Sagayama Hiroyuki, Racine Natalie M, Shriver Timothy C, Schoeller Dale A
Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan.
Biotechnology Center, University of Wisconsin, Madison, Wisconsin, USA.
Rapid Commun Mass Spectrom. 2021 Nov 15;35(21):e9188. doi: 10.1002/rcm.9188.
This study determines if saliva collection procedures for the doubly labeled water (DLW) method, used for measuring total energy expenditure (TEE), are comparable to urine and plasma collection. Both the cavity ring-down spectroscopy (CRDS) and isotope ratio mass spectrometry (IRMS) analyses techniques are compared.
Saliva specimens were collected from participants for the DLW method. The specimens were collected under different conditions: after consumption of tap water, after chewing gum, and during exposure to conditions of high and low relative humidity. The isotopes in saliva were compared with simultaneous plasma and urine collection. TEE calculated from saliva and analyzed using CRDS was compared to that of plasma analyzed using IRMS.
The within-individual variances were not significantly different between the saliva specimens (0.4‰) and plasma (0.3‰). After the oral dose of DLW, the saliva specimens displayed a shorter equilibration time to urine. When participants consumed 500 mL of tap water, the enrichment of saliva specimens reached a new plateau value faster than urine. Saliva collection exposed to high ambient humidity conditions was slightly less enriched as compared to low-humidity conditions while urine enrichment was unaffected. In contrast, whereas the within-individual effects of gum chewing during saliva collection on O were unaffected, the abundance of H in saliva was slightly lower after chewing the gum. The within-individual difference between TEE calculated from saliva and that calculated from plasma analyzed using IRMS did not differ from zero, and the standard deviation was not different from that predicted by a propagation of error analysis based on analytical error alone.
Our findings support using saliva specimens for the DLW method. The analysis of plasma and urine, however, requires reducing the memory effect resulting from contaminants. Also, it should be performed in a manner that minimizes exposure to air where specimens may be exposed to evaporation or contamination from water vapor during sampling.
本研究旨在确定用于测量总能量消耗（TEE）的双标记水（DLW）法的唾液采集程序是否与尿液和血浆采集具有可比性。同时比较了腔衰荡光谱法（CRDS）和同位素比率质谱法（IRMS）这两种分析技术。
采集参与者的唾液样本用于DLW法。样本在不同条件下采集：饮用自来水后、咀嚼口香糖后以及在高、低相对湿度条件下暴露期间。将唾液中的同位素与同时采集的血浆和尿液进行比较。将通过CRDS分析从唾液中计算出的TEE与通过IRMS分析血浆得出的TEE进行比较。
唾液样本（0.4‰）和血浆样本（0.3‰）的个体内方差无显著差异。口服DLW后，唾液样本达到与尿液平衡的时间更短。当参与者饮用500毫升自来水时，唾液样本的富集比尿液更快达到新的平稳值。与低湿度条件相比，高环境湿度条件下采集的唾液样本富集程度略低，而尿液富集不受影响。相比之下，唾液采集过程中咀嚼口香糖对氧的个体内影响未受影响，但咀嚼口香糖后唾液中氢的丰度略低。从唾液计算得出的TEE与通过IRMS分析血浆计算得出的TEE之间的个体内差异与零无差异，且标准差与仅基于分析误差的误差传播分析预测的标准差无差异。
我们的研究结果支持将唾液样本用于DLW法。然而，血浆和尿液分析需要减少污染物产生的记忆效应。此外，分析应尽量减少样本在采样期间暴露于空气中，因为样本可能会因蒸发或水蒸气污染而受到影响。
