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Biomedical subjects

N Taniguchi

Publications and source records attributed to N Taniguchi.

At least 343 records · Page 19Linked to original sources
PubMed1994

Selective suppression of N-acetylglucosaminyltransferase III activity in a human hepatoblastoma cell line transfected with hepatitis B virus.

UDP-N-acetylglucosamine: beta-D-mannoside beta-1,4-N-acetylglucosaminyl-transferase III (GnT-III) is a key enzyme in the branching of asparagine-linked oligosaccharides, which are present in surface membrane proteins of various tissues and in secretory glycoproteins. The activity of GnT-III was assayed in 2 human hepatoblastoma cell lines, Huh6, which was the parental cell line, and HB611, which was established by transfection of 3 tandem copies of the hepatitis B virus genome into Huh6. A significant difference in GnT-III activity was found between Huh6 and HB611 (136 +/- 18.3 pmol/h/mg versus 6.7 +/- 2.4 pmol/h/mg; mean +/- SD, P < 0.001), whereas levels of the glycosyltransferases alpha-3-D-mannoside beta-1,4-N-acetylglucosaminyltransferase IV, alpha-6-D-mannoside beta-1,6-N-acetylglucosaminyltransferase-V, and beta-1,4-galactosyltransferase were almost the same in both cell lines. Northern blot analysis indicated that the decreased activity of GnT-III in HB611 was due to the decreased transcript. When HB611 was treated with interferon-alpha, expression of hepatitis B virus-related mRNA decreased, and the activity of GnT-III increased from 8.5 +/- 3.8 to 22.0 +/- 7.2 pmol/h/mg (mean +/- SD, P < 0.05). This increase was not found in Huh6. Binding capacity with erythrocyte phytohemagglutinin in these cells using fluorescence-activated cell sorter analysis was different, suggesting that the structure of sugar chain on the cell surface might be altered by suppression of GnT-III activity. This is the first report that hepatitis B virus selectively suppressed the GnT-III activity in hepatoblastoma cells.

Blotting, Northern↗
PubMed1994

Heparin-binding EGF-like growth factor is a potent mitogen for rat hepatocytes.

We examined the hepatotrophic activity of heparin-binding EGF-like growth factor (HB-EGF), a recently identified potent mitogen for vascular smooth muscle cells and fibroblasts. HB-EGF stimulated DNA synthesis of rat hepatocytes in primary culture in a dose-dependent manner up to 30 ng/ml. The maximal stimulation by HB-EGF represented more than 80% of that induced by HGF. In normal rat liver, the transcript of HB-EGF gene was detected in the non-parenchymal cells and very low level in the hepatocytes. In the regenerating liver on the 3rd day after 70% hepatectomy, the HB-EGF mRNA increased in the non-parenchymal cells, suggesting that HB-EGF may contribute to liver regeneration through a paracrine mechanism.

Animals↗
PubMed1994

cDNA cloning and chromosomal mapping of human N-acetylglucosaminyltransferase V+.

Human N-acetylglucosaminyltransferase V (GnT-V, EC 2.4.1.155) cDNA was isolated from a human fetal liver cDNA library. Oligonucleotide primers for polymerase chain reaction were designed according to the amino acid sequence of human GnT-V. Screening for the cDNA was carried out by plaque hybridization using PCR products of about 500 bp. Human GnT-V has 741 amino acids and six putative N-glycosylation sites. The homology to rat GnT-V is 88% at the nucleotide level and is 97% at the amino acid level, and there is one amino acid insertion. Using the cDNA clones as probe, five overlapping genomic clones have been isolated from a human phagemid DNA library. The GnT-V gene has been mapped to chromosome 2q21 using fluorescence in situ hybridization.

Amino Acid Sequence↗
PubMed1994

Ionizing radiation induces apoptotic cell death in human TcR-gamma/delta+ T and natural killer cells without detectable p53 protein.

The p53 tumor suppressor gene has been shown to be involved in programmed cell death, apoptosis, in murine immature thymocytes after treatment with ionizing radiation. Ionizing radiation also induces apoptosis in peripheral mature lymphocytes. In this work, we investigated the p53 participation in radiation-induced apoptosis in human peripheral blood lymphocytes (PBL) subpopulations. Exposure to gamma-irradiation resulted in an appreciable induction of apoptotic cell death in TcR-alpha/beta+ (CD4+ and CD8+) T cells, TcR-gamma/delta+ T cells, B cells and natural killer (NK) cells, as assessed by DNA fragmentation as well as the morphological characteristics. Importantly, it was found that there was a marked difference among PBL subpopulations as regards the induction of p53 protein by gamma-irradiation. Similar to previous observations for murine thymocytes, p53 induction in TcR-alpha/beta+ T cells and B cells after gamma-irradiation was evident by Western blot analysis. Radiation-induced apoptosis in TcR-alpha/beta+ T cells and B cells was efficiently inhibited by cycloheximide, indicating the requirement of de novo protein synthesis, including p53 protein, for radiation-induced apoptosis in both subpopulations. In marked contrast, no identifiable levels of p53 protein were induced in either TcR-gamma/delta+ T or NK cells after gamma-irradiation. In addition, it was demonstrated that radiation-induced cell death in TcR-gamma/delta+ T and NK cells could be prevented by interleukin-2, but not by cycloheximide. These results imply that radiation-induced lymphocytic apoptosis can be mediated by p53-dependent or -independent mechanisms.

Adult↗
PubMed1994

Bone-forming ability of 24R,25-dihydroxyvitamin D3 in the hypophosphatemic mouse.

To determine whether 24R,25-dihydroxyvitamin D3 [24R,25(OH)2D3] exerts unique biologic effects on bone, we examined the effects of the vitamin D metabolites, 24R,25(OH)2D3 and 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3], on the hypophosphatemic (Hyp) mouse, a model for X-linked hypophosphatemic rickets in humans. The Hyp mice were administered 1-10,000 micrograms/kg/day of 24R,25(OH)2D3, 0.01-10 micrograms/kg/day of 1 alpha,25(OH)2D3, or vehicle alone, given daily for 28 days by intraperitoneal injection. 24R,25(OH)2D3 at doses of 1-1000 micrograms/kg/day had dose-dependent effects in increasing bone size, dry bone weight, and bone mineral content without causing hypercalcemia. 1 alpha,25(OH)2D3 at doses of 1 or 10 micrograms/kg/day, which we considered to have activity similar to that of 1000 micrograms/kg/day of 24R,25(OH)2D3 with respect to cell differentiation activity, caused severe bone resorption and hypercalcemia. At 0.1 microgram/kg/day, 1 alpha,25(OH)2D3 increased bone size, similarly to a dose of 1000 micrograms/kg/day of 24R,25(OH)2D3, without significantly affecting dry bone weight or bone mineral content, as did 1000 micrograms/kg/day of 24R,25(OH)2D3. These findings suggest that 24R,25(OH)2D3 exerts unique activity in the Hyp mouse rather than merely mimicking the activity of 1 alpha,25(OH)2D3.

Animals↗
PubMed1994

Oxidative stress induced by intermittent exposure at a simulated altitude of 4000 m decreases mitochondrial superoxide dismutase content in soleus muscle of rats.

The effects were examined of 6-month intermittent hypobaric (4000 m) exposure on the antioxidant enzyme systems in soleus and tibialis muscles of rats. At the end of the 6-month experimental exposure, the six rats in both the exposed group and the control group were sacrificed. Immunoreactive mitochondrial superoxide dismutase (Mn-SOD) contents were measured as well as the activities of antioxidant enzymes [Mn-SOD, cytosolic SOD (Cu,Zn-SOD), catalase (CAT), and glutathione peroxidase (GPX)]. Thiobarbituric acid-reactive substances (TBARS) were also determined as an indicator of lipid peroxidation. The high altitude exposure resulted in a marked increase in TBARS content in soleus muscle, suggesting increased levels of oxygen free radicals. Conversely, significant decreases in both Mn-SOD content and activity in soleus muscle were noted after exposure. Such trends were not noticed in tibialis muscle. On the other hand, no significant changes in Cu,Zn-SOD, CAT, or GPX were observed in either muscle. These results suggested that the increases in lipid peroxidation were most probably a result of decreased Mn-SOD function which was more depressed in oxidative than in glycolytic muscle.

Altitude↗
PubMed1994

Immunohistochemical expression of manganese superoxide dismutase in hepatocellular carcinoma, using a specific monoclonal antibody.

The expression of manganese superoxide dismutase (Mn-SOD) was studied immunohistochemically, using a specific monoclonal antibody, in surgically resected hepatocellular carcinoma (HCC) and noncancerous tissues from 47 patients (2 with well-differentiated HCC, 36 with moderately differentiated HCC, 8 with poorly differentiated HCC, and 1 with undifferentiated carcinoma). Cancer cells in 44 patients (93.6%) were positive for Mn-SOD. The staining pattern of cancer cells was mostly homogeneous in well-differentiated HCC, whereas it was heterogeneous in poorly differentiated HCC. Moreover, strongly positive immunoreactivity was observed in noncancerous liver tissues in all patients, especially in normal hepatocytes surrounding HCC, regenerative small hepatocytes in the tumor boundary, and mononuclear inflammatory cells in the necroinflammatory lesions. The positive immunoreactivity for Mn-SOD in patients with HCC appears to reflect increased production of the enzyme protein.

Adult↗
PubMed1994

Expression of heparin-binding epidermal growth factor in human hepatocellular carcinoma.

BACKGROUND/AIMS: Growth factors are involved in the development and progression of cancer. The purpose of this study was to evaluate the possible role of heparin-binding epidermal growth factor-like growth factor (HB-EGF), which is a member of the EGF family, in the neoplastic transformation of hepatocytes. METHODS: Gene expression and protein production of HB-EGF were investigated in samples of human hepatocellular carcinoma (HCC) from 17 patients using Northern hybridization and immunohistochemical methods. RESULTS: The amount of HB-EGF messenger RNA was increased in the patients' HCC specimens compared with the surrounding liver tissues. In noncancerous hepatic tissues, HB-EGF was faintly positive in hepatocytes. Immunoreactive HB-EGF-producing cells were identified in HCC cells of all 17 patients with HCC, indicating that HB-EGF was produced in HCC cells themselves. However, none of the specimens from 10 patients with metastatic adenocarcinoma in the liver was positive for HB-EGF. The EGF receptor, which binds to HB-EGF, was also expressed on HCC cells. CONCLUSIONS: It is hypothesized that the enhanced expression of immunoreactive HB-EGF on the cell suggests a possible role of HB-EGF in the development or progression of human HCC in an autocrine and/or a juxtacrine manners.

Adult↗
PubMed1994

Nitric oxide synthase from rat colorectum: purification, peptide sequencing, partial PCR cloning, and immunohistochemistry.

Nitric oxide synthase (NOS) has been purified over 6,500-fold with a 3.4% yield from rat colorectum with 2',5'-ADP-Sepharose, DEAE cellulose, and gel filtration. The purified enzyme gave a single band corresponding to an apparent molecular mass of 160 Dka on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. When assayed in the requisite presence of L-arginine, CaCl2, NADPH, calmodulin, tetrahydro-L-biopterin, and FAD, the purified enzyme exhibited a specific activity of 328 nmol/min/mg L-citrulline formed and an apparent Km for L-arginine of 2.9 microM. Amino acid sequencing of 12 peptides revealed identical sequences to that of the neuronal type enzyme except for two altered amino acid residues. When partial reverse transcription-polymerase chain reaction of RNA from rat colorectum and cerebellum was performed using primers designed according to the amino acid sequences determined, these amino acid changes were found in both cDNA fragments, indicating the identity of the colorectal enzyme to the cerebellar one. A polyclonal antibody raised against NOS purified from rat cerebellum cross-reacted with the NOS from colorectum but not that from IFN-gamma stimulated macrophage-derived cells, RAW 264.7. Immunohistochemical analysis of the colorectum using this specific antibody indicated that Auerbach's plexus is strongly immunoreactive, supporting the hypothesis that NO is an inhibitory transmitter for non-adrenergic and non-cholinergic nerves in the colorectum.

Amino Acid Oxidoreductases↗
PubMed1994

Mature helper T cell requirement for immunoglobulin production by neonatal native B cells injected intraperitoneally into severe combined immunodeficient (SCID) mice.

It is accepted that human neonatal naive B cells produce mainly IgM in vivo as well as in vitro. Our previous work has demonstrated that i.p. injection of neonatal B cells together with adult mature T cells induces substantial levels of human IgG in the serum of SCID recipient mice. The present study was further attempted to determine the cellular components required for immunoglobulin production by neonatal B cells in SCID mice. When neonatal B and adult T cells were transferred into the SCID mice, human immunoglobulins, largely of IgG, were maximally detected in the serum around 6 weeks after a cell transfer. Depletion of CD4+ T cells from adult T cells resulted in undetectable levels of human immunoglobulin in the serum. By contrast, CD4+ T cell-enriched populations exhibited an enhancing effect on immunoglobulin production by neonatal B cells. Higher levels of immunoglobulin, including IgA and IgM, were detected in the peritoneal fluid than in the serum as early as 2 weeks after the cell transfer. Human T cells expressing activation antigens such as CD45RO and HLA-DR antigens were identified in the peritoneal lavages. These results suggest that neonatal naive B cells are able to differentiate into cells producing all classes of immunoglobulin in the presence of mature CD4+ T cells in a SCID mouse environment. The peritoneal cavity of SCID mice appears to provide a suitable place for immune responses by human cells, possibly in association with a certain xenogeneic reaction.

Adult↗
PubMed1994

Acute thrombocytopenic purpura associated with primary Epstein-Barr virus infection.

Acute idiopathic thrombocytopenic purpura (ITP) often appears to be related to the sensitization by some viral infections. However, the causative viral agents are not identified in most cases. Although the primary infection with Epstein-Barr virus (EBV) occurs during early childhood in Japan, the majority of cases are usually asymptomatic. A minority are associated with acute infectious mononucleosis (IM), which is characterized by fever, tonsillitis, lymphadenopathy, splenomegaly and liver dysfunction. In this report, three cases are described of children with EBV-induced ITP who clinically had atypical findings of IM. Their primary EBV infections were confirmed by serological test and, in addition, were verified by the enhanced expression of activation antigens (HLA-DR and CD45RO) on T cells as well as the inverted ratio of CD4+ to CD8+ subsets. These observations imply that ITP can occur as one of the host responses during primary EBV infections, irrespective of clinical manifestations. Evaluation of lymphocyte subpopulations may be useful for the assessment of primary EBV infection in ITP.

Acute Disease↗
PubMed1994

Kawasaki disease with a concomitant primary Epstein-Barr virus infection.

A two year old boy exhibited not only clinical manifestations which suggested a recurrence of Kawasaki disease (KD) but also evidence of a primary infection by Epstein-Barr virus (EBV) including tonsillitis, splenomegaly and atypical lymphocytosis in the peripheral blood. An inverted CD4/CD8 ratio in lymphocyte subsets suggested the presence of infectious mononucleosis (IM). Epstein-Barr virus titers (viral capsid antigen-immunoglobulin G 1:20; Epstein-Barr virus-associated nuclear antigen < 1:10) showed an acute EBV infection and the presence of EBV genome in the blood was determined by the polymerase chain reaction technique. In Japan, the peak incidence of KD and IM is in children under 4 years of age. From the investigation of EBV titers, it has been reported that some patients with KD develop an associated, unusual primary EBV infection. Kawasaki disease concurrent with a primary EBV infection as in this case, suggests the possibility of an etiologic agent related to the KD rather than to the EBV infection itself.

Child, Preschool↗
PubMed1994

Influence of RF capacitive heating on the alpha 1-adrenergic receptors of rat prostates.

The aim of this study was to find out the influence of radiofrequency (RF) capacitive heating on the alpha 1-adrenergic receptor of rat prostates. The prostates of 30-week-old Wistar rats were submitted to a 1-hour single session of RF capacitive heating at 45 degrees C. The ventral prostates that were submitted to heating were compared to those of other rats that were not submitted to heating. In order to determine the density of alpha 1-adrenergic receptors in rat ventral prostates, binding assays for alpha 1-adrenergic receptor were performed with [3H]prazosin in membrane preparations. The receptor density in the control group was 27.07 +/- 3.75 fmol/mg protein. The alpha 1-adrenergic receptor density (Bmax) in the thermotherapy group was 17.91 +/- 5.15 fmol/mg protein. A remarkable decrease in the density of alpha 1-adrenergic receptors was observed in the rat prostates of the thermotherapy group. In conclusion, the present results demonstrate that heating the rat prostate by RF capacitive heating damages the alpha 1-adrenergic receptors.

Animals↗
PubMed1994

Lung manganese superoxide dismutase increases during cytokine-mediated protection against pulmonary oxygen toxicity in rats.

Parenteral injection of the cytokines interleukin-1 and tumor necrosis factor, or of endotoxin (lipopolysaccharide), protects rats against lethal pulmonary oxygen toxicity. To determine the potential importance of manganese superoxide dismutase (MnSOD) in this model, we measured MnSOD mRNA and activity in lung. In addition, we confirmed that increases in activities were related to changes in MnSOD protein, which was measured using an enzyme-linked immunosorbentassay (ELISA) technique. After cytokine or endotoxin administration, increases in lung MnSOD mRNA occurred promptly (4 h), with or without hyperoxic exposure. In parallel, lung MnSOD protein and activity were increased after 24 h, and protein levels remained elevated after 52 h. MnSOD activity and protein levels were closely correlated. Neither lung copper-zinc superoxide dismutase (CuZnSOD) mRNA nor activity increased following administration of cytokines. Small increases in CuZnSOD mRNA, which did not exceed those in beta-actin mRNA, occurred early (4 h) after endotoxin, but CuZnSOD activity was unchanged. Immunohistochemistry was used to demonstrate in which cell types the increase in MnSOD protein occurred after cytokine or endotoxin administration. In agreement with ELISA findings, immunoreactive MnSOD appeared to be increased in lung parenchyma, but not in lung neutrophils, 24 h after cytokine or endotoxin treatment. MnSOD was heavily concentrated in alveolar type II cells. However, the numbers of surfactant protein D-positive (type II) cells in lung sections did not appear to be increased after treatment with cytokines or endotoxin. We conclude that early and sustained increases in endogenous MnSOD, but not CuZnSOD or other antioxidant enzymes, are associated with protection of rat lungs against hyperoxic damage by cytokines or endotoxin.

Actins↗
PubMed1994

Induction of manganese superoxide dismutase in rat cardiac myocytes increases tolerance to hypoxia 24 hours after preconditioning.

Manganese superoxide dismutase (Mn-SOD) is induced in ischemic hearts 24 h after ischemic preconditioning, when tolerance to ischemia is acquired. We examined the relationship between Mn-SOD induction and the protective effect of preconditioning using cultured rat cardiac myocytes. Exposure of cardiac myocytes to brief hypoxia (1 h) decreased creatine kinase release induced by sustained hypoxia (3 h) that follows when the sustained hypoxia was applied 24 h after hypoxic preconditioning (57% of that in cells without preconditioning). The activity and content of Mn-SOD in cardiac myocytes were increased 24 h after hypoxic preconditioning (activity, 170%; content, 139% compared with cells without preconditioning) coincidentally with the acquisition of tolerance to hypoxia. Mn-SOD mRNA was also increased 20-40 min after preconditioning. Antisense oligodeoxyribonucleotides corresponding to the initiation site of Mn-SOD translation inhibited the increases in the Mn-SOD content and activity and abolished the expected decrease in creatine kinase release induced by sustained hypoxia after 24 h of hypoxic preconditioning. Sense oligodeoxyribonucleotides did not abolish either Mn-SOD induction or tolerance to hypoxia. These results suggest that the induction of Mn-SOD in myocytes by preconditioning plays a pivotal role in the acquisition of tolerance to ischemia at a later phase (24 h) of ischemic preconditioning.

Adaptation, Physiological↗