Xanthine oxidase activity in human liver or jejunum homogenates was measured by using 8-^14 C-hypoxanthine (HX) as a substrate. Products of oxidation were separated by thin-layer chromatography on MN Polygram cellulose and located by autoradiography. The percentage of oxidation was measured by liquid scintillation. Main parameters of the enzyme reaction have been optimized. Repeatability and reproducibility of the overall procedure give a variation coefficient of 6.3 and 7.7%, respectively. Minimal detectable enzymatic activity corresponds to an oxidation percentage of 1 % (HX) for liver and jejunum. The reliability and practicability of this method allow a rapid diagnosis of xanthine oxidase deficiency. Normal values obtained by this optimized method range between 25 and 42 μkat • kg^-1 protein for liver and 18 and 40 μkat -kg-1 protein for jejunum.

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Shallow-water assemblages of transported ("freshly reworked") bioclasts (mainly orbitolinids and dasycladales) are observed in the deeper facies of the "Vocontian Trough" (SE France). There these benthic assemblages can be directly correlated with ammonite zones. These new finds give an Early Barremian age to the earliest record of Palorbitolina lenticularis as well as those of four so-called "typical Early Aptian" representatives of the genus Orbitolinopsis. Actually most orbitolinid species recorded from the Late Barremian interval are now found present in Lower Barremian strata at L'Estellon. Some currently used correlation schemes for the Urgonian platforms, that are based on partial stratigraphic distribution ranges for the orbitolinids,-and consequently derived conclusions and hypotheses-require at least in-depth revisions when they are not definitively refuted.The study of the ammonite fauna in the L'Estellon section (Drôme department, SE France) allows us to date episodes with gravitational deposition in this area of the "Vocontian Trough". They span most of the Barremian Stage, from the Nicklesi Zone up to the Giraudi Zone. We did not identify any Bedoulian redeposits, the "Bedoulian ridge" auct. being latest Barremian in age.

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