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Biomedical subjects

C Johnston

Publications and source records attributed to C Johnston.

297 records · Page 17Linked to original sources
PubMedDate not supplied

Relative value of commercial kits for ANA testing.

AIMS: We have tested the relative performance of 20 commercial ANA test kits along with that of our own laboratory to assess whether one was clearly superior. METHODS: The sera were drawn from 3 pools that had all been pre-tested in our laboratory: patients with definite SLE; patients with non-connective tissue diseases (CTD), but where a positive FANA had been found; and normal blood donors. The tests were used in accordance with the recommendations of the specific supplier but in a routine serology laboratory. RESULTS: Sensitivity and specificity ranged between 38 and 100%. While the negative predictive value of 4 ELISA kits was 100%, and most others were close, the HEp-2 kits were 100% in only 1 case. A positive predictive value of 100% was also seen with 1 kit. CONCLUSION: Some of the tests are clearly better than others, but the choice may differ depending on the clinical needs, e.g. preference for a good positive or negative predictive value. However, the ELISA kits offered better results than the immunofluorescent technique. Two of them had sensitivity/specificity of > 90%.

Antibodies, Antinuclear↗
PubMedDate not supplied

The in vivo effect of nonsteroidal anti-inflammatory drugs, gold sodium thiomalate and methotrexate on neutrophil superoxide radical generation.

The generation of superoxide radicals by activated peripheral blood polymorphonuclear leukocytes from patients with rheumatoid arthritis (RA) has been measured and the in vivo effect of nonsteroidal anti-inflammatory drugs (NSAIDs) and disease remittive agents studied. Generation of superoxide radicals from RA patients was significantly decreased when compared to a control population. This was principally due to the disease rather than medications in that patients with osteoarthritis receiving NSAID generated superoxide radicals similar to that seen in the control group. RA patients receiving NSAIDs and injectable gold or methotrexate therapy showed a significant trend to normalization of superoxide radical generation when compared to those with RA receiving NSAIDs alone. We conclude that the reduced generation of superoxide radicals on activated polymorphonuclear leukocytes from patients with RA is principally a feature of the disease and that this abnormality can be partially reversed by the use of a disease remittive agent in vivo.

Adult↗
PubMedDate not supplied

The effect of in vivo and in vitro methotrexate on lymphocyte proliferation as measured by the uptake of tritiated thymidine and tritiated guanosine.

In several studies methotrexate therapy of patients with rheumatoid arthritis has not been found to depress the lymphocyte response to mitogens measured by the uptake of tritiated thymidine. We have postulated two effects of methotrexate on stimulated lymphocytes in vitro: a decrease in cell proliferation, but also a relative increase in thymidine uptake reflecting a specific decrease in the intracellular thymidine pool. The increased incorporation of tritiated guanosine by mitogen-stimulated lymphocytes was found to be markedly depressed by methotrexate (1 x 10(-7) M) in vitro whereas the incorporation of thymidine was often unchanged. Thymidine uptake of lymphocytes may not be an appropriate measure of stimulation in the presence of methotrexate.

Guanosine↗
PubMedDate not supplied

Congenital dislocation of the hip in the American black.

Between 1977 and 1982, 19 cases of congenital dislocation of the hip (CDH) were encountered in black infants. Six of these cases were associated with other anomalies (atypical CDH); 13 were typical CDH. The incidence of complete CDH in the white population studied is 1.5/1000; in the black population studied it is 0.46/1000. The increased incidence in comparison to previous studies may possibly reflect genetic heterogeneity in the control population relative to the African black.

Black or African American↗