From syndrome to spectrum: what evolution suggests about the status of the metabolic syndrome.

SAH after blood sample incubation over a period of 0, 2, 6, and 24 h at room temperature or at 4 °C. In the Primavette, Hcy obtained by HPLC decreased only slightly (Ϫ4.8%) after 6-h incubation at room temperature and returned to the baseline value after 24 h. At 4 °C a significant decrease of Hcy (6.9%) after 24-h incubation was found (P ϭ 0.003). Applying FPIA for the determination of Hcy, no significant changes of Hcy compared with the baseline values were found. However, the comparison between baseline Hcy determined by FPIA and HPLC revealed that Hcy values obtained by FPIA were significantly higher (median difference 11%) than values obtained by HPLC (P Ͻ0.001). In EDTA and acidic citrate plasma we observed no significant difference between Hcy obtained by FPIA and HPLC. The positive bias seen with Primavette tubes was likely due to interferences with the FPIA method by its proprietary components, which are kept secret by the manufacturer. In acidic citrate samples Hcy increased slowly at room temperature, reaching the level of significance after 6 h (FPIA) and 24 h (HPLC), respectively. At 4 °C Hcy was stable over a 24-h period. In EDTA tubes a strong increase of Hcy was observed that was markedly decreased at 4 °C. In the Primavette, SAM was stable at room temperature and at 4 °C. At room temperature SAM decreased in EDTA and to a smaller extent in acidic citrate tubes. This decrease was clearly decelerated at 4 °C. At room temperature SAH increased in all 3 collection tubes and reached the highest values in the Primavette after 24 h. The increase was attenuated at 4 °C. In Primavette and acidic citrate samples we observed 7-and 3-fold increases of plasma SAH after 24-h incubation at room temperature, whereas Hcy was stable and increased by 20%, respectively (geometric means). In EDTA samples SAH and Hcy increased 1.8-fold. Interestingly , the increase of SAH after 24 h correlated negatively with the increase of Hcy after 24 h in Pri-mavette and acidic citrate samples (r ϭ Ϫ0.647; P ϭ 0.002) but not in EDTA samples (r ϭ 0.067). Hcy is generated in erythrocytes from its precursor SAH by catalysis of SAH hydrolase. Therefore, the inhibition of SAH hydrolase activity causes an increase of SAH and no or low increase of Hcy. In contrast, in EDTA samples the increase of SAH is low because SAH …