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Biomedical subjects

Hideaki Tanaka

Publications and source records attributed to Hideaki Tanaka.

At least 19 recordsLinked to original sources
PubMed2006

Expression of large tenascin-C splice variants by hepatic stellate cells/myofibroblasts in chronic hepatitis C.

BACKGROUND/AIMS: Earlier studies have suggested involvement of tenascin-C (TN-C) in liver fibrosis. Here, we examined expression of TN-C variants and types of alternatively spliced fibronectin-type III (FNIII) repeats in chronic hepatitis. METHODS: Using three monoclonal antibodies against TN-C variants, immunohistochemical staining was performed and the correlation with histological parameters of chronic hepatitis C was examined. The cellular source was also determined and variant expression and their types were tested using isolated rat hepatic stellate cells (HSCs), liver myofibroblasts, and/or LI90 cells. RESULTS: Large variants were not expressed in normal liver, but were up-regulated in chronic hepatitis, especially at sites of interface hepatitis and confluent necrosis, showing stronger correlations between staining intensity and these than with other parameters or fibrosis. TN-C deposition was closely correlated with increase in the number of alpha-smooth muscle actin-positive cells, i.e. activated HSCs/myofibroblasts, and in situ hybridization showed TN-C mRNA signals in the cells. Activated HSCs and myofibroblasts in culture highly expressed large variants of TN-C. In LI90 cells, sequencing of large variants revealed that the FNIII repeats D and A1/A4, followed by B, were preferentially included. CONCLUSIONS: TN-C and its variants are produced by HSCs/myofibroblasts, suggesting important roles in liver fibrogenesis.

Actins↗
PubMed2006

Hepatic oxidative DNA damage correlates with iron overload in chronic hepatitis C patients.

Hepatic oxidative stress occurs in chronic hepatitis C (CH-C), but little is known about its producing mechanisms and precise role in the pathogenesis of the disease. To determine the relevance of hepatic oxidatively generated DNA damage in CH-C, 8-hydroxy-2'-deoxyguanosine (8-OHdG) adducts were quantified in liver biopsy specimens by immunohistochemical staining, and its relationship with clinical, biochemical, and histological parameters, and treatment response was assessed in 40 CH-C patients. Hepatic 8-OHdG counts were significantly correlated with serum transaminase levels (r=0.560, p=0.0005) and histological grading activity (p=0.0013). Remarkably, 8-OHdG levels were also significantly related to body and hepatic iron storage markers (vs serum ferritin, r=0.565, p=0.0004; vs hepatic total iron score, r=0.403, p=0.0119; vs hepatic hepcidin messenger RNA, r=0.516, p=0.0013). Baseline hepatic oxidative stress was more prominent in nonsustained virological responder (non-SVR) than in SVR to interferon (IFN)/ribavirin treatment (50.8 vs 32.7 cells/10(5) microm2, p=0.0086). After phlebotomy, hepatic 8-OHdG levels were significantly reduced from 53.4 to 21.1 cells/10(5) microm2 (p=0.0125) with concomitant reductions of serum transaminase and iron-related markers in CH-C patients. In conclusion, this study showed that hepatic oxidatively generated DNA damage frequently occurs and is strongly associated with increased iron deposition and hepatic inflammation in CH-C patients, suggesting that iron overload is an important mediator of hepatic oxidative stress and disease progression in chronic HCV infection.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2006

Tsukushi cooperates with VG1 to induce primitive streak and Hensen's node formation in the chick embryo.

Three classes of signaling molecule, VG1, WNT and BMP, play crucial roles in axis formation in the chick embryo. Although VG1 and WNT signals have a pivotal function in inducing the primitive streak and Hensen's node in the embryo midline, their action is complemented by that of BMP antagonists that protect the prospective axial tissue from the inhibitory influence of BMPs secreted from the periphery. We have previously reported that a secreted factor, chick Tsukushi (TSK), is expressed in the primitive streak and Hensen's node, where it works as a BMP antagonist. Here, we describe a new crucial function for TSK in promoting formation of the primitive streak and Hensen's node by positively regulating VG1 activity. We provide evidence that TSK directly binds VG1 in vitro, and that TSK and VG1 functionally interact in axis formation, as shown by biological assays performed in chick and Xenopus embryos. Furthermore, we show that alternative splicing of TSK RNA leads to the formation of two isoforms (TSKA, originally designated as TSK, and TSKB) that differ in their C-terminal region. Biochemical and biological assays indicate that TSKB is a much weaker BMP antagonist than TSKA, although both isoforms efficiently interact with VG1. Remarkably, although both TSKA and TSKB are expressed throughout the early extending primitive streak, their expression patterns diverge during gastrulation. TSKA expression concentrates in Hensen's node, a well-known source of anti-BMP signals, whereas TSKB accumulates in the middle primitive streak (MPS), a region known to work as a node-inducing center where VG1 expression is also specifically localized. Loss-of-function experiments demonstrate that TSKB, but not TSKA, function is required in the MPS for induction of Hensen's node. Taken together, these results indicate that TSK isoforms play a crucial role in chick axis formation by locally modulating VG1 and BMP activities during gastrulation.

Alternative Splicing↗
PubMed2006

Morphology of hepatitis C and hepatitis B virus particles as detected by immunogold electron microscopy.

We performed indirect immunogold electron microscopy (EM) for immunological identification and characterization of hepatitis C virus (HCV). To clarify the morphology of HCV, an indirect immunogold EM of two plasma samples from patients with high HCV RNA titers was carried out using antibodies specific for the putative HCV envelope protein (E) 1. Spherical virus particles 55-65 nm in diameter with delicate spike projections were detected in the 1.14-1.16 g/ml fractions after sucrose density gradient centrifugation. Polyclonal and monoclonal antibodies to the putative HCV E1 specifically recognized these particles. In addition, immunogold EM of the samples was also performed to uncover the morphology of HCV core particles. Spherical particles 33-40 nm in diameter (average, 37 nm) were detected in the 1.22- to 1.25-g/ml fractions by conventional EM after sucrose density gradient centrifugation. Immunogold EM using rabbit polyclonal antibody (RR8) specific for the putative HCV core protein and colloidal gold-labeled goat antirabbit IgG showed binding of the gold particles with RR8. Some of the HCV core particles showed icosahedric morphology. Optical rotation technique showed that the HCV core particles exhibit sixfold symmetry and that the length of the regular hexagon side is approximately 20 nm, suggesting that they have an icosahedric structure. Further, the detection limit of the indirect immunogold EM was evaluated in 11 plasma samples from chronic hepatitis B patients with different degrees of hepatitis B virus (HBV) DNA titers using antihepatitis B surface antigen antibody. The study showed that the detection limit of virus using this method is 10(7) virions/ml.

DNA, Viral↗
PubMed2006

The ultrastructural morphology of native hepatitis B virus.

Cell lines (2.2.15 cells) capable of supporting the replication of hepatitis B virus (HBV) DNA and intact viral particles have been established by HBV DNA transfection into HepG2 cells. The purpose of this study was to determine the ultrastructural morphology of native HBV particles without purification in the culture supernatants and in sera from patients. Electron microscopy (EM) and immunogold EM of the samples were carried out using polyclonal and monoclonal anti-hepatitis B surface antigen antibodies. HBV particles in the purified samples from the culture supernatants by density-gradient centrifugation were examined to compare the morphology with that of unpurified samples. EM and immunogold EM studies demonstrated the presence of Dane particles (41.8 nm in diameter), cobra-shaped (head diameter, 42.4 nm), and horn-shaped (head diameter, 43.5 nm) particles in the culture supernatants and in the sera from two patients. The tail of the cobra-like particles had a diameter of 21.0 nm and a length of 214 nm. The hornlike particles had a long branch 20.1 nm in diameter with a length of 189 nm, and a short branch 21.4 nm in diameter with a length of 112 nm. The ratio of Dane particles and cobra- and horn-shaped particles in the supernatants was 5 : 4 : 1. After ultracentrifugation, the cobra- and horn-shaped particles completely disappeared; there were only Dane particles together with spheres of 22 nm and filaments. In conclusion, this study showed for the first time that the native replicative form of HBV is cobra- and horn-shaped.

Cell Line↗
PubMed2006

Circulating level of large splice variants of tenascin-C is a marker of piecemeal necrosis activity in patients with chronic hepatitis C.

BACKGROUND: It has been reported that histological activity index and piecemeal necrosis are good factors to evaluate the prognosis in patients with chronic hepatitis C (CHC). Thus, there is a need for simple and noninvasive means to assess disease activity and piecemeal necrosis in patients with CHC. In this study, we measured the serum concentrations of large splice variants of tenascin-C (cTN-C) in patients with CHC, and examined their correlation with the degree of inflammatory activity and fibrosis as evaluated in liver biopsy specimens. METHODS: The serum levels of cTN-C in 150 patients with CHC and 50 healthy volunteers were measured by enzyme-linked immunosorbent. The histology of liver biopsy specimens was also evaluated following the Desmet's grading/staging system and the Ishak's classification. Liver specimens obtained by biopsy were also immunohistochemically evaluated with anti-human tenascin-C antibodies. RESULTS: Serum cTN-C concentrations were significantly higher in CHC patients than in healthy volunteers (P < 0.0001). The levels of cTN-C showed no significant difference among the fibrosis stages as assessed by the Desmet's grading/staging system and Ishak's classification scores. However, the concentration of cTN-C was significantly correlated with the grade of activity. According to the Ishak's classification, the concentration of cTN-C was increased in proportion to the degree of piecemeal necrosis. Specific immunostaining of cTN-C was observed in limited areas of piecemeal necrosis but not in fibrotic areas. CONCLUSION: The measurement of serum levels of cTN-C is a useful marker of the activity of CHC, in particular of the degree of piecemeal necrosis.

Adult↗
PubMed2006

Expression and adhesive activity of SC1, an Ig superfamily cell adhesion molecule, in sporadic nephroblastomas of chicken.

SC1, an immunoglobulin superfamily cell adhesion molecule, is transiently expressed during avian embryogenesis by a variety of cell types. This molecule has a homophilic binding activity with SC1 itself and promotes neurite projection from embryonic neurons. However, the potential role of this molecule in pathologic tissue specimens from chickens has yet to be elucidated. In this study, we examined the expression and functional role of SC1 in the sporadic nephroblastomas of chickens. Western blot analysis showed SC1 to be recognized as approximately 100 kDa and enriched in embryonic metanephros with a lower level in the adult kidney, while it was overexpressed in nephroblastomas. Immunohistochemically, SC1 was abundantly found in the tubular epithelia and blastemal cells of embryonic metanephros. In contrast, it had almost completely disappeared in the adult kidney; parts of the distal convoluted and intermediated tubules, collecting ducts, and Bowman's capsule slightly expressed SC1. In all 32 cases of nephroblastoma, SC1 was overexpressed in most characteristic components in tumors such as neoplastic epithelia with various types of differentiation, blastemal cell condensations, and glomeruloid bodies. Primary culture cells from a nephroblastoma expressed SC1 on the cell surface, whereas cells from the adult kidney showed only weak expression. A cell aggregation assay revealed that the dissociated cells from a nephroblastoma have strong aggregation activity, which was inhibited by anti-SC1 antibody. In contrast, the self-aggregation of adult chicken kidney cells was weaker than that of the tumor and not inhibited by the antibody. These findings suggest that the expression of SC1 might play a potential role in both the structural formation of nephroblastomas, based on its adhesive activity, and normal renal development.

Activated-Leukocyte Cell Adhesion Molecule↗
PubMed2006

[A case of aseptic meningitis caused by relapsing polychondritis].

We report a patient of relapsing polychondritis (RP) with antecedent aseptic meningitis. A 65-year-old man has developed headache and fever. Neurological examination showed meningeal signs, and cerebrospinal fluid (CSF) examination revealed meningeal inflammation which contained 450 polymorphonuclear cells/microl, 302 mononuclear cells/microl, and 0 red cells/microl, with 79 mg protein/dl. Serologic testing for autoimmune disease as well as the culture and cytology of CSF were negative. He admitted our hospital as having aseptic meningitis and experienced antibiotic therapy. However, his pyrexia continued and he developed repeating visual and hearing impairment reacting to steroid. Three months later, he became behaviorally deaf, and bilateral auricular chondritis occurred with nonerosive seronegative inflammatory polyarthritis. The result of condral biopsy was consistent with the diagnosis of RP showing cartilage surrounded by an intense inflammatory cell response with a decreased number of chondrocytes. A clinical diagnosis was made and prednisolone 60 mg/day was begun with the result of resolution of the auricular chondritis, and slight improvement of his deafness. Aseptic meningitis is a rare complication of RP. Only one report detailed RP patient who had preceding meningitis. RP is a potentially lethal disease resulting from suffocation by airway collapse, the complications of a cardiac large vessel, and so on. For improvement of a life prognosis, an early diagnosis and treatment are indispensable. Although RP is a rare discovery, it is necessary that RP should be taken into consideration and be differentiated as a cause of relapsing aseptic meningitis.

Aged↗
PubMed2006

Morphological identification of hepatitis C virus E1 and E2 envelope glycoproteins on the virion surface using immunogold electron microscopy.

It is known that hepatitis C virus (HCV) particles are spherical, 55-65 nm particles with fine surface projections of about 6 nm in length and with a 30-35 nm inner core. We have reported that free HCV particles labeled with gold particles specific to the HCV E1 glycoprotein are located in 1.14-1.16 g/ml fractions from plasma samples with high HCV RNA titers after sucrose density gradient centrifugation. However, the morphology of the HCV E2 glycoprotein on the virion has not yet been elucidated. To visualize HCV E2 localization on the virion, we used the same plasma samples where HCV particles were clearly shown. An indirect immunogold electron microscopic study was carried out using monoclonal and polyclonal anti-HCV E2 antibodies. HCV-like particles specifically reacted with the anti-HCV E2 antibodies. Moreover, to evaluate the localization of the HCV E1 and E2 glycoproteins on the virion surface, an immunogold electron microscopic study using double labeling with anti-HCV E1 antibodies and anti-HCV E2 antibodies was also performed. These particles also specifically reacted with both anti-E1 and E2 antibodies. This is the first report showing the presence of both HCV E1 and E2 glycoproteins on HCV virion surface in human plasma samples.

Hepacivirus↗
PubMed2005

The LRR and Ig domain-containing membrane protein SST273 is expressed on motoneurons.

We performed signal sequence trap cDNA cloning using a cDNA library of enriched chicken embryonic spinal motoneurons and identified a novel transmembrane molecule, SST273 (Signal Sequence Trap clone 273). SST273 has five leucine-rich repeats (LRRs) and one immunoglobulin (Ig) domain in its extracellular domain. The human (KIAA1465) and mouse (BC059068) homologues of SST273 were already cloned, but had not yet been analyzed. The amino acid homologies between chick SST273 and human or mouse homologue are 52.1 and 51.5%, respectively. SST273 mRNA and its protein product were uniquely expressed in the embryonic spinal and cranial motoneurons at early developmental stages.

Amino Acid Sequence↗
PubMed2005

Tsukushi controls ectodermal patterning and neural crest specification in Xenopus by direct regulation of BMP4 and X-delta-1 activity.

In Xenopus, ectodermal patterning depends on a mediolateral gradient of BMP signaling, higher in the epidermis and lower in the neuroectoderm. Neural crest cells are specified at the border between the neural plate and the epidermis, at intermediate levels of BMP signaling. We recently described a novel secreted protein, Tsukushi (TSK), which works as a BMP antagonist during chick gastrulation. Here, we report on the Xenopus TSK gene (X-TSK), and show that it is involved in neural crest specification. X-TSK expression accumulates after gastrulation at the anterior-lateral edges of the neural plate, including the presumptive neural crest region. In gain-of-function experiments, X-TSK can strongly enhance neural crest specification by the dorsolateral mesoderm or X-Wnt8 in ectodermal explants, while the electroporation of X-TSK mRNA in the lateral ectoderm of embryos after gastrulation can induce the expression of neural crest markers in vivo. By contrast, depletion of X-TSK in explants or embryos impairs neural crest specification. Similarly to its chick homolog, X-TSK works as a BMP antagonist by direct binding to BMP4. However, X-TSK can also indirectly regulate BMP4 mRNA expression at the neural plate border via modulation of the Delta-Notch signaling pathway. We show that X-TSK directly binds to the extracellular region of X-delta-1, and modulates Delta-dependent Notch activity. We propose that X-TSK plays a key role in neural crest formation by directly regulating BMP and Delta activities at the boundary between the neural and the non-neural ectoderm.

Animals↗
PubMed2005

MN-cadherin and its novel variant are transiently expressed in chick embryo spinal cord.

To isolate cDNAs that are involved in limb-motoneuron development, we compared mRNAs of lumbar and thoracic motoneurons purified from spinal cord of E4 chick embryo by differential display. In situ hybridization demonstrated that one of cDNAs is expressed exclusively in lateral motor column in spinal cord from E4 to E10. We identified two mRNA variants for the cDNA by library screening. The long form (788 amino acids) was identical to chick MN-cadherin. The short variant (543 amino acids) lacks the first two of five extracellular domains of MN-cadherin, which commonly exist in classical cadherins. The amino acid sequence of the short form is identical to that of the carboxyl terminal MN-cadherin, except for the distinct signal sequence. The ratio of mRNA of short form to long form was 1-20. cDNA transfection study revealed that the long form but not the short form MN-cadherin had cell adhesion activity.

Amino Acid Sequence↗