve. However, the threshold results in the long-wave part of the spectrum could be considerably modified by subliminal red and green lights. This is consistent with Drum's observations of sub-additivity at threshold. Above threshold, supra-additivity was obtained. A scotopic curve is evidently a non-linear combination of rod and cone responses which varies with the conditions of observation.

Color↗

PubMed1985

Visibility curves by direct comparison in a 10 degree field at 1000 Td.

Twenty-four observers matched monochromatic lights to a white reference light in a 10 degree field. The retinal illuminance was 1000 Td over most of the spectrum. Twelve persons' visibility curves were more or less additive and resembled the y10 color-matching function of the CIE. Eight others had a double-peaked function, which failed badly to obey Abney's law. The remaining four were more additive, although their curves were broader than y10.

Adolescent↗

PubMed1982

Cryopreservation of Babesia bovis for in vitro cultivation.

The most efficient procedure for cryopreserving viable Babesia bovis organisms for in vitro cultivation consists of freezing extracellular parasites in a solution of 10% (w/v) polyvinylpyrrolidone (PVP) using a cooling rate of 20 degrees C/min. Although cultures can be established from thawed infected erythrocytes, the plating efficiency is relatively low. Freezing extracellular parasites resulted in plating efficiency up to 25%, when thawed and placed in culture. Glycerin or dimethyl sulphoxide (Me2SO) can be used successfully in the cryopreservation of B. bovis but apparent toxic effects greatly decrease their efficiency. B. bovis parasites have been kept to -196 degrees C for 60 days with no appreciable reduction in plating efficiency.

Animals↗

PubMed1980