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Magnetic Resonance Contrast Agents (magnetic + resonance_contrast_agent)
Selected AbstractsN -(2-Hydroxypropyl)methacrylamide (HPMA) Copolymer-Linked Nitroxides: Potential Magnetic Resonance Contrast AgentsMACROMOLECULAR BIOSCIENCE, Issue 11 2003Yuan Huang Abstract N -(2-Hydroxypropyl)methacrylamide (HPMA) copolymer-linked nitroxides were synthesized as macromolecular contrast agents for MR imaging. Molar relaxivities of HPMA copolymer-linked nitroxides increased linearly in proportion to the number of nitroxides attached per gram of copolymer. HPMA copolymer-linked nitroxides with 15, 20 and 30 mol-% nitroxide exhibited higher relaxivities than gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA). These results demonstrate the potential of HPMA copolymer-linked nitroxides as MR contrast agents for solid tumors. Structure of HPMA copolymer-linked nitroxides. [source] Tyrosine polyethylene glycol (PEG)-micelle magnetic resonance contrast agent for the detection of lipid rich areas in atherosclerotic plaqueMAGNETIC RESONANCE IN MEDICINE, Issue 5 2009Anne Beilvert Abstract Vulnerable or high-risk atherosclerotic plaques often exhibit large lipid cores and thin fibrous caps that can lead to deadly vascular events when they rupture. In this study, polyethylene glycol (PEG)-micelles that incorporate a gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) amphiphile were used as an MR contrast agent. In an approach inspired by lipoproteins, the micelles were functionalized with tyrosine residues, an aromatic, lipophilic amino acid, to reach the lipid-rich areas of atherosclerotic plaque in a highly efficient manner. These micelles were applied to apolipoprotein E,/, (ApoE,/,) mice as a model of atherosclerosis. The abdominal aortas of the animals were imaged using T1 -weighted (T1W) high-resolution MRI at 9.4T before and up to 48 h after the administration of the micelles. PEG-micelles modified with 15% tyrosine residues yielded a significant enhancement of the abdominal aortic wall at 6 and 24 h postinjection (pi) as compared to unmodified micelles. Fluorescence microscopy on histological sections of the abdominal aorta showed a correlation between lipid-rich areas and the distribution of the functionalized contrast agent in plaque. Using a simple approach, we demonstrated that lipid-rich areas in atherosclerotic plaque of ApoE,/, mice can be detected by MRI using Gd-DTPA micelles. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] Gadolinium-Induced Nephrogenic Systemic Fibrosis Is Associated with Insoluble Gd Deposits in Tissues: In Vivo Transmetallation Confirmed by MicroanalysisJOURNAL OF CUTANEOUS PATHOLOGY, Issue 12 2009Charu Thakral Background: Nephrogenic systemic fibrosis (NSF) is an extremely debilitating systemic fibrosing disorder affecting renal failure patients. The association of NSF with gadolinium (Gd) containing magnetic resonance contrast agents was noted in 2006. Gd deposition in skin biopsies was demonstrated shortly thereafter. Methods: We used automated scanning electron microscopy (SEM)/energy dispersive x-ray spectroscopy for in situ quantitative analysis of insoluble Gd-containing deposits, recording multi-elemental composition and spatial distribution of detected features. Results: Gd was detected in all 29 patients (53 of 57 skin biopsies) with NSF, biopsied from 2 weeks to 3 years after Gd exposure. Gd concentration ranged from 1 to 2270 cps/mm2 and was detected predominantly in the deep dermis and subcutaneous fibrous septa. Gd was found associated with Ca, P and sometimes Fe or Zn. Patients with sequential biopsies showed persistence or increase of Gd in tissues (6 of 11). Transmission electron microscopy (TEM) identified the intracellular deposits in fibrocytes and macrophages. Conclusions: The demonstration of insoluble tissue deposits of Gd with co-associated elements clearly confirms in vivo transmetallation and dissociation of soluble Gd-chelates. Toxic Gd3+ may trigger fibrosis under permissive conditions, e.g., in renal insufficiency. Pathologists and clinicians need to be aware of this serious but preventable disease. [source] Comparison of HPLC and CZE methods for analysis of DOTA-like esters , reaction intermediates in synthesis of magnetic resonance contrast agentsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4-5 2010Anna Hamplová Abstract RP-HPLC and non-aqueous CZE methods were evaluated for qualitative and quantitative analysis of esterified macrocyclic compounds of the DOTA family (DOTA=1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid). This group of compounds represents important reaction intermediates in synthesis of magnetic resonance contrast agents. Calibration curves in the concentration range from 1.0×10,5 to 1.0×10,3,mol/L were plotted and the experimental data were critically compared in terms of their repeatability, linearity, LOD and LOQ. The optimized methods were successfully applied to the analysis of a real reaction mixture without any further pretreatment. [source] Design of (Gd-DO3A)n -polydiamidopropanoyl-peptide nucleic acid- D(Cys-Ser-Lys-Cys) magnetic resonance contrast agentsBIOPOLYMERS, Issue 12 2008Nariman V. Amirkhanov Abstract We hypothesized that chelating Gd(III) to 1,4,7-tris(carboxymethylaza)cyclododecane-10-azaacetylamide (DO3A) on peptide nucleic acid (PNA) hybridization probes would provide a magnetic resonance genetic imaging agent capable of hybridization to a specific mRNA. Because of the low sensitivity of Gd(III) as an magnetic resonance imaging (MRI) contrast agent, a single Gd-DO3A complex per PNA hybridization agent could not provide enough contrast for detection of cancer gene mRNAs, even at thousands of mRNA copies per cell. To increase the Gd(III) shift intensity of MRI genetic imaging agents, we extended a novel DO3An -polydiamidopropanoyl (PDAPm) dendrimer, up to n = 16, from the N-terminus of KRAS PNA hybridization agents by solid phase synthesis. A C-terminal D(Cys-Ser-Lys-Cys) cyclized peptide analog of insulin-like growth factor 1 (IGF1) was included to enable receptor-mediated cellular uptake. Molecular dynamic simulation of the (Gd-DO3A-AEEA)16 -PDAP4 -AEEA2 - KRAS PNA-AEEA- D(Cys-Ser-Lys-Cys) genetic imaging nanoparticles in explicit water yielded a pair correlation function similar to that of PAMAM dendrimers, and a predicted structure in which the PDAP dendron did not sequester the PNA. Thermal melting measurements indicated that the size of the PDAP dendron included in the (DO3A-AEEA)n -PDAPm -AEEA2 - KRAS PNA-AEEA- D(Cys-Ser-Lys-Cys) probes (up to 16 Gd(III) cations per PNA) did not depress the melting temperatures (Tm) of the complementary PNA/RNA hybrid duplexes. The Gd(III) dendrimer PNA genetic imaging agents in phantom solutions displayed significantly greater T1 relaxivity per probe (r1 = 30.64 ± 2.68 mM,1 s,1 for n = 2, r1 = 153.84 ± 11.28 mM,1 s,1 for n = 8) than Gd-DTPA (r1 = 10.35 ± 0.37 mM,1 s,1), but less than that of (Gd-DO3A)32 -PAMAM dendrimer (r1 = 771.84 ± 20.48 mM,1 s,1) (P < 0.05). Higher generations of PDAP dendrimers with 32 or more Gd-DO3A residues attached to PNA- D(Cys-Ser-Lys-Cys) genetic imaging agents might provide greater contrast for more sensitive detection. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 1061,1076, 2008. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] | |||||||||||||