N-acetylaspartate as an intrinsic thermometer for 1H NMR of brain slices

Temperature dependence of 1H NMR chemical shifts and its influence on estimated metabolite concentrations

“…These changes are of the same magnitude as the average value of −6 × 10 −4 ppm/K measured for the established chemical shift reference tetramethylsilane (TMS) published by Hoffman et al [35]. It is noteworthy that the temperature dependence of the chemical shifts of amide protons is one magnitude stronger as reported by Baxter et al for proteins [33] and by Arus et al for NAA [32].…”

“…For all metabolites, the group of hydrogen atoms showing the smallest temperature dependence of its chemical shift with respect to the DSS signal (OneWay ANOVA for repeated measurements; Tukey post-test; GraphPad Prism 5.0, Inc., San Diego, CA, USA) was used as subtrahend. The relation between chemical shift and temperature was determined by linear regression [32,33].…”

“…Additional studies have only examined the influence of temperature on the 1 H chemical shifts of amide protons [32], proteins [33], and solvents used for reference signals [34][35][36]. Thus, the present study aims to determine the temperature dependence of 1 H chemical shifts of important brain metabolites and to investigate its influence on spectrum quantification if temperature induced changes in chemical shift values are not taken into consideration, i.e., if incorrect prior knowledge is used.…”

TISSUE METABOLISM STUDIED IN VIVO BY NUCLEAR MAGNETIC RESONANCE

“…Phosphocreatine resonates close to the creatine signals at 3 04, 3-96 and 6-9 p.p.m., but has an additional signal at 7-3 p.p.m. from aromatic moieties such as adenosine and nitrogen-linked protons from creatine, phosphocreatine and N-acetyl aspartate are also lost if a spin-echo is used (but see Arus et al (1984Arus et al ( , 1985b for spectra recorded without a spin-echo). The editing methods discussed above are essential if unequivocal detection in vivo of, for example, lactate, alanine or glutamate is to be possible.…”

“…The spectrum of the neutralized extract was recorded using the 1331 sequence at a field of 8-5 T. The assignments are as follows: 1, lactate; 2, alanine; 3, y-aminobutyrate; 4, acetate; 5, Nacetylaspartate; 6, glutamate + glutamine; 7, y-aminobutyrate; 8, glutamate; 9, glutamine; 10, N-acetylaspartate; 11, creatine; 12, choline, phosphorylcholine+glycerophosphorylcholine; 13, inositol+taurine; 14, taurine; 15, glycine; 16, inositol; 17, alanine, glutamate + glutamine; 18, creatine; 19, nucleotides + nucleosides; 20, creatine; 21, N-acetylaspartate. The assignments are based on the work of Behar et al (1983Behar et al ( , 1985, Arus et al (1985b), and Cerdan, Parrilla, Santoro & Rico (1985). B, 'H n.m.r.…”