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T Ichimura

Publications and source records attributed to T Ichimura.

At least 19 recordsLinked to original sources
PubMed2006

The hepatitis B virus X protein enhances AP-1 activation through interaction with Jab1.

Hepatitis B virus X protein (HBx) has many cellular functions and is a major factor in hepatitis and hepatocellular carcinoma caused by HBV infection. A proteomic approach was used to search for HBx-interacting proteins in order to elucidate the molecular mechanism of hepatocarcinogenesis. HBx was attached to myc and flag tags (MEF tags) and expressed in 293T cells; the protein complex formed within the cells was purified and characterized by mass spectrometry. COP9 signalosome (CSN) subunits 3 and 4 were subsequently identified as HBx-interacting proteins. In addition, CSN subunit 5, Jun activation domain-binding protein 1 (Jab1), was shown to be a novel cellular target of HBx. In vivo and in vitro interactions between HBx and Jab1 were confirmed by standard immunoprecipitation and GST pull-down assays. An analysis of HBx deletion constructs showed that amino acids 30-125 of HBx were responsible for binding to Jab1. Confocal laser microscopy demonstrated that HBx was mainly localized in the cytoplasm, while Jab1 was found mainly in the nucleus and partially in the cytoplasm, and that the two proteins colocalized in the cytoplasm. The cotransfection of HBx and Jab1 resulted in substantial activator protein 1 (AP-1) activation and knockdown of endogenous Jab1 attenuated AP-1 activation caused by HBx. In addition, the coexpression of HBx and Jab1 potentiated phosphorylation of JNK, leading to the subsequent phosphorylation of c-Jun, whereas the level of c-Jun and JNK phosphorylation induced by HBx was decreased in Jab1 knockdown cells. These results suggest that the interaction between HBx and Jab1 enhances HBx-mediated AP-1 activation.

COP9 Signalosome Complex↗
PubMed2004

Quantitative evaluation of spatial coherence of the electron beam from low temperature field emitters.

By using multiwalled carbon nanotubes as an element of a nanobiprism, we evaluated quantitatively the coherence of electrons emitted from tungsten tips at room temperature and 78 K, and found an enhancement of coherence at 78 K. The increase of the transverse coherence length of the electron beam agreed well with that of the inelastic mean free path of electrons in solids, demonstrating the direct relationship between the coherences of the electron beam and the original electronic states. On the basis of this experimental fact, we comment on the interpretation of recent Hanbury Brown-Twiss type experiments for electrons reported by Kiesel et al. [Nature (London) 418, 392 (2002)]].

Journal Article↗
PubMed2001

Ovarian malignant mixed mesodermal tumor producing the free form of the beta-subunit of human chorionic gonadotropin.

We report a patient with ovarian malignant mixed mesodermal tumor (MMMT) that produced immunoreactive human chorionic gonadotropin beta-subunit (IR-hCG beta). Qualitative analysis indicated that IR-hCG beta in the patient's serum represented the free form of the beta-subunit of hCG. Immunohistochemical localization of hCG beta in MMMT was observed in the sarcomatous stroma, but not in the adenocarcinoma component. Reverse transcription-polymerase chain reaction (RT-PCR) for hCG subunits revealed that the mRNA transcripts of two of six hCG beta genes (beta-1 and -2) were predominantly expressed in the tumor tissue. The serum level of free hCG beta correlated with disease status and was helpful for monitoring the response to therapy for MMMT in this patient.

Adenocarcinoma↗
PubMed2001

Ultrastructural comparison of uterine leiomyoma cells from the same myoma nodule before and after gonadotropin-releasing hormone agonist treatment.

OBJECTIVE: To compare ultrastructural features of leiomyoma cells from the same uterine myoma nodule before and after GnRH agonist (GnRH-a) treatment and to examine the relation between these ultrastructural changes and the extent of myoma volume reduction with GnRH-a treatment. DESIGN: Prospective clinical study. SETTING: University teaching hospital. PATIENT(S): Twenty women with uterine leiomyomas who were scheduled for surgery. INTERVENTION(S): Transcervical needle biopsy of uterine myoma, s.c. leuprolide acetate injection (3.75 mg) at least three times every 4 weeks before surgery, and hysterectomy or myomectomy. MAIN OUTCOME MEASURE(S): The changes in ultrastructural features of uterine leiomyoma cells and the percentage decrease in the volume of the largest myoma at 12 weeks of GnRH-a treatment measured by magnetic resonance imaging. RESULT(S): A decrease in myofilaments, mitochondrial swelling, and emergence of the lysosomal body were observed in relation to GnRH-a treatment. Furthermore, a positive correlation was observed between the decrease in myofilaments and myoma shrinkage. CONCLUSION(S): Cellular atrophy due to a decrease in myofilaments plays a major role in the reversible myoma shrinkage resulting from GnRH-a treatment.

Adult↗
PubMed2001

Pancreas: imaging diagnosis with color/power Doppler ultrasonography, endoscopic ultrasonography, and intraductal ultrasonography.

Recent advances of ultrasound imaging have made possible to depict various diseases and conditions of the pancreas. Color/power Doppler ultrasonography, endoscopic ultrasonography, and intraductal ultrasonography are feasible to show vascular abnormalities, differentiate the solid and cystic tumors, decide tumor extent, and help to perform interventional treatments of the pancreatic diseases. Those techniques will contribute to the more precise and easier diagnosis and to prompt decision of the treatments of the pancreatic disorders. Radiologists should recognize the diagnostic feasibility and limitations of those techniques in order to avoid unnecessary examinations on the patients, and obtain precise diagnostic images.

Endoscopy, Gastrointestinal↗
PubMed2001

Virtual CT cholangioscopy: comparison with fiberoptic cholangioscopy.

BACKGROUND AND STUDY AIMS: No studies comparing virtual computed tomography (CT) cholangioscopy of the common bile duct compared with fiberoptic cholangioscopy are available. The aim of our study was to evaluate the feasibility of virtual CT cholangioscopy of the common bile duct. PATIENTS AND METHODS: The study population comprised 52 patients (25 women, 27 men; mean age 56.5, range 32 - 81) with biliopancreatic disorders. Endoscopic images were produced by a volume-rendering method and a perspective projection. The ability to detect the endoluminal view and abnormalities of the common bile duct by virtual CT cholangioscopy and fiberoptic cholangioscopy was evaluated. RESULTS: Except for two cases (4 %), virtual CT cholangioscopy revealed excellent and moderate endoluminal visualization. There was no significant difference between the techniques (virtual CT cholangioscopy vs. fiberoptic cholangioscopy: excellent, 73 % vs. 85 %, P = 0.149; moderate 23 % vs. 15 % (P = 0.319); poor, 4 % vs. 0 %, P = 0.153). Virtual CT cholangioscopy revealed no significantly different ability to detect stenosis and obstruction of the common bile duct, compared with fiberoptic cholangioscopy. However, the ability of virtual CT cholangioscopy to detect minute papillary tumors (virtual CT cholangioscopy 30 % vs. fiberoptic cholangioscopy 100 %, P = 0.001) and stones smaller than 5 mm (virtual CT cholangioscopy 25 % vs. fiberoptic cholangioscopy 100 %; P = 0.002 was significantly less than that of fiberoptic cholangioscopy. CONCLUSIONS: Virtual CT cholangioscopy cannot replace fiberoptic cholangioscopy completely. However, the use of this technique, instead of fiberoptic cholangioscopy, may be feasible for following up patients after biliary intervention.

Adult↗
PubMed2001

Immunohistochemical expression of gastric mucin and p53 in minimal deviation adenocarcinoma of the uterine cervix.

Comparative immunostaining with antibodies against gastric mucin and p53 was performed on 6 cases of minimal deviation adenocarcinoma (MDA) of the uterine cervix. The MDAs consisted of predominant areas of glands lined by extremely well-differentiated tall columnar epithelial cells with little cytological atypia and minor foci of less well-differentiated glandular epithelium with a minor degree of nuclear atypia. Immunostaining for gastric mucin with a monoclonal antibody HIK1083 revealed that all the tumors areas of typical MDA were partly immunoreactive for HIK1083, but the coexisting less well-differentiated glands were essentially negative. Four MDAs focally contained cells with p53 positive nuclei that were located exclusively in the less well-differentiated cells that lacked gastric mucin. In the pelvic lymph nodes in 2 cases, most of the metastatic tumor was less differentiated and a positive reaction for HIK1083 was observed only in small foci of typical MDA. No significant overexpression of p53 was observed in the metastases. Immunohistochemical expression of gastric mucin and p53 may be related to the histological differentiation of MDA, and detection of p53 overexpression may help to identify critical steps in the local progression of MDA.

Adenocarcinoma↗
PubMed2001

Congenital arteriovenous malformation of the pancreas: its diagnostic features on images.

To analyze diagnostic features on images of congenital arteriovenous malformation (AVM) of the pancreas, we analyzed the diagnostic findings in six patients with the disease, using gray-scale ultrasonography (US), color Doppler US, computed tomography, and angiography and analyzed previously reported cases. AVM characteristic findings on images were multiple, small hypoechoic nodules on US, mosaic appearance of the lesion and pulsatile wave form in the portal vein on color Doppler US, conglomerated small nodular enhancement of the lesion and early appearance of the portal vein on CT, and a racemose network and early appearance of the portal vein on angiography. Five of the six patients underwent surgery, and all resected specimens were histologically found to be AVMs of the pancreas; however, one with developed portal hypertension at surgery died of repeated bleeding from esophageal varices. From analysis of total of 35 cases including our six cases, a mosaic appearance of the lesion was found in 100% and a pulsatile wave form in the portal vein in 77.8% on color Doppler US. Color Doppler US is noninvasive and useful for detecting congenital AVM of the pancreas at an early stage, preventing the portal hypertension causing esophageal varices and their rupture.

Adult↗
PubMed2001

Association of the shrinkage of uterine leiomyoma treated with GnRH agonist and deletion of long arm of chromosome 7.

Specific chromosomal abnormalities, such as del(7q), t(12;14), 12 trisomy, or the rearrangement of 6p, are seen in approximately 30% of uterine leiomyomas despite their benign status. We investigated the association between the shrinkage of uterine leiomyomas treated with a GnRH agonist and the interstitial deletion of chromosome 7q, which is one of the most common chromosomal abnormalities in uterine leiomyomas. This study covered 29 women with uterine leiomyomas who were treated with a GnRH agonist before surgery. The volume of the largest myoma nodule was measured by means of MRI before and at 12 weeks after the beginning of GnRH agonist treatment, and the percentage of the reduction in volume was calculated. Genomic DNA was extracted from leiomyoma tissue and peripheral blood, and amplified by PCR using fluorescently-tagged oligonucleotide primers of twelve microsatellite loci on chromosome 7. The PCR products were analyzed for loss of heterozygosity (LOH) using an automated fluorescent DNA sequencer. Of the 29 informative tumors, five (17%) showed LOH with deletion of the common region, D7S491. The mean percentages of the reduction in volume of the largest myomas with LOH or without LOH were 32+/-13 and 18+/-58%, respectively (not significant). One tumor showing interstitial deletion of both alleles (homo-deletion) reduced in volume by 19%. Another tumor showing an extraband increased in volume by 13%. Although tumor specific chromosomal deletion suggested the existence of tumor suppressor genes in this region, there was no significant association between the shrinkage of uterine leiomyomas treated with a GnRH agonist and the interstitial deletion of chromosome 7q.

Adult↗
PubMed2000

Quantitation of Fas and Fas ligand gene expression in human ovarian, cervical and endometrial carcinomas using real-time quantitative RT-PCR.

Alterations in the expression of Fas (CD95/APO-1) and its ligand (FasL) have been demonstrated in various types of cancers as a mechanism for tumour cell to escape from the immune system. In the present study, we evaluated the expression of the Fas and FasL genes in a wide range of primary gynaecological carcinomas. These included 31 ovarian, 29 cervical and 25 endometrial carcinoma tissues as well as four ovarian and three cervical carcinoma cell lines. Our real-time quantitative reverse transcription polymerase chain reaction analysis revealed that down-regulation of Fas expression is more prominent than the up-regulation of FasL expression in all types of gynaecological cancer studied. This down-regulation of Fas expression was also true for the seven carcinoma cell lines. Only one cervical carcinoma cell line, DoT, exhibited a high level of FasL expression. These results indicated that down-regulation of Fas expression is a common abnormality in many types of cancers including gynaecological cancers, whereas an increase in FasL expression is not a common phenomenon in these cancers.

Cervix Uteri↗
PubMed2000

Ovarian dysgerminoma with massive metastases to para-aortic lymph nodes.

We report on a 15-year-old female with left ovarian dysgerminoma accompanied by massive swelling of the para-aortic lymph nodes which was clearly demonstrated by preoperative magnetic resonance imaging (MRI). Metastasis to the para-aortic lymph nodes from dysgerminoma was confirmed by biopsies obtained during surgery. No study has previously reported dysgerminoma with massive para-aortic lymph node metastases clearly demonstrated by MRI. These preoperative MRI findings are presented here. The patient received six cycles of cisplatin-based combination chemotherapy with the BEP regimen (bleomycin, etoposide and cisplatin) after conservative surgery, and no residual para-aortic lymph nodes were detected by MRI or CT after the chemotherapy.

Adolescent↗
PubMed2000

Power Doppler sonography: evaluation of hepatocellular carcinoma after treatment with transarterial embolization or percutaneous ethanol injection therapy.

OBJECTIVE: The aim of this study was to compare tumor detectability by assessing the vascularity on power and color Doppler sonography and CT after transarterial embolization or percutaneous ethanol injection therapy or both in hepatocellular carcinoma. SUBJECTS AND METHODS: Forty-seven nodules of hepatocellular carcinoma (size, 28 +/- 7 mm [mean +/- standard deviation]; range, 20-40 mm) in 38 patients were treated with transarterial embolization (n = 6), percutaneous ethanol injection therapy (n = 23), and transarterial embolization plus percutaneous ethanol injection therapy (n = 9). Power Doppler sonography, color Doppler sonography, and CT were performed before and 2 weeks, 3 months, and 6 months after the treatments. The existence of hepatocellular carcinoma was confirmed by positive findings for color signals on both Doppler sonography techniques and for tumor stains on CT. All the tumors were determined to be malignant by microscopic examination of biopsy specimens. RESULTS: Before the treatments, power Doppler sonography (100%) and CT (100%) were significantly more effective than color Doppler sonography (61.7%) (p < 0.001, for both). Six months after the treatments, the sensitivity of power Doppler sonography (87.5%) was significantly better than that of color Doppler sonography (12.5%) but was not significant in comparison with CT (66.6%). However, power Doppler sonography detected color signals in two of three tumors in which iodized oil was accumulated and no tumor stain appeared on CT, and the two lesions detected with power Doppler sonography were carcinomas. CONCLUSION: Power Doppler sonography can be considered the most sensitive technique in assessing the viability of hepatocellular carcinoma treated with transarterial embolization or percutaneous ethanol injection therapy or both.

Adult↗
PubMed1999

Stimulus-coupled interaction of tyrosine hydroxylase with 14-3-3 proteins.

Tyrosine hydroxylase (TH) is phosphorylated by CaM kinase II and is activated in situ in response to a variety of stimuli that increase intracellular Ca(2+). We report here, using baculovirus-expressed TH, that the 14-3-3 protein binds and activates the expressed TH when the enzyme is phosphorylated at Ser-19, a site of CaM kinase II-dependent phosphorylation located in the regulatory domain of TH. Site-directed mutagenesis showed that a TH mutant in which Ser-19 was substituted by Ala retained enzymatic activity at the same level as the non-mutated enzyme, but was a poor substrate for CaM kinase II and did not bind the 14-3-3 protein. Likewise, a synthetic phosphopeptide (FRRAVpSELDA) corresponding to the part of the TH sequence, including phosphoSer-19, inhibited the interaction between the expressed TH and 14-3-3, while the phosphopeptide (GRRQpSLIED) corresponding to the site of cAMP-dependent phosphorylation (Ser-40) had little effect on complex formation. The complex was very stable with a dissociation constant of 3 nM. Furthermore, analysis of PC12nnr5 cells transfected with myc-tagged 14-3-3 showed that 14-3-3 formed a complex with endogenous TH when the cultured cells were exposed to a high K(+) concentration that increases intracellular Ca(2+) and phosphorylation of Ser-19 in TH. These findings suggest that the 14-3-3 protein participates in the stimulus-coupled regulation of catecholamine synthesis that occurs in response to depolarization-evoked, Ca(2+)-dependent phosphorylation of TH.

14-3-3 Proteins↗
PubMed1999

Complex formation of MukB, MukE and MukF proteins involved in chromosome partitioning in Escherichia coli.

mukF, mukE and mukB genes are essential for the process of chromosome partitioning in Escherichia coli. We have studied protein-protein interactions among MukB, MukE and MukF proteins by co-immunoprecipitation and sucrose gradient sedimentation experiments, using mukFEB null cells harboring plasmids carrying the wild-type or mutant-type mukFEB operon. MukB forms a complex with MukF and MukE. Analysis of mutant MukB proteins suggested that MukF and MukE bind the C-terminal globular domain of MukB. MukF is indispensable for an interaction between MukB and MukE; however, MukF itself is able to associate with MukB even in the absence of MukE. We have also found that MukF has a Ca(2+)-binding activity. Although purified MukF was able to make a complex either with MukE or MukB, a complex consisting of the three Muk proteins was barely detected in vitro. However, increasing the Ca(2+) or Mg(2+) concentration in the reaction partially restored complex formation. This suggests that Ca(2+) or Mg(2+) may be required for the formation of a complex consisting of the three Muk proteins, and thus may participate in a particular step during chromosome partitioning.

Amino Acid Sequence↗
PubMed1999

Influence of centriole behavior on the first spindle formation in zygotes of the brown alga Fucus distichus (Fucales, Phaeophyceae).

The influence of centrioles, derived from the sperm flagellar basal bodies, and the centrosomal material (MTOCs) on spindle formation in the brown alga Fucus distichus (oogamous) was studied by immunofluorescence microscopy using anti-centrin and anti-beta-tubulin antibodies. In contrast to a bipolar spindle, which is formed after normal fertilization, a multipolar spindle was formed in polyspermic zygote. The number of mitotic poles in polyspermic zygotes was double the number of sperm involved in fertilization. As an anti-centrin staining spot (centrioles) was located at these poles, the multipolar spindles in polyspermic zygotes were produced by the supplementary centrioles. When anucleate egg fragments were fertilized, chromosome condensation and mitosis did not occur in the sperm nucleus. Two anti-centrin staining spots could be detected, microtubules (MTs) radiated from nearby, but the mitotic spindle was never produced. When a single sperm fertilized multinucleate eggs (polygyny), abnormal spindles were also observed. In addition to two mitotic poles containing anti-centrin staining spots, extra mitotic poles without anti-centrin staining spots were also formed, and as a result multipolar spindles were formed. When karyogamy was blocked with colchicine, it became clear that the egg nucleus proceeded independently into mitosis accompanying chromosome condensation. A monoastral spindle could be frequently observed, and in rare cases a barrel-shaped spindle was formed. However, when a sperm nucleus was located near an egg nucleus, the two anti-centrin staining spots shifted to the egg nucleus from the sperm nucleus. In this case, a normal spindle was formed, the egg chromosomes arranged at the equator, and the associated MTs elongated from one pole of the egg spindle toward the sperm chromosomes which were scattered. From these results, it became clear that paternal centrioles derived from the sperm have a crucial role in spindle formation in the brown algae, such as they do during animal fertilization. However, paternal centrioles were not adequate for the functional centrosome during spindle formation. We speculated that centrosomal materials from the egg cytoplasm aggregate around the sperm centrioles and are needed for centrosomal activation.

Antibodies↗
PubMed1999

Confirmation of yessotoxin and 45,46,47-trinoryessotoxin production by Protoceratium reticulatum collected in Japan.

Two different strains of the dinoflagellate Protoceratium reticulatum collected at Harima Nada and Yamada Bay in Japan were cultured and analyzed by fluorometric HPLC for yessotoxin production. Only the Yamada Bay strain produced yessotoxin. The toxin together with its analog, 45,46,47-trinoryessotoxin, were isolated from larger scale culture and unambiguously confirmed by (1)H NMR and MS measurements. This is the first confirmation of the biogenetic origin of yessotoxin in Japan, where the toxin was first reported. The results also indicate that the production of yessotoxins by P. reticulatum differs from strain to strain, in a similar way to that observed in many other toxigenic dinoflagellates such as Dinophysis spp. and Alexandrium spp.

Animals↗