Search PubMed⌕ Search

Biomedical subjects

R Nakano

Publications and source records attributed to R Nakano.

At least 145 records · Page 8Linked to original sources
PubMed1993

Immunohistochemical localization of inhibin subunits in polycystic ovary.

The immunohistochemical localization of the alpha-, beta A-, and beta B-subunits of inhibin was examined in polycystic ovary (PCO). The granulosa cells in multicystic follicles in the PCO exhibited negative immunostaining for alpha-subunit and positive staining for beta A- and beta B-subunits. In contrast, the hyperplastic thecal cells exhibited distinct positive staining for alpha-, beta A-, and beta B-subunits. The luteinized stromal cells (stromal hyperthecosis) also exhibited positive staining for each inhibin subunit. The granulosa cells in the tertiary follicle exhibited negative staining for alpha-subunit and positive staining for beta A- and beta B-subunits. No staining for each inhibin subunit was observed in the thecal layer in the tertiary follicle. The present findings suggest that immunoreactive inhibin alpha-, beta A-, and beta B-subunits are present in hyperplastic thecal and stromal cells in PCO, and that granulosa cells in the follicular cyst of PCO might not produce inhibin, in contrast to the normal ovary.

Adult↗
PubMed1993

Opposite effects of basic fibroblast growth factor on gonadotropin-stimulated steroidogenesis in rat granulosa cells.

In the present study, we examined the effect of basic fibroblast growth factor (bFGF) on gonadotropin-dependent estradiol and progesterone production in cultured rat immature and FSH-primed granulosa cells. Treatment with bFGF alone did not affect the biosynthesis of estradiol and progesterone in immature and FSH-primed granulosa cells. Basic FGF significantly inhibited FSH-induced estradiol and progesterone production in both immature and FSH-primed granulosa cells. In contrast, bFGF exerted a significant stimulatory effect on LH-induced estradiol and progesterone production in FSH-primed granulosa cells. Our finding that bFGF exerts opposite effects on gonadotropin-dependent steroidogenesis suggests that bFGF may play important paracrine and/or autocrine roles in the process of follicular development, ovulation, and subsequent luteinization.

Animals↗
PubMed1993

Biological activity of partially purified low molecular weight luteinizing hormone binding inhibitor in porcine follicular fluids.

We performed partial purification of low molecular weight luteinizing hormone binding inhibitor from porcine follicular fluids and examined its biological activities. Following ultrafiltration, gel filtration and anion exchange of the pooled porcine follicular fluids, low molecular weight fractions (500-10,000 MW) inhibited [125I]hLH binding to porcine granulosa cells in a dose-dependent manner. The binding inhibition kinetics study revealed that the luteinizing hormone binding inhibitor may indicate a non-competitive inhibition with [125I]hLH binding. In vitro bioassay using adult mouse testicular interstitial cells revealed that the partially purified luteinizing hormone binding inhibitor reduced ovine LH-stimulated testosterone and cAMP production in a dose-dependent manner, whereas the luteinizing hormone binding inhibitor did not affect basal production of testosterone and cAMP. The inhibitory activity was heat stable and did not disappear with activated charcoal adsorption. The results of the present study suggest that the luteinizing hormone binding inhibitor may play an important role as an ovarian non-steroidal regulator modulating the receptor binding of LH and LH-mediated steroidogenesis.

Animals↗
PubMed1993

Immunohistochemical localization of pituitary gonadotropins and estrogen in human postmenopausal ovaries.

Immunohistochemical localization of pituitary gonadotropins (FSH, LH) and estrogen was investigated in 17 ovaries from ten postmenopausal women. Positive immunostaining for 17 beta-estradiol was demonstrated in the cortical stroma of 14 postmenopausal ovaries. Positive immunostaining for FSH was localized in the cortical stroma of 12 postmenopausal ovaries, and positive immunostaining for LH was also localized in 12 ovaries. Immunohistochemical localization for pituitary gonadotropins (FSH and/or LH) and 17 beta-estradiol was identified in the same hypertrophic cortical stroma of 13 postmenopausal ovaries. The ultrastructural study suggested steroidogenic activity in the cortical stromal cells of the postmenopausal ovary. In addition, peripheral and ovarian venous concentrations of 17 beta-estradiol were measured in 13 postmenopausal subjects, and significant concentration gradient for serum 17 beta-estradiol was noted. The ovarian/peripheral concentration gradient for 17 beta-estradiol had a tendency to be higher in the subjects with positive immunostaining for 17 beta-estradiol compared with that in the subjects with negative immunostaining. The present results suggest that the human ovary secretes estrogen in response to pituitary gonadotropins even after the menopause.

Aged↗
PubMed1993

Immunohistochemical localization of inhibin-activin subunits in hydatidiform mole and invasive mole.

OBJECTIVE: To examine the cellular localization of each inhibin subunit in hydatidiform mole and invasive mole. METHODS: Tissues were collected and fixed in Bouin's solution and studied with the immunohistochemical technique avidin-biotin-peroxidase complex. RESULTS: In the villous trophoblasts of hydatidiform mole and invasive mole, distinct immunostaining for inhibin alpha-subunit was observed in proliferative syncytiotrophoblasts, but not in the cytotrophoblasts. Positive immunostaining for beta A- and beta B-subunits was observed in both syncytiotrophoblasts and cytotrophoblasts. In extravillous trophoblasts of the invasive mole, staining for beta A- and beta B-subunits was observed, whereas staining for alpha-subunit was not detected. CONCLUSION: Inhibin-activin subunits may be produced in the trophoblasts of hydatidiform mole and invasive mole, and inhibin and activin may play a role in trophoblastic proliferation and invasion.

Female↗
PubMed1993

[Lysosome disease--Sandhoff disease].

Lysosomal beta-hexosaminidase occurs as two major isozymes hexosaminidase A and B. The alpha subunit is encoded by the HEXA gene and the subunit by HEXB gene. Defects in the beta subunit lead to Sandhoff disease. Patients with the defect lack the activity or formation of both hexosaminidase A and B. The disorders are classified according to the age of onset, as infantile, juvenile and adult form. Recent molecular genetic analysis has revealed a 50 kb deletion, 16 kb Alu type deletion, and compound heterozygous with other mutations. In the juvenile or adult type of the disease, point mutation of the HEXB gene, creating a new 3' splice acceptor site. The correlation of the clinical phenotype and the gene abnormalities is discussed.

Adolescent↗
PubMed1992

Epidermal growth factor binding sites in porcine granulosa cells and their regulation by follicle-stimulating hormone.

Epidermal growth factor (EGF) modulates ovarian function, including folliculogenesis and steroidogenesis. We investigated the localization of EGF binding sites in the porcine ovary, and the effect of FSH on EGF binding to cultured granulosa cells. Autoradiographic study demonstrated that the binding sites for 125I-labeled mouse EGF in the porcine ovary were present in the granulosa and luteal cells, but not in the thecal cells. Porcine granulosa cells were collected by the needle aspiration method from small (1-2 mm) and medium-sized (3-5 mm) follicles. Scatchard analysis showed that a single class of the specific binding sites for EGF was present in the granulosa cells. The number of binding sites and the apparent dissociation constant were 5,540 binding sites/cell and 0.23 nM (medium-sized follicle), respectively. No significant difference was observed between small and medium-sized follicles. Granulosa cells were cultured for 48 h at 37 degrees C in medium alone or with increasing doses of ovine FSH (1-100 ng/ml). FSH treatment significantly increased EGF binding in a dose-dependent manner. In conclusion, it is suggested that the specific high affinity, low capacity binding sites for EGF are present in porcine granulosa cells, and that they are up-regulated by FSH.

Animals↗
PubMed1992

Effects of estrogen, pituitary gonadotropins and prolactin on immunohistochemical localization of inhibin subunits in the ovary of hypophysectomized female rats.

Effects of estrogen, pituitary gonadotropins and prolactin on immunohistochemical localization of alpha- and beta A-subunits in the ovaries of hypophysectomized female rats were investigated. Hypophysectomy resulted in disappearance of immunoreactive inhibin subunits in the ovary. Administration of DES, FSH and LH to hypophysectomized rats provoked growth of follicles, and resulted in positive immunostaining for inhibin subunits in the granulosa cells. In contrast to follicle-stimulating hormone (FSH) and luteinizing hormone (LH), prolactin administration failed to demonstrate positive staining for inhibin subunits in the ovary. The present in vivo results suggest that several hormones which are known to stimulate granulosa cell growth and maturation, such as estrogen, FSH and LH, enhance inhibin subunit production by the ovary. The morphologic aspect of inhibin subunit production by the ovary in response to several hormones has been demonstrated in the present study.

Animals↗
PubMed1992

Gonadotropin receptors in human ovarian follicles and corpora lutea throughout the menstrual cycle.

To study changes in the binding of gonadotropins to human follicles and corpora lutea, we have examined the binding of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the human ovary throughout the menstrual cycle, by both quantitative binding assays and surface binding autoradiography. The specific high-affinity low-capacity receptors for hLH were demonstrated in both human follicles and corpora lutea. Binding of 125I-hFSH was identified in the granulosa cells, but not in the thecal cells of the preantral and antral follicles at various stages of follicular development. The binding of 125I-hLH to the thecal cells increased during follicular development, and a dramatic increase was preferentially observed in the granulosa cells of the preovulatory follicles. In the corpora lutea, the binding of 125I-hLH increased from the early luteal phase to the midluteal phase and decreased towards the late luteal phase. The results of the present study suggest that changes in the binding of gonadotropins in the ovarian target cells during the menstrual cycle might play an important role in the regulation of follicular and luteal function.

Autoradiography↗
PubMed1992

Follicle-stimulating hormone induces functional receptors for basic fibroblast growth factor in rat granulosa cells.

In the present study we examined the existence of receptors for basic fibroblast growth factor (bFGF) and its regulation in rat granulosa cells. The binding of labeled bFGF to rat granulosa cells was dose-dependently displaced by unlabeled bFGF, but not other growth factors. FSH induced a dose-dependent increase in specific binding for bFGF to cultured rat granulosa cells. FSH treatment did not change the binding affinity (Kd, 2.8-3.0 x 10(-10) M) of the bFGF receptor, but increased the total number of bFGF-binding sites, whereas treatment with several steroid hormones had no effect on the specific binding of bFGF. Since cycloheximide, a protein synthesis inhibitor, inhibited the increase in bFGF binding induced by FSH, it is suggested that protein synthesis might be involved in the FSH stimulation of bFGF receptor induction. Furthermore, bFGF stimulated tissue plasminogen activator activity in a dose-dependent manner, and FSH-primed granulosa cells were more responsive to bFGF action, with a decrease in the ED50 from 5.0 to 1.5 ng/ml. The antibody against human bFGF neutralized the stimulatory effect of bFGF on tissue plasminogen activator secretion. The present study suggests that FSH induces functional receptors for bFGF in granulosa cells and that bFGF may play a role in the process of differentiation under the influence of FSH.

Animals↗
PubMed1992

Immunohistochemical localization of inhibin/activin subunits in human ovarian follicles during the menstrual cycle.

The immunohistochemical localization of the alpha-, beta A-, and beta B-subunits of inhibin was examined in human follicles during follicular growth. Immunoreactive staining with antisera against the alpha-, beta B-subunits was observed in follicular granulosa cells, whereas no staining for each inhibin subunit was observed in thecal or interstitial cells. In the preantral and small antral follicles, the granulosa cells exhibited positive immunoreactive staining with antisera against beta A- and beta B-subunits and negative immunostaining with antiserum against alpha-subunit. In medium-sized healthy antral follicles obtained during the midfollicular phase, positive immunostaining with antisera against alpha-, beta B-subunits was detected in the granulosa cells. In contrast, immunostaining for alpha-, beta A-, and beta B-subunits was not detected in the granulosa cells of similarly sized atretic follicles. The granulosa cells of preovulatory follicles revealed enhanced positive staining for the three inhibin subunits. The present findings suggest that immunoreactive inhibin subunits are present in the follicular granulosa cells during the menstrual cycle, and that the localization and intensity of immunostaining for each inhibin subunit might change during follicular development and maturation.

Activins↗
PubMed1992

Immunohistochemical localization of inhibin/activin subunits in human placenta.

OBJECTIVE: To examine the cellular localization of each inhibin subunit in human placenta throughout pregnancy. METHOD: Placental tissues were collected and fixed in Bouin's solution, and studied with the immunohistochemical technique avidin-biotin-peroxidase complex. RESULTS: There was immunohistochemical staining with antisera against each inhibin subunit in the syncytiotrophoblast, but not in the cytotrophoblast. In the first-trimester placenta, positive immunostaining for alpha- and beta A-subunits was clearly observed in the syncytial layer of villi, whereas staining for beta B-subunit was faint. In the second-trimester placenta, the relative intensities of staining for alpha- and beta A-subunits were similar to those in the first-trimester placenta, and enhanced positive immunostaining with beta B-subunit antiserum was observed. The relative amount of immunostainable alpha-subunit declined within the syncytiotrophoblast of the third-trimester placenta, whereas levels of immunostainable beta-subunits were unchanged. CONCLUSIONS: Inhibin subunits may be produced in the syncytiotrophoblast throughout pregnancy, and activin as well as inhibin may be synthesized in the syncytiotrophoblast of the term placenta.

Activins↗
PubMed1991

Immunohistochemical localization of myelin-associated glycoprotein isoforms during the development in the mouse brain.

The developmental changes in localization of myelin-associated glycoprotein (MAG) isoforms in the mouse brain were demonstrated by an immunohistochemical method using antisera specific to two MAG isoforms. The antiserum to the large isoform of MAG (L-MAG) stained the myelin sheaths and the cytoplasm of oligodendroglia in the active myelinating stage in the mouse central nervous system. However, the antiserum to the small isoform of MAG (S-MAG) stained only myelin sheaths in the adult stage. These findings suggest that L-MAG plays an important role in active myelination.

Animals↗
PubMed1991

Expression of the large myelin-associated glycoprotein isoform during the development in the mouse peripheral nervous system.

The developmental maximum expression of the large myelin-associated glycoprotein isoform (L-MAG) protein prior to that of the small myelin-associated glycoprotein isoform (S-MAG) in both the central and peripheral nervous systems (CNS, PNS) in mice was shown by immunoblotting techniques using specific antibodies to the L-MAG protein and the S-MAG protein. Both the L-MAG protein and the S-MAG protein were expressed earlier in the PNS than in the CNS, which reflects earlier myelination in the PNS. The peak of the L-MAG protein concentration was 8 days in the sciatic nerve and 15 days in the brainstem. The concentration of the S-MAG protein in the sciatic nerve reached a peak at 15 days, whereas in the brainstem it increased rapidly between 15 and 20 days and gradually thereafter. Thus, the preceding maximum expression of the L-MAG during active myelination in the PNS demonstrated here as well as in the CNS strongly suggests an important role for L-MAG in myelin formation.

Aging↗
PubMed1991

Overproduction of adenovirus DNA polymerase and preterminal protein in HeLa cells.

Adenovirus (Ad) DNA polymerase (AdPol) and the preterminal protein (pTP) form a complex that is involved in the in vitro initiation of Ad DNA replication. Recombinant vaccinia viruses (vv) were constructed in which the genes encoding AdPol and pTP were cloned into a vaccinia/T7 hybrid expression-based vector downstream from the T7 promoter (pT7)/encephalomyocarditis virus (EMCV) 5'-untranslated region (UTR). HeLa cells infected with the recombinant vv-AdPol or vv-pTP or a mixture of both, together with the vv expressing T7 RNA polymerase produced significant levels of pTP and AdPol which were biologically active in the in vitro initiation of Ad DNA replication. These amounts of pTP and AdPol were only about two-fold less than the levels produced in insect cells infected with the recombinant baculovirus constructs expressing AdPol and pTP.

Adenoviruses, Human↗