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Junko Tanaka

Publications and source records attributed to Junko Tanaka.

At least 37 records · Page 2Linked to original sources
PubMed2004

Titration of hepatitis C virus in chimpanzees for determining the copy number required for transmission.

OBJECTIVE: To determine the copy number of hepatitis C virus (HCV) RNA, determined by nucleic acid amplification test (NAT) for screening blood units in Japan, that can transmit infection to chimpanzees. METHODS: Fresh-frozen plasma with markers of HCV infection, as well as inocula pedigreed from 1 of them, were evaluated for the infectious activity in chimpanzees. RESULTS: One unit each (273-282 ml) of fresh-frozen plasma from 2 blood donors or a pool from 13 donors to make a unit, which contained high-titered antibody to HCV but without HCV RNA detectable by NAT, did not infect any of 3 chimpanzees. Two chimpanzees were infected, however, when they were inoculated with 1 ml of serum from a blood donor in the 'window period' of HCV infection and containing 7.0 x 10(6) copies/ml of HCV RNA. The preacute phase serum from 1 of them harvested 7 weeks after the inoculation was titrated in 2 chimpanzees, and an inoculum containing approximately 2 x 10(1) copies of HCV RNA could transmit infection to both of them. CONCLUSION: Approximately 20 copies of HCV can transmit infection to recipients, which needs to be taken into consideration in planning the screening of blood units for HCV RNA by NAT. Although the sensitivity of present NAT could be improved further, there would be a limit of it in detecting a low-level HCV RNA in the window period of donors with the infectious capacity in recipients.

Animals↗
PubMed2004

Using a customized DNA microarray for expression profiling of the estrogen-responsive genes to evaluate estrogen activity among natural estrogens and industrial chemicals.

We developed a DNA microarray to evaluate the estrogen activity of natural estrogens and industrial chemicals. Using MCF-7 cells, we conducted a comprehensive analysis of estrogen-responsive genes among approximately 20,000 human genes. On the basis of reproducible and reliable responses of the genes to estrogen, we selected 172 genes to be used for developing a customized DNA microarray. Using this DNA microarray, we examined estrogen activity among natural estrogens (17beta-estradiol, estriol, estrone, genistein), industrial chemicals (diethylstilbestrol, bisphenol A, nonylphenol, methoxychlor), and dioxin. We obtained results identical to those for other bioassays that are used for detecting estrogen activity. On the basis of statistical correlations analysis, these bioassays have shown more sensitivity for dioxin and methoxychlor.

Biological Assay↗
PubMed2004

[A national project for the management of viral hepatitis toward prevention of hepatocellular carcinoma in Japan].

Annual incidence of hepatocellular carcinoma (HCC) keeps increasing during the past 30 years in Japan, most of which represents the end-stage disease of persistent infection with hepatitis C virus (HCV). To cope with this dire situation, a 5-year national project was launched since April 2002 for the management of viral hepatitis toward eventual prevention of HCC in Japan. This project is based on robust data on the epidemiology of chronic hepatitis and HCC induced by persistent HCV infection that have gained in the past 10 years by untiring efforts. It has been thrust by rapid advancement in diagnosis and treatment of HCC, and is targeted on the Japanese aged 40 years or older who are at increased risk of developing HCC. Further efforts are required to arouse concerns and attract commitment in the public, for an increased compliance to screening. At the same time, the national system has to be worked out for following up HCV carriers for immediate treatment of those who are found with liver disease.

Adolescent↗
PubMed2003

In vitro heparan sulfate polymerization: crucial roles of core protein moieties of primer substrates in addition to the EXT1-EXT2 interaction.

Heparan, the common unsulfated precursor of heparan sulfate (HS) and heparin, is synthesized on the glycosaminoglycan-protein linkage region tetrasaccharide GlcUA-Gal-Gal-Xyl attached to the respective core proteins presumably by HS co-polymerases encoded by EXT1 and EXT2, the genetic defects of which result in hereditary multiple exostoses in humans. Although both EXT1 and EXT2 exhibit GlcNAc transferase and GlcUA transferase activities required for the HS synthesis, no HS chain polymerization has been demonstrated in vitro using recombinant enzymes. Here we report in vitro HS polymerization. Recombinant soluble enzymes expressed by co-transfection of EXT1 and EXT2 synthesized heparan polymers with average molecular weights greater than 1.7 x 105 using UDP-[3H]GlcNAc and UDP-GlcUA as donors on the recombinant glypican-1 core protein and also on the synthetic linkage region analog GlcUA-Gal-O-C2H4NH-benzyloxycarbonyl. Moreover, in our in vitro polymerization system, a part time proteoglycan, alpha-thrombomodulin, that is normally modified with chondroitin sulfate served as a polymerization primer for heparan chain. In contrast, no polymerization was achieved with a mixture of individually expressed EXT1 and EXT2 or with acceptor substrates such as N-acetylheparosan oligosaccharides or the linkage region tetrasaccharide-Ser, which are devoid of a hydrophobic aglycon, suggesting the critical requirement of core protein moieties in addition to the interaction between EXT1 and EXT2 for HS polymerization.

Animals↗
PubMed2003

Determination of endogenous peptides in the porcine brain: possible construction of peptidome, a fact database for endogenous peptides.

Peptides play crucial roles in many physiological events. However, a database for endogenous peptides has not yet been developed, because the peptides are easily degraded by proteolytic enzymes during extraction and purification. In this study, we demonstrated that the data for endogenous peptides could be collected by minimizing the proteolytic degradation. We separated porcine brain peptides into 5250 fractions by 2-dimensional chromatography (first ion-exchange and second reversed-phase high-performance liquid chromatography), and 75 fractions of average peptide contents were analyzed in detail by mass spectrometers and a protein sequencer. Based on the analysis data obtained in this study, more than 10000 peptides were deduced to be detected, and more than 1000 peptides to be identified starting from 2 g of brain tissue. Thus, we deduce that it is possible to construct a database for endogenous peptides starting from a gram level of tissue by using 2-dimensional high-performance liquid chromatography coupled with a mass spectrometer.

Amino Acid Sequence↗
PubMed2003

Natural histories of hepatitis C virus infection in men and women simulated by the Markov model.

The Markov model was introduced to simulate natural histories of hepatitis C virus (HCV) infection in men and women. The data set was constructed on 942 HCV carriers who were examined at least once a year without receiving antiviral therapies. Based on 2,251 patient-year data, the probabilities of transition between any two of the four clinical states, i.e., asymptomatic carrier state, chronic hepatitis, liver cirrhosis and hepatocellular carcinoma in 1 year were calculated. Hepatocellular carcinoma was defined as the absorbing state from where no transitions occur. Probability matrices thus obtained on six each subsets of HCV infection (asymptomatic carrier state, chronic hepatitis and liver cirrhosis in men and women) in their forties, fifties, and sixties, were used to simulate long-term outcomes of HCV infection. Male asymptomatic carriers aged 40 years were expected to retain the asymptomatic carrier state in 2.6%, evolve into chronic hepatitis in 48.4%, liver cirrhosis in 14.6% and hepatocellular carcinoma in 34.4% after 30 years when they reached 70 years of age, in contrast to 1.9%, 45.3%, 32.8% and 20.0%, respectively, of female asymptomatic carriers. Likewise, male patients with chronic hepatitis aged 40 years were expected to remain with chronic hepatitis in 43.8%, evolve into liver cirrhosis in 15.0% and hepatocellular carcinoma in 41.1%, contrasting with 38.9%, 32.7% and 22.0%, respectively, of female patients during 30 years. The Markov model could simulate the outcomes of 153 HCV carriers identified among blood donors after 5 years. The Markov simulation would help in assessing the long-term outcome of HCV infection and making decisions in the management of HCV carriers toward prevention of hepatocellular carcinoma.

Adult↗
PubMed2003

Effect of high concentration of glucose on dopamine release from pheochromocytoma-12 cells.

To investigate the mechanism of the action of high concentration of glucose on transmitter release from neuronal cells, we examined the effect of high concentration of glucose on dopamine release from pheochromocytoma-12 (PC12) cells. When the cells were incubated with 9.0 or 13.5 mg/mL glucose (2- or 3-fold of the optimum glucose concentration for PC12 cells), dopamine release was increased in a dose-related manner. Glucose-induced increase in dopamine release was blunted by nicardipine, a Ca2+ channel blocker. Following addition of 13.5 mg/mL glucose, intracellular Ca2+ concentration was increased, which was eliminated by nicardipine. Administration of 9.0 or 13.5 mg/mL glucose induced membrane depolarization in a dose-related manner. Glucose-induced dopamine release was inhibited by pinacidil or diazoxide, adenosine triphosphate (ATP)-sensitive K+ channel (KATP channel) openers. These results suggest that a high concentration of glucose induced ATP production, which blocked the KATP channel to induce membrane depolarization, and increased intracellular Ca2+ concentration and dopamine release. When the cells were cultured with 9.0 or 13.5 mg/mL glucose for 7 days, high potassium chloride (KCl)-induced dopamine release and 45Ca2+ uptake were increased. These results suggest that long-term incubation with a high concentration of glucose increased the capacity of Ca2+ uptake to enhance depolarization-induced dopamine release from PC12 cells. These data taken together suggest that a high concentration of glucose induced activation of the Ca2+ channel to stimulate dopamine release from PC12 cells.

Adenosine Triphosphate↗
PubMed2003

Effect of polymorphism of the endothelial nitric oxide synthase and apolipoprotein E genes on carotid atherosclerosis in hemodialysis patients.

BACKGROUND: Decreased synthesis of nitric oxide (NO) and dyslipidemia are implicated in the development of atherosclerosis. METHODS: We investigated the relationship between endothelial NO synthase (eNOS) gene polymorphism, apolipoprotein E (apoE) polymorphism, and carotid atherosclerosis in 163 hemodialysis patients with nondiabetic nephropathy. Intima media thickness of the carotid artery was measured by ultrasonography, and subjects were classified according to the presence or absence of carotid plaque. Multivariate odds ratios were calculated to assess the combined influence of several variables on the existence of carotid plaque, with clinical factors, the intron 4 polymorphism, T(-786)-->C polymorphism, and Glu298Asp polymorphism of eNOS and the apoE polymorphism tested as independent predictors. We also investigated the combined effect of these polymorphisms on risk for plaque. RESULTS: The odds ratio for carotid plaque positivity was increased to 3.72 by the a allele of the intron 4 polymorphism and increased to 3.36 by the C allele of the T(-786)-->C polymorphism, but was not increased in subjects with the T allele of the Glu298Asp polymorphism or those with the epsilon4 allele of the apoE polymorphism. However, the odds ratio for plaque positivity was significantly increased to 4.00 by possession of the a allele and/or epsilon4 allele and also increased to 4.04 by the C allele and/or epsilon4 allele. CONCLUSION: This cross-sectional study showed a synergistic effect between the intron 4 polymorphism or T(-786)-->C polymorphism of the eNOS gene and the apoE polymorphism with respect to risk for carotid atherosclerosis in nondiabetic hemodialysis patients.

Adult↗
PubMed2003

Lack of epidemiological evidence for a role of resolved hepatitis B virus infection in hepatocarcinogenesis in patients infected with hepatitis C virus in Japan.

OBJECTIVE: The role of resolved hepatitis B virus (HBV) infection in promoting hepatocellular carcinoma (HCC) in patients infected with hepatitis C virus (HCV) in Japan was evaluated by epidemiological surveys. METHODS: Antibody to hepatitis B core (anti-HBc) was determined in age-matched blood donors, and the frequency was compared with that in patients with HCV-associated HCC in Japan. RESULTS: Anti-HBc was detected significantly more frequently in the blood donors with than without antibody to HCV (anti-HCV; 76/135 or 56.3% vs. 65/255 or 25.5%, p < 0.001). In the patients with HCV-associated HCC, anti-HBc was detected in 109 of 202 (54.0%), which was comparable to the frequency in anti-HCV-positive blood donors (56.3%). Among the blood donors with anti-HCV, the prevalence of anti-HBc was no different between those with and without HCV RNA in serum (40/77 or 51.9% vs. 36/58 or 62.1%). CONCLUSIONS: The individuals of an age with high cancer frequency (>or=40 years) in Japan would have been exposed to HBV frequently (>50%), whether or not they have developed HCV-associated HCC. Despite repeated assertions in the literature, no epidemiological evidence was obtained for a role of past HBV infection in hepatocarcinogenesis in patients infected with HCV in Japan.

Aged↗
PubMed2002

Molecular cloning and expression of a second chondroitin N-acetylgalactosaminyltransferase involved in the initiation and elongation of chondroitin/dermatan sulfate.

We identified a novel human chondroitin N-acetylgalactosaminyltransferase, designated chondroitin GalNAcT-2 after a BLAST analysis of the GenBank(TM) data base using the sequence of a previously described human chondroitin N-acetylgalactosaminyltransferase (chondroitin GalNAcT-1) as a probe. The new cDNA sequence contained an open reading frame encoding a protein of 542 amino acids with a type II transmembrane protein topology. The amino acid sequence displayed 60% identity to that of human chondroitin GalNAcT-1. Like chondroitin GalNAcT-1, the expression of a soluble form of the protein in COS-1 cells produced an active enzyme, which not only transferred beta1,4-N-acetylgalactosamine (GalNAc) from UDP-[(3)H]GalNAc to a polymer chondroitin representing growing chondroitin chains (beta-GalNAc transferase II activity) but also to GlcUA beta 1-3Gal beta 1-O-C(2)H(4)NHCbz, a synthetic substrate for beta-GalNAc transferase I that transfers the first GalNAc to the core tetrasaccharide in the protein-linkage region of chondroitin sulfate. In contrast, the tetrasaccharide serine (GlcUA beta 1-3Gal beta 1-3Gal beta 1-4Xyl beta 1-O-Ser) derived from the linkage region, which is an inert acceptor substrate for chondroitin GalNAcT-1, served as an acceptor substrate. The coding region of this enzyme was divided into seven discrete exons, which is similar to the genomic organization of the chondroitin GalNAcT-1 gene, and was localized to chromosome 10q11.22. Northern blot analysis revealed that the chondroitin GalNAcT-2 gene exhibited a ubiquitous but differing expression in human tissues, and the expression pattern differed from that of chondroitin GalNAcT-1. Thus, we demonstrated redundancy in the chondroitin GalNAc transferases involved in the biosynthetic initiation and elongation of chondroitin sulfate, which is important for understanding the biosynthetic mechanisms leading to the selective chain assembly of chondroitin/dermatan sulfate on the linkage region tetrasaccharide common to various proteoglycans containing chondroitin/dermatan sulfate and heparin/heparan sulfate chains.

Amino Acid Sequence↗
PubMed2002

Possible involvement of tetrahydrobiopterin in the trophic effect of insulin-like growth factor-1 on rat pheochromocytoma-12 (PC12) cells.

Tetrahydrobiopterin (BH(4)) has a trophic effect on pheochromocytoma-12 (PC12) cells such as insulin-like growth factor-1 (IGF-1). We investigated involvement of BH(4) in the trophic effect of IGF-1 on PC12 cells. IGF-1 (10-300 ng/ml) increased cellular BH(4) content in a dose-related manner. Cellular BH(4) content increased after 6-36 h incubation with IGF-1. IGF-1-induced increase in the cellular BH(4) content was blunted by 0.3 mM 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor for BH(4) synthesis. IGF-1 protected PC12 cells from the cell death induced by depletion of serum and nerve growth factor, which was attenuated by DAHP. The effects of IGF-1 on the cellular BH(4) content and cell viability were eliminated by 0.2 microM wortmannin. These results suggest that BH(4) is involved in the trophic effect of IGF-1 on PC12 cells and that the effect of IGF-1 on BH(4) synthesis is mediated by phosphatidylinositol 3-kinase.

Androstadienes↗
PubMed2002

Effect of continuous subcutaneous administration of a low dose of G-CSF on stem cell mobilization in healthy donors: a feasibility study.

We investigated the effects of low-dose granulocyte colony-stimulating factor (G-CSF) on the mobilization of stem cells in 6 healthy subjects. When G-CSF was administered by continuous subcutaneous infusion at a rate of 72 microg/day for 5 days, the numbers of white blood cells and granulocytes rapidly increased to maximal levels. CD34+ cells were mobilized to the peripheral blood in 3 days, and the maximal level was reached 4 or 5 days after the start of treatment. We attempted to determine whether the levels of mobilized stem cells that we could obtain using this method would be sufficient for peripheral blood stem cell transplantation. Two of the 6 subjects complained of mild bone pain 4 or 5 days after the start of treatment, but the pain did not affect their daily activities. Only 1 abnormal result (for serum alkaline phosphatase) was found in the laboratory data. The present preliminary results have provided us with a framework for a prospective study comparing low-dose continuous infusion with conventional mobilization procedures.

Adult↗
PubMed2002

Involvement of nitric oxide in glucose toxicity on differentiated PC12 cells: prevention of glucose toxicity by tetrahydrobiopterin, a cofactor for nitric oxide synthase.

Effects of high concentrations of glucose on cell survival of differentiated PC12 cells were examined. Seven day-culture with D-glucose (9.0-27.0 mg/ml as 2-6-fold of the optimal level) induced cell death in a dose-related manner but 3-day culture with high concentrations of glucose had no effect on cell viability. L-glucose had no effect on viability of PC12 cells, suggesting that D-glucose toxicity was independent of its osmolarity effect. Seven-day culture with D-glucose (13.5 mg/ml as 3-fold of the optimal level) increased nitric oxide metabolites (NOx) in the culture medium. Glucose-induced increase in NOx was eliminated by 0.1 mM L-nitro-arginine methylester (L-NAME), a nitric oxide synthase (NOS) inhibitor. Intracellular Ca(2+) concentration was increased by D-glucose in a dose-related manner, suggesting that D-glucose activated NOS by increasing intracellular Ca(2+) concentration in PC12 cells. Glucose-induced cell death was blunted by 0.1 mM L-NAME, showing that nitric oxide (NO) was involved in the glucose toxicity to PC12 cells. Tetrahydrobiopterin (BH(4)), a cofactor for NOS, attenuated both glucose-induced cell death and NOx production at 1 microM but not at 10 microM. The effects of BH(4) on glucose-induced cell death and NOx production were not mimicked by reducing agents such as ascorbate and cysteine. These results taken together suggest that high concentrations of glucose induced cell death via NO production and that low concentration of BH(4) had a protective effect against glucose neurotoxicity in differentiated PC12 cells.

Animals↗
PubMed2002

High incidence of extrahepatic manifestations in an HCV hyperendemic area.

We previously investigated the incidence of extrahepatic manifestations including oral precancerous disease among the inhabitants in a hepatitis C virus (HCV) hyperendemic area in Fukuoka in Japan. The present study design was based on a prospective cohort at the other HCV hyperendemic area. One oral surgeon examined the oral lesions of 59 adult inhabitants (21 men, 38 women; mean age of 70.7 years), of a hyperendemic area of HCV infection. Furthermore, all subjects were interviewed regarding the natural history of extrahepatic manifestations. All sera were examined for antibodies to HCV (anti-HCV), serum HCV RNA, HCV genotype, antinuclear antibody (ANA), rheumatoid factor (RF) activity, and anti-SS-A and-B antibodies. Anti-HCV or HCV RNA was detected in sera from 59 (100%) or 57 (96.7%) of all subjects. Oral lichen planus (OLP), leukoplakia with leukoedema, or only leukoedema was observed in 8 (8.5%), 1 (1.7%), or 2 (3.4%) subjects, respectively. The incidence of all subjects with one or more HCV-related extrahepatic manifestation was 66.1% (39/59). The subjects with dry mouth were 25.4% (15/59). There was no relation among these autoantibodies, symptoms of dry mouth, or prevalence of HCV-associated extrahepatic manifestations. These findings demonstrate that the inhabitants with HCV infection showed various extrahepatic manifestations, and was not always limited to specific HCV areas.

Journal Article↗
PubMed2002

Control of DNA replication and chromosome ploidy by geminin and cyclin A.

Alteration of the control of DNA replication and mitosis is considered to be a major cause of genome instability. To investigate the mechanism that controls DNA replication and genome stability, we used the RNA silencing-interference technique (RNAi) to eliminate the Drosophila geminin homologue from Schneider D2 (SD2) cells. Silencing of geminin by RNAi in SD2 cells leads to the cessation of mitosis and asynchronous overreplication of the genome, with cells containing single giant nuclei and partial ploidy between 4N and 8N DNA content. The effect of geminin deficiency is completely suppressed by cosilencing of Double parked (Dup), the Drosophila homologue of Cdt1, a replication factor to which geminin binds. The geminin deficiency-induced phenotype is also partially suppressed by coablation of Chk1/Grapes, indicating the involvement of Chk1/Grapes in the checkpoint control in response to overreplication. We found that the silencing of cyclin A, but not of cyclin B, also promotes the formation of a giant nucleus and overreplication. However, in contrast to the effect of geminin knockout, cyclin A deficiency leads to the complete duplication of the genome from 4N to 8N. We observed that the silencing of geminin causes rapid downregulation of Cdt1/Dup, which may contribute to the observed partial overreplication in geminin-deficient cells. Analysis of cyclin A and geminin double knockout suggests that the effect of cyclin A deficiency is dominant over that of geminin deficiency for cell cycle arrest and overreplication. Together, our studies indicate that both cyclin A and geminin are required for the suppression of overreplication and for genome stability in Drosophila cells.

Animals↗