Lord Richard S
NGA Bioscience, Waleska, Georgia
Physiol Rep. 2016 Feb;4(4). doi: 10.14814/phy2.12706.
An investigation of human biological variation in urinary organic acids, including pyroglutamic acid along with 39 other compounds, was previously reported in which levels were determined for 8 weeks in healthy adult subjects. Here, unique, 4-week-long physiological trends for one of those compounds, pyroglutamic acid (PGA), are reported. When PGA levels for an individual rose above 40 μg/mg creatinine, 4-week downward progressions occurred until levels reached values near 15 μg/mg creatinine and the pattern was reversed when levels for an individual were below that level in the early weeks of the study. The pattern was especially prominent among 8 of the 13 menstruating female subjects suggesting a possible association with metabolic stress of the menstrual cycle. However, it also appeared in 3 of the 8 male subjects where other sources of metabolic stress may be present. The menstrual association is consistent with estrogen-mediated increase in oxidative stress. Since PGA is linked to glutathione turnover, the consistency of extreme values across all individuals displaying the pattern indicates that 15 and 40 μg/mg creatinine may represent limits that trigger shifts in sulfur amino acid metabolism. This is the first observation of approximate month-long cyclic responses in a glutathione-related urinary marker in humans.
此前有一项关于人类尿中有机酸生物变异的研究报道，其中包括焦谷氨酸以及其他39种化合物，该研究测定了健康成年受试者8周内这些物质的水平。在此，报告了其中一种化合物焦谷氨酸（PGA）独特的、为期4周的生理趋势。当个体的PGA水平升至40μg/mg肌酐以上时，会出现为期4周的下降过程，直至水平降至接近15μg/mg肌酐的值，而当个体在研究初期的水平低于该值时，模式则会逆转。这种模式在13名处于月经期的女性受试者中的8名身上尤为明显，提示可能与月经周期的代谢应激有关。然而，在8名男性受试者中的3名身上也出现了这种情况，他们可能存在其他代谢应激源。月经关联与雌激素介导的氧化应激增加相一致。由于PGA与谷胱甘肽周转有关，所有呈现该模式的个体中极值的一致性表明，15μg/mg肌酐和40μg/mg肌酐可能代表触发硫氨基酸代谢转变的界限。这是首次在人类中观察到与谷胱甘肽相关的尿标志物出现近似为期一个月的周期性反应。
