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Biomedical subjects

B Christian

Publications and source records attributed to B Christian.

9 recordsLinked to original sources
PubMed1979

Isolation and partial characterization of the multiple forms of deoxyribonucleic acid-dependent ribonucleic acid polymerase in the fungus Podospora anserina.

Three DNA-dependent RNA polymerases have been isolated and partially purified from the mycelium of the fungus Podospora anserina. Separated by DEAE-Sephadex chromatography, they have been designated RNA polymerases I, II, and III according to their order of elution. Their catalytic properties and alpha-amanitin sensitivity are in agreement with those of the homologous enzymes found in other eukaryotic organisms. The three enzymes exhibit rather sharp monophasic ammonium sulfate dependence with optima which are, respectively, 0.035 M, 0.050 M, and 0.075 M. Enzyme I has the largest Mn2+/Mg2+ activity ratio, shows a marked preference for native DNA, and is insensitive to alpha-amanitin. Enzyme III uses poly(dA-dT) in preference to native DNA as template and is only partially sensitive to alpha-amanitin. Enzyme II is sensitive to alpha-amanitin, but high concentrations of the toxin are required for inhibition compared to other eukaryotic class II enzymes. Three similar RNA polymerases with comparable levels of activity were found in the temperature-dependent VR strain when cellular incompatibility, leading to a rapid cessation of RNA synthesis, was induced.

Amanitins↗
PubMed1977

Immunofluorescent technique for the detection of antibodies to n-DNA: comparison with radioimmunoassay.

One hundred and six sera from patients with systemic lupus erythematosus (SLE), 20 from patients without SLE but with a positive FANA, and 50 controls were tested for the presence of antibodies to n-DNA, using an immunofluorescent technique with the kinetoplast of Crithidia luciliae as a substrate. A high degree of correlation existed between the results obtained with this technique and a Millipore radioimmunoassay method using a well characterized tritiated native human DNA. The result with the immunofluorescent method could be expressed semiquantitatively as a titer, if serial serum dilutions were used. Results in patients with SLE correlated well with disease activity. We conclude that the immunofluorescent technique can provide a useful alternative to a radioimmunoassay for the detection of antibodies to n-DNA. In addition, as this substrate is known to contain pure n-DNA, problems do not arise with contamination with singlestranded DNA as sometimes occurs with other test antigens. This avoids the detection of antibodies reacting only with single-stranded areas and consequently increased the specificity of the reaction.

Antibodies, Antinuclear↗
PubMed1969

Sodium ions and the secretion of catecholamines.

1. Perfusion of bovine adrenal glands with a potassium-free Tyrode solution results in an increased spontaneous release of catecholamines and an increased response to stimulation with carbamylcholine.2. Perfusion with a Tyrode solution containing 70 mM-KCl causes a marked secretion of catecholamines and a subsequent inhibition of secretion in response to stimulation with carbamylcholine.3. Perfusion with sodium-free media abolishes or severely reduces the secretory response of the gland to carbamylcholine and to 70 mM-KCl although the basal secretion shows an initial rise.4. Perfusion with sodium-deficient media permits some retention of the secretory response.5. A possible role for intracellular sodium ions in the secretion of catecholamines is discussed.

Adrenal Glands↗