Overview of alterations in glucose metabolism in the IDH1 mutated and IDH1 wild-type gliomas relative to glucose metabolism in normal brain. The enzymes included in the analysis are shown in black. The bar diagrams show the averaged expressional levels of genes that were significantly differently expressed in the IDH1 mutated gliomas (n = 33, blue bars on the left); IDH1 wild-type (n = 39, red bars in the middle); and normal brain (n = 4, green bars on the right). Glycolysis leads to the production of pyruvate. In normal brain, pyruvate is converted to acetyl-CoA, which enters the TCA cycle in the mitochondria. But in the IDH1 wild-type tumors, pyruvate is metabolized to lactate (“the Warburg effect” in which the aerobic glycolysis serves as a quick energy source that results in tissue acidosis). To ensure the origin and quality of the tissues, all tissues were assessed by a qualified pathologist before isolation. IDH1 status was checked using IHC and the standard PCR test. Total RNA was isolated with the RNA-Bee (Campro, Veenendaal, The Netherlands). cDNA was prepared using the RevertAid H Minus First Strand cDNA synthesis kit (Fermentas, St Leon-Rot, Germany). The resulting cDNA preparations were analysed by real-time PCR with SYPR green master mix solution (Applied Biosystems, Nieuwerkerk a/d IJssel, The Netherlands). PCRs were performed in a 25 μL reaction volume in an Applied BioSystems 7900HT Fast Real-Time PCR system. Negative controls included minus RT and H2O-only samples, which were negative in all cases. Expression of B2M, HPRT1 and PBGD was used as a reference to control sample loading and RNA quality. Differences in mRNA concentrations were determined using the t- test, with P < 0.01 being considered statistically significant. All statistical tests were two-sided.