title: Determination of endogenous methane formation by photoacoustic spectroscopy.
abstract: Aerobic methane generation was demonstrated earlier in plants and eukaryotes under various stress conditions. Our aims were to develop a real-time and noninvasive detection system for monitoring the methane production of small animals and humans with our without exposure to various treatments. A near-infrared diode laser technique was employed with photoacoustic spectroscopy to monitor a methane-containing atmosphere online. The whole-body methane generation of anesthetized mice and rats was determined under baseline conditions and following reduction of the intestinal methanogenic flora or after lipopolysaccharide administration. Single-breath methane analyses were also carried out in a cross-sectional clinical study in order to obtain comparative human data. The whole-body methane production of mice was significantly decreased after antibiotic treatment (M: 1.71 ppm cm(-2) 10(3); p25: 1.5 ppm cm(-2) 10(3); p75: 2.11 ppm cm(-2) 10(3)) and increased significantly in endotoxemia (M: 4.53 ppm cm(-2) 10(3); p25: 4.37 ppm cm(-2) 10(3); p75: 5.38 ppm cm(-2) 10(3)), while no difference was observed between the rat groups. The methane content of the exhaled breath in humans was found to be between 0 and 37 ppm. Photoacoustic spectroscopy is a reliable tool with which to monitor the in vivo dynamics of stress-induced methane production in laboratory animals, even in a very low concentration range.
authors.affiliation: Institute of Surgical Research, Faculty of Medicine, University of Szeged, Szeged, Hungary.
authors.forename: E
authors.initials: E
authors.lastname: Tuboly
authors.forename: A
authors.initials: A
authors.lastname: Szabó
authors.forename: G
authors.initials: G
authors.lastname: Erős
authors.forename: A
authors.initials: A
authors.lastname: Mohácsi
authors.forename: G
authors.initials: G
authors.lastname: Szabó
authors.forename: R
authors.initials: R
authors.lastname: Tengölics
authors.forename: G
authors.initials: G
authors.lastname: Rákhely
authors.forename: M
authors.initials: M
authors.lastname: Boros
mesh_terms: D000818:Animals; D001944:Breath Tests / Q000379:methods*; D002849:Chromatography, Gas; D003430:Cross-Sectional Studies; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D008297:Male; D008697:Methane / Q000032:analysis* / Q000096:biosynthesis*; D051379:Mice; D008812:Mice, Hairless; D061088:Photoacoustic Techniques / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012140:Respiratory Tract Diseases / Q000175:diagnosis / Q000378:metabolism*; D013057:Spectrum Analysis / Q000379:methods*; D055815:Young Adult
chemical_list: D008697:Methane