Oldrich K. Sebek

Development of a GC-MS method for quantitation of 2, 3-dinor-TXB2 and determinations of the daily urinary excretion rates in healthy humans

Tetradeuterated 2,3-dinor-thromboxane B2 (2,3-dinor-TxB2) of high isotopic purity was prepared. This compound was used as internal standard in the development of a method for quantitation of 2,3-dinor-TxB2 in human urine based on gas chromatography--mass spectrometry with multiple ion detection. The accuracy of the method is about +/- 5% at the levels encountered when urine from normal healthy individuals was analyzed. The daily urinary excretion of 2,3-dinor-TxB2 in twenty normal healthy males and females was 457 +/- 210 (mean +/- SD) and 444 +/- 160 (mean +/- SD) ng/24 hrs respectively. The diurnal and day-to-day variations were found to be relatively small.

Preparation of two dinor-PGI2 metabolites from 6-keto-PGF1α by mycobacterium rhodochrous

Abstract The transformation of 6-keto-PGF1α to two prostacyclin metabolites, 2,3-dinor-6-keto-PGF1α (I) and 2,3-dinor-6,15-diketo-13,14-dihydro-PGF1α (II) by Mycobacterium rhodochrous UC-6176 is described. The finding that the bacterium oxidized 6-keto-PGF1α to the 6,15-diketo metabolite II shows that it contains 15-hydroxy prostaglandin dehydrogenase and Δ13 reductase enzyme systems.

Synthesis of thromboxane B2 metabolites

This paper reports the synthesis of 11-dehydrothromboxane B2 methyl ester (II), 15-dehydrothromboxane B2 methyl ester (III), 15-dehydro-13, 14-dihydrothromboxane B2 (XII) and 2,3-dinorthromboxane B2 methyl ester (XV). These compounds, as their free acids, have been reported to be thromboxane metabolites.

The synthesis of neomycin-C14 by Streptomyces fradiae.

Abstract When glucose uniformly labeled with carbon-14 was added to a growing culture of Streptomyces fradiae, 68.4 % of the total radioactivity was recovered in the respiratory carbon dioxide, 19.5 % was incorporated into neomycin, and the rest was distributed in the culture fluid and in the mycelium. Since the addition to the media of several compounds other than glucose resulted in an increased amount of this antibiotic, their labeled forms might possibly be considered as potential precursors of radioactive neomycin.

Biosynthesis of C14-Labeled Benzylpenicillin

Summary The biosynthesis of the C14 labeled benzylpenicillin was achieved by preparing phenylacetic acid-l-C14. and incorporating the latter into the side-chain of benzyl-penicillin. The antibiotic was successfully separated from the nonreacted labeled phenylacetic acid by column chromatography. The data obtained by radioautography and chemical degradation of the purified antibiotic indicated that the radioactivity resided in the side-chain of the benzylpenicillin molecule.

Roundtable Discussion of Research Priorities

The purpose of this panel is to discuss some future research needs and priorities in the area of genetic engineering of microorganisms.