Venous fasting blood samples were collected in serum-tubes with no additives. The serum samples were stored at − 80 °C, until the time of metabolic profiling. The serum samples were slowly thawed at 4 °C. Aliquots of 150 μL were mixed with equal amounts of buffer solution and transferred to high-quality 3 mm MR tubes as described elsewhere [30 (link)].
The MR spectra were acquired using a Bruker Avance III 600 MHz/54 mm US-Plus (Bruker Biospin, Rheinstetten, Germany) operating at 600 MHz for proton (1H), equipped with a QCI cryoprobe. All spectra were recorded in an automatic fashion using a Bruker SampleJet and the ICON-NMR software (Bruker Biospin). Proton spectra were obtained at a constant temperature of 310 K (37 °C) using [1 (link)] a standard nuclear overhauser effect spectroscopy (NOESY) pulse sequence (Bruker: noesygppr1d) and [2 (link)] a Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence with presaturation during the relaxation delay (Bruker: cpmgpr1d) to achieve water suppression, and to facilitate the detection of low-molecular-weight species by avoiding the large overlapped signals derived from large molecules, such as proteins and lipids. Measurement and processing were done in full automation using Bruker standard automation programs controlled by ICON-NMR (along with TopSpin). Chemical shift was calibrated to the middle of the alanine peaks at 1.50 ppm.
The MR spectra were acquired using a Bruker Avance III 600 MHz/54 mm US-Plus (Bruker Biospin, Rheinstetten, Germany) operating at 600 MHz for proton (1H), equipped with a QCI cryoprobe. All spectra were recorded in an automatic fashion using a Bruker SampleJet and the ICON-NMR software (Bruker Biospin). Proton spectra were obtained at a constant temperature of 310 K (37 °C) using [1 (link)] a standard nuclear overhauser effect spectroscopy (NOESY) pulse sequence (Bruker: noesygppr1d) and [2 (link)] a Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence with presaturation during the relaxation delay (Bruker: cpmgpr1d) to achieve water suppression, and to facilitate the detection of low-molecular-weight species by avoiding the large overlapped signals derived from large molecules, such as proteins and lipids. Measurement and processing were done in full automation using Bruker standard automation programs controlled by ICON-NMR (along with TopSpin). Chemical shift was calibrated to the middle of the alanine peaks at 1.50 ppm.
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