Patterns and significance of exhaled-breath biomarkers in lung transplant recipients with acute allograft rejection

Sensitive Detection of OCS Using Thermal Conversion Combined with Spectral Reconstruction Filtering Differential Optical Absorption Spectroscopy

Carbonyl sulfide (OCS) is a toxic gas produced during industrial processes that poses risks to both human health and industrial equipment. Therefore, detecting OCS concentrations plays a crucial role in early hazard warning. This paper presents an online system for detecting OCS at the ppb level using thermal conversion and spectral reconstruction filtering differential optical absorption spectroscopy (SRF-DOAS). First, OCS, which is not suitable for DOAS due to its weak absorption characteristics, is completely transformed into SO2 with strong absorption characteristics under high-temperature conditions. Then, the spectral reconstruction filtering method (SRF) is proposed to eliminate the noise and interference. The core idea of the method is to arrange the spectrum according to the spectral intensity from small to large rather than wavelength, reconstructing the spectrum into a new spectrum with linear characteristics. The reconstructed spectrum can remove noise and interference by linear fitting and retain the characteristic of SO2 oscillation absorption. Next, we demonstrate the ability of the reconstructed spectral method to remove noise and interference by comparing the spectra of the inverse-reconstructed gas mixture and SO2. The relative deviation of 0.88% at 100 ppb and detection limit of 7.26 ppb*m for OCS were obtained using the SRF-DOAS method. Finally, the reliability of the system was confirmed by measurements of OCS concentrations in mixture gas of OCS and air, as well as in human exhaled breath.

Influence of ventilatory parameters on the concentration of exhaled volatile organic compounds in mechanically ventilated patients

Analysis of volatile organic compounds (VOC) within exhaled breath is subject to numerous sources of methodological and physiological variability. Whilst breathing pattern is expected to influence the concentrations of selected exhaled VOCs, it remains challenging to investigate respiratory rate and depth accurately in awake subjects. Online breath sampling was performed in 20 mechanically ventilated patients using proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS). The effect of variation in respiratory rate (RR) and tidal volume (TV) on the VOC release profiles was examined. A panel of nineteen VOCs were selected, including isoprene, acetone, propofol, volatile aldehydes, acids and phenols. Variation in RR had the greatest influence on exhaled isoprene levels, with maximum and average concentrations being inversely correlated with RR. Variations in RR had a statistically significant impact on acetone, C3-C7 linear aldehydes and acetic acid. In comparison, phenols (including propofol), C8-C10 aldehydes and C3-C6 carboxylic acids were not influenced by RR. Isoprene was the only compound to be influenced by variation in TV. These findings, obtained under controlled conditions, provide useful guidelines for the optimisation of breath sampling protocols to be applied on awake patients.

Smelling the Disease: Diagnostic Potential of Breath Analysis

Breath analysis is a relatively recent field of research with much promise in scientific and clinical studies. Breath contains endogenously produced volatile organic components (VOCs) resulting from metabolites of ingested precursors, gut and air-passage bacteria, environmental contacts, etc. Numerous recent studies have suggested changes in breath composition during the course of many diseases, and breath analysis may lead to the diagnosis of such diseases. Therefore, it is important to identify the disease-specific variations in the concentration of breath to diagnose the diseases. In this review, we explore methods that are used to detect VOCs in laboratory settings, VOC constituents in exhaled air and other body fluids (e.g., sweat, saliva, skin, urine, blood, fecal matter, vaginal secretions, etc.), VOC identification in various diseases, and recently developed electronic (E)-nose-based sensors to detect VOCs. Identifying such VOCs and applying them as disease-specific biomarkers to obtain accurate, reproducible, and fast disease diagnosis could serve as an alternative to traditional invasive diagnosis methods. However, the success of VOC-based identification of diseases is limited to laboratory settings. Large-scale clinical data are warranted for establishing the robustness of disease diagnosis. Also, to identify specific VOCs associated with illness states, extensive clinical trials must be performed using both analytical instruments and electronic noses equipped with stable and precise sensors.

N-thiocarboxyanhydrides, amino acid-derived enzyme-activated H2S donors, enhance sperm mitochondrial activity in presence and absence of oxidative stress

BACKGROUND

Hydrogen sulfide (H₂S) donors are crucial tools not only for understanding the role of H₂S in cellular function but also as promising therapeutic agents for oxidative stress-related diseases. This study aimed to explore the effect of amino acid-derived N-thiocarboxyanhydrides (NTAs), which release physiological H₂S levels in the presence of carbonic anhydrase, on porcine sperm function during short-term incubation with and without induced oxidative stress. For this purpose, we employed two H₂S-releasing NTAs with release half-lives (t_1/2) in the range of hours that derived from the amino acids glycine (Gly-NTA) or leucine (Leu-NTA). Because carbonic anhydrase is crucial for H₂S release from NTAs, we first measured the activity of this enzyme in the porcine ejaculate. Then, we tested the effect of Gly- and Leu-NTAs at 10 and 1 nM on sperm mitochondrial activity, plasma membrane integrity, acrosomal status, motility, motile subpopulations, and redox balance during short-term incubation at 38 °C with and without a reactive oxygen species (ROS)-generating system.

RESULTS

Our results show that carbonic anhydrase is found both in spermatozoa and seminal plasma, with activity notably higher in the latter. Both Gly- and Leu-NTAs did not exert any noxious effects, but they enhanced sperm mitochondrial activity in the presence and absence of oxidative stress. Moreover, NTAs (except for Leu-NTA 10 nM) tended to preserve the sperm redox balance against the injuries provoked by oxidative stress, which provide further support to the antioxidant effect of H₂S on sperm function. Both compounds also increased progressive motility over short-term incubation, which may translate into prolonged sperm survival.

CONCLUSIONS

The presence of carbonic anhydrase activity in mammalian spermatozoa makes NTAs promising molecules to investigate the role of H₂S in sperm biology. For the first time, beneficial effects of NTAs on mitochondrial activity have been found in mammalian cells in the presence and absence of oxidative stress. NTAs are interesting compounds to investigate the role of H₂S in sperm mitochondria-dependent events and to develop H₂S-related therapeutic protocols against oxidative stress in assisted reproductive technologies.

Volatolomics in healthcare and its advanced detection technology

Various diseases increasingly challenge the health status and life quality of human beings. Volatolome emitted from patients has been considered as a potential family of markers, volatolomics, for diagnosis/screening. There are two fundamental issues of volatolomics in healthcare. On one hand, the solid relationship between the volatolome and specific diseases needs to be clarified and verified. On the other hand, effective methods should be explored for the precise detection of volatolome. Several comprehensive review articles had been published in this field. However, a timely and systematical summary and elaboration is still desired. In this review article, the research methodology of volatolomics in healthcare is critically considered and given out, at first. Then, the sets of volatolome according to specific diseases through different body sources and the analytical instruments for their identifications are systematically summarized. Thirdly, the advanced electronic nose and photonic nose technologies for volatile organic compounds (VOCs) detection are well introduced. The existed obstacles and future perspectives are deeply thought and discussed. This article could give a good guidance to researchers in this interdisciplinary field, not only understanding the cutting-edge detection technologies for doctors (medicinal background), but also making reference to clarify the choice of aimed VOCs during the sensor research for chemists, materials scientists, electronics engineers, etc.

Acute Rejection in the Modern Lung Transplant Era

Acute cellular rejection (ACR) remains a common complication after lung transplantation. Mortality directly related to ACR is low and most patients respond to first-line immunosuppressive treatment. However, a subset of patients may develop refractory or recurrent ACR leading to an accelerated lung function decline and ultimately chronic lung allograft dysfunction. Infectious complications associated with the intensification of immunosuppression can also negatively impact long-term survival. In this review, we summarize the most recent evidence on the mechanisms, risk factors, diagnosis, treatment, and prognosis of ACR. We specifically focus on novel, promising biomarkers which are under investigation for their potential to improve the diagnostic performance of transbronchial biopsies. Finally, for each topic, we highlight current gaps in knowledge and areas for future research.

Measurement Device for Ambient Carbonyl Sulfide by Means of Catalytic Reduction Followed by Wet Scrubbing/Fluorescence Detection

A portable chemical analysis system for monitoring ambient carbonyl sulfide (COS) was investigated for the first time. COS is paid attention to from the perspectives of photosynthesis tracer, breath diagnosis marker, and new process-use in the manufacture of semiconductors. Recently, the threshold level value of COS was settled at 5 ppm in volume ratio (ppmv) for workplace safety management. In this work, COS was converted to H₂S by a small column packed with alumina catalyzer at 65 °C. Then, the H₂S produced was collected in a small channel scrubber to react with fluorescein mercuric acetate (FMA), and the resulting fluorescence quenching was monitored using an LED/photodiode-based miniature detector. The miniature channel scrubber was re-examined to determine its robustness and easy fabrication, and conditions of the catalyzer were optimized. When the FMA concentration used was 1 μM, the limit of detection and dynamic range, which were both proportional to the FMA concentration, were 0.07 and 25 ppbv, respectively. Ambient COS in the background level and even contaminated COS in the nitrogen gas cylinder could be detected. If necessary, H₂S was removed selectively by reproducible adsorbent columns. COS concentrations of engine exhaust were measured by the proposed method and by cryo-trap-gas chromatography-flame photometric detection, and the results obtained (0.5-5.9 ppbv) by the two methods agreed well (R ² = 0.945, n = 19). COS in ambient air and exhaust gases was successfully measured without any batchwise pretreatment.

Esterase-Triggered Self-Immolative Thiocarbamates Provide Insights into COS Cytotoxicity

Hydrogen sulfide (H₂S) is an important gasotransmitter and biomolecule, and many synthetic small-molecule H₂S donors have been developed for H₂S-related research. One important class of triggerable H₂S donors is self-immolative thiocarbamates, which function by releasing carbonyl sulfide (COS), which is rapidly converted to H₂S by the ubiquitous enzyme carbonic anhydrase (CA). Prior studies of esterase-triggered thiocarbamate donors reported significant inhibition of mitochondrial bioenergetics and toxicity when compared to direct sulfide donors, suggesting that COS may function differently than H₂S. Here, we report a suite of modular esterase-triggered self-immolative COS donors and include the synthesis, H₂S release profiles, and cytotoxicity of the developed donors. We demonstrate that the rate of ester hydrolysis correlates directly with the observed cytotoxicity in cell culture, which further supports the hypothesis that COS functions as more than a simple H₂S shuttle in certain biological systems.

A new way of monitoring mechanical ventilation by measurement of particle flow from the airways using Pexa method in vivo and during ex vivo lung perfusion in DCD lung transplantation

BACKGROUND

Different mechanical ventilation settings are known to affect lung preservation for lung transplantation. Measurement of particle flow in exhaled air may allow online assessment of the impact of ventilation before changes in the tissue can be observed. We hypothesized that by analyzing the particle flow, we could understand the impact of different ventilation parameters.

METHODS

Particle flow was monitored in vivo, post mortem, and in ex vivo lung perfusion (EVLP) in six porcines with the Pexa (particles in exhaled air) instrument. Volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) were used to compare small versus large tidal volumes. The surfactant lipids dipalmitoylphosphatidylcholine (DPPC) and phosphatidylcholine (PC) were quantified by mass spectrometry.

RESULTS

In vivo the particle mass in VCV¹ was significantly lower than in VCV² (p = 0.0186), and the particle mass was significantly higher in PCV¹ than in VCV¹ (p = 0.0322). In EVLP, the particle mass in VCV¹ was significantly higher than in PCV¹ (p = 0.0371), and the particle mass was significantly higher in PCV² than in PCV¹ (p = 0.0127). DPPC was significantly higher in EVLP than in vivo.

CONCLUSIONS

Here, we introduce a new method for measuring particle flow during mechanical ventilation and confirm that these particles can be collected and analyzed. VCV resulted in a lower particle flow in vivo but not in EVLP. In all settings, large tidal volumes resulted in increased particle flow. We found that DPPC was significantly increased comparing in vivo with EVLP. This technology may be useful for developing strategies to preserve the lung and has a high potential to detect biomarkers.

Breath volatile organic compounds of lung transplant recipients with and without chronic lung allograft dysfunction

INTRODUCTION

Chronic lung allograft dysfunction with its clinical correlative of bronchiolitis obliterans syndrome (BOS) remains the major limiting factor for long-term graft survival. Currently there are no established methods for the early diagnosis or prediction of BOS. To assess the feasibility of breath collection as a non-invasive tool and the potential of breath volatile organic compounds (VOC) for the early detection of BOS, we compared the breath VOC composition between transplant patients without and different stages of BOS.

METHODS

75 outpatients (25 BOS stage 0, 25 BOS stage 1 + 2, 25 BOS stage 3) after bilateral lung transplantation were included. Exclusion criteria were active smoking, oxygen therapy and acute infection. Patients inhaled room air through a VOC and sterile filter and exhaled into an aluminum reservoir tube. Breath was loaded directly onto Tenax^® TA adsorption tubes and was subsequently analyzed by gas-chromatography/mass-spectrometry.

RESULTS

The three groups were age and gender matched, but differed with respect to time since transplantation, the spectrum of underlying disease, and treatment regimes. Relative to patients without BOS, BOS stage 3 patients showed a larger number of different VOCs, and more pronounced differences in the level of VOCs as compared to BOS stage 1 + 2 patients. Logistic regression analysis found no differences between controls and BOS 1 + 2, but four VOCs (heptane, isopropyl-myristate, ethyl-acetate, ionone) with a significant contribution to the discrimination between controls and BOS stage 3. A combination of these four VOCs separated these groups with an area under the curve of 0.87.

CONCLUSION

Breath sample collection using our reservoir sampler in the clinical environment was feasible. Our results suggest that breath VOCs can discriminate severe BOS. However, convincing evidence for VOCs with a potential to detect early onset BOS is lacking.

Emerging Roles of Carbonyl Sulfide in Chemical Biology: Sulfide Transporter or Gasotransmitter?

SIGNIFICANCE

Carbonyl sulfide (COS) is the most prevalent sulfur-containing gas in the Earth's atmosphere, and it plays important roles in the global sulfur cycle. COS has been implicated in origin of life peptide ligation, is the primary energy source for certain bacteria, and has been detected in mammalian systems. Despite this long and intertwined history with terrestrial biology, limited attention has focused on potential roles of COS as a biological mediator. Recent Advances: Although bacterial COS production is well documented, definitive sources of mammalian COS production have not been confirmed. Enzymatic COS consumption in mammals, however, is well documented and occurs primarily by carbonic anhydrase (CA)-mediated conversion to hydrogen sulfide (H2S). COS has been detected in ex vivo mammalian tissue culture, as well as in exhaled breath as a potential biomarker for different disease pathologies, including cystic fibrosis and organ rejection. Recently, chemical tools for COS delivery have emerged and are poised to advance future investigations into the role of COS in different biological contexts.

CRITICAL ISSUES

Possible roles of COS as an important biomolecule, gasotransmitter, or sulfide transport intermediate remain to be determined. Key advances in both biological and chemical tools for COS research are needed to further investigate these questions.

FUTURE DIRECTIONS

Further evaluation of the biological roles of COS and disentangling the chemical biology of COS from that of H2S are needed to further elucidate these interactions. Chemical tools for COS delivery and modulation may provide a first avenue of investigative tools to answer many of these questions. Antioxid. Redox Signal. 28, 1516-1532.

Electronic Nose Technology Fails to Sniff Out Acute Mountain Sickness

Berendsen, Remco R., Marieke E. van Vessem, Marcel Bruins, Luc J.S.M. Teppema, Leon P.H.J. Aarts, and Bengt Kayser. Electronic nose technology fails to sniff out acute mountain sickness. High Alt Med Biol. 19:232-236, 2018.

AIM

The aim of the study was to evaluate whether an electronic nose can discriminate between individuals with and without acute mountain sickness (AMS) following rapid ascent to 4554 m.

RESULTS

We recruited recreational climbers (19 women, 82 men; age 35 ± 10 years, mean ± standard deviation [SD]) upon arrival at 4554 m (Capanna Regina Margherita, Italy) for a proof of concept study. AMS was assessed with the Lake Louise self-report score (LLSRS) and the abbreviated Environmental Symptoms Questionnaire (ESQc); scores ≥3 and ≥0.7 were considered AMS, respectively. Exhaled air was analyzed with an electronic nose (Aeonose; The eNose Company, Netherlands). The collected data were analyzed using an artificial neural network. AMS prevalence was 44% with the LLSRS (mean score of those sick 4.4 ± 1.4 [SD]) and 20% with the ESQc (1.2 ± 0.5). The electronic nose could not discriminate between AMS and no AMS (LLSRS p = 0.291; ESQc p = 0.805).

CONCLUSION

The electronic nose technology utilized in this study could not discriminate between climbers with and without symptoms of AMS in the setting of an acute exposure to an altitude of 4554 m. At this stage, we cannot fully exclude that this technology per se is not able to discriminate for AMS. The quest for objective means to diagnose AMS thus continues.

H2S and polysulfide metabolism: Conventional and unconventional pathways

It is now well established that hydrogen sulfide (H₂S) is an effector of a wide variety of physiological processes. It is also clear that many of the effects of H₂S are mediated through reactions with cysteine sulfur on regulatory proteins and most of these are not mediated directly by H₂S but require prior oxidation of H₂S and the formation of per- and polysulfides (H₂S_n, n = 2-8). Attendant with understanding the regulatory functions of H₂S and H₂S_n is an appreciation of the mechanisms that control, i.e., both increase and decrease, their production and catabolism. Although a number of standard "conventional" pathways have been described and well characterized, novel "unconventional" pathways are continuously being identified. This review summarizes our current knowledge of both the conventional and unconventional.

Inhibition of Mitochondrial Bioenergetics by Esterase-Triggered COS/H2S Donors

Hydrogen sulfide (H2S) is an important biological mediator, and synthetic H2S donating molecules provide an important class of investigative tools for H2S research. Here, we report esterase-activated H2S donors that function by first releasing carbonyl sulfide (COS), which is rapidly converted to H2S by the ubiquitous enzyme carbonic anhydrase (CA). We report the synthesis, self-immolative decomposition, and H2S release profiles of the developed scaffolds. In addition, the developed esterase-triggered COS/H2S donors exhibit higher levels of cytotoxicity than equivalent levels of Na2S or the common H2S donors GYY4137 and AP39. Using cellular bioenergetics measurements, we establish that the developed donors reduce cellular respiration and ATP synthesis in BEAS 2B human lung epithelial cells, which is consistent with COS/H2S inhibition of cytochrome c oxidase in the mitochondrial respiratory chain although not observed with common H2S donors at the same concentrations. Taken together, these results may suggest that COS functions differently than H2S in certain biological contexts or that the developed donors are more efficient at delivering H2S than other common H2S-releasing motifs.

Lung Cancer Screening Based on Type-different Sensor Arrays

In recent years, electronic nose (e-nose) systems have become a focus method for diagnosing pulmonary diseases such as lung cancer. However, principles and patterns of sensor responses in traditional e-nose systems are relatively homogeneous. Less study has been focused on type-different sensor arrays. In this paper, we designed a miniature e-nose system using 14 gas sensors of four types and its subsequent analysis of 52 breath samples. To investigate the performance of this system in identifying and distinguishing lung cancer from other respiratory diseases and healthy controls, five feature extraction algorithms and two classifiers were adopted. Lastly, the influence of type-different sensors on the identification ability of e-nose systems was analyzed. Results indicate that when using the LDA fuzzy 5-NN classification method, the sensitivity, specificity and accuracy of discriminating lung cancer patients from healthy controls with e-nose systems are 91.58%, 91.72% and 91.59%, respectively. Our findings also suggest that type-different sensors could significantly increase the diagnostic accuracy of e-nose systems. These results showed e-nose system proposed in this study was potentially practicable in lung cancer screening with a favorable performance. In addition, it is important for type-different sensors to be considered when developing e-nose systems.

Carbon disulfide. Just toxic or also bioregulatory and/or therapeutic?

The overview presented here has the goal of examining whether carbon disulfide (CS₂) may play a role as an endogenously generated bioregulator and/or has therapeutic value.

Quantification of propionaldehyde in breath of patients after lung transplantation

Oxygen-derived free radicals (ROS) have been identified to contribute significantly to ischemia-reperfusion (I/R) injury by initiating chain reactions with polyunsaturated membrane lipids (lipid peroxidation, LPO) resulting in the generation of several aldehydes and ketones. Due to their volatile nature these LPO products can be measured noninvasively in breath. We hypothesized that one of these markers, namely propionaldehyde, will be increased in lung and heart-lung transplant patients where severe oxidative stress due to I/R injury with early graft dysfunction represents one of the major postoperative complications resulting in prolonged ventilation and increased in-hospital morbidity and mortality. Expiratory air measurements for acetone, isoprene, and propionaldehyde were performed in seven patients after lung (n = 5) or heart-lung (n = 2) transplantation, ventilated patients (n = 12), and healthy volunteers (n = 17) using online ion-molecule reaction mass spectrometry. Increased concentrations of acetone (transplanted: 3812 [2347-12498]; ventilated: 1255 [276-1959]; healthy: 631 [520-784] ppbv; P < .001) and propionaldehyde (transplanted: 270 [70-424]; ventilated: 82 [41.8-142]; healthy: 1.7 [0.1-11.8] ppbv; P < .001) were found in expiratory air of transplanted and ventilated patients. Propionaldehyde resulting from spontaneous fragmentation of peroxides due to free radical-induced LPO after I/R injury in patients after lung or heart-lung transplantation can be quantified in expired breath.

Application of Cavity Enhanced Absorption Spectroscopy to the Detection of Nitric Oxide, Carbonyl Sulphide, and Ethane--Breath Biomarkers of Serious Diseases

The paper presents one of the laser absorption spectroscopy techniques as an effective tool for sensitive analysis of trace gas species in human breath. Characterization of nitric oxide, carbonyl sulphide and ethane, and the selection of their absorption lines are described. Experiments with some biomarkers showed that detection of pathogenic changes at the molecular level is possible using this technique. Thanks to cavity enhanced spectroscopy application, detection limits at the ppb-level and short measurements time (<3 s) were achieved. Absorption lines of reference samples of the selected volatile biomarkers were probed using a distributed feedback quantum cascade laser and a tunable laser system consisting of an optical parametric oscillator and difference frequency generator. Setup using the first source provided a detection limit of 30 ppb for nitric oxide and 250 ppb for carbonyl sulphide. During experiments employing a second laser, detection limits of 0.9 ppb and 0.3 ppb were obtained for carbonyl sulphide and ethane, respectively. The conducted experiments show that this type of diagnosis would significantly increase chances for effective therapy of some diseases. Additionally, it offers non-invasive and real time measurements, high sensitivity and selectivity as well as minimizing discomfort for patients. For that reason, such sensors can be used in screening for early detection of serious diseases.

Microextraction techniques in breath biomarker analysis

Breath volatile organic compound analysis may open a non-invasive window onto (patho)physiological and metabolic processes in the body. Breath tests require controlled sampling with respect to different breath phases and on-site and point-of-care applicability. Microextraction techniques such as solid phase microextraction (SPME) or needle-trap microextraction (NTME) meet these requirements. Small sample volumes and fast and controlled sample preparation combine on-site sampling and pre-concentration in one step. Detection limits in the low ppbV range and fast and simple processing facilitate the application of distribution-based SPME for screening and targeted analysis. Exhaustive NTME has shown further advantages such as fast and automated sampling, improved stability and reproducibility with improved detection limits. Combinations of different sorbents and thermal expansion desorption have shown most promising properties when applied to water saturated breath samples. This article addresses major challenges and advantages of microextraction techniques in breath analysis. Important progress, current applications and future trends are discussed.

Product ion distributions for the reactions of NO(+) with some physiologically significant volatile organosulfur and organoselenium compounds obtained using a selective reagent ionization time-of-flight mass spectrometer

RATIONALE

The reactions of NO(+) with volatile organic compounds (VOCs) in Selective Reagent Ionization Time-of-Flight Mass Spectrometry (SRI-TOF-MS) reactors are relatively poorly known, inhibiting their use for trace gas analysis. The rationale for this product ion distribution study was to identify the major product ions of the reactions of NO(+) ions with 13 organosulfur compounds and 2 organoselenium compounds in an SRI-TOF-MS instrument and thus to prepare the way for their analysis in exhaled breath, in skin emanations and in the headspace of urine, blood and cell and bacterial cultures.

METHODS

Product ion distributions have been investigated by a SRI-TOF-MS instrument at an E/N in the drift tube reactor of 130 Td for both dry air and humid air (4.9% absolute humidity) used as the matrix gas. The investigated species were five monosulfides (dimethyl sulfide, ethyl methyl sulfide, methyl propyl sulfide, allyl methyl sulfide and methyl 5-methyl-2-furyl sulfide), dimethyl disulfide, dimethyl trisulfide, thiophene, 2-methylthiophene, 3-methylthiophene, methanethiol, allyl isothiocyanate, dimethyl sulfoxide, and two selenium compounds - dimethyl selenide and dimethyl diselenide.

RESULTS

Charge transfer was seen to be the dominant reaction mechanism in all reactions under study forming the M(+) cations. For methanethiol and allyl isothiocyanate significant fractions were also observed of the stable adduct ions NO(+) M, formed by ion-molecule association, and [M-H](+) ions, formed by hydride ion transfer. Several other minor product channels are seen for most reactions indicating that the nascent excited intermediate (NOM)(+) * adduct ions partially fragment along other channels, most commonly by the elimination of neutral CH3 , CH4 and/or C2 H4 species that are probably bound to an NO molecule. Humidity had little effect on the product ion distributions.

CONCLUSIONS

The findings of this study are of particular importance for data interpretation in studies of volatile organosulfur and volatile organoselenium compounds employing SRI-TOF-MS in the NO(+) mode.

Solid-state gas sensors for breath analysis: a review

The analysis of volatile compounds is an efficient method to appraise information about the chemical composition of liquids and solids. This principle is applied to several practical applications, such as food analysis where many important features (e.g. freshness) can be directly inferred from the analysis of volatile compounds. The same approach can also be applied to a human body where the volatile compounds, collected from the skin, the breath or in the headspace of fluids, might contain information that could be used to diagnose several kinds of diseases. In particular, breath is widely studied and many diseases can be potentially detected from breath analysis. The most fascinating property of breath analysis is the non-invasiveness of the sample collection. Solid-state sensors are considered the natural complement to breath analysis, matching the non-invasiveness with typical sensor features such as low-cost, easiness of use, portability, and the integration with the information networks. Sensors based breath analysis is then expected to dramatically extend the diagnostic capabilities enabling the screening of large populations for the early diagnosis of pathologies. In the last years there has been an increased attention to the development of sensors specifically aimed to this purpose. These investigations involve both specific sensors designed to detect individual compounds and non-specific sensors, operated in array configurations, aimed at clustering subjects according to their health conditions. In this paper, the recent significant applications of these sensors to breath analysis are reviewed and discussed.

Analysis of exhaled breath for disease detection

Breath analysis is a young field of research with great clinical potential. As a result of this interest, researchers have developed new analytical techniques that permit real-time analysis of exhaled breath with breath-to-breath resolution in addition to the conventional central laboratory methods using gas chromatography-mass spectrometry. Breath tests are based on endogenously produced volatiles, metabolites of ingested precursors, metabolites produced by bacteria in the gut or the airways, or volatiles appearing after environmental exposure. The composition of exhaled breath may contain valuable information for patients presenting with asthma, renal and liver diseases, lung cancer, chronic obstructive pulmonary disease, inflammatory lung disease, or metabolic disorders. In addition, oxidative stress status may be monitored via volatile products of lipid peroxidation. Measurement of enzyme activity provides phenotypic information important in personalized medicine, whereas breath measurements provide insight into perturbations of the human exposome and can be interpreted as preclinical signals of adverse outcome pathways.

Hydrogen sulfide as a potential biomarker of asthma

Hydrogen sulfide (H2S), a gas characterized by the odor of rotten eggs, is produced by many cells in the airways and lungs, and may regulate physiologic and pathophysiologic processes. It plays a role in cellular signaling, and represents the third gasotransmitter after nitric oxide and carbon monoxide. Endogenous and exogenous H₂S have anti-inflammatory and anti-proliferative effects, with inhibitory effects in models of lung inflammation and fibrosis. Under certain conditions, H₂S may also be proinflammatory. It is generally a vasodilator and relaxant of airway and vascular smooth muscle cells. It acts as a reducing agent, being able to scavenge superoxide and peroxynitrite. H₂S is detectable in serum and in sputum supernatants with raised levels observed in asthmatics. The sputum levels correlated inversely with lung function. H₂S may play a role in the pathogenesis of asthma.

Standardised exhaled breath collection for the measurement of exhaled volatile organic compounds by proton transfer reaction mass spectrometry

Background

Exhaled breath volatile organic compound (VOC) analysis for airway disease monitoring is promising. However, contrary to nitric oxide the method for exhaled breath collection has not yet been standardized and the effects of expiratory flow and breath-hold have not been sufficiently studied. These manoeuvres may also reveal the origin of exhaled compounds.

Methods

15 healthy volunteers (34 ± 7 years) participated in the study. Subjects inhaled through their nose and exhaled immediately at two different flows (5 L/min and 10 L/min) into methylated polyethylene bags. In addition, the effect of a 20 s breath-hold following inhalation to total lung capacity was studied. The samples were analyzed for ethanol and acetone levels immediately using proton-transfer-reaction mass-spectrometer (PTR-MS, Logan Research, UK).

Results

Ethanol levels were negatively affected by expiratory flow rate (232.70 ± 33.50 ppb vs. 202.30 ± 27.28 ppb at 5 L/min and 10 L/min, respectively, p < 0.05), but remained unchanged following the breath hold (242.50 ± 34.53 vs. 237.90 ± 35.86 ppb, without and with breath hold, respectively, p = 0.11). On the contrary, acetone levels were increased following breath hold (1.50 ± 0.18 ppm) compared to the baseline levels (1.38 ± 0.15 ppm), but were not affected by expiratory flow (1.40 ± 0.14 ppm vs. 1.49 ± 0.14 ppm, 5 L/min vs. 10 L/min, respectively, p = 0.14). The diet had no significant effects on the gasses levels which showed good inter and intra session reproducibility.

Conclusions

Exhalation parameters such as expiratory flow and breath-hold may affect VOC levels significantly; therefore standardisation of exhaled VOC measurements is mandatory. Our preliminary results suggest a different origin in the respiratory tract for these two gasses.

3-sensor array for hand held breath diagnostic tool

Polymorphic transitions in nanocrystalline metal oxides leads to structural transformations resulting in differing properties at varying operating temperatures. Nanocrystalline MoO3 transforms from a metastable monoclinic phase to stable orthorhombic phase when heat treated in the temperature range of 420C to 500C. Gas sensing results have shown that at 420C MoO3 is sensitive to Isoprene, a 450C it shows sensitivity to CO2 and to ammonia at 500C. DSC data has proved that MoO3 changes crystal structure to monoclinic at 420C and to orthorhombic at about485C. This confirms a correlation between structure and gas sensing properties of MoO3. Using this knowledge a hand-held diagnostic tool is developed to monitor specific breath gases which can be biomarkers for diseases. The device consists of three sensors, the read-out gives a real time resistance value for each resistive sensor which is stored in a microprocessor. This is a one of a kind handheld tool for disease detection using ceramic sensors as detectors for gases which are known to be biomarkers for diseases.

Non-invasive assessment of exhaled breath pattern in patients with multiple chemical sensibility disorder

Multiple chemical sensitivity (MCS) is a complex disorder initiated by chemical exposure, particularly through the airways. MCS patients report sensitivity or intolerance to low levels of a wide spectrum of chemicals. Symptoms could include asthma-like signs, rhinitis, fatigue, cognitive dysfunction, psycho-physiological alteration, and other specific tissue reactions resembling hypoxic and oxidative stress effects. To recognize physiological signs that would allow the diagnosis of MCS in a non-invasive way we investigated the potential application of a new sensor system. In healthy volunteers, we measured exhaled breath content in the control condition and under exposure to olfactory stressors that mimic hypoxic or pollutant stressors playing a potential role in the generation of the MCS disorder. The recording system used is based on metal oxide semiconductor (MOS) sensor having a sensing range of 450-2,000 ppm CO(2) equivalents, which is able to detect a broad range of compounds playing a potential role in the generation of the MCS disorder, while correlating directly with the CO(2) levels. The results indicate that the recording system employed was suitable for the analysis of exhaled breath content in humans. Interestingly, the system was able to detect and discriminate between the exhaled breath content taken from the control condition and those from conditions under stress that mimicked exposures to pollutant or hypoxia. The results suggest that chronic hypoxia could be involved in the MCS disorder.

Exhaled acetone as a new biomaker of heart failure severity

BACKGROUND

Heart failure (HF) is associated with poor prognosis, and the identification of biomarkers of its severity could help in its treatment. In a pilot study, we observed high levels of acetone in the exhaled breath of patients with HF. The present study was designed to evaluate exhaled acetone as a biomarker of HF diagnosis and HF severity.

METHODS

Of 235 patients with systolic dysfunction evaluated between May 2009 and September 2010, 89 patients (HF group) fulfilled inclusion criteria and were compared with sex- and age-matched healthy subjects (control group, n = 20). Patients with HF were grouped according to clinical stability (acute decompensated HF [ADHF], n = 59; chronic HF, n = 30) and submitted to exhaled breath collection. Identification of chemical species was done by gas chromatography-mass spectrometry and quantification by spectrophotometry. Patients with diabetes were excluded.

RESULTS

The concentration of exhaled breath acetone (EBA) was higher in the HF group (median, 3.7 μg/L; interquartile range [IQR], 1.69-10.45 μg/L) than in the control group (median, 0.39 μg/L; IQR, 0.30-0.79 μg/L; P < .001) and higher in the ADHF group (median, 7.8 μg/L; IQR, 3.6-15.2 μg/L) than in the chronic HF group (median, 1.22 μg/L; IQR, 0.68-2.19 μg/L; P < .001). The accuracy and sensitivity of this method in the diagnosis of HF and ADHF were about 85%, a value similar to that obtained with B-type natriuretic peptide (BNP). EBA levels differed significantly as a function of severity of HF (New York Heart Association classification, P < .001). There was a positive correlation between EBA and BNP (r = 0.772, P < .001).

CONCLUSIONS

EBA not only is a promising noninvasive diagnostic method of HF with an accuracy equivalent to BNP but also a new biomarker of HF severity.

Breath biomarkers in diagnosis of pulmonary diseases

Breath analysis provides a convenient and simple alternative to traditional specimen testing in clinical laboratory diagnosis. As such, substantial research has been devoted to the analysis and identification of breath biomarkers. Development of new analytes enhances the desirability of breath analysis especially for patients who monitor daily biochemical parameters. Elucidating the physiologic significance of volatile substances in breath is essential for clinical use. This review describes the use of breath biomarkers in diagnosis of asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), lung cancer, as well as other pulmonary diseases. A number of breath biomarkers in lung pathophysiology will be described including nitric oxide (NO), carbon monoxide (CO), hydrogen peroxide (H₂O₂) and other hydrocarbons.

Mitochondrial adaptations to utilize hydrogen sulfide for energy and signaling

Sulfur is a versatile molecule with oxidation states ranging from -2 to +6. From the beginning, sulfur has been inexorably entwined with the evolution of organisms. Reduced sulfur, prevalent in the prebiotic Earth and supplied from interstellar sources, was an integral component of early life as it could provide energy through oxidization, even in a weakly oxidizing environment, and it spontaneously reacted with iron to form iron-sulfur clusters that became the earliest biological catalysts and structural components of cells. The ability to cycle sulfur between reduced and oxidized states may have been key in the great endosymbiotic event that incorporated a sulfide-oxidizing α-protobacteria into a host sulfide-reducing Archea, resulting in the eukaryotic cell. As eukaryotes slowly adapted from a sulfidic and anoxic (euxinic) world to one that was highly oxidizing, numerous mechanisms developed to deal with increasing oxidants; namely, oxygen, and decreasing sulfide. Because there is rarely any reduced sulfur in the present-day environment, sulfur was historically ignored by biologists, except for an occasional report of sulfide toxicity. Twenty-five years ago, it became evident that the organisms in sulfide-rich environments could synthesize ATP from sulfide, 10 years later came the realization that animals might use sulfide as a signaling molecule, and only within the last 4 years did it become apparent that even mammals could derive energy from sulfide generated in the gastrointestinal tract. It has also become evident that, even in the present-day oxic environment, cells can exploit the redox chemistry of sulfide, most notably as a physiological transducer of oxygen availability. This review will examine how the legacy of sulfide metabolism has shaped natural selection and how some of these ancient biochemical pathways are still employed by modern-day eukaryotes.

The message in the air: hydrogen sulfide metabolism in chronic respiratory diseases

Hydrogen sulfide (H(2)S) is an important gasotransmitter in the mammalian respiratory system. The enzymes that produce H(2)S - mainly cystathionine-β-synthase and cystathionine-γ-lyase - are expressed in pulmonary and airway tissues. Endogenous H(2)S participates in the regulation of the respiratory system's physiological functions and pathophysiological alterations, such as chronic obstructive pulmonary disease, asthma, pulmonary fibrosis and hypoxia-induced pulmonary hypertension, to name a few. The cellular targets of H(2)S in the respiratory system are diverse, including airway smooth muscle cells, epithelial cells, fibroblasts, and pulmonary artery smooth muscle cells. H(2)S also regulates respiratory functions such as airway constriction, pulmonary circulation, cell proliferation or apoptosis, fibrosis, oxidative stress, and neurogenic inflammation. Cross-talk between H(2)S and other gasotransmitters also affects the net outcome of lung function. The metabolism of H(2)S in the lungs and airway may serve as a biomarker for specific respiratory diseases. It is expected that strategies targeted at the metabolism and function of H(2)S will prove useful for the prevention and treatment of selective chronic respiratory diseases.

Laser spectroscopy on volatile sulfur compounds: possibilities for breath analysis

There is an emerging interest in the detection of volatile sulfur compounds (VSCs) in the breath environment, given their biological relevance as potential signatures of several pathological conditions. Particularly, laser-based spectroscopic sensors are candidates for conducting accurate breath diagnostics in clinical settings. With these aims in mind, the current status of VSC sensing via laser absorption spectroscopy is reviewed in this paper. Attention has been focused on the most promising exhaled markers of pathological conditions, namely hydrogen sulfide, carbonyl sulfide, methanethiol, carbon disulfide and dimethyl sulfide. Details of the most relevant spectroscopic studies conducted on such molecules are presented, together with suggestions on the future direction of this challenging analytical field.

The therapeutic potential of hydrogen sulfide: separating hype from hope

Hydrogen sulfide (H(2)S) has become the hot new signaling molecule that seemingly affects all organ systems and biological processes in which it has been investigated. It has also been shown to have both proinflammatory and anti-inflammatory actions and proapoptotic and anti-apoptotic effects and has even been reported to induce a hypometabolic state (suspended animation) in a few vertebrates. The exuberance over potential clinical applications of natural and synthetic H(2)S-"donating" compounds is understandable and a number of these function-targeted drugs have been developed and show clinical promise. However, the concentration of H(2)S in tissues and blood, as well as the intrinsic factors that affect these levels, has not been resolved, and it is imperative to address these points to distinguish between the physiological, pharmacological, and toxicological effects of this molecule. This review will provide an overview of H(2)S metabolism, a summary of many of its reported "physiological" actions, and it will discuss the recent development of a number of H(2)S-donating drugs that show clinical potential. It will also examine some of the misconceptions of H(2)S chemistry that have appeared in the literature and attempt to realign the definition of "physiological" H(2)S concentrations upon which much of this exuberance has been established.

A new portable monitor for measuring odorous compounds in oral, exhaled and nasal air

Background

The B/B Checker^®, a new portable device for detecting odorous compounds in oral, exhaled, and nasal air, is now available. As a single unit, this device is capable of detecting several kinds of gases mixed with volatile sulfur compounds (VSC) in addition to other odorous gasses. The purpose of the present study was to evaluate the effectiveness of the B/B Checker^® for detecting the malodor level of oral, exhaled, and nasal air.

Methods

A total of 30 healthy, non-smoking volunteers (16 males and 14 females) participated in this study. The malodor levels in oral, exhaled, and nasal air were measured using the B/B Checker^® and by organoleptic test (OT) scores. The VSCs in each air were also measured by gas chromatography (GC). Associations among B/B Checker^® measurements, OT scores and VSC levels were analyzed using Spearman correlation coefficients. In order to determine the appropriate B/B Checker^® level for screening subjects with malodor, sensitivity and specificity were calculated using OT scores as an identifier for diagnosing oral malodor.

Results

In oral and nasal air, the total VSC levels measured by GC significantly correlated to that measured by the B/B Checker^®. Significant correlation was observed between the results of OT scores and the B/B Checker^® measurements in oral (r = 0.892, p < 0.001), exhaled (r = 0.748, p < 0.001) and nasal air (r = 0.534, p < 0.001). The correlation between the OT scores and VSC levels was significant only for oral air (r = 0.790, p < 0.001) and nasal air (r = 0.431, p = 0.002); not for exhaled air (r = 0.310, p = 0.096). When the screening level of the B/B Checker^® was set to 50.0 for oral air, the sensitivity and specificity were 1.00 and 0.90, respectively. On the other hand, the screening level of the B/B Checker^® was set to 60.0 for exhaled air, the sensitivity and specificity were 0.82 and 1.00, respectively.

Conclusion

The B/B Checker^® is useful for objective evaluation of malodor in oral, exhaled and nasal air and for screening subjects with halitosis.

Trial registration

ClinicalTrials.gov: NCT01139073

Advances in electronic-nose technologies developed for biomedical applications

The research and development of new electronic-nose applications in the biomedical field has accelerated at a phenomenal rate over the past 25 years. Many innovative e-nose technologies have provided solutions and applications to a wide variety of complex biomedical and healthcare problems. The purposes of this review are to present a comprehensive analysis of past and recent biomedical research findings and developments of electronic-nose sensor technologies, and to identify current and future potential e-nose applications that will continue to advance the effectiveness and efficiency of biomedical treatments and healthcare services for many years. An abundance of electronic-nose applications has been developed for a variety of healthcare sectors including diagnostics, immunology, pathology, patient recovery, pharmacology, physical therapy, physiology, preventative medicine, remote healthcare, and wound and graft healing. Specific biomedical e-nose applications range from uses in biochemical testing, blood-compatibility evaluations, disease diagnoses, and drug delivery to monitoring of metabolic levels, organ dysfunctions, and patient conditions through telemedicine. This paper summarizes the major electronic-nose technologies developed for healthcare and biomedical applications since the late 1980s when electronic aroma detection technologies were first recognized to be potentially useful in providing effective solutions to problems in the healthcare industry.

Breath ammonia and trimethylamine allow real-time monitoring of haemodialysis efficacy

Non-invasive monitoring of breath ammonia and trimethylamine using Selected-ion-flow-tube mass spectroscopy (SIFT-MS) could provide a real-time alternative to current invasive techniques. Breath ammonia and trimethylamine were monitored by SIFT-MS before, during and after haemodialysis in 20 patients. In 15 patients (41 sessions), breath was collected hourly into Tedlar bags and analysed immediately (group A). During multiple dialyses over 8 days, five patients breathed directly into the SIFT-MS analyser every 30 min (group B). Pre- and post-dialysis direct breath concentrations were compared with urea reduction, Kt/V and creatinine concentrations. Dialysis decreased breath ammonia, but a transient increase occurred mid treatment in some patients. Trimethylamine decreased more rapidly than reported previously. Pre-dialysis breath ammonia correlated with pre-dialysis urea in group B (r(2) = 0.71) and with change in urea (group A, r(2) = 0.24; group B, r(2) = 0.74). In group B, ammonia correlated with change in creatinine (r(2) = 0.35), weight (r(2) = 0.52) and Kt/V (r(2) = 0.30). The ammonia reduction ratio correlated with the urea reduction ratio (URR) (r(2) = 0.42) and Kt/V (r(2) = 0.38). Pre-dialysis trimethylamine correlated with Kt/V (r(2) = 0.21), and the trimethylamine reduction ratio with URR (r(2) = 0.49) and Kt/V (r(2) = 0.36). Real-time breath analysis revealed previously unmeasurable differences in clearance kinetics of ammonia and trimethylamine. Breath ammonia is potentially useful in assessment of dialysis efficacy.

Detection of exhaled hydrogen sulphide gas in healthy human volunteers during intravenous administration of sodium sulphide

INTRODUCTION

Hydrogen sulphide (H(2)S) is an endogenous gaseous signaling molecule and potential therapeutic agent. Emerging studies indicate its therapeutic potential in a variety of cardiovascular diseases and in critical illness. Augmentation of endogenous sulphide concentrations by intravenous administration of sodium sulphide can be used for the delivery of H(2)S to the tissues. In the current study, we have measured H(2)S concentrations in the exhaled breath of healthy human volunteers subjected to increasing doses sodium sulphide in a human phase I safety and tolerability study.

METHODS

We have measured reactive sulphide in the blood via ex vivo derivatization of sulphide with monobromobimane to form sulphide-dibimane and blood concentrations of thiosulfate (major oxidative metabolite of sulphide) via ion chromatography. We have measured exhaled H(2)S concentrations using a custom-made device based on a sulphide gas detector (Interscan).

RESULTS

Administration of IK-1001, a parenteral formulation of Na(2)S (0.005-0.20 mg kg(-1), i.v., infused over 1 min) induced an elevation of blood sulphide and thiosulfate concentrations over baseline, which was observed within the first 1-5 min following administration of IK-1001 at 0.10 mg kg(-1) dose and higher. In all subjects, basal exhaled H(2)S was observed to be higher than the ambient concentration of H(2)S gas in room air, indicative of on-going endogenous H(2)S production in human subjects. Upon intravenous administration of Na(2)S, a rapid elevation of exhaled H(2)S concentrations was observed. The amount of exhaled H(2)S rapidly decreased after discontinuation of the infusion of Na(2)S.

CONCLUSION

Exhaled H(2)S represents a detectable route of elimination after parenteral administration of Na(2)S.

Breath analysis using laser spectroscopic techniques: breath biomarkers, spectral fingerprints, and detection limits

Breath analysis, a promising new field of medicine and medical instrumentation, potentially offers noninvasive, real-time, and point-of-care (POC) disease diagnostics and metabolic status monitoring. Numerous breath biomarkers have been detected and quantified so far by using the GC-MS technique. Recent advances in laser spectroscopic techniques and laser sources have driven breath analysis to new heights, moving from laboratory research to commercial reality. Laser spectroscopic detection techniques not only have high-sensitivity and high-selectivity, as equivalently offered by the MS-based techniques, but also have the advantageous features of near real-time response, low instrument costs, and POC function. Of the approximately 35 established breath biomarkers, such as acetone, ammonia, carbon dioxide, ethane, methane, and nitric oxide, 14 species in exhaled human breath have been analyzed by high-sensitivity laser spectroscopic techniques, namely, tunable diode laser absorption spectroscopy (TDLAS), cavity ringdown spectroscopy (CRDS), integrated cavity output spectroscopy (ICOS), cavity enhanced absorption spectroscopy (CEAS), cavity leak-out spectroscopy (CALOS), photoacoustic spectroscopy (PAS), quartz-enhanced photoacoustic spectroscopy (QEPAS), and optical frequency comb cavity-enhanced absorption spectroscopy (OFC-CEAS). Spectral fingerprints of the measured biomarkers span from the UV to the mid-IR spectral regions and the detection limits achieved by the laser techniques range from parts per million to parts per billion levels. Sensors using the laser spectroscopic techniques for a few breath biomarkers, e.g., carbon dioxide, nitric oxide, etc. are commercially available. This review presents an update on the latest developments in laser-based breath analysis.

Improved pre-concentration and detection methods for volatile sulphur breath constituents

Suitability of different types of pre-concentration (solid phase microextraction and sorbent trapping) and detection (flame photometric detector (FPD) and mass selective detector (MSD)) for gas chromatographic determination of sulphur-containing compounds (H2S, MeSH, EtSH, DMS, COS and CS2) in breath-gas was assessed in this study. Several factors like influence of humidity, influence of oxygen, or stability of target compounds in extraction vessels (SPME vials and sorbent tubes) were investigated. Despite poor stability of VSCs in SPME vials and matrix effects (unfavorable influence of humidity), SPME was found to be a fast and reliable enrichment method, which coupled with mass selective detector provided satisfactory LODs of target compounds at the ppt level (from 0.15 ppb for CS2 to 2.3 ppb for H2S). Application of sorbent trapping with two-bed sorbent tubes containing Tenax TA and Carboxen 1000 gave excellent LODs (0.03-0.3 ppb for 200 ml sample and MSD). Stability of investigated VSCs in sorbents was found to be very poor (30-40% losses after 2 h). FPD showed satisfactory sensitivity only when it was coupled with sorbent trapping. Breath samples were collected into Tedlar bags in a CO2-controlled manner. Humidity was removed during sampling (permeation dryer--Nafion) to avoid unfavorable water dependent effects during analysis.

Single-institution study evaluating the utility of surveillance bronchoscopy after lung transplantation

BACKGROUND

Many lung transplant physicians advocate surveillance bronchoscopy with transbronchial lung biopsy and bronchoalveolar lavage (TBB/BAL) to monitor lung recipients despite limited evidence this strategy improves outcomes. This report compares rates of infection (INF), acute rejection (AR), bronchiolitis obliterans syndrome (BOS) and survival in lung allograft recipients managed with surveillance TBB/BAL (SB) versus those with clinically indicated TBB/BAL (CIB).

METHODS

We reviewed 47 consecutive recipients transplanted between March 2002 and August 2005. Of these recipients, 24 consented to a multi-center trial requiring SB and 23 were managed by our usual practice of CIB. Rates of freedom from INF, AR, BOS and survival were compared. BOS and AR were diagnosed according to published guidelines from the International Society for Heart and Lung Transplantation.

RESULTS

A total of 240 TBB/BALs were performed. CIB and SB groups underwent 84 (3.7 +/- 3.4/patient) and 156 (6.5 +/- 2.0/patient) TBB/BALs, respectively. In the SB group, 54 (2.2 +/- 1.6/patient) TBB/BALs were true surveillance procedures, whereas 102 (4.2 +/- 2.3/patient) were clinically indicated. No AR episode requiring treatment was detected by true surveillance. Freedom from respiratory INF, AR, BOS and survival in the SB and CIB groups showed no significant differences. Five patients in the CIB group remained stable without requiring TBB/BAL. In the SB group, 4 previously asymptomatic patients developed pneumonia within 2 weeks of surveillance TBB/BAL.

CONCLUSIONS

With no obvious advantage identified, surveillance bronchoscopy may pose a risk to stable lung transplant recipients. A multi-center, controlled trial is required to validate the utility and safety of surveillance bronchoscopy in lung transplantation.

Human exhaled air analytics: biomarkers of diseases

Over the last few years, breath analysis for the routine monitoring of metabolic disorders has attracted a considerable amount of scientific interest, especially since breath sampling is a non-invasive technique, totally painless and agreeable to patients. The investigation of human breath samples with various analytical methods has shown a correlation between the concentration patterns of volatile organic compounds (VOCs) and the occurrence of certain diseases. It has been demonstrated that modern analytical instruments allow the determination of many compounds found in human breath both in normal and anomalous concentrations. The composition of exhaled breath in patients with, for example, lung cancer, inflammatory lung disease, hepatic or renal dysfunction and diabetes contains valuable information. Furthermore, the detection and quantification of oxidative stress, and its monitoring during surgery based on composition of exhaled breath, have made considerable progress. This paper gives an overview of the analytical techniques used for sample collection, preconcentration and analysis of human breath composition. The diagnostic potential of different disease-marking substances in human breath for a selection of diseases and the clinical applications of breath analysis are discussed.