Search PubMed⌕ Search

Biomedical subjects

Y Taketani

Publications and source records attributed to Y Taketani.

At least 73 records · Page 4Linked to original sources
PubMed2000

Constitutive tyrosine phosphorylation of ErbB-2 via Jak2 by autocrine secretion of prolactin in human breast cancer.

Overexpression of the oncogene for ErbB-2 is an unfavorable prognostic marker in human breast cancer. Its oncogenic potential appears to depend on the state of tyrosine phosphorylation. However, the mechanisms by which ErbB-2 is constitutively tyrosine-phosphorylated in human breast cancer are poorly understood. We now show that human breast carcinoma samples with ErbB-2 overexpression have higher proliferative and metastatic activity in the presence of autocrine secretion of prolactin (PRL). By using a neutralizing antibody or dominant negative (DN) strategies or specific inhibitors, we also show that activation of Janus kinase Jak2 by autocrine secretion of PRL is one of the significant components of constitutive tyrosine phosphorylation of ErbB-2, its association with Grb2 and activation of mitogen-activated protein (MAP) kinase in human breast cancer cell lines that overexpress ErbB-2. Furthermore, the neutralizing anti-PRL antibody or erbB-2 antisense oligonucleotide or DN Jak2 or Jak2 inhibitor or DNRas or MAP kinase kinase inhibitor inhibits the proliferation of both untreated and PRL-treated cells. Our results indicate that autocrine secretion of PRL stimulates tyrosine phosphorylation of ErbB-2 by Jak2, provides docking sites for Grb2 and stimulates Ras-MAP kinase cascade, thereby causing unrestricted cellular proliferation. The identification of this novel cross-talk between ErbB-2 and the autocrine growth stimulatory loop for PRL may provide new targets for therapeutic and preventive intervention of human breast cancer.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Human NB-2 of the contactin subgroup molecules: chromosomal localization of the gene (CNTN5) and distinct expression pattern from other subgroup members.

NB-2 is one of the neural recognition molecules in the contactin subgroup, which belongs to the immunoglobulin superfamily. In rat, the six molecules in this subgroup that have been reported to date are contactin, TAG-1, BIG-1, BIG-2, NB-2, and NB-3. We have isolated cDNAs encoding the two splicing isoforms of human NB-2. The long isoform of human NB-2 consists of 1100 amino acids residues that are 91% homologous to rat NB-2 at the amino acid sequence level. The short isoform lacks 74 amino acid residues between residues 19 and 93 of the long isoform. Among various regions of the adult human brain, high-level expression of NB-2 was detected in the amygdala and occipital lobe, whereas expression was low in the corpus callosum, caudate nucleus, and spinal cord. Although there were some differences, the expression pattern of NB-2 was the most similar to that of BIG-1 in the brain. Likewise, contactin and BIG-2 exhibited similar expression patterns. The expression of TAG-1 showed the least regional differences. The human NB-2 gene (CNTN5) was mapped to chromosome 11q21-q22.2 by fluorescence in situ hybridization. Our results suggest that the NB-2 gene may contribute to human neurological disorders.

Alternative Splicing↗
PubMed2000

Enhanced oncogenicity of human papillomavirus type 16 (HPV16) variants in Japanese population.

To investigate whether HPV16 E6 variants carry an elevated risk for cervical cancer in Japanese population, we investigated the E6 sequence variation in 40 cervical intraepithelial neoplasias (CINs) I-III and 43 invasive cervical cancers (ICCs), all positive for HPV16. HPV16 E6 variants were frequently found in ICCs than in CINs (88 vs. 65%, P=0.01). The E6 D25E, a rare variant in Western countries, was most frequently observed in ICC (44%). CIN I/II lesions with HPV16 variants were less likely to regress than those with HPV16 prototype (P=0.048). The finding that HPV16 E6 variants represent a significant risk factor is common between Western and Japanese women despite the different distribution of each variant.

Base Sequence↗
PubMed2000

Estrogen receptor-mediated effects of a xenoestrogen, bisphenol A, on preimplantation mouse embryos.

The effects of bisphenol A, a xenoestrogen widely used in industry and dentistry, were studied in early preimplantation mouse embryos. Two-cell mouse embryos were cultured with 100 pM to 100 microM bisphenol A with or without 100 nM tamoxifen and evaluated at 24-h intervals for their development to eight-cell and blastocyst stages. At 72 h, blastocysts were cultured for another 48 h without bisphenol A, and surface areas of trophoblast spread were measured. At 24 h, more embryos exposed to 3 nM bisphenol A than to controls had reached the eight-cell stage. At 48 h, more embryos exposed to 1 nM and 3 nM bisphenol A than to controls had become blastocysts. At 100 microM, bisphenol A decreased frequency of development to blastocysts. Tamoxifen counteracted both stimulatory and inhibitory effects of bisphenol A on blastocyst formation. Although bisphenol A did not alter blastocyst morphology or cell number, early exposure to 100 microM bisphenol A increased subsequent trophoblast areas. These findings suggest that bisphenol A may not only effect early embryonic development via estrogen receptors even at low, environmentally relevant doses, but also exert some late effects on subsequent development of these embryos.

Animals↗
PubMed2000

DNA vaccination of mice with plasmid expressing human papillomavirus 6 major capsid protein L1 elicits type-specific antibodies neutralizing pseudovirions constructed in vitro.

Human papillomavirus 6 (HPV 6) causes benign condylomata. As a model for HPV vaccine development, we tested a HPV 6 DNA vaccine candidate, constructed by subcloning the major capsid protein (L1) gene into an expression plasmid having the cytomegalovirus promoter, for its immunogenicity in BALB/c mice. Three intracutaneous inoculations of the plasmid with a gene gun at 2-week intervals elicited anti-L1 serum antibodies. The antibodies were found to recognize highly type-specific, conformation-dependent epitopes, including those to neutralize pseudovirions capable of inducing beta-galactosidase in infected monkey COS-1 cells. The data support the idea that immunization with DNA capable of expressing HPV L1 can be used as an HPV vaccine strategy for humans.

Animals↗
PubMed2000

Ubiquitous presence of E6 and E7 transcripts in human papillomavirus-positive cervical carcinomas regardless of its type.

The presence of human papillomavirus (HPV) DNA in almost all of the cervical carcinomas is one of the most compelling evidence for the viral carcinogenesis. HPVs are thought to induce cervical carcinoma most likely through the expression of E6 and E7 genes presumably by inactivating the tumor suppressor proteins, p53 and pRb, respectively. Thus far, the presence of HPV E6 and E7 transcripts have been identified only in cervical carcinoma-derived cell lines harboring type 16 or 18, and in a limited number of cervical neoplasia specimens positive for type 16, 18, 33 or 51. To see whether the expression of E6 and E7 genes is an essential finding in HPV-positive cervical carcinoma and cervical intraepithelial neoplasia (CIN), we constructed a reverse transcription-polymerase chain reaction (RT-PCR) assay using a pair of consensus primers in the E6 and E7 regions. Using the assay, E6 transcripts (full-length E6/E7 transcripts) and E7 transcripts (spliced E6/E7 transcripts, E6* mRNA) were identified in 97% (30/31) and 100% (all 31) of cervical carcinomas and in 100% (all 23) and 74% (17/23) of CINs, respectively. This assay also revealed unknown splice donor and acceptor sites of E6* mRNA of less frequent HPV types 31, 35, 52, 56, 58 and 59 based on sequence analyses of the PCR products. Thus, the present study demonstrates that E6 and E7 transcripts of HPV exist in virtually all HPV-positive cervical neoplasia specimens except for the absence of E7 transcripts in some of CINs.

Base Sequence↗
PubMed2000

Prenatal detection of a high-risk group for intrauterine growth restriction based on sonographic fetal biometry.

OBJECTIVE: This study was performed to evaluate the significance of sonographic fetal biometry in predicting low birth weight. METHOD: Five hundred and sixty-eight single-term pregnancies were analyzed. They were stratified into seven subgroups by birth weight deviation (BWD). Among the 568 pregnancies, 115 were revealed to be small-for-gestational-age (SGA) (birth weight less than mean -1.5 S. D.). When IUGR was suspected by routine sonographic fetal biometry, 'IUGR work-up' was carried out. The diagnostic performance of our screening method for the detection of SGA pregnancies in the general population was calculated. RESULT: The sensitivity, specificity, positive predictive value, negative predictive value and odds ratio of our screening method for the detection of SGA pregnancies in the general population were 73.0, 96.6, 83.2, 98.0% and 131.0, respectively. CONCLUSION: These data suggest that sonographic biometry is useful for the prenatal detection of high-risk cases of fetal growth restriction.

Biometry↗
PubMed2000

Schnurri interacts with Mad in a Dpp-dependent manner.

BACKGROUND: Decapentaplegic (Dpp) is a member of the transforming growth factor-beta superfamily. Dpp governs various developmental processes in Drosophila through the transcriptional regulation of a variety of genes. Signals of Dpp are transmitted from the cell membrane to the nucleus by Medea and Mad, both belonging to the Smad protein family. Mad was shown to bind to the Dpp-responsive element in genes such as vestigial, labial, and Ultrabithorax. The DNA binding affinity of Smad proteins is relatively low, and requires other nuclear factor(s) to form stable DNA binding complexes. schnurri (shn) was identified as a candidate gene acting downstream of Dpp receptors, but its relevance to Mad has remained unknown. RESULTS: We characterized the biochemical functions of Shn. Shn forms homo-oligomers. Shn is localized in the nucleus, and is likely to have multiple nuclear localizing signals. Finally, we found that Shn interacts with Mad in a Dpp-dependent manner. CONCLUSIONS: The present results argue that Shn may act as a nuclear component of the Dpp signalling pathway through direct interaction with Mad.

Animals↗
PubMed2000

Prenatal evaluation of cephalopagus conjoined twins by means of three-dimensional ultrasound at 13 weeks of pregnancy.

Cephalopagus twinning, an extremely rare type of conjoined twins, is characterized by the anterior union of the upper half of the body, with two faces each situated on the opposite side of a conjoined head. The prognosis for cephalopagus twins is extremely poor because surgical separation is not an option. Thus early prenatal diagnosis of cephalopagus twins is important to provide an opportunity for pregnancy termination if desired. However, in many instances, cephalopagus twins are misdiagnosed as a singleton pregnancy because of the extreme degree of fusion which makes accurate demonstration of the abnormalities very difficult. This report presents a case of cephalopagus twins which was confirmed at 13 weeks of gestation using three-dimensional ultrasound.

Adult↗
PubMed2000

Increased concentrations of soluble tumour necrosis factor receptor (sTNFR) I and II in peritoneal fluid from women with endometriosis.

Tumour necrosis factor alpha (TNFalpha), a proapoptotic cytokine, is known to be present in peritoneal fluid from women with endometriosis. An emerging view is that soluble TNF receptors (sTNFR) can modulate the effects of TNFalpha by acting as TNFalpha antagonists. To assess the relevance of sTNFRs in the pathophysiology of endometriosis, concentrations of sTNFR I, sTNFR II and TNFalpha in peritoneal fluid from women with endometriosis (n = 53) and without endometriosis (n = 40) were measured. Concentrations of both sTNFR I and sTNFR II in peritoneal fluid from women with endometriosis were significantly higher than in peritoneal fluid from women without endometriosis, both in the follicular and the luteal phases. TNFalpha concentrations did not differ in patients with and without endometriosis in both phases. When stratified by the stage of the disease, women with both stages I/II and stages III/IV exhibited significantly higher concentrations of sTNFR I and sTNFR II in peritoneal fluid, compared with women without endometriosis, whereas no appreciable difference in the concentrations was detected between stages I/II and stages III/IV. A significant correlation was found between the concentrations of sTNFR I and sTNFR II; while the correlations between TNFalpha and sTNFR I or sTNFR II, were either not significant or were very weak. Furthermore, mRNA for the membrane-associated TNF receptor type 1 and TNF receptor type 2, both of which convey the effects of TNFalpha, were shown to be expressed in endometriotic tissues as well as eutopic endometrium. Together, these findings suggest a possible involvement of sTNFRs in the pathophysiology of endometriosis.

Adult↗
PubMed2000

Regulation of nitric oxide synthase to promote cytostasis in ovarian follicular development.

Our own recent studies have demonstrated that inducible nitric oxide synthase (iNOS) is predominantly localized in granulosa cells of healthy immature follicles in the rat ovary, whereas granulosa cells of either healthy mature follicles or follicles destined to be atretic are devoid of iNOS. These findings suggest that iNOS is pivotal for immature follicles to remain dormant. To test this hypothesis, we examined the effects of a GnRH agonist (buserelin), a proapoptotic substance, and epidermal growth factor (EGF), a mitogenic and, consequently, antiapoptotic factor, on the amount of iNOS mRNA in rat granulosa cells. Administration of buserelin in immature female rats transiently diminished iNOS mRNA levels in the ovaries as determined by Northern blot analysis. In cultured rat granulosa cells, buserelin and EGF increased the incidence of apoptosis and DNA synthesis, respectively, whereas both reduced iNOS mRNA levels as determined by reverse transcription-coupled polymerase chain reaction. The concomitant addition of S-nitroso-N-acetyl-DL-penicillamine, an NO donor, together with buserelin or EGF eliminated the observed effects of these substances (i.e., induction of apoptosis and stimulation of DNA synthesis, respectively). These results suggest that the changes in developmental status of immature follicles either into development or atresia are associated with reduced iNOS levels in granulosa cells, thus reinforcing the notion of NO as a cytostatic factor in ovarian follicles.

Animals↗
PubMed2000

Immunotherapy prevents recurrent abortion without influencing natural killer receptor status.

PROBLEM: We assessed the expression of natural killer (NK) receptors in recurrent aborters before and after immunotherapy using their husbands' peripheral blood mononuclear cells (PBMCs). METHOD OF STUDY: Using stored PBMCs from recurrent aborters before and after the immunotherapy, the expression of NK receptors, CD158a, CD158b, CD159 and CD94, were analyzed using monoclonal antibodies for respective receptors. The diversity of killer activatory receptors (KARs) and killer inhibitory receptors (KIRs) was also examined using reverse transcriptase-polymerase chain reaction (RT-PCR)-single strand conformation polymorphism (SSCP) method. RESULTS: In recurrent aborters, no apparent changes in NK receptor expression and the balance between KARs and KIRs were found before and after the immunotherapy. CONCLUSION: The allo-human leukocyte antigen (HLA)-stimulation caused by the immunotherapy for recurrent aborters did not affect the expression of NK receptors and the ratio of KARs to KIRs regardless of the outcome of subsequent pregnancies, suggesting that recurrent aborters may benefit from the immunotherapy through mechanisms unrelated to alteration in NK receptor status.

Abortion, Habitual↗
PubMed2000

Stem cell factor (SCF) concentrations in peritoneal fluid of women with or without endometriosis.

PROBLEM: In the quest for possible involvement of stem cell factor (SCF), a cytokine known to have multiple effects, in the pathogenesis of endometriosis, we evaluated concentrations of SCF in peritoneal fluid (PF) of women with or without endometriosis. METHOD OF STUDY: SCF concentrations in PF collected from women undergoing laparoscopy were measured, using a specific enzyme-linked immunosorbent assay (ELISA). Reverse transcription-polymerase chain reaction (RT-PCR) analysis to detect gene expression of c-kit, the receptor for SCF, was performed using the endometriotic tissue and the eutopic endometrium collected during the operation. RESULTS: SCF concentrations in PF of women with endometriosis were significantly higher compared to women without endometriosis. Looking at SCF concentrations in PF of women with endometriosis stratified by disease stage, women with stage I and II exhibited relatively higher SCF levels in PF, whereas SCF levels in PF with stage III and IV were comparable with those without endometriosis. The expression of mRNA for c-kit was detected in both the endometriotic tissue and the eutopic endometrium. CONCLUSION: We demonstrated an elevation in SCF levels in PF associated with endometriosis and the presence of its receptor in endometriotic tissues. Given the known pleiotropic properties of SCF, the present results suggest that SCF might play a role in the pathogenesis of endometriosis.

Adult↗