Figure 4a:

¹³C spectra from frontal brain of OTCD patient. After infusion of [2-¹³C]–glucose, ¹³C-enriched cerebral metabolites were assayed in posterior brain with low-power noise decoupling. ¹³C MR spectra were then acquired from frontal brain for further 40 minutes. (a) Glucose C2 (Glc2), with β and α anomers, was detected as four rather than two resonances and (b) metabolic products, glutamate C5 (Glu5), glutamine C5 (Gln5), bicarbonate (HCO3), and aspartate C2 (Asp2), were identified. Asp1 = aspartate C1, Gln1 = glutamine C1, Glu1 = glutamate C1. Inset: Sagittal image shows frontal brain region included in MR spectroscopic field of view (ellipse).