Clinical data in subjects at all 3 time points (T0, T3, and T6) examined.

<p>All 14 subjects are included in the analysis of parameters related to body weight and lipids. Decreases after RYGB were observed for BMI, weight, fat mass, fat free mass, resting energy expenditure and triglycerides. Leptin was also decreased significantly. While HDL-cholesterol decreased from T0 to T3, HDL-Cholesterol levels recovered by T6 and are confirmed by the lack of change in Apo-A1 levels. Total caloric intake decreased after RYGB; however, the relative proportion of lipid, carbohydrate, and protein consumed remained stable. When considering the 12 subjects not treated with insulin, glucose and insulin levels decreased post RYGB. Estimates for HOMA-IR and HOMA%B decreased while HOMA%S increased after surgery. Data presented as mean±standard error. * represents p<0.1 and ** represents p<0.05, assessed by a Friedman test.</p

Increases in nervonic acid following RYGB.

<p>A significant increase in serum abundance of nervonic acid occurred following RYGB in both OB and OB/D subjects, as assessed using a mixed-effects ANOVA with group:time interaction (** <i>p</i><0.01 versus T0). Overall, nervonic acid levels were significantly different at each time point between OB and OB/D subgroups (p<0.01, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007905#pone-0007905-t002" target="_blank"><b>TABLE 2</b></a>). No group:time interaction was identified. Mean metabolite abundance±SEM is indicated in red.</p

Estimates for HOMA-IR before and after RYGB.

<p>HOMA-IR was estimated for 12 subjects, 9 OB and 3 OB/D subjects. The OB/D subjects were treated with metformin and not with insulin. A significant reduction (T0 → T3, p = 0.014; T0 → T6, p = 0.001; T3 → T6, p = 0.123) in HOMA-IR occurred following RYGB, as assessed using a Friedman test. Prior to RYGB, significant variability in HOMA-IR estimations was observed between subjects (because OB and OB/D subjects are combined); however, post RYGB, all subjects demonstrated a major improvement in insulin sensitivity (illustrated by smaller error bars). Box plots indicate no outlying data (i.e. above or below the whiskers), and the band in the middle of the box indicates the median. ** <i>p</i><0.01.</p

Increases in 1,5-anhydrosorbitol and decreases in ascorbic acid following RYGB.

<p>The top two metabolites distinguishing OB and OB/D subjects were identified with the mixed-effects ANOVA allowing for group:time-interactions, where * indicates <i>p</i><0.05 (versus T0). White circles and black circles correspond to OB/D or OB subjects, respectively. Furthermore, symbols and numbers are consistently used for the same subject in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007905#pone-0007905-g004" target="_blank">Figures 4</a> & <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007905#pone-0007905-g005" target="_blank">5</a>. Mean metabolite abundance±SEM is indicated in red. A) A significant increase in 1,5-anhydrosorbitol (1,5-AG) occurred at T6 vs. T0 in OB/D subjects, while a non-significant increase was seen in OB subjects (group:time interaction was allowed for by the linear model). B) For ascorbic acid, the ANOVA model did not detect group-specific changes over time (no group:time interaction), but indicated significant decreases from T0 to T6 in both groups. Overall, 1,5-anhydrosorbitol and ascorbic acid were significantly different at each time point between OB and OB/D subgroups (p<0.01, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007905#pone-0007905-t002" target="_blank"><b>TABLE 2</b></a>).</p

Various profiles for metabolites that change significantly at some point following RYGB.

<p>A profile is characterized by 3 dots, which represent T0 (prior to RYGB), T3 and T6 (post surgery). An angled slope between two time points indicates a significant change (p<0.05) and a flat slope between two time points indicates non-significant changes. Based on data derived from the mixed-effects ANOVA using all 14 subjects together. (*1): Structure annotation is based on strong analytical evidence (combinations of chromatography, mass spectrometry, chemical reactions, deuterium-labeling, database and literature search, as well as comparisons to similar/homologue/isomeric reference compounds). (*2): Metabolite exhibits identical qualitative analytical characteristics (chromatography and mass spectrometry) compared to status (*1). Further structural and analytical investigations of this metabolite - also in comparison to structurally identified or status (*1) metabolites - are still pending.</p

Metabolite lists differentiating OB from OB/D subjects at each time point.

<p>Metabolites were identified using a mixed-effects ANOVA: 33 metabolites at T0, 32 metabolites at T3, and 28 metabolites at T6 (p<0.05), with indication of whether serum levels are higher in obese (OB) or obese/diabetic (OB/D) subjects. Those metabolites present in all three lists are indicated in bold font. The profiles for metabolites whose abundance changed post surgery are found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007905#pone-0007905-g001" target="_blank"><b>FIGURE 1</b></a>. (*1): Structure annotation is based on strong analytical evidence (combinations of chromatography, mass spectrometry, chemical reactions, deuterium-labeling, database and literature search, as well as comparisons to similar/homologue/isomeric reference compounds). (*2): Metabolite exhibits identical qualitative analytical characteristics (chromatography and mass spectrometry) compared to status (*1). Further structural and analytical investigations of this metabolite - also in comparison to structurally identified or status (*1) metabolites - are still pending.</p