Ross Brian M, Babgi Randa
Northern Ontario School of Medicine and Department of Biology, Lakehead University, Thunder Bay, Ontario, Canada.
J Breath Res. 2017 Sep 13;11(4):046001. doi: 10.1088/1752-7163/aa7d10.
Breath analysis is a form of metabolomics that utilises the identification and quantification of volatile chemicals to provide information about physiological or pathological processes occurring within the body. An inherent assumption of such analyses is that the concentration of the exhaled gases correlates with the concentration of the same gas in the tissue of interest. In this study we have investigated this assumption by quantifying some volatile compounds in peripheral venous blood headspace, and in nasal breath collected in Tedlar bags obtained at the same time from 30 healthy volunteers, prior to analysis by selected ion flow tube mass spectrometry. Some endogenous compounds were significantly correlated between blood headspace and nasal breath, such as isoprene (r = 0.63) and acetone (r = 0.68), however many, such as propanol (r = -0.26) and methanol (r = 0.23), were not. Furthermore, the relative concentrations of volatiles in blood and breath varied markedly between compounds, with some, such as isoprene and acetone, having similar concentrations in each, while others, such as acetic acid, ammonia and methanol, being significantly more abundant in breath, and others, such as methanal, being detectable only in breath. We also observed that breath propanol and acetic acid concentrations were higher in male compared to female participants, and that the blood headspace methanol concentration was negatively correlated to body mass index. No relationship between volatile concentrations and age was observed. Our data suggest that breath concentrations of volatiles do not necessarily give information about the same compound in the blood stream. This is likely due to the upper airway contributing compounds over and above that originating in the circulation. An investigation of the relationship between breath volatile concentrations and that in the tissue(s) of interest should therefore become a routine part of the development process of breath-based biomarkers.
呼吸分析是代谢组学的一种形式，它通过对挥发性化学物质的鉴定和定量来提供有关体内发生的生理或病理过程的信息。此类分析的一个固有假设是，呼出气体的浓度与目标组织中相同气体的浓度相关。在本研究中，我们通过对30名健康志愿者同时采集的外周静脉血顶空和泰德拉袋中收集的鼻腔呼吸中的一些挥发性化合物进行定量，来研究这一假设，然后通过选择离子流管质谱法进行分析。一些内源性化合物在血顶空和鼻腔呼吸之间存在显著相关性，如异戊二烯（r = 0.63）和丙酮（r = 0.68），然而许多化合物，如丙醇（r = -0.26）和甲醇（r = 0.23），则不存在相关性。此外，血液和呼吸中挥发性物质的相对浓度在不同化合物之间差异显著，一些化合物，如异戊二烯和丙酮，在两者中的浓度相似，而其他化合物，如乙酸、氨和甲醇，在呼吸中的含量明显更高，还有一些化合物，如甲醛，仅在呼吸中可检测到。我们还观察到，男性参与者呼吸中的丙醇和乙酸浓度高于女性，并且血顶空甲醇浓度与体重指数呈负相关。未观察到挥发性物质浓度与年龄之间的关系。我们的数据表明，呼吸中挥发性物质的浓度不一定能提供有关血流中相同化合物的信息。这可能是由于上呼吸道除了循环中产生的化合物外还会产生其他化合物。因此，对呼吸挥发性物质浓度与目标组织中浓度之间关系的研究应该成为基于呼吸的生物标志物开发过程中的常规部分。
