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Biomedical subjects

Y Ibuki

Publications and source records attributed to Y Ibuki.

At least 73 records · Page 4Linked to original sources
PubMed1997

Factors affecting the development of oocytes and embryos in IVF-ET.

In our study in hMG/hCG protocol, there is correlation between basal FSH level and number of oocyte retrieved (Rs = -0.4334, p = 0.039). FSH was not useful in predicting poor responders in an in vitro fertilization program where pituitary desensitization is routinely used. There is correlation between day 2, day 3 serum immunoactive inhibin level and number of follicle developed with hMG alone, or with hMG in conjunction with pituitary desensitization using a buserelin intranasal spray. The patients were divided by relationship between E2 peak and inhibin peak. The most of oocytes retrieved, oocytes fertilized and embryos cleaved were obtained when hCG was injected on the E2 peak day following the inhibin peak day. Inhibin concentration in aspirated follicular fluids was low and estradiol concentration was high in pregnant group. There is correlation between acceleration index of inhibin and number of oocyte retrieved in both protocols. Inhibin levels were significantly lower (P < 0.05) in women older than 36 years of age, although estradiol responses were not so influenced by age. These data suggest that: (1) In the early follicular phase, inhibin may be a valid index to predict ensuing follicular growth and follicular development. (2) The serum inhibin responses to maximal ovarian stimulation may be a sensitive and early index of declining ovarian function with advancing age. (3) Inhibin is an important factor for the diagnosis of pregnancy outcome.

Adult↗
PubMed1996

Regulation of midkine messenger ribonucleic acid levels in cultured rat granulosa cells.

To investigate the regulation of ovarian midkine (MK) production at the mRNA level, we evaluated changes in MK mRNA in cultured granulosa cells. The level of MK mRNA increased in a time-dependent manner in the presence of FSH or retinoic acid (RA). FSH increased MK mRNA levels in a dose-dependent manner to a maximum of about 2-fold increase. The stimulatory effects of FSH were mimicked by 8-Br-cAMP. RA increased MK mRNA levels in a dose dependent manner to a maximum of about 2 fold increase at a concentration of 0.3 microM. These results show that granulosa cells produce MK mRNA under the independent control of FSH and RA. The coexistence of FSH and RA in this culture exerted no additive effect on the induction of MK mRNA. Analysis of FSH receptor mRNA induction by both reagents revealed that FSH stimulated expression of the FSH receptor while RA had an inhibitory effect on FSH receptor induction regardless of the presence of FSH. These data show that RA increases MK mRNA, and decreases FSH receptor expression, by a pathway independent of cAMP.

Animals↗
PubMed1996

Quantification of estrogen receptor messenger RNA by quantitative polymerase chain reaction using internal standard fragment.

A simple and reliable polymerase chain reaction-based method for quantifying human and rat estrogen receptor (ER)-mRNA is described. This method involves co-amplification of cDNA transcribed from sample RNA with an internal standard to reduce tube to tube amplification variations. Human and rat internal standards were synthesized by insertion of a DNA fragment near the midportion of human and rat target ER cDNA molecules. After co-amplification, both products of target ER cDNA and internal standard were separated on agarose gel by electrophoresis and transferred onto a membrane filter. The radioactivity hybridized with 32P-labeled ER cDNA was counted. The ER mRNA content was calculated by linear regression analysis after obtaining a logarithm of ratios between the sample and the internal standard radioactivity. The coefficient of variation of this assay was 18.8%. An absolute amount of ER mRNA in less than 10(4) cultured cells could be measured.

Animals↗
PubMed1996

Effect of estriol on bone loss in postmenopausal Japanese women: a multicenter prospective open study.

OBJECTIVES: To assess the effects of oral estriol on the bone mineral density (BMD) and bone metabolism in postmenopausal women. METHODS: Seventy-five natural postmenopausal women with a BMD of more than 10% below the peak bone density were treated for 50 weeks with 2 mg/day estriol (E3) cyclically and 0.8 g/day of calcium lactate continuously. BMDs at L2-L4 were measured by dual energy X-ray absorptiometry (DXA). RESULTS: The BMD increased 1.79% (p < 0.01 vs. pretreatment) after 50 weeks, accompanied with decrease of biochemical markers of bone turnover. With regard to climacteric symptoms, Kupperman's menopausal index improved (p < 0.01 vs. pretreatment) after 5 weeks of treatment. As to the incidence of adverse events genital bleeding was observed in only 8.0% of the subjects. Endometrial histology and cytology showed neither abnormalities nor hyperplasia during and after the treatment. CONCLUSIONS: Estriol prevented postmenopausal bone loss and improved climacteric symptoms effectively with low incidence of genital bleeding.

Bone Density↗
PubMed1996

Regulation of follicle-stimulating hormone receptor.

The acquisition of follicle-stimulating hormone (FSH) receptors during folliculogenesis is believed to be a key event in follicle development. We have examined the effects of FSH and activin on FSH receptor mRNA in cultured rat granulosa cells. Treatment of granulosa cells with FSH resulted in transient suppression of the FSH receptor mRNA levels 2-6 h after treatment, with subsequent recovery at 24 h. We could not detect a similar effect on FSH receptor mRNA by 8-bromoadenosine 3,5-cyclic monophosphate, which continuously stimulated FSH receptor mRNA over a similar time course. On the other hand, stimulation of the protein kinase C (PKC) pathway with phorbol myristate acetate mimicked the time course of the effects of FSH on the levels of FSH receptor mRNA. Taken together, these results suggest that the cAMP cascade may increase the mRNA levels of FSH receptor and, at the same time, the other cascade, PKC, may decrease FSH receptor mRNA levels. To further investigate the role of activin in the regulation of granulosa cell function, we studied the effect of activin on FSH receptor mRNA levels. Compared to the control, treatment with activin (100 ng/ml) increased FSH receptor mRNA in a time-dependent manner with a maximum circa 4-fold increase at 24 h. Treatment of granulosa cells with activin (20-300 ng/ml) for 24 h increased FSH receptor mRNA in a dose-dependent manner to a maximum circa 4-fold increase at concentrations of 100-300 ng/ml. Although follistatin alone had no detectable effect on FSH receptor mRNA levels, combination of follistatin (0-200 ng/ml) with activin (100 ng/ml) caused a significant reduction in the levels of activin-induced FSH receptor mRNA in a dose-dependent manner.

Activins↗
PubMed1996

Calcium supplements increase bone mineral density in women with low serum calcium levels during long-term estrogen therapy.

In order to clarify whether the long-term effect of estrogen on bone mineral density (BMD) is reinforced by low dose calcium supplements, 600-800 mg of calcium lactate was administered to postmenopausal or oophorectomized women who had been undergoing unopposed estrogen therapy for at least 2 years and whose serum calcium level was suppressed to below the normal range. To patients whose serum calcium levels had been within the normal range, the same dose of estrogen alone was continued. Changes in lumbar spine BMD before and after calcium supplementation was measured by dual-energy X-ray absorptiometry. Lumbar spine BMD decreased by -0.37% for 2 years in women treated with estrogen alone, while that of women treated with estrogen and calcium increased by 2.78% (P = 0.003). These results indicate that low dose calcium supplements potentiate the effect of estrogen in women with decreased serum calcium during long-term hormone replacement therapy.

Absorptiometry, Photon↗
PubMed1996

Recombinant human growth hormone acts on intermediate-sized follicles and rescues growing follicles from atresia.

In order to clarify the role of ovarian function, recombinant human GH (rhGH) was administered to adult spontaneous dwarf rats (SDR) for 14 days. The SDR were sacrificed on the day of estrus and the effects of rhGH on ovarian weight, follicular population and the viability estimated by 5-bromodeoxyuridine (BrdU) incorporation, were studied. RhGH administration caused a significant gain in body weight of the SDR, and the ovarian weight of the GH-injected SDR showed a significant increase in comparison with saline injected SDR. The total population of follicles was significantly greater in the GH-treated group than in the control, and the difference was attributed to the increase in the number of large follicles more than 500 micrograms. Total uptake of BrdU into granulosa cells was significantly higher in GH-treated rats than in the control, and, in particular, the intermediate-sized follicles (300-500 micrograms) of the GH-treated rats showed signs of high incorporation of BrdU. These results suggest that hGH acts on intermediate follicles, stimulates their viability and increases the number of growing follicles.

Animals↗
PubMed1996

[Reversal of portal-systemic encephalopathy by shunt-preserving disconnection of portal and systemic circulation].

Obliteration of portal-systemic shunts surgically or by interventional radiological techniques is fairly effective in reversing intractable portal-systemic encephalopathy (PSE), but is often associated with ascites accumulation and/or formation of esophageal varices. This study reports four patients with incapacitating PSE who were treated by interventional radiological techniques via percutaneous transhepatic route. One case had the shunt embolized directly. In the other three the blockage was placed on the proximal part of the splenic vein, whereby disconnecting the mesenteric-portal blood flow from the systemic circulation while preserving the shunt. The patient of shunt closure showed transient correction of encephalopathy, but developed massive ascites and esophageal varices, encephalopathy recurred, resulting in death from hepatic failure two months after the procedure. In the cases of shunt-preserving disconnection of portal and systemic circulation (SPDPS) immediate and permanent clearing of encephalopathy was achieved without manifestation of ascites or esophageal varices during the follow-up period of 10 to 31 months. The difference of portal pressure between before and after the procedure was 18 mmHg in the shunt-closed patient and 3 mmHg in SPDPS group. We conclude from this limited experience that SPDPS can be an effective and safe method in treating PSE in adequately selected patients.

Aged↗
PubMed1995

Regulation and localization of midkine in rat ovary.

In a previous experiment, it was shown that midkine (MK) was quite abundant in the follicular fluid; the concentration of MK in bovine follicular fluid was estimated to be 125 micrograms/l. To investigate the regulation of MK production in the ovary, we examined the effect of pregnant mare's serum gonadotropin (PMSG) and PMSG-hCG treatment on the expression of MK in rat ovary. The mRNA of midkine (MK) was increased by PMSG injection and decreased by PMSG and hCG injection; the profile of change of mRNA of MK was similar to that of FSH receptor. Using in situ hybridization, we observed that the MK mRNA localized to granulosa cells. These results suggest that the granulosa cells produce MK under the control of gonadotropin.

Animals↗
PubMed1995

Regulation of follistatin messenger ribonucleic acid in cultured rat granulosa cells.

The regulation of the follistatin mRNA by hormones and endocrine manipulations was examined in granulosa cell cultures. The follistatin mRNA accumulation was stimulated in a dose-dependent manner by follicle-stimulating hormone (FSH) with a maximal response twice as great as in control cultures at a dose of 100 ng/ml FSH. The time course of the FSH effect on follistatin mRNA had a biphasic effect in which FSH increased follistatin mRNA within 2 h, and subsequently reduced it to below the control level. 8-Br-8 brom-adenosine 3,5-cyclic monophosphate (cAMP) (2 mM) and phorbol 12-myristate 13-acetate (PMA) (10 nm) induced a time-dependent increase in follistatin mRNA levels, with the maximal response at 6 h and 2 h, respectively. Co-treatment of the granulosa cells with cAMP and PMA demonstrated that 0.2 mM of 8-Br-cAMP suppressed the follistatin mRNA of the control and the samples with a small amount of PMA in the granulosa cells. Follistatin expression is therefore regulated by protein kinase A and protein kinase C pathways in rat granulosa cells. A more dramatic stimulation of follistatin mRNA was observed when this culture was treated with activin, and follistatin also blocked the effect of activin on the follistatin mRNA.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1995

Regulation of follicle-stimulating hormone receptor messenger ribonucleic acid levels in cultured rat granulosa cells.

The acquisition of follicle-stimulating hormone (FSH) receptors during follicogenesis is believed to be a key event in the subsequent development of the follicle. We have examined the effect of FSH on FSH receptor mRNA in cultured rat granulosa cells by means of FSH receptor cRNA probe. Northern blot analysis indicated the existence of two predominant FSH receptor mRNA transcripts of approximately 5.5 and 2.4 kb in total RNA prepared from rat granulosa cells. Treatment of granulosa cell culture with FSH resulted in tentative suppression of FSH receptor mRNA level 2-6 h after treatment, with subsequent recovery at 24 h. Culture of granulosa cells for 6 h in the presence of increasing concentration of FSH resulted in a dose-dependent decrease in FSH receptor mRNA with a maximal suppression about 50% of control observed in response to 100 ng/ml FSH. We could not detect a similar effect on FSH receptor mRNA by 8-brom-adenosine 3,5-cyclic monophosphate (8-Br-cAMP; 0.2 mM) which showed continuous stimulation on FSH receptor mRNA during a similar time course. In this system, therefore, this transient down-regulation of FSH mRNA was not mediated by the cAMP pathway. Since the inhibitory effect of follistatin on activin-induced FSH binding to rat granulosa cells had been investigated, we studied the action of follistatin on the levels of activin-induced FSH receptor mRNA in rat granulosa cell culture.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1995

Type II and type IIB activin receptors in human placenta.

The expression of type II activin receptor(ActRII) and type IIB activin receptor(ActRIIB) messenger RNA(mRNA) in different stages of development of the human placenta was examined by Northern blot analysis. In our experiments, the first trimester placenta showed the highest levels of ActRIIB expression and human placenta from different stages expressed both type II and IIB activin receptor mRNAs. These observations support the hypothesis that activin might act as a paracrine/autocrine factor in human placenta and activin might have stage specific functions through the different types of receptors.

Activin Receptors↗
PubMed1995

Application of Chinese hamster ovary cells transfected with the recombinant human follicle-stimulating hormone (FSH) receptor for measurement of serum FSH.

OBJECTIVES: To evaluate the activity of the serum FSH bioactivity in patients with premature ovarian failure (POF). DESIGN: Prospective study. SETTING: Infertility and gynecology outpatient clinics at the Gunma University School of Medicine, Gunma, Japan. PATIENTS: Twelve women, aged 27 to 39 years, with POF and nine postmenopausal women. INTERVENTIONS: Serum samples obtained from postmenopausal women and POF patients. The immunoglobulin (Ig)G fractions of some sera from POF patients were prepared by 20% polyethylene glycol. MAIN OUTCOME MEASURES: Serum samples were measured simultaneously by the bioassay system and immunoradiometric assay (IRMA). RESULTS: The bioassay values correlated with those obtained by IRMA, and the correlation coefficient and the slope of the regression lines calculated from nine pairs of assay values from the postmenopausal women were 0.867 and 1.10, respectively. The mean of the biologic:immunologic ratios of sera from postmenopausal women and POF patients were 1.44 and 1.25, respectively. CONCLUSIONS: The IgG fractions of some sera from POF patients showed stimulatory or inhibitory effect on cyclic adenosine 3':5' monophosphate production compared with that from postmenopausal women. These results may reflect the more complex pathophysiological states of the patients with POF.

Adult↗
PubMed1995

A role of protein kinase C in the alteration of renal glucose-6-phosphatase activity caused by fluoride.

In this study, protein kinase C was demonstrated to operate as a down-regulator of glucose-6-phosphatase in the kidney, at least. Renal glucose-6-phosphatase activity reached a maximum level in 3 h after the administration of fluoride to rats. The incremental increase of renal glucose-6-phosphatase activity caused by fluoride administration was markedly amplified by the administration of staurosporine (66 micrograms/kg, i.p.), which has inhibitory activity against protein kinase C, or by the administration of H-7 (5 mumol/kg, i.p.), a specific and strong inhibitor of protein kinase C. Interestingly, the finding indicated that protein kinase C operates as a down regulator of renal glucose-6-phosphatase activity. The finding was reconfirmed by the result that fluoride-stimulated glucose-6-phosphatase activity was further enhanced by treatment with calphostin C (200 nmol/kg, i.p.), a specific and strong inhibitor of protein kinase C, but the change was small. Moreover, calmodulin was indicated as being possibly concerned with the down regulation of renal glucose-6-phosphatase activity by using W-7 (5 mumol/kg, i.p.), a calmodulin specific inhibitor.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Augmentation of NO production and cytolytic activity of M phi obtained from mice irradiated with a low dose of gamma-rays.

The activation of macrophages (M phi) by low-dose irradiation (4cGy) was examined. The irradiated M phi were obtained from mice exposed to a low dose of gamma-rays. The addition of excess irradiated M phi suppressed more the concanavalin A-induced proliferation of splenocytes than that of unirradiated M phi. This was attributed to large nitric oxide (NO) production from irradiated M phi. In addition, low-dose irradiation augmented NO production and glucose consumption in M phi treated with interferon-gamma alone or interferon-gamma/lipopolysaccharide. Furthermore, low-dose-irradiated M phi showed a higher cytolytic activity against P-815 mastocytoma cells than unirradiated M phi, indicating that the NO production was involved in the activity. On the other hand, the M phi irradiated with a low dose in vitro did not enhance the NO production. These findings suggest that whole-body irradiation with a low dose of gamma-rays activates M phi indirectly and consequently enhances NO production from M phi, by which the self-defense systems such as the tumoricidal activity will be augmented.

Animals↗
PubMed1995

Effects of exercise and amenorrhea on bone mineral density in teenage runners.

In order to elucidate whether exercise and calcium intake can offset bone loss due to hypoestrogenemia in teenage girls, the lumbar and femoral bone mineral density (BMD) in elite amenorrheic runners (group 1 (n = 8)) was compared with those in eumenorrheic athletes (group 2 (n = 15)) and two groups of eumenorrheic non-athletic subjects, group 3 (n = 14), and group 4 (n = 15). BMD was measured by dual energy x-ray absorptiometry. The subjects in group 1 lived in the dormitory, and their calcium intake was controlled to > 1400 mg/day. The subjects in groups 1, 2 and 3 were age matched (16-17 years old), but the body weight of those in group 2 was significantly greater than that of others. The subjects in groups 1, 3 and 4 were weight matched, but group 4 subjects were older by 5 years (21.0 +/- 0.2 years old). The lumbar BMD of group 1 was 1.0460 +/- 0.0259, which was not statistically different from those in the other groups, while the femoral BMD of group 1 was significantly higher than those of groups 3 and 4 at trochanter. The lumbar and femoral BMD of group 2 was significantly higher than in groups 3 and 4, but was not statistically different from group 1. There were no significant differences in serum parathyroid hormone levels, but osteocalcin and calcitonin levels of group 1 were significantly lower than those of groups 2 and 3, and groups 2, 3 and 4, respectively, suggesting that the rate of bone formation is suppressed in amenorrheic runners.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Interaction between activin A and cAMP in the induction of FSH receptor in cultured rat granulosa cells.

The acquisition of FSH receptor during preantral folliculogenesis is believed to be a key step in the subsequent development of follicles. We examined the interaction between activin and cAMP in FSH receptor induction in rat granulosa cells by measuring 125I-FSH binding and FSH receptor mRNA. In the 125I-FSH binding study, 0.2 mM 8-Br-cAMP and 1 microM forskolin were maximally effective in FSH receptor induction (169 and 220% respectively of control), while higher concentrations gave attenuated responses. It appears that cAMP has ambivalent effects on FSH receptor induction depending on the concentration and length of exposure. Activin alone dramatically increased the number of FSH receptors (314% of control). Moreover, synergistic effects of activin and 8-Br-cAMP or forskolin were observed on FSH receptor induction: a combination of activin (80 ng/ml) and low doses of 8-Br-cAMP (0.2 mM) or forskolin (1 microM) was most effective (160 or 140% of that induced by activin alone) and receptor levels reached a maximum at 24 h. These levels than markedly decreased after 72 h of incubation. Northern blot analysis revealed that the combination of activin (80 ng/ml) and 8-Br-cAMP (0.2 mM) or forskolin (1 microM) increased FSH receptor mRNA to about 140% of that induced by activin alone. These results indicate that activin and cAMP induced FSH receptor synergistically. However, activin did not enhance the production of cAMP induced by forskolin. In addition, a protein kinase A inhibitor (H89) (2 microM), which inhibited the effects of forskolin, had no effect on the action of activin.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗