Fig. 6.

3-Methylhistidine is increased in Class 2 ARDS patients. a Relative amounts (peak area ratio of analyte/internal standard) of 3-methylhistidine shown were determined using stable isotope labeled liquid chromatography high resolution mass spectrometry. Controls are shown as black circles, Class 1 as blue squares, and Class 2 as red triangles with black bars representing medians. Group comparisons were performed using the Kruskal–Wallis test. Asterisks indicate P < 0.001 (***), P < 0.0001(****), and ns (not significant). b–e show Spearman correlation coefficients (ρ) for 3-methylhistidine with (b) acetylcarnitine, (c) creatinine, and log concentrations of (d) TNFR1 and (e) RAGE