STEROID FORMATION IN PORCINE OVARIAN TISSUE IN VITRO

1969 ◽  
Vol 60 (4) ◽  
pp. 621-634
Author(s):  
Asbjørn Aakvaag
Keyword(s):  
Ovarian Tissue ◽  
Isotope Ratios ◽  
The Other ◽  
Time Study ◽  
Sulphate Group ◽  
Tissue Slices ◽  
Specific Activities ◽  
Endogenous Substrates ◽  
Hydroxy Progesterone

ABSTRACT Ovarian tissue slices from the sow have been incubated simultaneously with pregnenolone and progesterone as substrates, one being labelled with 3H, the other with 14C. Progesterone, 17α-hydroxyprogesterone and androstenedione were isolated in a radiochemically pure form; the isotope ratios and the specific activities were determined after chemical quantitation by gas chromatography. Both substrates were used in the biosynthesis of the isolated compounds. The isotope ratios in progesterone, 17α-hydroxy-progesterone and androstenedione were identical or very similar, indicating that androstenedione was formed solely via the progesterone pathway. The results of a time study were in agreement with this conclusion. From the specific activities of the isolated steroids it appeared that the exogenous radioactivity and endogenous substrates were metabolized in a very similar manner. Pregnenolone sulphate was metabolized to the same isolated steroids. The first step in the conversion of this substrate appeared to be removal of the sulphate group.

STEROID FORMATION IN PORCINE OVARIAN TISSUE IN VITRO

1970 ◽  
Vol 63 (3) ◽  
pp. 441-453 ◽  
Author(s):  
Asbjørn Aakvaag
Keyword(s):  
Liquid Scintillation ◽  
Specific Activity ◽  
Ovarian Tissue ◽  
Gas Liquid Chromatography ◽  
Similar Concentration ◽  
Endogenous Substrates ◽  
Exogenous Progesterone ◽  
Relative Utilization ◽  
Radioactive Substrate

ABSTRACT Slices of non-luteinized porcine ovaries have been incubated in the presence or absence of human chorionic gonadotrophin (HCG) and exogenous radioactive substrates. Progesterone, 17α-hydroxyprogesterone and androstenedione were isolated in a radiochemically pure form. The chemical mass and the specific activity were determined by gas liquid chromatography and liquid scintillation spectrometry. HCG stimulated the rate of formation of androstenedione in the absence of exogenous substrates with a factor of 4–8. In the presence of pregnenolone or progesterone at a concentration of about 2 × 10−6 mol/l the stimulatory effect of HCG was either abolished or markedly reduced. The conversion of exogenous progesterone to androstenedione was reduced in response to HCG indicating that the capacity of the tissue to convert progesterone to androstenedione was limited, and that the limit was reached at this rather low substrate concentration. These findings furthermore suggest that the endogenous rather than the exogenous radioactive substrate will be »preferred« by the tissue. The observations demonstrate the necessity of measuring both the radioactivity and the chemical mass of the products in investigations of this type using radioactive substrates. The formation of progesterone from endogenous substrates was also stimulated by HCG. [1-14C] acetate and [7α-3H]cholesterol were not utilized by the tissue for steroid formation. Exogenous [4-14C] pregnenolone and [7α-3H] progesterone in similar concentration were both utilized for production of 17α-hydroxyprogesterone and androstenedione. HCG had no effect on the relative utilization of the radioactive substrates.

scholarly journals Polyprenyl Phosphate Biosynthesis inMycobacterium tuberculosis and Mycobacterium smegmatis

2000 ◽  
Vol 182 (20) ◽  
pp. 5771-5778 ◽  
Author(s):  
Dean C. Crick ◽  
Mark C. Schulbach ◽  
Erin E. Zink ◽  
Marco Macchia ◽  
Silvia Barontini ◽  
...  
Keyword(s):  
Mycobacterium Smegmatis ◽  
Farnesyl Diphosphate ◽  
The Other ◽  
Geranylgeranyl Diphosphate ◽  
Geranyl Diphosphate ◽  
Prenyl Diphosphate ◽  
Specific Activities ◽  
The Difference ◽  
Prenyl Diphosphate Synthase

ABSTRACT Mycobacterium smegmatis has been shown to contain two forms of polyprenyl phosphate (Pol-P), while Mycobacterium tuberculosis contains only one. Utilizing subcellular fractions from M. smegmatis and M. tuberculosis, we show that Pol-P synthesis is different in these species. The specific activities of the prenyl diphosphate synthases in M. tuberculosis are 10- to 100-fold lower than those in M. smegmatis. In M. smegmatis decaprenyl diphosphate and heptaprenyl diphosphate were the main products synthesized in vitro, whereas in M. tuberculosis only decaprenyl diphosphate was synthesized. The data from both organisms suggest that geranyl diphosphate is the allylic substrate for two distinct prenyl diphosphate synthases, one located in the cell membrane that synthesizes ω,E,Z-farnesyl diphosphate and the other present in the cytosol that synthesizes ω,E,E,E-geranylgeranyl diphosphate. In M. smegmatis, the ω,E,Z-farnesyl diphosphate is utilized by a membrane-associated prenyl diphosphate synthase activity to generate decaprenyl diphosphate, and the ω,E,E,E-geranylgeranyl diphosphate is utilized by a membrane-associated activity for the synthesis of the heptaprenyl diphosphate. In M. tuberculosis, however, ω,E,E,E-geranylgeranyl diphosphate is not utilized for the synthesis of heptaprenyl diphosphate. Thus, the difference in the compositions of the Pol-P ofM. smegmatis and M. tuberculosis can be attributed to distinct enzymatic differences between these two organisms.

Kit ligand promotes the transition from primordial to primary follicles afterin vitroculture of ovine ovarian tissue

Zygote ◽  
2015 ◽  
Vol 24 (4) ◽  
pp. 578-582 ◽  
Author(s):  
A.Y.P. Cavalcante ◽  
B.B. Gouveia ◽  
R.S. Barberino ◽  
T.L.B.G. Lins ◽  
L.P. Santos ◽  
...  
Keyword(s):  
Ovarian Tissue ◽  
The Other ◽  
Control Medium ◽  
Minimal Essential Medium ◽  
Preantral Follicles ◽  
Kit Ligand ◽  
Follicle Diameter

SummaryThis study evaluated the effects of kit ligand (KL) on the morphology and development of ovine preantral follicles (fresh control) and after 7 days ofin vitroculture in α-Minimal Essential Medium (α-MEM; control medium) or the presence of KL (1, 10, 50, 100 or 200 ng/ml). There was an increase in the percentage of primary follicles at the concentration of 100 ng/ml KL, compared with the fresh control, control medium (α-MEM) and the other KL concentrations. Follicle diameter was significantly higher than the control medium only at concentrations of 50 and 100 ng/ml KL. In conclusion, 100 ng/ml KL promoted the transition from primordial to primary follicles (follicular activation) afterin vitroculture of ovine ovarian tissue.

In Vitro Synthesis of Estrogen Glucuronides and Sulfates by Human Renal Tissue

1975 ◽  
Vol 53 (7) ◽  
pp. 779-783 ◽  
Author(s):  
Joyce D. Mellor ◽  
R. Hobkirk
Keyword(s):  
Renal Tissue ◽  
In Vivo Studies ◽  
Time Study ◽  
Tissue Slices ◽  
Experimental Conditions ◽  
In Vitro Synthesis ◽  
Estrone Sulfate ◽  
Layer Chromatography

17β-[6,7-3H]Estradiol (E2) was incubated with slices and homogenates of adult human renal tissue. The metabolites formed were identified by chromatography on DEAE-Sephadex, thin layer chromatography and crystallization with carrier steroids or steroid derivatives. The major metabolites formed by slices were estradiol-17-glucuronide (E217G), estrone sulfate and estradiol-3-sulfate. This is the first report of in vitro synthesis of estrogen sulfates by adult renal tissue. Minor quantities of the 3-glucuronides of estrone and estradiol were also found. An oxygen atmosphere appeared to stimulate the production of E217G. A time study with tissue slices showed similarities between the in vitro pattern of glucuronide synthesis and the excretion pattern of these compounds seen in earlier in vivo studies. Homogenates fortified with uridine diphosphoglucuronic acid formed the same pattern of glucuronide products but in lesser amounts. No sulfates were formed under these conditions. Testosterone did not act as a substrate in the experimental conditions used.

PATHWAYS IN THE BIOSYNTHESIS OF ANDROSTENEDIONE IN THE HUMAN OVARY IN VITRO

1969 ◽  
Vol 60 (3) ◽  
pp. 517-526 ◽  
Author(s):  
Asbjørn Aakvaag
Keyword(s):  
Normal Tissue ◽  
Ovarian Tissue ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
The Other ◽  
Human Ovary ◽  
Progesterone Concentration ◽  
Human Ovarian Tissue ◽  
Relative Utilization

ABSTRACT Human ovarian tissue was incubated with pregnenolone and progesterone simultaneously, one labelled with 3H, the other with 14C. Isolation and quantitation of metabolites indicated that the preferred pathway to androstenedione from pregnenolone was through the Δ5-intermediates, in normal tissue, as well as in tissue from a patient with the Stein-Leventhal's syndrome. Metabolism of pregnenolone was essentially unaffected by the progesterone concentration in the medium. Addition of human chorionic gonadotrophin to the medium did not influence the relative utilization of the two substrates for biosynthesis of androstenedione.

KINETIC STUDIES ON THE ENZYMES CATALYSING THE CONVERSION OF 17α-HYDROXY-PROGESTERONE AND DEHYDROEPIANDROSTERONE TO ANDROSTENEDIONE IN THE HUMAN ADRENAL GLAND IN VITRO

1974 ◽  
Vol 60 (1) ◽  
pp. 27-35 ◽  
Author(s):  
JEAN YATES ◽  
N. DESHPANDE
Keyword(s):  
Adrenal Gland ◽  
Kinetic Study ◽  
Microsomal Fraction ◽  
Kinetic Studies ◽  
The Other ◽  
Side Chain ◽  
Adrenal Cell ◽  
Chain Cleavage ◽  
Hydroxy Progesterone

SUMMARY Factors controlling the synthesis of androstenedione in the human adrenal gland were investigated in a kinetic study of the enzymes catalysing the conversion of 17α-hydroxyprogesterone and dehydroepiandrosterone to the hormone. Both reactions are associated with the microsomal fraction of the adrenal cell. 17α-Hydroxyprogesterone is converted to androstenedione by a NADPH-dependent 17-desmolase whereas there is an obligatory requirement for NAD+ for the conversion of dehydroepiandrosterone to the hormone. None of the other cofactors investigated inhibited or enhanced the enzymic conversions. The side-chain cleavage of 17α-hydroxyprogesterone was competitively inhibited by the precursors of the substrate, pregnenolone, progesterone and 17α-hydroxypregnenolone. Other C19 or C18 compounds known to be synthesized by the human adrenal gland were found to be ineffective in modifying the enzyme action. The conversion of dehydroepiandrosterone to androstenedione was non-competitively inhibited by oestrone and oestradiol-17β. No C21 compounds were found to affect the reaction. 5α-Dihydrotestosterone (17β-hydroxy-5α-androstan-3-one) inhibited both enzymic conversions competitively but the inhibition constants observed were so high that it is unlikely that this finding has any relevance to the control of androstenedione synthesis in vitro.

A new in vitro model for pre-transplantation diagnosis of frozen/thawed human ovarian tissue

2011 ◽  
Vol 71 (05) ◽  
Author(s):  
M Salama ◽  
K Winkler ◽  
KF Murach ◽  
S Hofer ◽  
L Wildt ◽  
...  
Keyword(s):  
In Vitro Model ◽  
Ovarian Tissue ◽  
Human Ovarian Tissue ◽  
Vitro Model

Enhancement of ADP-induced Platelet Aggregation by Adrenaline in Vivo and Its Prevention

1973 ◽  
Vol 29 (02) ◽  
pp. 490-498 ◽  
Author(s):  
Hiroh Yamazaki ◽  
Itsuro Kobayashi ◽  
Tadahiro Sano ◽  
Takio Shimamoto
Keyword(s):  
Platelet Count ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
The Other ◽  
Endothelial Surface ◽  
Important Interaction ◽  
Blood Coagulability ◽  
The Difference

SummaryThe authors previously reported a transient decrease in adhesive platelet count and an enhancement of blood coagulability after administration of a small amount of adrenaline (0.1-1 µg per Kg, i. v.) in man and rabbit. In such circumstances, the sensitivity of platelets to aggregation induced by ADP was studied by an optical density method. Five minutes after i. v. injection of 1 µg per Kg of adrenaline in 10 rabbits, intensity of platelet aggregation increased to 115.1 ± 4.9% (mean ± S. E.) by 10∼5 molar, 121.8 ± 7.8% by 3 × 10-6 molar and 129.4 ± 12.8% of the value before the injection by 10”6 molar ADP. The difference was statistically significant (P<0.01-0.05). The above change was not observed in each group of rabbits injected with saline, 1 µg per Kg of 1-noradrenaline or 0.1 and 10 µg per Kg of adrenaline. Also, it was prevented by oral administration of 10 mg per Kg of phenoxybenzamine or propranolol or aspirin or pyridinolcarbamate 3 hours before the challenge. On the other hand, the enhancement of ADP-induced platelet aggregation was not observed in vitro, when 10-5 or 3 × 10-6 molar and 129.4 ± 12.8% of the value before 10∼6 molar ADP was added to citrated platelet rich plasma (CPRP) of rabbit after incubation at 37°C for 30 second with 0.01, 0.1, 1, 10 or 100 µg per ml of adrenaline or noradrenaline. These results suggest an important interaction between endothelial surface and platelets in connection with the enhancement of ADP-induced platelet aggregation by adrenaline in vivo.

ALDOSTERONE STIMULATION IN VITRO

1965 ◽  
Vol 50 (2) ◽  
pp. 301-309 ◽  
Author(s):  
Jürg Müller
Keyword(s):  
Ammonium Chloride ◽  
Human Urine ◽  
Incubation Medium ◽  
The Other ◽  
Ammonium Ions ◽  
Response Curves ◽  
Urine Extract ◽  
Similar Dose ◽  
Aldosterone Production

ABSTRACT An extract of human urine, which was previously shown to stimulate aldosterone production by rat adrenal sections, was further purified. Evidence was obtained that its aldosterone-stimulating effect was due to the presence of ammonium ions. Addition of ammonium chloride and of urine extract to the incubation medium caused identical increases in aldosterone production in vitro. In addition to ammonium ions, rubidium and caesium ions also stimulated aldosterone production up to 250% that of control values without a significant effect on corticosterone production. Similar dose-response curves were obtained when increasing concentrations of potassium, ammonium, rubidium and caesium ions were tested. Aldosterone production was maximal at concentrations of 7 mval/1 and was significantly lower at higher concentrations. When ammonium chloride and ACTH were simultaneously added to the incubation medium, the production of aldosterone and of corticosterone was lower than with ACTH alone. On the other hand, the stimulating activity on aldosterone and corticosterone production by »TPN« (NADP) and glucose-6-phosphate was enhanced by the simultaneous addition of ammonium chloride.

EFFECT OF ACTINOMYCIN D ON TSH-INDUCED STIMULATION OF THYROIDAL PROTEIN SYNTHESIS IN THE RAT

1974 ◽  
Vol 77 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Gustav Wägar
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
The Other ◽  
Leucine Incorporation ◽  
Short Term ◽  
Other Hand ◽  
Thyroid Glands ◽  
Translational Level ◽  
Stimulation Of

ABSTRACT Whether the short-term regulation of thyroidal protein synthesis by TSH occurs at the transcriptional or the translational level was tested by measuring the effect of actinomycin D (act D) on the TSH-induced stimulation of L-14C-leucine incorporation into the thyroidal proteins of rats. TSH was injected 6 h before the rats were killed. The thyroid glands were then removed and incubated in vitro in the presence of L-14C-leucine for 2 h. The pronounced stimulation of leucine incorporation in the TSH-treated animals was depressed as compared with controls but still significant even when the animals had been pre-treated with 100 μg act D 24 and 7 h before sacrifice. On the other hand, act D strongly decreased incorporation of 3H-uridine into RNA. Short-term regulation of thyroidal protein synthesis by TSH appears to be partly but not wholly dependent on neosynthesis of RNA. Hence regulation may partly occur at the translation level of protein synthesis.

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