Differential ion mobility spectrometry (DMS) is a method to detect volatile organic compounds (VOC) in the ppt range. This study assessed whether VOC analysis using DMS could discriminate subjects with an experimentally induced chronic intestinal infection caused by Mycobacteria from non-infected controls. The animal model consisted of two groups of goats orally infected with two different doses of Mycobacterium avium subspecies paratuberculosis (MAP) and one group of non-infected healthy controls (each group: n = 6). Using DMS, exhaled breath and headspace of feces were analyzed on-line on an individual basis 9 months after inoculation of MAP. Data analysis included peak detection, cluster analysis, selection of discriminating VOC features (Mann-Whitney U test), and classification using a support-vector-machine. Taking the background of ambient air conditions into account, VOC analysis of exhaled breath as well as of feces revealed significant differences between chronically infected animals and non-infected controls. In both specimens, increasing as well as decreasing VOC features could be attributed to infection. Discrimination between infected and non-infected animals was sharper analyzing exhaled breath compared to headspace of feces. In exhaled breath, at least two VOC features were found to increase in a dose-dependent manner with increasing doses of MAP inoculated. Results of this study provide strong evidence that DMS analysis of exhaled breath has the potential to become a valuable tool for non-invasive assessment of VOC specifically related to certain diseases or infections.

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Measurement of leukotriene E 4 (LTE 4 ) in urine is a noninvasive method for assessing changes in the rate of total body cysteinyl leukotriene production. Eosinophil protein X (EPX) has been used to assess eosinophil activity and monitor inflammation in bronchial asthma. The aim of the study was to look for differences in urinary LTE 4 and EPX concentrations between children with stable atopic asthma and healthy controls and to compare asthmatic children with different disease severity. In addition the relationship was evaluated between urinary LTE 4 amd EPX levels and lung function.LTE 4 was also measured (enzyme immunoassay) together with EPX (radioimmunoassay) in urine and lung function tests were carried out in children with mild asthma (steroid-naive) (n=49), moderate to severe asthma (using inhaled steroids) (n=31) and healthy control subjects (n=28).Urinary leukotriene E 4 (LTE 4 ) was significantly higher in children with asthma than in controls (median [25±75 percentile] 238.5 (126.5±375.7) SD 191.8 versus 189 (51±253.2) SD 131.7 pg . mg -1 creatinine; p=0.021). Urinary EPX was also significantly increased in asthmatic children compared with controls (85.5 [64±131.5] SD 76.2 versus 48.5 [43.2±90] 112.1 mg . mmol -1 creatinine; p=0.006). There were no differences in urinary LTE 4 and EPX between the group of mild and the group of moderate to severe asthmatic children. There were significant associations between the urinary LTE 4 and intrathoracic gas volume (ITGV), residual volume (RV), forced expiratory volume in one second (FEV1), forced expiratory capacity (FVC) and maximum expiratory flow rate at 25% of vital capacity (MEF25).Urinary EPX was only correlated with maximum expiratory flow rate at 75% of vital capacity (MEF75). Thus measurement of urinary LTE 4 may predict the degree of airflow obstruction in asthmatic children. Urinary LTE 4 and EPX are useful markers of airway inflammation and can be helpful in guiding asthma management. There was no correlation between LTE 4 and EPX levels. Eur Respir J 2000; 16: 588±592.

Collection of exhaled condensate is tolerated well by calves and is an acceptable method for obtaining fluid from exhaled air originating from the lungs. This method provides alternatives for diagnosing and evaluating treatment of naturally acquired and experimentally induced diseases of the lungs and airways in calves.

Monitoring free IgE and omalizumab serum concentrations in patients treated with omalizumab does not predict clinical response nor does it add to the decision to continue or stop treatment. However, routine measurements of free IgE may be clinically relevant to demonstrate an adequate reduction in free IgE in patients not responding to omalizumab therapy.