Representative ¹H-NMR spectrum of a VH sample with main resonance assignments.

<p>Representative ¹H-NMR spectrum of a VH sample with main resonance assignments.</p

Variables with VIP >1 and the corresponding regression coefficients for each VH area as calculated by PLS-DA.

<p>Higher regression coefficient values indicate higher comparative levels of the corresponding metabolite in the VH area. Attribution of variables to specific metabolites is also reported.</p><p>*Cho (Choline), PCho (Phosphocholine), GPCho (Glycerophosphocholine); ^†BCAA (Branched Chain Amino Acids).</p

PCA score plots of ¹H-NMR VH sample spectral data.

<p>A) PC1 vs. PC2; B) PC2 vs. PC3. The explained variance is reported in brackets. Numbers represent eye samples, letters represent topographic areas, and W stands for the entire VH (A green circles; B blue squares; C red up-pointing triangles; D yellow down-pointing triangles, W light blue diamonds). Ellipse indicates the 95% Hotelling T² confidence region. Samples with the same number and letter are duplicates.</p

HCA of sample distribution in the PC2 vs. PC3 score space. A tree sorted by Ward clustering.

<p>The vertical axis reports sample distances.</p

Demographic and clinical characteristics of subjects.

<p>Demographic and clinical characteristics of subjects.</p

OPLS-DA score plots in the predictive (<i>x</i>-axis) and orthogonal (<i>y</i>-axis) components of ¹H NMR spectral data of urine samples.

<p><b>A) “Pain <i>vs</i>. C” model. B) “NP <i>vs</i>. C” model. C) “NC <i>vs</i>. C” model. D) “NP <i>vs</i>. NC” model.</b> Separation of classes is maximized along the predictive component, while the orthogonal component accounts for intra-class variability. Ellipse indicates the confidence region. Pain: neuropathic and nociceptive pain samples—inverted grey triangles; C: matched control samples—green circles; NP: neuropathic pain samples—red squares; NC nociceptive pain samples—blue triangles. Details of OPLS-DA models performance are given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150476#pone.0150476.s003" target="_blank">S1 Table</a>.</p

Results of samples classification for the different two-classes discriminant models.

<p>Results of samples classification for the different two-classes discriminant models.</p