Abstract
Isoprostanes (IsoPs) are key biomarkers for investigating the role of free radical generation in the pathogenesis of human disorders. To solve IsoPs-related problems with regard to isoprostanes, analytical tools are required. This paper reviews the problems and trends in this field focusing on the methodology for assaying biomarkers in exhaled breath condensate (EBC) samples. A large amount of work has been done in the qualitative and quantitative analysis of IsoPs, but a standardized method has yet to emerge. The methodologies described differ, either in the sample preparation steps or in the detection techniques, or both. Requiring a number of chromatographic steps, the relevant extraction and purification procedures are often critical and time-consuming, and they lead to a substantial loss of target compounds. Recent data show that EBC is a promising non-invasive tool for the evaluation of different diseases. Two main analytical approaches have been adopted for IsoPs measurement: immunological methods and mass spectrometry. The methodologies for the extraction, purification and analysis of IsoPs in EBC samples are presented.
Highlights
In recent years, oxidative stress has been implicated in various pathological situations
Lung oxidative stress is increased in children who are in a stable condition with asthma. 8-IsoP was detectable in the exhaled breath condensate (EBC) of healthy children, but elevated levels were found in both steroid-naive asthmatic children and steroid-treated asthmatic children [31]
Silicosis is a chronic occupational disease caused by the inhalation of crystalline silica particles for prolonged periods, which produces inflammation and tissue destruction followed by remodeling of the extracellular matrix. 8-isoPGF2α has been seen to increase in bronchoalveolar lavage in subjects with interstitial lung diseases, such as cryptogenic fibrosing alveolitis, and recently in EBC of such patients [15,35]
Summary
Oxidative stress has been implicated in various pathological situations. The oxidized lipids formed during lipid peroxidation, illustrate these problems (Figure 1) Among these markers areprimary‘ products such as hydroperoxides, orsecondary‘ products such as malondialdehyde (MDA), 4-hydroxynonenal (4-HNE) and isoprostanes (IsoPs). Nitrite (NO2−), ionized and not volatile, may arise in EBC in part from a reaction of volatile nitric oxide gas (NO) after reaction with oxygen [23] Volatiles such as acetic acid, formic acid and ammonia are found in much higher concentrations in EBC than non-volatile constituents, and are much easier to measure. The number of articles on EBC analysis has increased tenfold in the last 10 years
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