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Chemical exchange saturation transfer

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https://www.readbyqxmd.com/read/28915341/-31-p-magnetic-resonance-fingerprinting-for-rapid-quantification-of-creatine-kinase-reaction-rate-in-vivo
#1
Charlie Y Wang, Yuchi Liu, Shuying Huang, Mark A Griswold, Nicole Seiberlich, Xin Yu
The purpose of this work was to develop a (31) P spectroscopic magnetic resonance fingerprinting (MRF) method for fast quantification of the chemical exchange rate between phosphocreatine (PCr) and adenosine triphosphate (ATP) via creatine kinase (CK). A (31) P MRF sequence (CK-MRF) was developed to quantify the forward rate constant of ATP synthesis via CK ( kfCK), the T1 relaxation time of PCr ( T1PCr), and the PCr-to-ATP concentration ratio ( MRPCr). The CK-MRF sequence used a balanced steady-state free precession (bSSFP)-type excitation with ramped flip angles and a unique saturation scheme sensitive to the exchange between PCr and γATP...
September 15, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28912676/chemical-exchange-saturation-transfer-mri-signal-loss-of-the-substantia-nigra-as-an-imaging-biomarker-to-evaluate-the-diagnosis-and-severity-of-parkinson-s-disease
#2
Chunmei Li, Min Chen, Xuna Zhao, Rui Wang, Haibo Chen, Wen Su, Shuhua Li, Baohui Lou, Guodong Song, Shuai Zhang, Jintao Zhang, Jinyuan Zhou
The early diagnosis of Parkinson's disease (PD) and the accurate evaluation of disease severity are crucial for intervention and treatment in PD patients. In this study, we applied chemical exchange saturation transfer (CEST) imaging to patients at different stages of PD and explored the clinical value of the CEST signal loss of the substantia nigra as an imaging biomarker of PD. The measured CEST signal intensities (including amide proton transfer-weighted or APTw, and total CEST or CESTtotal) of the substantia nigra in PD patients showed a significantly decreased tendency with PD progression...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28880278/preparation-of-biogenic-gas-vesicle-nanostructures-for-use-as-contrast-agents-for-ultrasound-and-mri
#3
Anupama Lakshmanan, George J Lu, Arash Farhadi, Suchita P Nety, Martin Kunth, Audrey Lee-Gosselin, David Maresca, Raymond W Bourdeau, Melissa Yin, Judy Yan, Christopher Witte, Dina Malounda, F Stuart Foster, Leif Schröder, Mikhail G Shapiro
Gas vesicles (GVs) are a unique class of gas-filled protein nanostructures that are detectable at subnanomolar concentrations and whose physical properties allow them to serve as highly sensitive imaging agents for ultrasound and MRI. Here we provide a protocol for isolating GVs from native and heterologous host organisms, functionalizing these nanostructures with moieties for targeting and fluorescence, characterizing their biophysical properties and imaging them using ultrasound and MRI. GVs can be isolated from natural cyanobacterial and haloarchaeal host organisms or from Escherichia coli expressing a heterologous GV gene cluster and purified using buoyancy-assisted techniques...
October 2017: Nature Protocols
https://www.readbyqxmd.com/read/28862349/z-spectrum-appearance-and-interpretation-in-the-presence-of-fat-influence-of-acquisition-parameters
#4
Shu Zhang, Jochen Keupp, Xinzeng Wang, Ivan Dimitrov, Ananth J Madhuranthakam, Robert E Lenkinski, Elena Vinogradov
PURPOSE: Chemical exchange saturation transfer (CEST) MRI is increasingly evolving from brain to body applications. One of the known problems in the body imaging is the presence of strong lipid signals. Although their influence on the CEST effect is acknowledged, there was no study that focuses on the interplay among echo time, fat fraction, and Z-spectrum. This study strives to address these points, with the emphasis on the application in the breast. METHODS: Z-spectra were simulated in phase and out of phase of the main fat peak at -3...
September 1, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28856067/application-of-dendrimer-based-nanoparticles-in-glioma-imaging
#5
Sunalee Gonawala, Meser M Ali
Dendritic polymers or dendrimers present an alternate template for the development of nanoparticulate-based drug delivery and imaging systems. The smaller size (~7-12 nm) of dendrimers have the advantage over the other particles, because its smaller size can possibly improve tumor penetration and the inclusion of tumor specific drug release mechanisms. A Paramagnetic Chemical Exchange Saturation Transfer (PARACEST) MRI contrast agent, Eu-DOTA-Gly4 or a clinical relevant Gd-DOTA was conjugated on the surface of a G5 PAMAM dendrimer...
June 2017: Journal of Nanomedicine & Nanotechnology
https://www.readbyqxmd.com/read/28846825/use-of-fluorine-pseudocontact-shifts-to-characterize-the-protein-ligand-interaction-mode-in-the-limit-of-nmr-intermediate-exchange
#6
Jia Gao, E Liang, Rongsheng Ma, Fudong Li, Yiyang Liu, Jiuyang Liu, Ling Jiang, Conggang Li, Haiming Dai, Jihui Wu, Xuncheng Su, Wei He, Ke Ruan
The characterization of protein-ligand interaction modes becomes recalcitrant in the NMR intermediate exchange regime as the interface resonances are broadened beyond detection. Here, we determined the 19F low-populated bound-state pseudocontact shifts (PCSs) of mono- and di-fluorinated inhibitors of the BRM bromodomain using a highly-skewed protein/ligand ratio. The bound-state 19F PCSs were retrieved from 19F chemical exchange saturation transfer (CEST) in the presence of the lanthanide-labeled protein, which was termed the 19F PCS-CEST approach...
August 28, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28841302/molecular-mechanism-for-the-epigallocatechin-gallate-induced-toxic-to-nontoxic-remodeling-of-a%C3%AE-oligomers
#7
Rashik Ahmed, Bryan VanSchouwen, Naeimeh Jafari, Xiaodan Ni, Joaquin Ortega, Giuseppe Melacini
(-)-Epigallocatechin gallate (EGCG) effectively reduces the cytotoxicity of the Alzheimer's disease β-amyloid peptide (Aβ) by remodeling seeding-competent Aβ oligomers into off-pathway seeding-incompetent Aβ assemblies. However, the mechanism of EGCG-induced remodeling is not fully understood. Here we combine (15)N and (1)H dark-state exchange saturation transfer (DEST), relaxation, and chemical shift projection NMR analyses with fluorescence, dynamic light scattering, and electron microscopy to elucidate how EGCG remodels Aβ oligomers...
August 25, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28841293/heading-toward-macromolecular-and-nanosized-bioresponsive-mri-probes-for-successful-functional-imaging
#8
Goran Angelovski
The quest for bioresponsive or smart contrast agents (SCAs) in molecular imaging, in particular magnetic resonance imaging (MRI), is progressively increasing since they allow for the monitoring of essential biological processes on molecular and cellular levels in a dynamic fashion. These are offshoot molecules of common contrast agents that are sensitive to biochemical changes in their environment, capable of reporting on such changes by inducing MRI signal alteration. Various mechanistic approaches and different types of SCAs have been developed in order to visualize desired processes, using diverse imaging protocols and methods...
August 25, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28812315/metabolite-cycled-steam-and-semi-laser-localization-for-mr-spectroscopy-of-the-human-brain-at-9-4t
#9
Ioannis-Angelos Giapitzakis, Tingting Shao, Nikolai Avdievich, Ralf Mekle, Roland Kreis, Anke Henning
PURPOSE: Metabolite cycling (MC) is an MRS technique for the simultaneous acquisition of water and metabolite spectra that avoids chemical exchange saturation transfer effects and for which water may serve as a reference signal or contain additional information in functional or diffusion studies. Here, MC was developed for human investigations at ultrahigh field. METHODS: MC-STEAM and MC-semi-LASER are introduced at 9.4T with an optimized inversion pulse and elaborate coil setup...
August 15, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28792646/clinical-applications-of-chemical-exchange-saturation-transfer-cest-mri
#10
Kyle M Jones, Alyssa C Pollard, Mark D Pagel
Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) has been developed and employed in multiple clinical imaging research centers worldwide. Selective radiofrequency (RF) saturation pulses with standard 2D and 3D MRI acquisition schemes are now routinely performed, and CEST MRI can produce semiquantitative results using magnetization transfer ratio asymmetry (MTRasym ) analysis while accounting for B0 inhomogeneity. Faster clinical CEST MRI acquisition methods and more quantitative acquisition and analysis routines are under development...
August 9, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28746744/enzyme-responsive-lipocest-agents-assessment-of-mmp-2-activity-by-measuring-the-intra-liposomal-water-1h-nmr-resonance-shift
#11
Giuseppe Ferrauto, Enza Di Gregorio, Marta Ruzza, Valeria Catanzaro, Sergio Padovan, Silvio Aime
Mobile proton containing solutes can be detected by MRI via Chemical Exchange Saturation Transfer(CEST)method. The CEST sensitivity is dramatically enhanced by using, as exchanging protons, the water molecules confined inside liposomes, properly shifted by a paramagnetic Shift Reagent. The chemical shift of the intraliposomal water resonance(δIL) is affected by the overall shape of the supramolecular system. Herein, it is shown that δIL of a spherical LipoCEST acts as a sensitive reporter of the distribution of Streptavidin proteins anchored at the Liposomes'surface by biotinylated phospholipids...
July 26, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28741638/-19-f-cest-imaging-probes-for-metal-ion-detection
#12
Qiaoli Peng, Yaping Yuan, Huaibin Zhang, Shaowei Bo, Yu Li, Shizhen Chen, Zhigang Yang, Xin Zhou, Zhong-Xing Jiang
For detecting metal ions with (19)F chemical exchange saturation transfer magnetic resonance imaging ((19)F CEST MRI), a class of novel fluorinated chelators with diverse fluorine contents and chelation properties were conveniently synthesized on gram scales. Among them, a DTPA-derived chelator with high sensitivity and selectivity was identified as a novel (19)F CEST imaging probe for simultaneously detecting multiple metal ions.
August 2, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28736875/assessment-of-unilateral-ureter-obstruction-with-multi-parametric-mri
#13
Feng Wang, Keiko Takahashi, Hua Li, Zhongliang Zu, Ke Li, Junzhong Xu, Raymond C Harris, Takamune Takahashi, John C Gore
PURPOSE: Quantitative multi-parametric MRI (mpMRI) methods may allow the assessment of renal injury and function in a sensitive and objective manner. This study aimed to evaluate an array of MRI methods that exploit endogenous contrasts including relaxation rates, pool size ratio (PSR) derived from quantitative magnetization transfer (qMT), chemical exchange saturation transfer (CEST), nuclear Overhauser enhancement (NOE), and apparent diffusion coefficient (ADC) for their sensitivity and specificity in detecting abnormal features associated with kidney disease in a murine model of unilateral ureter obstruction (UUO)...
July 24, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28733991/ph-sensitive-amide-proton-transfer-effect-dominates-the-magnetization-transfer-asymmetry-contrast-during-acute-ischemia-quantification-of-multipool-contribution-to-in-vivo-cest-mri
#14
Yin Wu, Iris Yuwen Zhou, Dongshuang Lu, Emiri Manderville, Eng H Lo, Hairong Zheng, Phillip Zhe Sun
PURPOSE: To determine the origins of in vivo magnetization transfer asymmetry contrast during acute ischemic stroke, particularly in the diffusion lesion, perfusion lesion, and their mismatch using a middle cerebral artery occlusion rat model of acute stroke. METHODS: Adult male Wistar rats underwent multiparametric MRI of diffusion, perfusion, T1 , and amide proton transfer (APT) imaging at 4.7 T following a middle cerebral artery occlusion procedure. A multipool Lorentzian model, including the nuclear Overhauser effect, magnetization transfer, direct water saturation, amine and amide chemical exchange saturation transfer effects, was applied for Z-spectrum fitting to determine the sources of in vivo magnetization transfer asymmetry following acute stroke...
July 21, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28726131/detection-of-enzyme-activity-and-inhibition-during-studies-in-solution-in-vitro-and-in-vivo-with-catalycest-mri
#15
Sanhita Sinharay, Edward A Randtke, Christine M Howison, Natalia A Ignatenko, Mark D Pagel
PURPOSE: The detection of enzyme activities and evaluation of enzyme inhibitors have been challenging with magnetic resonance imaging (MRI). To address this need, we have developed a diamagnetic, nonmetallic contrast agent and a protocol known as catalyCEST MRI that uses chemical exchange saturation transfer (CEST) to detect enzyme activity as well as enzyme inhibition. PROCEDURES: We synthesized a diamagnetic MRI contrast agent that has enzyme responsive and enzyme unresponsive CEST signals...
July 19, 2017: Molecular Imaging and Biology: MIB: the Official Publication of the Academy of Molecular Imaging
https://www.readbyqxmd.com/read/28719589/an-excited-state-underlies-gene-regulation-of-a-transcriptional-riboswitch
#16
Bo Zhao, Sharon L Guffy, Benfeard Williams, Qi Zhang
Riboswitches control gene expression through ligand-dependent structural rearrangements of the sensing aptamer domain. However, we found that the Bacillus cereus fluoride riboswitch aptamer adopts identical tertiary structures in solution with and without ligand. Using chemical-exchange saturation transfer (CEST) NMR spectroscopy, we revealed that the structured ligand-free aptamer transiently accesses a low-populated (∼1%) and short-lived (∼3 ms) excited conformational state that unravels a conserved 'linchpin' base pair to signal transcription termination...
September 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28714513/in-vivo-evaluation-of-tumour-acidosis-for-assessing-the-early-metabolic-response-and-onset-of-resistance-to-dichloroacetate-by-using-magnetic-resonance-ph-imaging
#17
Annasofia Anemone, Lorena Consolino, Laura Conti, Francesca Reineri, Federica Cavallo, Silvio Aime, Dario Livio Longo
Dichloroacetate (DCA) can reverse the glycolytic phenotype that is responsible of increased lactate production and extracellular pH acidification in cancer cells. Magnetic resonance imaging-chemical exchange saturation transfer (MRI-CEST) pH mapping is a novel non-invasive imaging approach that can measure in vivo extracellular tumour pH. We examined whether MRI-CEST pH mapping can monitor in vivo changes in tumour acidosis for assessing treatment response to DCA. Cell viability and extracellular pH were assessed in TS/A breast cancer cells treated with 1-10 mM DCA for 24 h in normoxia or hypoxia (1% O2) conditions...
August 2017: International Journal of Oncology
https://www.readbyqxmd.com/read/28709641/glucocest-magnetic-resonance-imaging-in%C3%A2-vivo-may-be-diagnostic-of-acute-renal-allograft-rejection
#18
Dominik Kentrup, Philipp Bovenkamp, Annika Busch, Katharina Schuette-Nuetgen, Helga Pawelski, Hermann Pavenstädt, Eberhard Schlatter, Karl-Heinz Herrmann, Jürgen R Reichenbach, Bettina Löffler, Barbara Heitplatz, Veerle Van Marck, Nirbhay N Yadav, Guanshu Liu, Peter C M van Zijl, Stefan Reuter, Verena Hoerr
Acute cellular renal allograft rejection (AR) frequently occurs after kidney transplantations. It is a sterile T-cell mediated inflammation leading to increased local glucose metabolism. Here we demonstrate in an allogeneic model of Brown Norway rat kidneys transplanted into uninephrectomized Lewis rats the successful implementation of the recently developed glucose chemical exchange saturation transfer (glucoCEST) magnetic resonance imaging. This technique is a novel method to assess and differentiate AR...
September 2017: Kidney International
https://www.readbyqxmd.com/read/28707688/probing-the-excited-state-chemical-shifts-and-exchange-parameters-by-nitrogen-decoupled-amide-proton-chemical-exchange-saturation-transfer-hn-dec-cest
#19
Qinglin Wu, Benjamin A Fenton, Jessica L Wojtaszek, Pei Zhou
CEST-NMR spectroscopy is a powerful tool for probing the conformational dynamics of macromolecules. We present a HN(dec)-CEST experiment that simplifies the relaxation matrix, reduces fitting parameters, and enhances signal resolution. Importantly, fitting of HN(dec)-CEST profiles enables robust extraction of exchange rates as well as excited-state chemical shifts and populations.
July 27, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28686805/a-generalized-ratiometric-chemical-exchange-saturation-transfer-cest-mri-approach-for-mapping-renal-ph-using-iopamidol
#20
Yin Wu, Iris Y Zhou, Takahiro Igarashi, Dario L Longo, Silvio Aime, Phillip Zhe Sun
PURPOSE: To extend the pH detection range of iopamidol-based ratiometric chemical exchange saturation transfer (CEST) MRI at sub-high magnetic field and establish quantitative renal pH MRI. METHODS: Chemical exchange saturation transfer imaging was performed on iopamidol phantoms with pH of 5.5 to 8.0 and in vivo on rat kidneys (n = 5) during iopamidol administration at a 4.7 T. Iopamidol CEST effects were described using a multipool Lorentzian model. A generalized ratiometric analysis was conducted by ratioing resolved iopamidol CEST effects at 4...
July 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
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