Staff member

From complex -mixture analysis to in vivo molecular imaging, applications of liquid -state nuclear spin hyperpolarization have expanded widely over recent years. In most cases, hyperpolarized solutions are generated and transported from the polarization instrument to the measurement device. The sample hyperpolarization usually survives this transport, since the changes in magnetic fields that are external to the sample are typically adiabatic (slow) with respect to the internal nuclear spin dynamics. The passage of polarized samples through weakly magnetic components such as stainless steel syringe needles and ferrules is not always adiabatic, can lead to near -complete destruction of the magnetization. To avoid this effect becoming "folklore"in field of hyperpolarized NMR, we present a systematic investigation to highlight the problem and investigate possible solutions. Experiments were carried out on: (i) dissolution-DNP-polarized [1-13C]pyruvate with detection at 1.4 T, and (ii) 1.5 -T -polarized H2O with NMR detection at 2.5 mu T. We show that the degree adiabaticity of solutions passing through metal parts is intrinsically unpredictable, likely depending on factors such as solution flow rate, degree of remanent ferromagnetism in the metal, and nuclear spin However, the magnetization destruction effects can be suppressed by application of an external field order of 0.1-10 mT.

JTD Keywords: Benchtop nmr, Hyperpolarization, Low-field mri, Non-adiabatic, Para-hydrogen, Spin relaxation

We demonstrate that enzyme-catalyzed reactions can be observed in zero- and low-field NMR experiments by combining recent advances in parahydrogen-based hyperpolarization methods with state-of-the-art magnetometry. Specifically, we investigated two model biological processes: the conversion of fumarate into malate, which is used in vivo as a marker of cell necrosis, and the conversion of pyruvate into lactate, which is the most widely studied metabolic process in hyperpolarization-enhanced imaging. In addition to this, we constructed a microfluidic zero-field NMR setup to perform experiments on microliter-scale samples of [1-C-13]-fumarate in a lab-on-a-chip device. Zero- to ultralow-field (ZULF) NMR has two key advantages over high-field NMR: the signals can pass through conductive materials (e.g., metals), and line broadening from sample heterogeneity is negligible. To date, the use of ZULF NMR for process monitoring has been limited to studying hydrogenation reactions. In this work, we demonstrate this emerging analytical technique for more general reaction monitoring and compare zero- vs low-field detection.

JTD Keywords: Fumarates, Hydrogenation, Magnetic resonance imaging, Magnetic resonance spectroscopy, Nmr j-spectroscopy, Pyruvic acid

The sensitivity of NMR may be enhanced by more than four orders of magnitude via dissolution dynamic nuclear polarization (dDNP), potentially allowing real-time, in situ analysis of chemical reactions. However, there has been no widespread use of the technique for this application and the major limitation has been the low experimental throughput caused by the time-consuming polarization build-up process at cryogenic temperatures and fast decay of the hyper-intense signal post dissolution. To overcome this limitation, we have developed a microfluidic device compatible with dDNP-MR spectroscopic imaging methods for detection of reactants and products in chemical reactions in which up to 8 reactions can be measured simultaneously using a single dDNP sample. Multiple MR spectroscopic data sets can be generated under the same exact conditions of hyperpolarized solute polarization, concentration, pH, and temperature. A proof-of-concept for the technology is demonstrated by identifying the reactants in the decarboxylation of pyruvate via hydrogen peroxide (e.g. 2-hydroperoxy-2-hydroxypropanoate, peroxymonocarbonate and CO2). dDNP-MR allows tracing of fast chemical reactions that would be barely detectable at thermal equilibrium by MR. We envisage that dDNP-MR spectroscopic imaging combined with microfluidics will provide a new high-throughput method for dDNP enhanced MR analysis of multiple components in chemical reactions and for non-destructive in situ metabolic analysis of hyperpolarized substrates in biological samples for laboratory and preclinical research.

JTD Keywords: injections, nmr, pyruvate, Polarization

We show that catalyst-free aqueous solutions of hyperpolarized [1-13C]succinate can be produced using parahydrogen-induced polarization (PHIP) and a combination of homogeneous and heterogeneous catalytic hydrogenation reactions. We generate hyperpolarized [1-13C]fumarate via PHIP using para-enriched hydrogen gas with a homogeneous ruthenium catalyst, and subsequently remove the toxic catalyst and reaction side products via a purification procedure. Following this, we perform a second hydrogenation reaction using normal hydrogen gas to convert the fumarate into succinate using a solid Pd/Al2O3 catalyst. This inexpensive polarization protocol has a turnover time of a few minutes, and represents a major advance for in vivo applications of [1-13C]succinate as a hyperpolarized contrast agent.

JTD Keywords: acid, c-13, conversion, fumarate, in-vivo, metabolism, order, Induced polarization

JTD Keywords: Acquisition, C-13, Detecting tumor response, Exchang, Excitation pulses, Magnetic-resonance-spectroscopy, Metabolism, Mri, Resolution, Strategies

Liver fibrosis staging is a key element driving the prognosis of patients with chronic liver disease. Currently, biopsy is the only technique capable of diagnosing liver fibrosis in patients with alcohol-related liver disease (ArLD) and non-alcoholic fatty liver disease (NAFLD) unequivocally. Non-invasive (e.g. plasma-based) biomarker assays are attractive tools to diagnose and stage disease, yet must prove that they are reliable and sensitive to be used clinically. Here we demonstrate 1 H nuclear magnetic resonance as a method to rapidly quantify the endogenous concentration of ammonium ions from human plasma extracts and show their ability to report upon early and advanced stages of ArLD and NAFLD. We show that, irrespective of the disease aetiology, ammonium concentration is a more robust and informative marker of fibrosis stage than current clinically assessed blood hepatic biomarkers. Subject to validation in larger cohorts, the study indicates that the method can provide accurate and rapid staging of ArLD and NAFLD without need for an invasive biopsy.This article is protected by copyright. All rights reserved.

JTD Keywords: ammonium quantification, blood biomarkers, chronic liver disease, disease biomarkers, hepatic dysfunction, nmr, pathogenesis, Ammonium quantification, Hepatic dysfunction, Hepatic-encephalopathy

Technologies to cryogenically preserve (a.k.a. cryopreserve) living tissue, cell lines and primary cells have matured greatly for both clinicians and researchers since their first demonstration in the 1950s and are widely used in storage and transport applications. Currently, however, there remains an absence of viable cryopreservation and thawing methods for bioengineered, three-dimensional (3D) cell models, including patients' samples. As a first step towards addressing this gap, we demonstrate a viable protocol for spheroid cryopreservation and survival based on a 3D carboxymethyl cellulose scaffold and precise conditions for freezing and thawing. The protocol is tested using hepatocytes, for which the scaffold provides both the 3D structure for cells to self-arrange into spheroids and to support cells during freezing for optimal post-thaw viability. Cell viability after thawing is improved compared to conventional pellet models where cells settle under gravity to form a pseudo-tissue before freezing. The technique may advance cryobiology and other applications that demand high-integrity transport of pre-assembled 3D models (from cell lines and in future cells from patients) between facilities, for example between medical practice, research and testing facilities.

JTD Keywords: 3d cell culture, biofabrication, biomaterials, carboxymethyl cellulose, cryopreservation, hepatocytes, 3d cell culture, Biofabrication, Biomaterials, Carboxymethyl cellulose, Cell culture techniques, three dimensional, Cell survival, Cryopreservation, Freezing, Hepatocytes, Humans, Prevention, Scaffolds, Spheroids

Cryopreservation methods for cell and tissue storage have beenaround since 1954, where thawed sperm samples were used for aninsemination. Since then, the technology has evolved for cliniciansand researchers to cryopreserve tissue, cell lines and primary cells.While cryopreserving tissues helps maintain their physiological in-tegrity for study it does not assure the viability of the cells afterthawing. Furthermore, the cells cryopreserved in suspension losetheir dimensional anchors, forcing them to change their morphology.To solve this issue, tissue engineering allows researchers to create 3Dculture models, such as organoids and bioprinted cell clusters, thatmimic the physiological characteristics of the cells in tissue anddisease. Although this culture methods present promising results,there is a lack of methodology to cryopreserve 3D cell models andpatients’ samples for storage and transport in a way where they re-main viable after thawing. We propose a protocol that uses a car-boxymethyl cellulose scaffold and precise freezing and thawingconditions for spheroid survival. The scaffold provides structure forthe hepatocytes to create spheroids on their own as well as supportthroughout the freezing and thawing processes for optimal cell via-bility post-thawing. Furthermore, this method will achieve highercell viability than transporting the cells as a cryopreserved pellet formodel assembling after thawing, allowing the cells to settle and forma tissue beforehand to improve viability after cryopreservation. Thistechnique constitutes a step forward for it will facilitate the transportof already assembled 3D models from cell lines or primary cells frompatients.

JTD Keywords: Cryopreservation

An anaerobic stable mixed culture dominated by bacteria belonging to the genera Dehalobacterium, Acetobacterium, Desulfovibrio, and Wolinella was used as a model to study the microbial interactions during DCM degradation. Physiological studies indicated that DCM was degraded in this mixed culture at least in a three-step process: i) fermentation of DCM to acetate and formate, ii) formate oxidation to CO2 and H2, and iii) H2/CO2 reductive acetogenesis. The 16S rRNA gene sequencing of cultures enriched with formate or H2 showed that Desulfovibrio was the dominant population followed by Acetobacterium, but sequences representing Dehalobacterium were only present in cultures amended with DCM. Nuclear magnetic resonance analyses confirmed that acetate produced from 13C-labelled DCM was marked at the methyl ([2–13C]acetate), carboxyl ([1–13C]acetate), and both ([1,2–13C]acetate) positions, which is in accordance to acetate formed by both direct DCM fermentation and H2/CO2 acetogenesis. The inhibitory effect of ten different co-contaminants frequently detected in groundwaters on DCM degradation was also investigated. Complete inhibition of DCM degradation was observed when chloroform, perfluorooctanesulfonic acid, and diuron were added at 838, 400, and 107 μM, respectively. However, the inhibited cultures recovered the DCM degradation capability when transferred to fresh medium without co-contaminants. Findings derived from this work are of significant relevance to provide a better understanding of the synergistic interactions among bacteria to accomplish DCM degradation as well as to predict the effect of co-contaminants during anaerobic DCM bioremediation in groundwater. © 2019 Elsevier Ltd

JTD Keywords: Bioremediation, Co-contaminants, Dehalobacterium, Dichloromethane, Inhibition