keyword
MENU ▼
Read by QxMD icon Read
search

CEST

keyword
https://www.readbyqxmd.com/read/28435103/magnetization-transfer-contrast-and-chemical-exchange-saturation-transfer-mri-features-and-analysis-of-the-field-dependent-saturation-spectrum
#1
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 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28433532/exci-cest-exploiting-pharmaceutical-excipients-as-mri-cest-contrast-agents-for-tumor-imaging
#2
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 19, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28370884/detecting-in-vivo-urokinase-plasminogen-activator-activity-with-a-catalycest-mri-contrast-agent
#3
Sanhita Sinharay, Christine M Howison, Amanda F Baker, Mark D Pagel
Urokinase plasminogen activator (uPA) promotes tumor invasion and metastasis. The monitoring of uPA activity using molecular imaging may have prognostic value and be predictive for response to anti-cancer therapies. However, the detection of in vivo enzyme activity with molecular imaging remains a challenge. To address this problem, we designed a nonmetallic contrast agent, GR-4Am-SA, that can be detected with chemical exchange saturation transfer (CEST) MRI. This agent has a peptide that is cleaved by uPA, which causes a CEST signal at 5...
March 29, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28370655/detection-of-dt-diaphorase-enzyme-with-a-paracest-mri-contrast-agent
#4
Iman Daryaei, Kyle M Jones, Mark D Pagel
A responsive magnetic resonance (MRI) contrast agent has been developed that can detect the enzyme activity of DT-diaphorase. The agent produced different chemical exchange saturation transfer (CEST) MRI signals before and after incubation with the enzyme, NADH, and GSH at different pH values whereas it showed good stability in a reducing environment without enzyme.
March 30, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28370530/noninvasive-evaluation-of-renal-ph-homeostasis-after-ischemia-reperfusion-injury-by-cest-mri
#5
Dario Livio Longo, Juan Carlos Cutrin, Filippo Michelotti, Pietro Irrera, Silvio Aime
Acute kidney injury (AKI) in mice caused by sustained ischemia followed by reperfusion is associated with acute tubular necrosis and renal dysfunctional blood flow. Although the principal role of the kidney is the maintenance of acid-base balance, current imaging approaches are unable to assess this important parameter, and clinical biomarkers are not robust enough in evaluating the severity of kidney damage. Therefore, novel noninvasive imaging approaches are needed to assess the acid-base homeostasis in vivo...
March 29, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28358208/imidazole-appended-macrocyclic-complexes-of-fe-ii-co-ii-and-ni-ii-as-paracest-agents
#6
Patrick J Burns, Jordan M Cox, Janet R Morrow
The solution chemistry and solid state structures of the Co(II), Fe(II), and Ni(II) complexes of N,N'-bis(imidazole-2-ylmethyl)-4,10-diaza-15-crown-5 (HINO) are reported. The Co(II) and Ni(II) complexes of HINO are the first examples of paraCEST agents (paramagnetic chemical exchange saturation transfer) that feature exchangeable imidazole NH protons. The crystal structures of [Co(HINO)]CoCl4·H2O and [Fe(HINO)](CF3SO3)2 have the metal ions coordinated to four nitrogen and three oxygen donor atoms of the macrocyclic ligand in a distorted pentagonal bipyramidal geometry...
March 30, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28357518/longitudinal-relaxation-optimized-amide-1-h-cest-experiments-for-studying-slow-chemical-exchange-processes-in-fully-protonated-proteins
#7
Tairan Yuwen, Lewis E Kay
Chemical Exchange Saturation Transfer (CEST) experiments are increasingly used to study slow timescale exchange processes in biomolecules. Although (15)N- and (13)C-CEST have been the approaches of choice, the development of spin state selective (1)H-CEST pulse sequences that separate the effects of chemical and dipolar exchange [T. Yuwen, A. Sekhar and L. E. Kay, Angew Chem Int Ed Engl 2016 doi: 10.1002/anie.201610759 (Yuwen et al. 2017)] significantly increases the utility of (1)H-based experiments. Pulse schemes have been described previously for studies of highly deuterated proteins...
March 29, 2017: Journal of Biomolecular NMR
https://www.readbyqxmd.com/read/28321903/spin-lock-imaging-of-exogenous-exchange-based-contrast-agents-to-assess-tissue-ph
#8
Zhongliang Zu, Hua Li, Xiaoyu Jiang, John C Gore
PURPOSE: Some X-ray contrast agents contain exchangeable protons that give rise to exchange-based effects on MRI, including chemical exchange saturation transfer (CEST). However, CEST has poor specificity to explicit exchange parameters. Spin-lock sequences at high field are also sensitive to chemical exchange. Here, we evaluate whether spin-locking techniques can detect the contrast agent iohexol in vivo after intravenous administration, and their potential for measuring changes in tissue pH...
March 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28321227/co-expression-with-the-type-3-secretion-chaperone-cest-from-enterohemorrhagic-e-coli-increases-accumulation-of-recombinant-tir-in-plant-chloroplasts
#9
Jacqueline MacDonald, Sean Miletic, Typhanie Gaildry, Adam Chin-Fatt, Rima Menassa
Type 3 secretion systems (T3SSs) are utilized by pathogenic Escherichia coli to infect their hosts and many proteins from these systems are affected by chaperones specific to T3SS-containing bacteria. Toward developing a recombinant vaccine against enterohaemorrhagic E. coli (EHEC), we expressed recombinant T3SS and related proteins from predominant EHEC serotypes in Nicotiana chloroplasts. Nicotiana benthamiana were transiently transformed to express chloroplast-targeted Tir, NleA, and EspD from the EHEC serotype O157:H7; a fusion of EspA proteins from serotypes O157:H7 and O26:H11; and a fusion of epitopes of Tir (Tir-ep) from serotypes O157:H7, O26:H11, O45:H2, and O111:H8...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28317074/probing-conformational-dynamics-in-biomolecules-via-chemical-exchange-saturation-transfer-a-primer
#10
Pramodh Valluruapalli, Ashok Sekhar, Tairan Yuwen, Lewis E Kay
Although Chemical Exchange Saturation Transfer (CEST) type NMR experiments have been used to study chemical exchange processes in molecules since the early 1960s, there has been renewed interest in the past several years in using this approach to study biomolecular conformational dynamics. The methodology is particularly powerful for the study of sparsely populated, transiently formed conformers that are recalcitrant to investigation using traditional biophysical tools, and it is complementary to relaxation dispersion and magnetization transfer experiments that have traditionally been used to study chemical exchange processes...
March 19, 2017: Journal of Biomolecular NMR
https://www.readbyqxmd.com/read/28283707/evaluating-the-cartilage-adjacent-to-the-site-of-repair-surgery-with-glycosaminoglycan-specific-magnetic-resonance-imaging
#11
Ulrich Koller, Sebastian Apprich, Benjamin Schmitt, Reinhard Windhager, Siegfried Trattnig
PURPOSE: The glycosaminoglycan (GAG) chemical exchange saturation transfer (CEST) imaging method (gagCEST) makes it possible to assess and quantify the GAG concentration in human cartilage. This biochemical imaging technique facilitates detection of the loss of GAG in the course of osteoarthritis. The gagCEST technique was used to analyse the perilesional zone (PLZ) adjacent to repair tissue after cartilage repair surgery, to determine whether there are biochemical changes present in the sense of degeneration...
March 10, 2017: International Orthopaedics
https://www.readbyqxmd.com/read/28273886/quantitative-chemical-exchange-saturation-transfer-cest-mri-of-glioma-using-image-downsampling-expedited-adaptive-least-squares-ideal-fitting
#12
Iris Yuwen Zhou, Enfeng Wang, Jerry S Cheung, Xiaoan Zhang, Giulia Fulci, Phillip Zhe Sun
Chemical Exchange Saturation Transfer (CEST) MRI is sensitive to dilute metabolites with exchangeable protons, allowing tissue characterization in diseases such as acute stroke and tumor. CEST quantification using multi-pool Lorentzian fitting is challenging due to its strong dependence on image signal-to-noise ratio (SNR), initial values and boundaries. Herein we proposed an Image Downsampling Expedited Adaptive Least-squares (IDEAL) fitting algorithm that quantifies CEST images based on initial values from multi-pool Lorentzian fitting of iteratively less downsampled images until the original resolution...
December 2017: Scientific Reports
https://www.readbyqxmd.com/read/28272785/cest-imaging-of-fast-exchanging-amine-pools-with-corrections-for-competing-effects-at-9-4%C3%A2-t
#13
Xiao-Yong Zhang, Feng Wang, Hua Li, Junzhong Xu, Daniel F Gochberg, John C Gore, Zhongliang Zu
Chemical exchange saturation transfer (CEST) imaging of fast exchanging amine protons at 3 ppm offset from the water resonant frequency is of practical interest, but quantification of fast exchanging pools by CEST is challenging. To effectively saturate fast exchanging protons, high irradiation powers need to be applied, but these may cause significant direct water saturation as well as non-specific semi-solid magnetization transfer (MT) effects, and thus decrease the specificity of the measured signal. In addition, the CEST signal may depend on the water longitudinal relaxation time (T1w ), which likely varies between tissues and with pathology, further reducing specificity...
March 8, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28272761/accuracy-in-the-quantification-of-chemical-exchange-saturation-transfer-cest-and-relayed-nuclear-overhauser-enhancement-rnoe-saturation-transfer-effects
#14
Xiao-Yong Zhang, Feng Wang, Hua Li, Junzhong Xu, Daniel F Gochberg, John C Gore, Zhongliang Zu
Accurate quantification of chemical exchange saturation transfer (CEST) effects, including dipole-dipole mediated relayed nuclear Overhauser enhancement (rNOE) saturation transfer, is important for applications and studies of molecular concentration and transfer rate (and thereby pH or temperature). Although several quantification methods, such as Lorentzian difference (LD) analysis, multiple-pool Lorentzian fits, and the three-point method, have been extensively used in several preclinical and clinical applications, the accuracy of these methods has not been evaluated...
March 8, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28248966/a-magnesium-induced-triplex-pre-organizes-the-sam-ii-riboswitch
#15
Susmita Roy, Heiko Lammert, Ryan L Hayes, Bin Chen, Regan LeBlanc, T Kwaku Dayie, José N Onuchic, Karissa Y Sanbonmatsu
Our 13C- and 1H-chemical exchange saturation transfer (CEST) experiments previously revealed a dynamic exchange between partially closed and open conformations of the SAM-II riboswitch in the absence of ligand. Here, all-atom structure-based molecular simulations, with the electrostatic effects of Manning counter-ion condensation and explicit magnesium ions are employed to calculate the folding free energy landscape of the SAM-II riboswitch. We use this analysis to predict that magnesium ions remodel the landscape, shifting the equilibrium away from the extended, partially unfolded state towards a compact, pre-organized conformation that resembles the ligand-bound state...
March 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28244138/b1-inhomogeneity-mitigation-in-cest-using-parallel-transmission
#16
Desmond H Y Tse, Nuno Andre da Silva, Benedikt A Poser, N Jon Shah
PURPOSE: In order to benefit from the increased spectral bandwidth at ultrahigh field (UHF), the use of parallel transmission (pTx) to mitigate flip-angle inhomogeneity in chemical exchange saturation transfer (CEST) imaging is investigated. THEORY AND METHODS: A pTx basis pulse is homogenised by magnitude least-squares (MLS) optimization and expanded to form a frequency-selective saturation pulse for CEST. The pTx saturation pulse was simulated with a three-pool Bloch-McConnell equation to evaluate the impact of pTx on CEST contrast...
February 28, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28220538/on-bead-combinatorial-synthesis-and-imaging-of-europium-iii-based-paracest-agents-aids-in-identification-of-chemical-features-that-enhance-cest-sensitivity
#17
Jaspal Singh, Vineeta Rustagi, Shanrong Zhang, A Dean Sherry, D Gomika Udugamasooriya
The rate of water exchange between the inner sphere of a paramagnetic ion and bulk water is an important parameter in determining the magnitude of the chemical exchange saturation transfer signal from paramagnetic CEST agents (paraCEST). This is governed by various geometric, steric and ligand field factors created by macrocyclic ligands surrounding the paramagnetic metal ion. Our previous on-bead combinatorial studies of di-peptoid-europium(III)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-tetraamide complexes revealed that negatively charged groups in the immediate vicinity of the metal center strongly enhances the CEST signal...
February 21, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28209897/host-cell-attachment-elicits-posttranscriptional-regulation-in-infecting-enteropathogenic-bacteria
#18
Naama Katsowich, Netanel Elbaz, Ritesh Ranjan Pal, Erez Mills, Simi Kobi, Tamar Kahan, Ilan Rosenshine
The mechanisms by which pathogens sense the host and respond by remodeling gene expression are poorly understood. Enteropathogenic Escherichia coli (EPEC), the cause of severe intestinal infection, employs a type III secretion system (T3SS) to inject effector proteins into intestinal epithelial cells. These effectors subvert host cell processes to promote bacterial colonization. We show that the T3SS also functions to sense the host cell and to trigger in response posttranscriptional remodeling of gene expression in the bacteria...
February 17, 2017: Science
https://www.readbyqxmd.com/read/28192930/mitochondria-targeted-and-intracellular-biothiol-triggered-hyperpolarized-129-xe-magnetofluorescent-biosensor
#19
Qingbin Zeng, Qianni Guo, Yaping Yuan, Yuqi Yang, Bin Zhang, Lili Ren, Xiaoxiao Zhang, Qing Luo, Maili Liu, Louis-S Bouchard, Xin Zhou
Biothiols such as gluthathione (GSH), cysteine (Cys), homocysteine (Hcy), and thioredoxin (Trx) play vital roles in cellular metabolism. Various diseases are associated with abnormal cellular biothiol levels. Thus, the intracellular detection of biothiol levels could be a useful diagnostic tool. A number of methods have been developed to detect intracellular thiols, but sensitivity and specificity problems have limited their applications. To address these limitations, we have designed a new biosensor based on hyperpolarized xenon magnetic resonance detection, which can be used to detect biothiol levels noninvasively...
February 9, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28179167/mri-and-mrs-of-the-human-brain-at-magnetic-fields-of-14t-to-20t-technical-feasibility-safety-and-neuroscience-horizons
#20
Thomas F Budinger, Mark D Bird
The three goals of this paper are: 1) to evaluate the improvements in technology for increasing magnetic flux density (magnetic field) to 14T in the next few years and eventually to 20T; 2) to highlight neuroscience opportunities enabled by these advances; and, 3) to evaluate the physiological and biophysical effects associated with MRI at very high performance levels. Substantial recent advances in magnet technology including superconductor developments enable neuroscience goals that are not obtainable at contemporary magnetic fields...
February 5, 2017: NeuroImage
keyword
keyword
28346
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"