Journal of Magnetic Resonance Open最新文献

{"title":"Facile hyperpolarization chemistry for molecular imaging and metabolic tracking of [1–13C]pyruvate in vivo","authors":"Keilian MacCulloch ,&nbsp;Austin Browning ,&nbsp;David O. Guarin Bedoya ,&nbsp;Stephen J. McBride ,&nbsp;Mustapha B. Abdulmojeed ,&nbsp;Carlos Dedesma ,&nbsp;Boyd M. Goodson ,&nbsp;Matthew S. Rosen ,&nbsp;Eduard Y. Chekmenev ,&nbsp;Yi-Fen Yen ,&nbsp;Patrick TomHon ,&nbsp;Thomas Theis","doi":"10.1016/j.jmro.2023.100129","DOIUrl":"https://doi.org/10.1016/j.jmro.2023.100129","url":null,"abstract":"<div><p>Hyperpolarization chemistry based on reversible exchange of parahydrogen, also known as Signal Amplification By Reversible Exchange (SABRE), is a particularly simple approach to attain high levels of nuclear spin hyperpolarization, which can enhance NMR and MRI signals by many orders of magnitude. SABRE has received significant attention in the scientific community since its inception because of its relative experimental simplicity and its broad applicability to a wide range of molecules, however, <em>in vivo</em> detection of molecular probes hyperpolarized by SABRE has remained elusive. Here we describe a first demonstration of SABRE-hyperpolarized contrast detected <em>in vivo</em>, specifically using hyperpolarized [1–¹³C]pyruvate. Biocompatible formulations of hyperpolarized [1–¹³C]pyruvate in, both, methanol-water, and ethanol-water mixtures followed by dilution with saline and catalyst filtration were prepared and injected into healthy Sprague Dawley and Wistar rats. Effective hyperpolarization-catalyst removal was performed with silica filters without major losses in hyperpolarization. Metabolic conversion of pyruvate to lactate, alanine, and bicarbonate was detected <em>in vivo</em>. Pyruvate-hydrate was also observed as a minor byproduct. Measurements were performed on the liver and kidney at 4.7 T via time-resolved spectroscopy and chemical-shift-resolved MRI. In addition, whole-body metabolic measurements were obtained using a cryogen-free 1.5 T MRI system, illustrating the utility of combining lower-cost MRI systems with simple, low-cost hyperpolarization chemistry to develop safe and scalable molecular imaging.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"16 ","pages":"Article 100129"},"PeriodicalIF":2.624,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3266171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CPMAS NMR platform for direct compositional analysis of mycobacterial cell-wall complexes and whole cells","authors":"Xinyu Liu ,&nbsp;Jasna Brčić ,&nbsp;Gail H. Cassell ,&nbsp;Lynette Cegelski","doi":"10.1016/j.jmro.2023.100127","DOIUrl":"10.1016/j.jmro.2023.100127","url":null,"abstract":"<div><p>Tuberculosis and non-tuberculosis mycobacterial infections are rising each year and often result in chronic incurable disease. Important antibiotics target cell-wall biosynthesis, yet some mycobacteria are alarmingly resistant or tolerant to currently available antibiotics. This resistance is often attributed to assumed differences in composition of the complex cell wall of different mycobacterial strains and species. However, due to the highly crosslinked and insoluble nature of mycobacterial cell walls, direct comparative determinations of cell-wall composition pose a challenge to analysis through conventional biochemical analyses. We introduce an approach to directly observe the chemical composition of mycobacterial cell walls using solid-state NMR spectroscopy. ¹³C CPMAS spectra are provided of individual components (peptidoglycan, arabinogalactan, and mycolic acids) and of <em>in situ</em> cell-wall complexes. We assigned the spectroscopic contributions of each component in the cell-wall spectrum. We uncovered a higher arabinogalactan-to-peptidoglycan ratio in the cell wall of <em>M. abscessus</em>, an organism noted for its antibiotic resistance, relative to <em>M. smegmatis</em>. Furthermore, differentiating influences of different types of cell-wall targeting antibiotics were observed in spectra of antibiotic-treated whole cells. This platform will be of value in evaluating cell-wall composition and antibiotic activity among different mycobacteria and in considering the most effective combination treatment regimens.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"16 ","pages":"Article 100127"},"PeriodicalIF":2.624,"publicationDate":"2023-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666441023000353/pdfft?md5=b8e77d4be33bc168b0286ba8cff3b61a&pid=1-s2.0-S2666441023000353-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85315161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Affordable amino acid α/β-deuteration and specific labeling for NMR signal enhancement: Evaluation on the kinase p38α","authors":"Rania Ghouil ,&nbsp;Chafiaa Bouguechtouli ,&nbsp;Hélène Chérot ,&nbsp;Agathe Marcelot ,&nbsp;Maxime Roche ,&nbsp;Francois-Xavier Theillet","doi":"10.1016/j.jmro.2023.100126","DOIUrl":"https://doi.org/10.1016/j.jmro.2023.100126","url":null,"abstract":"<div><p>Although very effective in decreasing NMR relaxation of large proteins, homogeneous deuteration can be costly, and anyway unsuitable for recombinant production in metazoan systems. We sought to explore other deuteration schemes, which would be adapted to protein expression in mammalian cells. Here, we evaluate the benefits of the deuteration on alpha- and beta-positions of amino acids for a typical middle size protein domain, namely the model 40 kDa-large kinase p38α. We report the position-specific deuteration of free amino acids by using enzyme-assisted H/D exchange, executed by the cystathionine gamma-synthase and a newly designed high-performance mutant E325A. Then, we used cell-free expression in bacterial extracts to avoid any scrambling and back-protonation of the tested isotopically labelled amino acids (Ala, Leu, Lys, Ser, Asp, Glu, Gly). Our results show signal enhancements up to three in ¹H-¹⁵N spectra when these α/β-deuterated amino acids are integrated. Because our approach relies on single ²H_α/β-¹⁵N-amino acid labeling, an additional three-fold increase in sensitivity is obtained by the possible use of moderate resolution SOFAST-HMQC instead of the classical HSQC or TROSY experiments. This allows recording residue-resolved solution ¹H-¹⁵N NMR spectra of 100 μg of p38α in one hour with S/N∼10.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"16 ","pages":"Article 100126"},"PeriodicalIF":2.624,"publicationDate":"2023-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1826370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A primer to polarizing agent design: Quantum mechanical understanding of cross effect magic-angle spinning Dynamic Nuclear Polarization","authors":"Lydia Gkoura ,&nbsp;Asif Equbal","doi":"10.1016/j.jmro.2023.100125","DOIUrl":"10.1016/j.jmro.2023.100125","url":null,"abstract":"<div><p>Dynamic Nuclear Polarization (DNP) is transforming the landscape of solid-state characterization for both biological solids and functional materials. By transferring electron spin polarization to coupled nuclear spins under microwave irradiation, DNP increases NMR sensitivity by several orders of magnitude. However, the mechanism of DNP transfer and its efficiency under magic-angle spinning (MAS) significantly differs from that under static conditions. This primer article provides a comprehensive and pedagogical explanation of the theoretical aspects of MAS-DNP, with a specific focus on the cross-effect mechanism. A clear understanding of the nuances of MAS-DNP is crucial for improving its efficiency and extending its application to high magnetic fields and fast MAS conditions. To this end, the article proposes a guideline for synthetic chemists to develop DNP polarizing agents under these experimental conditions.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"16 ","pages":"Article 100125"},"PeriodicalIF":2.624,"publicationDate":"2023-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S266644102300033X/pdfft?md5=04fd482932dc3eae839d2bc3109ace6b&pid=1-s2.0-S266644102300033X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86288119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modelling of T1 dispersion effects on fluid polarization in oil flow","authors":"Rutger R. Tromp,&nbsp;Leo Pel,&nbsp;David M.J. Smeulders","doi":"10.1016/j.jmro.2023.100124","DOIUrl":"https://doi.org/10.1016/j.jmro.2023.100124","url":null,"abstract":"<div><p>In this article we use numerical simulations to study the effect of <em>T</em>₁ dispersion on fluid polarization buildup in oil flow to characterize the sensitivity of both a conventional NMR concept (ROI located inside the polarization magnet) and a Earth's field NMR concept (ROI outside and downstream of the polarization magnet) to <em>T</em>₁ dispersion of flowing samples. As a polarization field in both concepts we use a 90 cm long Halbach magnet. The <em>T</em>₁ dispersion behavior of the oils is based on a set of crude oils that span a viscosity range of 0.7 cP up to 2·10⁴ cP and <em>T</em>₁ relaxation measurements for Larmor frequencies between 10 kHz and 20 MHz. Numerical simulations based on solving the Bloch-Torrey equation for the longitudinal magnetization component show that fluid polarization levels in a ROI of a Earth's field NMR system concept are much more strongly affected by <em>T</em>₁ dispersion than in the conventional NMR system concept. As a result, we may conclude that the Earth's field NMR system design is less robust for measuring flowing samples that show strong <em>T</em>₁ dispersion behavior. In comparison, the conventional NMR system design is relatively insensitive to the effect of <em>T</em>₁ dispersion, as <em>T</em>₁ dispersion effects were found to form a relatively small correction to the magnetization buildup. The conventional NMR system design consequently is the preferred implementation of a NMR system that operates on fluids with strong <em>T</em>₁ dispersion behavior. We show that in the presence of <em>T</em>₁ dispersion <em>s</em> = <em>vT</em>₁(0)/<em>L_m*</em> may be used as a governing parameter for fluid polarization buildup, where <em>T</em>₁(0) is the <em>T</em>₁ relaxation time in the center of the polarization magnet, and we show how an modified analytical uniform field model can be used to describe fluid polarization for a uniform flow velocity distribution in the presence of <em>T</em>₁ dispersion with an accuracy within 1% for the samples and field distribution considered in this study at industrially relevant flow velocities.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"16 ","pages":"Article 100124"},"PeriodicalIF":2.624,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3451238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Background removal from rapid-scan EPR spectra of nitroxide-based spin labels by minimizing non-quadratic cost functions","authors":"Florian Johannsen,&nbsp;Malte Drescher","doi":"10.1016/j.jmro.2023.100121","DOIUrl":"https://doi.org/10.1016/j.jmro.2023.100121","url":null,"abstract":"<div><p>Rapid-scan electron paramagnetic resonance spectroscopy is an emerging technique which substantially improves the signal-to-noise ratio and time resolution compared to conventional continuous-wave experiments. This allows the investigation of spin-labeled biomolecules and their structural dynamics on much shorter time scales than usually accessible. The EPR spectrum however is superimposed by a strong background that is caused by microphonic effects of the alternating magnetic field. This article discusses the use of non-quadratic cost functions for background removal of rapid-scan spectra. The method is validated for the most prominent type of spin-probes in the field of biochemistry: the nitroxide spin-label.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"16 ","pages":"Article 100121"},"PeriodicalIF":2.624,"publicationDate":"2023-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1826466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Steady-State Free Precession sequences for high and low field NMR spectroscopy in solution: Challenges and opportunities","authors":"Tiago Bueno Moraes ,&nbsp;Flávio Vinícius Crizóstomo Kock ,&nbsp;Kahlil Schwanka Salome ,&nbsp;Andersson Barison ,&nbsp;Andre Simpson ,&nbsp;Luiz Alberto Colnago","doi":"10.1016/j.jmro.2022.100090","DOIUrl":"https://doi.org/10.1016/j.jmro.2022.100090","url":null,"abstract":"<div><p>The receptivity of NMR spectroscopy is low when compared to other techniques. Historically, increasing the strength of the static magnetic field has been the major approach to increase NMR sensitivity. In recent years several polarization transfer protocols have been used to enhance the signal-to-noise ratio (SNR), although they require special accessories and/or sample preparation. In this paper, we consider both the challenges and opportunities of steady-state free precession (SSFP) pulse sequences as a simple and efficient alternative to enhance SNR, in standard high-resolution and benchtop low-resolution NMR spectrometers. The maximum gain in these sequences is obtained with the shortest time between the pulses (Tp). However, when Tp&lt;T₂, the SSFP signal contains FID and echo components which lead to phase, intensity, and truncation artifacts on spectra obtained by Fast Fourier transform (FT). Several phase alternation SSFP sequences were used to cancel the echo component and minimize these problems in the FT spectra. Krylov base diagonalization method (KBDM) was used to eliminate the phase and truncation problems in spectra acquired by SSFP pulse sequences and can be a viable alternative to FT. The experiments were performed in high and low resolution (bench top) NMR spectrometers and significant enhancements in SNR of low receptivity nuclei such as ¹³C and ¹⁵N could be achieved. The SSFP sequences were also shown to enhance SNR in nuclei with high receptivity such as ¹⁹F and ³¹P, in very dilute samples, as is common in environmental and biological samples.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100090"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1826375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probing disorder and dynamics in composite electrolytes of an organic ionic plastic crystal and lithium functionalised acrylic polymer nanoparticles","authors":"Yady García ,&nbsp;Luca Porcarelli ,&nbsp;Haijin Zhu ,&nbsp;Maria Forsyth ,&nbsp;David Mecerreyes ,&nbsp;Luke A. O'Dell","doi":"10.1016/j.jmro.2023.100095","DOIUrl":"https://doi.org/10.1016/j.jmro.2023.100095","url":null,"abstract":"<div><p>Solid composite electrolytes combining an ionic molecular phase to facilitate ion transport with a polymeric component to provide mechanical strength are promising material for solid-state batteries. However, the structure-property relationships of these complex composites are not fully understood. Herein we study composites combining the non-flammability and thermal stability of the organic ionic plastic crystal (OIPC) N-methyl-N-ethylpyrrolidinium bis(trifluoromethanesulfonyl) amide [C₂mpyr][TFSI] with the mechanical strength of acrylic polymer nanoparticles functionalised with sulphonamide groups having lithium counter-cations. The effect of the formation of interfaces and interfacial regions between the OIPC and polymer nanoparticle on the thermal stability, ion transport, morphology and ion dynamics were studied. It was found that the composites where an interphase was formed by local mixing of the polymer with the OIPC upon heating showed higher local disorder in the OIPC phase and enhanced ion transport in comparison with the as-prepared composites. In addition, doping the composite with LiTFSI salt led to further structural disorder in the OIPC and a selective increase in lithium-ion mobility. Such an improved fundamental understanding of structure, dynamics and interfacial regions in solid electrolyte composites can inform the design of OIPC-polymer nanoparticle composites with enhanced properties for application as solid electrolyte in batteries.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100095"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3135447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CEST-based detection of labile protons by ultrafast 2D NMR","authors":"Ricardo P. Martinho ,&nbsp;Gregory L. Olsen ,&nbsp;Lucio Frydman","doi":"10.1016/j.jmro.2023.100096","DOIUrl":"https://doi.org/10.1016/j.jmro.2023.100096","url":null,"abstract":"<div><p>Chemical exchange saturation transfer (CEST) NMR is widely used for enhancing the sensitivity of low-abundance exchanging sites in general, and for the water-based detection of labile metabolite protons under <em>in vivo</em> conditions in particular. CEST, however, faces a number of limitations when targeting multiple metabolites, including a radiofrequency (RF)-induced broadening of the detected peaks, and relatively long acquisition times deriving from its continuous-wave nature. Methods have been proposed to overcome these limitations, including a Fourier-encoded version of CEST –the Frequency-Labeled EXchange (FLEX) experiment– and the incorporation of background gradients during the RF saturation time. This work explores an alternative avenue, based on spatiotemporally encoded ultrafast (UF) 2D NMR. UF NMR can compress the time-domain indirect-dimension encoding of 2D NMR into a single shot; to exploit these potential time savings, an UF version of the FLEX experiment was taken as starting point, and the multiple t₁-incremented amplitude modulation cycles that the FLEX experiment normally requires were replaced by a single-shot spatiotemporal encoding. The ensuing UF 2D FLEX experiment was then used to monitor the spectral signatures of multiple moieties as they exchange with the solvent, by imprinting these onto the water resonance as in the original experiment –but now all within a single shot. Upon incorporating two-scan phase cycling and quadrature detection, the resulting method showed an experimental performance similar to <em>t₁</em>-encoded FLEX, while providing significant time savings plus imaging information that could be of further use in <em>in vivo</em> studies. The main advantages, features and drawbacks observed for UF 2D FLEX are briefly discussed.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100096"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3266172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of structure and functionality of porous materials","authors":"Manuel I. Velasco ,&nbsp;María Belén Franzoni ,&nbsp;Fabián Vaca Chávez ,&nbsp;Rodolfo H. Acosta","doi":"10.1016/j.jmro.2023.100099","DOIUrl":"https://doi.org/10.1016/j.jmro.2023.100099","url":null,"abstract":"<div><p>Nuclear magnetic resonance is widely used to probe the dynamics of fluids confined in porous media, where structural and functional properties of complex systems can be determined. The application includes a large variety of research or industrial areas such as medicine, gas and oil extraction, soil studies, the development of materials for drug delivery, and catalysis, among many other applications. This review covers the use of different NMR experiments applied to study the liquid/surface interaction, mobility, tortuosity, pore connectivity, and exchange phenomena in different porous matrixes. This article, included in the special issue devoted to NMR in Latin America, provides a review of the most applied techniques and a summary of different applications carried out at the Universidad Nacional de Córdoba in Argentina.</p></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"14 ","pages":"Article 100099"},"PeriodicalIF":2.624,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3135448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}