Feasibility of perioperative volatile organic compound breath testing for prediction of paralytic ileus following laparoscopic colorectal resection.

BACKGROUND: Despite implementation of enhanced recovery after surgery (ERAS) and laparoscopic techniques, postoperative ileus (POI) remains frequent after colorectal surgery, impacting the patient, their recovery and health-care resources. Presently there are no tests that reliably predict or enable early POI diagnosis. Volatile organic compounds (VC) are products of human and microbiota cellular metabolism and we hypothesised that a detectable alteration occurs in POI. METHOD: This was a prospective observational study of patients undergoing laparoscopic colorectal resection within an established ERAS programme. Standardized end-expiratory breath sampling was performed on the morning of surgery and on the first three postoperative mornings. The concentrations of VCs commonly found in intestinal gas were analysed using selected ion flow tube mass spectrometry and GastroCH4 ECK®. Feasibility data, bowel preparation, postoperative oral intake, POI and 30-day morbidity were recorded. RESULTS: Of the 75 potentially eligible patients, 58 (77%) agreed to participate. Per-protocol breath sampling was successfully completed in 94%. There were no analytical failures. Baseline and postoperative concentrations of VCs were broadly comparable and were not altered by bowel preparation or postoperative oral intake. POI developed in 14 (29%) patients. Preoperative ammonia concentration was higher in patients who developed POI [830 parts per billion (ppb) vs 510 ppb, P = 0.027]. There was an increase in the concentration of acetic acid detected on day 2 in patients who developed POI (99 ppb vs 171 ppb, P = 0.021). CONCLUSION: Repeated VC breath sampling and analysis is feasible in the perioperative setting. An elevated ammonia concentration on the morning of surgery may be a potential predictor of POI.

A prospective genome-wide study of prostate cancer metastases reveals association of wnt pathway activation and increased cell cycle proliferation with primary resistance to abiraterone acetate-prednisone.

Background: Genomic aberrations have been identified in metastatic castration-resistant prostate cancer (mCRPC), but molecular predictors of resistance to abiraterone acetate/prednisone (AA/P) treatment are not known. Patients and methods: In a prospective clinical trial, mCRPC patients underwent whole-exome sequencing (n = 82) and RNA sequencing (n = 75) of metastatic biopsies before initiating AA/P with the objective of identifying genomic alterations associated with resistance to AA/P. Primary resistance was determined at 12 weeks of treatment using criteria for progression that included serum prostate-specific antigen measurement, bone and computerized tomography imaging and symptom assessments. Acquired resistance was determined using the end point of time to treatment change (TTTC), defined as time from enrollment until change in treatment from progressive disease. Associations of genomic and transcriptomic alterations with primary resistance were determined using logistic regression, Fisher's exact test, single and multivariate analyses. Cox regression models were utilized for determining association of genomic and transcriptomic alterations with TTTC. Results: At 12 weeks, 32 patients in the cohort had progressed (nonresponders). Median study follow-up was 32.1 months by which time 58 patients had switched treatments due to progression. Median TTTC was 10.1 months (interquartile range: 4.4-24.1). Genes in the Wnt/ß-catenin pathway were more frequently mutated and negative regulators of Wnt/ß-catenin signaling were more frequently deleted or displayed reduced mRNA expression in nonresponders. Additionally, mRNA expression of cell cycle regulatory genes was increased in nonresponders. In multivariate models, increased cell cycle proliferation scores (≥ 50) were associated with shorter TTTC (hazard ratio = 2.11, 95% confidence interval: 1.17-3.80; P = 0.01). Conclusions: Wnt/ß-catenin pathway activation and increased cell cycle progression scores can serve as molecular markers for predicting resistance to AA/P therapy.

Irritable bowel syndrome and active inflammatory bowel disease diagnosed by faecal gas analysis.

BACKGROUND: Inflammatory bowel disease and irritable bowel syndrome may present in a similar manner. Measuring faecal calprotectin concentration is often recommended to rule out inflammatory bowel disease, however, there are no tests to positively diagnose irritable bowel syndrome and invasive tests are still used to rule out other pathologies. AIM: To investigate a platform technology for diagnosing inflammatory bowel disease and irritable bowel syndrome based on faecal gas. METHODS: The platform technology is composed of a gas chromatography column coupled to a metal oxide gas sensor (OdoReader) and a computer algorithm. The OdoReader separates the volatile compounds from faecal gas and the computer algorithm identifies resistance patterns associated with specific medical conditions and builds classification models. This platform was applied to faecal samples from 152 patients: 33 patients with active inflammatory bowel disease; 50 patients with inactive inflammatory bowel disease; 28 patients with irritable bowel syndrome and 41 healthy donors (Control). RESULTS: The platform classified samples with accuracies from 75% to 100% using rigorous validation schemes: namely leave-one-out cross-validation, 10-fold cross-validation, double cross-validation and their Monte Carlo variations. The most clinically important findings, after double cross-validation, were the accuracy of active Crohn's disease vs. irritable bowel syndrome (87%; CI 84-89%) and irritable bowel syndrome vs. controls (78%; CI 76-80%). These schemes provide an estimate of out-of-sample predictive accuracy for similar populations. CONCLUSIONS: This is the first description of an investigation for the positive diagnosis of irritable bowel syndrome, and for diagnosing inflammatory bowel disease.

Investigation of faecal volatile organic metabolites as novel diagnostic biomarkers in inflammatory bowel disease.

BACKGROUND: The aetiology of inflammatory bowel disease (IBD) remains poorly understood. Recent evidence suggests an important role of gut microbial dysbiosis in IBD, and this may be associated with changes in faecal volatile organic metabolites (VOMs). AIM: To describe the changes in the faecal VOMs of patients with IBD and establish their diagnostic potential as non-invasive biomarkers. METHODS: Faecal samples were obtained from 117 people with Crohn's disease (CD), 100 with ulcerative colitis (UC), and 109 healthy controls. Faecal VOMs were extracted using solid-phase micro-extraction and analysed by gas chromatography mass spectrometry. Data analysis was carried out using partial least squares-discriminate analysis (PLS-DA) to determine class membership based on distinct metabolomic profiles. RESULTS: The PLS-DA model showed clear separation of active CD from inactive disease and healthy controls (P < 0.001). Heptanal, 1-octen-3-ol, 2-piperidinone and 6-methyl-2-heptanone were up-regulated in the active CD group [variable important in projection (VIP) score 2.8, 2.7, 2.6 and 2.4, respectively], while methanethiol, 3-methyl-phenol, short-chain fatty acids and ester derivatives were found to be less abundant (VIP score of 3.5, 2.6, 1.5 and 1.2, respectively). The PLS-DA model also separated patients with small bowel CD from healthy controls and those with colonic CD from UC (P < 0.001). In contrast, less distinct separation was observed between active UC, inactive UC and healthy controls. CONCLUSIONS: Analysis of faecal volatile organic metabolites can provide an understanding of gut metabolomic changes in IBD. It has the potential to provide a non-invasive means of diagnosing IBD, and can differentiate between UC and CD.

Transforming Growth Factor-ß3 Therapy Delays Postoperative Reossification and Improves Craniofacial Growth in Craniosynostotic Rabbits.

Postoperative reossification is a common clinical correlate following surgery. It has been suggested that an underexpression of transforming growth factor-ß3 (TGF-ß3) may be related to craniosynostosis and postoperative reossification. Adding TGF-ß3 may delay reossification and improve postoperative growth. The present study was designed to test this hypothesis. Thirty 10-day-old New Zealand white rabbits with hereditary coronal suture synostosis were divided into three groups: (1) suturectomy controls (n = 14), (2) suturectomy treated with bovine serum albumin (n = 8), and (3) suturectomy treated with TGF-ß3 protein (n = 8). At 10 days of age, a 3-mm × 15-mm coronal suturectomy was performed, and serial three-dimensional (3D) computed tomography (CT) scans and cephalographs were taken at 10, 25, 42, and 84 days of age. Calvaria were harvested at 84 days of age for histomorphometric analysis. Mean differences were analyzed using a group by age analysis of variance. Analysis of the 3D CT scan data revealed that sites treated with TGF-ß3 had significantly (P < .05) greater defect areas and significantly (P < .05) greater intracranial volumes through 84 days of age compared with controls. Histomorphometry showed that sites treated with TGF-ß3 had patent suturectomy sites and significantly (P < .001) less new bone in the suturectomy site compared with controls. Serial radiograph data revealed significant (P < .05) differences in craniofacial growth from 25 to 84 days in TGF-ß3-treated rabbits compared with controls. Data show that TGF-ß3 administration delayed reossification and improved craniofacial growth in this rabbit model. These findings also suggest that this molecular-based therapy may have potential clinical use.

The use of a gas chromatograph coupled to a metal oxide sensor for rapid assessment of stool samples from irritable bowel syndrome and inflammatory bowel disease patients.

There is much clinical interest in the development of a low-cost and reliable test for diagnosing inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), two very distinct diseases that can present with similar symptoms. The assessment of stool samples for the diagnosis of gastro-intestinal diseases is in principle an ideal non-invasive testing method. This paper presents an approach to stool analysis using headspace gas chromatography and a single metal oxide sensor coupled to artificial neural network software. Currently, the system is able to distinguish samples from patients with IBS from patients with IBD with a sensitivity and specificity of 76% and 88% respectively, with an overall mean predictive accuracy of 76%.

A review of the volatiles from the healthy human body.

A compendium of all the volatile organic compounds (VOCs) emanating from the human body (the volatolome) is for the first time reported. 1840 VOCs have been assigned from breath (872), saliva (359), blood (154), milk (256), skin secretions (532) urine (279), and faeces (381) in apparently healthy individuals. Compounds were assigned CAS registry numbers and named according to a common convention where possible. The compounds have been grouped into tables according to their chemical class or functionality to permit easy comparison. Some clear differences are observed, for instance, a lack of esters in urine with a high number in faeces. Careful use of the database is needed. The numbers may not be a true reflection of the actual VOCs present from each bodily excretion. The lack of a compound could be due to the techniques used or reflect the intensity of effort e.g. there are few publications on VOCs from blood compared to a large number on VOCs in breath. The large number of volatiles reported from skin is partly due to the methodologies used, e.g. collecting excretions on glass beads and then heating to desorb VOCs. All compounds have been included as reported (unless there was a clear discrepancy between name and chemical structure), but there may be some mistaken assignations arising from the original publications, particularly for isomers. It is the authors' intention that this database will not only be a useful database of VOCs listed in the literature, but will stimulate further study of VOCs from healthy individuals. Establishing a list of volatiles emanating from healthy individuals and increased understanding of VOC metabolic pathways is an important step for differentiating between diseases using VOCs.

Towards point of care testing for C. difficile infection by volatile profiling, using the combination of a short multi-capillary gas chromatography column with metal oxide sensor detection.

Rapid volatile profiling of stool sample headspace was achieved using a combination of short multi-capillary chromatography column (SMCC), highly sensitive heated metal oxide semiconductor (MOS) sensor and artificial neural network (ANN) software. For direct analysis of biological samples this prototype offers alternatives to conventional GC detectors and electronic nose technology. The performance was compared to an identical instrument incorporating a long single capillary column (LSCC). The ability of the prototypes to separate complex mixtures was assessed using gas standards and homogenised in house 'standard' stool samples, with both capable of detecting more than 24 peaks per sample. The elution time was considerably faster with the SMCC resulting in a run time of 10 minutes compared to 30 minutes for the LSCC. The diagnostic potential of the prototypes was assessed using 50 C. difficile positive and 50 negative samples. The prototypes demonstrated similar capability of discriminating between positive and negative samples with sensitivity and specificity of 85% and 80% respectively. C. difficile is an important cause of hospital acquired diarrhoea, with significant morbidity and mortality around the world. A device capable of rapidly diagnosing the disease at the point of care would reduce cases, deaths and financial burden.

The importance of methane breath testing: a review.

Sugar malabsorption in the bowel can lead to bloating, cramps, diarrhea and other symptoms of irritable bowel syndrome as well as affecting absorption of other nutrients. The hydrogen breath test is now a well established noninvasive test for assessing malabsorption of sugars in the small intestine. However, there are patients who can suffer from the same spectrum of malabsorption issues but who produce little or no hydrogen, instead producing relatively large amounts of methane. These patients will avoid detection with the traditional breath test for malabsorption based on hydrogen detection. Likewise the hydrogen breath test is an established method for small intestinal bacterial overgrowth (SIBO) diagnoses. Therefore, a number of false negatives would be expected for patients who solely produce methane. Usually patients produce either hydrogen or methane, and only rarely there are significant co-producers, as typically the methane is produced at the expense of hydrogen by microbial conversion of carbon dioxide. Various studies show that methanogens occur in about a third of all adult humans; therefore, there is significant potential for malabsorbers to remain undiagnosed if a simple hydrogen breath test is used. As an example, the hydrogen-based lactose malabsorption test is considered to result in about 5-15% false negatives mainly due to methane production. Until recently methane measurements were more in the domain of research laboratories, unlike hydrogen analyses which can now be undertaken at a relatively low cost mainly due to the invention of reliable electrochemical hydrogen sensors. More recently, simpler lower cost instrumentation has become commercially available which can directly measure both hydrogen and methane simultaneously on human breath. This makes more widespread clinical testing a realistic possibility. The production of small amounts of hydrogen and/or methane does not normally produce symptoms, whereas the production of higher levels can lead to a wide range of symptoms ranging from functional disorders of the bowel to low level depression. It is possible that excess methane levels may have more health consequences than excess hydrogen levels. This review describes the health consequences of methane production in humans and animals including a summary of the state of the art in detection methods. In conclusion, the combined measurement of hydrogen and methane should offer considerable improvement in the diagnosis of malabsorption syndromes and SIBO when compared with a single hydrogen breath test.

Volatiles from oral anaerobes confounding breath biomarker discovery.

The levels of compounds in exhaled mouth air do not necessarily reflect levels in the systemic circulation as bacteria can bio-transform substrates to produce compounds within the mouth. This should be of concern to researchers measuring breath volatiles with the aim of diagnosing systemic or metabolic conditions as very little is known about the origin of many compounds detected on the breath. This pilot study investigated the production of volatile compounds by bacterial communities present within the mouth. Solid-phase micro-extraction was used to extract volatiles from the headspace gas of two Gram-positive and two Gram-negative bacterial cultures known to be present within the mouth and from tongue biofilm microflora. Analyses were undertaken using gas chromatography mass spectrometry. Between 64 and 82 volatile compounds were detected from sampling the headspace gas above each of the cultures. Gram-negative anaerobes were found to produce more volatile sulfur compounds (VSCs) and amines. Solobacterium moorei, a Gram-positive species was however found to produce higher levels of acids, hydrocarbons, alcohols and aldehydes than the other species studied. Tongue-scrape biofilm systems at lower pH gave more hydrocarbons, ketones and fatty acids whilst at higher pH more alcohols, aldehydes, VSCs and amines were detected in the headspace. The results show that a number of compounds detected in mouth breath are produced by anaerobic bacteria in tongue biofilms. Thus, the contribution of volatiles from oral anaerobes cannot be ignored and more research is required to identify the major source of breath compounds as this will help determine their clinical significance as indicators of systemic disease or metabolic disorders in the body.

Syndromic micrognathia and peri-natal management with the ex-utero intra-partum treatment (EXIT) procedure.

Many advances in healthcare are built on advances in technology. In the case of fetal medicine, technology has availed an entirely new patient population. The authors report a case of severe micrognathia and Pierre Robin Sequence that was diagnosed prenatally. Antenatal planning and treatment were instituted via the Fetal Diagnosis/Treatment Team to avoid loss of the neonate's airway. An EXIT procedure was utilized to ensure a secure airway. The benefits of team care for these types of deformities are highlighted including the importance of craniomaxillofacial specialists.

A sensor system for monitoring the simple gases hydrogen, carbon monoxide, hydrogen sulfide, ammonia and ethanol in exhaled breath.

A sensor array system was constructed incorporating electrochemical sensors for hydrogen, carbon monoxide, hydrogen sulfide and ethanol, a ceramic sensor for total volatiles and a dye-based optical ammonia sensor. The system was calibrated using standard gases balanced with dry air. Limit of detection and % relative standard deviation values (n = 10) for the sensors in the array are hydrogen (0.1 ppm, 2.6%), carbon monoxide (0.4 ppm, 2.1%), ethanol (0.5 ppm, 1.5%), hydrogen sulfide (0.1 ppm, 1.5%) and ammonia (0.6 ppm, 10.7%). Humidity effects were assessed by calibrating with humidified standard gases (hydrogen, carbon monoxide) or spiked breath samples in Tedlar bags (hydrogen sulfide, ethanol and ammonia). The calibration data were used to establish a cross-sensitivity matrix. The concentration of breath volatiles was found to be dependent on exhalation rate and exhalation volume. A test protocol based on these data required volunteers to exhale 1 litre of breath at a rate between 7.5 and 17.5 l min(-1). Sensor responses were measured for 40 s then purged at 7 l min(-1) (150 s). A longitudinal study was undertaken of ten asymptomatic volunteers over a five-day period. Volunteers ate an ad hoc diet, but fasted prior to giving the first breath sample and then gave samples every hour for 8 h. Breath hydrogen levels for volunteers showed large variations within a day and also from day to day. Fasting levels ranged between 0.3 and 34.1 ppm (mean 9.1 ppm). The carbon monoxide levels for non-smokers were between 0.6 and 4.9 ppm (mean 2.1 ppm), whilst for smokers they were between 8.3 and 18.7 ppm (mean 12.8 ppm). The measured levels of other gases on breath were as follows: hydrogen sulfide (0-1.3 ppm, mean 0.33 ppm), ethanol (0-3.9 ppm, mean 0.62 ppm) and ammonia (0-1.3 ppm mean 0.42 ppm). The system was capable of direct quantitative measurements of low concentrations of a range of volatiles on exhaled breath. The measured values for compounds on the breath of asymptomatic volunteers were in broad agreement with quoted literature ranges. The system will now be assessed in a clinical setting.

The characteristics of novel low-cost sensors for volatile biomarker detection.

For breath analyses, volatile detectors capable of sensing extremely low concentrations in the sub-ppm range are required. Novel room temperature sensors were fabricated based on ultraviolet light activation of nanoparticulate metal oxide surfaces using light emitting diodes. These sensors gave reversible electrical resistance changes in the low ppm/ppb range to volatile organic compounds found in breath, including acetone, acetaldehyde, pentane and ethanol.

A comparative study of the analysis of human urine headspace using gas chromatography-mass spectrometry.

First-void urine samples were obtained from 24 elderly, asymptomatic men (median age 62.9 years). The headspace above pH adjusted urine samples were extracted using a carboxen/polydimethylsiloxane solid phase micro-extraction fibre and the volatile organic compounds analysed by gas chromatography/mass spectrometry. A total of 147 compounds were identified in the headspace of urine. The acidified samples recorded a total of 92 compounds, 27 of which were ubiquitous, basified samples 70 compounds, with 12 ubiquitous and unmodified pH samples 49, with 6 ubiquitous. Five compounds were ubiquitous irrespective of pH: acetone, methylene chloride, 4-heptanone, 2-pentanone and 2-butanone. A comparative analysis of unfrozen and frozen-thawed urine (stored at room temperature for 0, 1 and 8 h) showed that samples retained the same number of compounds although variations in the peak areas for some compounds were observed.

An analysis of volatiles in the headspace of the faeces of neonates.

A gas chromatography/mass spectrometry (GCMS) analysis of the headspace from the faeces of neonates was undertaken to record the volatiles associated with preterm babies on a neonatal unit. The compounds ethanol, acetone, 2-ethyl-1-hexanol, 3-methylbutanal, hexanal and 2,3-butanedione occurred with the highest frequency. The volatiles analysed were then compared to a previously published study of the volatiles from asymptomatic adult faeces. Fewer compounds were found in the neonatal faeces and virtually no sulfides were detected, in contrast to the adult samples where carbon disulfide, dimethyl disulfide and dimethyl sulfide were ubiquitous. In addition, 7 of the most abundant 15 volatile compounds were found to be aldehydes, while in contrast only 2, acetaldehyde and benzaldehyde, were present in the most abundant 15 compounds found in the headspace of adult faeces. 2-Ethyl-1-hexanol was considerably more abundant in the neonate stool compared to adult stool, and probably reflects high exposure to plastic materials containing plasticizers. The potential of disease diagnoses from the analysis of volatiles emitted from neonate faeces is discussed.

The rapid detection of methyl tert-butyl ether (MtBE) in water using a prototype gas sensor system.

The gasoline additive Methyl-tertiary-Butyl Ether (MtBE) is the second most common contaminant of groundwater in the USA and represents an important soil contaminant. This compound has been detected in the groundwater in at least 27 states as a result of leaking underground storage facilities (gasoline storage tanks and pipelines). Since the health effects of MtBE are unclear the potential threat to drinking water supplies is serious. Therefore, the ability to detect MtBE at low levels (ppb) and on-line at high-risk groundwater sites would be highly desirable. This paper reports the use of 'commercial' and metal oxide sensor arrays for the detection of MtBE in drinking and surface waters at low ppb level (microg.L(-1) range). The output responses from some of the sensors were found to correlate well with MtBE concentrations under laboratory conditions.

Medical recommendations as joint social practice.

Treatment plans can be thought of as one of the products of a medical interaction. As such, treatment for illness has been investigated as an outcome measure and seems to reflect bias in some areas of the practice of medicine. Although the evidence for patterns of differential treatment is compelling, determining the source of treatment bias has been difficult. Based on detailed analysis of transcripts of actual interactions in general medicine and oncology clinics, we propose that treatment plans are negotiated through everyday language practices that work to maximize agreement. We demonstrate that, on the level of individual medical encounters, patient agency is both apparent and operative and that physician power does not unilaterally determine outcomes. Thus, this investigation goes beyond the abstract study of physician and patient preferences or prejudices, focusing closely on the consequences of actual talk in settings where medical recommendations are being made.

A protocol for uvulopalatopharyngoplasty, mortised genioplasty, and maxillomandibular advancement in patients with obstructive sleep apnea: an analysis of 40 cases.

PURPOSE: This study evaluated the effectiveness of uvulopalatopharyngoplasty (UPPP) with mortised genioplasty and maxillomandibular advancement (MMA) for the treatment of patients with obstructive sleep apnea not controllable with appliances or continuous positive airway pressure. METHODS: Forty patients with obstructive sleep apnea were evaluated retrospectively. Thirty-three patients underwent combined UPPP and a modified mortised genioglossus advancement. Patients who had specific indications for MMA underwent combined procedures, eliminating staging of multiple surgeries. Seven patients were in this group. All patients were evaluated preoperatively and postoperatively with polysomnography to evaluate the efficacy of the treatment. RESULTS: Mean respiratory distress indices (RDI) and nadir oxyhemoglobin desaturation values were significantly improved with each of the therapies despite many patients having body mass indices significantly greater than the average quoted in other studies. Patients with moderate sleep apnea (RDI, 21 to 40) who underwent UPPP/genioglossus advancement did very well, with 86% of patients achieving success. Patients who underwent MMA all decreased their RDI by at least 56% and had an average improvement of 86%. CONCLUSIONS: The UPPP/mortised genioglossus advancement is effective for the treatment of obstructive sleep apnea. Maxillomandibular advancement is effective for treating severe sleep apnea and may, in some cases, be indicated in combination with UPPP/mortised genioglossus advancement to avoid multiple procedures. Surgical reconstruction of the upper airway is a reasonable approach to the treatment of patients with obstructive sleep apnea, and can be approached more directly to minimize repeated surgical intervention.