RESUMO
Soluble and insoluble polysaccharides were derivatized with diethylenetriaminepentaacetic acid (DTPA) and/or spin-labeled with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). Polysaccharides derivatized with DTPA were prepared via cyanogen bromide activation, coupling to a diamine linker, and to DTPA anhydride. Spin-labeled polysaccharides were also prepared via cyanogen bromide activation. The extent of derivatization for dextran (18 kDa) was about 120 glucose units per DTPA, and for cellulose and starch about 15-30 units per DTPA. For spin-labeled polysaccharides, the average loading ranged from 1 nitroxide per 16 glucose units for starch to 181 for dextran (82 kDa). These derivatized paramagnetic polysaccharides were shown to be more effective relaxants than the small paramagnetic molecules alone. Both soluble and insoluble polysaccharide-linker-DTPA-Gd(III) complexes were effectively cleared from the body (rats) after oral administration. After intravenous administration, the biodistribution of dextran-linker-DTPA-Gd(III) complexes differed significantly from that of GdDTPA. Reduction of the nitroxide by ascorbic acid was retarded in the polysaccharide derivatives, particularly in starch derivatized with both nitroxide and linker-DTPA-Cu(II). These agents showed contrast enhancement in the gastrointestinal tract of rabbits.
Assuntos
Quelantes , Meios de Contraste , Óxidos N-Cíclicos , Imageamento por Ressonância Magnética , Metais , Ácido Pentético , Polissacarídeos , Marcadores de Spin , Animais , Celulose , Quelantes/química , Meios de Contraste/química , Óxidos N-Cíclicos/química , Dextranos , Diaminas/química , Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Masculino , Metais/química , Óxidos de Nitrogênio/química , Ácido Pentético/química , Polissacarídeos/química , Coelhos , AmidoRESUMO
Monocationic 99mTc-nitrido complexes of a variety of diphosphine ligands have been prepared and the in vivo distribution of such cations has been examined in Sprague-Dawley rats. These complexes show initially high myocardial uptake with subsequent wash-out in this animal model. The lack of myocardial retention can be attributed to the facile in vivo reduction of these cations.
Assuntos
Coração/diagnóstico por imagem , Compostos de Organotecnécio , Fosfinas , Animais , Cromatografia em Camada Fina , Ligantes , Lipídeos/química , Masculino , Cintilografia , Ratos , Ratos Endogâmicos , Distribuição TecidualRESUMO
Magnetite (Fe3O4) particles 0.1-0.5 microns in diameter doped with either 99mTc or 111In have been prepared and characterized by electron microscopy and Mössbauer spectroscopy. The time courses of their distributions after injection into rats were determined, including studies by gamma-camera imaging; the main targets were the liver and lung. The radiolabelled magnetic agents may be of value in research studies combining radio- and magnetic resonance imaging procedures.
