[The effect of enzymes on progesterone-receptor binding and chromatin binding of the complex in the estrogen-primed rabbit uterus (author's transl)]

The present study was designed to determine the characteristics of the progesterone receptor and chromatin binding site ("acceptor") of the progesterone-receptor complex in the rabbit uterus. The uterus was obtained from an estrogen-primed immature female rabbit. The binding of progesterone to the uterine receptor was examined in vitro. The progesterone-receptor binding was reduced only by proteases, and phosphorus moiety may not be related for progesterone-receptor binding. The effects of enzymes on the acceptor of the chromatin were investigated. The progesterone-receptor complex was bound to the dehistonized chromatin. The dehistonized chromatins, which were pretreated with enzymes at 4 degrees C or 37 degrees C for 30 minutes, were incubated with 3H-progesterone prelabeled uterine cytosol at 4 degrees C for 30 minutes, and the radioactivity in the chromatin pellet was counted. Proteases effectively decreased the receptor binding capacity to the dehistonized chromatin in the following order: pronase greater than trypsin greater than papain greater alpha-chymotrypsin. DNAse moderately and phospholipase A slightly decreased its binding capacity. The results may indicate that the acceptor site of the progesterone receptor is nonhistone protein over DNA of chromatin and may contain phosphorus moiety.

Preliminary studies on streoid-binding proteins in human testes of testicular feminization syndrome

This study was designed to detect either 5alpha-dihydrotestosterone (DHT) or 17beta-estradiol (E2)-binding protein in the testes of a 1-year-old patient with testicular feminization syndrome (TFS) and in the testes of patients with prostatic cancer. Sucrose gradient analyses revealed E27S protein binding (but no such 7S protein binding of DHT) in the testes of the patient with TFS, but both E2 and DHT 7 S protein binding was observed in normal senile testes. The dissociation constants (Kd) were measured by charcoal adsorption. The Kd of E2 protein binding in both testes of different status was approximately 1.3 x 10(-9) M, and the Kd of DHT protein binding was 2.0 x 10(-9) M in the senile testes. A ligand specificty study indicated characteristics of both E2 and DHT receptors in the senile testes. It is speculated that a deficiency of androgen receptor and the presence of estrogen receptor in the testes of patients with TFS lead to insensitivity to androgen as a result of the androgen receptor deficiency and to sensitivity to estrogen as a result of the presence of the estrogen receptor.

Mechanism of antiprogestational action of synthetic steroids

This study was designed to investigate the mechanism of antiprogestational action of synthetic steroids, danazol (17α-hydroxy-pregn-4-en-20-yno [2,3-d] isoxazol-17-ol) and R2323 (13β-ethyl-17α-hydroxy-18,19-dinor-17α-pregna-4,9,11-trien-20-yn-3-one). Oestrogen primed rabbit uteri were used for this study. The sucrose gradient analysis in the supernatant of 248 000 x g (max.) of the uterine homogenate showed that progesterone8S binding was inhibited by each of the synthetic steroid, and the kinetic study revealed that each steroid was a competitive inhibitor, where Kd of progesterone-protein binding was 8.1 × 10−10 m, Ki of danazol-protein binding was 2.7 × 10−8 m and Ki of R2323-protein binding was 6.6 × 10−9m. These results indicate that these synthetic steroids bind to progesterone receptor with moderate binding affinities. The modified Anderson's exchange assay of nuclear receptor demontrated that danazol- or R2323-receptor complex can enter into the uterine nuclei in a lesser degree than does progesterone-receptor complex. RNA synthesis by the uterine chromatin was stimulated if the progesterone-receptor complex was added, but this stimulation was inhibited by addition of danazol or R2323. The chromatin RNA transcription was not induced by danazol- or R2323-receptor complex.

These results suggest that such a synthetic steroid binds to a progesterone receptor, and the steroid-receptor complex enters into the nucleus but does not activate the chromatin template, thus resulting in the antiprogesational effect.

Progesterone receptor in human endometrium of leiomyoma uteri

This study was designed to examine whether 8S protein as progesterone receptor exists in the human endometrium which has been primed with estrogen. The kinetic study showed that 8S-progesterone binding was specific with Kd of 2.0 X 10(-9) M. 5S-progesterone binding was inhibited competitively by cortisol. The study of ligand specificity also showed that progesterone and its related steroids had much stronger affinity for 8S component than for 5S component. Therefore, 5S protein may be CBG. Progesterone-8S protein binding was easily dissociated during the 5-20% sucrose gradient centrifugation, but such a protein from which progesterone had been dissociated could be sedimented at 8S region. Glycerol could stabilize progesterone-8S protein binding. These results indicate the existence of 8S protein as a progesterone receptor under the low salt medium in the estrogen primed human endometrium.

Contribution of functional groups of 19-nor-progestogens to binding to progesterone and estradiol-17beta receptors in rabbit uterus

The structural elements of 19-norprogestogens which may be essential for binding to progesterone and estradiol-17beta(E2) receptors were investigated in the rabbit uterine cytosol. The kinetic study showed that 19-nor-progestogens are competitive inhibitors of progesterone-receptor (8S) binding and E2-receptor binding. The affinities of steroids for the progesterone receptor were as follows: norethindrone (Ki of 2.3 X 10(-9)M) greater than 5alpha-dihydronorethindrone greater than norethindrone acetate greater than lynestrenol greater than 17alpha-ethynyl-estra-4-ene-3beta, 17beta-diol greater than ethynodiol diacetate (Ki of 1.3 X 10(-7) M). The affinities of steroids for the E2 receptor were as follows: ethynodiol diacetate (Ki of 1.3 X 10(-7)M) greater than 17alpha-ethynyl-estra-4-ene-3beta, 17beta-diol greater than norethindrone acetate greater than norethindrone greater than 5alpha-dihydronorethindrone greater than lynestrenol (Ki of 8.4 X 10(-7)M). The results indicate that 3-ketone and 17beta-hydroxyl groups, and the plane of ring A/B of 19-norprogestogen are important for binding to the progesterone receptor. The affinities of 19-nor-progestogens for the E2 receptor were very weak. Their affinities for the E2 receptor increased with addition of acetate or hydroxyl groups at the 3beta and 17beta positions, and were decreased by the elimination of a 3 oxygen function or the reduction of ring A.

The mechanism of action of the copper intrauterine device

The effects of copper ions on the binding of steroids to receptors revealed that the inhibitory effect of Cu++ was apparent at 10(-6)M, ANd the binding capacities decreased to 10% at 10(-2)M Cu++. The kinetic study demonstrated that Cu++ was a competitive inhibitor of steroid hormone-receptor binding (Ki divided by 2.7 X 10(-5)M to estrogen receptor; Ki divided by 5.1 X 10(-6)M to progesterone receptor). These results indicate that copper ions interfere at the steroid-binding site of receptor and that progesterone receptor is more affected by copper ions than is estrogen receptor. The sedimentation pattern showed the dissociation and aggregation of receptor macromolecules by copper. These phenomena may indicate the biologic inactivation of receptor. In fact, morphologically, progestational proliferation was severely inhibited and estrogenic action seemed to be inhibited. The Timm stain showed copper uptake by endometrial epithelium and superficial stromata. The copper content apparently increased in the cytoplasm of uteri bearing a copper intrauterine device, compared with controls. In vivo, the concentration of cytoplasmic copper was approximately 1.4 X 10(-6)M, which was obviously inhibitory to steroid hormone-receptor interaction. However, complete morphologic suppression of the progestational effect by copper cannot exclude the coexistence of some other mechanism in these phenomena.

Echocardiography and angiocardiography for detection of left atrial thrombosis

Diagnostic capabilities for detection of the left atrial clot in patients with mitral stenosis were compared between echocardiography and angiocardiography. Large clots in the left atrial body were correctly diagnosed either by echocardiography or by angiocardiography. Clots in the left atrial appendage were not disclosed by echocardiography. Left atrial visualization with pulmonary arteriography offers only possible diagnosis of the clot in the appendage. Definite diagnosis of the clot in this location requires transseptal left atriography.

[Interaction of norethindrone on estrogen and progesterone receptors in the rabbit uterine cytosol (author's transl)]

Norethindrone (ENT), which is a representative in estrane series of progestogen, is not only strongly progestational but also estrogenic and in some cases, antiestrogenic. To understand progestational effect and antiestrogenic effect, the interactions of ENT on estrogen and progestogen receptors were studied in the uterine cytosol of white female rabbit. The 274,200 X G supernatant of uterine homogenate was used as cytosol. 3H-Estradiol, 3H-Progesterone, 3H-ENT or cold ENT were incubated with uterine cytosol at 4 degrees C for 2 hours. Results are as follows: 1. Sucrose gradient centrifugation [5 approximately 20% linear and 40,000 rpm (159,200 X G) for 16 hours at 4 degrees C]: ENT was bound to extrogen 8S receptor in immature rabbit uterus (Fig. 2 & 3), and to progestogen 8S receptor in estrogen primed rabbit uterus (Fig. 5). 2. Kinetic study, determined by dextran coated charcoal (0.001% dextran and 0.1% charcoal): (1) In the uterine cytosol of immature rabbit, 3H-estradiol-receptor binding was observed with Kd divide by 3.6 X 10-9 M and it was revealed that ENT was a competitive inhibitor to this binding with Ki divide by 2.6 X 10-6 M, as in Fig. 6. (2) 8S component, obtained by centrifugation of uterine cytosol (Fig. 1) in estrogen primed rabbit, binds 3H-progesterone with Kd divide by 8.1 X 10-10 M and Bm (maximal binding sites) divide by 5.0 X 10-8 M/mg of protein, and ENT was a competitive inhibitor in this binding with Ki divide by 2.3 X 10-9 M (FIG. 7 & 8). 3H-ENT-8S binding was demonstrated with Kd divide by 1.1 X 10-9 M and Bm divide by 8.7 X 10-8 M/mg of cytosol protein (Fig. 8). These results indicate: (a) ENT is bound to both estrogen and progestogen receptors in 8S macromolecules of uterine cytosol, (b) competitive inhibition of ENT to these bindings indicated that ENT is bound to these receptors at the steroid binding sites where estradiol and progesterone bind to, (c) ENT has much more affinity to progestogen receptor (Ki divide by 2.3 X 10-9 M) than to estrogen receptor (Ki divide 2.6 X 10-6 M), (d) while ENT is bound to progestogen and estrogen receptors at the same time, Bm of ENT (8.7 X 10-8 M/mg of cytosol protein) is more than Bm of progesterone (5.0 X 10-9 M/mg of cytosol protein), and Kd of ENT (1.1 X 10-9 M) was less than Ki of ENT (2.3 X 10-9 M) in the binding to progesterone-receptor. Biologically, while ENT is bound to progestogen -receptor with high affinity and to estrogen receptor with low affinity, ENT is actually progestational in low dose and antiestrogenic in high dose but the anti-estrogenicity seems to be incomplete in vivo as ENT may be metabolized to a potent estrogenic compound, ethinyl estradiol

[The effect of metallic ions on steroid hormone receptors in the rabbit uterus (author's transl)]

The copper-IUD has been proved to be more effective for contraception than the popular IUD. To understand this mechanism of action, the effects of metallic ions on estrogen and progesterone receptors were examined in the cytosol of estrogen primed with female rabbits. The 274,200 X G supernatant of the uterine homogenate was used as the cytosol. The cytosol and 3H-progesterone (3.12 X 10(-9)M) or 3H-estradiol-17 beta (3.46 X 10(-9)M), with or without various metallic ions of different concentrations had been incubated for 2 hours. Bindings of steroids were estimated by the dextran coated charcoal assay (0.001% dextran and 0.1% Norite A) and were evaluated by 5 approximately 20% sucrose linear gradient centrifugation 1) Effect of various metallic ions on steroid hormone-receptor binding (determined by dextran coated charcoal assay. Fig. 1) : Thesteroid hormone-receptor interactions were markedly inhibited by Cu++, Fe++, and Zn++ ions and moderately by Mn++, but K+ and Ca++ increased of slightly affected the binding at concentrations between 10(-2)M and 10(-4)M. There were some differences between estrogen and progesterone receptors in their sensitivities to various metallic ions. 2) The effect of copper ion on the binding of steroid to the receptor : The dextran coated charcoal assay (Fig. 2) demonstrated that the inhibitory effect of Cu++ appeared at 10(-6)M and the steroidhormone-receptor bound decreased down to 10% at 10(-2)M Cu++. The estrogen receptor was less affected by copper than the progesterone receptor. It was demonstrated by 5 approximately 20% sucrose linear gradient centrifugation (Fig 3) that estrogen and progesterone receptors, which both sedimented at 8 S, were changed to more sedimenting forms in the presence of 10(-4)M Cu++, and were dissociated to 6.5 S form with moderate loss of steriod hormone binding affinity in 10(-2)M Cu++. The kinetic study (Fig 4), determined by dextran coated charcoal, showed that Cu++ was a competitive inhibitor against steroid hormone receptor bindings with Ki in equilibrium 2.7 X 10(-5)M to estrogen receptor (Kd in equilibrium 1.4 X 10(-9)M), and with Ki in equilibrium 5.1 X 10(-6M to progesterone receptor (Kd in equilibrium 8.1 X 10(-10)M). These results indicate the inhibiting factor of copper is the direct interference at the steriod binding site of the receptor, resulting in the increase in the effectiveness of the IUD. While progesterone receptor is more affected by copper ion than estrogen receptor, it is suggested that estrogen receptor survives longer than progesterone receptor and thus the biolgoical effect of copper seems to be somewhat estrogenic.