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https://www.readbyqxmd.com/read/29330386/on-the-detection-of-cerebral-metabolic-depression-in-experimental-traumatic-brain-injury-using-chemical-exchange-saturation-transfer-cest-weighted-mri
#1
Tsang-Wei Tu, Wael G Ibrahim, Neekita Jikaria, Jeeva P Munasinghe, Jaclyn A Witko, Dima A Hammoud, Joseph A Frank
Metabolic abnormalities are commonly observed in traumatic brain injury (TBI) patients exhibiting long-term neurological deficits. This study investigated the feasibility and reproducibility of using chemical exchange saturation transfer (CEST) MRI to detect cerebral metabolic depression in experimental TBI. Phantom and in vivo CEST experiments were conducted at 9.4 Tesla to optimize the selective saturation for enhancing the endogenous contrast-weighting of the proton exchanges over the range of glucose proton chemical shifts (glucoCEST) in the resting rat brain...
January 12, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29322559/cest-dixon-for-human-breast-lesion-characterization-at-3-t-a-preliminary-study
#2
Shu Zhang, Stephen Seiler, Xinzeng Wang, Ananth J Madhuranthakam, Jochen Keupp, Emily E Knippa, Robert E Lenkinski, Elena Vinogradov
PURPOSE: Chemical exchange saturation transfer (CEST) MRI for breast lesion characterization is promising. However, artifacts are prone to develop in breast CEST imaging as a result of strong lipid signals. The aims of the study are (i) to develop and validate the CEST-Dixon imaging sequence for simultaneous water-fat separation and B0 mapping; and (ii) use the CEST-Dixon method to characterize suspicious lesions in patients undergoing percutaneous biopsy. METHODS: The gradient-echo multi-echo Dixon acquisition is used to create fat-free CEST and B0 maps...
January 10, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29313159/improved-differentiation-of-low-grade-and-high-grade-gliomas-and-detection-of-tumor-proliferation-using-apt-contrast-fitted-from-z-spectrum
#3
Jiaxuan Zhang, Wenzhen Zhu, Rongwen Tain, Xiaohong Joe Zhou, Kejia Cai
PURPOSE: The purpose of the study is to demonstrate the value of quantitative amide proton transfer (APT) imaging for differentiating glioma grades and detecting tumor proliferation. PROCEDURES: This study included 32 subjects with 16 low-grade gliomas (LGG) and 16 high-grade gliomas (HGG) confirmed by histopathology. Chemical exchange saturation transfer (CEST) magnetic resonance imaging with APT weighting was performed on a 3 T scanner. After B0 correction, Z-spectra were fitted with Lorentzian functions corresponding to the upfield semi-solid magnetization transfer and nuclear overhauser enhancement (MT&NOE) effect, the direct saturation (DS) effect, and the downfield APT effect centered at around - 1...
January 8, 2018: Molecular Imaging and Biology: MIB: the Official Publication of the Academy of Molecular Imaging
https://www.readbyqxmd.com/read/29276882/deciphering-the-dynamic-interaction-profile-of-an-intrinsically-disordered-protein-by-nmr-exchange-spectroscopy
#4
Elise Delaforge, Jaka Kragelj, Laura Tengo, Andrés Palencia, Sigrid Milles, Guillaume Bouvignies, Nicola Salvi, Martin Blackledge, Malene Ringkjøbing Jensen
Intrinsically disordered proteins (IDPs) display a large number of interaction modes including folding-upon-binding, binding without major structural transitions or binding through highly dynamic, so-called fuzzy, complexes. The vast majority of experimental information about IDP binding modes have been inferred from crystal structures of proteins in complex with short peptides of IDPs. However, crystal structures provide a mainly static view of the complexes and do not give information about the conformational dynamics experienced by the IDP in the bound state...
December 25, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29274298/time-resolved-monitoring-of-enzyme-activity-with-ultrafast-hyper-cest-spectroscopy
#5
Jörg Döpfert, Matthias Schnurr, Martin Kunth, Honor May Rose, Andreas Hennig, Leif Schröder
We propose a method to dynamically monitor the progress of an enzymatic reaction using NMR of hyperpolarized 129 Xe in a host-guest system. It is based on a displacement assay originally designed for fluorescence experiments that exploits the competitive binding of the enzymatic product on the one hand and a reporter dye on the other hand to a supramolecular host. Recently, this assay has been successfully transferred to NMR, using xenon as a reporter, cucurbit[6]uril as supramolecular host, and Hyper-CEST as detection technique...
December 23, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29233200/first-rescue-under-the-rubble-the-medical-aid-in-the-first-hours-after-the-earthquake-in-amatrice-italy-on-august-24-2016
#6
Angelo Geremia Blasetti, Emiliano Petrucci, Vincenza Cofini, Barbara Pizzi, Paolo Scimia, Tullio Pozone, Stefano Necozione, Pierfrancesco Fusco, Franco Marinangeli
Specific Event Identifiers a. Event Type: Earthquake measuring 6.2 (SD=0.016) on the moment magnitude; b. Event Onset: August 24, 2016 - 03:36:32 CEST (01:36 UTC); c. Location of Event: Central Italy, in the town of Amatrice; d. Geographic Coordinates: latitude (DMS): 42°37'45.77″N; longitude (DMS): 13°17'18.14″E; elevation: 955 meters above sea-level; e. Dates: August 24, 2016 at 4:48 AM; f. Response Type: Medical Relief. ABSTRACT: On August 24, 2016, an earthquake hit the town of Amatrice (Italy)...
December 13, 2017: Prehospital and Disaster Medicine
https://www.readbyqxmd.com/read/29193448/increased-cest-specificity-for-amide-and-fast-exchanging-amine-protons-using-exchange-dependent-relaxation-rate
#7
Xiao-Yong Zhang, Feng Wang, Junzhong Xu, Daniel F Gochberg, John C Gore, Zhongliang Zu
Chemical exchange saturation transfer (CEST) imaging of amides at 3.5 ppm and fast-exchanging amines at 3 ppm provides a unique means to enhance the sensitivity of detection of, for example, proteins/peptides and neurotransmitters, respectively, and hence can provide important information on molecular composition. However, despite the high sensitivity relative to conventional magnetic resonance spectroscopy (MRS), in practice, CEST often has relatively poor specificity. For example, CEST signals are typically influenced by several confounding effects, including direct water saturation (DS), semi-solid non-specific magnetization transfer (MT), the influence of water relaxation times (T1w ) and nearby overlapping CEST signals...
November 29, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/29193288/characterization-of-tumor-vascular-permeability-using-natural-dextrans-and-cest-mri
#8
Yuguo Li, Yuan Qiao, Hanwei Chen, Renyuan Bai, Verena Staedtke, Zheng Han, Jiadi Xu, Kannie W Y Chan, Nirbhay Yadav, Jeff W M Bulte, Shibin Zhou, Peter C M van Zijl, Guanshu Liu
PURPOSE: To investigate the use of natural dextrans as nano-sized chemical exchange saturation transfer (CEST) MRI probes for characterizing size-dependent tumor vascular permeability. METHODS: Dextrans of different molecular weight (10, 70, 150, and 2000 kD) were characterized for their CEST contrast. Mice (N = 5) bearing CT26 subcutaneous colon tumors were injected intravenously with 10 kD (D10, 6 nm) and 70 kD (D70, 12 nm) dextran at a dose of 375 mg/kg...
November 28, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29191206/optimized-cest-cardiovascular-magnetic-resonance-for-assessment-of-metabolic-activity-in-the-heart
#9
Zhengwei Zhou, Christopher Nguyen, Yuhua Chen, Jaime L Shaw, Zixin Deng, Yibin Xie, James Dawkins, Eduardo Marbán, Debiao Li
BACKGROUND: Previous studies have linked cardiac dysfunction to loss of metabolites in the creatine kinase system. Chemical exchange saturation transfer (CEST) is a promising metabolic cardiovascular magnetic resonance (CMR) imaging technique and has been applied in the heart for creatine mapping. However, current limitations include: (a) long scan time, (b) residual cardiac and respiratory motion, and (c) B0 field variations induced by respiratory motion. An improved CEST CMR technique was developed to address these problems...
November 30, 2017: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/29171604/sensitivity-enhanced-detection-of-non-labile-proton-and-carbon-nmr-spectra-on-water-resonances
#10
Mihajlo Novakovic, Ricardo P Martinho, Gregory L Olsen, Michael S Lustig, Lucio Frydman
Chemical exchange saturation transfer (CEST) experiments enhance the NMR signals of labile protons by continuously transferring these protons' saturation to an abundant solvent pool like water. The present study expands these principles by fusing into these experiments homonuclear isotropic mixing sequences, enabling the water-enhanced detection of non-exchangeable species. Further opportunities are opened by the addition of coupling-mediated heteronuclear polarization transfers, which then impose on the water resonance a saturation stemming from non-labile heteronuclear species like (13)C...
November 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29169778/-15-n-cest-data-and-traditional-model-free-analysis-capture-fast-internal-dynamics-of-dj-1
#11
Jonathan Catazaro, Tessa Andrews, Nicole M Milkovic, Jiusheng Lin, Austin J Lowe, Mark A Wilson, Robert Powers
Previous studies have shown that relaxation parameters and fast protein dynamics can be quickly elucidated from (15)N-CEST experiments [1]. Longitudinal R1 and transverse R2 values were reliably derived from fitting of CEST profiles. Herein we show that (15)N-CEST experiments and traditional modelfree analysis provide the internal dynamics of three states of human protein DJ-1 at physiological temperature. The chemical exchange profiles show the absence of a minor state conformation and, in conjunction with (1)H-(15)N NOEs, show increased mobility...
November 20, 2017: Analytical Biochemistry
https://www.readbyqxmd.com/read/29154463/establishing-upper-limits-on-neuronal-activity-evoked-ph-changes-with-apt-cest-mri-at-7-t
#12
Vitaliy Khlebnikov, Jeroen C W Siero, Alex A Bhogal, Peter R Luijten, Dennis W J Klomp, Hans Hoogduin
PURPOSE: To detect neuronal activity-evoked pH changes by amide proton transfer-chemical exchange saturation transfer (APT-CEST) MRI at 7 T. METHODS: Three healthy subjects participated in the study. A low-power 3-dimensional APT-CEST sequence was optimized through the Bloch-McConnell equations. pH sensitivity of the sequence was estimated both in phantoms and in vivo. The feasibility of pH-functional MRI was tested in Bloch-McConnell-simulated data using the optimized sequence...
November 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29143921/dichloroacetate-induced-intracellular-acidification-in-glioblastoma-in-vivo-detection-using-aacid-cest-mri-at-9-4%C3%A2-tesla
#13
Mohammed Albatany, Alex Li, Susan Meakin, Robert Bartha
Intracellular pH (pHi) plays an important role in the maintenance of normal cell function, and is maintained within a narrow range by the activity of transporters located at the plasma membrane. Modulation of tumor pHi may influence proliferation, apoptosis, chemotherapy resistance, and thermosensitivity. Chemical exchange saturation transfer (CEST) is a novel MRI contrast mechanism that is dependent on cellular pH. Amine and amide concentration-independent detection (AACID) is a recently developed CEST contrast method that is intracellular pH (pHi) weighted...
November 16, 2017: Journal of Neuro-oncology
https://www.readbyqxmd.com/read/29133469/an-invisible-ubiquitin-conformation-is-required-for-efficient-phosphorylation-by-pink1
#14
Christina Gladkova, Alexander F Schubert, Jane L Wagstaff, Jonathan N Pruneda, Stefan M V Freund, David Komander
The Ser/Thr protein kinase PINK1 phosphorylates the well-folded, globular protein ubiquitin (Ub) at a relatively protected site, Ser65. We previously showed that Ser65 phosphorylation results in a conformational change in which Ub adopts a dynamic equilibrium between the known, common Ub conformation and a distinct, second conformation wherein the last β-strand is retracted to extend the Ser65 loop and shorten the C-terminal tail. We show using chemical exchange saturation transfer (CEST) nuclear magnetic resonance experiments that a similar, C-terminally retracted (Ub-CR) conformation also exists at low population in wild-type Ub...
November 13, 2017: EMBO Journal
https://www.readbyqxmd.com/read/29119369/clinical-importance-of-temporal-bone-features-for-the-efficacy-of-contrast-enhanced-sonothrombolysis-a-retrospective-analysis-of-the-nor-sass-trial
#15
Vojtech Novotny, Aliona Nacu, Christopher E Kvistad, Annette Fromm, Gesche F Neckelmann, Andrej N Khanevski, Haakon Tobro, Ulrike Waje-Andreassen, Halvor Naess, Lars Thomassen, Nicola Logallo
Contrast-enhanced sonothrombolysis (CEST) seems to be a safe and promising treatment in acute ischemic stroke. It remains unknown if temporal bone features may influence the efficacy of CEST. We investigated the association between different temporal bone features on admission computed tomography (CT) scan and the outcome in acute ischemic stroke patients included in the randomized Norwegian Sonothrombolysis in Acute Stroke Study (NOR-SASS). Patients diagnosed as stroke mimics and those with infratentorial stroke or with incorrect insonation were excluded...
November 8, 2017: Translational Stroke Research
https://www.readbyqxmd.com/read/29111410/the-z-spectrum-from-human-blood-at-7t
#16
Simon M Shah, Olivier E Mougin, Andrew J Carradus, Nicolas Geades, Richard Dury, William Morley, Penny A Gowland
Chemical Exchange Saturation Transfer (CEST) has been used to assess healthy and pathological tissue in both animals and humans. However, the CEST signal from blood has not been fully assessed. This paper presents the CEST and nuclear Overhauser enhancement (NOE) signals detected in human blood measured via z-spectrum analysis. We assessed the effects of blood oxygenation levels, haematocrit, cell structure and pH upon the z-spectrum in ex vivo human blood for different saturation powers at 7T. The data were analysed using Lorentzian difference (LD) model fitting and AREX (to compensate for changes in T1), which have been successfully used to study CEST effects in vivo...
October 27, 2017: NeuroImage
https://www.readbyqxmd.com/read/29083166/enantiomeric-recognition-of-d-and-l-lactate-by-cest-with-the-aid-of-a-paramagnetic-shift-reagent
#17
Lei Zhang, André F Martins, Piyu Zhao, Michael Tieu, David Esteban-Gómez, Gregory T McCandless, Carlos Platas-Iglesias, A Dean Sherry
A previous report demonstrated that EuDO3A could be used as an NMR shift reagent for imaging extracellular lactate produced by cancer cells using CEST imaging. In this work, a series of heptadentate macrocyclic YbDO3A-trisamide complexes with δ-chiral carbons in the three pendant side-arms were examined as shift reagents for lactate detection. High resolution (1)H NMR spectra and DFT calculations provided evidence for the formation of stereoselective lactate·YbDO3A-trisamide complexes each with a different CEST signature...
November 17, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29068044/contrast-enhanced-sonothrombolysis-in-acute-ischemic-stroke-patients-without-intracranial-large-vessel-occlusion
#18
C E Kvistad, A Nacu, V Novotny, N Logallo, U Waje-Andreassen, H Naess, L Thomassen
BACKGROUND: Contrast-enhanced sonothrombolysis (CEST) leads to a more rapid recanalization in acute ischemic stroke caused by intracranial large-vessel occlusion (LVO). Animal studies have shown that CEST also may be safe and efficient in treating the ischemic microcirculation in the absence of LVO. The exact mechanism behind this treatment effect is not known. We aimed to assess safety and efficacy of CEST in acute ischemic stroke patients included in the Norwegian Sonothrombolysis in Acute Stroke Study (NOR-SASS) without LVO on admission CT angiography (CTA)...
February 2018: Acta Neurologica Scandinavica
https://www.readbyqxmd.com/read/29038382/protonation-of-carboxyl-groups-in-eudota-tetraamide-complexes-results-in-catalytic-prototropic-exchange-and-quenching-of-the-cest-signal
#19
Lei Zhang, Osasere M Evbuomwan, Michael Tieu, Piyu Zhao, Andre F Martins, A Dean Sherry
The CEST properties of EuDOTA-tetraamide complexes bearing pendant carboxylate and carboxyl ethyl esters were measured as a function of pH. The CEST signal from the Eu(3+)-bound water molecule decreased in intensity between pH 8.5 and 4.5 while the proton exchange rates (kex) increased over this same pH range. In comparison, the CEST signal in the corresponding carboxyl ester derivatives was nearly constant. Both observations are consistent with stepwise protonation of the four carboxylic acid groups over this same pH range...
November 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29030880/direct-saturation-corrected-chemical-exchange-saturation-transfer-mri-of-glioma-simplified-decoupling-of-amide-proton-transfer-and-nuclear-overhauser-effect-contrasts
#20
Iris Yuwen Zhou, Enfeng Wang, Jerry S Cheung, Dongshuang Lu, Yang Ji, Xiaoan Zhang, Giulia Fulci, Phillip Zhe Sun
PURPOSE: Chemical exchange saturation transfer (CEST) MRI has shown promise in tissue characterization in diseases like stroke and tumor. However, in vivo CEST imaging such as amide proton transfer (APT) MRI is challenging because of concomitant factors such as direct water saturation, macromolecular magnetization transfer, and nuclear overhauser effect (NOE), which lead to a complex contrast in the commonly used asymmetry analysis (MTRasym). Here, we propose a direct saturation-corrected CEST (DISC-CEST) analysis for simplified decoupling and quantification of in vivo CEST effects...
October 13, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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