Evaluation of lipid peroxidation by the analysis of volatile aldehydes in the headspace of synthetic membranes using Selected Ion Flow Tube Mass Spectrometry, SIFT-MS

Anti-ulcerative effects of wogonin on ulcerative colitis induced by dextran sulfate sodium via Nrf2/TLR4/NF-κB signaling pathway in BALB/c mice

Ulcerative colitis (UC) is an inflammatory disease on the deepest lining of the colon and rectum. Wogonin is an antitumor flavonoid, which possesses various therapeutic properties. Even if the anti-colitis effect of wogonin was documented earlier, but the wogonin effect on inflammation underlying mechanism is not fully elucidated. In this present study, we hypothesized to study the oxidative damage, anti-inflammatory, and molecular action of wogonin on dextran sulfate sodium (DSS)-induced UC mice model. In methods, mice were categorized into four groups: that is, normal control, DSS alone, DSS + wogonin (30 mg/kg/day), and DSS + sulfasalazine (50 mg/kg/day). We determined the biochemical markers, inflammatory cytokines, histopathology of colon tissue, and western blot analysis. DSS significantly reduced body weight, colon length, and increased inflammation in the colon. Wogonin treatment prevented colonic ulceration, neutrophil infiltration, oxidative stress, pro-inflammatory cytokines, and histological changes. Oxidative damage and inflammatory mediators' elevation were also dramatically diminished by wogonin. Wogonin activates apoptosis via inhibiting Bcl-2 and augmenting Bax, caspase-3, and -9 expressions. Wogonin downregulated the COX-2 and iNOS, thereby repressing NF-κB. Wogonin regulated the Nrf2 signaling pathway and decreased TLR-4/NF-κB triggering. Taken together our study exposed that wogonin has a promising anti-ulcerative agent and recommended for good anti-inflammatory drug in the colon.

Volutrauma Increases Exhaled Pentanal in Rats: A Potential Breath Biomarker for Ventilator-Induced Lung Injury

BACKGROUND

Mechanical ventilation injures lungs, but there are currently no reliable methods for detecting early injury. We therefore evaluated whether exhaled pentanal, a lipid peroxidation product, might be a useful breath biomarker for stretch-induced lung injury in rats.

METHODS

A total of 150 male Sprague-Dawley rats were investigated in 2 substudies. The first randomly assigned 75 rats to 7 hours of mechanical ventilation at tidal volumes of 6, 8, 12, 16, and 20 mL·kg-1. The second included 75 rats. A reference group was ventilated at a tidal volume of 6 mL·kg-1 for 10 hours 4 interventional groups were ventilated at a tidal volume of 6 mL·kg-1 for 1 hour, and then for 0.5, 1, 2, or 3 hours at a tidal volume of 16 mL.kg-1 before returning to a tidal volume of 6 mL·kg-1 for additional 6 hours. Exhaled pentanal was monitored by multicapillary column-ion mobility spectrometry. The first substudy included cytokine and leukocyte measurements in blood and bronchoalveolar fluid, histological assessment of the proportion of alveolar space, and measurements of myeloperoxidase activity in lung tissue. The second substudy included measurements of pentanal in arterial blood plasma, cytokine and leukocyte concentrations in bronchoalveolar fluid, and cleaved caspase 3 in lung tissue.

RESULTS

Exhaled pentanal concentrations increased by only 0.5 ppb·h-1 (95% confidence interval [CI], 0.3-0.6) when rats were ventilated at 6 mL·kg-1. In contrast, exhaled pentanal concentrations increased substantially and roughly linearly at higher tidal volumes, up to 3.1 ppb·h-1 (95% CI, 2.3-3.8) at tidal volumes of 20 mL·kg-1. Exhaled pentanal increased at average rates between 1.0 ppb·h-1 (95% CI, 0.3-1.7) and 2.5 ppb·h-1 (95% CI, 1.4-3.6) after the onset of 16 mL·kg-1 tidal volumes and decreased rapidly by a median of 2 ppb (interquartile range [IQR], 0.9-3.2), corresponding to a 38% (IQR, 31-43) reduction when tidal volume returned to 6 mL·kg-1. Tidal volume, inspiratory pressure, and mechanical power were positively associated with pentanal exhalation. Exhaled and plasma pentanal were uncorrelated. Alveolar space decreased and inflammatory markers in bronchoalveolar lavage fluid increased in animals ventilated at high tidal volumes. Short, intermittent ventilation at high tidal volumes for up to 3 hours increased neither inflammatory markers in bronchoalveolar fluid nor the proportion of cleaved caspase 3 in lung tissue.

CONCLUSIONS

Exhaled pentanal is a potential biomarker for early detection of ventilator-induced lung injury in rats.

Quantification of Volatile Aldehydes Deriving from In Vitro Lipid Peroxidation in the Breath of Ventilated Patients

Exhaled aliphatic aldehydes were proposed as non-invasive biomarkers to detect increased lipid peroxidation in various diseases. As a prelude to clinical application of the multicapillary column–ion mobility spectrometry for the evaluation of aldehyde exhalation, we, therefore: (1) identified the most abundant volatile aliphatic aldehydes originating from in vitro oxidation of various polyunsaturated fatty acids; (2) evaluated emittance of aldehydes from plastic parts of the breathing circuit; (3) conducted a pilot study for in vivo quantification of exhaled aldehydes in mechanically ventilated patients. Pentanal, hexanal, heptanal, and nonanal were quantifiable in the headspace of oxidizing polyunsaturated fatty acids, with pentanal and hexanal predominating. Plastic parts of the breathing circuit emitted hexanal, octanal, nonanal, and decanal, whereby nonanal and decanal were ubiquitous and pentanal or heptanal not being detected. Only pentanal was quantifiable in breath of mechanically ventilated surgical patients with a mean exhaled concentration of 13 ± 5 ppb. An explorative analysis suggested that pentanal exhalation is associated with mechanical power—a measure for the invasiveness of mechanical ventilation. In conclusion, exhaled pentanal is a promising non-invasive biomarker for lipid peroxidation inducing pathologies, and should be evaluated in future clinical studies, particularly for detection of lung injury.

Differential Response of Pentanal and Hexanal Exhalation to Supplemental Oxygen and Mechanical Ventilation in Rats

High inspired oxygen during mechanical ventilation may influence the exhalation of the previously proposed breath biomarkers pentanal and hexanal, and additionally induce systemic inflammation. We therefore investigated the effect of various concentrations of inspired oxygen on pentanal and hexanal exhalation and serum interleukin concentrations in 30 Sprague Dawley rats mechanically ventilated with 30, 60, or 93% inspired oxygen for 12 h. Pentanal exhalation did not differ as a function of inspired oxygen but increased by an average of 0.4 (95%CI: 0.3; 0.5) ppb per hour, with concentrations doubling from 3.8 (IQR: 2.8; 5.1) ppb at baseline to 7.3 (IQR: 5.0; 10.8) ppb after 12 h. Hexanal exhalation was slightly higher at 93% of inspired oxygen with an average difference of 0.09 (95%CI: 0.002; 0.172) ppb compared to 30%. Serum IL-6 did not differ by inspired oxygen, whereas IL-10 at 60% and 93% of inspired oxygen was greater than with 30%. Both interleukins increased over 12 h of mechanical ventilation at all oxygen concentrations. Mechanical ventilation at high inspired oxygen promotes pulmonary lipid peroxidation and systemic inflammation. However, the response of pentanal and hexanal exhalation varies, with pentanal increasing by mechanical ventilation, whereas hexanal increases by high inspired oxygen concentrations.

A review of breath analysis techniques in head and neck cancer

Cancers of the head and neck region are a severely disabling group of diseases with no method for early detection. Analysis of exhaled breath volatile organic compounds shows promise as biomarkers for early detection and disease monitoring. This article reviews breath analysis in the setting of head and neck cancer, with a practical focus on breath sampling techniques, detection technologies and valid data analysis methods. Title and abstract keyword searches were conducted on PubMed and Embase databases to identify English language studies without a time-period limitation. The main inclusion criteria were human studies comparing head and neck cancer patients to healthy controls using exhaled breath analysis. Multiple breath collection techniques, three major detection technologies and multiple data analysis methods were identified. However, the variability in techniques and lack of methodological standardization does not allow for adequate study replication or data pooling. Twenty-two volatile organic compounds identified in five studies have been reported to discriminate head and neck cancer patients from healthy controls. Breath analysis for detection of head and neck cancer shows promise as a non-invasive detection tool. However, methodological standardization is paramount for future research study design to provide the potential for translating these techniques into routine clinical use.

Comparative metabolic expressions of fermented soybeans according to different microbial starters

The quality of fermented soybeans can be determined by diverse metabolites produced by microorganisms. Mass spectrometry-based metabolomic approach was applied to investigate the differences in volatile and non-volatile metabolite profiles of fermented soybeans by different microorganisms [e.g., molds, yeasts, lactic acid bacteria (LAB), and other bacteria]. The partial least squares-discriminant analysis (PLS-DA) for volatile metabolites profiles indicated that the fungi group (mold/yeast) was clearly discriminated from the bacteria group (bacteria/LAB). The metabolic pathways related to the formation of volatile metabolites also differed according to microorganisms. In particular, the formation of branched-chain aliphatic alcohols and esters increased in the fungi group, while that of volatiles derived from fatty acids was superior in the bacteria group. In addition, we could determine the microorganism-specific metabolites using a correlation network analysis. This study can provide the fundamental knowledge on the metabolic differences according to the type of microorganisms in fermented soybeans.

Direct analysis of aldehydes and carboxylic acids in the gas phase by negative ionization selected ion flow tube mass spectrometry: Quantification and modelling of ion-molecule reactions

RATIONALE

The concentrations of aldehydes and volatile fatty acids have to be controlled because of their potential harmfulness in indoor air or relationship with the organoleptic properties of agri-food products. Although several specific analytical methods are currently used, the simultaneous analysis of these compounds in a complex matrix remains a challenge. The combination of positive and negative ionization selected ion flow tube mass spectrometry (SIFT-MS) allows the accurate, sensitive and high-frequency analysis of complex gas mixtures of these compounds.

METHODS

The ion-molecule reactions of negative precursor ions (OH^- , O^•- , O₂ ^•- , NO₂ ^- and NO₃ ^- ) with five aldehydes and four carboxylic acids were investigated in order to provide product ions and rate constants for the quantification of these compounds by negative ion SIFT-MS. The results were compared with those obtained by conventional analysis methods and/or with already implemented SIFT-MS positive ionization methods. The modelling of hydroxide ion (OH^- )/molecule reaction paths by ab-initio calculation allowed a better understanding of these gas-phase reactions.

RESULTS

Deprotonation systematically occurs by reaction between negative ions and aldehydes or acids, leading to the formation of [M - H]^- primary ions. Ab-initio calculations demonstrated the α-CH deprotonation of aldehydes and the acidic proton abstraction for fatty acids. For aldehydes, the presence of water in the flow tube leads to the formation of hydrated ions, [M - H]^- .H₂ O. With the NO₂ ^- precursor ion, a second reaction channel results in ion-molecule association with the formation of M.NO₂ ^- ions.

CONCLUSIONS

Except for formaldehyde, all the studied compounds can be quantified by negative ion SIFT-MS with significant rate constants. In addition to positive ion SIFT-MS with H₃ O⁺ , O₂ ⁺ and NO⁺ precursor ions, negative ionization with O^•- , O₂ ^•- , OH^- , NO₂ ^- and NO₃ ^- extends the range of analysis of aldehydes and carboxylic acids in air without a preparation or separation step. This methodology was illustrated by the simultaneous quantification in single-scan experiments of seven aldehydes and six carboxylic acids released by building materials.

Modeling cellular metabolomic effects of oxidative stress impacts from hydrogen peroxide and cigarette smoke on human lung epithelial cells

The respiratory system is continuously exposed to variety of biological and chemical irritants that contain reactive oxygen species, and these are well known to cause oxidative stress responses in lung epithelial cells. There is a clinical need to identify biomarkers of oxidative stress which could potentially support early indicators of disease and health management. To identify volatile biomarkers of oxidative stress, we analyzed the headspace above human bronchial epithelial cell cultures (HBE1) before and after hydrogen peroxide (H₂O₂) and cigarette smoke extract (CSE) exposure. Using stir bar and headspace sorptive extraction-gas chromatography-mass spectrometry, we searched for volatile organic compounds (VOC) of these oxidative measures. In the H₂O₂ cell peroxidation experiments, four different H₂O₂ concentrations (0.1, 0.5, 10, 50 mM) were applied to the HBE1 cells, and VOCs were collected every 12 h over the time course of 48 h. In the CSE cell peroxidation experiments, four different smoke extract concentrations (0%, 10%, 30%, 60%) were applied to the cells, and VOCs were collected every 12 h over the time course of 48 h. We used partial-least squares (PLS) analysis to identify putative compounds from the mass spectrometry results that highly correlated with the known applied oxidative stress. We observed chemical emissions from the cells that related to both the intensity of the oxidative stress and followed distinct time courses. Additionally, some of these chemicals are aldehydes, which are thought to be non-invasive indicators of oxidative stress in exhaled human breath. Together, these results illustrate a powerful in situ cell culture model of oxidative stress that can be used to explore the putative biological genesis of exhaled breath biomarkers that are often observed in human clinical studies.

Dynamic headspace analysis using online measurements: Modeling of average and initial concentration

Dynamic headspace sampling is an important technique for the analysis of consumer products, the study of biological samples and environmental water analyses. This paper shows the influence of experimental conditions, such as the sampling time, sampling flow rate, headspace volume, liquid volume and Henry coefficient on the measured average concentration values. A corresponding closed expression as function of these variables is introduced in order to quantify the deviation of the initial headspace concentration. The proposed bi-exponential function embeds different current existing models for recovery calculation in dynamic sampling analyses in one single expression. A fully automated and user-friendly Excel^® file to investigate or to model the dynamic headspace sampling results is added to everyone's easy use.