Jacques Delforge

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A new simple method is proposed to detect, using PET and [(11)C]raclopride, changes in striatal extracellular dopamine concentration during a rewarded effortful task. This approach aimed to increase the sensitivity in detection of these effects. It requires a single-dynamic PET study and combines the classic kinetic compartmental model with the general(More)
The regulation of arginine biosynthetic enzymes in yeast is subjected to a double control. One level of arginine enzyme synthesis is under the control of an apo-repressor, called ARGR. ARGR molecules control specifically the arginine pathway. A second level of control of arginine biosynthesis has been disclosed. It also controls tryptophan, histidine,(More)
A kinetic method using a multiinjection protocol, positron emission tomography (PET), and [11C]flumazenil as a specific ligand was used to study in vivo the flumazenil-benzodiazepine receptor interactions in the human brain. The model structure is composed of three compartments (plasma, free, and bound ligand) and five parameters (including the(More)
The multi-injection approach has been used to study in baboon the in vivo interactions between the D2 receptor sites and FLB 457, a ligand with a very high affinity for these receptors. The model structure was composed of four compartments (plasma, free ligand, and specifically and unspecifically bound ligands) and seven parameters (including the D2(More)
The identification of the model parameters from data obtained with a single tracer injection leads to disappointing numerical results, since most of the parameters have to be considered as unidentifiable. A protocol including two injections, a first injection of the labeled ligand and a second injection of the cold ligand (displacement experiment), leads to(More)
UNLABELLED In vivo quantification of receptor concentration and ligand affinity using data obtained with PET is based on the compartmental analysis of ligand-receptor interactions. There is, however, an inconsistency between the assumed homogeneity of the ligand concentration in each compartment, a basic hypothesis of the compartmental analysis, and the(More)
Receptor density and ligand affinity can be assessed using positron emission tomography (PET). Biological parameters (B(max)('), k(1), k(2), k(on)/V(R), k(off)) are estimated using a compartmental model and a multi-injection protocol. Parametric imaging of the ligand-receptor model has been shown to be of special interest to study certain brain disorders.(More)
We have undertaken a test-re-test [11C]flumazenil (FMZ) PET study in 10 drug-resistant epileptic patients, including six with a mesiotemporal epilepsy (MTE), and 10 normal controls, in order to investigate seizure-related short-term plasticity of benzodiazepine (BZD) receptors. All subjects underwent two FMZ-PET scans at a 1 week interval. Patients(More)
The results of several recent papers have shown a significant influence of the endogenous neurotransmitters on the exogenous ligand kinetics measured by positron emission tomography. For example, several groups found that the percentage of D2 receptor sites occupied by the endogenous dopamine ranged from 25% to 40% at basal level. An obvious consequence of(More)