H OH metabolites OH Article The Importance of Objective Stool Classification in Fecal 1H-NMR Metabolomics: Exponential Increase in Stool Crosslinking Is Mirrored in Systemic Inflammation and Associated to Fecal Acetate and Methionine Leon Deutsch 1 and Blaz Stres 1,2,3,4,* 1 Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia;
[email protected] 2 Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jamova 2, SI-1000 Ljubljana, Slovenia 3 Department of Automation, Jožef Stefan Institute, Biocybernetics and Robotics, Jamova 39, SI-1000 Ljubljana, Slovenia 4 Department of Microbiology, University of Innsbruck, Technikerstrasse 25d, A-6020 Innsbruck, Austria * Correspondence:
[email protected]; Tel.: +386-41-567-633 Abstract: Past studies strongly connected stool consistency—as measured by Bristol Stool Scale (BSS)—with microbial gene richness and intestinal inflammation, colonic transit time and metabolome characteristics that are of clinical relevance in numerous gastro intestinal conditions. While retention time, defecation rate, BSS but not water activity have been shown to account for BSS-associated Citation: Deutsch, L.; Stres, B. The inflammatory effects, the potential correlation with the strength of a gel in the context of intestinal Importance of Objective Stool forces, abrasion, mucus imprinting, fecal pore clogging remains unexplored as a shaping factor for Classification in Fecal 1H-NMR intestinal inflammation and has yet to be determined. Our study introduced a minimal pressure ap- Metabolomics: Exponential Increase proach (MP) by probe indentation as measure of stool material crosslinking in fecal samples. Results in Stool Crosslinking Is Mirrored in reported here were obtained from 170 samples collected in two independent projects, including males Systemic Inflammation and and females, covering a wide span of moisture contents and BSS.