Direct enhancement of nuclear singlet order by dynamic nuclear polarization

Hyperpolarized singlet order is available immediately after dissolution DNP, avoiding need for additional preparation steps. We demonstrate this procedure on a sample of [1,2–13C2]pyruvic aci

(13) C magnetic resonance spectroscopy measurements with hyperpolarized [1-(13) C] pyruvate can be used to detect the expression of transgenic pyruvate decarboxylase activity in vivo.

PURPOSE: Dissolution dynamic nuclear polarization can increase the sensitivity of the (13) C magnetic resonance spectroscopy experiment by at least four orders of magnitude and offers a novel approach to the development of MRI gene reporters based on enzymes that metabolize (13) C-labeled tracers. We describe here a gene reporter based on the enzyme pyruvate decarboxylase (EC 4.1.1.1), which catalyzes the decarboxylation of pyruvate to produce acetaldehyde and carbon dioxide. METHODS: Pyruvate decarboxylase from Zymomonas mobilis (zmPDC) and a mutant that lacked enzyme activity were expressed using an inducible promoter in human embryonic kidney (HEK293T) cells. Enzyme activity was measured in the cells and in xenografts derived from the cells using (13) C MRS measurements of the conversion of hyperpolarized [1-(13) C] pyruvate to H(13) CO3-. RESULTS: Induction of zmPDC expression in the cells and in the xenografts derived from them resulted in an approximately two-fold increase in the H(13) CO3-/[1-(13) C] pyruvate signal ratio following intravenous injection of hyperpolarized [1-(13) C] pyruvate. CONCLUSION: We have demonstrated the feasibility of using zmPDC as an in vivo reporter gene for use with hyperpolarized (13) C MRS. Magn Reson Med 76:391-401, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.PD was in receipt of a studentship funded by CRUK and S.-S.T. a Yousef Jameel studentship. TBR was in receipt of an Intra-European Marie Curie (FP7-PEOPLE- 2009-IEF, Imaging Lymphoma) and Long-term EMBO (EMBO-ALT-1145-2009) fellowships and E.M.S. and I.M.R were recipients of fellowships from the European Union Seventh Framework Programme (FP7/2007-2013) under the Marie Curie Initial Training Network METAFLUX (project number 264780). E.M.S. also acknowledges the educational support of Programme for Advanced Medical Education from Calouste Gulbenkian Foundation, Champalimaud Foundation, Ministerio de Saude and Fundacao para a Ciencia e Tecnologia, Portugal. The work was supported by a CRUK Programme Grant (17242) to KMB. The polarizer and related materials were provided by GE-Healthcare.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/mrm.2587

Real-Time Polarimetry of Hyperpolarized 13C Nuclear Spins Using an Atomic Magnetometer

We introduce a method for nondestructive quantification of nuclear spin polarization, of relevance to hyperpolarized spin tracers widely used in magnetic resonance from spectroscopy to in vivo imaging. In a bias field of around 30 nT we use a high-sensitivity miniaturized 87Rb-vapor magnetometer to measure the field generated by the sample, as it is driven by a windowed dynamical decoupling pulse sequence that both maximizes the nuclear spin lifetime and modulates the polarization for easy detection. We demonstrate the procedure applied to a 0.08 M hyperpolarized [1-13C]-pyruvate solution produced by dissolution dynamic nuclear polarization, measuring polarization repeatedly during natural decay at Earth's field. Application to real-time and continuous quality monitoring of hyperpolarized substances is discussed

Combined homogeneous and heterogeneous hydrogenation to yield catalyst-free solutions of parahydrogen-hyperpolarized [1-13C]succinate

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

Lab-on-a-Chip Analysis Using Benchtop NMR Technology

We present the design and optimization of a benchtop NMR spectrometer for real-time metabolic monitoring of 3D tissue on microfluidic platforms, utilizing hyperpolarization via dynamic nuclear polarisation. We show the modifications made to a commercial benchtop NMR spectrometer, the design and fabrication of a microfluidic platform ensuring consistent injection of hyperpolarized substrates and ongoing cell media renewal, and its integration with a radio frequency (RF) coil for data transmission and reception (Tx/Rx). Additionally, the construction of a sample carrier is presented. Preliminary NMR results from this system are also provided.This work has received funding from: The European Union’s Horizon 2020 research and innovation program (GA-863037); the Spanish grants with reference PID2020- 117859RA-I00 funded by MCIN/AEI/10.13039/501100011033 (NARMYD), RYC2020-029099-I funded by MCIN/AEI10.13039/501100011033 and by “ESF Investing in your future”, PLEC2022-009256 funded by MCIN/AEI/10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR”; The BIST (Barcelona Institute of Science and Technology)-“la Caixa” Banking Foundation Chemical Biology programme

Lab-on-a-Chip Analysis Using Benchtop NMR Technology

We present the design and optimization of a benchtop NMR spectrometer for real-time metabolic monitoring of 3D tissue on microfluidic platforms, utilizing hyperpolarization via dynamic nuclear polarisation. We show the modifications made to a commercial benchtop NMR spectrometer, the design and fabrication of a microfluidic platform ensuring consistent injection of hyperpolarized substrates and ongoing cell media renewal, and its integration with a radio frequency (RF) coil for data transmission and reception (Tx/Rx). Additionally, the construction of a sample carrier is presented. Preliminary NMR results from this system are also provided.This work has received funding from: The European Union’s Horizon 2020 research and innovation program (GA-863037); the Spanish grants with reference PID2020- 117859RA-I00 funded by MCIN/AEI/10.13039/501100011033 (NARMYD), RYC2020-029099-I funded by MCIN/AEI10.13039/501100011033 and by “ESF Investing in your future”, PLEC2022-009256 funded by MCIN/AEI/10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR”; The BIST (Barcelona Institute of Science and Technology)-“la Caixa” Banking Foundation Chemical Biology programme

Assessing Oxidative Stress in Tumors by Measuring the Rate of Hyperpolarized [1-13^{13}C] Dehydroascorbic Acid Reduction Using 13^{13}C Magnetic Resonance Spectroscopy

Rapid cancer cell proliferation promotes the production of reducing equivalents, which counteract the effects of relatively high levels of reactive oxygen species (ROS). ROS levels increase in response to chemotherapy and cell death while an increase in antioxidant capacity can confer resistance to chemotherapy and is associated with an aggressive tumor phenotype. The pentose phosphate pathway (PPP) is a major site of NADPH production in the cell, which is used to maintain the main intracellular antioxidant, glutathione, in its reduced state. Previous studies have shown that the rate of hyperpolarized [1-$^{13}$C]dehydroascorbic acid (DHA) reduction, which can be measured $\textit{in vivo}$ using non-invasive $^{13}$C magnetic resonance spectroscopic imaging, is increased in tumors and that this is correlated with the levels of reduced glutathione. We show here that the rate of hyperpolarized [1-$^{13}$C]DHA reduction is increased in tumors that have been oxidatively pre-stressed by depleting the glutathione pool by buthionine sulfoximine treatment. This increase was associated with a corresponding increase in PPP flux, assessed using $^{13}$C-labeled glucose, and an increase in glutaredoxin activity, which catalyzes the glutathione-dependent reduction of DHA. These results show that the rate of DHA reduction does not depend only on the level of reduced glutathione, but also on the rate of NADPH production, contradicting the conclusions of some previous studies. Hyperpolarized [1-$^{13}$C]DHA can be used therefore to assess the capacity of tumor cells to resist oxidative stress in vivo. However, DHA administration resulted in transient respiratory arrest and cardiac depression, which may prevent translation to the clinic.Work in K.M. Brindle’s laboratory is supported by a Cancer Research UK Programme grant (17242) and the CRUK-EPSRC Imaging Centre in Cambridge and Manchester (16465). K.N. Timm was in receipt of MRC and Cancer Research UK studentships, B.W.C. Kennedy and P. Dzien Cancer Research UK studentships and F. Bulat a CRUK -EPSRC Imaging Centre imaging center studentship. I. Marco -Rius acknowledges the European Union Seventh Framework Programme (FP7/2007-2013) for support under the M arie Curie Initial Training Network METAFLUX (project number 264780)

Four-month incidence of suicidal thoughts and behaviors among healthcare workers after the first wave of the Spain COVID-19 pandemic

[EN] Healthcare workers (HCW) are at high risk for suicide, yet little is known about the onset of suicidal thoughts and behaviors (STB) in this important segment of the population in conjunction with the COVID-19 pandemic. We conducted a multicenter, prospective cohort study of Spanish HCW active during the COVID-9 pandemic. A total of n = 4809 HCW participated at baseline (May–September 2020; i.e., just after the first wave of the pandemic) and at a four-month follow-up assessment (October–December 2020) using web-based surveys. Logistic regression assessed the individual- and population-level associations of separate proximal (pandemic) risk factors with four-month STB incidence (i.e., 30-day STB among HCW negative for 30-day STB at baseline), each time adjusting for distal (pre-pandemic) factors. STB incidence was estimated at 4.2% (SE = 0.5; n = 1 suicide attempt). Adjusted for distal factors, proximal risk factors most strongly associated with STB incidence were various sources of interpersonal stress (scaled 0–4; odds ratio [OR] range = 1.23–1.57) followed by personal health-related stress and stress related to the health of loved ones (scaled 0–4; OR range 1.30–1.32), and the perceived lack of healthcare center preparedness (scaled 0–4; OR = 1.34). Population-attributable risk proportions for these proximal risk factors were in the range 45.3–57.6%. Other significant risk factors were financial stressors (OR range 1.26–1.81), isolation/quarantine due to COVID-19 (OR = 1.53) and having changed to a specific COVID-19 related work location (OR = 1.72). Among other interventions, our findings call for healthcare systems to implement adequate conflict communication and resolution strategies and to improve family-work balance embedded in organizational justice strategies.S

Direct Enhancement of Nuclear Singlet Order by Dynamic Nuclear Polarization

Hyperpolarized singlet order is available immediately after dissolution DNP, avoiding need for additional preparation steps. We demonstrate this procedure on a sample of [1,2–13C2]pyruvic aci