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https://www.readbyqxmd.com/read/28547862/mri-evaluation-of-regional-and-longitudinal-changes-in-z-spectra-of-injured-spinal-cord-of-monkeys
#1
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/28526431/measurement-of-apt-using-a-combined-cert-arex-approach-with-varying-duty-cycles
#2
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/28507560/corrigendum-co-expression-with-the-type-3-secretion-chaperone-cest-from-enterohemorrhagic-e-coli-increases-accumulation-of-recombinant-tir-in-plant-chloroplasts
#3
Jacqueline MacDonald, Sean Miletic, Typhanie Gaildry, Adam Chin-Fatt, Rima Menassa
[This corrects the article on p. 283 in vol. 8, PMID: 28321227.].
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28501855/extracellular-ph-is-a-biomarker-enabling-detection-of-breast-cancer-and-liver-cancer-using-cest-mri
#4
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
#5
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/28474409/amide-proton-transfer-cest-of-the-cervical-spinal-cord-in-multiple-sclerosis-patients-at-3t
#6
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
#7
Eva Toth, Sara Lacerda
Lanthanide complexes have attracted continuous attention in the biomedical field and today various imaging applications make use of their versatile magnetic and luminescence properties. In this minireview, we give insights into the mechanistic aspects that allow modulating the relaxation or chemical exchange saturation transfer (CEST) features, thus the 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...
May 4, 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
#8
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
#9
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/28370884/detecting-in-vivo-urokinase-plasminogen-activator-activity-with-a-catalycest-mri-contrast-agent
#10
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
#11
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.
May 11, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28370530/noninvasive-evaluation-of-renal-ph-homeostasis-after-ischemia-reperfusion-injury-by-cest-mri
#12
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
#13
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
#14
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
#15
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
#16
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
#17
Pramodh Vallurupalli, 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
#18
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
#19
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
#20
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
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