[Biodistribution of new polynitroxides using electron paramagnetic resonance]. / Biodistribution de nouveaux polynitroxydes par résonance paramagnétique électronique.

The most important paramagnetic contrast agents used in Nuclear Magnetic Resonance Imaging are limited to a few metal complexes such Gd-DTPA or stable free radicals such as nitroxides simply functionalized. We studied the biodistribution of new polynitroxides agents by Electronic Paramagnetic Resonance in Sprague Dawley rats. Three of the six different polynitroxides agents studied, showed an interesting and selective localisation in the lungs, heart and liver.

[Unidimensional imaging. A simple method for evaluating the efficacy of a contrast agent in magnetic resonance imaging. Application of new nitroxides]. / L'imagerie unidimensionnelle. Une méthode simple pour évaluer l'efficacité d'un agent de contraste en imagerie par résonance magnétique. Application à de nouveaux nitroxydes.

We present an experimental set-up of one-dimension imaging which permits on a conventional NMR spectrometer, to measure the difference in relaxation time T1 of two organ samples, one normal and the other injected with a contrast agent. Using that technique and M.R.I. two new nitroxides reveal a substantial contrast effect for kidneys and heart.

Precise characterization of cuticular compounds in youngDrosophila by mass spectrometry.

Cuticular hydrocarbons of youngDrosophila flies are singular with very long chains and complex diene mixtures. A precise characterization of these substances was carried out by epoxidation and analysis of the products by GC-MS with negative chemical ionization. InD. melanogaster, double bonds of dienes are more probable at carbon positions 11 or 13 and 21 or 23. InD. simulans, double bonds are shifted more towards the interior of the chain. Such a difference is also found among monoenes of both species. The analyses of monoenes and dienes confirm the similarity of cuticular compounds of young flies of both sexes in both species. A main cuticular compound ofD. erecta females, 9, 23-tritriacontadiene, is also presented.

A further characterization of Drosophila cuticular monoenes using a mass spectrometry method to localize double bonds in complex mixtures.

Positions of double bonds of olefins of complex mixtures, such as those of Drosophila cuticular hydrocarbons, have been determined using a simple method combining methoxymercuration-demercuration of extracts and analysis by gas chromatography-mass spectrometry using ammonia for chemical ionization. Chemical similarities between cuticular monoenes of both sexes of Drosophila simulans and males of Drosophila melanogaster are specified: the major isomer is always in position 7.

Compared behavioral responses of maleDrosophila melanogaster (Canton S) to natural and synthetic aphrodisiacs.

Cuticular aphrodisiacs fromD. melanogaster females were further characterized and the male response specificity towards such natural and synthetic unsaturated hydrocarbons was investigated. The behavioral activity seems to be correlated with some chain-length requirement and double-bond position; at least one double bond in position 7 seems necessary. This position is more abundant among natural monoenes, and among dienes which also bear a second double bond in position 11, whatever the chain length. Bioassays of the synthetic (Z,Z)-7,11-heptacosadiene yielded a dose-response curve close to that of the natural mixture of heptacosadienes in which the 7-11 isomer is predominant. This female specific 7,11 heptacosadiene appears to be the most potent aphrodisiac for males of the species. Its threshold is lower than that of both 7,11-nonacosadiene and 7-pentacosene which might also play a role in sex and species recognition.