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https://www.readbyqxmd.com/read/29756286/rapid-and-quantitative-chemical-exchange-saturation-transfer-cest-imaging-with-magnetic-resonance-fingerprinting-mrf
#1
Ouri Cohen, Shuning Huang, Michael T McMahon, Matthew S Rosen, Christian T Farrar
PURPOSE: To develop a fast magnetic resonance fingerprinting (MRF) method for quantitative chemical exchange saturation transfer (CEST) imaging. METHODS: We implemented a CEST-MRF method to quantify the chemical exchange rate and volume fraction of the Nα -amine protons of L-arginine (L-Arg) phantoms and the amide and semi-solid exchangeable protons of in vivo rat brain tissue. L-Arg phantoms were made with different concentrations (25-100 mM) and pH (pH 4-6)...
May 13, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29753980/exploring-methods-to-expedite-the-recording-of-cest-datasets-using-selective-pulse-excitation
#2
Tairan Yuwen, Guillaume Bouvignies, Lewis E Kay
Chemical Exchange Saturation Transfer (CEST) has emerged as a powerful tool for studies of biomolecular conformational exchange involving the interconversion between a major, visible conformer and one or more minor, invisible states. Applications typically entail recording a large number of 2D datasets, each of which differs in the position of a weak radio frequency field, so as to generate a CEST profile for each nucleus from which the chemical shifts of spins in the invisible state(s) are obtained. Here we compare a number of band-selective CEST schemes for speeding up the process using either DANTE or cosine-modulated excitation approaches...
April 26, 2018: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29749579/in-vivo-detection-of-acute-intracellular-acidification-in-glioblastoma-multiforme-following-a-single-dose-of-cariporide
#3
Mohammed Albatany, Alex Li, Susan Meakin, Robert Bartha
Glioblastoma is an aggressive brain cancer that is very difficult to treat. Clinically, it is important to be able to distinguish aggressive from non-aggressive brain tumors. Previous studies have shown that some drugs can induce a rapid change in intracellular pH that could help to identify aggressive cancer. The sodium proton exchanger (NHE1) plays a significant role in maintaining pH balance in the tumor microenvironment. Cariporide is a sodium proton exchange inhibitor that is well tolerated by humans in cardiac applications...
May 10, 2018: International Journal of Clinical Oncology
https://www.readbyqxmd.com/read/29733378/assessing-the-predictability-of-idh-mutation-and-mgmt-methylation-status-in-glioma-patients-using-relaxation-compensated-multi-pool-cest-mri-at-7-0-tesla
#4
Daniel Paech, Johannes Windschuh, Johanna Oberhollenzer, Constantin Dreher, Felix Sahm, Jan-Eric Meissner, Steffen Goerke, Patrick Schuenke, Moritz Zaiss, Sebastian Regnery, Sebastian Bickelhaupt, Philipp Bäumer, Martin Bendszus, Wolfgang Wick, Andreas Unterberg, Peter Bachert, Mark Edward Ladd, Heinz-Peter Schlemmer, Alexander Radbruch
Background: Early identification of prognostic superior characteristics in glioma patients such as Isocitrate dehydrogenase(IDH)-mutation and O6-methylguanine-DNA-methyltransferase (MGMT) promotor methylation status is of great clinical importance. The study purpose was to investigate the non-invasive predictability of IDH-mutation status, MGMT promotor methylation, and differentiation of lower versus higher grade glioma (LGG vs. HGG) in newly-diagnosed patients employing relaxation-compensated multi-pool Chemical Exchange Saturation Transfer (CEST) magnetic resonance imaging (MRI) at 7...
May 4, 2018: Neuro-oncology
https://www.readbyqxmd.com/read/29727175/interaction-of-huntingtin-exon-1-peptides-with-lipid-based-micellar-nanoparticles-probed-by-solution-nmr-and-q-band-pulsed-epr
#5
Alberto Ceccon, Thomas Schmidt, Vitali Tugarinov, Samuel A Kotler, Charles D Schwieters, G Marius Clore
Lipid-based micellar nanoparticles promote aggregation of huntingtin exon-1 peptides. Here we characterize the interaction of two such peptides, httNTQ7 and httNTQ10 comprising the N-terminal amphiphilic domain of huntingtin followed by 7 and 10 glutamine repeats, respectively, with 8 nm lipid micelles using NMR chemical exchange saturation transfer (CEST), circular dichroism and pulsed Q-band EPR. Exchange between free and micelle-bound httNTQn peptides occurs on the millisecond time scale with a KD ~ 0.5-1 mM...
May 4, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29682499/paracest-agents-encapsulated-in-reverse-nano-assembled-capsules-racs-how-slow-molecular-tumbling-can-quench-cest-contrast
#6
Annah Farashishiko, Jacqueline R Slack, Mauro Botta, Mark Woods
Although paraCEST is a method with immense scope for generating image contrast in MRI, it suffers from the serious drawback of high detection limits. For a typical discrete paraCEST agent the detection limit is roughly an order of magnitude higher than that of a clinically used relaxation agent. One solution to this problem may be the incorporation of a large payload of paraCEST agents into a single macromolecular agent. Here we report a new synthetic method for accomplishing this goal: incorporating a large payload of the paraCEST agent DyDOTAM3+ into a Reverse Assembled nano-Capsule...
2018: Frontiers in Chemistry
https://www.readbyqxmd.com/read/29672976/dual-frequency-irradiation-cest-mri-of-endogenous-bulk-mobile-proteins
#7
Steffen Goerke, Johannes Breitling, Moritz Zaiss, Johannes Windschuh, Patrick Kunz, Patrick Schuenke, Daniel Paech, Dario L Longo, Karel D Klika, Mark E Ladd, Peter Bachert
A novel MRI contrast is proposed which enables the selective detection of endogenous bulk mobile proteins in vivo. Such a non-invasive imaging technique may be of particular interest for many diseases associated with pathological alterations of protein expression, such as cancer and neurodegenerative disorders. Specificity to mobile proteins was achieved by the selective measurement of intramolecular spin diffusion and the removal of semi-solid macromolecular signal components by a correction procedure. For this purpose, the approach of chemical exchange saturation transfer (CEST) was extended to a radiofrequency (RF) irradiation scheme at two different frequency offsets (dualCEST)...
April 19, 2018: NMR in Biomedicine
https://www.readbyqxmd.com/read/29663694/dramatic-decrease-in-cest-measurement-times-using-multi-site-excitation
#8
Tairan Yuwen, Lewis E Kay, Guillaume Bouvignies
Chemical exchange saturation transfer (CEST) has recently evolved into a powerful approach for studying sparsely populated, "invisible" protein states in slow exchange with a major, visible conformer. Central to the technique is the use of a weak, highly selective radio-frequency field that is applied at different frequency offsets in successive experiments, "searching" for minor state resonances. The recording of CEST profiles with enough points to ensure coverage of the entire spectrum at sufficient resolution can be time-consuming, especially for applications that require high static magnetic-fields or when small chemical shift differences between exchanging states must be quantified...
April 17, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29656880/fundamentals-of-functional-imaging-ii-emerging-mr-techniques-and-new-methods-of-analysis
#9
A Luna, T Martín Noguerol, L Alcalá Mata
Current multiparameter MRI protocols integrate structural, physiological, and metabolic information about cancer. Emerging techniques such as arterial spin-labeling (ASL), blood oxygen level dependent (BOLD), MR elastography, chemical exchange saturation transfer (CEST), and hyperpolarization provide new information and will likely be integrated into daily clinical practice in the near future. Furthermore, there is great interest in the study of tumor heterogeneity as a prognostic factor and in relation to resistance to treatment, and this interest is leading to the application of new methods of analysis of multiparametric protocols...
April 12, 2018: Radiología
https://www.readbyqxmd.com/read/29656510/robust-motion-correction-in-cest-imaging-exploiting-low-rank-approximation-of-the-z-spectrum
#10
Tobias Wech, Herbert Köstler
PURPOSE: To introduce and evaluate an image registration technique for robust quantification of CEST acquisitions corrupted by motion. METHODS: The proposed iterative algorithm exploits a low-rank approximation of the z-spectrum (LRAZ), to gradually separate the contrast variation due to saturation at different off-resonance frequencies and accompanying motion. This registration method was first tested in a creatine CEST analysis of a phantom with simulated rigid motion...
April 15, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29645309/hydrazo-cest-hydrazone-dependent-chemical-exchange-saturation-transfer-magnetic-resonance-imaging-contrast-agents
#11
Trina Dang, Mojmir Suchy, Yen Truong, Wendy Oakden, Wilfred Lam, Caitlin Lazurko, Glenn Facey, Greg Stanisz, Adam Shuhendler
The rapid formation of hydrazones under physiological conditions was exploited for the detection of aldehydes through chemical exchange saturation transfer magnetic resonance imaging (CEST-MRI). A metal-free, diamagnetic contrast agent derived from N-amino anthranilic acid was introduced, which selectively 'turned-on' upon hydrazone formation through an effect termed Hydrazo-CEST. While the hydrazine form of the probe produced no CEST-MRI signal enhancement, the formation of the aryl hydrazone resulted in >20% intensity decrease in the bulk water signal through the CEST effect, as measured by 300 MHz 1H NMR, 3T and 7T MRI...
April 12, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29626359/simultaneous-ph-sensitive-and-oxygen-sensitive-mri-of-human-gliomas-at-3-t-using-multi-echo-amine-proton-chemical-exchange-saturation-transfer-spin-and-gradient-echo-echo-planar-imaging-cest-sage-epi
#12
Robert J Harris, Jingwen Yao, Ararat Chakhoyan, Catalina Raymond, Kevin Leu, Linda M Liau, Phioanh L Nghiemphu, Albert Lai, Noriko Salamon, Whitney B Pope, Timothy F Cloughesy, Benjamin M Ellingson
PURPOSE: To introduce a new pH-sensitive and oxygen-sensitive MRI technique using amine proton CEST echo spin-and-gradient echo (SAGE) EPI (CEST-SAGE-EPI). METHODS: pH-weighting was obtained using CEST estimations of magnetization transfer ratio asymmetry (MTRasym ) at 3 ppm, and oxygen-weighting was obtained using R2' measurements. Glutamine concentration, pH, and relaxation rates were varied in phantoms to validate simulations and estimate relaxation rates. The values of MTRasym and R2' in normal-appearing white matter, T2 hyperintensity, contrast enhancement, and macroscopic necrosis were measured in 47 gliomas...
April 6, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29594656/glioblastoma-gbm-effects-on-quantitative-mri-of-contralateral-normal-appearing-white-matter
#13
Hatef Mehrabian, Wilfred W Lam, Sten Myrehaug, Arjun Sahgal, Greg J Stanisz
PURPOSE: The objective was to investigate (with quantitative MRI) whether the normal appearing white matter (NAWM) of glioblastoma (GBM) patients on the contralateral side (cNAWM) was different from NAWM of healthy controls. METHODS: Thirteen patients with newly diagnosed GBM and nine healthy age-matched controls were MRI-scanned with quantitative magnetization transfer (qMT), chemical exchange saturation transfer (CEST), and transverse relaxation time (T2 )-mapping...
March 28, 2018: Journal of Neuro-oncology
https://www.readbyqxmd.com/read/29588032/xenon-protein-interactions-characterization-by-x-ray-crystallography-and-hyper-cest-nmr
#14
Benjamin W Roose, Serge D Zemerov, Ivan J Dmochowski
The physiological activity of xenon has long been recognized, though the exact nature of its interactions with biomolecules remains poorly understood. Xe is an inert noble gas, but can act as a general anesthetic, most likely by binding internal hydrophobic cavities within proteins. Understanding Xe-protein interactions, therefore, can provide crucial insight regarding the mechanism of Xe anesthesia and potentially other general anesthetic agents. Historically, Xe-protein interactions have been studied primarily through X-ray crystallography and nuclear magnetic resonance (NMR)...
2018: Methods in Enzymology
https://www.readbyqxmd.com/read/29577382/mri-detection-of-bacterial-brain-abscesses-and-monitoring-of-antibiotic-treatment-using-baccest
#15
Jing Liu, Renyuan Bai, Yuguo Li, Verena Staedtke, Shuixing Zhang, Peter C M van Zijl, Guanshu Liu
PURPOSE: To develop a new MRI method to detect and characterize brain abscesses using the CEST contrast inherently carried by bacterial cells, namely bacCEST. METHODS: Bacteria S. aureus (ATCC #49775) and F98 and 9L glioma cells were injected stereotactically in the brains of F344 rats to form abscesses and tumors. The CEST signals of brain abscesses (n = 4) and tumors (n = 7) were acquired using 2 B1 values (i.e., 1 and 3 µT) and compared. The bacCEST signal of the brain abscesses in the rats (n = 3) receiving ampicillin (intraperitoneal injection 40 mg/kg twice daily) was acquired before, 4 and 10 days after the treatment...
March 25, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29568427/nanomolar-small-molecule-detection-using-a-genetically-encoded-129-xe-nmr-contrast-agent
#16
B W Roose, S D Zemerov, I J Dmochowski
Genetically encoded magnetic resonance imaging (MRI) contrast agents enable non-invasive detection of specific biomarkers in vivo . Here, we employed the hyper-CEST129 Xe NMR technique to quantify maltose (32 nM to 1 mM) through its modulation of conformational change and xenon exchange in maltose binding protein (MBP). Remarkably, no hyper-CEST signal was observed for MBP in the absence of maltose, making MBP an ultrasensitive "smart" contrast agent. The resonance frequency of129 Xe bound to MBP was greatly downfield-shifted (Δ δ = 95 ppm) from the129 Xe(aq) peak, which facilitated detection in E...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29567971/molecular-basis-of-binding-between-the-global-post-transcriptional-regulator-csra-and-the-t3ss-chaperone-cest
#17
Fei Ye, Fanli Yang, Ruijie Yu, Xi Lin, Jianxun Qi, Zhujun Chen, Yu Cao, Yuquan Wei, George F Gao, Guangwen Lu
The T3SS chaperone CesT is recently shown to interact with the post-transcriptional regulator CsrA to modulate post-attachment signaling in enteropathogenic and enterohemorrhagic Escherichia coli. The molecular basis of the CesT/CsrA binding, however, remains elusive. Here, we show that CesT and CsrA both created two ligand binding sites in their homodimers, forming irregular multimeric complexes in solution. Through construction of a recombinant CsrA-dimer (Re-CsrA) that contains a single CesT binding site, the atomic binding features between CesT and CsrA are delineated via the structure of the CesT/Re-CsrA complex...
March 22, 2018: Nature Communications
https://www.readbyqxmd.com/read/29545551/non-invasive-detection-of-adeno-associated-viral-gene-transfer-using-a-genetically-encoded-cest-mri-reporter-gene-in-the-murine-heart
#18
Shelby Meier, Assaf A Gilad, J Anthony Brandon, Chenghao Qian, Erhe Gao, Jose F Abisambra, Moriel Vandsburger
Research into gene therapy for heart failure has gained renewed interest as a result of improved safety and availability of adeno-associated viral vectors (AAV). While magnetic resonance imaging (MRI) is standard for functional assessment of gene therapy outcomes, quantitation of gene transfer/expression relies upon tissue biopsy, fluorescence or nuclear imaging. Imaging of gene expression through the use of genetically encoded chemical exchange saturation transfer (CEST)-MRI reporter genes could be combined with clinical cardiac MRI methods to comprehensively probe therapeutic gene expression and subsequent outcomes...
March 15, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29516549/cest-mri-studies-of-cells-loaded-with-lanthanide-shift-reagents
#19
Giuseppe Ferrauto, Enza Di Gregorio, Daniela Delli Castelli, Silvio Aime
PURPOSE: Magnetic resonance imaging has been used extensively to track in vivo implanted cells that have been previously labeled with relaxation enhancers. However, this approach is not suitable to track multiple cell populations, as it may lead to confounding results in case the contrast agent is released from the labeled cells. This paper demonstrates how the use of CEST agents can overcome these issues. After encapsulating paramagnetic lanthanide shift reagents, we may shift the absorption frequency of the intracellular water resonance (δIn ), thus generating frequency-encoding CEST responsive cells that can be visualized in the MR image by applying the proper RF irradiation...
March 7, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29509331/tandem-tyrosine-phosphosites-in-the-enteropathogenic-escherichia-coli-chaperone-cest-are-required-for-differential-type-iii-effector-translocation-and-virulence
#20
Cameron S Runte, Umang Jain, Landon J Getz, Sabrina Secord, Asaomi Kuwae, Akio Abe, Jason J LeBlanc, Andrew W Stadnyk, James B Kaper, Anne-Marie Hansen, Nikhil A Thomas
Enteropathogenic Escherichia coli (EPEC) use a type 3 secretion system (T3SS) for injection of effectors into host cells and intestinal colonization. Here, we demonstrate that the multicargo chaperone CesT has two strictly conserved tyrosine phosphosites, Y152 and Y153 that regulate differential effector secretion in EPEC. Conservative substitution of both tyrosine residues to phenylalanine strongly attenuated EPEC type 3 effector injection into host cells, and limited Tir effector mediated intimate adherence during infection...
March 6, 2018: Molecular Microbiology
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