Breath Acetaldehyde Research Articles

Rapid screen for ventilator associated pneumonia using exhaled volatile organic compounds

Ventilator associated pneumonia (VAP) is an infectious disease with high incidence rate and mortality in intensive care unit (ICU). The traditional etiological diagnosis method usually takes more than 24 h, delaying the treatment time and resulting in a mortality rate of up to 10%. In this study, we tried to achieve the rapid screening of VAP using exhaled volatile organic compounds (VOCs). The breath samples of 42 patients with VAP and 32 uninfected people from ICU were collected through intubation sampling and detected using a proton transfer reaction-mass spectrometry (PTR-MS). The collection and detection process only took less than 10 min. And then, Mann Whitney U test and stepwise discriminant analysis were used to discover the characteristic ions of VAP, which can be used to discriminate the two groups. Finally, we cultured five major pathogens (P. aeruginosa, K. pneumoniae, A. baumannii, E. coli and S. maltophilia) from VAP patients. The relationships between exhaled VOCs from the infected patients and VOCs released by the five pathogens were analyzed. The results showed that exhaled acetaldehyde could be used alone for screening VAP. The sensitivity and specificity were 71.4% and 84.4%, respectively, and the area under the curve (AUC) obtained by receiver operating characteristics (ROC) analysis was 0.796. We also found a large amount of acetaldehyde was produced by the five pathogens in the process of proliferation. Moreover, the content of exhaled acetaldehyde was positively correlated with the number of pathogens. So, we speculated the VAP biomarker acetaldehyde in the exhaled breath was mainly originated from these pathogens. In conclusion, the rapid screening of VAP can be achieved through detection of exhaled acetaldehyde using PTR-MS, which can assist doctors making treatment strategies in time.

Breath octane and acetaldehyde as markers for acute respiratory distress syndrome in invasively ventilated patients suspected to have ventilator-associated pneumonia.

RationaleThe concentration of octane and acetaldehyde in exhaled breath has good diagnostic accuracy for acute respiratory distress syndrome (ARDS). We aimed to determine whether breath octane and acetaldehyde are able to distinguish the presence and absence of ARDS in critically ill patients suspected to have ventilator-associated pneumonia (VAP).MethodsThis is a secondary analysis of a prospective observational study into exhaled breath analysis using gas chromatography–time-of-flight mass spectrometry. Difference in the relative abundance of octane and acetaldehyde in exhaled breath was compared between patients with and without ARDS using the Mann–Whitney U-test and the association was quantified using logistic regression. The discriminative accuracy of octane and acetaldehyde, alone or in combination, was calculated using the area under the receiver operating characteristic curve (AUROCC).ResultsWe included 98 patients, of whom 32 had ARDS and 66 did not. The area under the acetaldehyde peak was higher in patients with ARDS (p=0.03), and associated with the presence of ARDS (OR 1.06 per 100 000 count change, 95% CI 1.02–1.13 per 100 000 count change; p=0.01). A combined model with octane and acetaldehyde showed a high specificity and low sensitivity (90% and 40.6%, respectively), with a low accuracy (AUROCC 0.65, 95% CI 0.53–0.78).ConclusionPatients suspected to have VAP with ARDS had a higher acetaldehyde concentration in exhaled breath than patients suspected to have VAP without ARDS. However, in this patient population, discrimination of these breath biomarkers for ARDS was poor, indicating the difficulty of translating diagnostic tests between clinical settings.

(Invited) Bio-Sniffers & Sniff-Cam: Biofluorometirc Gas Sensor and Imaging System for Human Volatile Chemicals

Introduction Various volatile organic compounds exist, such as those the transpired by humans, breath, body odor and smell of the living environment. The human body emits various volatile molecules, depending on a person’s genetics, disease and metabolic condition. In this contribution, novel gas-phase biosensors (bio-sniffer and sniff-cam) using bio-fluorometric techniques for human volatiles will be introduced as a future biosensing approach for preemptive medicine and healthcare. Bio-sniffer for breath acetone as early screening approach of diabetes mellitus. Secondary alcohol dehydrogenase (S-ADH) catalyzes the reduction of acetone and the oxidation of nicotinamide adenine dinucleotide (NADH to NAD+) in a weak acid environment (Fig.1). NADH is excited by 340 nm excitation lights and subsequently emit 490 nm fluorescence. Therefore, acetone can be measured by the decrease in NADH fluorescence intensity. A bio-fluorometric acetone sniffer was constructed by incorporating an optic-probe into a gas/liquid flow cell with S-ADH immobilized diaphragm (Fig.2) [1,2]. The developed biosniffer show rapid response, highly sensitivity and selectivity to acetone. The breath acetone analysis in healthy subjects shows that the mean values were 750.0 ± 434.4 ppb. The breath acetone did not show a statistical difference among different genders and ages. The breath acetone analysis for diabetic patients under medical treatment shows a mean value of 1207.7 ± 689.5 ppb, which was higher than that of healthy subjects (p < 1 × 10−6). In particularly, type-1 diabetic (T1D) patients exhaled a much higher concentration of acetone than type-2 diabetic (T2D) patients (p < 0.01) (Fig.3). These findings are worthwhile in the study of breath biomarkers for early screening of diabetes mellitus. Additionally, the developed bio-sniffers provide a new technique for volatolomics research. Sniff-cam with biofluorometric technique for spatiotemporal gas imaging A decade ago, a chemiluminescence sniff-cam system was developed and applied successfully for distribution imaging of high concentration ethanol vapor (ppm-level) such as breath ethanol after drinking (Fig.4) [3] and wine aroma from wine glass (Fig.5) [4]. In order to improve the performance, we applied the bio-fluorometric technique for highly sensitive sniff-cam system (ppb-level). The sniff-cam with ADH (alcohol dehydrogenase) redox reactions can show a spatiotemporal change of gaseous ethanol (EtOH) or acetaldehyde (AcH) in real-time [5,6]. The sniff-cam was composed of a highly sensitive camera, a UV-LED array sheet, and an ADH-immobilized mesh. The both redox reactions of ADH were employed for detection of gaseous EtOH and AcH where a relationship between fluorescence intensity from nicotinamide adenine dinucleotide. Moreover, the image differentiation method that calculated a fluorescence change rate was employed to visualize a real-time change in the concentration distribution of EtOH and AcH. The dynamic ranges of the sniff-cam for EtOH and AcH were 20ppb-300ppm and 100 ppb-10 ppm. As the physiological application, the sniff-cam successfully achieved the imaging of the concentration distribution of EtOH and AcH in breath and skin gas (Fig. 6). Future potential of the gas-phase biosensors (bio-sniffer and sniff-cam) The future potential of the bio-sniffer and sniff-cam for body volatiles includes the early disease screening, the identification of those locations, the real time evaluation of metabolic condition as a Bio-IoT monitoring.

(Invited) Bio-Sniffers & Sniff-Cam: Biofluorometirc Gas Sensor and Imaging System for Human Volatile Chemicals

Introduction Various volatile organic compounds exist, such as those the transpired by humans, breath, body odor and smell of the living environment. The human body emits various volatile molecules, depending on a person’s genetics, disease and metabolic condition. In this contribution, novel gas-phase biosensors (bio-sniffer and sniff-cam) using bio-fluorometric techniques for human volatiles will be introduced as a future biosensing approach for preemptive medicine and healthcare. Bio-sniffer for breath acetone as early screening approach of diabetes mellitus. Secondary alcohol dehydrogenase (S-ADH) catalyzes the reduction of acetone and the oxidation of nicotinamide adenine dinucleotide (NADH to NAD+) in a weak acid environment (Fig.1). NADH is excited by 340 nm excitation lights and subsequently emit 490 nm fluorescence. Therefore, acetone can be measured by the decrease in NADH fluorescence intensity. A bio-fluorometric acetone sniffer was constructed by incorporating an optic-probe into a gas/liquid flow cell with S-ADH immobilized diaphragm (Fig.2) [1,2]. The developed biosniffer show rapid response, highly sensitivity and selectivity to acetone. The breath acetone analysis in healthy subjects shows that the mean values were 750.0 ± 434.4 ppb. The breath acetone did not show a statistical difference among different genders and ages. The breath acetone analysis for diabetic patients under medical treatment shows a mean value of 1207.7 ± 689.5 ppb, which was higher than that of healthy subjects (p < 1 × 10−6). In particularly, type-1 diabetic (T1D) patients exhaled a much higher concentration of acetone than type-2 diabetic (T2D) patients (p < 0.01) (Fig.3). These findings are worthwhile in the study of breath biomarkers for early screening of diabetes mellitus. Additionally, the developed bio-sniffers provide a new technique for volatolomics research. Sniff-cam with biofluorometric technique for spatiotemporal gas imaging A decade ago, a chemiluminescence sniff-cam system was developed and applied successfully for distribution imaging of high concentration ethanol vapor (ppm-level) such as breath ethanol after drinking (Fig.4) [3] and wine aroma from wine glass (Fig.5) [4]. In order to improve the performance, we applied the bio-fluorometric technique for highly sensitive sniff-cam system (ppb-level). The sniff-cam with ADH (alcohol dehydrogenase) redox reactions can show a spatiotemporal change of gaseous ethanol (EtOH) or acetaldehyde (AcH) in real-time [5,6]. The sniff-cam was composed of a highly sensitive camera, a UV-LED array sheet, and an ADH-immobilized mesh. The both redox reactions of ADH were employed for detection of gaseous EtOH and AcH where a relationship between fluorescence intensity from nicotinamide adenine dinucleotide. Moreover, the image differentiation method that calculated a fluorescence change rate was employed to visualize a real-time change in the concentration distribution of EtOH and AcH. The dynamic ranges of the sniff-cam for EtOH and AcH were 20ppb-300ppm and 100 ppb-10 ppm. As the physiological application, the sniff-cam successfully achieved the imaging of the concentration distribution of EtOH and AcH in breath and skin gas (Fig. 6). Future potential of the gas-phase biosensors (bio-sniffer and sniff-cam) The future potential of the bio-sniffer and sniff-cam for body volatiles includes the early disease screening, the identification of those locations, the real time evaluation of metabolic condition as a Bio-IoT monitoring.

Protective effects of Alda-1, an ALDH2 activator, on alcohol-derived DNA damage in the esophagus of human ALDH2*2 (Glu504Lys) knock-in mice.

Alcohol consumption is the key risk factor for the development of esophageal squamous cell carcinoma (ESCC), and acetaldehyde, a metabolite of alcohol, is an alcohol-derived major carcinogen that causes DNA damage. Aldehyde dehydrogenase2 (ALDH2) is an enzyme that detoxifies acetaldehyde, and its activity is reduced by ALDH2 gene polymorphism. Reduction in ALDH2 activity increases blood, salivary and breath acetaldehyde levels after alcohol intake, and it is deeply associated with the development of ESCC. Heavy alcohol consumption in individuals with ALDH2 gene polymorphism significantly elevates the risk of ESCC; however, effective prevention has not been established yet. In this study, we investigated the protective effects of Alda-1, a small molecule ALDH2 activator, on alcohol-mediated esophageal DNA damage. Here, we generated novel genetically engineered knock-in mice that express the human ALDH2*1 (wild-type allele) or ALDH2*2 gene (mutant allele). Those mice were crossed, and human ALDH2*1/*1, ALDH2*1/*2 and ALDH2*2/*2 knock-in mice were established. They were given 10% ethanol for 7 days in the presence or absence of Alda-1, and we measured the levels of esophageal DNA damage, represented by DNA adduct (N2-ethylidene-2′-deoxyguanosine). Alda-1 significantly increased hepatic ALDH2 activity both in human ALDH2*1/*2 and/or ALDH2*2/*2 knock-in mice and reduced esophageal DNA damage levels after alcohol drinking. Conversely, cyanamide, an ALDH2-inhibitor, significantly exacerbated esophageal DNA adduct level in C57BL/6N mice induced by alcohol drinking. These results indicate the protective effects of ALDH2 activation by Alda-1 on esophageal DNA damage levels in individuals with ALDH2 gene polymorphism, providing a new insight into acetaldehyde-mediated esophageal carcinogenesis and prevention.

Switchable sniff-cam (gas-imaging system) based on redox reactions of alcohol dehydrogenase for ethanol and acetaldehyde in exhaled breath

Measuring the volatile organic compounds (VOCs) released from a human is a promising method for noninvasive disease screening and metabolism assessment. Selectively imaging multiple VOCs derived from human breath and skin gas is expected to improve current gas analysis techniques. In this study, a gas-imaging system (sniff-cam) that can be used to simultaneously image the concentration distribution of multiple VOCs, namely, ethanol (EtOH) and acetaldehyde (AcH), was developed. The sniff-cam was based on the pH-dependent redox reactions of nicotinamide adenine dinucleotide (NAD)-dependent alcohol dehydrogenase (ADH). The sniff-cam was constructed with a camera, two ADH-immobilized meshes, and a UV-LED array sheet. The ADH-immobilized mesh containing a solution of the oxidized form of NAD (NAD+) or reduced form (NADH) was used as an EtOH-imaging mesh and an AcH-imaging mesh, respectively. The distributions of the EtOH and AcH concentrations were visualized through the fluorescence of NADH (the excitation wavelength was 340 nm; the emission wavelength was 490 nm) occurring by the ADH-mediated redox reaction. First, the influence of pH on the activity of the redox reaction of ADH was measured, and then the quantitativeness and selectivity of the sniff-cam were evaluated. The ADH-mediated reactions of EtOH and AcH showed maximum activities at pH 9.0 and pH 6.5, respectively. The sniff-cam demonstrated not only a dynamic range (0.1–1000 ppm for EtOH and 0.2–10 ppm for AcH) for measuring EtOH and AcH in breath after drinking alcohol, but also displayed a high selectivity against other breath VOCs. Finally, EtOH and AcH in breath after drinking alcohol were measured simultaneously. A group with high activity of aldehyde dehydrogenase type 2 (EtOH = 143.3 ± 13.5 ppm, AcH = 1.7 ± 0.2 ppm) and a group with low activity (EtOH = 163.3 ± 28.0 ppm, AcH = 8.4 ± 0.5 ppm) displayed differences in the concentrations of EtOH and AcH contained in their breath samples, and the effectiveness of the developed method was confirmed and compared with previous results. It is suggested that the multiplexed sniff-cam in the future may be capable of selectively and simultaneously imaging various VOCs in human breath and skin gas by using multiple NADH-dependent enzymes.

Effect of Alcohol Sensitivity in Healthy Young Adults on Breath Pharmacokinetics of Acetaldehyde After Mouth Washing with Alcohol.

Acetaldehyde is causally related to head and neck cancer. Individuals with aldehyde dehydrogenase 2 deficiency experience alcohol sensitivity and are referred to as "flushers" because of their skin-flushing response to high blood acetaldehyde levels after alcohol consumption. Acetaldehyde is produced in the oral cavity after local alcohol exposure without alcohol ingestion. However, the relationship between the oral acetaldehyde level after local alcohol exposure and alcohol sensitivity is unclear. Herein, sampling the exhaled breath, we evaluated the effect of alcohol sensitivity on the pharmacokinetics of ethanol (EtOH) and acetaldehyde in breath after mouth washing with alcohol. Twenty-eight healthy young adults were divided into flusher and nonflusher groups based on an EtOH patch test. The subjects washed their mouths for 30seconds with 40ml of 5% v/v alcohol, and their breath samples were collected 12 times over 20minutes after mouth washing and rinsing with water. EtOH and acetaldehyde concentrations in all breath samples were measured using sensor gas chromatography. Breath EtOH concentrations exponentially decreased in both groups after mouth washing with alcohol. Breath acetaldehyde concentrations showed an immediate increase, followed by an almost exponential decrease in both groups, but concentrations in the flusher group remained higher than those in the nonflusher group throughout the 20-minute measurement period. This was reflected in a peak concentration (Cmax ) of 808±70parts-per-billion (ppb) versus 1,715±223ppb, respectively (p=0.001), and area under the curve values of 3,528±1,399ppb minutes versus 8,637±1,293ppb minutes, respectively (p=0.002). This study revealed high concentrations of acetaldehyde in breath after local alcohol exposure in the oral cavity among flushers even without alcohol ingestion. This contributes to an increased risk among flushers of mutagenic DNA lesions in the mucosa of the upper digestive tract and cancer.

Fluorometric Sniff-Cam (Gas-Imaging System) Utilizing Alcohol Dehydrogenase for Imaging Concentration Distribution of Acetaldehyde in Breath and Transdermal Vapor after Drinking.

Understanding concentration distributions, release sites, and release dynamics of volatile organic compounds (VOCs) from the human is expected to lead to methods for noninvasive disease screening and assessment of metabolisms. In this study, we developed a visualization system (sniff-cam) that enabled one to identify a spatiotemporal change of gaseous acetaldehyde (AcH) in real-time. AcH sniff-cam was composed of a camera, a UV-LED array sheet, and an alcohol dehydrogenase (ADH)-immobilized mesh. A reverse reaction of ADH was employed for detection of gaseous AcH where a relationship between fluorescence intensity from nicotinamide adenine dinucleotide and the concentration of AcH was inversely proportional; thus, the concentration distribution of AcH was measured by detecting the fluorescence decrease. Moreover, the image differentiation method that calculated a fluorescence change rate was employed to visualize a real-time change in the concentration distribution of AcH. The dynamic range of the sniff-cam was 0.1-10 ppm which encompassed breath AcH concentrations after drinking. Finally, the sniff-cam achieved the visualization of the concentration distribution of AcH in breath and skin gas. A clear difference of breath AcH concentration was observed between aldehyde dehydrogenase type 2 active and inactive subjects, which was attributed to metabolic capacities of AcH. AcH in skin gas showed a similar time course of AcH concentration to the breath and a variety of release concentration distribution. Using different NADH-dependent dehydrogenases in the sniff-cam could lead to a versatile method for noninvasive disease screening by acquiring spatiotemporal information on various VOCs in breath or skin gas.

Establishment of a Quick and Highly Accurate Breath Test for ALDH2 Genotyping.

Objectives:Acetaldehyde, the first metabolite of ethanol, is a definite carcinogen for the esophagus, head, and neck; and aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme that catalyzes the metabolism of acetaldehyde. The ALDH2 genotype exists as ALDH2*1/*1 (active ALDH2), ALDH2*1/*2 (heterozygous inactive ALDH2), and ALDH2*2/*2 (homozygous inactive ALDH2). Many epidemiological studies have reported that ALDH2*2 carriers are at high risk for esophageal or head and neck squamous cell carcinomas by habitual drinking. Therefore, identification of ALDH2*2 carriers would be helpful for the prevention of those cancers, but there have been no methods suitable for mass screening to identify these individuals.Methods:One hundred and eleven healthy volunteers (ALDH2*1/*1 carriers: 53; ALDH2*1/*2 carriers: 48; and ALDH2*2/*2 carriers: 10) were recruited. Breath samples were collected after drinking 100 ml of 0.5% ethanol using specially designed gas bags, and breath ethanol and acetaldehyde levels were measured by semiconductor gas chromatography.Results:The median (range) breath acetaldehyde levels at 1 min after alcohol ingestion were 96.1 (18.1–399.0) parts per billion (p.p.b.) for the ALDH2*1/*1 genotype, 333.5 (78.4–1218.4) p.p.b. for the ALDH2*1/*2 genotype, and 537.1 (213.2–1353.8) p.p.b. for the ALDH2*2/*2 genotype. The breath acetaldehyde levels in ALDH2*2 carriers were significantly higher than for the ALDH2*1/*1 genotype. Notably, the ratio of breath acetaldehyde level-to-breath ethanol level could identify carriers of the ALDH2*2 allele very accurately (whole accuracy; 96.4%).Conclusions:Our novel breath test is a useful tool for identifying ALDH2*2 carriers, who are at high risk for esophageal and head and neck cancers.

Sniff-Cam (Bio-Fluorometric Gas-Imaging System) for Breath Acetaldehyde after Drinking

We developed Sniff-cam (bio-fluorometric gas-imaging system) for visualization of breath acetaldehyde (ACE) which is produced by ethanol metabolism in liver after drinking. Sniff-cam employed an alcohol dehydrogenase (ADH) immobilized cotton mesh with reduced nicotinamide adenine dinucleotide (NADH) for imaging of gaseous ACE distribution. NADH is consumed by ADH-mediated reduction of ACE, and its concentration and that of ACE are correlated. Therefore, imaging of gaseous ACE distribution was achieved by exciting NADH with an ultraviolet light-emitting diode array (340 nm wavelength) and recording the emitted fluorescence from NADH (490 nm wavelength) by a high sensitive camera. Decrement of fluorescence at around the gas outlet was observed when ACE vapor was introduced. This result demonstrates that the Sniff-cam could be applied for imaging of breath ACE.

Acetaldehyde/ethanol breath test for identifying people at high risk of upper aerodigestive tract cancer.

18 Background: Alcohol drinking increases the risk of upper aerodigestive tract cancer, and acetaldehyde (a metabolite of alcohol) is a definite carcinogen for this type of cancer. Acetaldehyde is formed mainly by the oxidation of ethanol by alcohol dehydrogenase 1B (ADH1B) and is eliminated by aldehyde dehydrogenase 2 (ALDH2) in the liver. About 50% of Asian people have the ALDH2*2 variant allele, which encodes an inactive enzyme. Those with the ALDH2*2 allele and an alcohol drinking habit are at definite risk of esophageal and head and neck cancers. Genetic testing is the most reliable method for identifying the ALDH2 genotype, but it is not practical for mass screening because of the cost and time. Therefore, we have established a simple method to identify the ALDH2 genotype by analyzing breath samples. Methods: One hundred seven consecutive healthy Japanese volunteers participated in this study. After providing informed consent, participants drank 100 ml of 0.5% ethanol in a single gulp. Breath samples were collected with originally developed simple gasbags before the alcohol was consumed, and 1, 2, and 5 minutes later. The concentrations of acetaldehyde and ethanol in the bag were measured by high-sensitivity gas chromatography. The ALDH2 and ADH1B genotypes of all participants were confirmed using blood DNA. The relationships between acetaldehyde level and genotypes were determined. Results: The frequencies of ALDH2*1/*1, ALDH2*1/*2, and ALDH2*2/*2 were 46.7%, 43.9%, and 9.3%, respectively. The breath acetaldehyde levels at 1 minute after alcohol ingestion were 89.2 (18.1–399.0) ppb in those with ALDH2*1/*1, 346.3 (78.4–1218.4) ppb in those with ALDH2*1/*2, and 537.1 (213.2–1353.8) ppb in those with ALDH2*2/*2. The breath acetaldehyde level was significantly higher in the ALDH2*2 carrier group regardless of the ADH1B genotype (P&lt;0.001). Setting the cutoff for the acetaldehyde/ethanol ratio at 22.3×10–3 to include ALDH2*2 carriers yielded an accuracy for the detection of ALDH2*2 carriers of 96.3% (95% CI: 91.5–96.9%), sensitivity of 100%, and specificity of 92%. Conclusions: Our breath test may be a convenient screening tool for identifying those at high risk of upper aerodigestive tract cancer.

457 Role of Interferon γ-Inducible Protein 10 in the Pathogenesis of Non-Alcoholic Steatohepatitis

A S L D A b st ra ct s by mass spectrometry to diagnose NAFLD in overweight/ obese children. Methods: Patients were recruited from the Pediatric Preventive Cardiology and Metabolic Clinic. All patients were screened with an ultrasound of the abdomen to evaluate for the presence of NAFLD. Exhaled breath was collected and analyzed per protocol using selective ion flow tube (SIFTMS) to identify new markers of NAFLD. Results: Sixty patients were included in the study (37 with NAFLD on ultrasound and 23 with normal liver). All children were overweight or obese with a body mass index ≥ 85% for age. The mean age was 15± 3.1 years and 50% were female. A comparison of the SIFT-MS results of patients with NAFLD to those with normal liver on ultrasound revealed differences in concentration of more than 15 compounds. Discriminant analysis via stepwise variable selection of mass scanning ion peak data demonstrated five ion peaks that identified subjects with NAFLD with an accuracy of 90% (-2 log likelihood 0.172; Wilks' Lambda 0.145 (p , 0.0001)). Further analysis revealed that breath isoprene (cholesterol synthesis), acetone (glucose metabolism), trimethyamine (choline metabolism by microbiota), acetaldehyde (ethanol metabolism), and pentane (oxidative stress) were significantly higher in the NAFLD group compared to normal liver group, p value, 0.05 for all (Table). Conclusion: Exhaled breath analysis is a promising noninvasive method to detect fatty liver in obese children. Isoprene, acetone, trimethylamine, acetaldehyde, and pentane are novel biomarkers that may help to gain insight into pathophysiological processes and pathways leading to the development of NAFLD. Future studies are needed to validate our findings.

The quantification of carbon dioxide in humid air and exhaled breath by selected ion flow tube mass spectrometry

The reactions of carbon dioxide, CO(2), with the precursor ions used for selected ion flow tube mass spectrometry, SIFT-MS, analyses, viz. H(3)O(+), NO(+) and O(2) (+), are so slow that the presence of CO(2) in exhaled breath has, until recently, not had to be accounted for in SIFT-MS analyses of breath. This has, however, to be accounted for in the analysis of acetaldehyde in breath, because an overlap occurs of the monohydrate of protonated acetaldehyde and the weakly bound adduct ion, H(3)O(+)CO(2), formed by the slow association reaction of the precursor ion H(3)O(+) with CO(2) molecules. The understanding of the kinetics of formation and the loss rates of the relevant ions gained from experimentation using the new generation of more sensitive SIFT-MS instruments now allows accurate quantification of CO(2) in breath using the level of the H(3)O(+)CO(2) adduct ion. However, this is complicated by the rapid reaction of H(3)O(+)CO(2) with water vapour molecules, H(2)O, that are in abundance in exhaled breath. Thus, a study has been carried out of the formation of this adduct ion by the slow three-body association reaction of H(3)O(+) with CO(2) and its rapid loss in the two-body reaction with H(2)O molecules. It is seen that the signal level of the H(3)O(+)CO(2) adduct ion is sensitively dependent on the humidity (H(2)O concentration) of the sample to be analysed and a functional form of this dependence has been obtained. This has resulted in an appropriate extension of the SIFT-MS software and kinetics library that allows accurate measurement of CO(2) levels in air samples, ranging from very low percentage levels (0.03% typical of tropospheric air) to the 6% level that is about the upper limit in exhaled breath. Thus, the level of CO(2) can be traced through single time exhalation cycles along with that of water vapour, also close to the 6% level, and of trace gas metabolites that are present at only a few parts-per-billion. This has added a further dimension to the analysis of major and trace compounds in breath using SIFT-MS.

Analysis of breath, exhaled via the mouth and nose, and the air in the oral cavity

Analyses have been performed, using on-line selected ion flow tube mass spectrometry (SIFT-MS), of the breath of three healthy volunteers, as exhaled via the mouth and the nose and also of the air in the oral cavity during breath hold, each morning over a period of one month. Nine trace compounds have been quantified and concentration distributions have been constructed. Of these compounds, the levels of acetone, methanol and isoprene are the same in the mouth-exhaled and the nose-exhaled breath; hence, we deduce that these compounds are totally systemic. The levels of ammonia, ethanol and hydrogen cyanide are much lower in the nose-exhaled breath than in the mouth-exhaled breath and highest in the oral cavity, indicating that these compounds are largely generated in the mouth with little being released at the alveolar interface. Using the same ideas, both the low levels of propanol and acetaldehyde in mouth-exhaled breath appear to have both oral and systemic components. Formaldehyde is at levels in mouth- and nose-exhaled breath and the oral cavity that are lower than that of the ambient air and so its origin is difficult to ascertain, but it appears to be partially systemic. These results indicate that serious contamination of alveolar breath exhaled via the mouth can occur and if breath analysis is to be used to diagnose metabolic disease then analyses should be carried out of both mouth- and nose-exhaled breath to identify the major sources of particular trace compounds.

Influence of weakly bound adduct ions on breath trace gas analysis by selected ion flow tube mass spectrometry (SIFT-MS)

This paper describes how weakly bound adduct ions form when the precursor ions used in selected ion flow mass spectrometry, SIFT-MS, analyses, viz. H 3O +, NO + and O 2 +, associate with the major components of air and exhaled breath, N 2, O 2 and CO 2. These adduct ions, which include H 3O +N 2, H 3O +CO 2, NO +CO 2, O 2 +O 2 and O 2 +CO 2, are clearly seen when dry air containing 5% CO 2 (typical of that in exhaled breath) is analysed using SIFT-MS. These adduct ions must not be misinterpreted as characteristic product ions of trace gases; if so, serious analytical errors can result. However, when exhaled breath is analysed these adduct ions are partly removed by ligand switching reactions with the abundant water molecules and the problems they represent are alleviated. But the small fractions of the adduct ions that remain in the SIFT-MS spectra, and especially when they are isobaric with genuine characteristic product ion of breath trace gases, can result in erroneous quantifications; such is the case for H 3O +N 2 interfering with breath ethanol analysis and H 3O +CO 2 with breath acetaldehyde analysis. However, these difficulties can be overcome when the isobaric adduct ions are properly recognised and excluded from the analyses; then these two important compounds can be properly quantified in breath. The presence of O 2 +CO 2 in the product ion spectra interferes with the analysis of CS 2 present at low levels in exhaled breath. It is likely that similar problems will occur as other trace compounds are detected in exhaled breath when consideration will have to be given to the possibility of overlapping between their characteristic product ions and ions produced by hitherto unknown reactions. Similar problems are evident in other systems; for example, H 3O +CH 4 adduct ions are observed in both SIFT-MS analyses of methane rich mixtures like biologically generated waste gases and in model planetary atmospheres.

Quantification of trace levels of the potential cancer biomarkers formaldehyde, acetaldehyde and propanol in breath by SIFT-MS

The sensitivity of selected ion flow tube mass spectrometry, SIFT-MS, has been increased such that it is now possible to detect metabolites present at a part-per-billion, ppb, level in single breath exhalations. However, to utilize this improved sensitivity, the overlaps (coincidences) of those ions resulting from interfering reactions of impurity precursor ions with some breath metabolites present at higher concentrations with the analytical product ions characteristic of particular metabolites must be accounted for. In this paper, the full reaction schemes are presented for SIFT-MS analyses of three volatile potential cancer biomarkers in exhaled breath, namely formaldehyde, HCHO, acetaldehyde, CH3CHO and 2-propanol, CH3CH(OH)CH3, which identify both the characteristic SIFT-MS product ions for these compounds and the interfering ions at the same mass-to-charge, m/z, values. An absolute quantification equation accounting for these interferences is formulated and appropriate entries into the SIFT-MS kinetics library are indicated. It is shown that when using H3O+ to quantify formaldehyde and acetaldehyde the reactions of impurity O2+ ions with methanol and ethanol (always present in breath) must be accounted for and that the quantification of acetaldehyde must avoid the interference of the CO2 present in exhaled breath. Finally, it is indicated that the analysis of 2-propanol can be achieved using both H3O+ and NO+ precursor ions.

Miniaturized sample preparation needle: A versatile design for the rapid analysis of smoking-related compounds in hair and air samples

Miniaturized needle extraction device has been developed as a versatile sample preparation device designed for the rapid and simple analysis of smoking-related compounds in smokers’ hair samples and environmental tobacco smoke. Packed with polymeric particle, the resulting particle-packed needle was employed as a miniaturized sample preparation device for the analysis of typical volatile organic compounds in tobacco smoke. Introducing a bundle of polymer-coated filaments as the extraction medium, the needle was further applied as a novel sample preparation device containing simultaneous derivatization/extraction process of volatile aldehydes. Formaldehyde (FA) and acetaldehyde (AA) in smoker's breath during the smoking were successfully derivatized with two derivatization reagents in the polymer-coated fiber-packed needle device followed by the separation and determination in gas chromatography (GC). Smokers’ hair samples were also packed into the needle, allowing the direct extraction of nicotine from the hair sample in a conventional GC injector. Optimizing the main experimental parameters for each technique, successful determination of several smoking-related compounds with these needle extraction methods has been demonstrated.

A longitudinal study of ethanol and acetaldehyde in the exhaled breath of healthy volunteers using selected‐ion flow‐tube mass spectrometry

Selected-ion flow-tube mass spectrometry (SIFT-MS) has been used to monitor the volatile compounds in the exhaled breath of 30 volunteers (19 male, 11 female) over a 6-month period. Volunteers provided breath samples each week between 8:45 and 13:00 (before lunch), and the concentrations of several trace compounds were obtained. In this paper the focus is on ethanol and acetaldehyde, which were simultaneously quantified by SIFT-MS using H3O+ precursor ions. The mean ethanol level for all samples was 196 parts-per-billion (ppb) with a standard deviation of 244 ppb, and the range of values for breath samples analysed is 0 to 1663 ppb. The mean acetaldehyde level for all samples was 24 ppb with a standard deviation of 17 ppb, and the range of values for breath samples analysed is 0 to 104 ppb. Background (ambient air) levels of ethanol were around 50 ppb, whereas any background acetaldehyde was usually undetectable. Increased ethanol levels were observed if sweet drink/food had been consumed within the 2 h prior to providing the breath samples, but no increase was apparent when alcohol had been consumed the previous evening. The measured endogenous breath ethanol and acetaldehyde levels were not correlated. These data relating to healthy individuals are a prelude to using breath analysis for clinical diagnosis, for example, the recognition of bacterial overload in the gut (ethanol) or the possibly of detecting tumours in the body (acetaldehyde).

Coordinated FA-MS and SIFT-MS analyses of breath following ingestion of D2O and ethanol: total body water, dispersal kinetics and ethanol metabolism

A coordinated study of the dispersal of water between the various body compartments (stomach and gut, blood stream and tissue) and the similar dispersal kinetics of ethanol and its metabolism has been carried out involving two healthy volunteers using flowing afterglow mass spectrometry, FA-MS, and selected ion flow tube mass spectrometry, SIFT-MS. Thus, using these techniques, the variations of HDO and ethanol in breath, measured in successive single exhalations, were followed in real time after the ingestion of measured quantities of D2O and ethanol in proportion to the body weights of the subjects at the dose rates D2O ∼ 0.283 g kg–1, ethanol ∼0.067 g kg–1. During the FA-MS experimental periods (about 2 h), the dispersion of HDO into the body water and finally its equilibration in the total body water is observed from which total body water for each subject was determined. In the SIFT-MS measurements, the dispersion of ethanol into the body water and its loss via metabolism was observed until the physiological (pre-dose) breath level of ethanol for each individual was restored. A simple linear transformation is used to derive the time variations of the blood levels of HDO and ethanol. This has allowed a comparison of the fractions of the ingested ethanol that are metabolized during first-pass metabolism for the two subjects. Thus, in one subject 30% and in the other subject 40% of the ingested alcohol is metabolized in the first 20 min following ingestion. The good time resolution allowed by non-invasive breath analysis ensures that the rates of processes such as ethanol metabolism can be accurately measured. Simultaneous measurements of breath acetaldehyde (largely formed via the ethanol metabolism) and acetone were also performed during the SIFT-MS single breath exhalations.

Association between aldehyde dehydrogenase gene polymorphisms and the phenomenon of field cancerization in patients with head and neck cancer.

Patients with squamous-cell carcinoma in the head and neck (HNSCC) often develop second primary esophageal squamous-cell carcinomas (ESCC). In addition, widespread epithelial oncogenic alterations are also frequently observed in the esophagus and can be made visible as multiple Lugol-voiding lesions (multiple LVL) by Lugol chromoendoscopy. Multiple occurrences of neoplastic change in the upper aerodigestive tract have been explained by the concept of 'field cancerization', usually associated with repeated exposure to carcinogens such as alcohol and cigarette smoke. However, the etiology of second ESCC in HNSCC patients remains unclear and acetaldehyde, the first metabolite of ethanol, has been implicated as the ultimate carcinogen in alcohol-related carcinogenesis. We first investigated the relation between second ESCC and multiple LVL in 78 HNSCC patients. Multiple LVL and second ESCC were observed in 29 (37%) and 21 (27%) patients, respectively. All of the second ESCC were accompanied by multiple LVL. This may indicate that episodes of multiple LVL are precursors for second ESCC. We then examined the association of multiple LVL with the patients' characteristics, including genetic polymorphisms of the alcohol metabolizing enzymes, alcohol dehydrogenase type 3 (ADH3) and aldehyde dehydrogenase type 2 (ALDH2). We also investigated acetaldehyde concentrations in the breath of 52 of the 78 patients. All the patients with multiple LVL were both drinkers and smokers. Multivariable logistic analysis showed that the inactive ALDH2 allele (ALDH2-2) was the strongest contributing factor for the development of multiple LVL (odds ratio 17.6; 95% confidence intervals 4.7-65.3). After alcohol ingestion, acetaldehyde in the breath was elevated to a significantly higher level in all patients with the ALDH2-2 allele than in those without it. The high levels of breath acetaldehyde were significantly modified by the slow-metabolizing ADH3-2 allele. These results reveal strong evidence for a gene-environmental interaction between the ALDH2-2 allele and alcohol consumption, for the risk of developing multiple LVL, resulting in the development of second ESCC in patients with HNSCC. Ultimately, increased local acetaldehyde exposure thus appears to be a critical determinant of the phenomenon of 'field cancerization'.