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See detailGenetic regulation of hepatic steroid 16 alpha-hydroxylase activities in inbred strains of mice.
Pasleau, Françoise ULg; Kolodzici, Claudine; Kremers, Pierre ULg et al

in Endocrinology (1984), 115

Steroid 16 alpha-hydroxylase activities and properties were studied in C57Bl/6J, 129/J, AKR/R, DBA/2J, C3H/I, and BALB/c mouse liver using four different substrates. The highest enzymatic activities were ... [more ▼]

Steroid 16 alpha-hydroxylase activities and properties were studied in C57Bl/6J, 129/J, AKR/R, DBA/2J, C3H/I, and BALB/c mouse liver using four different substrates. The highest enzymatic activities were measured in the female mice, with the exception of the 129/J females. As in the rat liver, the sexual differentiation of the steroid 16 alpha-hydroxylation observed in adult male and female mice took place at puberty. In the adult mouse liver, two steroid 16 alpha-hydroxylase activities (forms I and II) could be differentiated on the basis of their relative affinities for the various steroid substrates and their relative proportions in male and female mouse livers. In the immature mouse liver, no sexual differences could be detected, and the mice of both sexes presented phenotypes identical to those of the adult female. The adult 129/J females appeared genetically deficient with respect to the form I of the steroid 16 alpha-hydroxylase and presented a phenotype identical to that of the adult male mice of the various strains tested. Differences in hydroxylase activities between the C57Bl/6J and 129/J strains were investigated using standard genetic breeding protocols. Steroid 16 alpha-hydroxylase seemed to be inherited additively in the liver of the female mice obtained by crossing the C57Bl/6J male and the 129/J female or the 129/J male and the C57Bl/6J female. In the male mice, regardless of genotype, the observed phenotype was always identical to the two male parental types. Both hormonal and genetic regulations were responsible for the different phenotypes occurring in adult male and female C57Bl/6J and 129/J mouse livers. [less ▲]

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See detailGenetic regulation of hepatic steroid 16alpha-hydroxylase activities in inbred strains of mice.
Pasleau, Françoise ULg; Kolodzici, Claudine; Kremers, Pierre ULg et al

Poster (1982, September)

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See detailOntogenic development of steroid 16 alpha-hydroxylase as a tool for the study of the multiplicity of cytochrome P-450.
Pasleau, Françoise ULg; Kolodzici, Claudine; Kremers, Pierre ULg et al

in European Journal of Biochemistry (1981), 120

1. Activities of progesterone, testosterone, pregnenolone and dehydroepiandrosterone 16 alpha-hydroxylase are undetectable in the fetal rat liver. During the neonatal period, the four enzymic activities ... [more ▼]

1. Activities of progesterone, testosterone, pregnenolone and dehydroepiandrosterone 16 alpha-hydroxylase are undetectable in the fetal rat liver. During the neonatal period, the four enzymic activities increase in parallel to the concentration of cytochrome P-450. Until puberty, they develop similarly in male and female rat livers. From the 40th to the 55th day, the four steroid 16 alpha-hydroxylase activities increase rapidly in the male rat liver. The sexual differentiation of the steroid 16 alpha-hydroxylation observed in adult male and female rats takes place around the 55th day. 2. In the adult rat liver, steroid 16 alpha-hydroxylase is supported by two forms of cytochrome P-450 (form I and form II), which differ in their relative affinities for the various steroid substrates, and by their relative proportions in male and female rat livers. These two forms of cytochrome P-450 are also present in the young male and female rat livers, but are roughly equal in proportion. The transition from the immature to the adult repartition of the two forms occurs during puberty and is correlated with the sexual differentiation of the steroid 16 alpha-hydroxylase activities. 3. During the critical phases of the rat ontogenic development, the in vitro interactions between benzo[a]pyrene and steroids were compared at the level of two rat liver monooxygenases: steroid 16 alpha-hydroxylase and aryl hydrocarbon hydroxylase. (a) In the immature male and female rat livers, progesterone 16 alpha-hydroxylase, and to a lesser extent, pregnenolone 16 alpha-hydroxylase are inhibited by benzo[a]pyrene. Progesterone 16 alpha-hydroxylase is also inhibited by metyrapone. (b) In the young rat, aryl hydrocarbon hydroxylase cannot be inhibited by steroids and appears to be supported by a single form of cytochrome P-450. The transition from the immature to the adult situation occurs around the 40th day. [less ▲]

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See detailCompetition between benzo[a]pyrene and various steroids for cytochrome P-450-dependent rat liver monooxygenases.
Pasleau, Françoise ULg; Kremers, Pierre ULg; Gielen, Jacques

in Chemico-Biological Interactions (1981), 34

Cytochrome P-450-dependent monooxygenases are able to oxidize a large variety of endogenous and exogenous substrates. This paper describes the in vitro interaction between benzopyrene and steroids at the ... [more ▼]

Cytochrome P-450-dependent monooxygenases are able to oxidize a large variety of endogenous and exogenous substrates. This paper describes the in vitro interaction between benzopyrene and steroids at the level of two rat liver monooxygenases: steroid-16 alpha-hydroxylase and aryl hydrocarbon hydroxylase (AHH). The results obtained suggest the following conclusions: (1) Steroid-16 alpha-hydroxylase is partially supported by a specific cytochrome P-450 form which is not inhibited in vitro by exogenous substrates. Steroid-16 alpha-hydroxylase is completely independent from cytochrome P1-450 (or P-448), as it is insensitive, in vitro, to alpha-naphthoflavone; (2) AHH is supported by two cytochrome P-450 forms: a specific form which is inducible by methylcholanthrene and inhibited in vitro by alpha-naphthoflavone, but is insensitive to metyrapone and steroids; and another less specific form which is inhibited by metyrapone and steroids in vitro. [less ▲]

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See detailSex differences in the activity of different cytochrome P450 dependent steroid 16alpha-hydroxylases in rat liver
Pasleau, Françoise ULg; Kremers, Pierre ULg; Gielen, Jacques

in Journal of Steroid Biochemistry & Molecular Biology (1980), 13

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See detailBiochemical and biological properties of steroid 16alpha-hydroxylase.
Gielen, Jacques; Cantineau, Robert; Degraeve, Jacques et al

Conference (1980, March)

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See detailSteroid 16alpha-hydroxylase multiplicity in rat liver.
Gielen, Jacques; Kremers, Pierre ULg; Pasleau, Françoise ULg

in Biochemistry, Biophysics and Regulation of Cytochrome. (1980)

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See detailRégulation de l’activité des monooxygénases microsomales au cours de la croissance.
Gielen, Jacques; Kremers, Pierre ULg; Pasleau, Françoise ULg

in Les Colloques de l'INSERM, Pharmacologie du Développement (1979)

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See detailIs steroid 16alpha-hydroxylase supported by more than one mono-oxygenase.
Kremers, Pierre ULg; Pasleau, Françoise ULg; Gielen, Jacques

in Biochemical and Biophysical Research Communications (1978)

Steroid-16α-hydroxylase activities have been measured in normal and induced rat livers using four different substrates. The male/female activity ratio as well as the induction factor vary with the ... [more ▼]

Steroid-16α-hydroxylase activities have been measured in normal and induced rat livers using four different substrates. The male/female activity ratio as well as the induction factor vary with the substrate indicating that steroid-16α-hydroxylase activity is a heterogenous enzyme. Experiments using specific inhibitors led to the conclusion that steroid-16α-hydroxylase is supported by at least two cytochrome P-450 forms, different from the cytochrome P-448. [less ▲]

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See detailMultiplicity of cytochrome P450 dependent steroid 16alpha-hydroxylase in the rat liver.
Kremers, Pierre ULg; Pasleau, Françoise ULg; Gielen, Jacques

Conference (1978, June)

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