Naděžda Machková

Quantification of pentane in exhaled breath, a potential biomarker of bowel disease, using selected ion flow tube mass spectrometry

RATIONALE Inflammatory bowel disease has a relatively large incidence in modern populations and the current diagnostic methods are either invasive or have limited sensitivity or specificity. Thus, there is a need for new non-invasive methods for its diagnosis and therapeutic monitoring, and breath analysis represents a promising direction in this area of research. Specifically, a method is needed for the absolute quantification of pentane in human breath. METHODS Selected ion flow tube mass spectrometry (SIFT-MS) has been used to study the kinetics of the O2(+) reaction with pentane. Product ions at m/z 42 and 72 were chosen as characteristic ions useful for the quantification of pentane and the reactivity of these ions with water vapour was characterized. A pilot study has been carried out of pentane in the exhaled breath of patients with Crohns disease (CD) and ulcerative colitis (UC) and of healthy volunteers. RESULTS Accurate data on the kinetics of the gas phase reaction of the O2(+•) ions with pentane have been obtained: rate coefficient 8 × 10(-10) cm(3) s(-1) (±5%) and branching ratios into the following product ions C5H12(+•) (m/z 72, 31%); C4H9(+) (m/z 57, 8%); C3H7(+) (m/z 43, 40%), C3H6(+•) (m/z 42, 21%). A method of calculation of absolute pentane concentration in exhaled breath was formulated using the count rates of the ions at m/z 32, 42, 55 and 72. Pentane was found to be significantly elevated in the breath of both the CD (mean 114 ppbv) and the UC patients (mean 84 ppbv) relative to the healthy controls (mean 40 ppbv). CONCLUSIONS SIFT-MS can be used to quantify pentane in human breath in real time avoiding sample storage. This method of analysis can ultimately form the basis of non-invasive screening of inflammatory processes, including inflammatory bowel disease.

Impaired Deoxyribonuclease I Activity in Patients with Inflammatory Bowel Diseases

Background and Aims. Deoxyribonuclease I (DNaseI) is an endonuclease that facilitates chromatin breakdown and promotes susceptibility to autoimmune disorders. The aim of current study was to investigate serum DNase I activity in patients with inflammatory bowel diseases (IBD). Patients and Methods. A cohort of 110 IBD patients was evaluated, aged 35 ± 12 years, 77 with Crohns disease (CD) and 33 with ulcerative colitis (UC). 50 SLE patients and 50 healthy blood donors were examined as control groups. Results. DNase I activity in IBD patients was significantly lower than in healthy individuals, but higher than in SLE patients (P < .0001). Patients with UC showed higher DNase I activity than CD patients, P = .21. DNase I activity in female patients with IBD was significantly lower than in males, P = .024; however, no differences in DNase I activity were found in relation to gender in healthy individuals. DNase I activity has shown a strong negative correlation with the serum concentration of anti-nucleosomal antibodies in the autoimmune (SLE + IBD) cohort, as well as in the separate IBD cohort. Conclusions. Reduced serum DNase I activity probably has pathogenetic consequences in IBD. Induction of autoantibodies towards nucleosomes could be a reflection of impaired DNase I activity.

Infliximab Biosimilar (Remsima™) in Therapy of Inflammatory Bowel Diseases Patients: Experience from One Tertiary Inflammatory Bowel Diseases Centre.

Background: The evidence on the efficacy and safety of biosimilar infliximab (IFX) in patients with inflammatory bowel diseases (IBD) is sparse. Methods: Consecutive IBD patients visiting our centre were included. One cohort composed of prospectively followed patients who were switched from original to biosimilar IFX between January and March 2015. The second cohort included retrospectively assessed anti-tumor necrosis factor α-naïve patients who started therapy between January 2015 and January 2016. Disease activity was assessed using standard clinical indices, endoscopic evaluation, and laboratory parameters (blood count, C-reactive protein (CRP) and fecal calprotectin (FC)). Trough levels and anti-drug antibodies (ATIs) were also measured. Patients were evaluated 56 weeks (W56) after switch and at week 14 (W14) and week 46 (W46) in the naïve cohort. Results: Seventy-four IBD patients were switched to biosimilar IFX and 119 naïve patients newly initiated therapy with the preparation. Disease activity remained stable in a majority of switched patients (remission at week 0 (W0) vs. W56: 72.2 vs. 77.8%; median difference of both Harvey-Bradshaw index and Simple Clinical Colitis Activity Index between W0 and W56 was 0). When W0 and W56 were compared, no significant difference in CRP (4.3 ± 8.0 vs. 3.3 ± 3.8 mg/l; p = 0.89) and FC (135 ± 153 vs. 199 ± 225 µg/g; p = 0.17) was observed. In total, 92% of Crohns disease (CD) and 83% of ulcerative colitis (UC) patients responded to induction therapy (W14) with biosimilar IFX. At W46, the response rate was 86% in CD and 64% in UC. Moreover, half of UC patients experienced mucosal healing at W14 and improvement of perianal disease occurred in 95% of CD at W46. In this cohort, clear steroid-sparing effect was observed. No increase in immunogenicity was found in switched patients (ATI positivity: 9.5 vs. 6.0%, p = 0.54) and the type and frequency of adverse events were comparable to the original preparation in both cohorts. Conclusion: Switching of IBD patients from original to biosimilar IFX is effective and safe.

Pentane and other volatile organic compounds, including carboxylic acids, in the exhaled breath of patients with Crohn’s disease and ulcerative colitis

A study has been carried out on the volatile organic compounds (VOCs) in the exhaled breath of patients suffering from inflammatory bowel disease (IBD), comprising 136 with Crohns disease (CD) and 51 with ulcerative colitis (UC), together with a cohort of 14 healthy persons as controls. Breath samples were collected by requesting the patients to inflate Nalophan bags, which were then quantitatively analysed using selected ion flow tube mass spectrometry (SIFT-MS). Initially, the focus was on n-pentane that had previously been quantified in single exhalations on-line to SIFT-MS for smaller cohorts of IBD patients. It was seen that the median concentration of pentane was elevated in the bag breath samples of the IBD patients compared to those of the healthy controls, in accordance with the previous study. However, the absolute median pentane concentrations in the bag samples were about a factor of two lower than those in the directly analysed single exhalations-a good illustration of the dilution of VOCs in the samples of breath collected into bags. Accounting for this dilution effect, the concentrations of the common breath VOCs, ethanol, propanol, acetone and isoprene, were largely as expected for healthy controls. The concentrations of the much less frequently measured hydrogen sulphide, acetic acid, propanoic acid and butanoic acid were seen to be more widely spread in the exhaled breath of the IBD patients compared to those for the healthy controls. The relative concentrations of pentane and these other VOCs weakly correlate with simple clinical activity indices. It is speculated that, potentially, hydrogen sulphide and these carboxylic acids could be exhaled breath biomarkers of intestinal bacterial overgrowth, which could assist therapeutic intervention and thus alleviate the symptoms of IBD.