Exhaled breath analysis in exercise and health

Research in the field of exhaled breath analysis is developing rapidly and is currently focussed on disease diagnosis and prognosis. The ability to identify early onset of life-threatening diseases, by a subtle change in exhaled profile that is picked up through a non-invasive measure, is of clinical interest. However, implementation of exhaled breath analysis can extend further beyond disease diagnosis and/or management. Using a non-invasive and rapid sample collection with high sensitivity, breath analysis may be seen to have potential benefit to the wider community. This research describes preliminary investigations into exhaled breath in exercise-based scenarios that aims to translate current breath analysis methodologies into a sport and exercise medicine context. An adaptive absorbent-based breath sampling methodology was used to collect a total of 220 breath samples from 54 participants over 3 studies. Breath volatiles were analysed using thermal desorption-gas chromatography-mass spectrometry. Data were analysed with targeted, and multivariate metabolomics-based approaches. Potential health impacts to high performance and recreational swimmers exposed to chlorinated water was studied. Following preliminary and scoping studies, 19 participants were sampled before a 30 min swim, and a further 5 times for 10 hrs after swimming. Environmental and control samples were also collected. Concentrations of chlorine-based disinfection by-products were observed to increase by up to a median of 121-fold, and take up to 8.5 hrs to return to pre-swimming levels. Metabolomic profiling identified the monoterpene geranylacetone to be a discriminant variable in samples taken 10 hrs after swimming. Geranylacetone is associated with membranes and extracellular fluids and an upregulated trend was observed across the five sampling time points post-swimming. Further research with an appropriately stratified and powered cohort (n=38) was recommended. The effects of intense exercise on breath profiles was explored for the possible use of breath analysis for exercise science with elite performance-based medicine. Twenty-nine participants provided exhaled breath samples before undergoing a maximal oxygen uptake (fitness) test and then provided 2 additional samples over the following 1 hr period. High and low fitness groupings, deemed by oxygen uptake values, were compared for exhaled metabolites. Lower exhaled acetone and isoprene were observed in participants with greater absolute oxygen uptake leading to a hypothesis for a non-invasive breath based fitness test. Finally, an interface for breath-by-breath analysis using a transportable mass spectrometer was developed. A controlled change in exhaled profiles was achieved through the ingestion of a peppermint oil capsule. Menthone was measured on-line and monitored for up to 10 hrs post-administration. Sixteen participants enabled the system to be demonstrated as exhaled menthone was at elevated concentrations for at least 6 hrs. Validation against thermal desorption-gas chromatography-mass spectrometry confirmed the system to be detecting metabolites at the sub-µg L-1 range

Gut microbial metabolites as mediators of renal disease: do short-chain fatty acids offer some hope?

Gut microbial metabolites as mediators of renal disease: do short-chain fatty acids offer some hope

B-type natriuretic peptide molecular forms for risk stratification and prediction of outcome after acute myocardial infarction

Background: B-type natriuretic peptide (BNP) is known to be a risk marker following acute myocardial infarction (MI). More recently, truncated molecular forms of the BNP molecule have been identified, with the association of these forms and outcome in acute MI not known. The present study investigated their use as risk stratifying biomarkers of this condition. Methods: BNP molecular forms (BNP 5-32, BNP 4-32 and BNP 3-32) were measured in plasma from 1,078 acute MI patients using immunocapture followed by MALDI-ToF-mass spectrometry. Associations of molecular forms with short-term and long-term adverse outcomes were assessed. Results: BNP molecular forms were independent predictors of mortality/reinfarction, mortality/rehospitalization due to heart failure, and a composite of all events at 6 months, 1 year and 2 years and showed prognostic ability comparable with conventional BNP measurements (P <0.001-0.026 vs. N-terminal [NT]-proBNP P <0.001-0.020, respectively). Reclassification analyses showed BNP molecular forms successfully reclassified patient risk when used in addition to the GRACE clinical risk score (P ≤0.005). BNP 5-32 showed utility as a secondary risk stratification biomarker when used in combination with the GRACE score and NT-proBNP by successful down-classification of high-risk patients. Conclusions: BNP molecular forms were associated with poor prognosis at 6 months, 1 year and at 2 years in patients with acute MI. BNP 5-32 showed successful utility as a secondary marker in combination with NT-proBNP after GRACE scoring. This study suggests a potential role for BNP molecular forms in prognosis and risk stratification after acute MI

The Impact of a Graded Maximal Exercise Protocol on Exhaled Volatile Organic Compounds:A Pilot Study

Exhaled volatile organic compounds (VOCs) are of interest due to their minimally invasive sampling procedure. Previous studies have investigated the impact of exercise, with evidence suggesting that breath VOCs reflect exercise-induced metabolic activity. However, these studies have yet to investigate the impact of maximal exercise to exhaustion on breath VOCs, which was the main aim of this study. Two-litre breath samples were collected onto thermal desorption tubes using a portable breath collection unit. Samples were collected pre-exercise, and at 10 and 60 min following a maximal exercise test (VO2MAX). Breath VOCs were analysed by thermal desorption-gas chromatography-mass spectrometry using a non-targeted approach. Data showed a tendency for reduced isoprene in samples at 10 min post-exercise, with a return to baseline by 60 min. However, inter-individual variation meant differences between baseline and 10 min could not be confirmed, although the 10 and 60 min timepoints were different (p = 0.041). In addition, baseline samples showed a tendency for both acetone and isoprene to be reduced in those with higher absolute VO2MAX scores (mL(O2)/min), although with restricted statistical power. Baseline samples could not differentiate between relative VO2MAX scores (mL(O2)/kg/min). In conclusion, these data support that isoprene levels are dynamic in response to exercise.</p

Biomarkers in Heart Failure and Associated Diseases

Biomarkers in heart failure and associated disease

Probiotics: current landscape and future horizons

In recent years there has been a rapid rise in interest for the application of probiotic supplements to act as mediators in health and disease. This appeal is predominantly due to ever-increasing evidence of the interaction of the microbiota and pathophysiological processes of disease within the human host. This narrative review considers the current landscape of the probiotic industry and its research, and discusses current pitfalls in the lack of translation from laboratory science to clinical application. Future considerations into how industry and academia must adapt probiotic research to maximize success are suggested, including more targeted application of probiotic strains dependent on individual capabilities as well as application of multiple advanced analytical technologies to further understand and accelerate microbiome science. Lay abstract: The global market for probiotic supplements is continually expanding. Despite the public perception of benefits provided by probiotics, the evidence to conclusively link probiotic strains to improved characteristics of health or disease is lacking. This is owing, in part, to the lack of large-scale research trials, but also to the insufficient understanding of the interactions occurring within the human system following supplementation. More in-depth research into individual probiotic strains, combined with the application of multiple advanced measurement techniques will provide a future direction for probiotic research and, in turn, aim to provide useful data to translate into routine healthcare practice

Simple, high-throughput measurement of gut-derived short-chain fatty acids in clinically relevant biofluids using gas chromatography-mass spectrometry

IntroductionThe quantitative measurement of circulating gut bacteria-derived metabolites has increased in recent years due to their associations with health and disease. While much of the previous attention has been placed on metabolites considered as deleterious to health, a shift to the investigation of short-chain fatty acids (SCFAs) as potential health promotors has been observed.ObjectivesTo develop a simple, high-throughput and quantitative assay to measure gut-derived SCFAs in clinically relevant biofluids using gas chromatography-mass spectrometry (GC–MS).MethodsA short (7.5 min) GC–MS assay was optimized for measurement of seven straight- and branched-chain SCFAs and their deuterated isotopes using a wax-based column for analysis without prior derivatization. The assay was validated using routine criteria to assess precision, accuracy, matrix effects, recovery, and extraction reproducibility. Assay applicability was tested in cohorts of healthy individuals and kidney disease patients.ResultsThe assay was demonstrated to be precise, accurate and reproducible with acceptable levels of matrix effect and analyte recovery. Lower limits of detection and quantitation were in the low ng/mL range. An investigation into different blood collection tube chemistries demonstrated that lithium heparin plasma and serum clotting activator tubes are recommended for use in future cross-study comparisons. Kidney disease patient analyses demonstrated variable differences across SCFAs when comparing hemodialysis to earlier stages of chronic kidney disease, demonstrating the suitability of the assay for translation to clinical analyses.ConclusionThe assay has been validated and identified as reliable for use in larger-scale studies for the analysis of SCFAs in human plasma and serum