Search results for "Organic Compounds"
showing 10 items of 271 documents
Associations of diet and lifestyle factors with common volatile organic compounds in exhaled breath of average-risk individuals.
2018
Background Detection of diseases via exhaled breath remains an attractive idea despite persisting gaps in understanding the origin of volatile organic compounds (VOCs) and their relationship with the disease of interest. Data on factors potentially influencing the results of breath analysis remain rather sparse and often controversial. In this study, we aimed to investigate the associations of common VOCs in exhaled breath of average-risk individuals with socio-demographic and lifestyle factors, medical conditions as well as diet. Methods Alveolar breath samples of 1447 men and women were collected in the morning after fasting and were analyzed using gas-chromatography linked with mass-spec…
Ex vivo emission of volatile organic compounds from gastric cancer and non-cancerous tissue
2018
The presence of certain volatile organic compounds (VOCs) in the breath of patients with gastric cancer has been reported by a number of research groups; however, the source of these compounds remains controversial. Comparison of VOCs emitted from gastric cancer tissue to those emitted from non-cancerous tissue would help in understanding which of the VOCs are associated with gastric cancer and provide a deeper knowledge on their generation. Gas chromatography with mass spectrometric detection (GC-MS) coupled with head-space needle trap extraction (HS-NTE) as the pre-concentration technique, was used to identify and quantify VOCs released by gastric cancer and non-cancerous tissue samples c…
Geographical variation in the exhaled volatile organic compounds.
2013
Breath-gas analysis has demonstrated that concentration profiles of volatile organic compounds (VOCs) could be used for detecting a variety of diseases, among them gastric cancer (GC) and peptic ulcer disease (PUD). Here, we explore how geographical variation affects the disease-specific changes in the chemical composition of breath samples, as compared to control states (less severe gastric conditions). Alveolar exhaled breath samples from 260 patients were collected at two remotely different geographic locations (China and Latvia), following similar breath-collection protocols. Each cohort included 130 patients that were matched in terms of diagnosis (37 GC/32 PUD/61 controls), average ag…
Real time analysis of volatile organic compounds (VOCs) in centenarians.
2014
Centenarians are a model to study human longevity and the physiological process of aging. A plethora of studies on this model show the complexity of the system. Laboratory studies fail to find a biomarker of senescence. The real time exhaled breath volatile organic compounds (VOCs) has been suggested as a new biomarker to detect and monitor physiological processes in the respiratory system. VOCs exhaled by centenarians have not been studied in the general population and across-age-groups. In the present study we investigated, in real time, the breath properties and VOC exhaled content in healthy centenarians as compared with non-centenarian seniors and young healthy subjects. We found disti…
Analysis of the effects of microbiome-related confounding factors on the reproducibility of the volatolomic test.
2016
Volatile organic compound (VOC) testing in breath has potential in gastric cancer (GC) detection. Our objective was to assess the reproducibility of VOCs in GC, and the effects of conditions modifying gut microbiome on the test results. Ten patients with GC were sampled for VOC over three consecutive days; 17 patients were sampled before and after H. pylori eradication therapy combined with a yeast probiotic; 61 patients were sampled before and after bowel cleansing (interventions affecting the microbiome). The samples were analyzed by: (1) gas chromatography linked to mass spectrometry (GC-MS), applying the non-parametric Wilcoxon test (level of significance p 0.05); (2) by cross-reacti…
Pathologies currently identified by exhaled biomarkers.
2013
Ancient Greek physicians already knew that the smell of human breath could provide a clue to the pathology. Nowadays, volatile breath biomarkers are known to be released in a broad range of diseases. However, their identification, isolation, and quantification as indicative of relevant alterations in clinical status have required the development of new techniques and analytical methods. Breath sample analysis encounters several obstacles. Particularly, there is a need of a system that could work in a continuous manner, with the low concentration and small volume of a sample. Herein we review, in the light of literature and our experience, clinical applications of the metal oxide semiconduct…
A theoretical study of the low-lying excited states of thieno[3,4-b]pyrazine
2009
The low-lying electronic excited states of thieno[3,4-b]pyrazine have been studied using the multiconfigurational second-order perturbation CASPT2 theory with extended atomic natural orbital basis sets. The CASPT2 results allow for a full interpretation of the electronic absorption and emission spectra and provide valuable information for the rationalization of the experimental data. The nature, position, and intensity of the spectral bands have been analyzed in detail. A preliminary comparative study of the ground-state geometry of thieno[3,4-b]pyrazine has been performed at the coupled cluster single and doubles and density functional theory levels using a variety of correlation-consisten…
An unusually high substitution rate in transplant-associated BK polyomavirus in vivo is further concentrated in HLA-C-bound viral peptides
2018
Infection with human BK polyomavirus, a small double-stranded DNA virus, potentially results in severe complications in immunocompromised patients. Here, we describe the in vivo variability and evolution of the BK polyomavirus by deep sequencing. Our data reveal the highest genomic evolutionary rate described in double-stranded DNA viruses, i.e., 10−3–10−5 substitutions per nucleotide site per year. High mutation rates in viruses allow their escape from immune surveillance and adaptation to new hosts. By combining mutational landscapes across viral genomes with in silico prediction of viral peptides, we demonstrate the presence of significantly more coding substitutions within predicted cog…
Crystal structure determination of 1-pentanol from low-temperature powder diffraction data by Patterson search methods
2005
5 pages.-- PACS: 61.66.Hq; 61.50.Lt
Electrochemical characterization of mangrove sediments: A proposal of new proxies for organic matter oxidation
2019
Abstract The voltammetric response of microparticulate deposits resulting from solvent evaporation of ethanolic extracts of mangrove sediments in contact with aqueous acetate buffer is hereby described. Dated sediment cores sampled from the Peruvian mangrove system (“Manglares de Tumbes” National Sanctuary) presented voltammetric responses dominated by oxidative signals of organic components that exhibit significant variations depending on the depth. Voltammetric data allowed for the definition of electrochemical indexes representative of the electrochemically oxidable organic matter fraction. These electrochemical indexes were fEAOM (for the total amount of organic matter being electrochem…