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Biomedical subjects

K Hirato

Publications and source records attributed to K Hirato.

31 records · Page 2Linked to original sources
PubMed1984

Enhancement of human amniotic phospholipase A2 activity by steroid-sulphate derived from the foeto-placental unit.

To study the control of production of prostaglandins (PG) during pregnancy and parturition, amniotic membranes obtained from normal vaginal delivery were incubated with the substrate of phosphatidylcholine containing [14C]arachidonic acid in the Sn-2 position. Phospholipase A2 activity was calculated as the rate of release of [14C]arachidonic acid from the substrate. Various steroids were added to the incubation medium to elucidate the effect of steroids on the enzymatic activity. The addition of dehydroepiandrosterone-sulphate (DHA-sulphate) to the medium increased by 7-fold the rate of [14C]arachidonic acid release from phosphatidylcholine at a concentration of 1.67 mM. The enhanced rate of arachidonic acid release suggests that DHA-sulphate stimulates phospholipase A2 activity. The same amounts of pregnenolone-sulphate and oestrone-sulphate also enhanced the enzymatic activity, while cholesterol-sulphate, free steroids such as DHA, progesterone, cortisol and oestrogens revealed no effect. These results suggest that steroid sulphates may be involved in the regulatory mechanism for PG synthesis in amniotic membrane.

Amnion↗
PubMed1984

[Changes in steroids in amniotic fluid in relation to the initiation of labor].

To study the changes in steroid concentrations in amniotic fluid (AF) in relation to the initiation of parturition, eleven steroids in AF which included cortisol(F), progesterone (P4), 20 alpha-dihydroprogesterone, free(f-) and conjugated(c-) pregnenolone, DHA, estradiol(E2) and estriol(E3) were measured by RIA. Experiment 1: Samples were obtained at I) elective cesarean section (not in labor, n = 9), II) vaginal delivery after the spontaneous onset of labor (in labor, n = 13). Experiment 2: AF were collected serially from each individual at A) the artificial rupture of the membrane before the onset of labor, B) the initiation of labor and C) second stage of delivery. Samples of B and C were obtained with a catheter which was placed in the uterine cavity at the rupture of the membrane. The mean concentrations of F,c-E2,f- and c-E3,DHA in I were significantly higher than those in II. In experiment 2, except for P4, all steroid concentrations tended to increase during the course of labor. The levels of F increased significantly from A to C but not from A to B. Free DHA increased from B to C. The percentage increase in steroid levels was also caliculated and it was found that the steroid increase from A to B was f-E2 while P4 decreased. E2/P4 ratio increased significantly from A to B. These results suggested that the increase in F and DHA may be due to the fetal response to the stress of labor. A possible role of increased E2 and decreased P4, and subsequently increased E2/P4 ratio, in AF on the onset of labor is suggested.

20-alpha-Dihydroprogesterone↗
PubMed1984

[Steroid levels and myometrial sensitivity to oxytocin].

To examine the relation between changes in steroid concentrations in serum and myometrium and the uterine sensitivity to oxytocin, sixteen steroids including free and conjugated progesterone, 16 alpha OH-progesterone, 20 alpha OH-progesterone, cortisol, 16 alpha OH-pregnenolone, DHA, 16 alpha OH-DHA, estrone, estradiol, estriol in serum and myometrium were measured simultaneously by RIA. 83 pregnant women near term were selected for this study and steroid levels were measured in 66 cases. There was a significant correlation between days to the onset of labor and myometrial sensitivity to oxytocin estimated by the Smyth test. The levels of 16 alpha OH-progesterone, 20 alpha OH-progesterone, cortisol, 16 alpha OH-pregnenolone, conjugated 16 alpha OH pregnenolone, estrone, estradiol, conjugated estrone, conjugated estradiol, conjugated estriol, conjugated DHA and conjugated 16 alpha OH-DHA increased as the uterine sensitivity to oxytocin increased, while the levels of progesterone decreased significantly. The ratios of 20 alpha OH-progesterone to progesterone and estradiol to progesterone also rose significantly, while the ratio of free to conjugated DHA fell significantly. Serial determination of steroid levels and ratios and sensitivity to oxytocin revealed a similar pattern to that mentioned above. There was a significant correlation between serum and myometrial concentrations of progesterone, 16 alpha OH-pregnenolone, DHA, conjugated DHA, estrone and estradiol. From these results it was concluded that the environment of steroid hormones may be closely related to myometrial sensitivity to oxytocin and the onset of labor.

Estradiol↗
PubMed1984

[Prenatal diagnosis of IUGR by assessing the multiple hormone concentration in maternal peripheral blood].

The serum concentrations of multiple hormones in maternal peripheral vein during pregnancy were simultaneously measured to determine whether it is possible to discriminate IUGR from normal pregnancy. Blood samples were obtained when the patients were at 30 to 35 weeks of gestation and IUGR was confirmed after delivery. The mean concentrations of progesterone and estriol were significantly lower in maternal vein with IUGR than those in normal pregnancy. On the other hand, the mean concentrations of 16 alpha-hydroxypregnenolone and DHA were significantly higher in the patients with IUGR than those in the patients with normal fetus. However, it seemed impossible to discriminate IUGR from normal completely, since the steroid values in IUGR overlapped in normal range. An attempt was made to apply the data to the computation in multivariate analysis. The computer used for this analysis was an HITAC-M-180 and the package was BMD. Using the principal component analysis, normal and IUGR groups were roughly separated. However, no definite border line could be drawn between normal and IUGR. The discriminant analysis was then applied to separate two groups. Using the estriol value as a variable, 58% reliability was achieved in separate two groups. 93% reliability was achieved when the values of 6 steroids were used. And finally, when the clinical data represented by the length of the uterine fundus and the girth were added to the steroidal values, 100% possibility was obtained in separate two groups.

17-alpha-Hydroxypregnenolone↗
PubMed1983

[Steroid metabolism in fetal membrane].

UNLABELLED: In vitro tissue culture and incubation studies were undertaken to study the enzymatic activities for steroidogenesis in human fetal membrane. MATERIALS AND METHODS: Human fetal membrane obtained at term was separated to reflected amnion(RA), placental amnion(PA), chorion laeve(C) and decidua(D). I) Except for D, 5 x 5cm2 of the tissue were cultured in MEM medium with 10% FCS for 8 days. At steroid tracers, 14C-dehydroepiandrosterone(DHA), or 14C-DHA-sulfate(DHA-S) was added and half of the medium was changed every 2 days. II) 800 x g Cell free homogenate was incubated with radioactive DHA-S, pregnenolone-S(P-S) and estrone-S(E-S). Radioactive metabolites in the medium were extracted and identified. RESULTS: Sulfatase activity was found not only in D and C but also in RA and PA. The accumulated products of DHA-S to DHA increased as the number of cultured days increased. Sulfokinase and 17 beta-hydroxysteroid dehydrogenase activities for DHA was also found when PA was cultured. From the results of the kinetic studies on incubation, E-S showed the highest affinity for sulfatase in all tissue. Kinetic studies for sulfatase activity in RA demonstrated that Km values for E-S and DHA-S were 33 and 66 microM, respectively. CONCLUSION: This is the first report to demonstrate the activity of sulfokinase in RA and that of sulfatase in amnion membrane. These results provide further information on the function of fetal membrane which seems to play an important role in the transport and metabolism of steroids in the feto-placental compartment during pregnancy.

Amnion↗
PubMed1982

[A measurement of 5-androstene-3 beta, 17 beta-diol in human serum (author's transl)].

A radioimmunoassay using specific antisera against 5-androstene-3 beta, 17 beta-diol-11 alpha-succinoyloxy-BSA was developed, and serum concentrations of 5-androstene-3 beta, 17 beta-diol (AD) in normal men and women (maternal vein during pregnancy and cord blood at delivery) were measured. The reliability of the method was assessed by means of the recovery rate (97-109%) and the co-efficient of variation of inter- and intra assay (10-14%). The concentrations in serum samples obtained from various sources were as follows (ng/ml of free steroid mean +/- SD): spermatic vein, 48.57 +/- 50.64, peripheral vein in men aged 57-84, 1.24 +/- 0.47; ovarian vein during follicular phase, 3.81 +/- 3.27, peripheral vein, 1.03 +/- 0.44; maternal vein at delivery, 3.03 +/- 0.77, umbilical artery, 6.58 +/- 3.00, umbilical vein, 6.32 +/- 2.82. Plasma AD levels in the spermatic and ovarian vein were significantly higher than in the peripheral vein, suggesting the gonadal secretion of this steroid. Maternal serum AD concentration increased as pregnancy advanced, and AD levels in cord blood at delivery were significantly higher than that in maternal blood. These results also indicate that AD is one of the products of the feto-placental unit.

Adult↗
PubMed1982

A study of 5 alpha-reductase in human fetal brain.

To study 5 alpha-reductase activity in the human fetal tissues, hypothalamus, cerebrum, skin, liver, kidney, small intestine, lung, adrenal and placenta of aborted fetuses at mid gestation were obtained and incubated with labeled delta 4-3-keto steroids under CO gas in the presence of excess NADPH. A higher conversion of progesterone to 5 alpha-pregnanedione was observed in the hypothalamus and cerebrum than in other tissues studied. The major portion of 5 alpha-reductase in the cerebrum was localized in 800 X g precipitate (crude nuclear fraction). Androstenedione and progesterone were found preferred substrate for 5 alpha-reductase to 17 alpha-hydroxyprogesterone or testosterone. Km of 5 alpha-reductase for progesterone and androstenedione were 1.0 X 10(-5) M and 9.0 X 10(-6) M, respectively. The enzyme activity for progesterone was inhibited by estrone and androstenedione but not by estriol.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1982

[A study of 16 alpha OH-DHA and 16 alpha OH-pregnenolone in feto-placental unit (author's transl)].

Serum levels of total 16 alpha-hydroxydehydroepiandrosterone (16 alpha-OH-DHA) and 16 alpha-hydroxy-pregnenolone (16 alpha-OH-P5) which are considered to be a fetal origin have not been well documented. Radioimmunoassays using specific antisera against 16 alpha-PH-DHA-7-CMO-BSA and 16 alpha-OH-P5-#-succinate-BSA were developed and serum concentrations of these steroids in normal men and women, maternal peripheral vein (MV) during pregnancy, umbilical artery and umbilical vein at delivery were measured. Labeled 16 alpha-hydroxylated steroids were synthesized by microbiological method. The concentrations of 16 alpha-OH-delta 5-steroids were increased as pregnancy progresses. Both steroid levels in cord serum were statistically higher than those in MV. In the case of intrauterine fetal death and anencephalic pregnancy, significantly low levels of both steroids in MV and cord blood were found. On the other hand, pregnancy with placental sulfatase deficiency, showed high levels both in MV and cord vein. It is interesting to not that in normal pregnancy, maternal 16 alpha-OH-DHA levels correlated well with that of 16 alpha-OH-P5. However, in pregnancy with anencephalic fetus, there was no correlation between the levels of two steroids. From the results of in vitro experiment using placental tissue, 16 alpha-OH-progesterone was formed from labeled 16 alpha-OH-P5, whereas no metabolite was noticed when fetal adrenal tissue was used. From these in vitro and in vivo studies, a significance of the measuring of serum 16 alpha-OH-DHA and 16 alpha-OH-P5 during pregnancy is discussed.

17-alpha-Hydroxypregnenolone↗
PubMed1982

[Difference of steroidogenesis in human ovary at different stage of cycle (author's transl)].

This experiment was undertaken to compare the steroidogenesis in human ovary at different stage of the cycle. Fifteen subjects, 8 in follicular, 7 in luteal phase were selected for this study. On hysterectomy, both ovarian and peripheral venous blood were collected simultaneously and follicle or corpus luteum were obtained. Steroid levels including pregnenolone(P5) 17 alpha-OH-P5, DHA, androstenediol (AD), progesterone(P4), 17 alpha-OH-P5, androstenedione(delta 4A) and testosterone(T) were measured by radioimmunoassay. Tissue were homogenized and incubated with labeled P5, 17 alpha-OH-P5, DHA and AD in the presence of NAD t 37 degrees C. As gas phase, CO was used. Metabolites were extracted and separated by TLC. 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity was expressed as the amounts of delta 4-steroid formed from corresponding delta 5 substrate. The levels of P5, P4, 17 alpha-OH-P4, DHA, delta 4A, T in the ovarian vein and the concentration of P5, 17 alpha-OH-P5, DHA, P4, 17 alpha-OH-P4, T in the ovarian tissue obtained in luteal phase were significantly higher than that in follicular phase. The results suggested that the delta 5 pathway seem to be active in corpus luteum. In follicular phase, highest concentration of 17 alpha-OH-P5 among delta 5 in ovarian vein and 17 alpha-OH-P4 among delta 4 steroid in ovarian vein and tissue was noticed. 3-beta-HSD activity was lower in follicle than that in corpus luteum. Substrate specificity was noticed in 3 beta-HSD in follicle and it was found that 17 alpha-OH-P5 seemed to be the most potent substrate for the enzyme. The difference of steroidogenesis between follicular and luteal phase was demonstrated in human ovary.

3-Hydroxysteroid Dehydrogenases↗