Comparison of amino-acid metabolomic profile in patients with the lowest (Q1) and highest (Q4) quartiles of computed tomography emphysema
| Q1 LAA <7.5% | Q4 LAA ≥25% | p-value | |
| Subjects n | 15 | 32 | |
| 1-Methylhistidine | 0.25 (0.04–0.89) | 0.81 (0.60–1.03) | 0.021 |
| 3-Methylhistidine | 0.14 (0.07–0.93) | 0.62 (0.23–1.68) | 0.100 |
| 4-Hydroxyproline | 44.0 (43.8–44.4) | 11.7 (11.4–12.5) | <0.001 |
| Aminoadipic acid | 1.39 (1.05–1.58) | 1.19 (0.93–1.37) | 0.045 |
| α-Aminobutyric acid | 1.55 (1.16–1.71) | 1.11 (0.87–1.31) | 0.008 |
| Alanine | 1.17 (0.92–1.35) | 0.95 (0.75–1.18) | 0.164 |
| Arginine | 0.78 (0.65–0.84) | 0.87 (0.74–0.94) | 0.013 |
| Asparagine | 4.1 (4.0–4.2) | 2.5 (2.4–2.6) | <0.001 |
| Aspartic acid | 1.42 (1.11–1.58) | 1.22 (0.91–1.61) | 0.264 |
| β-Aminoisobutyric acid | 0.77 (0.63–1.44) | 1.04 (0.79–1.33) | 0.538 |
| Citrulline | 1.43 (1.17–1.62) | 1.28 (1.11–1.54) | 0.451 |
| Cystathionine | 1.09 (0.61–1.26) | 1.03 (0.41–1.37) | 0.767 |
| Cystine | 1.80 (1.66–2.16) | 1.49 (1.40–1.71) | 0.004 |
| γ-Aminobutyric acid | 1.04 (0.86–1.25) | 1.27 (1.00–1.52) | 0.132 |
| Glutamic acid | 1.25 (1.19–1.50) | 1.08 (0.84–1.28) | 0.032 |
| Glutamine | 1.27 (1.16–1.43) | 1.19 (1.13–1.29) | 0.079 |
| Glycine | 3.5 (3.2–3.6) | 1.7 (1.5–1.9) | <0.001 |
| Glycine-proline | 12.2 (12.0–12.6) | 6.7 (6.1–7.3) | <0.001 |
| Histidine | 1.11 (0.94–1.21) | 1.07 (0.91–1.14) | 0.479 |
| Isoleucine | 1.20 (1.11–1.33) | 1.11 (0.90–1.34) | 0.087 |
| Leucine | 1.20 (1.08–1.40) | 1.09 (0.88–1.39) | 0.126 |
| Lysine | 0.85 (0.81–0.95) | 0.92 (0.86–1.03) | 0.349 |
| Methionine | 1.90 (1.55–2.33) | 2.38 (2.03–2.83) | 0.071 |
| Ornithine | 0.63 (0.32–0.74) | 0.69 (0.55–0.78) | 0.087 |
| Phenylalanine | 1.36 (1.31–1.45) | 1.21 (1.07–1.34) | <0.001 |
| Proline | 0.98 (0.85–1.13) | 0.95 (0.84–1.08) | 0.616 |
| Sarcosine | 80.5 (80.3–80.7) | 47.3 (47.1–47.8) | <0.001 |
| Serine | 0.46 (0.39–0.57) | 0.67 (0.45–0.83) | 0.005 |
| Thiaproline | 326 (322–330) | 172 (169–173) | <0.001 |
| Threonine | 0.44 (0.22–0.67) | 0.79 (0.53–1.01) | 0.023 |
| Tryptophan | 4.5 (4.3–4.8) | 2.9 (2.4–3.4) | <0.001 |
| Tyrosine | 1.11 (1.04–1.19) | 1.04 (0.94–1.18) | 0.273 |
| Valine | 0.81 (0.03–0.88) | 0.88 (0.71–1.04) | 0.220 |
Data are presented as median (interquartile range), unless otherwise stated. LAA: low attenuation area. Note: all subjects in this subset were male and were not current smokers. Bold font highlights significant differences between groups.