Applying the indicator amino acid oxidation technique in the domestic cat: results of a pilot study and development of a non-steady state prediction model.

The aim of this study was to evaluate whether the indicator amino acid oxidation (IAAO) method could be applied in the domestic cat. Six adult male cats were used in a replicated 3 × 3 Latin square design. Three semi-synthetic diets were developed: a methionine (Met) and total sulfur AA (TSAA) deficient diet (T-BASAL; 0.24% Met+Cys - DM basis) and two Met and TSAA-sufficient diets in which either dl-Met (T-DLM) or 2-hydroxy-4-(methylthio)-butanoic acid (T-MHA) were supplemented, respectively, on an equimolar basis to meet the TSAA requirement (0.34%). After a 2-d diet adaptation, IAAO studies were performed. Cats were offered 13 small meals. The sixth meal contained a priming dose (4.8 mg/kg-BW) of l-[1-13C]-Phe and the remaining meals a constant dose (1.04 mg/kg-BW). Breath samples were collected every 25 min to measure 13CO2 enrichment. The following morning, fasted blood samples were collected. Cats returned to the T-BASAL top dressed with a dl-Met solution for 4 d prior to being fed a new dietary treatment. Isotopic steady state was evaluated through visual inspection. Data were analyzed using PROC GLIMMIX procedure in SAS 9.4. While 13CO2 enrichment was successfully captured in breath samples, cats failed to reach 13CO2 steady state. Thus, a non-steady state isotope model was developed and coded in ACSLX (V3.1.4.2) individually for each cat on each study day to predict 13CO2 enrichment, and then, calculate oxidation of l-[1-13C]-Phe (F13CO2). A higher predicted F13CO2 was observed for cats fed T-BASAL compared to the others (P < 0.05), while no differences were observed between T-DLM and T-MHA (P > 0.05). Cats fed T-DLM tended to have higher plasma Met concentrations compared to those fed T-BASAL with cats fed T-MHA intermediate (P = 0.0867). Plasma homocysteine concentrations were higher in cats fed T-BASAL compared to the others (P < 0.05), while threonine concentrations tended to be higher in cats fed T-BASAL compared to those fed T-MHA (P = 0.0750). In conclusion, short-term provision of a semi-synthetic diet deficient in Met may elicit a metabolic response aiming to conserve Met. The successful quantification of 13CO2 enrichment in breath and the higher predicted F13CO2 in cats fed a Met deficient diet suggest that the IAAO technique may be used in cats. Adaptations in the isotope protocol should be made to achieve 13CO2 steady state in breath and avoid mathematical modeling to predict F13CO2.

It is necessary to apply more sensitive techniques to improve our limited understanding of amino acid (AA) requirements of adult cats. The non-invasive indicator amino acid oxidation (IAAO) technique is highly sensitive in mature animals. However, while it has been widely applied in different species, this technique has yet to be used in cats. We used six healthy adult cats to evaluate whether the IAAO method could be successfully applied in this species. A similar continuous small meals regimen as reported in IAAO studies in dogs was used. An oral primed-constant isotope infusion protocol was applied where l-13C-Phenylalanine (l-[1-13C]-Phe) was used as the tracer and the oxidation of l-[1-13C]-Phe as the response of interest. Breath samples were collected to determine enrichment of 13CO2 in breath and calculate oxidation of l-[1-13C]-Phe. While we were able to collect breath samples using calorimetry chambers and capture enrichment of 13CO2 in breath, cats did not achieve steady state, which is necessary to calculate oxidation of l-[1-13C]-Phe. Modifications in the isotope protocol should be made to achieve steady state of 13CO2 in breath, and thus, to successfully apply the IAAO technique to determine requirement of AA in adult cats.

European guideline on indications, performance, and clinical impact of hydrogen and methane breath tests in adult and pediatric patients: European Association for Gastroenterology, Endoscopy and Nutrition, European Society of Neurogastroenterology and Motility, and European Society for Paediatric Gastroenterology Hepatology and Nutrition consensus.

INTRODUCTION: Measurement of breath hydrogen (H2 ) and methane (CH4 ) excretion after ingestion of test-carbohydrates is used for different diagnostic purposes. There is a lack of standardization among centers performing these tests and this, together with recent technical developments and evidence from clinical studies, highlight the need for a European guideline. METHODS: This consensus-based clinical practice guideline defines the clinical indications, performance, and interpretation of H2 -CH4 -breath tests in adult and pediatric patients. A balance between scientific evidence and clinical experience was achieved by a Delphi consensus that involved 44 experts from 18 European countries. Eighty eight statements and recommendations were drafted based on a review of the literature. Consensus (≥80% agreement) was reached for 82. Quality of evidence was evaluated using validated criteria. RESULTS: The guideline incorporates new insights into the role of symptom assessment to diagnose carbohydrate (e.g., lactose) intolerances and recommends that breath tests for carbohydrate malabsorption require additional validated concurrent symptom evaluation to establish carbohydrate intolerance. Regarding the use of breath tests for the evaluation of oro-cecal transit time and suspected small bowel bacterial overgrowth, this guideline highlights confounding factors associated with the interpretation of H2 -CH4 -breath tests in these indications and recommends approaches to mitigate these issues. CONCLUSION: This clinical practice guideline should facilitate pan-European harmonization of diagnostic approaches to symptoms and disorders, which are very common in specialist and primary care gastroenterology practice, both in adult and pediatric patients. In addition, it identifies areas of future research needs to clarify diagnostic and therapeutic approaches.

Assessment of Breathomics Testing Using High-Pressure Photon Ionization Time-of-Flight Mass Spectrometry to Detect Esophageal Cancer.

Importance: A triage test is needed to increase the detection rate for esophageal cancer. Objective: To investigate whether breathomics can detect esophageal cancer among patients without a previous diagnosis of cancer using high-pressure photon ionization time-of-flight mass spectrometry (HPPI-TOFMS). Design, Setting, and Participants: This diagnostic study included participants who planned to receive an upper endoscopy or surgery of the esophagus at a single center in China. Exhaled breath was collected with a self-designed collector and air bags before participants underwent these procedures. Sample collection and analyses were performed by trained researchers following a standardized protocol. Participants were randomly divided into a discovery data set and a validation data set. Data were collected from December 2020 to March 2021. Exposures: Breath samples were analyzed by HPPI-TOFMS, and the support vector machine algorithm was used to construct a detection model. Main Outcomes and Measures: The accuracy of breathomics was measured by the sensitivity, specificity, accuracy, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve. Results: Exhaled breath samples were obtained from 675 patients (216 [32%] with esophageal cancer; 459 [68%] with noncancer diseases). Of all patients, 206 (31%) were women, and the mean (SD) age was 64.0 (11.9) years. In the validation data set, esophageal cancer was detected with an accuracy of 93.33%, sensitivity of 97.83%, specificity of 83.72%, positive predictive value of 94.74%, negative predictive value of 92.78%, and area under the receiver operating characteristic curve of 0.89. Notably, for 16 patients with high-grade intraepithelial neoplasia, 12 (75%) were predicted to have esophageal cancer. Conclusions and Relevance: In this diagnostic study, testing breathomics using HPPI-TOFMS was feasible for esophageal cancer detection and totally noninvasive, which could help to improve the diagnosis of esophageal cancer.

Volatile organic compounds (VOCs) in exhaled breath as a marker of hypoxia in multiple chemical sensitivity.

In the history of diagnostics, breath analysis was one of the first method used until the breakthrough of biochemical testing technology. Today, breath analysis has made a comeback with the development of gas analyzers and e-noses, demonstrating its power in its applicability for diagnosing a wide range of diseases. The physical basis of multiple chemical sensitivity (MCS), an emerging environmental disease, is difficult to understand because it is based on the scenario of chronic hypoxia, with a complex of chemical compounds that trigger the syndrome and result in multiple symptoms. The aim of this study was to investigate MCS by analyzing exhaled volatile organic compounds (VOCs). The volatile, metabolic picture could be a putative gold standard for understanding and diagnosing the disease. The study was based on recording in resting condition using the noninvasive passive e-nose contactless breath test, the Olfactory Real-Time Volatile Organic Compounds (ORT-VOC) test in MCS, and control samples. The VOCs profile distinguished between disease and health. It also distinguished the gender-related volatile profile with significant robustness. The results trace a putative compensatory physiological pathway elicited by increased lactate, leading to acidosis, and hyperventilation, resulting in the production of specific VOCs. We conclude that breath testing is a valuable tool to investigate the hypoxia-related VOC profile, facilitating MCS diagnosis.

Towards reliable diagnostics of prostate cancer via breath.

Early detection of cancer is a key ingredient for saving many lives. Unfortunately, cancers of the urogenital system are difficult to detect at early stage. The existing noninvasive diagnostics of prostate cancer (PCa) suffer from low accuracy (< 70%) even at advanced stages. In an attempt to improve the accuracy, a small breath study of 63 volunteers representing three groups: (1) of 19 healthy, (2) 28 with PCa, (3) with 8 kidney cancer (KC) and 8 bladder cancer (BC) was performed. Ultrabroadband mid-infrared Fourier absorption spectroscopy revealed eight spectral ranges (SRs) that differentiate the groups. The resulting accuracies of supervised analyses exceeded 95% for four SRs in distinguishing (1) vs (2), three for (1) vs (3) and four SRs for (1) vs (2) + (3). The SRs were then attributed to volatile metabolites. Their origin and involvement in urogenital carcinogenesis are discussed.

European guideline on indications, performance and clinical impact of 13 C-breath tests in adult and pediatric patients: An EAGEN, ESNM, and ESPGHAN consensus, supported by EPC.

INTRODUCTION: 13 C-breath tests are valuable, noninvasive diagnostic tests that can be widely applied for the assessment of gastroenterological symptoms and diseases. Currently, the potential of these tests is compromised by a lack of standardization regarding performance and interpretation among expert centers. METHODS: This consensus-based clinical practice guideline defines the clinical indications, performance, and interpretation of 13 C-breath tests in adult and pediatric patients. A balance between scientific evidence and clinical experience was achieved by a Delphi consensus that involved 43 experts from 18 European countries. Consensus on individual statements and recommendations was established if ≥ 80% of reviewers agreed and <10% disagreed. RESULTS: The guideline gives an overview over general methodology of 13 C-breath testing and provides recommendations for the use of 13 C-breath tests to diagnose Helicobacter pylori infection, measure gastric emptying time, and monitor pancreatic exocrine and liver function in adult and pediatric patients. Other potential applications of 13 C-breath testing are summarized briefly. The recommendations specifically detail when and how individual 13 C-breath tests should be performed including examples for well-established test protocols, patient preparation, and reporting of test results. CONCLUSION: This clinical practice guideline should improve pan-European harmonization of diagnostic approaches to symptoms and disorders, which are very common in specialist and primary care gastroenterology practice, both in adult and pediatric patients. In addition, this guideline identifies areas of future clinical research involving the use of 13 C-breath tests.

Abstinence from smoking and expired-air carbon monoxide levels: lactose intolerance as a possible source of error.

We investigated a possible source of contamination of expired-air carbon monoxide (CO) readings on CO monitors from raised expired-air hydrogen (H2) levels, namely lactose intolerance, the norm in certain ethnic groups. A significant correlation between expired-air CO and H2 readings was observed in four non-smoking lactose maldigesters.

The response of the Intoxilyzer 4011AS-A to a number of possible interfering substances.

Five Intoxilyzer 4011AS-As were tested for their response to eleven chemicals and one mixture of chemicals. The air/water partition ratios were also determined for these eleven chemicals and one mixture. The chemicals tested and their approximate partition ratios were the following: acetaldehyde (190:1), acetone (341:1), acetonitrile (578:1), isoprene (1:1), isopropanol (1671:1), methanol (3229:1), methylene chloride (11:1), methyl ethyl ketone (229:1), toluene (5.5:1), 1,1,1-trichloroethane (14:1), trichloroethylene (20:1), and a 50:50 mixture of 1,1,1-trichloroethane and trichloroethylene (14:1). Of the eleven chemicals and one mixture studied during this experiment, only three, isopropanol, toluene, and methyl ethyl ketone, could reasonably interfere with the test, and then only under unusual circumstances--those circumstances being a slight additive effect to a breath ethanol concentration near the level required for prosecution. Any substantial additive effect from these three substances would illuminate the interference light which invalidates the test. The mean illumination point of the interference light was 0.0286 g/210 L for methyl ethyl ketone, 0.0294 for toluene, and between 0.0116 and 0.0292 for the apparent alcohol concentration for isopropanol, depending on the amount of isopropanol metabolized to acetone. Even with these unusual circumstances considered, the Intoxilyzer 4011AS-A must be viewed as an effective way of determining the ethanol concentration in human breath for evidential purposes.

Local dental anaesthesia and evidential breath testing: the effect of injection of local anaesthetic on lip seal.

The effect of local anaesthetic infiltration on the ability of subjects to provide adequate specimens of breath for analysis using an evidential breath testing device was assessed. The results showed that in ten out of the fourteen cases there was no impairment of the ability to provide the specimens of breath at any time. Within two hours of the administration of a local anaesthetic all subjects were able to provide the requisite samples.

Accuracy and precision of breath alcohol measurements for subjects in the absorptive state.

Published data are analyzed in order to estimate the accuracy of breath-alcohol measurements for subjects during absorption of orally ingested ethanol. Simultaneous measurements of breath alcohol concentration (BrAC) and venous blood alcohol concentration (VBAC) show that actual VBAC can be overestimated by more than 100% for a significant amount of time after drinking stops. The maximum error found for four individual subjects is +230%, +190%, +60%, and +30%. The magnitude of these errors indicates that results from quantitative evidential breath alcohol analyzers are far less accurate for the absorptive state than they are during the postabsorptive state, but the specifications for accuracy and precision given by manufacturers of these instruments do not reflect this. The results also indicate that there is a significant likelihood that subjects will be in the absorptive state when tested under field conditions. I conclude that estimates of BAC based on BrAC measurements are not reliable in the absorptive state and that the uncertainty associated with such estimates should be accounted for, particularly when the results are used in connection with law enforcement.

Quality control aspects of expired air carbon monoxide measurement in the Multiple Risk Factor Intervention Trial.

The determination of carbon monoxide levels in the expired air of MRFIT participants was used to monitor the level of cigarette smoking in all participants and to assess the adherence of the SI participants to the MRFIT protocol, which required that they quit or reduce their cigarette smoking. Two problems affected the quality of the data. First, as with the measurements of pulmonary function (Chapter 12), the initial lack of training in adequate maintenance was responsible for inoperative instruments. Centralized training, both in the performance of the test and in equipment maintenance, helped to solve this problem. For future clinical trials, the importance of centralized training and certification of all technicians at the start of the study cannot be overemphasized. The second problem, the instability of the CO calibration gas in steel tanks over long periods, was not anticipated. The solution was to purchase small amounts of freshly prepared calibration gas, or to have such gas available to check the major gas supply. Many of the observed maintenance problems might have been avoided by the use of a checklist to ensure that preventive measures were taken before the equipment became inoperative.

Accuracy and usefulness of a breath alcohol analyzer.

We evaluated the accuracy of a hand-held breath alcohol analyzer in the rapid determination of blood alcohol levels in the emergency patient with suspected ethanol intoxication. The Alco -Sensor III breath alcohol analyzer was used to measure alcohol levels in orally and nasally obtained end-expiratory breath samples in 55 patients. These levels were compared to directly measured blood alcohol levels. The patients were categorized into cooperative and uncooperative groups. The mean oral breath alcohol level obtained was 0.187 +/- 0.100 g/dL (range, 0.000 to 0.419) while the mean serum level was 0.217 +/- 0.113 g/dL (range, 0.00 to 400). The overall correlation between these two methods of measuring blood alcohol level was strong (r = .879, P less than .001). In cooperative patients the correlation was even stronger (r = .963, P less than .001), while in uncooperative patients the correlation was less but still significant (r = .723, P = .001). Nasally obtained samples correlated well with blood levels in cooperative patients (r = .874, P less than .001), but the correlation was less strong in uncooperative persons (r = .694, P = .003). Our study indicates that the Alco -Sensor III breath alcohol analyzer is sufficiently accurate to be of use in rapidly assessing blood alcohol levels, even when a patient is unable to cooperate fully.

Validating reports of nonsmoking with breath and saliva samples: your checkup is in the mail.

Reports of nonsmoking are usually validated by obtaining breath carbon monoxide levels or saliva thiocyanate levels. However, it is often not convenient to obtain such samples from persons who participated in a smoking cessation program long in the past. Obtaining the samples through the mail could help solve this problem, but it is possible that the time the samples spend in the uncontrolled environment of the mails might invalidate the measured levels. The present study was to see whether that possibility was indeed a real concern. Breath and saliva samples were collected in airtight containers and allowed to remain in an uncontrolled environment (60 degrees-80 degrees F) for 72 hours, 24 hours, and less than one hour. The results suggest that the time spent in this environment had minimal impact on the carbon monoxide or thiocyanate levels in smokers' or nonsmokers' samples. Even after 72 hours, the samples could differentiate smokers from nonsmokers with little overlap. It appears that breath and saliva samples can be conveniently obtained through the mail without sacrificing their usefulness.

13C abundances of nutrients and the effect of variations in 13C isotopic abundances of test meals formulated for 13CO2 breath tests.

Unlike 14CO2 breath tests, 13CO2 breath tests are performed in the presence of a large background of naturally occurring isotope. Because the exact abundance of 13CO2 in breath can be changed by variations in diet, a study of the 13C abundance of dietary constituents and their effects on breath 13CO2 has been undertaken. Dietary constituents have been combusted to CO2 and the relative abundance of 13C analyzed by mass spectrometry. Breath CO2 was collected and isotopically analyzed after the ingestion of several dietary constituents and test meals. The 13CO2 abundance of breath CO2 was shown to change in response to the 13C abundance of the substrate being oxidized. Conversely, a test meal that closely approximates the 13C abundance of fasting breath CO2 from North Americans was shown not to alter the 13CO2 abundance in breath. Investigation of the breath 13CO2 response to individual 13C-labeled dietary constituents demonstrated that amino acids produced the earliest 13CO2 response followed in order by medium chain triglycerides, carbohydrates, and long chain triglycerides. Because of the variation in 13C abundances in nature, the 13C abundance of any unlabeled substrate ingested during a 13CO2 breath test must be considered in order to eliminate artifacts that may reduce the sensitivity of the breath test or produce erroneous results. Methods for correcting breath tests for changes in background 13CO2 abundance are also discussed.

[The mixing index in the argon breath holding test for the demonstration of pharmacologically induced airways reactions. A comparison with other methods (author's transl)]. / Der Mischungsindex in der Argon-Breath-Holding-Methode zur Objektivierung pharmakologisch ausgelöster Atemwegsreaktionen im Vergleich mit anderen Untersuchungsmethoden.

In 42 patients with obstructive airways diseases the behavior of the mixing index (delta argon %/1 during phase III of the argon-volume diagram) was studied after beta2 stimulation or after provocation by acetylcholine. Changes in airways resistance resp. conductance (GAW), FEV1.0 and residual volume (RV) were also determined for comparison. In an inhomogeneous subgroup with obstructive airways disease of various aetiology the mixing index (MI) and FEV1.0 indicated changes in the airways system with about equal frequency. Distinct discrepancies between the two tests, observed in a few cases, suggest that the two methods register different pathophysiological reactions. These differences could be confirmed statistically in a more homogeneous subgroup with extrinsic bronchial asthma. A correlation could be established between MI and RV on the one hand and between FEV1.0 or GAW and RV on the other hand. The results indicate that the mixing index as a test of distribution of ventilation reflects mainly the reactions of the small airways. Its use offers the possibility of a more differentiated pharmacodynamic evaluation.

Sensitivity of bile acid breath test in the diagnosis of bacterial overgrowth in the small intestine with and without the stagnant (blind) loop syndrome.

The bile acid breath test was studied to examine its sensitivity for establishing the diagnosis of bacterial overgrowth in comparison to that of the Schilling test and small-intestinal cultures in 12 patients with a stagnant (blind) loop syndrome, as well as in 38 patients who had other conditions with suspected bacterial contamination of the small intestine. The presence of bile acid malabsorption was excluded in all 50 patients by studies of fecal excretion of radioactively labeled bile acids. The bile acid breath test was positive in 100% (12/12) of the patients with a stagnant (blind) loop syndrome, whereas 92% (11/12) had a positive Schilling test and 75% (9/12) a positive small-intestinal culture. The abnormal tests improved only in 2 of 4 patients treated with tetracycline. In the group of 38 patients without demonstrable dilated or blind loops of small bowel who were suspected of having bacterial contamination of small bowel, the bile acid breath test was positive in 53% (20/38), the Schilling test in 39% (15/38), and the small-intestinal culture in 45% (17/38). The difference in the incidence of positive results between the tests in the two patient groups was statistically not significant. The findings of these studies have the following diagnostic implications: (1) Bile acid breath test, Schilling test, and cultures of aspirates from the upper small bowel are of comparable sensitivity in the detection of bacterial overgrowth in the small intestine. (2) A negative bile acid breath test makes the diagnosis of a stagnant (blind) loop syndrome very unlikely.