Breath isoprene: temporal changes in respiratory output after exposure to ozone

Abstract

Isoprene is a major hydrocarbon found in human breath. This study was conducted to evaluate whether respiratory isoprene output could serve as a monitor for ozone exposure. Healthy young adult subjects (n = 10) underwent chamber exposure on separate days to filtered air and to a variable concentration of ozone. Exposures had durations of 130 min that included alternate periods of rest and light treadmill exercise; breath was sampled pre- and postexposure. For six subjects, breath was resampled 19 +/- 1 h postexposure. Breath samples were concentrated cryogenically and analyzed by capillary gas chromatography. Isoprene output immediately postexposure was significantly reduced by ozone or filtered air (17 and 19%, respectively). These results suggest that exercise alone reduces isoprene levels in breath without an additive ozone effect. However, in the six subjects restudied 19 +/- 1 h postexposure to ozone, breath isoprene concentrations were now increased above the preexposure output by 99% (P < 0.01) and exceeded the 51% increase in output of isoprene at this time point after filtered-air exposure (P < 0.01). Therefore, breath isoprene is proposed as a noninvasive marker of a physiological response to oxidant-induced injury to epithelial membranes and fluid linings of the lower respiratory tract by ozone.

Breath isoprene during acute respiratory exacerbation in cystic fibrosis

“…This may reflect different kinetics for damage to proteins and their appearance in the systemic circulation. In contrast to other workers who found increased breath isoprene in conditions associated with increased oxidative stress to lung epithelia the authors found decreased levels during acute respiratory exacerbation which increased towards normal, following treatment [20]. The ability to assess free radical damage/activity has always been compromised by limitations in the assays available.…”

Volatile organic compounds in the exhaled breath of young patients with cystic fibrosis

“…Other exhaled compounds have attracted attention in a medical context: Ethane and n-pentane were linked to the in vivo level of lipid peroxidation and oxidative stress [2][3][4], breath acetone was shown to correlate with the metabolic state of diabetic patients [5] or mice on a ketogenic diet [6], and a decrease in exhaled isoprene was reported shortly after ozone exposure [7] and in acute pulmonary exacerbations of cystic fibrosis (CF) [8]. Yet, despite a growing scientific focus on nitric oxide and other exhaled biomarkers of pulmonary disease [9,10], data on breath VOC remain scarce and important methodological questions unanswered, such as the standardised collection, handling and analysis of human breath samples.…”

Gases as Uremic Toxins: Is There Something in the Air?

“…31 Increases in isoprene concentrations in the breath have been observed in states of acute tissue injury such as myocardial infarction and acute lung injury. 32,33 A recent study on gas chromatographic breath analysis of uremic rats showed an early increase of isoprene after induction of kidney injury. 34 In human beings, current data indicate an increase of isoprene in the breath during a hemodialysis session.…”