Directly Bound Deuterons Increase X-Nuclei Hyperpolarization using Dynamic Nuclear Polarization.

Deuterated C sites in sugars (D-glucose and 2-deoxy-D-glucose) showed 6.3-to-17.5-fold higher solid-state dynamic nuclear polarization (DNP) levels than their respective protonated sites at 3.

Real-time influence of intracellular acidification and Na /H exchanger inhibition on in-cell pyruvate metabolism in the perfused mouse heart: A P-NMR and hyperpolarized C-NMR study.

Disruption of acid-base balance is linked to various diseases and conditions. In the heart, intracellular acidification is associated with heart failure, maladaptive cardiac hypertrophy, and myocardial ischemia. Previously, we have reported that the ratio of the in-cell lactate dehydrogenase (LDH) to pyruvate dehydrogenase (PDH) activities is correlated with cardiac pH.

Investigating Cardiac Metabolism in the Isolated Perfused Mouse Heart with Hyperpolarized [1-13C]Pyruvate and 13C/31P NMR Spectroscopy.

Metabolism is the basis of important processes in cellular life. Characterizing how metabolic networks function in living tissues provides crucial information for understanding the mechanism of diseases and designing treatments. In this work, we describe procedures and methodologies for studying in-cell metabolic activity in a retrogradely perfused mouse heart in real-time.

Signal enhancement of hyperpolarized N sites in solution-increase in solid-state polarization at 3.35 T and prolongation of relaxation in deuterated water mixtures.

Hyperpolarized N sites have been found to be promising for generating long-lived hyperpolarized states in solution, and present a promising approach for utilizing dissolution-dynamic nuclear polarization (dDNP)-driven hyperpolarized MRI for imaging in biology and medicine. Specifically, N sites with directly bound protons were shown to be useful when dissolved in D O. The purpose of the current study was to further characterize and increase the visibility of such N sites in solutions that mimic an intravenous injection during the first cardiac pass in terms of their H O:D O composition.

Tolerance of Rodents to an Intravenous Bolus Injection of Sodium Nitrate in a High Concentration.

Nitrate, the inorganic anion NO, is found in many foods and is an endogenous mammalian metabolite, which is supplied mostly through the diet. Although much is known about the safety of sodium nitrate when given , methodological safety data on intravenous bolus injection of sodium nitrate to rodents are lacking. Recently, we have proposed a new use for nitrate, as a contrast agent for magnetic resonance imaging that will be metal free and leave no traces in the body and the environment further to the imaging examination.

Accumulation of 3-aminopropylphosphonate in the ex vivo brain observed by phosphorus-31 nuclear magnetic resonance.

3-aminopropylphosphonate (3-APP) is known for its use as an exogenous indicator of extracellular volume and pH in phosphorus-31 nuclear magnetic resonance ( P NMR) studies. We used 3-APP for estimating the extracellular volume in NMR studies of several ex vivo preparations including retrograde perfused mouse heart (n = 4), mouse liver slices (n = 2), xenograft breast cancer tumors (n = 7, MCF7), and rat brain slices (n = 4). In the former three preparations, the 3-APP signal was stable in lineshape and intensity for hours and the chemical shift of the signal in the presence of the biological sample was the same as in the perfusion medium without the biological sample.

Real-Time Non-Invasive and Direct Determination of Lactate Dehydrogenase Activity in Cerebral Organoids-A New Method to Characterize the Metabolism of Brain Organoids?

Organoids are a powerful tool in the quest to understand human diseases. As the developing brain is extremely inaccessible in mammals, cerebral organoids (COs) provide a unique way to investigate neural development and related disorders. The aim of this study was to utilize hyperpolarized C NMR to investigate the metabolism of COs in real-time, in a non-destructive manner.

Curbing action potential generation or ATP-synthase leads to a decrease in in-cell pyruvate dehydrogenase activity in rat cerebrum slices.

Direct and real-time monitoring of cerebral metabolism exploiting the drastic increase in sensitivity of hyperpolarized C-labeled metabolites holds the potential to report on neural activity via in-cell metabolic indicators. Here, we followed the metabolic consequences of curbing action potential generation and ATP-synthase in rat cerebrum slices, induced by tetrodotoxin and oligomycin, respectively. The results suggest that pyruvate dehydrogenase (PDH) activity in the cerebrum is 4.

LDH and PDH Activities in the Ischemic Brain and the Effect of Reperfusion-An Ex Vivo MR Study in Rat Brain Slices Using Hyperpolarized [1-C]Pyruvate.

Ischemic stroke is a leading cause for neurologic disability worldwide, for which reperfusion is the only available treatment. Neuroimaging in stroke guides treatment, and therefore determines the clinical outcome. However, there are currently no imaging biomarkers for the status of the ischemic brain tissue.

The metabolic representation of ischemia in rat brain slices: A hyperpolarized C magnetic resonance study.

The ischemic penumbra in stroke is not clearly defined by today's available imaging tools. This study aimed to develop a model system and noninvasive biomarkers of ischemic brain tissue for an examination that might potentially be performed in humans, very quickly, in the course of stroke triage. Perfused rat brain slices were used as a model system and P spectroscopy verified that the slices were able to recover from an ischemic insult of about 3.

Correlation between lactate dehydrogenase/pyruvate dehydrogenase activities ratio and tissue pH in the perfused mouse heart: A potential noninvasive indicator of cardiac pH provided by hyperpolarized magnetic resonance.

Cardiovascular diseases account for more than 30% of all deaths worldwide and many could be ameliorated with early diagnosis. Current cardiac imaging modalities can assess blood flow, heart anatomy and mechanical function. However, for early diagnosis and improved treatment, further functional biomarkers are needed.

Observation of glucose-6-phosphate anomeric exchange in real-time using dDNP hyperpolarised NMR.

A hyperpolarised-NMR acquisition approach that is sensitive to the process of glucose-6-phosphate anomerization is presented. Using selective depolarisation of one of the anomer's signals, it is possible to observe the replenishing of this signal due to the fast anomeric exchange of this compound. The forward to reverse reaction rate constants ratio was 1.

Increasing the sensitivity of hyperpolarized [ N ]urea detection by serial transfer of polarization to spin-coupled protons.

Purpose: Hyperpolarized N-labeled molecules have been proposed as imaging agents for investigating tissue perfusion and pH. However, the sensitivity of direct N detection is limited by the isotope's low gyromagnetic ratio. Sensitivity can be increased by transferring N hyperpolarization to spin-coupled protons provided that there is not significant polarization loss during transfer.

The Effect of Gadolinium Doping in [ C , H ]Glucose Formulations on C Dynamic Nuclear Polarization at 3.35 T.

The promise of hyperpolarized glucose as a non-radioactive imaging agent capable of reporting on multiple metabolic routes has led to recent advances in its dissolution-DNP (dDNP) driven polarization using UV-light induced radicals and trityl radicals at high field (6.7 T) and 1.1 K.

[C,D]2-deoxyglucose phosphorylation by hexokinase shows selectivity for the β-anomer.

A non-radioactive 2-deoxyglucose (2DG) analog has been developed here for hyperpolarized magnetic resonance investigations. The analog, [C,D]2DG, showed 13% polarization in solution (27,000-fold signal enhancement at the C site), following a dissolution-DNP hyperpolarization process. The phosphorylation of this analog by yeast hexokinase (yHK) was monitored in real-time with a temporal resolution of 1 s.

Hyperpolarized product selective saturating-excitations for determination of changes in metabolic reaction rates in real-time.

Investigation of hyperpolarized substrate metabolism has been showing utility in real-time determination of in-cell and in vivo enzymatic activities. Intracellular reaction rates may vary during the course of a measurement, even on the very short time scales of visibility on hyperpolarized MR, due to many factors such as the availability of the substrate and co-factors in the intracellular space. Despite this potential variation, the kinetic analysis of hyperpolarized signals typically assumes that the same rate constant (and in many cases, the same rate) applies throughout the course of the reaction as observed via the build-up and decay of the hyperpolarized signals.

In-cell determination of Lactate Dehydrogenase Activity in a Luminal Breast Cancer Model ⁻ Investigation of Excised Xenograft Tumor Slices Using dDNP Hyperpolarized [1-C]pyruvate.

[1-C]pyruvate, the most widely used compound in dissolution-dynamic nuclear polarization (dDNP) magnetic resonance (MR), enables the visualization of lactate dehydrogenase (LDH) activity. This activity had been demonstrated in a wide variety of cancer models, ranging from cultured cells, to xenograft models, to human tumors in situ. Here we quantified the LDH activity in precision cut tumor slices (PCTS) of breast cancer xenografts.

Hyperpolarized [N]nitrate as a potential long lived hyperpolarized contrast agent for MRI.

Reports on gadolinium deposits in the body and brains of adults and children who underwent contrast-enhanced MRI examinations warrant development of new, metal free, contrast agents for MRI. Nitrate is an abundant ion in mammalian biochemistry and sodium nitrate can be safely injected intravenously. We show that hyperpolarized [N]nitrate can potentially be used as an MR tracer.

Real-time ALT and LDH activities determined in viable precision-cut mouse liver slices using hyperpolarized [1- C]pyruvate-Implications for studies on biopsied liver tissues.

Precision-cut liver slices (PCLS) are widely used in liver research as they provide a liver model with all liver cell types in their natural architecture. The purpose of this study was to demonstrate the use of PCLS for hyperpolarized metabolic investigation in a mouse model, for potential future application in liver biopsy cores. Fresh normal liver was harvested from six mice.

Real-time ex-vivo measurement of brain metabolism using hyperpolarized [1-C]pyruvate.

The ability to directly monitor in vivo brain metabolism in real time in a matter of seconds using the dissolution dynamic nuclear polarization technology holds promise to aid the understanding of brain physiology in health and disease. However, translating the hyperpolarized signal observed in the brain to cerebral metabolic rates is not straightforward, as the observed in vivo signals reflect also the influx of metabolites produced in the body, the cerebral blood volume, and the rate of transport across the blood brain barrier. We introduce a method to study rapid metabolism of hyperpolarized substrates in the viable rat brain slices preparation, an established ex vivo model of the brain.

Author Correction: Biochemical phosphates observed using hyperpolarized P in physiological aqueous solutions.

The original version of the Supplementary Information associated with this Article contained an error in Supplementary Figure 2 and Supplementary Figure 5 in which the P NMR spectral lines were missing. The HTML has been updated to include a corrected version of the Supplementary Information.

Long-lived N Hyperpolarization and Rapid Relaxation as a Potential Basis for Repeated First Pass Perfusion Imaging - Marked Effects of Deuteration and Temperature.

Deuteration of the exchangeable hydrogens of [ N ]urea was found to prolong the T of the N sites to more than 3 min at physiological temperatures. This significant increase in the lifetime of the hyperpolarized state of [ N ]urea, compared to [ C]urea - a pre-clinically proven perfusion agent, makes [ N ]urea a promising perfusion agent. The molecular parameters that may lead to this profound effect were assessed by investigating small molecules with different molecular structures containing N sites bound to labile protons and determining the hyperpolarized N T in H O and D O.

Parahydrogen-Based Hyperpolarization for Biomedicine.

Magnetic resonance (MR) is one of the most versatile and useful physical effects used for human imaging, chemical analysis, and the elucidation of molecular structures. However, its full potential is rarely used, because only a small fraction of the nuclear spin ensemble is polarized, that is, aligned with the applied static magnetic field. Hyperpolarization methods seek other means to increase the polarization and thus the MR signal.

Biochemical phosphates observed using hyperpolarized P in physiological aqueous solutions.

The dissolution-dynamic nuclear polarization technology had previously enabled nuclear magnetic resonance detection of various nuclei in a hyperpolarized state. Here, we show the hyperpolarization of P nuclei in important biological phosphates (inorganic phosphate and phosphocreatine) in aqueous solutions. The hyperpolarized inorganic phosphate showed an enhancement factor >11,000 (at 5.

Defective ATP breakdown activity related to an ENTPD1 gene mutation demonstrated using P NMR spectroscopy.

The ecto-nucleoside triphosphate diphosphohydrolase-1 (E-NTPDase-1, CD39) enzyme is responsible for the breakdown of extracellular ATP to ADP and then to AMP by a two-step process. Defective CD39 activity has been described in a variety of medical conditions including malignancy and rheumatic diseases and has been proved to be of major diagnostic and clinical importance. Here we show for the first time that a P NMR spectroscopy methodology enables the quantification of these two steps in a single blood sample.