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Biomedical subjects

S Tojo

Publications and source records attributed to S Tojo.

At least 73 records · Page 4Linked to original sources
PubMed1982

Multiple inhibitory effects of a luteinizing hormone-releasing hormone agonist on hCG-dependent steroidogenesis and on FSH-dependent responses in ovarian cells in vivo and in vitro.

[125I] labelled [D-Leu6, des-Gly-NH10(2)] LH-RH ethylamide (LH-RHa), when injected into immature female rats, bound specifically not only to the pituitary but also to the ovaries. LH-RHa inhibited hCG-stimulated progesterone production and ovarian weight augmentation in hypophysectomized immature female rats in vivo. FSH-induced ovarian hCG receptors and ovarian weight gain in diethylstilbestrol (DES)-treated hypophysectomized immature female rats were also suppressed by LH-RHa. Progesterone production by rat luteal cells in vitro was inhibited by LH-RHa. LH-RHa did not change the affinity or population of LH/hCG receptor in porcine granulosa cells in short term incubation. However, LH-RHa inhibited induction of LH/hCG receptor stimulated by FSH and insulin in long term culture of porcine granulosa cells. LH-RHa delayed hCG-stimulated cyclic AMP accumulation in porcine granulosa cells. These findings suggest that LH-RHa inhibits hCG-stimulated cyclic AMP accumulation and subsequent progesterone production as well as FSH-stimulated LH/hCG receptor induction by acting directly on ovarian cells.

Animals↗
PubMed1982

[Discordance of competitive and non-competitive pregnancy tests for human chorionic gonadotropin, as related to alpha subunit producing tumor (author's transl)].

Ectopic production of isolated alpha subunit of glycoprotein hormones(s) in 32-year-old woman with metastatic lung tumor was first detected by a discordance in the immunological pregnancy tests for native human chorionic gonadotropin (hCG). Quantitative discrepancy of titrations among different types of pregnancy test kit, that i, competitive (hemagglutination or latex agglutination inhibition) and non-competitive (hemagglutination or latex agglutination) reactions, was also confirmed by the experimental study using highly purified ectopic alpha-subunit from the patient's urine. Thus, the discrepancy among the two types of assay systems was due by crossreaction of high concentrations (20,000 ng/ml) of ectopically secreted alpha-subunit of glycoprotein hormone(s). We report herein the typical behavior of immunological assay systems for native hCG in determining immunoreactive free hCG-alpha and stress the diagnostic value of the discordance observed in these assay systems.

Adult↗
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↗
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

[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↗
PubMed1979

Immunohistochemical interaction on antisera to HCG and its subunits with chorionic tissue of early gestation.

Immunohistochemical localization of hCG and its subunits in chorionic tissue of early gestation was carried out. Antibodies to purified hCG and its subunits were obtained by using these agents for immunization according to the small doses method. The antibody titers and specificities were examined by B/T and standard curves in homologous radioimmunoassay system. The tissue preparations were stained both by a direct and by an indirect method utilizing these antisera and observing the specimens under a fluorescent microscope. The results were as follows. 1) With the anti-hCG staining, fluorescence was observed in the syncytiotrophoblasts as reported previously while the cytotrophoblast were stained slightly. 2) with the anti-hCG-beta staining, the fluorescence was almost identical with that of hCG and showed a more distinct pattern. 3) with the anti-hCG-alpha staining, the fluorescence was found both in the syncytio- and cytotrophoblasts concurrently. Fluorescence of the latter cells was recognized as due to free alpha-subunit because cytotrophoblast was scarcely stained with anti-hCG and anti-hCG-beta.

Chorionic Gonadotropin↗
PubMed1979

The clinical evaluation of the simultaneous measurements of human chorionic gonadotropin (hCG) and its alpha-subunit in sera of patients with trophoblastic diseases.

The concentrations of human chorionic gonadotropin (hCG) and its free immunoreactive alpha-subunit (hCG-alpha) in the sera of patients with trophoblastic diseases were measured by hCG and hCG-alpha radioimmunoassay (RIA), respectively. In the sera of 12 women with hydatidiform mole large amounts of hCG and considerably high level of hCG-alpha were detected in all cases. After the evacuation of mole the serum level of these glycoproteins decreased, the leve of hCG-alpha declined more rapidly than hcg. in the sera of patients with destructive mole the concentration of hCG-alpha was usually lower than that of hCG. After hysterectomy and chemotherapy the levels of hCG-alpha declined practically paralleling that of hCG. However, when hCG had decreased to undetectable level, hCG-alpha could no longer be detected in all cases. Although in the serum of patient with choriocarcinoma involving the uterus and lungs the concentration of hCG-alpha was almost as high as that of hCG, the secretory pattern of hCG and hCG-alpha might not be closely related. The changes in the serum level of free hCG-alpha as well as that of hCG parelled the clinical course of the patients examined in this study. The present results suggest that measurements of the serum free hCG-alpha may be a useful parameter to follow the clinical course and to evaluate the efficacy of treatments of trophoblastic diseases.

Adult↗
PubMed1979

Diagnostic evaluation of progesterone. Challenge test in amenorrheic patients.

Forty-one amenorrheic patients were grouped on the basis of presence or absence of withdrawal uterine bleeding following the intramuscular administration of progesterone. Ovarian volume, ovarian morphology with particular reference to presence or absence of follicles and state of follicular development, and steroidogenic function were investigated in each group. Most of amenorrheic patients with progesterone-induced uterine bleeding had relatively large ovaries with follicles of high developmental stage (tertiary-Graafian follicle) and responded to exogenously administered HMG and HCG with a rise in the 24-hour urinary excretion of total estrogens. In contrast, most of amenorrheic patients without progesterone-induced uterine bleeding had relatively small ovaries without follicles or with follicles of low developmental stage (primordial-secondary follicle) and did not respond to exogenous HMG and HCG. The results of the present study suggest that presence or absence of progesterone-induced uterine bleeding is closely correlated with the volume, morphology and steroidogenic function of the ovary in amenornorrheic patients. Thus, pathologic amenorrhea could be divided into two groups by utilizing the progesterone challenge test and this clinical categorization might be useful for the diagnosis and treatment of amenorrheic patients.

3-Hydroxysteroid Dehydrogenases↗