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1.

001-es BibID:BIBFORM002995
Első szerző:Ali, M. Meser
Cím:Albumin-binding PARACEST agents / M. Meser Ali, Mark Woods, Eul Hyun Suh, Zoltan Kovacs, Gyula Tircsó, Piyu Zhao, Vikram D. Kodibagkar, A. Dean Sherry
Dátum:2007
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal Of Biological Inorganic Chemistry. - 12 : 6 (2007), p. 855-865. -
További szerzők:Woods, Mark Suh, Eul Hyun Kovács Zoltán Tircsó Gyula (1977-) (vegyész, kémia tanár) Zhao, Piyu Kodibagkar, Vikram D. Sherry, A. Dean
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2.

001-es BibID:BIBFORM047919
Első szerző:Mani, Tomoyasu
Cím:The stereochemistry of amide side chains containing carboxyl groups influences water exchange rates in EuDOTA-tetraamide complexes / Tomoyasu Mani, Ana Christina L. Opina, Piyu Zhao, Osasere M. Evbuomwan, Nate Milburn, Gyula Tircso, Cemile Kumas, A. Dean Sherry
Dátum:2014
ISSN:0949-8257
Megjegyzések:Many Eu(III) complexes formed with DOTAtetraamide ligands (where DOTA is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) have sufficiently slow water exchange kinetics to meet the slow-to-intermediate condition required to serve as chemical exchange saturation transfer (CEST) contrast agents for MRI. This class of MRI contrast agents offers an attractive platform for creating biological sensors because water exchange is exquisitelysensitive to subtle ligand stereochemistry and electroniceffects. Introduction of carboxyl groups or carboxyl ethyl ester groups on the amide substituents has been shown to slow water exchange in these complexes, but less is known about the orientation or position of these side-chain groups relativeto the inner-sphere Eu(III)-bound water molecule. In thisstudy, a series of Eu(III) complexes having one or more carboxylgroups or carboxyl esters at the d-position of the pendantamide side chains were prepared. Initial attempts toprepare optically pure EuDOTA-[(S)-Asp]4 resulted in achemically pure ligand consisting of a mixture of stereochemical isomers. This was traced to racemization of (S)-aspartate diethyl ester during the synthetic procedure. Nevertheless, NMR studies of the Eu(III) complexes of this mixture revealed that each isomer had a different water exchange rate, differing by a factor of 2 or more. A second controlled synthesis and CEST study of EuDOTA-[(S)-Asp]4 and cis-EuDOTA-[(S)-Asp]2[(R)-Asp]2 confirmed that the water exchange rates in these diastereomeric complexes are controlled by the axial versus equatorial orientation of the carboxyl groups on the amide side chains. These observations provide new insights toward the development of even more slowly water exchanging systems which will be necessary for practical in vivo applications.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Lanthanide complexes
Macrocyclic conformations
MRI contrast agents
Water exchange
Megjelenés:Journal Of Biological Inorganic Chemistry. - 19 (2014), p. 161-171. -
További szerzők:Opina, Ana Christina L. Zhao, Piyu Evbuomwan, Osasere M. Milburn, Nate Tircsó Gyula (1977-) (vegyész, kémia tanár) Kumas, Cemile Sherry, A. Dean
Pályázati támogatás:K-84291
OTKA
TÁMOP-4.2.2.A-11/1/KONV-2012-0043
TÁMOP
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3.

001-es BibID:BIBFORM010526
Első szerző:Mani, Tomoyasu
Cím:Modulation of water exchange in Eu(III) DOTA-tetraamide complexes : considerations for in vivo imaging of PARACEST agents / Tomoyasu Mani, Gyula Tircsó, Osamu Togao, Piyu Zhao, Todd C. Soesbe, Masaya Takahashi, A. Dean Sherry
Dátum:2009
ISSN:1555-4309
Megjegyzések:Modulation of water exchange in lanthanide(III)-DOTA type complexes has drawn considerable attention over the past two decades, particularly because of their application as contrast agents for magnetic resonance imaging. LnDOTA-tetraamide complexes display unusually slow water exchange kinetics and this chemical property offers an opportunity to use these complexes as a new type of contrast agent based upon the chemical exchange saturation transfer (CEST) mechanism. Six new DOTA-tetraamide ligands having side-chain amide arms with varying hydrophobicity and polarity were prepared and the water exchange characteristic of complexes formed with europium(III) complexes were investigated. The results show that introduction of steric bulk into the amide side-chain arms of the europium(III) complexes not only favors formation of the mono-capped twisted square antiprism coordination isomers, the isomer that is generally less favourable for CEST, but also accelerates water exchange in the mono-capped square antiprism isomers. However, converting single methyl groups on these bulky arms to carboxyl or carboxyl ethyl esters results in a rather dramatic decrease in water exchange rates, about 50-fold. Thus, steric bulk, polarity and hydrophobicity of the amide side-chains each contribute to organization of water molecules in the second hydration sphere of the europium(III) ion and this in turn controls water exchange in these complexes. Copyright (C) 2009 John Wiley & Sons, Ltd.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Contrast Media & Molecular Imaging. - 4 : 4 (2009), p. 183-191. -
További szerzők:Tircsó Gyula (1977-) (vegyész, kémia tanár) Togao, Osamu Zhao, Piyu Soesbe, Todd C. Takahashi, Masaya Sherry, A. Dean
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4.

001-es BibID:BIBFORM010527
Első szerző:Mani, Tomoyasu
Cím:Effect of the Regiochemistry of Butyl Amide Substituents on the Solution-State Structures of Lanthanide(III) DOTA-Tetraamide Complexes / Tomoyasu Mani, Gyula Tircsó, Piyu Zhao, A. Dean Sherry, Mark Woods
Dátum:2009
ISSN:0020-1669
Megjegyzések:The coordination geometry adopted by the lanthanide complexes of DOTA-tetraamides is a critical factor in determining their water exchange kinetics. Controlling the water exchange kinetics of DOTA-tetraamide complexes, and by extension their coordination geometry, is of particular interest because of the potential application of this class of complex as PARACEST MRI contrast agents. To facilitate the maximum CEST effect at the lowest pre-saturation powers much slower exchange kinetics are required than are commonly observed with these types of chelates. Complexes that adopt the more slowly exchanging square antiprismatic coordination geometry are therefore preferred; however, the factors that govern which coordination geometry is preferred remain unclear. A series of DOTA-tetraamide complexes with butyl amide substituents in different regioisomeric configurations provides some insight into these factors. The population of each coordination geometry was found to vary substantially depending, upon the regiochemistry of the butyl amide substituent. It was observed that the twisted square antiprism coordiniition geometry, usually favored in complexes with the larger lanthanide ions only, is also increasingly favored for certain DOTA-tetraamide complexes with the smaller lanthanides. This is in marked contrast to simple DOTA-tetraamide complexes such as DOTAM. The effect was more prevalent in complexes formed with more bulky and more electron donating amide butyl substituents. It is also associated with loss of an inner-sphere water molecule from the complexes of later lanthanides that adopt the twisted square antiprismatic geometry. The complexes with sec-butyl substituents are inherently more complicated because of the introduction of a stereochemical center into each pendant arm. Unlike chiral complexes with larger amide substituents there is no "locking" effect of the orientation of the pendant arms in these complexes and up to four diastereoisomeric coordination isomers can be observed.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Inorganic Chemistry. - 48 : 21 (2009), p. 10338-10345. -
További szerzők:Tircsó Gyula (1977-) (vegyész, kémia tanár) Zhao, Piyu Sherry, A. Dean Woods, Mark
Internet cím:DOI
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5.

001-es BibID:BIBFORM003045
Első szerző:Vipond, Jeff
Cím:A bridge to coordination isomer selection in lanthanide(III) DOTA-tetraamide complexes / Jeff Vipond, Mark Woods, Piyu Zhao, Gyula Tircsó, Jimin Ren, Simon G. Bott, Doug Ogrin, Garry E. Kiefer, Zoltan Kovacs, A. Dean Sherry
Dátum:2007
ISSN:0020-1669
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Inorganic Chemistry. - 46 : 7 (2007), p. 2584-2595. -
További szerzők:Woods, Mark Zhao, Piyu Tircsó Gyula (1977-) (vegyész, kémia tanár) Ren, Jimin Bott, Simon G. Ogrin, Doug Kiefer, Garry E. Kovács Zoltán Sherry, A. Dean
Internet cím:elektronikus változat
elektronikus változat
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6.

001-es BibID:BIBFORM067446
Első szerző:Woods, Mark
Cím:Synthesis, relaxometric and photophysical properties of a new pH-responsive MRI contrast agent : The effect of other ligating groups on dissociation of a p-nitrophenolic pendant arm / Mark Woods, Garry E. Kiefer, Simon Bott, Aminta Castillo-Muzquiz, Carrie Eshelbrenner, Lydie Michaudet, Kenneth McMillan, Siva D. K. Mudigunda, Doug Ogrin, Gyula Tircsó, Shanrong Zhang, Piyu Zhao, A. Dean Sherry
Dátum:2004
ISSN:0002-7863
Megjegyzések:Two gadolinium(III) chelates, GdNP-DO3A (1-methlyene-(p-NitroPhenol)-1,4,7,10-tetraazacycloDOdecane-4,7,10-triAcetate) and GdNP-DO3AM (1-methlyene(p-NitroPhenol)-1,4,7,10-tetraazacycloDOdecane-4,7,10-triacetAMide), containing a single nitrophenolic pendant arm plus either three acetate or three amide pendant arms were synthesized and characterized. The properties of the gadolinium, terbium, and dysprosium complexes of these ligands were examined as a function of pH. The extent and mechanism of the changes in water relaxivity with pH of each gadolinium complex was found to differ substantially for the two complexes. The water relaxivity of Gd(NP-DO3A) increases from 4.1 mM-1 s-1 at pH 9 to 7.0 mM-1 s-1 at pH 5 as a result of acid-catalyzed dissociation of the nitrophenol from the lanthanide. The nitrophenol group in Gd(NP-DO3AM) does not dissociate from the metal center even at pH 5; therefore, the very modest increase in relaxivity in this complex must be ascribed to an increase in prototropic exchange rate of the bound water and/or phenolic protons.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
pH-Responsive MRI Contrast Agent
gadolinium
Synthesis
Relaxometric
Photophysical Properties
Megjelenés:Journal of the American Chemical Society 126 : 30 (2004), p. 9248-9256. -
További szerzők:Kiefer, Garry E. Bott, Simon G. Castillo-Muzquiz, Aminta Eshelbrenner, Carrie Michaudet, Lydie McMillan, Kenneth Mudigunda, Siva D. K. Ogrin, Doug Tircsó Gyula (1977-) (vegyész, kémia tanár) Zhang, Shanrong Zhao, Piyu Sherry, A. Dean
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7.

001-es BibID:BIBFORM018830
Első szerző:Woods, Mark
Cím:Investigations into whole water, prototropic and amide proton exchange in lanthanide(iii) DOTA-tetraamide chelates / Mark Woods, Azhar Pasha, Piyu Zhao, Gyula Tircso, Somdatta Chowdhury, Garry Kiefer, Donald E. Woessner, A. Dean Sherry
Dátum:2011
ISSN:1477-9226
Megjegyzések:Lanthanide(III) chelates of DOTA-tetraamide ligands have been an area of particular interest since the discovery that water exchange kinetics are dramatically affected by the switch from acetate to amide side-chain donors. More recently these chelates have attracted interest as potential PARACEST agents for use in MRI. In this paper we report the results of studies using chemical exchange saturation transfer (CEST) and some more recently reported chelates to re-examine the exchange processes in this class of chelate. We find that the conclusions of Parker and Aime are, for the most part, solid; water exchange is slow and a substantial amount of prototropic exchange occurs in aqueous solution. The extent of prototropic exchange increases as the pH increases above 8, leading to higher relaxivities at high pH. However, amide protons are found to contribute only a small amount to the relaxivity at high pH.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Dalton Transactions. - 40 : 25 (2011), p. 6759-6764. -
További szerzők:Pasha, Azhar Zhao, Piyu Tircsó Gyula (1977-) (vegyész, kémia tanár) Chowdhury, Somdatta Kiefer, Garry E. Woessner, Donald E. Sherry, A. Dean
Internet cím:DOI
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8.

001-es BibID:BIBFORM073137
Első szerző:Zhang, Lei
Cím:Lanthanide-Based T2ex and CEST Complexes Provide Insights into the Design of pH Sensitive MRI Agents / Lei Zhang, André F. Martins, Piyu Zhao, Yunkou Wu, Gyula Tircsó, A. Dean Sherry
Dátum:2017
ISSN:1433-7851 1521-3773
Megjegyzések:The CESTand T1/T2 relaxation properties of a seriesof Eu3+ and Dy3+ DOTA-tetraamide complexes with fourappended primary amine groups are measured as a function ofpH. The CEST signals in the Eu3+ complexes show a strongCEST signal after the pH was reduced from 8 to 5. Theopposite trend was observed for the Dy3+ complexes where ther2ex of bulk water protons increased dramatically from ca.1.5 mm@1 s@1 to 13 mm@1 s@1 between pH5 and 9 while r1remained unchanged. A fit of the CEST data (Eu3+ complexes)to Bloch theory and the T2ex data (Dy3+ complexes) to Swift?Connick theory provided the proton-exchange rates as a functionof pH. These data showed that the four amine groupscontribute significantly to proton-catalyzed exchange of theLn3+-bound water protons even though their pKaQs are muchhigher than the observed CEST or T2ex effects. This demonstratedthe utility of using appended acidic/basic groups tocatalyze prototropic exchange for imaging tissue pH by MRI.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
chemical exchange saturation transfer (CEST)
pHresponsive
lanthanide complexes
MRI contrast agents
Megjelenés:Angewandte Chemie-International Edition. - 56 : 52 (2017), p. 16626-16630. -
További szerzők:Martins, André F. Zhao, Piyu Wu, Yunkou Tircsó Gyula (1977-) (vegyész, kémia tanár) Sherry, A. Dean
Pályázati támogatás:GINOP-2.3.2-15-2016-00008
GINOP
K16 120224
OTKA
TheHungarian Academy of Sciences (J#nos Bolyai Research Scholarship)
Egyéb
National Institutes of Health (P41- EB015908, R01-DK095416, and in part by the Harold C. Simmons Cancer Center through an NCI Cancer Center Support Grant, 1P30-CA142543),
Egyéb
Robert A. Welch Foundation (AT-584)
Egyéb
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