[en] Short communication. 1 ref

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[en] Cyclo-dextrins are cyclic oligosaccharides which contain six (α, seven (β) or eight (γ) glucose units bound by α bonds. These molecules are bio-compatible, soluble in water and can incorporate organic substrates in their lipophilic cavity. The chemical modification of these natural cyclo-dextrins to give per-3,6-anhydro derived compounds changes radically the structure of the receptor and give a hydrophilic cavity. This inversion of the inclusion properties allows to obtain compounds able to bind the metallic ions. In order to reinforce the affinity of these molecules towards hard metallic cations, the residual hydroxyl groups (position 2) have been substituted by carboxy-methyl groups to obtain ACX (α) and BCX (β) cyclo-dextrins. The properties of these new compounds will be presented. The ACX and BCX ligands form mono-metallic and bimetallic complexes with lanthanides (III) in aqueous solution. The structure at the solid state of the compound [Lu₂(ACX)(H₂O)₂] represents the first example of lanthanide-cyclo-dextrin inclusion complex. Indeed, each Lu(III) cation is encapsulated in the cavity and interacts both with carboxylate groups and the ether oxygens of the cyclo-dextrin. At last, the nuclear relaxation properties of the gadolinium(III) mono-metallic complexes will be discussed. (O.M.)

[en] This paper presents the views of a coordination chemist on the synthesis and the properties of new contrast agents containing gadolinium. Attention is drawn to various macrocyclic complexes such as the polyaza polycarboxylic chelates, the cryptates as well as compounds obtained by template synthesis. The structural factos influencing the kinetic and thermodynamic stability of the gadolinium complexes are discussed with special emphasis on the polyaza polycarboxylic derivatives. Some of the macrocyclic complexes under investigation are more stable than Gd-DTPA. (author)

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[en] A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in the cavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexes show irreversible one electron reduction process around -2.15 to -1.60 V. The reduction potential of gadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. The catalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determined. All gadolinium(III) complexes were screened for antibacterial activity

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[en] Eleven clinical cases successfully underwent MR guided needle puncture and tissue sampling using 0.35 T open MR unit; OPART. A 55 cm opening and MR fluoroscopy was useful to optimize the plane for monitoring the procedure for each case. Even with inadequate time resolution and still limited space, the method was comparable to CT or US guided procedures for some selected indications, because it has multi-plane monitoring capability, no X-ray irradiation and a potential for multi-parameter image monitoring such as T1-, T2, T2^*- and temperature. Thus we expect the optimistic future for MR guided procedures with software and hardware evolutions. (author)