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M Taga

Publications and source records attributed to M Taga.

At least 55 records · Page 3Linked to original sources
PubMed1996

Immunohistological localization of tenascin in the human endometrium.

Tenascin (TN) is an extracellular matrix glycoprotein that seems to be involved in embryogenesis, carcinogenesis and wound healing. In order to clarify the biological significance of TN in the human endometrium, we investigated its expression in the normal as well as in the hyperplastic and neoplastic human endometrium, using immunohistochemistry. We also investigated the coexistence of TN with proliferating cell nuclear antigen (PCNA), a marker of cell proliferation, in endometrial carcinoma to further assess the involvement of TN in regulating cell proliferation. TN expression was observed in the stroma surrounding the endometrial gland in the proliferative phase, whereas it could not be found in the secretory phase. The localization of TN and PCNA coincided frequently, as the stromal portion where the expression of TN was observed always showed positive for PCNA. These results suggest that TN is involved in cell proliferation and carcinogenesis in the human endometrium.

Cell Division↗
PubMed1996

Changes in bone mass as determined by ultrasound and biochemical markers of bone turnover during pregnancy and puerperium: a longitudinal study.

In a longitudinal study, we analyzed the speed of sound (SOS) and broadband ultrasound attenuation (BUA) of the os calcis as an index of bone mineral density (BMD) to define the effects of pregnancy and lactation on bone metabolism. We used an ultrasound bone densitometer and measured 6 biochemical markers of bone turnover in 18 healthy women throughout pregnancy and puerperium. The measurement of SOS and BUA by such an ultrasound device was clinically advantageous; not only is it radiation-free technology, but it also correlates highly with BMD measured by conventional X-ray bone densitometry. While a significant decrease in SOS was found in the 3rd trimester of pregnancy as compared with the early stage of pregnancy, there was no difference in both SOS and BUA between the breast-feeding women and the principally formula-feeding women during a 6-month period of puerperium. The analysis of biochemical markers revealed that both bone formation and bone resorption were elevated in the 3rd trimester of pregnancy as well as during puerperium, and that the breast-feeding women had significantly higher bone metabolism than the principally formula-feeding women. These results indicate that bone mass decreases as bone turnover itself is enhanced during pregnancy, while lactation does not substantially affect bone mass during at least 6 months of puerperium, although bone turnover is active.

Adult↗
PubMed1996

Continuous stimulation of gonadotropin-releasing hormone (GnRH) receptors by GnRH agonist decreases pituitary GnRH receptor messenger ribonucleic acid concentration in immature female rats.

Although it is well recognized that continuous administration of gonadotropin-releasing hormone agonist (GnRHa) induces pituitary desensitization, the precise molecular mechanism of this phenomenon is still unclear. To test the hypothesis that pituitary gonadotroph desensitization is mediated by a change in GnRH receptor (GnRH-R) gene expression, the GnRH-R mRNA concentration was analyzed in immature female rats during GnRHa treatment. Northern blot hybridization was used to determine the GnRH-R mRNA concentration several times after an injection of TAP-144-SR, a slow releasing GnRHa. The GnRH-R mRNA readings were 92.7 +/- 9.5%, 49.9 +/- 5.0%, 35.7 +/- 2.3% and 73.8 +/- 5.7% (Mean +/- SD) compared to each control value at 1, 2, 4 and 8 weeks, respectively, after a single injection of 0.94 mg TAP-144 SR. These changes in GnRH-R mRNA coincided with the changes in gonadotropin secretion and LH-beta mRNA in response to GnRH in the results of our previous report. The present results indicate that the reduction of the number of pituitary GnRH-R sites induced by continuous stimulation with GnRHa is regulated at a transcriptional level.

Animals↗
PubMed1996

Reduction of bone mineral density by gonadotropin-releasing hormone agonist, nafarelin, is not completely reversible at 6 months after the cessation of administration.

STUDY OBJECTIVE: To determine the reversibility of bone mineral density after the cessation of GnRH agonist treatment for endometriosis. DESIGN: Longitudinal trial with 6-month treatment period and 6-month follow-up. PATIENTS: 28 Japanese premenopausal women with endometriosis. INTERVENTIONS: Daily dose of 400 micrograms nafarelin was administered for 6 months. MEASUREMENT AND MAIN RESULTS: The spine bone mineral density was measured by dual energy X-ray absorptiometry, and blood and urinary bone metabolic parameters were analyzed. The decrease of lumbar bone mineral density, which took place during treatment, continued during the first 3 months after the cessation of treatment and did not return to the initial baseline level even at 6 months after the withdrawal of treatment. The biochemical parameters, which showed a state of enhanced bone turnover during nafarelin treatment, almost returned to the pretreatment level 6 months after the termination of treatment. CONCLUSION: These results indicate that relatively long period of bone metabolic change might be required to alter the actual bone mineral density after GnRH analog administration.

Administration, Intranasal↗
PubMed1995

Detection of messenger RNA for gonadotropin-releasing hormone (GnRH) but not for GnRH receptors in mouse mammary glands.

While gonadotropin-releasing hormone (GnRH), GnRH-like, or GnRH receptor (GnRH-R) have been reported to exist in several tissues other than brain or anterior pituitary, there is no report concerning GnRH or GnRH-R gene expression in the normal mammary gland. In order to define the production of GnRH as well as GnRH-R in the mammary gland at the molecular level we examined their gene expression in various functional stages of the mouse mammary gland using the reverse transcriptase-polymerase chain reaction (RT-PCR). GnRH mRNA transcripts were found in mouse mammary glands of mid-pregnant, lactating, and 3, 6, 9 days post-lactational mice, whereas GnRH-R mRNA transcripts were not detected in mammary glands of any functional stage. These results suggest a possible biological role of GnRH in mammary gland.

Animals↗
PubMed1995

Relation between gestational sac diameter, crown-rump length, and maternal serum estradiol, progesterone, and prolactin levels in early pregnancy.

In 152 patients with an early pregnancy which was subsequently normal, we measured the maternal serum levels of estradiol (E2), progesterone (P4) and prolactin (PRL) as well as the diameter of gestational sac (GS) and the crown-rump length (CRL) of the embryo by transvaginal ultrasonography. The maternal serum level of E2 had the closest statistically significant correlation with both the GS diameter (r = 0.769, P < 0.01) and the CRL (r = 0.736, P < 0.001). P4 and PRL concentrations showed less correlation with embryo development.

Crown-Rump Length↗
PubMed1995

Practical management of postmenopausal women with low bone mineral density.

For the management of postmenopausal women with low bone mineral density (BMD), the gynecologist, as a primary care physician, should play a central role in preventing osteoporotic fracture by educating them for elimination of risk factors and for healthy life-style and by providing an appropriate drug therapy. Because the risk of fracture usually increases after BMD decreases as much as 20-30% of peak bone mass, it is practically reasonable to set this level of BMD as a criteria for the initiation of management. As for a drug treatment, it is better to combine estrogen, the first choice drug, with progestogens to counteract any neoplastic effect of unopposed estrogen on the endometrium. Bisphosphonates and calcitonin, which are inhibitors of bone resorption, provide an alternative in prevention and treatment of postmenopausal bone loss in case of contraindication for estrogen or in those women who are unwilling to take estrogen.

Adult↗
PubMed1995

Posthemorrhagic hydrocephalus in a fetus with severe tachycardia.

Although posthemorrhagic hydrocephalus has been observed in premature infants, few cases of its intrauterine occurrence in fetuses have been reported. We report a case of posthemorrhagic hydrocephalus in a fetus with severe tachycardia. This case indicates that its possible occurrence should be considered in a case of a preterm fetus with distress.

Adult↗
PubMed1995

Regulation of human decidual function by epidermal growth factor.

In order to clarify a regulatory mechanism of epidermal growth factor (EGF) in the decidualization process, EGF gene expression, the change in EGF receptor, and the cell proliferative effect of EGF in the human endometrium/decidua were assessed in both in vivo and in vitro decidualization systems. Northern blot hybridization showed that, although no hybridized band was found in the proliferative and secretory phase endometria, a specific band of 5 kb was detected in decidua of early pregnancy as well as in in vitro medroxyprogesterone acetate-induced decidual cells. In situ hybridization revealed that prepro-EGF mRNA was observed in the stromal cells of decidua. Scatchard plot analysis of 125I-EGF-binding studies for the homogenates from these endometria/decidua revealed that its binding sites increased in accordance with the decidualization process, and its dissociation constant remained unchanged. EGF had a stimulatory action on cell proliferation in the early pregnant decidual cells. These results demonstrate that EGF production, EGF receptor, and decidual cell growth increase in accordance with the process of decidualization, suggesting that EGF may play an important role in the regulation of decidualization in human endometrium through an autocrine/paracrine system.

Blotting, Northern↗
PubMed1995

Epidermal growth factor stimulates the cell growth of the PA-1 teratocarcinoma cell line in an autocrine/paracrine fashion.

In order to investigate the biological significance of epidermal growth factor (EGF) in the cell function of teratocarcinoma cells, we examined the production, binding and cell proliferative effect of EGF in PA-1 human ovarian teratocarcinoma cell line. The immunoreactivity of EGF in PA-1 cell-conditioned medium was detected by human EGF radioimmunoassay, and prepro-EGF mRNA was demonstrated in PA-1 cells by Northern blot analysis. An [125I]EGF binding study showed the presence of EGF receptor with very high binding affinity and relatively low numbers of binding sites in PA-1 cells. Furthermore, the growth of PA-1 cells was stimulated by EGF and inhibited by anti-EGF monoclonal antibody. These results suggest strongly that EGF plays an important role in controlling the growth of teratocarcinoma cells as an autocrine/paracrine growth factor.

Blotting, Northern↗
PubMed1995

Effects of epidermal growth factor and transforming growth factor alpha on the mouse trophoblast outgrowth in vitro.

In order to analyze the involvement of growth factors in the implantation mechanism, we examined the direct effects of epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha) on trophoblast outgrowth of the mouse blastocyst in vitro. ICR mouse blastocysts were cultured for 4 days on a culture plate in medium containing EGF or TGF-alpha or conditioned medium obtained from cultured endometrial epithelial cells. Blastocysts were also co-cultured with endometrial epithelial cells. The trophoblast outgrowth of these cultured blastocysts was observed daily and the percentage of outgrowing embryos was calculated and analyzed statistically by the chi-squared test. Analysis for the specific binding of 125I-EGF in outgrown trophoblasts was carried out by autoradiography. The co-culture (days 3 and 4) and the presence of EGF (10 ng/ml, day 4), TGF-alpha (1 ng/ml, day 3; 10 ng/ml, days 2 and 3; 50 ng/ml, days 2-4) or conditioned medium (days 3 and 4) significantly stimulated the rate of trophoblast outgrowth. Preincubation of the conditioned medium with monoclonal anti-EGF or anti-TGF-alpha antibody suppressed the stimulatory effect of the conditioned medium on trophoblast outgrowth. The specific 125I-EGF binding in outgrown trophoblasts was demonstrated by autoradiography. These results suggest that EGF and TGF-alpha play an important role in the implantation process by directly stimulating trophoblast development.

Animals↗
PubMed1994

Visualization of mitotic chromosomes in filamentous fungi by fluorescence staining and fluorescence in situ hybridization.

Mitotic chromosomes of the plant pathogenic filamentous fungi Botrytis cinerea and Alternaria alternata were observed. Chromosomes prepared by the germ tube burst method were stained with the fluorescent dye 4',6-diamidino-2-phenylindole (DAPI) to yield figures with good resolution. Using this method, component chromosomes were clearly distinguished and the chromosome number could be determined. Fluorescence in situ hybridization (FISH) was also successfully applied to the specimens, revealing one ribosomal RNA gene cluster, or nucleolus organizer region (NOR) in the genome of each fungus. A long attenuated chromatid thread expanding from a condensed metaphase chromosome, which had been called a thread-like structure in B. cinerea, was proved to be an NOR. This is the first report of the successful application of FISH to the chromosomes of filamentous fungi.

Alternaria↗
PubMed1994

Gene expression of epidermal growth factor in human endometrium during decidualization.

Although there are some reports, including our previous study, indicating the existence and biological action of epidermal growth factor (EGF) in human decidua, the site of its synthesis remains unknown. To clarify the EGF production during decidualization at a molecular level, gene expression of EGF in human endometrium/decidua was examined by Northern blot analysis and in situ hybridization. Northern blot hybridization using 32P-labeled human prepro-EGF complementary DNA was carried out for nonpregnant human endometria from hysterectomized uteri of leiomyoma, decidua from early pregnancy, and in vitro decidualized endometrial cells by medroxyprogesterone acetate (MPA). Although no hybridized band was found in the proliferative and secretory phase endometria, a specific band of 5 kilobases, in agreement with the size of human prepro-EGF messenger ribonucleic acid, was detected in decidua of early pregnancy as well as in in vitro MPA-induced decidual cells. In situ hybridization revealed that prepro-EGF messenger ribonucleic acid was observed in the stromal cells of decidua. These results demonstrate that the EGF gene is expressed in the process of decidualization, suggesting that EGF may play an important role in the decidualization process of human endometrium.

Blotting, Northern↗
PubMed1993

Ontogenesis and distribution of epidermal growth factor immunoreactivity and binding activity in the mouse fetal and neonatal tissues.

Epidermal growth factor (EGF) immunoreactivity, EGF binding activity, and their ontogenic changes were investigated in placenta, amnion, and various organs of mouse fetus and neonate. EGF immunoreactivity was detected in all organs examined such as fetal and neonatal liver, brain, lung, intestine, placenta, and amnion. The fetal tissues having relatively higher EGF content were amnion, liver, and intestine. The tissue distribution of EGF immunoreactivity in the fetus did not differ from that in neonate. As for its ontogenesis, EGF immunoreactivity was almost constant during fetal development in liver, brain, and placenta, whereas it gradually increased in intestine. Scatchard plot analysis of EGF receptor, which was also demonstrated in all organs studied, revealed that EGF receptor in these tissues showed curvi-linear profile and its affinity was very high. Unlike EGF immunoreactivity, EGF binding activity showed tissue distributional difference between fetus and neonate except skin; EGF binding activity was relatively high in heart, kidney, lung, and intestine in the fetus, whereas it was high in liver, kidney, heart, and lung in the neonate. As for its ontogenesis, EGF receptor increased in liver as gestation proceeded, while it decreased in intestine. These results suggest that the biological importance of EGF in fetal development may be variable among fetal organs despite the ubiquitous existence of EGF and its receptor in many fetal tissues.

Animals↗
PubMed1992

[Role of growth factors in the regulation of embryo development and implantation].

Although it has been reported that growth factor and extracellular matrix (ECM) play an important role in the control of cell proliferation and differentiation in general, their involvement in the regulation of early embryogenesis and implantation is poorly understood. In order to clarify the mechanism underlying establishment and maintenance of pregnancy, the effect of EGF, TGF-alpha, TGF-beta, TN (tenascin) on the development of preimplantation embryo and endometrial function were investigated. 1. Growth factors in early embryogenesis. EGF did not exert any significant effect on the development of mouse 2-cell embryo in vitro. RT-PCR revealed the presence of EGFmRNA in blastocyst and 2-cell embryo, in which it may be derived from maternal genome. PA-1 cells, human teratocarcinoma-derived cell line, share biochemical characteristics with embryo developed at and beyond blastocyst stage. Anti-EGF antibody but not EGF exerted inhibitory effect on DNA synthesis in PA-1 cell, which produced and secreted immunoreactive and bioactive EGF and contained high-affinity EGF receptor. These results indicate that autocrine/paracrine mechanism of EGF action may be a key regulation of embryo development at and beyond blastocyst stage. 2. Growth factors and ECM in implantation. The luminal fluid in DES-stimulated mouse uterus contained high concentrations of EGF and TGF-alpha. In vivo administration of EGF, like estrogen, stimulated uterine epithelial proliferation as well as progesterone receptor levels. In vivo administration of anti-EGF antibody or anti-TGF-alpha antibody significantly reduced estrogen-induced labelling index in castrated mouse uterus. The concomitant administration of TGF-beta 1 and TGF-beta 2 with estrogen further stimulated DNA synthesis in the mouse uterus than estrogen alone. These results suggest that growth factors partly may be a mediator of estrogen actions on the uterine cell proliferation and the induction of progesterone receptor, which are important preparative steps for implantation. Northern blotting and in situ hybridization using cDNA probe for mouse prepro EGF revealed the presence of prepro EGFmRNA in the early pregnant mouse uterus, especially in stroma/decidua in Day 6 of pregnancy. EGF and TGF-alpha significantly stimulated trophoblast outgrowth of the mouse blastocyst in vitro in supplementation with 0.1% of fetal bovine serum. The specific binding of EGF was detected in the outgrown trophoblastic cells and inner cell mass of cultured blastocysts by autoradiography. From these findings, it may be possible that EGF produced in stromal/decidual cells exerts stimulatory effect on trophoblast outgrowth, playing an important role in the interaction between embryo and endometrium.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Effect of prolactin (PRL) on lipoprotein lipase (LPL) activity in the rat fetal liver.

In order to clarify the possible involvement of PRL in the regulation of lipid metabolism, the influence of PRL on the levels of LPL activity in rat fetal liver was investigated. Rat fetuses at 18th day of gestation in one uterine horn were injected with o-PRL while those in the opposite horn with saline. Forty-eight hr later, the livers were removed from the fetuses, homogenized, defatted, dried overnight, and further homogenized to the enzyme suspension. The measurement of LPL activity in these suspensions revealed that LPL activity in the fetal liver treated with o-PRL was significantly higher than that of control. LPL activities in the rat fetal liver gradually increased until the time of birth as the gestation proceeded. These results suggest that PRL may be one of the factors regulating fetal lipid metabolism.

Animals↗
PubMed1990

Epidermal growth factor stimulate cell proliferation and inhibits prolactin secretion of the human decidual cells in culture.

Epidermal growth factor (EGF) has been found to be mitogenic in a variety of tissues. We investigated the biological effect of EGF on early pregnant human decidua and the non-pregnant decidualized human endometrium in the primary cell culture. EGF had a stimulatory action on cell proliferation in the early pregnant decidual cells and an inhibitory effect on prolactin (PRL) secretion from the decidual cells. The addition of progesterone into culture medium suppressed cell proliferation of decidual cells, whereas it enhanced PRL secretion from decidua. The analysis of the specific receptor for EGF in the early pregnant decidua and non-pregnant decidualized endometrium revealed that both tissues had a single component EGF receptor with a dissociation constant of nM order. These results suggest that EGF may play a role in the growth and function of endometrial stromal cells.

Cell Division↗