Quantitative cerebral magnetic resonance imaging during ACTH treatment of multiple sclerosis

Serial MR scans were performed with the 2DFT imaging method and the filtered backprojection imaging method on 12 patients with multiple sclerosis in acute phase, 4 in a relapsing/remitting form, and 8 in a progressive form, before, during and after ACTH treatment. Both T₁ and T_2mono relaxation times, obtained by fitting transverse magnetization decay curves with a monoexponential function within the apparently normal white matter and the areas of increased signal, were measured. With the backprojection method it was possible to fit the transverse magnetization decay curve with a biexponential function and obtain T_2long and T_2short relaxation times. The T_2mono and T₁ relaxation times of the apparently normal white matter were significantly different from those obtained for volunteers, but no significant differences were found before, during, or after treatment. The transverse magnetization decay curves of the areas of increased signal were better fitted by a biexponential function. No significant changes in these relaxation times were observed after ACTH treatment. These results argue against an anti-oedematous action of ACTH and may suggest that it has an immunosuppressant effect.     

Symplectic hypersurfaces in the complement of an isotropic submanifold

Using Donaldson's approximately holomorphic techniques, we construct symplectic hypersurfaces lying in the complement of any given compact isotropic submanifold of a compact symplectic manifold. We discuss the connection with rational convexity results in the K?hler case and various applications. Received: 9 January 2001 / Published online: 19 October 2001     

Oscillations spatio-temporelles engendrees par un automate cellulaire

We study a planar cellular automaton which is a simple model of a reaction-diffusion mechanism in excitable media; we are especially interested in the spatio-temporal organization which it generates. Under suitable assumptions, the sequence of the states of the plan is ultimately either stationary or periodic. In the latter case, we prove that there exists only one admissible period which is independent of the initial conditions and that a spatial organization of the plan appears, consisting of parallel equidistant target-wave-fronts growing with constant speed.     

Etude de la racemisation induite par la dmap dans les reactions de couplage peptidique

The scope and limitation for the use of 4-dimethylamino pyridine (DMAP) as additive to carbodiimides in peptide synthesis are studied and compared with the results obtained with H-hydroxybenzotriazole (HOBt). The activation of N-acylated aminoacids by the means of DMAP leads to a complete racemization. On the other hand, for the aminoacids protected under their urethans derivatives, DMAP gives better yields than HOBt with racemization extent generally equal to or slightly higer to that observed with HOBt.     

Independance lineaire des valeurs des solutions transcendantes de certaines equations fonctionnelles

Sans résumé     

Induction asymetrique—II: Determination des configurations relatives de δ-amino β-hydroxyesters diastereoisomeres,obtenus par la reaction de reformatsky

Addition of Reformatsky reagents (R₁-CHZnBr-CO₂R) to three β-aminoketones, yields mixtures of threo and erythro diastereomeric aminohydroxyesters. The relative configurations of the first members of each series (R₁CH₃), were determined by chemical correlation. Those of higher homologues (R₁C₂H₅, iC₃H₇,tC₄H₉) are assigned by a study of their NMR spectra.