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Biomedical subjects

S Tojo

Publications and source records attributed to S Tojo.

At least 127 records · Page 7Linked to original sources
PubMed1982

[Failure of positive feedback in hypothalamo-pituitary-system in aged women and its recovery with estrogen treatment].

The positive feedback function of the hypothalamo-pituitary system in aging women was investigated by means of intravenous injection of conjugated estrogens. Marked LH surge was observed in both sexually mature young (20-35 y.o.) and premenopausal (35-49 y.o.) women after the intravenous injection of 20mg of conjugated estrogens. However, merely a small LH surge was observed in postmenopausal climacteric (50-55 y.o.) women, and no LH surge in aged (over 56 y.o.) women. In the patients with hypergonadotropic hypogonadism who are in the same age as sexually mature women, no LH surge was induced by conjugated estrogens. But positive feedback test done after oral administration of conjugated estrogens (1.25 mg/day) for 14 days showed positive reaction in both the aged women and the patients with hypergonadotropic hypogonadism in whom no LH surge had been observed before estrogen priming. The present results suggest that the dysfunction of positive feedback in aged women is mainly due to the decreased levels of estrogen produced by the ovaries but not the primary organic or functional changes of the hypothalamus or the pituitary.

Adult↗
PubMed1981

[Biological and biochemical properties of human chorionic gonadotropin from urine of patients with hydatidiform mole and its radioimmunoassay (author's transl)].

Human chorionic gonadotropin (hCG) was extracted and purified from the urine of four patients with hydatidiform mole. The immunological activities of the hCG-hydatidiform mole by hCG radioimmunoassay (RIA) ranged from 9,380 to 9,700 IU/mg, and the biological activities measured by the immature rat ovarian weight method ranged from 7,250 to 7,780 IU/mg. The results of the amino acid compositions of all the hCG-hydatidiform moles were practically identical with those of hCG-normal pregnancies. The carbohydrate moiety of the hCG-hydatidiform mole was also suspected to be almost similar to that of hCG-normal pregnancies by the results of their in vitro and in vivo biological activities. It was demonstrated that hCG-hydatidiform mole was composed of alpha and beta subunits (similar to a hCG-normal pregnancy) when hCG-hydatidiform mole was separated into subunits by SDS disc electrophoresis after treatment with mercaptoethanol. The RIA system of hCG-hydatidiform mole can be established. The concentrations of hCG in sera of normal pregnant women and patients with trophoblastic diseases assayed by hCG-hydatidiform mole RIA were equivalent to those obtained by a standard hCG RIA. Hence, a standard hCG-immunoassay method used in the management of hCG is concerned.

Adult↗
PubMed1981

Cyclic nucleotides and cellular kinetics in normal and abnormal human trophoblastic tissue.

The ability to synthesize DNA and the cell cycle of normal trophoblastic cells and the trophoblastic cells of hydatidiform moles and invasive moles were studied by the autoradiographic technique. Compared with normal trophoblast, hydatidiform moles or invasive moles had a higher ability to synthesize DNA. cAMP tended to inhibit DNA synthesis in normal and molar tissue, whereas cGMP tended to promote it. The cell cycle time for each type of trophoblastic tissue was roughly 15 h; however, as compared to normal trophoblast, the hydatidiform or invasive moles had a longer S phase and a shorter G1 phase.

Autoradiography↗
PubMed1981

Release of human chorionic gonadotropin (hCG) and its alpha-subunit (hCG-alpha) from perifused human placenta.

The release of human chorionic gonadotropin (hCG) and its alpha-subunit (hCG-alpha) from the normal human placenta and the effect of some stimulatory agents on their release were studied in vitro using a perfusion system. Each perfusate was assayed for hCG and hCG-alpha in its own homologous radioimmunoassay systems. Both hCG and hCG-alpha were released from the placenta at any stage of gestation in our perfusion system. Much more hCG than hCG-alpha was released from the placenta in early gestation. By comparison, however, hCG-alpha increased gradually with the gestational age. The amount of hCG-alpha released was almost equal to that of hCG in the placenta in the 17th gestational week. After the 22nd gestational week, hCG-alpha was released in larger quantities than hCG, and about 10 times more hCG-alpha than hCG was released from the term placenta. These results were also confirmed by gel filtration of perfusates on a Sephadex G-100 column. hCG-alpha, compared with hCG, was present in excess in gel filtrated perfusates in the last two trimesters. By adding 1 mM dibutyryl cyclic AMP to the perifusion medium, the release of both hCG and hCG-alpha was stimulated significantly. Synthetic luteinizing hormone releasing hormone (LH-RH) at concentrations of 10 ng/ml and 100 ng/ml had no effect, but at a high concentration (1 microgram/ml), LH-RH stimulated the release of them. Moreover, mouse epidermal growth factor (EGF) stimulated not only the release of hCG and hCG-alpha but also their production, because both hCG and hCG-alpha levels rose progressively with the time course in the presence of EGF. The present studies demonstrate that the perifusion system of chorionic tissues is a useful method for investigating the release of hCG and its subunits in vitro.

Bucladesine↗
PubMed1981

[Studies on ontogenesis and the regulatory mechanism of hPL binding factor (hPL receptor) in rat liver (author's transl)].

Ontogenesis of hPL binding factor and its regulatory mechanism were investigated in rat liver cell membranes. The results were as follows: 1) Binding of hPL was very low in liver cell membranes from fetal and immature rats. It began to increase after 28 days of age. It increased over control level at mid-pregnancy (L12), reaching more than 300--400% of control level in late pregnancy. It decreased immediately to control level within 24hrs. after parturition. 2) Among the rats treated with estradiol-17 beta, those with progesterone, or those with hydrocortisone, the binding showed a dose-dependent increase in the rats treated with estradiol but no significant change in the others. Combined administration of estradiol and dexamethasone suppressed the binding increased by estradiol completely. 3) The binding was not be able to detected 7 days after hypophysectomy in rats. hPL treatment with PVP (polyvinylpyrrolidone) could restore them. On the other hand, estradiol-17 beta treatment failed to restore. 4) Estradiol-17 beta, progesterone, corticosterone, rPRL, and rCM (rat chorionic mammotropin) were measured in rats in pregnancy. The level of rCM elevated with two peaks at mid-pregnancy and at near term. The other hormones were not changed. In conclusion, hPL binding factor (hPL receptor) in rat liver cell membrane have an intimate relation with maturity and pregnancy. The receptor or its function may be induced by hPL itself and estrogen, but suppressed by glucocorticoid.

Animals↗
PubMed1980

Inhibitory effect of progesterone on follicular growth and induced superovulation in the rat.

We investigated the effect of exogenous progesterone on follicular growth and pregnant mares' serum gonadotropin and human chorionic gonadotropin (PMS-HCG) induced superovulation in intact and hypophysectomized immature rats. Although the administration of progesterone during PMS-HCG injections had no effect on superovulation, the administration of progesterone beginning 3 days before PMS injection inhibited superovulation in both intact and hypophysectomized rats. In order to study the mechanism of inhibition of superovulation by pretreatment with progesterone, an autoradiographic study using tritiated thymidine was done in hypophysectomized rats just before PMS injection. The labelling indices of granulosa cells were significantly decreased by the administration of progesterone (p < 0.001). Treatment with progesterone resulted in an increase of the follicles in early stages of atresia with pycnotic nuclei in granulosa cells surrounding apparently normal oocytes. Ovarian histology and serum and ovarian tissue concentrations of estradiol were then examined in hypophysectomized rats 20 h after HCG injection. Large Graafian follicles and corpora lutea were rarely seen in rats previously given progesterone, whereas many large Graafian follicles and corpora lutea were observed in the control rats. The concentrations of estradiol in the progesterone-pretreated rats were significantly reduced in serum (p < 0.02) and slightly reduced in ovarian tissues when compared with controls.

Animals↗
PubMed1980

[Effect of human chorionic somatomammotropin on release of glucose by perfused rat liver (author's transl)].

The biological action of hCS was studied in non-recirculating perfusion system of the pregnant rat liver. A modified method of Mortimore and of Millor for the liver perfusion was used. The perfusate was prepared with Krebs-Ringer bicarbonate buffer with the addition of BSA (2%), glucose (10 mM) and human erythrocytes (Ht. 12%). The results were as follows. 1) The biological condition of the liver remained good during 90 minutes of perfusion as judged by its gross appearance, O2 consumption, CO2 production, bile secretion and the levels of transaminase, K+, pH in effluent and the microscopic observation after the perfusion. 2) An addition of hCS (20 micrograms/ml) to the perfused pregnant liver resulted in a momentary increase of glucose, FFA and K+ concentration in the effluent. 3) The elevation of the glucose level was also observed after the repeated administration of hCS. This release of glucose from perfused liver after hCS administration took, place more rapidly with the progress of the pregnancy. 4) The elevation of glucose level was maintained longer by the continuous administration of hCS (10 micrograms/ml). 5) Hepatic glycogen decreased after the continuous administration of hCS, but it increased in the control group. The level of cyclic-AMP in the perfused liver rose after the continuous administration of hCS.

Animals↗
PubMed1980

[Renin and aldosterone during pregnancy (author's transl)].

Systematical determination of renin activity (PRA) and aldosterone concentration (PA) in blood of normal and hypertensive pregnant women was done. At the same time, reactive change of PRA and PA to NaCl loading was studied, and the authors gained the following conclusions: 1) In normal pregnant women a significant increase was observed respectively in PRA and PA in comparison with those observed in non-pregnant status (PRA: P less than 0.05, PA: P less than 0.02). A peak (11.85 ng/ml/hr) was formed in PRA at the 32nd week of pregnancy, while in PA an increase lasted until the start of labour, attaining a level of 563.3 pg/ml (mean value). 2) PRA and PA in toxemia of pregnancy were obviously lower in comparison with normal pregnancy in the corresponding period. Analysis by the two dimensional cordinate system in which PA value was represented by axis of abscissas and PRA value by axis of ordinate disclosed that hypertensive toxemia of pregnancy tended to be distributed among patients with low PRA while non-hypertensive toxemia of pregnancy was distributed among patients with low PA. 3) In non-pregnant women and those in the first trimester, no noticeable change was displayed by NaCl load either in PRA or in PA, but the reactivity became obvious along with advancement of pregnancy and a high reactivity was shown by pregnant women who were positive in the so-called roll-over test. Also when women whose blood pressure rose to 140/90 mmHg or above after NaCl loading were classified as those positive in NaCl loading test, all the normal pregnant women were negative, but among the patients with hypertensive pregnancy, a positive reaction was represented in half of them in spite of the treatment. The above signifies that the PRA and PA were different in their behaviors in the third trimester, and in the value of PA, participation of aldosterone deriving from fetus was suggested. Analysis of PRA and PA by the two dimensional cordinate system and analysis of the behavioral reaction in NaCl loading test were supposed to be clinically useful for classification of the clinico-pathological types of toxemia of pregnancy.

Adult↗