FORMATION OF 17α-HYDROXY-PREGNENOLONE, 17α-HYDROXY-PROGESTERONE AND PROGESTERONE BY HYDATIDIFORM MOLES IN VITRO

1969 ◽  
Vol 61 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Hubertus A. van Leusden ◽  
Maria Siemerink
Keyword(s):  
Urinary Excretion ◽  
Specific Activity ◽  
Full Term ◽  
Hydroxy Progesterone ◽  
Experimental Findings ◽  
Hydatidiform Moles ◽  
Constant Specific Activity

ABSTRACT Vesicles of hydatidiform moles were incubated in the presence of [7α-3H]pregnenolone, After the incubation and extraction of tissues and media, 17α-hydroxy-pregnenolone*, 17α-hydroxy-progesterone and progesterone were identified using a number of TLC systems, followed by crystallization to a constant specific activity. [7α-3H] pregnenolone was not converted to oestrone, 17β-oestradiol and oestriol. The experimental findings indicate that hydatidiform moles, like full term placentas, are deficient in the enzymes necessary to convert C21 to C19 steroids. The production of 17α-hydroxy-progesterone and progesterone in the molar trophoblast in situ may contribute to the considerable urinary excretion of pregnanetriol and pregnanediol in patients with hydatidiform moles.

CONVERSION OF ANDROGENS INTO OESTROGENS BY HYDATIDIFORM MOLES IN VITRO

1970 ◽  
Vol 64 (1) ◽  
pp. 17-37 ◽  
Author(s):  
Hans L. Houtzager ◽  
Hubertus A. van Leusden ◽  
Maria Siemerink
Keyword(s):  
Specific Activity ◽  
Hydatidiform Mole ◽  
No Conversion ◽  
Direct Pathway ◽  
Endogenous Production ◽  
Hydatidiform Moles ◽  
Constant Specific Activity

ABSTRACT [1,2-3H] and [7α-3H] testosterone* and [4-14C] androstenedione incubated with hydatidiform mole tissue are converted into oestrone and oestradiol. No conversion into oestriol was observed. The radiometabolites were purified using TLC in different systems and crystallization to a constant specific activity and/or 14C/3H ratio. Appropriate corrections were made for endogenous production of steroids during the incubation. From time-experiments with [4-14C] androstenedione and [7α-3H] or [1,2-3H] testosterone it appears, that androstenedione is a more effective precursor than testosterone for oestrone and oestradiol. Equilibrium oestrone ⇋ oestradiol is established more rapidly than androstenedione ⇋ testosterone. Conversion of androstenedione into oestrone is more effective than conversion of testosterone into androstenedione. Data are reported in agreement with the hypothesis of a direct pathway from testosterone to oestradiol in the shorter periods of incubation. Determination of the endogenous pools of oestrone, oestradiol, testosterone and androstenedione synthesized during the incubations indicates that oestrone is the most important steroid produced in vitro.

Expression of a novel FGF in the Xenopus embryo. A new candidate inducing factor for mesoderm formation and anteroposterior specification

Development ◽  
1992 ◽  
Vol 114 (3) ◽  
pp. 711-720 ◽  
Author(s):  
H.V. Isaacs ◽  
D. Tannahill ◽  
J.M. Slack
Keyword(s):  
Specific Activity ◽  
Biological Properties ◽  
The Body ◽  
Mesoderm Induction ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Mesoderm Formation ◽  
Low Levels

We have cloned and sequenced a new member of the fibroblast growth factor family from Xenopus laevis embryo cDNA. It is most closely related to both mammalian kFGF (FGF-4) and FGF-6 but as it is not clear whether it is a true homologue of either of these genes we provisionally refer to it as XeFGF (Xenopus embryonic FGF). Two sequences were obtained, differing by 11% in derived amino acid sequence, which probably represent pseudotetraploid variants. Both the sequence and the behaviour of in vitro translated protein indicates that, unlike bFGF (FGF-2), XeFGF is a secreted molecule. Recombinant XeFGF protein has mesoderm-inducing activity with a specific activity similar to bFGF. XeFGF mRNA is expressed maternally and zygotically with a peak during the gastrula stage. Both probe protection and in situ hybridization showed that the zygotic expression is concentrated in the posterior of the body axis and later in the tailbud. Later domains of expression were found near the midbrain/hindbrain boundary and at low levels in the myotomes. Because of its biological properties and expression pattern, XeFGF is a good candidate for an inducing factor with possible roles both in mesoderm induction at the blastula stage and in the formation of the anteroposterior axis at the gastrula stage.

GLUCOCORTICOID SYNTHESIS FROM PREGNENOLONE BY SHEEP FOETAL ADRENALS IN VITRO

1973 ◽  
Vol 58 (3) ◽  
pp. 485-491 ◽  
Author(s):  
I. J. DAVIES ◽  
K. J. RYAN
Keyword(s):  
Isotope Dilution ◽  
Adrenal Glands ◽  
Specific Activity ◽  
Newborn Period ◽  
Adult Sheep ◽  
Age Related ◽  
Period Of Gestation ◽  
Constant Specific Activity

SUMMARY [7-3H]Pregnenolone was incubated with homogenates of adrenal glands from two 100-day-old sheep foetuses. Cortisol and corticosterone were isolated and identified by reverse isotope dilution and recrystallization to constant specific activity. Together these two compounds accounted for 12% and 17% of the substrate with the two tissue preparations. Other C21 and C19 metabolites which were sought were not present in appreciable quantities. Additional incubations were done with the adrenals of lamb foetuses ranging in age from 110 days of gestation to the immediate newborn period. Glucocorticoidogenic capacity similar to that of the 100-day-old foetuses was demonstrated throughout this period and no age-related change was evident. These results demonstrate that the lamb foetal adrenal has a substantial enzymic capacity for glucocorticoid synthesis throughout at least the last third of gestation. In conjunction with the observations of others, these experiments support the hypothesis that during this period of gestation the lamb foetal adrenal is actively synthesizing glucocorticoids in a manner which is similar to the lamb at term and the adult sheep.

THE CONVERSION OF PROGESTERONE TO 17α-HYDROXYPROGESTERONE BY HUMAN PLACENTA IN VITRO

1961 ◽  
Vol 36 (3) ◽  
pp. 455-461 ◽  
Author(s):  
Brian Little ◽  
Ann Shaw
Keyword(s):  
Human Placenta ◽  
Radiochemical Purity ◽  
Specific Activity ◽  
Fluid Fraction ◽  
Counter Current ◽  
Soluble Supernatant ◽  
Counter Current Distribution ◽  
Generating System ◽  
Constant Specific Activity

ABSTRACT The conversion of progesterone to 17α-hydroxyprogesterone by the soluble fraction of human placenta has been demonstrated in vitro. The incubation system contained the soluble supernatant fluid fraction of placental homogenate (105 000 × g), progesterone 4-14C as substrate, authentic 17α-hydroxyprogesterone as trap and a reduced triphosphopyridine nucleotide generating system as cofactor. The 17α-hydroxyprogesterone formed was isolated chromatographically and radiochemical purity was demonstrated by constant specific activity in a counter current distribution. Constant specific activity and radiochemical purity of the oxidation product and the acetylated derivative was also shown.

THE CONVERSION OF PREGNENOLONE TO PROGESTERONE AND 16α-HYDROXYDEHYDROEPIANDROSTERONE IN VITRO BY ADRENAL TISSUE FROM A NEWBORN ANENCEPHALIC INFANT

1968 ◽  
Vol 40 (1) ◽  
pp. 29-35 ◽  
Author(s):  
M. M. SHAHWAN ◽  
R. E. OAKEY ◽  
S. R. STITCH
Keyword(s):  
Specific Activity ◽  
Hydroxysteroid Dehydrogenase ◽  
Enzymatic Conversion ◽  
Partition Chromatography ◽  
Adrenal Tissue ◽  
Enzyme Systems ◽  
Constant Specific Activity

SUMMARY Adrenal tissue, largely composed of the definitive zone, from a newborn anencephalic infant, contained the following enzyme systems: (1) a Δ5-3β-hydroxysteroid dehydrogenase for pregnenolone, demonstrated by the conversion of [14C]pregnenolone to [14C]progesterone; (2) a C(17)-C(20) desmolase, and (3) a steroid 16α-hydroxylase, demonstrated by the conversion of [14C]pregnenolone to [14C]3β, 16α-dihydroxyandrost-5-en-17-one. The metabolites could not be separated from carrier steroids during sequential partition chromatography. [14C]Progesterone was identified by recrystallization to constant specific activity. [14C]3β, 16α-Dihydroxyandrost-5-en-17-one was identified by enzymatic conversion to [14C]16α-hydroxyoestrone followed by reduction to oestriol and determination of the specific activity of the oestriol after partition chromatography. It is suggested that these enzymes may play some part in the production of cortisol by the newborn anencephalic infant, and in the provision of precursors for placental oestriol production.

scholarly journals Relative Expression Levels Rather Than Specific Activity Plays the Major Role in Determining In Vivo AKT Isoform Substrate Specificity

2011 ◽  
Vol 2011 ◽  
pp. 1-18 ◽  
Author(s):  
Rachel S. Lee ◽  
Colin M. House ◽  
Briony E. Cristiano ◽  
Ross D. Hannan ◽  
Richard B. Pearson ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Specific Activity ◽  
Dominant Role ◽  
Protein Substrates ◽  
Cellular Processes ◽  
Disease States ◽  
The Individual

The AKT protooncogene mediates many cellular processes involved in normal development and disease states such as cancer. The three structurally similar isoforms: AKT1, AKT2, and AKT3 exhibit both functional redundancy and isoform-specific functions; however the basis for their differential signalling remains unclear. Here we show that in vitro, purified AKT3 is ∼47-fold more active than AKT1 at phosphorylating peptide and protein substrates. Despite these marked variations in specific activity between the individual isoforms, a comprehensive analysis of phosphorylation of validated AKT substrates indicated only subtle differences in signalling via individual isoforms in vivo. Therefore, we hypothesise, at least in this model system, that relative tissue/cellular abundance, rather than specific activity, plays the dominant role in determining AKT substrate specificity in situ.

scholarly journals Micronuclei and the cytoplasm of growing Tetrahymena contain a histone acetylase activity which is highly specific for free histone H4.

1988 ◽  
Vol 106 (4) ◽  
pp. 1017-1026 ◽  
Author(s):  
R Richman ◽  
L G Chicoine ◽  
M P Collini ◽  
R G Cook ◽  
C D Allis
Keyword(s):  
Thermal Inactivation ◽  
Specific Activity ◽  
Enzyme Assays ◽  
Histone H4 ◽  
Core Histones ◽  
Cytosolic Extract ◽  
Histone Acetyltransferase Activity

Salt extracts prepared from purified micronuclei and the cytoplasm of growing Tetrahymena contain a histone acetylase (also referred to as histone acetyltransferase) activity which is highly specific for H4 when tested as a free histone. With both extracts, H4 is acetylated first at position 4 (monoacetylated) or positions 4 and 11 (diacetylated), sites diagnostic of deposition-related acetylation of newly synthesized H4 in vivo. As the concentration of cytosolic extract is decreased in the in vitro reactions, acetylation of H3 is also observed. Neither activity acetylates histone in a chromatin form. These activities are distinct from a macronuclear acetylase which acetylates H3 and H4 (macro- or micronuclear) equally well as free histones and which acetylates all four core histones when mononucleosomes are used as substrate. As well, the micronuclear and cytoplasmic activities give similar thermal-inactivation profiles which are different from that of the macronuclear activity. In situ enzyme assays demonstrate a macronuclear-specific activity which acetylates endogenous macronuclear chromatin and an independent micronuclear-cytosolic activity which is able to act upon exogenously added free H4. These results argue strongly that an identical acetylase is responsible for the micronuclear and cytoplasmic activity which is either modified or altogether distinct from that in macronuclei.

CORTICOSTEROID SYNTHESIS IN VITRO BY ADRENAL TISSUE FROM NEWBORN ANENCEPHALIC INFANTS

1969 ◽  
Vol 44 (4) ◽  
pp. 557-566 ◽  
Author(s):  
M. M. SHAHWAN ◽  
R. E. OAKEY ◽  
S. R. STITCH
Keyword(s):  
Newborn Infant ◽  
Specific Activity ◽  
Adrenal Tissue ◽  
Constant Specific Activity

SUMMARY Adrenal tissue from newborn anencephalic infants converted pregnenolone and progesterone to cortisol, 17α-hydroxyprogesterone, corticosterone, 17α,21-dihydroxyprogesterone, deoxycorticosterone and 1 1β-hydroxyprogesterone in vitro. These metabolites were identified by recrystallization to constant specific activity after multiple chromatography and derivative formation. The results demonstrate a potential for corticosteroid biosynthesis, at least from pregnenolone and progesterone, by the adrenals of the anencephalic infant, and therefore possibly by the definitive zone of the adrenal of the normal newborn infant.

METABOLISME DE LA TESTOSTERONE PAR LES CANAUX DE WOLFF DE L'EMBRYON DE RAT

1972 ◽  
Vol 70 (2) ◽  
pp. 351-359
Author(s):  
J.-P. Weniger ◽  
A. Zeis
Keyword(s):  
Specific Activity ◽  
Wolffian Duct ◽  
Rat Embryos ◽  
Duct Development ◽  
Constant Specific Activity

ABSTRACT Wolffian ducts from 17½-day-old rat embryos were cultivated in vitro in the presence of [4-14C] testosterone. The most important metabolite, if not the single one, was dihydrotestosterone, which was identified by recrystallization to constant specific activity. The discussion turns on the role dihydrotestosterone may play in normal Wolffian duct development. In parallel studies, testosterone was found to be converted into dihydrotestosterone, androsterone, androstanedione and 5α-androstan-3α,17β-diol by the kidney. Androsterone and androstanedione were metabolites of testosterone in the liver.

Stimulation of aromatase activity in the fetal rat gonads by cAMP and FSH

1988 ◽  
Vol 119 (3) ◽  
pp. 381-385 ◽  
Author(s):  
J.-P. Weniger ◽  
A. Zeis
Keyword(s):  
Specific Activity ◽  
Isotopic Dilution ◽  
Aromatase Activity ◽  
Fetal Rat ◽  
Estrogen Synthesis ◽  
Fetal Rats ◽  
Stimulation Of ◽  
Constant Specific Activity

Abstract. The gonads from 17- to 21-day-old fetal rats were cultured in vitro in the presence of [3H]testosterone and in the presence or absence of cAMP or FSH, and estrone and estradiol formed were measured by double isotopic dilution and recrystallization to constant specific activity. Estrogen synthesis by testes was stimulated by both cAMP and FSH as early as at 18 days of gestation. FSH did not enhance aromatase activity in ovaries, although cAMP did. It is remarkable that FSH controls estrogen synthesis in the testis earlier than in the ovary.

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