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81.
Woods M Zhang S Ebron VH Sherry AD 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(19):4634-4640
The lanthanide(III) complexes of three tetraamide DOTA bearing pyridyl, phenolic and hydroxypyridyl substituents have been studied by NMR, luminescence and cyclic voltammetry. The relaxivity profiles of the gadolinium complexes of the pyridyl and phenolic ligands were flat and essentially the same between pH 2 and 8. The hydroxypyridyl ligand, however, exhibited two regions of enhanced relaxivity. The small relaxivity enhancement (25 %) at lower pH (pH 2-4) has been attributed to an increase in the prototropic exchange of the coordinated water molecule while the slightly larger enhancement (84 %) at higher pH (pH 6-9) reflects deprotonation of the ligand amide protons. Deprotonation of the amides results in the formation of an intramolecular acid-base pair interaction with the phenolic protons and this, in turn, causes a highly organized second hydration sphere to come into effect, thereby increasing the relaxivity. The water relaxivity of the Gd(3+)-hydroxypyridyl complex is further enhanced upon binding to serum albumin. 相似文献
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Isaac Zigelboim Daniel Offen Eldad Melamed Hana Panet Moshe Rehavi Yoram Cohen 《Journal of inclusion phenomena and macrocyclic chemistry》2007,59(3-4):323-329
Although magnetic resonance imaging (MRI) is one of the most important imaging modalities of the central nervous system (CNS),
one of the main drawbacks of MRI is its limited specificity. This can potentially be partially alleviated by target-specific
contrast agents. In the present paper we describe a simple high yield synthesis of two such gadolinium-based spiperone targeted
MRI contrast agents, 1a and 1b. The R1 relaxivities of 1a and 1b were evaluated and found to be 5.94 and 8.31 mM−1 s−1, respectively at 9.4T, while their R2 relaxivities at the same magnetic field were found to be 18.05 and 22.60 mM−1 s−1, respectively. In addition and very importantly compound 1a, which is a gadolinium-based, spiperone-targeted MRI contrast agent, was found to preserve some of the spiperone affinity
toward the dopamine D2 receptor. Compounds 1a and 1b thus represent potential agents for in vitro dopamine receptor imaging using MRI in experimental models.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
84.
In recent years scanning near-field optical microscopy (SNOM) has developed into a powerful surface analytical technique for observing specimens with lateral resolution equal to or even better than 100 nm. A large number of applications, from material science to biology, have been reported. In this paper, two different kinds of near-field optical microscopy, aperture and scattering-type SNOM, are reviewed together with recent studies in surface analysis and biology. Here, near-field optical techniques are discussed in comparison with related methods, such as scanning probe and standard optical microscopy, with respect to their specific advantages and fields of application. 相似文献
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本文探讨了计算机断层扫描(CT)、磁共振成像(MRI)对良恶性甲状腺结节的鉴别价值。方法:选取2015年3月至2018年3月本院收治的甲状腺结节患者150例,依据病理结果分为恶性48例、良性102例,所有患者均给予CT、MRI检查,分析CT、MRI对良恶性甲状腺结节的鉴别价值。结果发现,MRI总病灶、形态不规则、边界不清/毛糙、信号/密度不均检出率明显高于CT,MRI钙化灶检出率明显低于CT,差异有统计学意义(P<0.05),CT、MRI淋巴结转移检出率比较,差异无统计学意义(P>0.05);在鉴别良恶性甲状腺结节的敏感度、特异度、准确度中,CT为79.17%、74.51%、76.00%,MRI为83.33%、80.39%、81.33%,CT联合MRI为95.83%、96.08%、96.00%,CT联合MRI明显高于CT、MRI,差异有统计学意义(P<0.05)。说明CT、MRI可作为鉴别良恶性甲状腺结节的重要方法,CT对钙化灶有较高的分辨能力,MRI对软组织及小病灶有较高的分辨能力,CT联合MRI可有效提高其鉴别价值。 相似文献
89.
K. Asami 《Colloid and polymer science》1998,276(4):373-378
A dielectric imaging technique with a scanning dielectric microscope was applied to polystyrene microcapsules in an aqueous
environment to study the electrical properties of individual ones. The dielectric images obtained over a frequency range from
10 kHz to 10 MHz showed frequency dependence, which indicated dielectric dispersion (or relaxation) due to interfacial polarization
or the build up of charge on the boundaries between the microcapsule shell and the aqueous phases. The dielectric dispersion
was analyzed based on an equivalent electrical circuit model and a shell-sphere model in which a spherical core is covered
with an insulating shell.
Received: 26 September 1997 Accepted: 26 December 1997 相似文献
90.
Chieu D. Tran Dora Ilieva Santhosh Challa 《Journal of Sol-Gel Science and Technology》2004,32(1-3):207-217
Concentration distributions and conformations of bovine serum albumin (BSA) entrapped in sol–gels were successfully determined for the first time by use of the recently developed NIR multispectral imaging instrument. It was found that BSA molecules were inhomogeneously distributed within the sol–gel matrix, independent of its concentration. At relatively high concentration (366 mg/mL) the encapsulation process does not seem to produce any observable changes in the conformation of BSA. However, when the concentration of BSA was decreased to 220 mg/mL, pronounced changes in the spectra of the protein were observed as a function of (sol–gel reaction) time. The observed inhomogenity might be traced to both a non-uniform concentration distribution of BSA and changes in protein native conformation resulting from interactions between the charged protein and the silicate anions. Results obtained seem to suggest that the protein molecules might adapt themselves to accommodate evolving geometry and sites of the silica network. 相似文献