Reproducibility of absolute quantification of adenosine triphosphate and inorganic phosphate in the liver with localized 31P-magnetic resonance spectroscopy at 3-T using different coils.

Concentrations of the key metabolites of hepatic energy metabolism, adenosine triphosphate (ATP) and inorganic phosphate (Pi), can be altered in metabolic disorders such as diabetes mellitus. 31Phosphorus (31P)-magnetic resonance spectroscopy (MRS) is used to noninvasively measure hepatic metabolites, but measuring their absolute molar concentrations remains challenging. This study employed a 31P-MRS method based on the phantom replacement technique for quantifying hepatic 31P-metabolites on a 3-T clinical scanner. Two surface coils with different size and geometry were used to check for consistency in terms of repeatability and reproducibility and absolute concentrations of metabolites. Day-to-day (n = 8) and intra-day (n = 6) reproducibility was tested in healthy volunteers. In the day-to-day study, mean absolute concentrations of γ-ATP and Pi were 2.32 ± 0.24 and 1.73 ± 0.26 mM (coefficient of variation [CV]: 7.3% and 8.8%) for the single loop, and 2.32 ± 0.42 and 1.73 ± 0.27 mM (CVs 6.7% and 10.6%) for the quadrature coil, respectively. The intra-day study reproducibility using the quadrature coil yielded CVs of 4.7% and 6.8% for γ-ATP and Pi without repositioning, and 6.3% and 7.1% with full repositioning of the volunteer. The results of the day-to-day data did not differ between coils and visits. Both coils robustly yielded similar results for absolute concentrations of hepatic 31P-metabolites. The current method, applied with two different surface coils, can be readily utilized in long-term and interventional studies. In comparison with the single loop coil, the quadrature coil also allows measurements at a greater distance between the coil and liver, which is relevant for studying people with obesity.

Salivary Metabolites in Patients with Mucopolysaccharidosis

ABSTRACT Objective: To identify the salivary metabolites profile of Mucopolysaccharidosis (MPS) types I, II, IV, and VI patients. Material and Methods: The participants were asked to refrain from eating and drinking for one hour before sampling, performed between 7:30 and 9:00 a.m. Samples were centrifuged at 10.000 × g for 60 min at 4°C, and the supernatants (500µl) were stored at −80°C until NMR analysis. The salivary proton nuclear magnetic resonance (1H-NMR) spectra were acquired in a 500 MHz spectrometer, and TOCSY experiments were used to confirm and assign metabolites. Data were analyzed descriptively. Results: Differences in salivary metabolites were found among MPS types and the control, such as lactate, propionate, alanine, and N-acetyl sugar. Understanding these metabolite changes may contribute to precision medicine and early detection of mucopolysaccharidosis and its monitoring. Conclusion: The composition of low molecular weight salivary metabolites of mucopolysaccharidosis subjects may present specific features compared to healthy controls.

A hybrid strategy combining solution NMR spectroscopy and isothermal titration calorimetry to characterize protein-nanodisc interaction.

NMR is a powerful tool for characterizing intermolecular interactions at atomic resolution. However, the nature of the complex interactions of membrane-binding proteins makes it difficult to elucidate the interaction mechanisms. Here, we demonstrated that structural and thermodynamic analyses using solution NMR spectroscopy and isothermal titration calorimetry (ITC) can clearly detect a specific interaction between the pleckstrin homology (PH) domain of ceramide transport protein (CERT) and phosphatidylinositol 4-monophosphate (PI4P) embedded in the lipid nanodisc, and distinguish the specific interaction from nonspecific interactions with the bulk surface of the lipid nanodisc. This NMR-ITC hybrid strategy provides detailed characterization of protein-lipid membrane interactions.

Nuclear magnetic resonance immunoassay of tetanus antibodies based on the displacement of magnetic nanoparticles.

A nuclear magnetic resonance (NMR) immunoassay based on the application of carbon-coated iron nanoparticles conjugated with recognition molecules was designed. The principle of the assay is that ELISA plates are coated with a capture element, and then an analyte is added and detected by conjugating the magnetic nanoparticles with recognition molecules. Afterwards, the elution solution (0.1-M sodium hydroxide) is added to displace the magnetic nanoparticles from the well surfaces into the solution. The detached magnetic nanoparticles reduce transverse relaxation time (T2) values of protons from the surrounding solution. A portable NMR relaxometer is used to measure the T2. Magnetic nanoparticles conjugated with streptavidin, monoclonal antibodies, and protein G were applied for the detection of biotinylated albumin, prostate-specific antigen, and IgG specific to tetanus toxoid (TT). The limit of detection of anti-TT IgG was 0.08-0.12 mIU/mL. The reproducibility of the assay was within the acceptable range (CV < 7.4%). The key novelty of the immunoassay is that the displacement of the nanoparticles from the solid support by the elution solution allows the advantages of the solid phase assay to be combined with the sensitive detection of the T2 changes in a volume of liquid.

Characteristics of Starch Extracted from the Stem of Pineapple Plant (Ananas comosus) - an Agro Waste from Pineapple Farms

Abstract The present study focused on the use of pineapple plant stem, which is an agro-waste, for the production of starch (11.08 % ± 0.77). Characters were studied using X-ray diffraction, nuclear magnetic resonance spectroscopy (NMR), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and rheological methods. The granular size of stem starch was comparatively smaller than corn starch granules. The X-ray diffraction data revealed that stem starch has an A-type crystal structure. The molecular structure was similar to those obtained for native starches, which is confirmed by NMR and FTIR. The gelatinization temperature was observed to be higher than corn starch and rheological studies revealed; stem starch is more viscous than corn starch. The purity analysis showed that the harmful heavy metals were in negligible quantity and the tested pesticides were absent. This could make this a good source of starch for food industries. Results revealed that this agro-waste has a high potential for the production of good quality starch.

An integrated RF-receive/B0-shim array coil boosts performance of whole-brain MR spectroscopic imaging at 7 T.

Metabolic imaging of the human brain by in-vivo magnetic resonance spectroscopic imaging (MRSI) can non-invasively probe neurochemistry in healthy and disease conditions. MRSI at ultra-high field (≥ 7 T) provides increased sensitivity for fast high-resolution metabolic imaging, but comes with technical challenges due to non-uniform B0 field. Here, we show that an integrated RF-receive/B0-shim (AC/DC) array coil can be used to mitigate 7 T B0 inhomogeneity, which improves spectral quality and metabolite quantification over a whole-brain slab. Our results from simulations, phantoms, healthy and brain tumor human subjects indicate improvements of global B0 homogeneity by 55%, narrower spectral linewidth by 29%, higher signal-to-noise ratio by 31%, more precise metabolite quantification by 22%, and an increase by 21% of the brain volume that can be reliably analyzed. AC/DC shimming provide the highest correlation (R2 = 0.98, P = 0.001) with ground-truth values for metabolite concentration. Clinical translation of AC/DC and MRSI is demonstrated in a patient with mutant-IDH1 glioma where it enables imaging of D-2-hydroxyglutarate oncometabolite with a 2.8-fold increase in contrast-to-noise ratio at higher resolution and more brain coverage compared to previous 7 T studies. Hence, AC/DC technology may help ultra-high field MRSI become more feasible to take advantage of higher signal/contrast-to-noise in clinical applications.

Analytical and Structural Studies for the Investigation of Oxidative Stress in Guanine Oligonucleotides.

DNA damage plays a decisive role in epigenetic effects. The detection and analysis of DNA damages, like the most common change of guanine (G) to 8-oxo-7,8-dihydroguanine (OG), is a key factor in cancer research. It is especially true for G quadruplex structure (GQ), which is one of the best-known examples of a non-canonical DNA arrangement. In the present work, we provided an overview on analytical methods in connection with the detection of OG in oligonucleotides with GQ-forming capacity. Focusing on the last five years, novel electrochemical tools, like dedicated electrodes, were overviewed, as well as different optical methods (fluorometric assays, resonance light scattering or UV radiation) along with hyphenated detection and structural analysis methods (CD, NMR, melting temperature analysis and nanopore detection) were also applied for OG detection. Additionally, GQ-related computational simulations were also summarized. All these results emphasize that OG detection and the analysis of the effect of its presence in higher ordered structures like GQ is still a state-of-the-art research line with continuously increasing interest.

µ-NMR at the point of care testing.

NMR shows strong analytical capability for obtaining molecular information on materials and is used in a variety of fields. Micro-NMR (µNMR) is mainly based on low-field NMR (LF-NMR), which makes NMR detection portable and inexpensive. Point-of-care testing (POCT) has gradually become an area of major concern, and scientists have made much progress in applying µNMR systems for POCT. To the best of our knowledge, this is the first review of the latest development in miniaturization of µNMR systems. Then, we discuss cutting-edge µNMR-based applications in POCT and the outlook for future developments.

Multi-vendor standardized sequence for edited magnetic resonance spectroscopy.

Spectral editing allows direct measurement of low-concentration metabolites, such as GABA, glutathione (GSH) and lactate (Lac), relevant for understanding brain (patho)physiology. The most widely used spectral editing technique is MEGA-PRESS, which has been diversely implemented across research sites and vendors, resulting in variations in the final resolved edited signal. In this paper, we describe an effort to develop a new universal MEGA-PRESS sequence with HERMES functionality for the major MR vendor platforms with standardized RF pulse shapes, durations, amplitudes and timings. New RF pulses were generated for the universal sequence. Phantom experiments were conducted on Philips, Siemens, GE and Canon 3 T MRI scanners using 32-channel head coils. In vivo experiments were performed on the same six subjects on Philips and Siemens scanners, and on two additional subjects, one on GE and one on Canon scanners. On each platform, edited MRS experiments were conducted with the vendor-native and universal MEGA-PRESS sequences for GABA (TE = 68 ms) and Lac editing (TE = 140 ms). Additionally, HERMES for GABA and GSH was performed using the universal sequence at TE = 80 ms. The universal sequence improves inter-vendor similarity of GABA-edited and Lac-edited MEGA-PRESS spectra. The universal HERMES sequence yields both GABA- and GSH-edited spectra with negligible levels of crosstalk on all four platforms, and with strong agreement among vendors for both edited spectra. In vivo GABA+/Cr, Lac/Cr and GSH/Cr ratios showed relatively low variation between scanners using the universal sequence. In conclusion, phantom and in vivo experiments demonstrate successful implementation of the universal sequence across all four major vendors, allowing editing of several metabolites across a range of TEs.

Isotopic Labeling of Eukaryotic Membrane Proteins for NMR Studies of Interactions and Dynamics.

Membrane proteins, and especially G-protein coupled receptors (GPCRs), are increasingly important targets of structural biology studies due to their involvement in many biomedically critical pathways in humans. These proteins are often highly dynamic and thus benefit from studies by NMR spectroscopy in parallel with complementary crystallographic and cryo-EM analyses. However, such studies are often complicated by a range of practical concerns, including challenges in preparing suitably isotopically labeled membrane protein samples, large sizes of protein/detergent or protein/lipid complexes, and limitations on sample concentrations and stabilities. Here we describe our approach to addressing these challenges via the use of simple eukaryotic expression systems and modified NMR experiments, using the human adenosine A2A receptor as an example. Protocols are provided for the preparation of U-2H (13C,1H-Ile δ1)-labeled membrane proteins from overexpression in the methylotrophic yeast Pichia pastoris, as well as techniques for studying the fast ns-ps sidechain dynamics of the methyl groups of such samples. We believe that, with the proper optimization, these protocols should be generalizable to other GPCRs and human membrane proteins.

DNP NMR of biomolecular assemblies.

Dynamic Nuclear Polarization (DNP) is an effective approach to alleviate the inherently low sensitivity of solid-state NMR (ssNMR) under magic angle spinning (MAS) towards large-sized multi-domain complexes and assemblies. DNP relies on a polarization transfer at cryogenic temperatures from unpaired electrons to adjacent nuclei upon continuous microwave irradiation. This is usually made possible via the addition in the sample of a polarizing agent. The first pioneering experiments on biomolecular assemblies were reported in the early 2000s on bacteriophages and membrane proteins. Since then, DNP has experienced tremendous advances, with the development of extremely efficient polarizing agents or with the introduction of new microwaves sources, suitable for NMR experiments at very high magnetic fields (currently up to 900 MHz). After a brief introduction, several experimental aspects of DNP enhanced NMR spectroscopy applied to biomolecular assemblies are discussed. Recent demonstration experiments of the method on viral capsids, the type III and IV bacterial secretion systems, ribosome and membrane proteins are then described.

Nuclear magnetic resonance-based metabolomics approach to evaluate preventive and therapeutic effects of Gastrodia elata Blume on chronic atrophic gastritis.

Chronic atrophic gastritis (CAG) is one of the most common digestive system diseases worldwide which defined by WHO as initial step of cancer. Gastrodia elata Blume (GEB) is a traditional herbal with multiple pharmacological activities which was widely used in Asian countries. This study aims to explore the preventive and therapeutical effects of Gastrodia elata Blume on auto-immune induced CAG in rats. Tissues of stomachs were collected and submitted to 1H NMR-based metabolomics analysis and histopathological inspection. The biochemical indexes of MDA, SOD, GSH, NO and XOD were measured. Gastrodia elata Blume could apparently ameliorate the damaged gastric glands and the biochemical parameters, enhance gastric acid secretion, and significantly relieve the inflammation of the stomach. Orthogonal signal correction-partial least squares-discriminant analysis (OSC-PLS-DA) of NMR profiles and correlation network analysis revealed that Gastrodia elata Blume could effectively treat CAG via regulating energy and purine metabolisms, and by anti-oxidation and anti-inflammation effects.

A comparison of coil combination strategies in 3D multi-channel MRSI reconstruction for patients with brain tumors.

The goal of this study was to find the most robust algorithm for a phase-sensitive coil combination of 3D single-cycle and lactate-edited, multi-channel H-1 point-resolved spectroscopy (PRESS) localized echo planar spectroscopic imaging (EPSI) data for clinical applications in the brain. Data were acquired over 5-10 minutes at 3T using 8- or 32-channel array coils. Peak referencing with residual water and N-acetyl-aspartate, first-point phasing, generalized least squared (GLS) and whitened singular-value decomposition (WSVD) combination algorithms were evaluated relative to unsuppressed water with data from a phantom, six volunteers and 55 patients with brain tumors. Comparison metrics were signal-to-noise ratio, coefficient of variance and percent signal increase. Where residual water was present, using it as a reference peak for phasing and weighting factors from an imaging calibration scan gave the best overall performance. Greater improvement was seen for large selected volumes (>720 cm3 ) and for the 32-channel array (25%) compared with the 8-channel array (19%). Applying voxel-by-voxel phase corrections produced a larger increase in performance for the 32- versus 8-channel coil. We conclude that, for clinically relevant 3D H-1 PRESS localized EPSI studies, the most robust technique employed individual phase maps generated from high residual water and individual amplitude maps generated from calibration scans.

Wireless amplified NMR detector for improved visibility of image contrast in heterogeneous lesions.

To demonstrate the capability of a wireless amplified NMR detector (WAND) to improve the visibility of lesion heterogeneity without the use of exogenous contrast agents, a cylindrically symmetric WAND was constructed to sensitively detect and simultaneously amplify MR signals emitted from adjacent tissues. Based on a two-leg high-pass birdcage coil design, this WAND could be activated by a pumping field aligned along the main field (B0 ), without perturbing MR signal reception. Compared with an equivalent pair of external detectors, the WAND could achieve more than 10-fold gain for immediately adjacent regions. Even for regions with 3.4 radius distance separation from the detector's cylindrical center, the WAND was at least 1.4 times more sensitive than an equivalent pair of surface arrays or at least twice as sensitive as a single-sided external surface detector. When the WAND was inserted into a rat's rectum to observe adjacent tumors implanted beneath the mucosa, it could enhance the detection sensitivity of lesion regions, and thus enlarge the observable signal difference between heterogeneous tissues and clearly identify lesion boundaries as continuous lines in the intensity gradient profile. Hyperintense regions observable by the WAND existed due to higher levels of blood supply, which was indicated by a similar pattern of signal enhancement after contrast agent administration. By better observing the endogenous signal contrast, the endoluminal WAND could characterize lesions without the use of exogenous contrast agents, and thus reduce contrast-induced toxicity.

Radicular pain caused by Schmorl's node: a case report / Dor radicular causada por nódulo de Schmorl: relato de caso

Abstract Schmorl's node a focal herniation of intervertebral disc through the end plate into the vertebral body. Most of the established Schmorl's nodes are quiescent. However, disc herniation into the vertebral marrow can cause low back pain by irritating a nociceptive system. Schmorl's node induced radicular pain is a very rare condition. Some cases of Schmorl's node which generated low back pain or radicular pain were treated by surgical methods. In this article, authors reported a rare case of a patient with radicular pain cause by Schmorl's node located at the inferior surface of the 5th lumbar spine. The radicular pain was alleviated by serial 5th lumbar transforaminal epidural blocks. Transforaminal epidural block is suggested as first conservative option to treat radicular pain due to herniation of intervertebral disc. Therefore, non-surgical treatment such as transforaminal epidural block can be considered a first treatment option for radicular pain caused by Schmorl's node.

Resumo O nódulo de Schmörl (NS) é a herniação focal do disco intervertebral através da placa terminal para dentro do corpo vertebral. A maioria dos nódulos de Schmörl já estabelecidos é quiescente. Porém, a hérnia de disco na medula vertebral pode causar dor lombar quando afeta um sistema nociceptivo. A dor radicular induzida por NS é uma condição muito rara. Alguns casos de NS que causaram dor lombar ou radicular foram tratados com procedimentos cirúrgicos. Neste artigo, relatamos o caso raro de um paciente com dor radicular causada por NS localizado na superfície inferior da quinta vértebra lombar (L5). A dor radicular foi atenuada mediante uma série de bloqueios peridurais transforaminais no nível L5. O bloqueio epidural transforaminal (BET) foi sugerido como primeira opção conservadora para tratar a dor radicular devido à herniação do disco intervertebral. Portanto, um tratamento não cirúrgico como o BET pode ser considerado como uma primeira opção de tratamento da dor radicular causada por NS.

[Measurement Accuracy of Fat and Iron Deposits in the Liver Using 1H-MRS (HISTO)].

1H-MRS, which is a method of measuring fat and iron deposits in the liver, has a single voxel spectroscopy imaging method called high-speed T2-corrected multiecho (HISTO) based on the STEAM method. If HISTO measurement accuracy is high, it will be one of the biomarkers, so the measurement accuracy was examined. We imaged a self-made phantom simulating a known amount of fat and iron deposition in the liver. A regression analysis of HISTO-measured values for hepatic fat phantom was performed. In addition, regression analysis was performed on the hepatic iron phantom for the R2 values obtained from the T2 values measurement and the actually measured value of the HISTO. From the regression analysis, the correlation coefficients were 0.999, 0.992 and 0.977, respectively. The measurement accuracy of HISTO is high, and the reliability of the obtained fat and iron deposit value is high.

Economic Burden of Selected Diagnostic Imaging Methods in Oral Cancer

Objective: To analyse of proportion and economic burden of selected diagnostic imaging methods of oral cancer according to quarters and average percentage differences in the Slovak population in the period 2016-2017. Material and Methods: In this descriptive study, the data were retrieved from the information system of the largest public health insurance company on our request, which archives the cost and proportion of diagnostic imaging methods of oral cancer in Slovak population. It was evaluated 48,995 of selected diagnostic imaging methods (Computed Tomography [CT], Magnetic Resonance Imaging [MRI] and X-Ray) in the period 2016-2017. Results: The most frequently used diagnostic imaging method of oral cancer was magnetic resonance imaging method every quarters in 2016 and 2017 (53.7-54.7%) with slightly increasing trend in period 2016-2017. Mean economic burden of selected diagnostic imaging methods of oral cancer were 1,974,900€ for MRI method, 598,187€ for CT method and 5,394€ for RTG method in 2017. Decreasing trend of economic burden of diagnostic imaging method was found in MRI method and CT method in period 2016-2017. Conclusion: Our economic burden study provides a useful source for public health professional and clinicians in better understanding the economic burden of diagnostic methods in oral cancer.

Comparison of the analytical methods (solid state NMR, FT-IR, PXRD) in the analysis of the solid drug forms with low concentration of an active ingredient - 17-ß-estradiol case.

The application of various techniques (FT-IR, PXRD, ssNMR) in the analysis of solid dosage forms with low concentration of an API (17-ß-estradiol hemihydrate, EBHH) was tested. PXRD analysis of Estrofem Mite tablets (EMT) confirmed the presence of the main crystalline excipient, α-lactose monohydrate. In the PXRD pattern of EMT the strong background from polycrystalline excipients, i.e. hydroxypropylmethylcellulose and corn starch was observed. FT-IR spectra were characterized by the broad peaks in the 3000-3600cm-1 region of the OH stretching modes coming from multiple hydrogen bonds that are present in the structures of the excipients (α-lactose monohydrate, corn starch) and API. The only technique which unambiguously confirmed the presence of an API in the EMT was solid state NMR. Despite the tabletting process each of the EMT component retained its characteristic features like relaxation time and T1ρI. Due to the possibility of the manipulation in the experimental registration parameters like recycle delay (RD), evolution time (τ) and contact time (CT) it was possible to perform multiple experiments on the same sample of EMT. The most valuable were the inversion recovery CP experiments in which, by setting the proper values of τ, it was possible to selectively observe the signals of the chosen component of the drug formulation. In this study the great potential of solid state NMR in the analysis of solid dosage forms, as the unique technique that combines the possibility of selective observation of the chosen signals with the non destructive character that enables further analysis of the same sample, was confirmed.

Comparison between Short and Long Echo Time Magnetic Resonance Spectroscopic Imaging at 3T and 7T for Evaluating Brain Metabolites in Patients with Glioma.

Three-dimensional proton magnetic resonance spectroscopic imaging (MRSI) is a powerful non-invasive tool for characterizing spatial variations in metabolic profiles for patients with glioma. Metabolic parameters obtained using this technique have been shown to predict treatment response, disease progression, and transformation to a more malignant phenotype. The availability of ultra-high-field MR systems has the potential to improve the characterization of metabolites. The purpose of this study was to compare the metabolite profiles acquired with conventional long echo time (TE) MRSI at 3T with those obtained with short TE MRSI at 3T and 7T in patients with glioma. The data acquisition parameters were optimized separately for each echo time and field strength to obtain volumetric coverage within clinically feasible data acquisition times of 5-10 min. While a higher field strength did provide better detection of metabolites with overlapping peaks, spatial coverage was reduced and the use of inversion recovery to reduce lipid precluded the detection of lipid in regions of necrosis. For serial evaluation of large, heterogeneous lesions, the use of 3T short TE MRSI may thus be preferred. Despite the limited number of metabolites that it is able to detect, the use of 3T long TE MRSI gives the best contrast in choline/N-acetyl aspartate between normal appearing brain and tumor and also allows the separate detection of lactate and lipid. It may therefore be preferred for serial evaluation of patients with high-grade glioma and for detection of malignant transformation in patients with low-grade glioma.