Nicole Autissier

Action du manganese methylcyclopentadienyle tricarbonyle (MMT) sur les mitochondries I. Effects du MMT, in vitro, sur la phosphorylation oxydative des mitochondries hepatiques de rats

Abstract Effects of methylcyclopentadienyl manganese tricarbonyl (MMT) of rat liver mitochondria. I. Effects, in vitro, on the oxidative phosphorylation . Methylcyclopentadienyl manganese tricarbonyl (MMT) is an effective inhibitor of mitochondrial respiration associated with NAD + -linked substrates. At concentrations which inhibit glutamate-malate oxidation (over 80% inhibition) succinate and tetramethylphenylenediamine (TMPD)-ascorbate are inhibited less than 25%. MMT inhibits both electron and energy transfer in mitochondria as revealed by the partial release of MMT inhibition by 2,4-dinitrophenol (DNP). The data indicated that the effects of MMT are supported by energy conservation at site I of the respiratory chain.

Specificite de L'Iodotyrosine desiodase des microsomes thyroïdiens et hepatiques

Abstract The deiodinating activity of thyroid and liver microsomes was studied with 19 compounds including 3-iodo- l -tyrosine and 3:5-diiodo- l -tyrosine and their analogs. While l -iodotyrosines were almost completely dehalogenated, d -iodotyrosines, α-methyl- dl -iodotyrosines and 3:5-diiodo-4-hydroxyphenyl- dl -lactic acid were poor substrates for the deiodinase. All the other compounds tested remained unchanged including 3:5-diiodo-4-hydroxyphenyl-α guanidyl propionic acid, 3:5-diiodo-4-hydroxyphenyl propionic acid and 3:5-diiodotyramine. The phenol group played a major role since 3-iodo-5-nitro- l -tyrosine and 3-iodo- l -phenylalanine were not decomposed. In conclusion, thyroid and liver deiodinase are highly specific enzymes. It appears probable that the enzymatic site requires the carboxyl, amino and phenol groups of the substrate to exert its activity.Abstract The deiodinating activity of thyroid and liver microsomes was studied with 19 compounds including 3-iodo- l -tyrosine and 3:5-diiodo- l -tyrosine and their analogs. While l -iodotyrosines were almost completely dehalogenated, d -iodotyrosines, α-methyl- dl -iodotyrosines and 3:5-diiodo-4-hydroxyphenyl- dl -lactic acid were poor substrates for the deiodinase. All the other compounds tested remained unchanged including 3:5-diiodo-4-hydroxyphenyl-α guanidyl propionic acid, 3:5-diiodo-4-hydroxyphenyl propionic acid and 3:5-diiodotyramine. The phenol group played a major role since 3-iodo-5-nitro- l -tyrosine and 3-iodo- l -phenylalanine were not decomposed. In conclusion, thyroid and liver deiodinase are highly specific enzymes. It appears probable that the enzymatic site requires the carboxyl, amino and phenol groups of the substrate to exert its activity.

Synthesis et activites biologiques de certains derives thyroxiniens et adrenergiques—VII Influence de divers derives phenoliques iodes sur la monoamine oxydase hepatique de cobaye et sur la monoamine oxydase cerebrale de rat

The action on hepatic and cerebral monoamine oxidase of several iodinated phenols derivated from 3:5-diiodotyramine and thyroid hormones and some of their structural analogues was studied. The enzymatic activity was tested by a variety of methods and in addition a new technique was developed using polarographic measurement of dissolved oxygen. Iproniazid was used as standard inhibitor. 3:5-Diiodotyramine is a potent inhibitor of guinea-pig liver MAO but no effect was obtained on rat cerebral MAO. Iodothyroacetic acids [3:5-diiodothyroacetic acid (TA2) and 3:5:3′-triiodothyroacetic acid (TA3)] and 3:5-diidothyroadrenaline- (TAd2) were inhibitors of both liver and cerebral MAO. L-thyroxine (T4) and 3:5:3′-triiodo-L-thyronine (T3) no activity on liver MAO, whereas triiodothyronine has a relative effect on the cerebral enzyme.

Measurement of thyroid hormone in the rat thyroid gland by radioimmunoassay

The present paper describes (i) a hydrolysis technique with Pronase and leucine aminopeptidase using one rat thyroid gland, resulting in maximum release of thyroid hormones and minimum deiodination, and (ii) a simple and rapid procedure for thyroid hormone radioimmunoassays in thyroid hydrolysates using commercial kits intended for serum thyroid hormone determinations. The procedure is used to determine T4, T3, and rT3 concentrations and hormonal molar ratios in a thyroid gland from a male Wistar rat. The reliability of the method is also studied.

Action du manganese methylcyclopentadienyle tricarbonyle (MMT) sur les mitochondries II. Relation activite-structure

Resume Effects of methylcyclopentadienyl manganese tricarbonyl (MMT) on rat liver mitochondria. II. Activity-structure relation The action of various manganese organic compounds, which are structural analogs of methylcyclopentadienyl manganese tricarbonyl (MMT), was investigated. Only the cyclopentadienyl manganese tricarbonyl compounds are effective inhibitors of mitochondrial respiration, but only when associated with NAD+-linked substrates. The manganese tricarbonyl group is required for this mitochondrial respiration inhibition. The substitutions operated on the cyclopentadienyl cycle also interfere and increase the inhibitory effect. Meanwhile, the benzoyl and thenoyl groups are more effective than the methyl group. The effects of the various compounds result from their special electronic configuration.