title: A radiometric microbiologic assay for the biologically active forms at niacin.
abstract: A radiometric microbiologic assay has been developed for the determination of niacin in biologic fluids. Lactobacillus plantarum produced 14CO2 from L-[U-14C] hr malic acid in quantities proportional to the amount of niacin present. The assay is specific for the biologically active forms of niacin in humans. Thirty normal hemolysates were analyzed and the values ranged from 13.0 to 17.8 micrograms niacin/ml RBC (mean = 15.27 +/- 1.33 s.d.). Good recovery and reproducibility studies were obtained with this assay. On thirty blood samples, correlation was excellent between the radiometric and the conventional turbidimetric assays.
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods*; D001835:Body Weight / Q000187:drug effects; D002245:Carbon Dioxide / Q000378:metabolism; D002250:Carbon Radioisotopes; D007778:Lactobacillus / Q000254:growth & development / Q000378:metabolism; D008293:Malates / Q000378:metabolism; D009391:Nephelometry and Turbidimetry; D009539:Nicotinic Acids / Q000032:analysis / Q000097:blood*; D051381:Rats
chemical_list: D002250:Carbon Radioisotopes; D008293:Malates; D009539:Nicotinic Acids; D002245:Carbon Dioxide