Assay of α-difluoromethylornithine in body fluids and tissues by automatic amino-acid analysis

A procedure is described for the measurement of -α-difluoromethylornithine (DFMO), a selective irreversible inhibitor of ornithine decarboxylase, in biological specimens. The drug is separated from other amino acids with a commercial amino-acid analyser and detected by formation of its alkylthio-isoindole derivative with o-phthalaldehyde. DFMO concentrations of 0.1 nmol can be determined in a sample volume of 100 μl. The assay has been used to determine the half-life of DFMO in serum of several species and the relationships between serum and tissue concentrations.     

Cytokine measurements in body fluids

Bioassays and immunoassays for cytokines are now widely available for use in clinical laboratories which may have little or no expertise in cytokine biology. Whilst this facilitates the accumulation of data concerning cytokine levels in body fluids in disease, it is based on the assumption that such assays can be used for this purpose. In many cases, the presence of complex interfering factors in plasma and other body fluids require that assays should be subjected to detailed assay validation before confidence can be placed on the results. It is the purpose of this report to outline the potential problems with cytokine assays and the criteria that should be applied before making measurements in biological fluids.