Functional activation of pyruvate dehydrogenase in human brain using hyperpolarized [1- C]pyruvate.

Purpose: Pyruvate, produced from either glucose, glycogen, or lactate, is the dominant precursor of cerebral oxidative metabolism. Pyruvate dehydrogenase (PDH) flux is a direct measure of cerebral mitochondrial function and metabolism. Detection of [ C]bicarbonate in the brain from hyperpolarized [1- C]pyruvate using carbon-13 ( C) MRI provides a unique opportunity for assessing PDH flux in vivo.

Glycine by MR spectroscopy is an imaging biomarker of glioma aggressiveness.

Background: High-grade gliomas likely remodel the metabolic machinery to meet the increased demands for amino acids and nucleotides during rapid cell proliferation. Glycine, a non-essential amino acid and intermediate of nucleotide biosynthesis, may increase with proliferation. Non-invasive measurement of glycine by magnetic resonance spectroscopy (MRS) was evaluated as an imaging biomarker for assessment of tumor aggressiveness.

3D high-resolution imaging of 2-hydroxyglutarate in glioma patients using DRAG-EPSI at 3T in vivo.

Purpose: To develop 3D high-resolution imaging of 2-hydroxyglutarate (2HG) at 3T in vivo.

Methods: Echo-planar spectroscopic imaging with dual-readout alternated-gradients (DRAG-EPSI), which was recently reported for 2D imaging of 2HG at 7T, was tested for 3D imaging of 2HG at 3T. The frequency drifts and acoustic noise induced by DRAG-EPSI were investigated in comparison with conventional EPSI.

Echo-planar spectroscopic imaging with dual-readout alternated gradients (DRAG-EPSI) at 7 T: Application for 2-hydroxyglutarate imaging in glioma patients.

Purpose: To develop echo-planar spectroscopic imaging (EPSI) with large spectral width and accomplish high-resolution imaging of 2-hydroxyglutarate (2HG) at 7 T.

Methods: We designed a new EPSI readout scheme at 7 T. Data were recorded with dual-readout alternated gradients and combined according to the gradient polarity.

Measurement of glycine in healthy and tumorous brain by triple-refocusing MRS at 3 T in vivo.

Glycine (Gly) has been implicated in several neurological disorders, including malignant brain tumors. The precise measurement of Gly is challenging largely as a result of the spectral overlap with myo-inositol (mI). We report a new triple-refocusing sequence for the reliable co-detection of Gly and mI at 3 T and for the evaluation of Gly in healthy and tumorous brain.

Influence of liver triglycerides on suppression of glucose production by insulin in men.

Context: The ability of insulin to suppress hepatic glucose production is impaired among subjects with increased intrahepatic triglycerides (IHTG). However, little is known about the roles of insulin on the supporting fluxes of glucose production among patients with fatty liver.

Objective: To evaluate the effects of insulin on fluxes through the three potential sources of plasma glucose (glycerol, the citric acid cycle, and glycogen) among patients with fatty liver.

The effect of short-term fasting on liver and skeletal muscle lipid, glucose, and energy metabolism in healthy women and men.

Fasting promotes triglyceride (TG) accumulation in lean tissues of some animals, but the effect in humans is unknown. Additionally, fasting lipolysis is sexually dimorphic in humans, suggesting that lean tissue TG accumulation and metabolism may differ between women and men. This study investigated lean tissue TG content and metabolism in women and men during extended fasting.