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The unambiguous detection of specific neuronal subtypes is up to now only possible with invasive techniques or optical imaging after genetic modification. High field magnetic resonance imaging (MRI) has the ability to visualize the brain structure and anatomy noninvasively, with high resolution--but missing the cell specific and functional information. Here… (More)
Cells display on the outer surface of the plasma membrane a large number of protein thiols that can be reversibly labelled with suitably designed Gd(III)-based contrast agents for cell tracking by MRI.
The titration curves of the C-2 histidine protons of RNase A and of derivative II--a covalent derivative obtained by reaction of the enzyme with the halogenated nucleotide 9-beta-D-ribofuranosyl-6-chloropurine 5'-phosphate--in the presence of a number of purine nucleosides, nucleoside monophosphates, and nucleoside diphosphates were studied by means of… (More)
Novel contrast agent based systems, which selectively visualize specific cells, e.g., neurons in the brain, would be of substantial importance for the fast developing field of molecular magnetic resonance imaging (MRI). We report here the synthesis and in vitro validation of a Gd(III)-based contrast agent designed to act as an MRI responsive probe for… (More)
This work aims at assessing the in vitro potential of paramagnetic pH sensitive liposomes as imaging tools for visualizing drug-delivery and release processes by Magnetic Resonance Imaging (MRI). pH sensitive liposomes (pSLs) were formulated using the fusogenic phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), the membrane… (More)
The titration curves of the C-2 histidine protons of an RNAase derivative (a covalent derivative obtained by reaction of bovine pancreatic RNAase A (EC 18.104.22.168) with 6-chloropurine 9-beta-D-ribofuranosyl 5'-monophosphate) were studied by means of 1H-NMR spectroscopy at 270 MHz. The interaction of natural (5'AMP, 5'GMP, 5'IMP) and halogenated purine… (More)
Four novel MRI Gd(III)-based probes have been synthesized and evaluated for their labeling properties on cultured cell lines K562, C6, and B16. The labeling strategy relies upon the fact that cells display a large number of reactive exofacial protein thiols (EPTs) that can be exploited as anchorage points for suitably activated MRI probes. The probes are… (More)
Accurate measurement of the tissue pH in vivo by MRI may be of clinical value for both diagnosis and selection/monitoring of therapy. To act as pH reporters, MRI contrast agents have to provide responsiveness to pH that does not require prior knowledge of the actual concentration of the contrast agent. This work deals with the use of a paramagnetic… (More)
The sensitivity of magnetic resonance imaging (MRI) contrast agents is highly dependent on the rate of water exchange between the inner sphere of a paramagnetic ion and bulk water. Normally, identifying a paramagnetic complex that has optimal water exchange kinetics is done by synthesizing and testing one compound at a time. We report here a rapid,… (More)
The solid-phase synthesis of several analogs of enkephalin containing gamma-amino-butyric acid is reported. Synthetic strategies, purification methods, chemical and physicochemical characterization are discussed. The n.m.r. data suggest for some of the analogs structural features similar to the opioids.