cis-UROCANIC ACID FAILED TO AFFECT in vitro HUMAN LANGERHANS CELL ALLOSTIMULATORY FUNCTION

Abstract— -Urocanic acid (UCA) represents the major ultraviolet B (UVB, 290–320 nm)-absorbing component of the skin. Trans-UCA is naturally produced in the stratum corneum and converts to the cis isomer upon UVB irradiation. In this study, we examined the effect of purified cis -UCA (about 99% of cis isomer) on the human Langerhans cell (LC) allostimulatory function by using the mixed epidermal cell-lymphocyte reaction (MELR). We found that addition of increasing amounts (6.5–400 μg/mL) of purified cis-UCA or (rara-UCA did not modify the T-cell response supported by enriched LC (eLC: 8–25% LC) as well as purified LC (pLC: 70–90% LC) suspensions. Because cis-UCA had no effect on the allostimulatory function of untreated LC, we investigated whether this compound could modify T-cell proliferation induced by UVB-irradiated LC. The UVB exposure of eLC or pLC to 100 J/m² significantly inhibited the capacity of both suspensions to mount a T-cell response. However, addition of cis- UCA did not potentiate this UVB-induced immunosuppression. The eLC or pLC were then incubated with cis-UCA for 18 h at 37°C and washed before adding to allogeneic T cells. The obtained proliferative response was similar to that induced by control LC incubated in medium alone, demonstrating that pretreatment with cis -UCA did not alter human LC function. In conclusion, these results strongly suggest that cis-UCA has no direct effect on human LC antigen-presenting function.     

Differentiation of isomeric 5- and 7-oxo derivatives of tetrahydrothiazolo[3,2-a]pyrimidine by electron impact mass spectrometry

The electron impact mass spectra of two series of 5-oxo-tetrahydro-5H-thiazolo [3,2-a]pyrimidine-6-ethylcarboxylates and 7-oxo-tetrahydro-7H-thiazolo [3,2-a]pyrimidine-6-ethylcarboxylates were measured and fragmentation patterns examined. Structures were assigned from analysis of oxo molecular ion fragmentations. Compounds of the 5-oxo series gave an [M – CO₂C₂H₅]⁺ fragmentation whereas compounds of the 7-oxo series gave three characteristic cleavages. This decomposition was confirmed for one pair of isomers by high-resolution mass spectrometry and unimolecular mass-analysed ion kinetic energy spectrometry. Electron impact mass spectrometry is a convenient method for assigning structures of 5- and 7-oxo regioisomers of tetrahydrothiazolo[3,2-a]pyrimidine-6-carboxylates.     

Etude par spectrométrie de masse de la fragmentation des cyclopentane-triols-1,2,3, des cyclopentane-tétrols et des cyclopentane-pentols

The mass spectra of the three cyclopentane-1,2,3-triols, six cyclopentane-tetrols and four cyclopentane-pentols stereoisomers have been studied. Complex processes, especially regarding the H₂O eliminations, were detected by extensive deuterium labelling.     

Preparation d'esters par deshydrogenation d'alcools primaires en phase liquide catalysee par l'oxyde de cuivre - observations preliminaires

Linear primary alcohols with at least 7 carbon atoms are quite quantitatively transformed in esters, by CuO, at temperatures > 170°, without air in liquid phase. Preponderant influence of carbon in position 2 is evidenced. In the same conditions lactones are obtained from diols, and benzylic alcohols undergoes, by hydride transfer, a disproportionation into toluene, benzaldehyde and water.     

Study of the ternary system FeCrTe around the composition FeCr2Te4

The system FeCrTe was investigated around the composition FeCr₂Te₄. FeCr₂Te₄ is a metastable compound. Single crystals with Fe_0·93Cr_1·76Te₄ composition were grown by vapor transport or the Bridgman method. These crystals are metallic and anisotropic ferromagnets.     

The thermodynamic properties of acetals+heptane mixtures at 298.15 K

Excess enthalpies and excess volumes were determined at 298.15 K for: dimethoxymethane+heptane, diethoxymethane+heptane, 1,1-dimethoxyethane+heptane, 1,1-diethoxyethane+heptane, 2,2-dimethoxypropane+heptane and 1,1-diethoxypropane+heptane.     

Syntheses du tri-O-benzyl-3,4,6-D-glucal

The synthesis of 3,4,6 tri-O-benzyl-D-glucal (4) has been accomplished by direct benzylation of triacetylglucal (yield 55%) and by zinc reduction of 3,4,6-tri-O-henzyl-2-acetoxy-1-bromoglucose (yield 26%). The nmr spectra of tribenzyl- and triacetyl-D-glucal in the presence of lanthanide shift reagents were reported.     

Elasticity and electro-magneto-elasticity of general-relativistic systems

This essay aims at demonstrating the interest for a genuine continuum mechanics and, more restrictively, elasticity of general-relativistic systems in cases where the Einsteinian gravitational picture cannot be deleted, e.g., in elastic gravitational-wave detectors and in the study of elastic oscillations of solid stars. The same foundations, constitutive theory, and methodology (superimposition of perturbations on finite initial states) apply to both cases, which also demand a generalization to comprehend electrodynamical-mechanical couplings, electroelasticity in the first case (use of piezoelectricity), and magnetoelasticity in the second case (presence of extremely intense magnetic fields).     

Ion spray-tandem mass spectrometry of supramolecular coordination complexes

Double-helical [M₂L₂] ⁿ⁺, triple-helical [M₂L₃] ⁿ⁺, and toroidal [M₃L₃] ⁿ⁺ (M = Cu, Co, Fe, Ni, La, Eu, Gd, Tb, or Lu) supramolecular complexes have been fully characterized by ion spray mass spectrometry (IS-MS). The IS-MS spectra from pure acetonitrile solutions reflect the nature of the cations present in solution with conservation of the charge state and allow an efficient qualitative speciation of the compounds. The mass spectrometry results can be correlated with other powerful techniques (nuclear magnetic resonance and electronic spectroscopy) for the characterization of supramolecular complexes in solution, Structural information is obtained by collision-induced dissociation, which strongly depends on the metal ions used in the supramolecular complexes and on the various connectivities and topologies of the ligands. When the ligand contains 3,5dimethoxybenzyl groups bound to the benzimidazole rings, the partial fragmentation of the complexes is associated with a decrease of the total charge of the complexes and the appearance of the characteristic fragment at m/z 151 that corresponds to the 3,5-dimethoxybenzyl cation. A detailed analysis of the fragmentation pathways of these supramolecular complexes suggests that the metal-nitrogen coordination bonds are very strong in the gas phase.     

Interactions magnétiques dans des groupements binucléaires du Ruthénium +V

The cationic ordering in the $\text{Ba}\text{M}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Ru}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{O}{}_3\text{(M =}\text{Mg, Ca, Cd, Sr}\text{)}$ oxides which crystallize with the 6H structure gives rise to Ru⁵⁺Ru⁵⁺ pairs in (Ru₂O₉) clusters. The magnetic properties have been analyzed on the basis of the Heisenberg-Dirac-Van Vleck model: The d electrons are localized on each Ru⁵⁺ ion and interact strongly through antiferromagnetic exchange. The susceptibility curves agree with the H.D.V.V. model. The values of the exchange integrals have been determined by fitting the experimental values.