title: Age dependence of tissue plasminogen activator concentrations in plasma, as studied by an improved enzyme-linked immunosorbent assay.
abstract: A procedure for improving the specificity of enzyme-linked immunosorbent assays (ELISA) was devised, based on addition of antigen-specific or non-immune immunoglobulins to the citrated plasma sample and defining the difference in assay response between these two mixtures as the antigen-specific part of the response. When applied to measurement of tissue plasminogen activator (t-PA; EC 3.4.21.31) antigen in plasma, this procedure resulted in elimination of the overestimates obtained in a large proportion (10-20%) of patients' samples when assayed according to the conventional ELISA technique. Basal t-PA concentrations in plasma were found to be highly age-dependent, normal values being about 3 micrograms/L for adults near 30 years of age and about 10 micrograms/L for those over 60. Patients with gallbladder stone disease had increased mass concentrations of t-PA in plasma, even when corrected for the age effect; patients with multi-infarct dementia did not.
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood*; D000941:Antigens / Q000032:analysis; D002769:Cholelithiasis / Q000097:blood; D003704:Dementia / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D010959:Tissue Plasminogen Activator / Q000097:blood* / Q000276:immunology
chemical_list: D000941:Antigens; D010959:Tissue Plasminogen Activator