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Biomedical subjects

S Tojo

Publications and source records attributed to S Tojo.

At least 109 records · Page 6Linked to original sources
PubMed1982

[Gonadotropin and plasma cyclic nucleotides].

Plasma cyclic nucleotides in some physiological conditions were measured in normal women and the changes of cyclic AMP were studied after the loading of gonadotropins in normal and castrated women. We demonstrated a circadian rhythm of cyclic AMP and its variation during menstrual cycle in normal women and also demonstrated its significant increase in pregnant women. But there was no significant variation of plasma cyclic GMP levels in those physiological conditions. Plasma cyclic AMP was increased by the simultaneous administration of HMG and HCG in both normal and castrated women. However, individual administration of HMG or HCG demonstrated that it was HCG that caused that increase in plasma cyclic AMP even in castrated women. To examine the extragonadal effects of HCG, cortisol, triiodothyronine (T3), thyroxine (T4) in the plasma were measured after the loading of HCG. The plasma cortisol level was influenced by HCG in neither normal nor castrated women. HCG did not cause any change of T3 or T4 in normal women; however it caused a marked increase in T3 with a small decrease in T4 in castrated women.

Chorionic Gonadotropin↗
PubMed1982

[Insulin Receptor in human placenta and its function].

Characteristic of insulin receptor in human placental villi with relation to glucose uptake and glycogenesis was studied in vitro. The specific binding of 125I-insulin to placental villi membranes was measured significantly higher in early placenta than in term placenta, while Scatchard plots analysis showed curvilinear, which indicated the binding affinity was approximately the same between them. However the binding capacity was higher in early placenta than in term placenta. The addition of insulin to placental villi in vitro showed increased glucose uptake, glycogen content and glycogen synthetase I form activity both in early and term placental villi. The glucose uptake, glycogen content and glycogen synthetase (total and I form) activity were higher in early placental villi than in term placental villi, but there was no significant difference in glycogen phosphorylase (total and active form). Collectively, the data suggest the presence of insulin receptor in placental villi varying its concentration with gestational age, where insulin plays a role in adjusting glucose uptake and glycogenesis.

Chorionic Villi↗
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↗