Original Articles
Effect of age on the breath methylated alkane contour, a display of apparent new markers of oxidative stress,☆☆

https://doi.org/10.1067/mlc.2000.108943Get rights and content

Abstract

Reactive oxygen species (ROS) are toxic byproducts of mitochondrial energy production that inflict oxidative stress, a constant barrage of damage to DNA, proteins, lipids, and other biologically important molecules. Oxidative stress has been implicated as a pathologic mechanism in aging and in several diseases. We developed a display of apparent new markers of oxidative stress in human beings, the breath methylated alkane contour (BMAC). The BMAC is a three-dimensional display of C4 to C20 alkanes and monomethylated alkanes in breath, with x-axis = carbon chain length, z-axis = methylation site, and y-axis = alveolar gradient (relative abundance in breath minus relative abundance in room air). In 102 normal human subjects of 9 to 89 years of age, alveolar gradients of components of the BMAC increased significantly with age. The mean alveolar gradient of all components of the BMAC varied from negative in the youngest quartile (ages 9 to 31 years) to positive in the oldest quartile (ages 74 to 89 years)(P < 2.10–9). These findings were consistent with an increase in oxidative stress with advancing age, although an age-related decline in clearance by cytochrome p450 may have contributed. The BMAC provides a display of apparent new markers of oxidative stress with potential applications in aging research, clinical diagnosis, pharmacology, and toxicology. (J Lab Clin Med 2000;136:243-9)

Section snippets

Collection of breath and air samples

VOCs in breath and room air were collected with a breath collection apparatus, a portable microprocessor-controlled device. Each subject wore a nose clip while inspiring and expiring through a low-resistance disposable mouthpiece into a wide-bore breath reservoir (1.0-inch diameter) open to the atmosphere at its distal end. The breath reservoir was heated to prevent condensation. Alveolar breath was pumped from the breath reservoir through a sorbent trap where the breath VOCs were captured on

Results

Seventy-three different C4 to C20 alkanes and monomethylated alkanes were observed at least once in the breath samples. Subjects, in groups of 25 or 26, were assigned to four quartiles according to their age, ranging from the first quartile (the youngest quarter of the population) to the fourth quartile (the oldest quarter of the population). Breath data were pooled from subjects in each quartile to determine their mean alveolar gradients of alkanes and monomethylated alkanes. These values were

Discussion

Our study demonstrated three main findings: (1) normal human breath contains a greater number of alkanes and monomethylated alkanes than previously reported; (2) the alveolar gradients of several of these VOCs were significantly more positive in older than in younger normal human beings; (3) the combined mean alveolar gradient of all VOCs in the BMAC significantly increased with age, from negative in the youngest to positive in the oldest.

To interpret these findings, two separate issues need to

Acknowledgements

We thank Donald A Brand, PhD, and Eugene Sersen, PhD, for their assistance in the preparation of this report.

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    Supported by National Institutes of Health Grant 1R41 RRHL13233-01.

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    Reprint requests: Michael Phillips MD, FACP, Menssana Research Inc, 1 Horizon Rd, Suite 1415, Fort Lee, NJ 07024.

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