keyword
MENU ▼
Read by QxMD icon Read
search

Chemical exchange saturation transfer

keyword
https://www.readbyqxmd.com/read/29149466/microsecond-timescale-protein-dynamics-a-combined-solid-state-nmr-approach
#1
Petra Rovó, Rasmus Linser
Conformational exchange in proteins is a major determinant in protein functionality. In particular, the μs-ms timescale is associated with enzymatic activity and interactions between biological molecules. We show here that a comprehensive data set of R1ρ relaxation dispersion profiles employing multiple effective fields and tilt angles can be easily obtained in perdeuterated, partly back-exchanged proteins at fast magic-angle spinning and further complemented with chemical-exchange saturation transfer NMR experiments...
November 17, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
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
#2
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
#3
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/29111410/the-z-spectrum-from-human-blood-at-7t
#4
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/29067395/toward-inert-paramagnetic-ni-ii-based-chemical-exchange-saturation-transfer-mri-agents
#5
Laura Caneda-Martínez, Laura Valencia, Isabel Fernández-Pérez, Martín Regueiro-Figueroa, Goran Angelovski, Isabel Brandariz, David Esteban-Gómez, Carlos Platas-Iglesias
The Ni(2+) complexes with hexadentate ligands containing two 6-methylpicolinamide groups linked by ethane-1,2-diamine (dedpam) or cyclohexane-1,2-diamine (chxdedpam) spacers were investigated as potential contrast agents in magnetic resonance imaging (MRI). The properties of the complexes were compared to that of the analogues containing 6-methylpicolinate units (dedpa(2-) and chxdedpa(2-)). The X-ray structure of the [Ni(dedpam)](2+) complex reveals a six-coordinated metal ion with a distorted octahedral environment...
November 7, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29059929/assessment-of-chemoradiotherapy-response-in-glioma-with-magnetic-resonance-amide-proton-transfer-imaging-in-a-rodent-model
#6
Jing Zhao, Yinsheng Chen, Yiying Zhao, Shasha Yang, Zhongping Chen, Yin Wu
Magnetic resonance amide proton transfer (APT) imaging has proved its potential for detecting tumors and evaluating treatment response by depicting chemical exchange saturation transfer effect between the endogenous protein/peptide amide proton and bulk water. However, conventional asymmetry analysis for APT effect measurement is susceptible to concomitant contributions, particular semisolid magnetic transfer (MT) and nuclear overhauser effect. In this study, dominant saturation transfer (ST) effects, including direct water saturation and MT, were estimated from a sum of two Lorentzian functions...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
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
#7
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
https://www.readbyqxmd.com/read/29028326/ratiometric-ph-imaging-with-a-co-ii-2-mri-probe-via-cest-effects-of-opposing-ph-dependences
#8
Agnes E Thorarinsdottir, Kang Du, James H P Collins, T David Harris
We report a Co2-based magnetic resonance (MR) probe that enables the ratiometric quantitation and imaging of pH through chemical exchange saturation transfer (CEST). This approach is illustrated in a series of air- and water-stable Co(II)2 complexes featuring CEST-active tetra(carboxamide) and/or hydroxyl-substituted bisphosphonate ligands. For the complex bearing both ligands, variable-pH CEST and NMR analyses reveal highly shifted carboxamide and hydroxyl peaks with intensities that increase and decrease with increasing pH, respectively...
October 30, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29024066/a-comparison-of-exogenous-and-endogenous-cest-mri-methods-for-evaluating-in-vivo-ph
#9
Leila R Lindeman, Edward A Randtke, Rachel A High, Kyle M Jones, Christine M Howison, Mark D Pagel
PURPOSE: Extracellular pH (pHe) is an important biomarker for cancer cell metabolism. Acido-chemical exchange saturation transfer (CEST) MRI uses the contrast agent iopamidol to create spatial maps of pHe. Measurements of amide proton transfer exchange rates (kex ) from endogenous CEST MRI were compared to pHe measurements by exogenous acido-CEST MRI to determine whether endogenous kex could be used as a proxy for pHe measurements. METHODS: Spatial maps of pHe and kex were obtained using exogenous acidoCEST MRI and an endogenous CEST MRI analyzed with the omega plot method, respectively, to evaluate mouse kidney, a flank tumor model, and a spontaneous lung tumor model...
October 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28989612/inside-information-on-xenon-adsorption-in-porous-organic-cages-by-nmr
#10
Sanna Komulainen, Juho Roukala, Vladimir V Zhivonitko, Muhammad Asadullah Javed, Linjiang Chen, Daniel Holden, Tom Hasell, Andrew Cooper, Perttu Lantto, Ville-Veikko Telkki
A solid porous molecular crystal formed from an organic cage, CC3, has unprecedented performance for the separation of rare gases. Here, xenon was used as an internal reporter providing extraordinarily versatile information about the gas adsorption phenomena in the cage and window cavities of the material. (129)Xe NMR measurements combined with state-of-the-art quantum chemical calculations allowed the determination of the occupancies of the cavities, binding constants, thermodynamic parameters as well as the exchange rates of Xe between the cavities...
August 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28979760/ratiometric-quantitation-of-redox-status-with-a-molecular-fe2-magnetic-resonance-probe
#11
Kang Du, Emily A Waters, T David Harris
We demonstrate the ability of a molecular Fe2 complex to enable magnetic resonance (MR)-based ratiometric quantitation of redox status, namely through redox-dependent paramagnetic chemical exchange saturation transfer (PARACEST). Metalation of a tetra(carboxamide) ligand with Fe(II) and/or Fe(III) in the presence of etidronate ion affords analogous FeII2, Fe(II)Fe(III), and FeIII2 complexes. Both FeII2 and Fe(II)Fe(III) complexes give highly-shifted, sharp, and non-overlapping NMR spectra, with multiple resonances for each complex corresponding to exchangeable carboxamide protons...
June 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28978895/magnetic-resonance-imaging-of-neurotransmitter-related-molecules
#12
Hironaka Igarashi, Satoshi Ueki, Ken Ohno, Masaki Ohkubo, Yuji Suzuki
Molecular imaging implies the method capable of pictorially displaying distribution of target molecules and their relative concentration in space. In clinical medicine, where non-invasiveness is mandatory, diagnostic molecular imaging has been considered virtually identical to positron emission tomography (PET). However, there is another powerful, apparently underutilized molecular imaging, namely, proton magnetic resonance spectroscopic imaging ((1)H-MRSI). The technique can detect target molecules endogenous in brain in virtue of their own specific resonance frequencies (chemical shift) and can create quantitative images of each molecule...
2017: Journal of Nippon Medical School, Nippon Ika Daigaku Zasshi
https://www.readbyqxmd.com/read/28961344/investigation-of-the-contribution-of-total-creatine-to-the-cest-z-spectrum-of-brain-using-a-knockout-mouse-model
#13
Lin Chen, Haifeng Zeng, Xiang Xu, Nirbhay N Yadav, Shuhui Cai, Nicolaas A Puts, Peter B Barker, Tong Li, Robert G Weiss, Peter C M van Zijl, Jiadi Xu
The current study aims to assign and estimate the total creatine (tCr) signal contribution to the Z-spectrum in mouse brain at 11.7 T. Creatine (Cr), phosphocreatine (PCr) and protein phantoms were used to confirm the presence of a guanidinium resonance at this field strength. Wild-type (WT) and knockout mice with guanidinoacetate N-methyltransferase deficiency (GAMT-/-), which have low Cr and PCr concentrations in the brain, were used to assign the tCr contribution to the Z-spectrum. To estimate the total guanidinium concentrations, two pools for the Z-spectrum around 2 ppm were assumed: (i) a Lorentzian function representing the guanidinium chemical exchange saturation transfer (CEST) at 1...
December 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28915341/-31-p-magnetic-resonance-fingerprinting-for-rapid-quantification-of-creatine-kinase-reaction-rate-in-vivo
#14
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...
December 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
#15
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
#16
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
#17
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
#18
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/fluorine-pseudocontact-shifts-used-for-characterizing-the-protein-ligand-interaction-mode-in-the-limit-of-nmr-intermediate-exchange
#19
Jia Gao, E Liang, Rongsheng Ma, Fudong Li, Yixiang 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 (19) F 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 (19) F PCSs were retrieved from (19) F chemical exchange saturation transfer (CEST) in the presence of the lanthanide-labeled protein, which was termed the (19) F 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
#20
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
keyword
keyword
89902
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"