Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 3 de 3
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Magn Reson Chem ; 46 Suppl 1: S86-93, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18855344

RESUMO

The Gd(III) complexes of three new octadentate chelators, prepared by substitution of four, two, and one carboxylate groups of EGTA with phosphonate groups, have been investigated by 1H and 17O NMR relaxometric techniques in aqueous solutions. The analysis of the solvent proton relaxivity data as a function of pH, temperature, and magnetic field strength (nuclear magnetic relaxation dispersion (NMRD) profiles) in combination with the 17O transverse relaxation rate data at variable temperature allowed assessing the hydration state of the complexes, the occurrence of pH-dependent oligomerization processes for the tetraphosphonate derivative, the presence of a well-defined second sphere of hydration that markedly contributes to the relaxivity, and the values of the structural and dynamic relaxation parameters. In addition, in the case of the monophosphonate derivative the presence of a coordinated water molecule has allowed evaluation of the kinetic parameters of the exchange process, highly relevant for the possible use of this Gd(III) complex as an MRI probe. The rate of exchange of the water molecule, (298)k(ex) = 4.2 x 10(8)s(-1), is one of the highest measured so far for a nonacoordinate Gd(III) chelate and optimal for developing contrast-enhancing probes of high efficacy at high magnetic fields.


Assuntos
Ácido Egtázico/análogos & derivados , Gadolínio/química , Espectroscopia de Ressonância Magnética/métodos , Organofosfonatos/química , Água/química , Meios de Contraste/química , Cinética , Compostos Organometálicos/química , Isótopos de Oxigênio , Soluções
2.
Neoplasia ; 9(12): 1046-56, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18084612

RESUMO

Gd-DO3A-diph and Gd-AAZTAC17 are lipophilic magnetic resonance imaging (MRI) agents that display high affinity for low-density lipoprotein (LDL) particles. However, on binding to LDL, Gd-DO3A-diph shows a decreased hydration that results in a lower enhancement of water proton relaxation rate. Conversely, Gd-AAZTAC17 displays a strong relaxation enhancement at the imaging fields. Each LDL particle can load up to 100 and 400 UNITS of Gd-DO3A-diph and Gd-AAZTAC17, respectively. Their LDL adducts are taken up by human hepatoblastoma G2 (HepG2) and melanoma B16 tumor cells when added to the incubation medium. T(1) measurements of the labeled cells indicate that Gd-AAZTAC17 is significantly more efficient than Gd-DO3A-diph. Furthermore, it has been found that HepG2 hepatoma cells can internalize higher amounts of Gd-AAZTAC17 than B16 cells and the involvement of LDL receptors (LDLRs) has been demonstrated in competition assays with free LDL. Gd-AAZTAC17/LDL adduct proved to be an efficient probe in the magnetic resonance (MR) visualization of subcutaneous tumors in animal models obtained by injecting B16 melanoma cells into the right flank of mice. Finally, confocal microscopy validation of the distribution of LDL-based probes in the tumor has been obtained by doping the Gd-AAZTAC17/LDL adduct with a fluorescent phospholipid moiety.


Assuntos
Meios de Contraste/análise , Lipoproteínas LDL/administração & dosagem , Imageamento por Ressonância Magnética/métodos , Ressonância Magnética Nuclear Biomolecular/métodos , Compostos Organometálicos/análise , Receptores de LDL/análise , Animais , Carcinoma Hepatocelular/química , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral/química , Linhagem Celular Tumoral/transplante , Colorimetria , Portadores de Fármacos , Humanos , Bicamadas Lipídicas , Lipoproteínas LDL/farmacocinética , Neoplasias Hepáticas/química , Neoplasias Hepáticas/patologia , Melanoma Experimental/química , Melanoma Experimental/patologia , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Confocal/métodos , Transplante de Neoplasias , Compostos Organometálicos/síntese química , Compostos Organometálicos/farmacocinética , Tamanho da Partícula , Ligação Proteica , Receptores de LDL/efeitos dos fármacos , Organismos Livres de Patógenos Específicos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...