Correlated cryo-SEM and CryoNanoSIMS imaging of biological tissue.

Background: The development of nanoscale secondary ion mass spectrometry (NanoSIMS) has revolutionized the study of biological tissues by enabling, e.g., the visualization and quantification of metabolic processes at subcellular length scales.

Photochemistry of pyruvic acid is governed by photo-induced intermolecular electron transfer through hydrogen bonds.

Despite more than 85 years of research, the mechanism behind the photodecarboxylation of pyruvic acid remains elusive. Most studies focused on the gas and liquid phase of diluted solutions of pyruvic acid to understand the impact of sun light on the degradation of this molecule in the atmosphere. By analyzing concentrated supercooled solutions at 77 K, we demonstrate that instead of decarboxylating, the pyruvic acid molecule plays the role of electron donor and transfers an electron to an acceptor molecule that subsequently degrades to form CO.

[C]bicarbonate labelled from hyperpolarized [1-C]pyruvate is an in vivo marker of hepatic gluconeogenesis in fasted state.

Hyperpolarized [1-C]pyruvate enables direct in vivo assessment of real-time liver enzymatic activities by C magnetic resonance. However, the technique usually requires the injection of a highly supraphysiological dose of pyruvate. We herein demonstrate that liver metabolism can be measured in vivo with hyperpolarized [1-C]pyruvate administered at two- to three-fold the basal plasma concentration.

Labile Photo-Induced Free Radical in α-Ketoglutaric Acid: a Universal Endogenous Polarizing Agent for In Vivo Hyperpolarized C Magnetic Resonance.

Hyperpolarized (HP) C magnetic resonance enables non-invasive probing of metabolism in vivo. To date, only C-molecules hyperpolarized with persistent trityl radicals have been injected in humans. We show here that the free radical photo-induced in alpha-ketoglutaric acid (α-KG) can be used to hyperpolarize photo-inactive C-molecules such as [1-C]lactate.

Assessment of Aspartate and Bicarbonate Produced From Hyperpolarized [1-C]Pyruvate as Markers of Renal Gluconeogenesis.

As both a consumer and producer of glucose, the kidney plays a significant role in glucose homeostasis. Measuring renal gluconeogenesis requires invasive techniques, and less invasive methods would allow renal gluconeogenesis to be measured more routinely. Magnetic resonance spectroscopy and imaging of infused substrates bearing hyperpolarized carbon-13 spin labels allows metabolism to be detected within the body with excellent sensitivity.