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Chemical exchange saturation transfer

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https://www.readbyqxmd.com/read/28644017/spectrally-undiscerned-isomers-might-lead-to-erroneous-determination-of-water-exchange-rates-of-paracest-eu-iii-agents
#1
Nevenka Cakić, Ben Tickner, Moritz Zaiss, David Esteban-Gómez, Carlos Platas-Iglesias, Goran Angelovski
We report a detailed study of the solution structure and water exchange rate of a Eu(III) complex with the cyclen-based ligand L(1), containing (S)-2-(2-acetamido)-3-(4-(trifluoromethyl)phenyl)propanoate pendant arms at positions 1 and 7 of the cyclen ring and acetylglycinate pendants at positions 4 and 10. The EuL(1) complex was characterized by a combination of NMR and luminescence spectroscopy and density functional theory (DFT) calculations. The chemical exchange saturation transfer (CEST) spectra obtained at different temperatures and saturation powers present a CEST signal attributed to the coordinated water molecule...
June 23, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28627877/detection-and-quantification-of-hydrogen-peroxide-in-aqueous-solutions-using-chemical-exchange-saturation-transfer-cest
#2
David Ryoo, Xiang Xu, Yuguo Li, Joel Tang, Jia Zhang, Peter C M van Zijl, Guanshu Liu
The development of new analytical methods to accurately quantify hydrogen peroxide is of great interest. In the current study, we developed a new magnetic resonance (MR) method for noninvasively quantifying hydrogen peroxide (H2O2) in aqueous solutions based on chemical exchange saturation transfer (CEST), an emerging MRI contrast mechanism. Our method can detect H2O2 by its specific CEST signal at ~6.2 ppm downfield from water resonance, with more than 1000 times signal amplification compared to the direct NMR detection...
June 19, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28620772/book-review-chemical-exchange-saturation-transfer-imaging-advances-and-applications-michael-t-mcmahon-assaf-a-gilad-jeff-w-m-bulte-and-peter-c-m-van-zijl-editors-pan-stanford-publishing-2017-isbn-9789814745703-pp-496
#3
Kevin Brindle
No abstract text is available yet for this article.
June 15, 2017: Molecular Imaging and Biology: MIB: the Official Publication of the Academy of Molecular Imaging
https://www.readbyqxmd.com/read/28590070/chemical-exchange-rotation-transfer-imaging-of-intermediate-exchanging-amines-at-2%C3%A2-ppm
#4
Zhongliang Zu, Elizabeth A Louie, Eugene C Lin, Xiaoyu Jiang, Mark D Does, John C Gore, Daniel F Gochberg
Chemical exchange saturation transfer (CEST) imaging of amine protons exchanging at intermediate rates and whose chemical shift is around 2 ppm may provide a means of mapping creatine. However, the quantification of this effect may be compromised by the influence of overlapping CEST signals from fast-exchanging amines and hydroxyls. We aimed to investigate the exchange rate filtering effect of a variation of CEST, named chemical exchange rotation transfer (CERT), as a means of isolating creatine contributions at around 2 ppm from other overlapping signals...
June 7, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28583638/a-phase-i-clinical-trial-of-the-knee-to-assess-the-correlation-of-gagcest-mri-delayed-gadolinium-enhanced-mri-of-cartilage-and-t2-mapping
#5
Wenbo Wei, Becky Lambach, Guang Jia, Christopher Kaeding, David Flanigan, Michael V Knopp
PURPOSE: Osteoarthritis (OA) is associated with the loss of glycosaminoglycan (GAG) during disease progression, which can be detected by glycosaminoglycan chemical exchange-dependent saturation transfer (gagCEST) MRI. Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is considered one of the standard methods for GAG quantification in vivo. This Phase I study assessed the correlation between gagCEST MRI and dGEMRIC in determining cartilage GAG concentration. Standard T2 mapping was used as a comparator with the two other methods...
May 2017: European Journal of Radiology
https://www.readbyqxmd.com/read/28566586/b1-power-optimization-for-chemical-exchange-saturation-transfer-imaging-a-phantom-study-using-egg-white-for-amide-proton-transfer-imaging-applications-in-the-human-brain
#6
Yuki Kanazawa, Yasutaka Fushimi, Naotaka Sakashita, Tomohisa Okada, Yoshiki Arakawa, Mitsue Miyazaki
The chemical exchange saturation transfer (CEST) effect on an egg white (EW) suspension was investigated for optimization of magnetization transfer (MT) power (B1,rms) and pH dependency with the addition of lactic acid. Applying a higher MT pulse, B1,rms, Z-spectrum shows higher asymmetry and the magnetisation transfer ratio (MTR)asym signal increases to around 1-3.5 ppm, indicating a higher CEST effect. Amide proton transfer (APT) at 3.5 ppm shows a signal elevation in MTRasym with the application of higher B1,rms power and high pH...
May 31, 2017: Magnetic Resonance in Medical Sciences: MRMS
https://www.readbyqxmd.com/read/28558795/non-caloric-sweetener-provides-magnetic-resonance-imaging-contrast-for-cancer-detection
#7
Puneet Bagga, Mohammad Haris, Kevin D'Aquilla, Neil E Wilson, Francesco M Marincola, Mitchell D Schnall, Hari Hariharan, Ravinder Reddy
BACKGROUND: Image contrast enhanced by exogenous contrast agents plays a crucial role in the early detection, characterization, and determination of the precise location of cancers. Here, we investigate the feasibility of using a non-nutritive sweetener, sucralose (commercial name, Splenda), as magnetic resonance imaging (MRI) contrast agent for cancer studies. METHODS: High-resolution nuclear-magnetic-resonance spectroscopy and MR studies on sucralose solution phantom were performed to detect the chemical exchange saturation transfer (CEST) property of sucralose hydroxyl protons with bulk water (sucCEST)...
May 30, 2017: Journal of Translational Medicine
https://www.readbyqxmd.com/read/28547862/mri-evaluation-of-regional-and-longitudinal-changes-in-z-spectra-of-injured-spinal-cord-of-monkeys
#8
Feng Wang, Zhongliang Zu, Ruiqi Wu, Tung-Lin Wu, John C Gore, Li Min Chen
PURPOSE: In principle, MR methods that exploit magnetization transfer (MT) may be used to quantify changes in the molecular composition of tissues after injury. The ability to track such changes in injured spinal cord may allow more precise assessment of the state of neural tissues. METHODS: Z-Spectra were obtained from the cervical spinal cord before and after a unilateral dorsal column lesion in monkeys at 9.4T. The amplitudes of chemical exchange saturation transfer (CEST) and nuclear Overhauser enhancement (NOE) effects from multiple proton pools, along with nonspecific semisolid MT effects from immobile macromolecules, were quantified using a five-peak Lorenzian fitting of each Z-spectrum...
May 25, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28544035/chemical-exchange-sensitive-mri-of-amide-amine-and-noe-at-9-4%C3%A2-t-versus-15-2%C3%A2-t
#9
Julius Juhyun Chung, Wonmin Choi, Tao Jin, Jung Hee Lee, Seong-Gi Kim
Chemical exchange (CE)-sensitive MRI benefits greatly from stronger magnetic fields; however, field effects on CE-sensitive imaging have not yet been studied well in vivo. We have compared CE-sensitive Z-spectra and maps obtained at the fields of 9.4 T and 15.2 T in phantoms and rats with off-resonance chemical-exchange-sensitive spin lock (CESL), which is similar to conventional chemical exchange saturation transfer. At higher fields, the background peak at water resonance has less spread and the exchange rate relative to chemical shift decreases, thus CESL intensity is dependent on B0 ...
May 22, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28526431/measurement-of-apt-using-a-combined-cert-arex-approach-with-varying-duty-cycles
#10
Zhongliang Zu, Hua Li, Junzhong Xu, Xiao-Yong Zhang, Moritz Zaiss, Ke Li, Mark D Does, John C Gore, Daniel F Gochberg
The goal is to develop an imaging method where contrast reflects amide-water magnetization exchange, with minimal signal contributions from other sources. Conventional chemical exchange saturation transfer (CEST) imaging of amides (often called amide proton transfer, or APT, and quantified by the metric MTRasym) is confounded by several factors unrelated to amides, such as aliphatic protons, water relaxation, and macromolecular magnetization transfer. In this work, we examined the effects of combining our previous chemical exchange rotation (CERT) approach with the non-linear AREX method while using different duty cycles (DC) for the label and reference scans...
May 17, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28501855/extracellular-ph-is-a-biomarker-enabling-detection-of-breast-cancer-and-liver-cancer-using-cest-mri
#11
Miaomiao Chen, Chaoying Chen, Zhiwei Shen, Xiaolei Zhang, Yanzi Chen, Fengfeng Lin, Xilun Ma, Caiyu Zhuang, Yifei Mao, Haochuan Gan, Peidong Chen, Xiaodan Zong, Renhua Wu
Extracellular pH (pHe) decrease is associated with tumor growth, invasion, metastasis, and chemoresistance, which can be detected by chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI). Here, we demonstrated that ioversol CEST MRI can be exploited to achieve pHe mapping of the liver cancer microenvironment. In in vitro studies, we firstly explored whether ioversol signal is pH-dependent, and calculated the function equation between the CEST effects of ioversol and pH values, in the range of 6...
April 25, 2017: Oncotarget
https://www.readbyqxmd.com/read/28497566/cest-mri-of-3-o-methyl-d-glucose-on-different-breast-cancer-models
#12
Michal Rivlin, Gil Navon
PURPOSE: To test the ability of chemical exchange saturation transfer (CEST) MRI of 3-O-methyl-D-glucose (3OMG) to detect tumors in several breast cancer models of murine and human origin, for different routes of administration of the agent and to compare the method with glucoCEST and with (18) FDG-PET on the same animals. METHODS: In vivo CEST MRI experiments were performed with a 7T Biospec animal MRI scanner on implanted orthotopic mammary tumors of mice before and after administration of 3OMG...
May 12, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28480619/rapid-and-simultaneous-measurement-of-phosphorus-metabolite-pool-size-ratio-and-reaction-kinetics-of-enzymes-in-vivo
#13
Sang-Young Kim, Wei Chen, Dost Ongur, Fei Du
PURPOSE: The metabolites phosphocreatine (PCr), adenosine triphosphate (ATP), and in-organic phosphate (Pi) are biochemically coupled. Their pool sizes, assessed by their magnetization ratios, have been extensively studied and reflect bioenergetics status in vivo. However, most such studies have ignored chemical exchange and T1 relaxation effects. In this work, we aimed to extend the T1nom method to simultaneously quantify the reaction rate constants as well as phosphorus metabolite pool size ratios under partially relaxed conditions...
May 8, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28480589/quantification-and-tracking-of-genetically-engineered-dendritic-cells-for-studying-immunotherapy
#14
Amnon Bar-Shir, Lina Alon, Michael J Korrer, Hong Seo Lim, Nirbhay N Yadav, Yoshinori Kato, Arvind P Pathak, Jeff W M Bulte, Assaf A Gilad
PURPOSE: Genetically encoded reporters can assist in visualizing biological processes in live organisms and have been proposed for longitudinal and noninvasive tracking of therapeutic cells in deep tissue. Cells can be labeled in situ or ex vivo and followed in live subjects over time. Nevertheless, a major challenge for reporter systems is to identify the cell population that actually expresses an active reporter. METHODS: We have used a nucleoside analog, pyrrolo-2'-deoxycytidine, as an imaging probe for the putative reporter gene, Drosophila melanogaster 2'-deoxynucleoside kinase...
May 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28474409/amide-proton-transfer-cest-of-the-cervical-spinal-cord-in-multiple-sclerosis-patients-at-3t
#15
Samantha By, Robert L Barry, Alex K Smith, Bailey D Lyttle, Bailey A Box, Francesca R Bagnato, Siddharama Pawate, Seth A Smith
PURPOSE: The ability to evaluate pathological changes in the spinal cord in multiple sclerosis (MS) is limited because T1 - and T2 -w MRI imaging are not sensitive to biochemical changes in vivo. Amide proton transfer (APT) chemical exchange saturation transfer (CEST) can indirectly detect amide protons associated with proteins and peptides, potentially providing more pathological specificity. Here, we implement APT CEST in the cervical spinal cord of healthy and MS cohorts at 3T. METHODS: APT CEST of the cervical spinal cord was obtained in a cohort of 10 controls and 10 MS patients using a novel respiratory correction methodology...
May 5, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28470934/lanthanide-complexes-in-molecular-magnetic-resonance-imaging-and-theranostics
#16
REVIEW
Sara Lacerda, Éva Tóth
Lanthanide complexes have attracted much attention in the biomedical field, and today various imaging applications make use of their versatile magnetic and luminescence properties. In this minireview, we give insight into the mechanistic aspects that allow modulation of the relaxation or chemical exchange saturation transfer (CEST) features, and thus the magnetic resonance imaging (MRI) efficiency of paramagnetic lanthanide chelates in order to create agents that are capable of providing an MRI response as a function of a specific biomarker...
June 21, 2017: ChemMedChem
https://www.readbyqxmd.com/read/28435103/magnetization-transfer-contrast-and-chemical-exchange-saturation-transfer-mri-features-and-analysis-of-the-field-dependent-saturation-spectrum
#17
Peter C M van Zijl, Wilfred W Lam, Jiadi Xu, Linda Knutsson, Greg J Stanisz
Magnetization Transfer Contrast (MTC) and Chemical Exchange Saturation Transfer (CEST) experiments measure the transfer of magnetization from molecular protons to the solvent water protons, an effect that becomes apparent as an MRI signal loss ("saturation"). This allows molecular information to be accessed with the enhanced sensitivity of MRI. In analogy to Magnetic Resonance Spectroscopy (MRS), these saturation data are presented as a function of the chemical shift of participating proton groups, e.g. OH, NH, NH2, which is called a Z-spectrum...
April 21, 2017: NeuroImage
https://www.readbyqxmd.com/read/28433532/exci-cest-exploiting-pharmaceutical-excipients-as-mri-cest-contrast-agents-for-tumor-imaging
#18
Dario Livio Longo, Fatima Zzahra Moustaghfir, Alexandre Zerbo, Lorena Consolino, Annasofia Anemone, Martina Bracesco, Silvio Aime
Chemical Exchange Saturation Transfer (CEST) approach is a novel tool within magnetic resonance imaging (MRI) that allows visualization of molecules possessing exchangeable protons with water. Many molecules, employed as excipients for the formulation of finished drug products, are endowed with hydroxyl, amine or amide protons, thus can be exploitable as MRI-CEST contrast agents. Their high safety profiles allow them to be injected at very high doses. Here we investigated the MRI-CEST properties of several excipients (ascorbic acid, sucrose, N-acetyl-d-glucosamine, meglumine and 2-pyrrolidone) and tested them as tumor-detecting agents in two different murine tumor models (breast and melanoma cancers)...
April 20, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28393130/oxidation-responsive-eu-ii-iii-based-multimodal-contrast-agent-for-magnetic-resonance-and-photoacoustic-imaging
#19
Lina A Basal, Yan Yan, Yimin Shen, E Mark Haacke, Mohammad Mehrmohammadi, Matthew J Allen
We report, for the first time, a multimodal, oxidation-responsive contrast agent for magnetic resonance imaging and photoacoustic imaging that uses the differences in the properties between Eu in the +2 and +3 oxidation states. The enhancement of contrast in T1-weighted magnetic resonance and photoacoustic imaging was observed in the +2 but not in the +3 oxidation state, and the complex is a known chemical exchange saturation transfer agent for magnetic resonance imaging in the +3 oxidation state.
March 31, 2017: ACS Omega
https://www.readbyqxmd.com/read/28384568/combination-of-a-crop-model-and-a-geochemical-model-as-a-new-approach-to-evaluate-the-sustainability-of-an-intensive-agriculture-system
#20
Gihan Mohammed, Fabienne Trolard, Marina Gillon, Anne-Laure Cognard-Plancq, André Chanzy, Guilhem Bourrié
By combining a crop model (STICS) and a geochemical model (PHREEQC), a new approach to assess the sustainability of agrosystems is proposed. It is based upon aqueous geochemistry and the stepwise modifications of soil solution during its transfer from the surface till aquifer. Meadows of Crau (SE France), irrigated since the 16th century, were field monitored (2012-2015) and modelled. Except for N, the mineral requirements of hay are largely covered by dissolved elements brought by irrigation water with only slight deficits in K and P, which are compensated by P-K fertilizers and the winter pasture by sheep...
October 1, 2017: Science of the Total Environment
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