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Biomedical subjects

D Burger

Publications and source records attributed to D Burger.

At least 127 records · Page 7Linked to original sources
PubMed1979

Purification of the subunit Clq from the first component of equine complement.

Initial separation and concentration of Clq from fresh, normal equine serum was accomplished by precipitation in 0.02 M acetate buffer, pH 5.5, at 4 degrees for 24 h. The re-dissolved precipitate was clarified by centrifugation at 80,000 g for 1 h and then dialysed against Tris-HCl buffer (0.05 M, pH 8.0) containing 10-3 M EDTA. The clarified dialysate remained biologically active at 5 degrees for at least 4 weeks. Biological activity of equine Clq was determined by assay of its ability to agglutinate sensitized sheep erythrocytes (EA). Following ammonium sulphate fractionation, Sepharose 4B gel filtration yielded three major peaks. Two protein bands were demonstrated on analysis of the second Sepharose peak by disc acrylamide electrophoresis, pH 8.3. Elution of the protein bands showed EA-agglutinating activity only in the band which migrated furthest toward the cathode. Equine Clq isolated by this method yielded an approximate forty-fold purification in specific activity. Some properties of equine Clq were characterized. Equine Clq was heat-labile, as shown by loss of its EA-agglutinating activity after heating 58 degrees for 15 min. Moreover, storage at 4 degrees and freeze-thaw cycles greatly reduced EA agglutination. Preliminary determination of the sedimentation coefficient indicated that it was comparable to that reported for human and rabbit Clq.

Amino Acids↗
PubMed1977

Observation on the remarkable stability of transmissible mink encephalopathy virus.

Transmissible mink encephalopathy (TME) virus retained biological activity after prolonged storage in formalin (about three and a half years) and in paraffin tissue blocks used for histologic preparations (about six and a half years). Thus, TME tissues in formalin and in paraffin blocks should be handled as contaminated materials.

Animals↗
PubMed1976

Isolation of C1q-binding immune complexes by affinity chromatography and desorption with a diaminoalkyl compound.

The applicability of affinity chromatography to the isolation of C1q-binding immune complexes (IC) in sera was explored. Purified human C1q was covalently coupled to agarose or adsorbed to IgG-agarose resins. Sera containing preformed virus-antibody complexes or rheumatoid arthritis (RA) sera were passed through the columns and C1q-bound IC, eluted off with 1,4-diaminobutan at mild basic conditions, were analysed by immunodiffusion, crossed immunoelectrophoresis, gel filtration and electron microscopy. Under conditions of antibody treatment which caused almost 100% inhibition of virus plaque formation, about 30% of formed 14C-labelled equine arteritis virus-antibody complexes was bound specifically to and desorbed from C1q-IgG agarose columns. Studies with RA-sera indicated the presence of both IgM-IgI and intermediate size IgG, C1q-binding, complexes in 3 out of 5 tested seropositive sera. In two sera only intermediate size IC were demonstrable. The results obtained in these two IC model systems suggested that the described methods could be useful for isolation of C1q-binding IC in general.

Antibodies, Viral↗