Andrea Princivalle

Mercapturic acids in the biological monitoring of occupational exposure to chemicals.

This paper reviews several procedures for determination of mercapturic acids in urine. Special attention was paid to methods useful in relation to human exposure to industrial pollutants, without any description for less sensitive methods used in animal research. Gas chromatographic and liquid chromatographic procedures were considered together with the little information available about thin layer chromatography and immunochemical techniques. After a description of the main industrial pollutants which lead to synthesis of their specific mercapturic acids, the methods for analysing these products are synthetically reported. The comparison among difficulties in sample preparation, complexity of instrumentation and their cost/benefit ratio are discussed.

S-(acetamidomethyl)mercapturic acid (AMMA): A new biomarker for occupational exposure to N,N-dimethylacetamide

N,N-dimethylacetamide (DMA) is used in the textile and plastics industry as a solvent alternative to more toxic N,N-dimethylformamide. Here we studied toxicokinetics of two major urinary metabolites of DMA, namely, S-(acetamidomethyl)mercapturic acid (AMMA) and N-methylacetamide (NMA). Urine samples were collected from workers exposed to DMA in a factory manufacturing acrylic fibers. AMMA and NMA were determined by HPLC/MS and GC/MS, respectively. The working scheme in the factory consisted of periods of three consecutive working shifts alternated regularly with two days off work. In the first stage of the study, NMA and AMMA were determined in urine samples collected before, in the middle, and at the end of one working shift. In the second stage, urine was collected five times during three consecutive days after a two-day rest: before and at the end of the first and second working shifts and before the third shift. It was found that the end-of-shift NMA levels were several folds higher than the pre-shift levels of the same day and dropped significantly until the next shift. On the other hand, there were no significant differences in AMMA levels before and at the end of the same shift but a continuous rise during the three-day working period was observed. Median values of NMA concentrations at the end of working shifts were between 10.1 and 17.3 mg/g creatinine, median AMMA concentrations in the second or third day of the working period varied between 12.4 and 38.1 mg/g creatinine. The approximate half-lives of NMA and AMMA (means) in the exposed workers were about 9 and 29 h, respectively. Thus, while NMA in the end-of-shift urine samples remains a preferential biomarker of DMA exposure during that shift, AMMA determined at the end of a work-week reflects cumulative exposure over the last few days. Further studies are needed to determine AMMA concentrations corresponding to the threshold limit value of DMA.

Inflammatory bowel disease and patterns of volatile organic compounds in the exhaled breath of children: A case-control study using Ion Molecule Reaction-Mass Spectrometry

Inflammatory bowel diseases (IBD) profoundly affect quality of life and have been gradually increasing in incidence, prevalence and severity in many areas of the world, and in children in particular. Patients with suspected IBD require careful history and clinical examination, while definitive diagnosis relies on endoscopic and histological findings. The aim of the present study was to investigate whether the alveolar air of pediatric patients with IBD presents a specific volatile organic compounds’ (VOCs) pattern when compared to controls. Patients 10–17 years of age, were divided into four groups: Crohn’s disease (CD), ulcerative colitis (UC), controls with gastrointestinal symptomatology, and surgical controls with no evidence of gastrointestinal problems. Alveolar breath was analyzed by ion molecule reaction mass spectrometry. Four models were built starting from 81 molecules plus the age of subjects as independent variables, adopting a penalizing LASSO logistic regression approach: 1) IBDs vs. controls, finally based on 18 VOCs plus age (sensitivity = 95%, specificity = 69%, AUC = 0.925); 2) CD vs. UC, finally based on 13 VOCs plus age (sensitivity = 94%, specificity = 76%, AUC = 0.934); 3) IBDs vs. gastroenterological controls, finally based on 15 VOCs plus age (sensitivity = 94%, specificity = 65%, AUC = 0.918); 4) IBDs vs. controls, built starting from the 21 directly or indirectly calibrated molecules only, and finally based on 12 VOCs plus age (sensitivity = 94%, specificity = 71%, AUC = 0.888). The molecules identified by the models were carefully studied in relation to the concerned outcomes. This study, with the creation of models based on VOCs profiles, precise instrumentation and advanced statistical methods, can contribute to the development of new non–invasive, fast and relatively inexpensive diagnostic tools, with high sensitivity and specificity. It also represents a crucial step towards gaining further insights on the etiology of IBD through the analysis of specific molecules which are the expression of the particular metabolism that characterizes these patients.

Pancreatic ductal adenocarcinoma can be detected by analysis of volatile organic compounds (VOCs) in alveolar air

BackgroundIn the last decade many studies showed that the exhaled breath of subjects suffering from several pathological conditions has a peculiar volatile organic compound (VOC) profile. The objective of the present work was to analyse the VOCs in alveolar air to build a diagnostic tool able to identify the presence of pancreatic ductal adenocarcinoma in patients with histologically confirmed disease.MethodsThe concentration of 92 compounds was measured in the end-tidal breath of 65 cases and 102 controls. VOCs were measured with an ion-molecule reaction mass spectrometry. To distinguish between subjects with pancreatic adenocarcinomas and controls, an iterated Least Absolute Shrinkage and Selection Operator multivariate Logistic Regression model was elaborated.ResultsThe final predictive model, based on 10 VOCs, significantly and independently associated with the outcome had a sensitivity and specificity of 100 and 84% respectively, and an area under the ROC curve of 0.99. For further validation, the model was run on 50 other subjects: 24 cases and 26 controls; 23 patients with histological diagnosis of pancreatic adenocarcinomas and 25 controls were correctly identified by the model.ConclusionsPancreatic cancer is able to alter the concentration of some molecules in the blood and hence of VOCs in the alveolar air in equilibrium. The detection and statistical rendering of alveolar VOC composition can be useful for the clinical diagnostic approach of pancreatic neoplasms with excellent sensitivity and specificity.

A New Method to Detect Pancreatic Ductal Adenocarcinoma by Analysis of Volatile Organic Compounds (VOCs) in Alveolar Air

Context Early diagnosis of pancreatic ductal adenocarcinoma (PDA) is still a challenge. In the last decade many studies showed that the air exhaled by subjects suffering from lung and breast tumor shows peculiar profiles of volatile organic compounds (VOCs). The possible causal factors of PDA are able to alter the concentration of some VOCs in the alveolar air which can be collected with an easy-to-use, cheap and reliable device. Objective To determine a VOCs profile in the alveolar air able to discriminate patients suffering from PDA. Methods Air samples were obtained from patients affected by PDA cyto-histologically confirmed admitted in the Surgical Unit B of Verona University Hospital (Study Group). Patients characteristics, clinical and biohumoral data, surgical procedures and histological specimen reports were prospectively collected. The same air samples were collected from healthy subjects (Control Group) and in the environmental air of the rooms where the subjects studied were staying. Air samples were analysed by an ion molecule reaction-mass spectrometry analysis (IMR-MS). Through principal components analysis and multivariate logistic regression, a predictive model was created to distinguish subjects with PDA from control subjects. Results The concentration of 92 compounds among VOCs and gases (CO 2 and O 2 included) was measured in 75 patients end-tidal breath and in 144 control subjects. The predictive model was built on 65 cases and 102 controls with ages between 40 and 75 years and was based on 10 VOCs significantly and independently associated with the outcome, showing sensitivity and specificity values of 98.67% and 95.10%, respectively and an area under the ROC curve of 0.9887. Conclusion Using a profile of some VOCs we identify an algorithm able to discriminate subjects with pancreatic adenocarcinoma from control subjects with the best sensitivity and specificity ever reported by a single test. The test is cheap, non invasive and reproducible. We believe that it could be applied extensively and it could represent a screening test in high risk population for pancreatic ductal adenocarcinoma.