A simple and highly sensitive radioenzymatic assay for lysophosphatidic acid quantification

The objective of the present work was to develop a simple and sensitive radioenzymatic assay to quantify lysophosphatidic acid (LPA). For that, a recombinant rat LPA acid acyltransferase (LPAAT) produced in Escherichia coli was used. In the presence of [(14)C]oleoyl-CoA, LPAAT selectively catalyzes the transformation of LPA and alkyl-LPA into [(14)C]phosphatidic acid. Acylation of LPA was complete and linear from 0 to 200 pmol with a minimal detection of 0.2 pmol. This method was used to quantify LPA in butanol-extracted lipids from bovine sera, as well as from human and mouse plasma. This radioenzymatic assay represents a new, simple, and highly sensitive method to quantify LPA in various biological fluids.

Establishment of a nonradioactive assay for2’-5’ oligoadenylate synthetase and its application in chronic hepatitis C patients receiving interferon-α

AIM: To establish a nonradioactive assay for 2’-5’ oligoadenylate synthetase (2-5 AS) and to measure the 2-5AS in peripheral blood mononuclear cell (PBMC) extracts of patients with chronic hepatitis C before IFN-α injection, 24 h and one month after the first injection.

METHODS: 2-5AS in cell extracts of PBMCs from 10 normal persons and 15 chronic hepatitis C patients were determined with PEI cellulose thin-layer chromatography.

RESULTS: The assay of 2-5AS in human PBMC was found to be rapid, sensitive, specific and reliable. The 2-5AS activity of PBMC in normal persons was in a quite low level (2.0%), and it was increased about ten-folds after stimulation of IFN (19.7%), (P < 0.01). In 15 chronic hepatitic C patients, the basal levels of 2-5AS before IFN treatment were higher than those of normal persons, being much higher in the group showing poor response to IFN treatment, but 24h after the first injection of IFN-α the 2-5AS level showed a more rapid and much greater rise in those patients with a good response.

CONCLUSION: 2-5AS may be a useful parameter of biological response during the IFN therapy.