-
1.
Solid-state NMR analysis of crystalline and amorphous Indomethacin: An experimental protocol for full resonance assignments.
Lu, X, Xu, W, Hanada, M, Jermain, SV, Williams, RO, Su, Y
Journal of pharmaceutical and biomedical analysis. 2019;:47-55
Abstract
Solid-state NMR (ssNMR) analysis of pharmaceutical materials relies on accurate resonance assignments. The relatively low sensitivity and resolution from the natural abundance and solid-state nature of the active pharmaceutical ingredient (API) and particularly the disordered structure of amorphous forms result in the ambiguous identification of NMR peaks. In this study, a robust protocol for unambiguously assigning 13C and 1H chemical shifts of crystalline and amorphous APIs has been established and successfully tested on γ-polymorph indomethacin. Specifically, one-dimensional (1D) 13C-edited experiments, two-dimensional (2D) 13C-detected homo- and heteronuclear correlations, and 2D 1H-detected techniques under ultrafast magic angle spinning (MAS) provide enhanced resolution to identify overlapped 13C resonances and assign confidently the 1H chemical shifts. This experimental strategy allows us to assign particularly those carbons and protons either unassigned or ambiguous identified due to the technical challenges in previous literature. Besides, the chemical shift comparison between the crystalline and amorphous forms can potentially report the molecular packing variations.
-
2.
Understanding Protein Function Through an Ensemble Description: Characterization of Functional States by 19F NMR.
Di Pietrantonio, C, Pandey, A, Gould, J, Hasabnis, A, Prosser, RS
Methods in enzymology. 2019;:103-130
Abstract
Protein function is a consequence of a complex and dynamic equilibrium between allosterically coupled functional states. However, it is often difficult to distinguish the representative members of an ensemble by spectroscopic means. 19F NMR is particularly useful in this regard owing to the sensitivity of its chemical shift to subtle differences in environment. Here, we address aspects of 19F NMR relevant to the study of ensembles. In particular, we discuss current trends toward: (1) 19F-reporters that can be biosynthetically incorporated into proteins, (2) Approaches to chemical tagging of proteins by 19F reporters, (3) Improving delineation of states by 19F NMR, (4) Distinguishing states by (19F NMR-based) topology measurements that focus on solvent exposure and hydrophobicity, (5) Relaxation experiments and simple approaches to delineating states in fast and slow exchange, (6) Extending resolution of states by 19F NMR, and (7) Validating 19F NMR spectroscopy by computational methods. Many of these advances are demonstrated through recent 19F NMR studies of a homodimeric enzyme, fluoroacetate dehalogenase.
-
3.
Elucidating ligand-bound structures of membrane proteins using solid-state NMR spectroscopy.
Elkins, MR, Hong, M
Current opinion in structural biology. 2019;:103-109
-
-
Free full text
-
Abstract
Magic-angle-spinning (MAS) solid-state NMR spectroscopy is a versatile technique to elucidate functionally important protein-ligand interactions in lipid membranes. Here, we review recent solid-state NMR studies of membrane protein interactions with cholesterol, lipids, transported substrates, and peptide ligands. These studies are conducted in synthetic or native lipid bilayers to provide an accurate environment for ligand binding. The solid-state NMR approaches include multinuclear detection to gain comprehensive structural information, distance measurements to locate ligand-binding sites, and dynamic nuclear polarization and 1H detection to enhance spectral sensitivity. These studies provide novel insights into the mechanisms of virus budding, virus entry into cells, transmembrane signaling, substrate transport, antibacterial action, and many other biological processes.
-
4.
Lost in translation: lessons learned from the "demise" of MRSI of the prostate.
Westphalen, AC
Abdominal radiology (New York). 2019;(9):3185-3187
Abstract
At times, technologies fail for reasons other than an inability to deliver on their promises. The iconic Blackberry, for example, was once coined "Research in Motion", sold tens of millions of units, and then "disappeared" from the market because it did not accompany the new trends in design. Promising technologies may also "disappear" in the medical field. What follows is the tale of the rise and fall of proton magnetic resonance spectroscopic imaging (1H MRSI) of the prostate.
-
5.
High-resolution pure shift NMR spectroscopy offers better metabolite discrimination in food quality analysis.
Bo, Y, Feng, J, Xu, J, Huang, Y, Cai, H, Cui, X, Dong, J, Ding, S, Chen, Z
Food research international (Ottawa, Ont.). 2019;:108574
Abstract
PSYCHE homonuclear decoupling, a prominent pure shift NMR method, is successfully applied to adulteration discrimination of honey and geographical originality identification of tea. Effects of homonuclear couplings are efficiently suppressed, producing resolution-enhanced spectra. The pair wise honey and tea samples are well separated in OPLS-DA models with high predictability. Due to the well-resolved and accurate assignment of singlet resonances after decoupling, PSYCHE is advantageous in the identification of differential components and accurate quantification of compound concentrations presented by enhanced volcano and Beeswarm plots of honey samples, while the analysis of NOESY is easily interfered by overlapped resonances, which is further proved by the STOCSY analysis, displaying the spectral stability and reproducibility. Experimental results show that PSYCHE can improve the spectral resolution of natural complex products such as honey and tea and be combined with multivariate statistical analysis and serve as a supplementary technique to the standard methods, especially for samples systems composed by a few high-content compounds.
-
6.
Systematic Review: Noninvasive Assessments of Intestinal Failure-Associated Liver Disease in the Adult Population.
Huijbers, A, Koggel, LM, Bronkhorst, C, Verheij, J, Wanten, GJA
JPEN. Journal of parenteral and enteral nutrition. 2019;(5):615-626
Abstract
Chronic intestinal failure (CIF) patients are at risk for developing intestinal failure-associated liver disease (IFALD), which can progress to end-stage liver disease. Liver biopsy is the current reference standard to diagnose and monitor IFALD. However, due to its associated complications, biopsy is an unattractive tool in this respect. Our aim was to assess the evidence regarding non-invasive assessment of IFALD in the adult population and provide ideas to take this field further. We searched the PubMed, EMBASE and Web of Science databases in accordance with the PRISMA guideline. We included studies in the adult/mixed intestinal failure population, performing non-invasive diagnostic assessment of IFALD and using liver biopsy, 1H-MRS or MRI-PDFF as reference. Quality of the included studies was assessed using the QUADAS-2 tool. Four studies were included, assessing two serum (vitamin B12, FGF21) and two imaging tests (Fibroscan, CAUS). Three used liver biopsy as reference, all according to a different histological scoring system. One used 1H-MRS as reference. Vitamin B12 did not correlate with liver injury, Fibroscan did not correlate with fibrosis, but with cholestasis. FGF21 correlated with steatosis grade. Several CAUS parameters correlated with the degree of steatosis assessed by 1H-MRS. In conclusion, three tests show promise to non-invasively assess IFALD, but the limited data do not justify conclusions on the diagnostic value of the tested biomarkers. Hence, additional studies are needed. Identification of and validation for grading and staging of clinically relevant histomorphological parameters of IFALD is also crucial and a conceptual study set up is provided.
-
7.
Assessment of reproducibility and biological variability of fasting and postprandial plasma metabolite concentrations using 1H NMR spectroscopy.
Li-Gao, R, Hughes, DA, le Cessie, S, de Mutsert, R, den Heijer, M, Rosendaal, FR, Willems van Dijk, K, Timpson, NJ, Mook-Kanamori, DO
PloS one. 2019;(6):e0218549
Abstract
INTRODUCTION It is crucial to understand the factors that introduce variability before applying metabolomics to clinical and biomarker research. OBJECTIVES We quantified technical and biological variability of both fasting and postprandial metabolite concentrations measured using 1H NMR spectroscopy in plasma samples. METHODS In the Netherlands Epidemiology of Obesity study (n = 6,671), 148 metabolite concentrations (101 metabolites belonging to lipoprotein subclasses) were measured under fasting and postprandial states (150 minutes after a mixed liquid meal). Technical variability was evaluated among 265 fasting and 851 postprandial samples, with the identical blood plasma sample being measured twice by the same laboratory protocol. Biological reproducibility was assessed by measuring 165 individuals twice across time for evaluation of short- (<6 months) and long-term (>3 years) biological variability. Intra-class coefficients (ICCs) were used to assess variability. The ICCs of the fasting metabolites were compared with the postprandial metabolites using two-sided paired Wilcoxon test separately for short- and long-term measurements. RESULTS Both fasting and postprandial metabolite concentrations showed high technical reproducibility using 1H NMR spectroscopy (median ICC = 0.99). Postprandial metabolite concentrations revealed slightly higher ICC scores than fasting ones in short-term repeat measures (median ICC in postprandial and fasting metabolite concentrations 0.72 versus 0.67, Wilcoxon p-value = 8.0×10-14). Variability did not increase further in a long-term repeat measure, with median ICC in postprandial of 0.64 and in fasting metabolite concentrations 0.66. CONCLUSION Technical reproducibility is excellent. Biological reproducibility of postprandial metabolite concentrations showed a less or equal variability than fasting metabolite concentrations over time.
-
8.
Cerebral Ketones Detected by 3T MR Spectroscopy in Patients with High-Grade Glioma on an Atkins-Based Diet.
Berrington, A, Schreck, KC, Barron, BJ, Blair, L, Lin, DDM, Hartman, AL, Kossoff, E, Easter, L, Whitlow, CT, Jung, Y, et al
AJNR. American journal of neuroradiology. 2019;(11):1908-1915
Abstract
BACKGROUND AND PURPOSE Ketogenic diets are being explored as a possible treatment for several neurological diseases, but the physiologic impact on the brain is unknown. The objective of this study was to evaluate the feasibility of 3T MR spectroscopy to monitor brain ketone levels in patients with high-grade gliomas who were on a ketogenic diet (a modified Atkins diet) for 8 weeks. MATERIALS AND METHODS Paired pre- and post-ketogenic diet MR spectroscopy data from both the lesion and contralateral hemisphere were analyzed using LCModel software in 10 patients. RESULTS At baseline, the ketone bodies acetone and β-hydroxybutyrate were nearly undetectable, but by week 8, they increased in the lesion for both acetone (0.06 ± 0.03 ≥ 0.27 ± 0.06 IU, P = .005) and β-hydroxybutyrate (0.07 ± 0.07 ≥ 0.79 ± 0.32 IU, P = .046). In the contralateral brain, acetone was also significantly increased (0.041 ± 0.01 ≥ 0.16 ± 0.04 IU, P = .004), but not β-hydroxybutyrate. Acetone was detected in 9/10 patients at week 8, and β-hydroxybutyrate, in 5/10. Acetone concentrations in the contralateral brain correlated strongly with higher urine ketones (r = 0.87, P = .001) and lower fasting glucose (r = -0.67, P = .03). Acetoacetate was largely undetectable. Small-but-statistically significant decreases in NAA were also observed in the contralateral hemisphere at 8 weeks. CONCLUSIONS This study suggests that 3T MR spectroscopy is feasible for detecting small cerebral metabolic changes associated with a ketogenic diet, provided that appropriate methodology is used.
-
9.
The potentiality of NMR-based metabolomics in food science and food authentication assessment.
Consonni, R, Cagliani, LR
Magnetic resonance in chemistry : MRC. 2019;(9):558-578
Abstract
In the last years, there was an increasing interest on nuclear magnetic resonance (NMR) spectroscopy, whose applications experienced an exponential growth in several research fields, particularly in food science. NMR was initially developed as the elective technique for structure elucidation of single molecules and nowadays is playing a dominant role in complex mixtures investigations. In the era of the "omics" techniques, NMR was rapidly enrolled as one of the most powerful methods to approach metabolomics studies. Its use in analytical routines, characterized by rapid and reproducible measurements, would provide the identification of a wide range of chemical compounds simultaneously, disclosing sophisticated frauds or addressing the geographical origin, as well as revealing potential markers for other authentication purposes. The great economic value of high-quality or guaranteed foods demands highly detailed characterization to protect both consumers and producers from frauds. The present scenario suggests metabolomics as the privileged approach of modern analytical studies for the next decades. The large potentiality of high-resolution NMR techniques is here presented through specific applications and using different approaches focused on the authentication process of some foods, like tomato paste, saffron, honey, roasted coffee, and balsamic and traditional balsamic vinegar of Modena, with a particular focus on geographical origin characterization, ageing determination, and fraud detection.
-
10.
Clinical and (31)P magnetic resonance spectroscopy characterization of patients with critical limb ischemia before and after autologous cell therapy.
Dubský, M, Šedivý, P, Němcová, A, Drobný, M, Hazdrová, J, Fejfarová, V, Bém, R, Jirkovská, A, Dezortová, M, Hájek, M
Physiological research. 2019;(4):559-566
Abstract
Autologous cell therapy (ACT) is a new treatment method for diabetic patients with critical limb ischemia (CLI) not eligible for standard revascularization. After intramuscular injection of bone marrow-derived mononuclear cells local arteriogenesis in the ischemic tissue occurs. Studies assessing visualization of this therapeutic vasculogenesis after ACT by novel imaging techniques are lacking. The aim of our study was to assess the effect of ACT on possible metabolic changes and perfusion of critically ischemic limbs using (31)P magnetic resonance spectroscopy ( (31)P MRS) and its possible correlation with changes of transcutaneous oxygen pressure (TcPO(2)). Twenty-one patients with diabetes and no-option CLI treated by ACT in our foot clinic over 8 years were included in the study. TcPO(2) as well as rest (phosphocreatine, adenosine triphosphate and inorganic phosphate) and dynamic (mitochondrial capacity and phosphocreatine recovery time) (31)P-MRS parameters were evaluated at baseline and 3 months after cell treatment. TcPO(2) increased significantly after 3 months compared with baseline (from 22.4±8.2 to 37.6±13.3 mm Hg, p=0.0002). Rest and dynamic (31)P MRS parameters were not significantly different after ACT in comparison with baseline values. Our study showed a significant increase of TcPO(2) on the dorsum of the foot after ACT. We did not observe any changes of rest or dynamic (31)P MRS parameters in the area of the proximal calf where the cell suspension has been injected into.