scholarly journals Uptake and Metabolism of Tritiated 17ß-Oestradiol and Oestrone by Rabbit Uterine Tissue in vitro

1974 ◽  
Vol 27 (2) ◽  
pp. 137 ◽  
Author(s):  
RG Gabb ◽  
GM Stone
Keyword(s):  
Nuclear Receptor ◽  
Mode Of Action ◽  
Nuclear Extract ◽  
Lower Proportion ◽  
The Other ◽  
Uterine Tissue ◽  
Uptake And Metabolism

To determine whether the established capability of rabbit uterine tissue to interconvert 17 p-oestradiol and oestrone might have some effect on the mode of action of the oestrogens in this organ, the in vitro interconversion of [3H]-17p-oestradiol and [3H]oestrone by rabbit endometrial and myometrial tissue was investigated and the identity of radiometabolites in 'soluble, 'mitochondrial-microsomal' a'nd 'nuclear' preparations was studied. Both endometrial and myometrial tissue were found to be capable of oxidoreduction of the oestrogens, the equilibrium of the reaction favouring the reduction of oestrone. Irrespective of the tissue--steroid combination studied, the greater part of the radioactivity in all fractions was associated with 17p-oestradiol. The relative proportions of [3Hl-17p-oestradiol and [3H]oestrone varied between fractions, the nuclear preparation consistently showing a lower proportion of oestrone than the other fractions. Sephade<c fractionation of a 0'4M KCl 'nuclear extract' revealed that proportionately less oestrone than 17p-oestradiol was bound to the nuclear 'receptor'. These findings provide further evidence for 17p-oestradiol being the ovarian oestrogen which is active in the uterus, and suggest a role for uterine oxidoreduction of oestrogens in the control exercised over this organ by these steroids.

The mode of action of homocysteine on mouse brain glutamic decarboxylase and γ-aminobutyrate aminotransferase

1977 ◽  
Vol 55 (9) ◽  
pp. 1013-1018 ◽  
Author(s):  
G. Tunnicliff ◽  
T. T. Ngo
Keyword(s):  
Amino Acid ◽  
Mouse Brain ◽  
Mode Of Action ◽  
Acid Metabolism ◽  
Competitive Inhibition ◽  
The Other ◽  
Aminobutyric Acid ◽  
Aminobutyrate Aminotransferase ◽  
Dual Action

In the belief that homocysteine-induced convulsions might be related to alterations in brain γ-aminobutyric acid metabolism, we have studied the action of this amino acid on the activity of glutamic decarboxylase (GAD, EC 4.1.1.15) and γ-aminobutyrate aminotransferase (EC 2.6.1.19)of mouse brain in vitro. DL-homocysteine competitively inhibited GAD with respect to both L-glutamate and pyridoxal 5′-phosphate. The respective Ki's were 3.8 mM and 0.3 mM, The activity of GABA-T also was altered in the presence of DL-homocysteine. A competitive inhibition (Ki = 6 mM) was observed with γ-aminobutyric acid, and an uncompetitive inhibition with respect to pyridoxal 5′-phosphate and α-ketoglutarate. These results are explained in terms of a dual action of homocysteine on each of the enzymes: one involving a competition for substrate binding site and the other involving the formation of an inactive inhibitor – cofactor complex. The significance of the inhibition of these enzymes of γ-aminobutyric acid metabolism is discussed in relation to the convulsant action of homocysteine.

scholarly journals Quercetin influences in vitro maturation, apoptosis and metabolically active mitochondria of goat oocytes

Zygote ◽  
2018 ◽  
Vol 26 (6) ◽  
pp. 465-470 ◽  
Author(s):  
A.A.A. Silva ◽  
M.N.P. Silva ◽  
L.B.F. Figueiredo ◽  
J.D. Gonçalves ◽  
M.J.S. Silva ◽  
...  
Keyword(s):  
In Vitro Maturation ◽  
Cumulus Cells ◽  
Lower Proportion ◽  
The Other ◽  
Mitochondrial Activity ◽  
Base Medium

SummaryThe present study aimed to investigate the effect of quercetin as an alternative antioxidant to cysteamine on in vitro maturation. Oocytes were collected from goat ovaries, destined for in vitro maturation and distributed into three groups: CIS group, oocytes were immersed in MIV base medium; in Groups Q4 and Q8, oocytes were immersed in the medium of the CIS group, adding 4 μM or 8 μM of quercetin, respectively, and cultured for 24 h at 38.5°C with 5% CO2. The CIS and Q4 groups presented the same percentage of expanded cumulus cells, but the per cent in the Q8 group was significantly lower than that of the other groups (P<0.05). The oocyte retraction rate in the Q8 group was higher (P<0.05) than in the CIS and Q4 groups. Treatment with 8 μM of quercetin presented a lower proportion of expanded oocytes than the CIS group and 4 μM of quercetin (P<0.05). The percentage of MII oocytes was higher in the Q4 group than in the CIS group (P<0.05), but the percentages in the CIS and Q8 groups were similar. The rate of apoptosis was higher in the CIS group than in the other groups (P<0.05). In addition, oocytes matured with 4 μM quercetin showed higher mitochondrial activity than matured oocytes in the CIS and Q8 groups (P<0.05). In conclusion, 4 μM of quercetin can be used as an alternative to cysteamine in the in vitro maturation of goat oocytes.

THE MODE OF ACTION OF ANTITHYROID DRUGS: RESULTS WITH TWO IN VITRO TESTS

1953 ◽  
Vol 9 (2) ◽  
pp. 224-231 ◽  
Author(s):  
W. R. PITNEY ◽  
T. RUSSELL FRASER
Keyword(s):  
Mode Of Action ◽  
Potassium Thiocyanate ◽  
The Other ◽  
Antithyroid Drugs ◽  
In Vitro Tests ◽  
Maximal Inhibition ◽  
Inhibitory Potency ◽  
Different Types ◽  
Oxidative Iodination

1. Two in vitro tests are described for measuring the inhibitory potency of antithyroid drugs on enzymic and non-enzymic oxidative iodination of protein; one, a milk enzymic iodination test, and the other an enzyme-free peroxide iodination test. 2. Five recognized antithyroid drugs have been tested: 2-thiouracil, 2-carbethoxythio-methyl-glyoxaline, potassium thiocyanate, resorcinol and sulphathiazole. By means of the milk enzymic test they could be ranged in order of potency, as indicated by the molar concentrations required for 50 % inhibition. They could also be separated into different types by the speed with which they pass from minimal to maximal inhibition with rising molar concentration. 3. With the enzyme-free peroxide test, thiouracil, but not resorcinol, was found to be inert; with the enzymic test, both were nearly equivalent in potency.

MODE OF ACTION OF TESTOSTERONE PROPIONATE ON THE SECRETION AND RELEASE OF LUTEINIZING HORMONE (LH) IN THE CASTRATED RAM

1970 ◽  
Vol 63 (2) ◽  
pp. 290-298 ◽  
Author(s):  
Jean Pelletier
Keyword(s):  
Mode Of Action ◽  
Testosterone Propionate ◽  
Single Injection ◽  
The Other ◽  
Control Group ◽  
Treatment Control ◽  
Lh Secretion ◽  
Group D ◽  
Treatment Control Group

ABSTRACT The mode of action of a single injection of testosterone propionate on LH secretion and release has been studied in the castrated ram. In the first experiment, six castrated rams were injected intramuscularly with 400 mg of testosterone propionate, and the plasma LH levels were assayed by radioimmunoassay: on the first day after treatment, the plasma LH levels decreased significantly (P < 0.001), then remained at a very low level for 5–7 days; initial LH levels were restored by day 9. Testosterone propionate thus blocks the discharge of LH. A second experiment was then performed. Castrated rams in groups of 3 were killed either without treatment (control group D0), or 2, 7 or 9 days after the injection of testosterone propionate (groups D2, D7 and D9). In addition to the plasma LH, hypophyseal LH and hypothalamus LRF (LH releasing factor) were measured: the LRF activity was assessed by the quantity of LH released in vitro from the hypophysis of castrated rats blocked with testosterone propionate. The LH released into the incubation medium and the hypophyseal LH of the ram were measured by the ovarian ascorbic acid method and by radioimmunology. The results of the plasma LH assays were comparable to those in the first experiment: plasma LH was significantly decreased in group D2, increased in group D7 and was restored in group D9. Hypophyseal levels, on the other hand, increased in groups D2 and D7, but were comparable to the controls in group D9, indicating that the injection of testosterone propionate had little or no effect on LH secretion. Finally, the LRF activity was considerably reduced in group D2 (P<0.001) as compared with the controls (D0), but similar to the control values in group D9. Although secretion appeared normal, the decreased plasma LH levels in group D2 indicated that LRF had not been released; consequently the decrease in LRF observed can be interpreted as being due to an inhibition of its synthesis under the influence of testosterone propionate.

scholarly journals Binding of zinc and calcium to inositol phosphates (phytate) in vitro

1990 ◽  
Vol 64 (1) ◽  
pp. 225-232 ◽  
Author(s):  
C. J. Simpson ◽  
A. Wise
Keyword(s):  
Inositol Phosphates ◽  
Lower Proportion ◽  
The Other ◽  
Binding Affinities ◽  
Inositol Hexaphosphate ◽  
Neutral Ph ◽  
Hydrolysis Of ◽  
Phosphate Groups

Inositol compounds with three to five phosphate groups (IP3–IP5) were produced by hydrolysis of phytate (inositol hexaphosphate, IP6) and their binding affinities for calcium and zinc investigated at neutral pH with relative concentrations that had been found in a range of students' meals. Zn solubility was negligible at many of these concentrations, with less Zn bound to precipitates of Ca-IP6 than Ca-IP5. The capacity to precipitate Zn at these ratios fell between IP5 and IP3. Zn was partially desorbed by soluble chelators (histidine and picolinate), especially when it had been adsorbed to preformed Ca-IP precipitates. A lower proportion of Zn was accessible to soluble chelators from Ca-IP4 than the other compounds. IP3-IP4 were hydrolysed. by phytase more readily than IP5–IP6.

UPTAKE IN VITRO OF [3H]OXYTOCIN BY THE MAMMARY GLAND AND OTHER TISSUES OF THE RAT

1973 ◽  
Vol 58 (2) ◽  
pp. 289-303 ◽  
Author(s):  
SANDRA M. EGAN ◽  
A. LIVINGSTON
Keyword(s):  
Mammary Glands ◽  
Biological Action ◽  
The Other ◽  
Mammary Tissue ◽  
Uterine Tissue ◽  
Pregnant Uterus ◽  
Specific Uptake ◽  
Specific Receptors ◽  
Preferential Uptake

SUMMARY In the presence of 62 μu. or more of [3H]oxytocin/ml there was specific uptake of oxytocin by lactating rat mammary glands in vitro within 400 s under conditions similar to those used in the biossay of oxytocin with rat mammary strips in vitro. This uptake was blocked by pre-incubation with non-radioactive oxytocin. A similar, rapid, specific uptake of oxytocin by uterine tissue in vitro was observed. There was no specific uptake of oxytocin by non-target tissues such as heart and skeletal muscle. Measurements of inulin and water spaces of the tissues showed that, over these short periods of time, diffusion into mammary tissue was much less than into the other tissues. The ratios of uptake of [3H]oxytocin: [3H]inulin and [3H]oxytocin: [3H]water were much higher for mammary tissue than those for other tissues used, indicating a preferential (tissue-specific) uptake. Uterine tissue from stilboestrol-primed rats also showed a preferential uptake of oxytocin, though not as great as that for mammary tissue. It is suggested that the specific uptake of oxytocin by mammary and uterine tissue is due to binding to specific receptors. There was a variation in the specific uptake of oxytocin with the day of lactation of the mammary tissue, and specific uptake was only observed after the 8th day. This could indicate synthesis of receptors during lactation. In a similar way, synthesis of receptors may occur in the non-pregnant uterus due to the influence of exogenous oestrogens, leading to the increase in specific uptake by non-pregnant uterine tissue for oestrogen-primed rats. There is some evidence of more than one type of binding site for oxytocin. Biological action may only be associated with one of these sites.

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.

Behaviour and Quantitation of Extrinsic (Tissue-Type) Plasminogen Activator in Human Blood

1983 ◽  
Vol 50 (02) ◽  
pp. 518-523 ◽  
Author(s):  
C Kluft ◽  
A F H Jie ◽  
R A Allen
Keyword(s):  
Plasminogen Activator ◽  
Venous Occlusion ◽  
Tissue Type ◽  
Functional Assay ◽  
Uterine Tissue ◽  
Tissue Type Plasminogen Activator ◽  
Type Plasminogen Activator ◽  
Baseline Values

SummaryFunctional assay of extrinsic (tissue-type) plasminogen activator (EPA) in plasma on fibrin plates was evaluated. Using specific quenching antibodies, we demonstrated the method to be specific for EPA under all conditions tested. Contributions of urokinases and intrinsic activators were excluded. The quantity of EPA in blood samples, as compared with purified uterine tissue activator, shows 1 blood activator unit (BAU) to be comparable to 0.93 ng.The median values for EPA activity for healthy volunteers were: baseline, 1.9 BAU/ml (n = 123); diurnal, 5.5 BAU/ml (n = 12); DDAVP administration, 11.7 BAU/ml (n = 39); exhaustive exercise, 25 BAU/ml (n = 24); venous occlusion (15 min), 35 BAU/ml (n = 61). A large inter-individual variation in EPA activity was found, while individual baseline values tended to be constant for periods of weeks.In vitro in blood EPA activity shows a disappearance of 50% in about 90 min at 37° C; EPA activity in euglobulin fractions is stable for ≤2 hr at 37° C.A rapid decrease in EPA activity occurs in vivo, as noted after extracorporal circulation and exercise stimulation (t½ decay, 2-5 min).

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.

Sign in / Sign up

Export Citation Format

Share Document