title: Stability of the paraoxonase phenotyping ratio in collections of human sera with differing storage times.
abstract: Results from automated testing of 673 human sera, divided into four batches by duration of storage at -20 degrees C, indicated that paraoxon-hydrolysing activity, a, decreased with increased storage time. By contrast, the paraoxonase phenotyping ratio, c/b, a ratio designating enzyme activation by Na+ in the presence of Ca2+, was stable over a four year storage period.
mesh_terms: D043303:Aryldialkylphosphatase; D001793:Blood Preservation; D005828:Genetics, Population; D006801:Humans; D010261:Paraoxon; D010641:Phenotype; D010744:Phosphoric Monoester Hydrolases / Q000097:blood* / Q000235:genetics; D013997:Time Factors
chemical_list: D010744:Phosphoric Monoester Hydrolases; D043303:Aryldialkylphosphatase; D010261:Paraoxon