Figure 1.
MALDI positive mode imaging of skin tissue: (a) Nonmetric dimensional plot of the metabolites present in fresh frozen and FFPE samples. An ANOSIM test showed that there are significant differences in the metabolic profiles of the groups tested. (Stress: 0.03219174, ANOSIM statistic R: 1, significance: 1 × 10−4). (b) Heatmap plot of the top 50 most significantly different metabolites between the two groups. (c) Venn diagram showing the unique and shared metabolites from the two groups. (d–f) Metabolic pathway analysis plot created using MetaboAnalyst 5.0, USA. Plots depict several metabolic pathways that differ between the fresh frozen and FFPE samples tested. (d) Differential metabolites calculated from FFPE vs. fresh frozen samples. (e) Common metabolites from the FFPE and fresh frozen groups were sorted based on p-values (high to low). (f) Differential metabolites were calculated from fresh frozen vs. FFPE. (Box color corresponds to the same color from the Venn diagram). The y-axis is the log scale of the p-value; pathways that were most significantly different are characterized by high –log10(p) values. (g) The top 50 common metabolites were sorted based on p-value and are represented as a heatmap with their detected intensities. (h–j) Specific metabolite distribution images are presented along with an intensity box plot. (h) An image of type IV B antigen distribution in both tissues and an intensity box plot of the same metabolite’s distribution. (i) An image of NPA028417 distribution in both tissues and an intensity box plot of the same metabolite’s distribution. (j) An image of SM 20:3: 20/40 distribution in both tissues and an intensity box plot of the same metabolite’s distribution.