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B Gallez

Publications and source records attributed to B Gallez.

4 recordsLinked to original sources
PubMed1992

Mutagenicity of nitroxyl compounds: structure-activity relationships.

Three piperidinoxyl radicals were found to be directly mutagenic in Salmonella typhimurium TA 100, one pyrrolidinoxyl compound had weaker activity, and two other pyrrolidinoxyl derivatives did not produce an increase of the spontaneous revertants. The tester strain TA 100 was selected in preliminary tests for its higher sensitivity compared to TA 98 and TA 102. The mutagenic activity of the three active compounds was abolished by partial reduction with ascorbic acid, suggesting that the mutagenicity was linked to the free radical nature of these compounds, and reduced in the presence of a cofactor supplemented rat liver subcellular fraction. The mutagenicity of the tested compounds was correlated to the resistance of the nitroxyl spin labels to reduction: the more reactive radicals were found to possess higher mutagenic activity.

Ascorbic Acid↗
PubMed1992

Evaluation of nonionic nitroxyl lipids as potential organ-specific contrast agents for magnetic resonance imaging.

Considering their intrinsic properties of accumulation in the hepatic tissue, we have synthesized nitroxyl-containing lipids as potential organ-specific contrast agents for magnetic resonance imaging (MRI). Their resistance to reduction by ascorbate and in liver homogenates, and their relaxivity in different media were investigated and compared to those of free carboxyl-Proxyl (3-carboxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl) and Tempamaine (4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl). With respect to the reduction rates by ascorbate, the lipid derivatives show the same well-known order of reactivity as carboxy-Proxyl and Tempamine, the five-membered nitroxyls being more stable than the six-membered compounds. However the binding of the piperidinoxyl compounds to the fatty acids confers to those lipid derivatives a markedly increased stability. Similarly, in liver homogenates, the nitroxyl lipids remained unchanged more than 20 min, contrarily to carboxy-Proxyl and Tempamine. The measurements of spin-lattice relaxation time (T1) in biological media have demonstrated a higher relaxivity of nitroxyl lipids, which can be related to their interaction with proteins. Tested in vivo, one of the synthesized compounds (0.75 mmol/kg) produced an enhancement of 44 +/- 12% of the hepatic signal 5 min after intraportal injection in T1-weighted images. The potential applicability of the other nitroxyl lipids as contrast agents for MRI was limited in the in vivo studies by an unexpected toxicity. Work is currently in progress to improve the therapeutic index of the present class of nitroxyl lipids.

Animals↗
PubMed1988

Rapid and precise micro-methods for quantitating active components in commercial bone scintigraphy kits--II. Diphosphonates.

Two parallel, independent micro-methods for diphosphonate determination are presented. These procedures are based on the interference of diphosphonate with the formation of cation-morin (3,5,7,2',4'-pentahydroxyflavone) complexes. In the spectrophotometric method, a change of the absorbance of thorium-morin complex is used as a measure of diphosphonate concentration. In the fluorimetric method, a decrease of the fluorescence of aluminium-morin complex is used. Both methods: (1) quantitate methylene-diphosphonate in the range of 5-40 x 10(-9) M with a coefficient of variation of less than 1%; (2) are specific and interference-free in commercial kits control; (3) are operative with other diphosphonates; and (4) are adaptable to the analysis of chromatographic eluents.

Bone and Bones↗