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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
#1
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/28862349/z-spectrum-appearance-and-interpretation-in-the-presence-of-fat-influence-of-acquisition-parameters
#2
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/28846825/use-of-fluorine-pseudocontact-shifts-to-characterize-the-protein-ligand-interaction-mode-in-the-limit-of-nmr-intermediate-exchange
#3
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/28792646/clinical-applications-of-chemical-exchange-saturation-transfer-cest-mri
#4
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-1-h%C3%A2-nmr-shift
#5
Giuseppe Ferrauto, Enza Di Gregorio, Marta Ruzza, Valeria Catanzaro, Sergio Padovan, Silvio Aime
Mobile proton-containing solutes can be detected by MRI by the chemical exchange saturation transfer (CEST) method. CEST sensitivity is dramatically enhanced by using, as exchanging protons, the water molecules confined inside liposomes, shifted by a paramagnetic shift reagent. The chemical shift of the intraliposomal water resonance (δ(IL) ) is affected by the overall shape of the supramolecular system. δ(IL) of a spherical LipoCEST acts as a sensitive reporter of the distribution of streptavidin proteins anchored at the liposome surface by biotinylated phospholipids...
July 26, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28741638/-19-f-cest-imaging-probes-for-metal-ion-detection
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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/28707688/probing-the-excited-state-chemical-shifts-and-exchange-parameters-by-nitrogen-decoupled-amide-proton-chemical-exchange-saturation-transfer-hn-dec-cest
#12
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
#13
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
https://www.readbyqxmd.com/read/28686796/quesp-and-quest-revisited-fast-and-accurate-quantitative-cest-experiments
#14
Moritz Zaiss, Goran Angelovski, Eleni Demetriou, Michael T McMahon, Xavier Golay, Klaus Scheffler
PURPOSE: Chemical exchange saturation transfer (CEST) NMR or MRI experiments allow detection of low concentrated molecules with enhanced sensitivity via their proton exchange with the abundant water pool. Be it endogenous metabolites or exogenous contrast agents, an exact quantification of the actual exchange rate is required to design optimal pulse sequences and/or specific sensitive agents. METHODS: Refined analytical expressions allow deeper insight and improvement of accuracy for common quantification techniques...
July 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28653349/assignment-of-the-molecular-origins-of-cest-signals-at-2%C3%A2-ppm-in-rat-brain
#15
Xiao-Yong Zhang, Jingping Xie, Feng Wang, Eugene C Lin, Junzhong Xu, Daniel F Gochberg, John C Gore, Zhongliang Zu
PURPOSE: Chemical exchange saturation transfer effects at 2 ppm (CEST@2ppm) in brain have previously been interpreted as originating from creatine. However, protein guanidino amine protons may also contribute to CEST@2ppm. This study aims to investigate the molecular origins and specificity of CEST@2ppm in brain. METHODS: Two experiments were performed: (i) samples containing egg white albumin and creatine were dialyzed using a semipermeable membrane to demonstrate that proteins and creatine can be separated by this method; and (ii) tissue homogenates of rat brain with and without dialysis to remove creatine were studied to measure the relative contributions of proteins and creatine to CEST@2ppm...
September 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28647789/probing-slow-timescale-dynamics-in-proteins-using-methyl-1-h-cest
#16
Tairan Yuwen, Rui Huang, Lewis E Kay
Although (15)N- and (13)C-based chemical exchange saturation transfer (CEST) experiments have assumed an important role in studies of biomolecular conformational exchange, (1)H CEST experiments are only beginning to emerge. We present a methyl-TROSY (1)H CEST experiment that eliminates deleterious (1)H-(1)H NOE dips so that CEST profiles can be analyzed robustly to extract methyl proton chemical shifts of rare protein conformers. The utility of the experiment, along with a version that is optimized for (13)CHD2 labeled proteins, is established through studies of exchanging protein systems...
July 2017: Journal of Biomolecular NMR
https://www.readbyqxmd.com/read/28644017/spectrally-undiscerned-isomers-might-lead-to-erroneous-determination-of-water-exchange-rates-of-paracest-eu-iii-agents
#17
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...
July 17, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28636798/a-ccpe-based-xenon-biosensor-for-magnetic-resonance-imaging-of-claudin-expressing-cells
#18
Anna Piontek, Christopher Witte, Honor May Rose, Miriam Eichner, Jonas Protze, Gerd Krause, Jörg Piontek, Leif Schröder
The majority of malignant tumors originate from epithelial cells, and many of them are characterized by an overexpression of claudins (Cldns) and their mislocalization out of tight junctions. We utilized the C-terminal claudin-binding domain of Clostridium perfringens enterotoxin (cCPE), with its high affinity to specific members of the claudin family, as the targeting unit for a claudin-sensitive cancer biosensor. To overcome the poor sensitivity of conventional relaxivity-based magnetic resonance imaging (MRI) contrast agents, we utilized the superior sensitivity of xenon Hyper-CEST biosensors...
June 2017: Annals of the New York Academy of Sciences
https://www.readbyqxmd.com/read/28627877/detection-and-quantification-of-hydrogen-peroxide-in-aqueous-solutions-using-chemical-exchange-saturation-transfer
#19
David Ryoo, Xiang Xu, Yuguo Li, Joel A 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...
July 5, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28602944/enhancing-sensitivity-of-ph-weighted-mri-with-combination-of-amide-and-guanidyl-cest
#20
Tao Jin, Ping Wang, T Kevin Hitchens, Seong-Gi Kim
Amide-proton-transfer weighted (APTw) MRI has emerged as a non-invasive pH-weighted imaging technique for studies of several diseases such as ischemic stroke. However, its pH-sensitivity is relatively low, limiting its capability to detect small pH changes. In this work, computer simulations, protamine phantom experiments, and in vivo gas challenge and experimental stroke in rats showed that, with judicious selection of the saturation pulse power, the amide-CEST at 3.6ppm and guanidyl-CEST signals at 2.0ppm changed in opposite directions with decreased pH...
August 15, 2017: NeuroImage
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