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Biomedical subjects

M Taga

Publications and source records attributed to M Taga.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cell adhesion and reproduction. An overview.

Cell adhesion is essential for the regulation of many cellular functions. The adhesion molecule plays a critical role as a fundamental substance in various processes of reproduction such as trophoblast-endometrial interaction. Our understanding of the physiology of adhesion molecules will be helpful for clinical application of these molecules in the treatment and assessment of disorders of many processes of reproduction. We will briefly review integrins, cadherins, and laminin, which were the principal subjects of discussion in this conference.

Cadherins↗
PubMed1998

The effect of gonadotropin-releasing hormone agonist on type I collagen C-telopeptide and N-telopeptide: the predictive value of biochemical markers of bone turnover.

To evaluate the clinical utility of recently developed biochemical markers in the assessment of bone metabolism during GnRH agonist (GnRHa) treatment, we compared five bone resorption markers [C-telopeptide (CTX) and N-telopeptide (NTX) of type I collagen, hydroxyproline (Hpr), pyridinoline (Pyr), and deoxypyridinoline (Dpyr)] and two bone formation markers [total alkaline phosphatase (Alp) and osteocalcin (OC)]. Sixty-eight normally menstruating women were injected with a long-acting GnRHa once a month for 24 weeks for the treatment of endometriosis or leiomyoma. The mean percentage bone loss at the lumbar spine was 3.79% at the end of treatment. Although levels of all markers increased significantly as the treatment progressed, CTX and NTX exhibited the highest correlation coefficients between bone loss at 24 weeks and the seven markers measured at 0, 4, 12, 16, and 24 weeks of treatment. Serum estradiol levels were similarly suppressed during the treatment in both fast losers (whose bone loss was more than the mean) and slow losers (whose bone loss was less than the mean). However, significantly higher z-scores of bone resorption markers, but not of bone formation markers, were observed in the fast losers at 24 weeks of treatment, suggesting a more accelerated bone resorption in this group. Whereas the three highest z-scores at 24 weeks of treatment were CTX, NTX, and Dpyr (in that order), the highest z-score (P < 0.05) was observed for CTX in the fast losers. The subjects in the highest quartile of CTX, the highest, and second highest quartiles of NTX at 24 weeks of treatment experienced 2.1, 2.2, and 1.7 times more bone loss (P < 0.001), respectively, than those in the lowest quartiles. Furthermore, the subjects in the highest quartile of both CTX and NTX experienced 3.6 times more bone loss (P < 0.001) than those in the lowest quartile of both markers. These results indicate that both CTX and NTX are useful and sensitive markers for bone resorption in a hypoestrogenic state induced by GnRHa.

Adult↗
PubMed1997

Gene expression of gonadotropin-releasing hormone, but not its receptor, in human endometrium and decidua.

Gonadotropin-releasing hormone (GnRH) has been reported to exist in extrahypothalamic tissues such as the placenta, gonads and mammary glands. While we have reported the presence of GnRH-mRNA in the rodent uterus, there have been no reports concerning gene expression of GnRH and its receptor (GnRH-R) in human endometrial tissue. In order to investigate the role of GnRH as a local regulator in the human endometrium, we examined the gene for GnRH and GnRH-R in non-pregnant endometrium and decidua of early pregnancy. Using reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blot analysis we found GnRH-mRNA but not GnRH-R-mRNA transcripts in the human endometrium and decidua at 7-9 weeks gestation. This is the first report that suggests GnRH gene expression in the human endometrium/decidua.

Blotting, Southern↗
PubMed1997

Gene expression and specific binding of platelet-derived growth factor and its effect on DNA synthesis in human decidual cells.

To clarify the biological significance of platelet-derived growth factor (PDGF) in human decidual cell function, which is important for the maintenance of pregnancy, we investigated gene expression of the PDGF subunits, PDGF-A and PDGF-B, specific binding of the PDGF isoform, and the effect of PDGF dimers on DNA synthesis in human decidual cells. We detected in decidua from early pregnancy the expected DNA bands of PDGF-A and PDGF-B by reverse transcriptase-polymerase chain reaction (RT-PCR) as well as mRNAs of each PDGF subunit by Northern blot hybridization, demonstrating that both PDGF subunits exist in this tissue. Scatchard plot analysis showed that decidual cells had both PDGF-alpha and PDGF-beta receptors. PDGF-AA, -AB and -BB stimulated [3H]-thymidine incorporation in cultured decidual cells in a dose-dependent manner. These results indicate the importance of PDGF in human decidua.

Binding Sites↗
PubMed1997

The change in tenascin expression in mouse uterus during early pregnancy.

PURPOSE: Our aim was to examine the changes in spatiotemporal tenascin (TN) expression in mouse uterus during early pregnancy, when the uterine tissue undergoes a tremendous restructuring. METHODS: Using immunohistochemistry and in situ hybridization, the changes in distribution of TN protein in mouse uterine tissues in pregnancy Day 0 through Day 5 were analyzed. RESULTS: Immunoreactive TN and TN mRNA were expressed in the basement membrane of the epithelium as well as in the smooth muscle layer, and their distribution shifted from the subbasement region on Day 0-3 to the smooth muscle layer on Days 4 and 5. CONCLUSIONS: These results indicate that TN expression in the uterus during early pregnancy is spatiotemporally different and may be regulated by a different mechanism.

Animals↗
PubMed1997

Gene expression of transforming growth factor-alpha in human endometrium during decidualization.

PURPOSE: We previously reported the gene expression of epidermal growth factor (EGF) in the process of decidualization in the human endometrium. This study was undertaken to investigate the biological significance of transforming growth factor-alpha (TGF-alpha), which shares a significant sequence homology with EGF, in the regulation of decidualization. METHODS: The gene encoding TGF-alpha was analyzed by Northern blot hybridization in nonpregnant human endometria and decidua from 6 to 8 weeks of gestation as well as in cultured stromal cells with or without medroxyprogesterone acetate. RESULTS: No transcript was detected in proliferative and secretory endometrium, whereas a transcript of 4.8 kb, which was in agreement with the size of human prepro-TGF-alpha mRNA previously reported, was clearly detected in decidua. Transcript of 4.8 kb was also detected in vitro in medroxyprogesterone acetate (MPA)-induced decidual cells, while no TGF-alpha transcript was found in endometrial stromal cells cultured without MPA. CONCLUSIONS: These results suggest that the gene expression of TGF-alpha in uterine stromal cells is enhanced by stimulation from sex steroids and that TGF-alpha, like EGF, functions as one of the regulatory factors for decidualization in the human uterus.

Blotting, Northern↗
PubMed1997

Prolactin secretion in endometriotic patients.

OBJECTIVE: To clarify a significance of prolactin (PRL) for infertility in endometriosis. STUDY DESIGNS: For seventy endometriotic patients with or without infertility, serum PRL concentrations measured by radioimmunoassay before and 30 min after 500 micrograms of thyrotropin-releasing hormone (TRH) injection were analyzed in relation to the Revised American Fertility Society score in endometriosis as well as to the outcome of the treatment for endometriotic infertility. RESULTS: While no significant relationship was found between the basal PRL levels and the stage of endometriosis or the outcome of the treatment for infertility, the PRL value after TRH injection was significantly greater in the patients who did not become pregnant than those who did (P < 0.05). CONCLUSIONS: Occult hyperprolactinemia may be involved in infertility in endometriotic patients.

Adolescent↗
PubMed1997

Changes in urinary excretions of C-telopeptide and cross-linked N-telopeptide of type I collagen during pregnancy and puerperium.

Previously we reported an increase in bone resorption during pregnancy and lactation by measuring pyridinoline (Pyr) and deoxypyridinoline (D-Pyr). To further assess bone metabolism during peripuerperal periods, we measured the urinary excretions of C-telopeptide (CTX) and cross-linked N-telopeptide (NTX) of type I collagen, new markers of bone resorption. In addition to Pyr and D-Pyr, urinary CTX and NTX were measured by two ELISAs which recognize the corresponding peptide of type I collagen after urine samples were collected cross-sectionally from 230 women who consisted of 187 pregnants, 25 puerperants, and 18 age-matched nonpregnant women. Urinary CTX was also measured longitudinally from 10 pregnants at 5-9, 28-31 and 36-39 weeks of gestation and 1, 3, 6 months after parturition. Similar to the changes in Pyr and D-Pyr, the mean CTX and NTX values significantly increased in the 3rd trimester of pregnancy and remained high during puerperium compared with nonpregnant or early pregnant women (P<0.05). In a longitudinal study, the mean CTX value significantly increased in the 3rd trimester of pregnancy and at 1 month of puerperium compared with that in the early stage of pregnancy (P<0.05). These results further confirm our previous evidence that bone resorption is enhanced during the 3rd trimester of gestation and puerperium and suggest that urinary CTX and NTX measured by ELISA, which is more convenient than HPLC, are useful markers to assess bone resorption during peripuerperal periods.

Adult↗
PubMed1997

Gene expressions of keratinocyte growth factor and its receptor in the human endometrium/decidua and chorionic villi.

Keratinocyte growth factor (KGF) is secreted from mesenchymal fibroblasts and has a mitogenic specificity for epithelial cells in a paracrine fashion. In order to clarify the biological significance of KGF in the human endometrium which undergoes dynamic changes under the influence of sex steroid hormone, we investigated the gene expressions of KGF and its receptor (KGF-R) in the human endometrium in various sex steroid hormone milieus and chorionic villi, by RT-PCR and Northern blot hybridization. The secretory phase endometrium had a KGF mRNA level 10-fold greater than that of the proliferative phase endometrium. Similarly abundant KGF mRNA was found in decidua and pseudopregnant endometrium compared with proliferative phase endometrium. The KGF-R mRNA was detected by RT-PCR in chorionic villi from early pregnancy. These results indicate that the gene for KGF expressed in the human endometrium is mainly regulated by progesterone and that KGF might have a role in the interaction between decidua and chorion in early pregnancy in man.

Blotting, Northern↗
PubMed1997

Change in C-terminal cross-linking domain of type I collagen in urine, a new marker of bone resorption, during and after gonadotropin-releasing hormone agonist administration.

OBJECTIVE: The major side effect of GnRH agonist (GnRHa) therapy is the reduction of bone mass. To analyze bone resorption by GnRHa, we measured the urinary excretion of C-terminal telopeptides of type I collagen (CTX), a new marker of bone resorption. METHODS: We used a new ELISA for CTX (CrossLaps) in a sample of 18 premenopausal women with leiomyoma who were treated with daily administration of 400 micrograms nafarelin or 900 micrograms buserelin for 16 weeks. RESULTS: Urinary CTX excretion increased significantly during GnRHa treatment and then decreased at 12 and 24 weeks after the cessation of GnRHa therapy. Whereas the excretory profile of CTX during GnRHa therapy was almost similar to that of pyridinoline (Pyr) or deoxypyridinoline (D-Pyr), both biochemical markers of bone resorption, the magnitude of the change in CTX was significantly greater than that in Pyr or D-Pyr. CONCLUSIONS: These results indicate that CTX could be a more sensitive marker for bone resorption than the currently used biochemical markers, and that CrossLaps ELISA is useful for therapeutic monitoring during and after GnRHa treatment.

Adult↗
PubMed1997

Endocytosis of serum albumin in regenerating rat liver.

Lysosomes, isolated from rat liver after 70% partial hepatectomy (PHX), were found, by Western blotting, to contain a considerable amount of serum albumin. The level of intralysosomal serum albumin after PHX showed biphasic patterns: it increased immediately after PHX, peaked at 30 min, rapidly declined within a few hours, rose again with a peak at 15 hr, and gradually declined thereafter. At 15 hr after PHX, the content of lysosomal proteins in the liver increased to twice the level of unoperated control, and the electron-microscopic observation of the isolated lysosomes revealed numerous large membrane-delimited structures with ground substances of variable electron opacities. The increase in the intralysosomal serum albumin at 30 min and 15 hr was accompanied by changes in the buoyant densities of endosomes in Percoll density gradients. At both time points, the density profiles of endosomes isolated from hepatectomized rats shifted to the denser direction, suggesting that PHX activates fusion and/or maturation of endosomes. Formaldehyde-treated bovine serum albumin is known to be taken up by the liver by receptor-mediated endocytosis. The uptake of the modified heterologous albumin was shown to be activated as early as 30 min after PHX. Both the uptake of serum albumin into lysosomes and the shift of buoyant density profile of endosomes after PHX were inhibited by the administration of adrenergic receptor antagonists, particularly by the alpha r-antagonist prazosin. Further, the concentration of catecholamines in rat serum, particularly that of norepinephrine, was found to increase immediately after PHX, relative to that in serum from sham-operated rats. These results suggest that the elevation of serum norepinephrine levels after PHX activates endocytosis and facilitates delivery of endocytosed serum albumin to lysosomes, where albumin is digested to yield amino acids for possible use in protein synthesis during liver regeneration.

Adrenergic alpha-Antagonists↗
PubMed1996

The effect of activin-A on the development of mouse preimplantation embryos in vitro.

PURPOSE: Our purpose was to clarify the involvement of transforming growth factor-beta (TGF-beta) family in the regulation of preimplantation embryo development. METHODS: The effects of activin-A and TGF-beta on the rates of morula and blastocyst formations as well as on the cleavage velocity of a mouse two-cell embryo in vitro were analyzed. The gene expressions of these two growth factors in various developmental stages were also studied using RT-PCR. RESULTS: Activin-A at a concentration of 0.2 ng/ml significantly stimulated not only the rate of morula formation but also the velocity of embryo cleavage, whereas no significant effect was found with TGF-beta. RT-PCR revealed that activin-A subunit mRNA, but not TGF-beta mRNA, was detected in preimplantation mouse embryo at any developmental stage. CONCLUSIONS: Activin-A plays an important role in the regulation of preimplantation mouse embryo development in an autocrine fashion.

Activins↗
PubMed1996

Gene expression of gonadotropin-releasing hormone in early pregnant rat and steroid hormone exposed mouse uteri.

While gonadotropin-releasing hormone (GnRH) or GnRH-like substance have been reported to exist in nonhypothalamic tissues such as placenta, gonads, and mammary gland, there have been no reports concerning the detection of GnRH mRNA in uterine tissue. In order to investigate the presence of GnRH in decidual tissues and its possible involvement in the regulation of placental function, we examined the gene for GnRH in the rodent uterus in early pregnancy and in nonpregnant animals treated with female sex steroids. Using RT-PCR and in situ hybridization we found GnRH mRNA transcripts in the rat uterus of 3rd and 6th day gestation and in the mouse uterus treated with estrogen and progesterone. In situ hybridization revealed that GnRH mRNA was localized in the endometrial stromal cells of the 3rd and 6th day of gestation. These results suggest the existence of GnRH gene expression in uterine stromal cells and its possible paracrine effect derived from the decidual cells.

Animals↗
PubMed1996

Transforming growth factor-alpha, like epidermal growth factor, stimulates cell proliferation and inhibits prolactin secretion in the human decidual cells in vitro.

In order to clarify the biological action of transforming growth factor alpha (TGF-alpha) in the human decidua, we investigated the effects of TGF-alpha on cell proliferation and prolactin (PRL) secretion in cultured decidual cells in vitro. TGF-alpha had a stimulatory effect on DNA synthesis in decidual cells and an inhibitory effect on PRL secretion from these cells. These results suggest that TGF-alpha, like epidermal growth factor (EGF), may be one of the substances which regulate decidual function.

Cell Division↗
PubMed1996

Two pregnancies in a 45,X/46,Xr(X)/46,XX Turner mosaic patient. A case report.

Turner's syndrome associated with an X ring chromosome, r (X), is rare and there has been no report on pregnancy in Turner's syndrome with 45,X/46,Xr (X)/46,XX mosaicism. A patient with this karyotype who lacked the clinical manifestation of characteristic phenotype of Turner's syndrome except for short stature had two pregnancies. This is the first case of successful pregnancy in patient with X,Xr(X),XX mosaic Turner's syndrome.

Adult↗