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Atsushi Tanaka

Publications and source records attributed to Atsushi Tanaka.

At least 19 recordsLinked to original sources
PubMed2026

Current Management of Primary Sclerosing Cholangitis (PSC) ~A Proposal for Early-stage PSC~.

Primary sclerosing cholangitis (PSC) is a chronic, progressive cholangiopathy characterized by inflammation and fibrosis of intrahepatic and/or extrahepatic bile ducts. Its pathogenesis remains incompletely understood, and liver transplantation is currently the only curative treatment available. The diagnosis remains challenging, and no disease-specific biomarkers have been established. Recently, anti-integrin αvβ6 antibodies have emerged as promising serological biomarkers with high specificity for PSC. Advances in imaging modalities, including magnetic resonance cholangiopancreatography and peroral cholangioscopy, have improved diagnostic accuracy for PSC. Although various therapeutic approaches have been investigated, no treatment has been shown to improve the long-term outcomes. Microbiota-targeted therapies represent a promising emerging strategy. The clinical course of PSC, particularly in its early stages, is poorly defined. We propose a definition of early stage PSC consisting of two subtypes: small-duct PSC without liver fibrosis and large-duct PSC without cholestatic enzyme elevation or biliary strictures. Early intervention at this stage may improve the prognosis, thus highlighting the need for further validation.

Primary sclerosing cholangitis↗
PubMed2026

Impact of estimated total blood volume on NT-proBNP response to angiotensin receptor-neprilysin inhibition in acute heart failure: Insights from the PREMIER study.

BACKGROUND: Sacubitril/valsartan (Sac/Val) reduces N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels in acute heart failure (AHF), particularly in patients with reduced ejection fraction. However, whether estimated total blood volume (TBV), calculated using anthropometric equations, is associated with heterogeneity in biomarker response remains uncertain. METHODS: This post hoc exploratory sub-analysis of the PREMIER randomized trial evaluated whether baseline estimated TBV was associated with heterogeneity in NT-proBNP reduction after Sac/Val compared with angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (ACEI/ARB) therapy. Estimated TBV was calculated using validated anthropometric equations and dichotomized at the median (4.05 L). Patients were further stratified by left ventricular ejection fraction (LVEF <40% vs &#x2265;40%). The primary endpoint was the proportional change in NT-proBNP from baseline to Week 8. RESULTS: Among 376 patients, 372 with baseline estimated TBV data were analyzed. In the high TBV group, Sac/Val was associated with greater NT-proBNP reduction than ACEI/ARB (-56% vs -32%; ratio of change, 0.67; 95% confidence interval, 0.53-0.84; P = .001), whereas no significant difference was observed in the low TBV group (P for heterogeneity = 0.063). In patients with LVEF <40%, Sac/Val was associated with greater NT-proBNP reduction in both TBV groups. In patients with LVEF &#x2265;40%, Sac/Val was associated with greater NT-proBNP reduction in the high TBV group, whereas the point estimate in the low TBV group numerically favored ACEI/ARB. CONCLUSIONS: In this exploratory post hoc analysis, higher estimated TBV was associated with greater NT-proBNP reduction after Sac/Val, particularly among patients with LVEF &#x2265;40%. These findings are hypothesis-generating and require external validation. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05164653; Japan Registry of Clinical Trials, jRCTs021210046.

Humans↗
PubMed2006

Effect of cyclosporin A on the biliary excretion of cholephilic compounds in rats.

Cyclosporin A (CsA) is known to cause cholestasis. CsA is reported to competitively inhibit the transport of the substrates of the bile salt export pump (Bsep), multidrug resistance protein 2 (Mrp2) and P-glycoprotein (P-gp) in the canalicular membrane vesicles. However, the inhibitory effect of CsA on various substrates of the canalicular ATP-dependent transporters in vivo is unknown. Therefore, in the present study, the acute effect of CsA on the biliary excretion of the substrates of Bsep, Mrp2 and P-gp was examined under the same condition. Ten minutes after the intravenous administration of CsA (25mg/kg), the biliary excretion of various bile acids and organic anions and cations was studied. CsA decreased the biliary excretion of tracer amounts of taurocholate, leukotriene C(4), estradiol-17beta-glucuronide, pravastatin, vinblastine and erythromycin. In contrast, the biliary excretion of high doses of taurocholate and sulfobromophthalein was only slightly or not inhibited by CsA. In conclusion, CsA may competitively inhibit biliary excretion of substrates of Bsep, Mrp2 and P-gp also in vivo, and CsA is considered to inhibit bile acid-dependent bile flow by the competitive inhibition of the canalicular transport of bile acids by Bsep.

Journal Article↗
PubMed2006

Isolation of the feline alpha1,3-galactosyltransferase gene, expression in transfected human cells and its phylogenetic analysis.

The enzyme alpha 1,3-galactosyltransferase (alpha1,3-GT), which catalyzes synthesis of terminal alpha-galactosyl epitopes (Gal alpha1,3Gal beta1-4GlcNAc-R), is produced in non-primate mammals, prosimians and new-world monkeys, but not in old-world monkeys, apes and humans. We cloned and sequenced a cDNA that contains the coding sequence of the feline alpha1,3-GT gene. Flow cytometric analysis demonstrated that the alpha-galactosyl epitope was expressed on the surface of a human cell line transduced with an expression vector containing this cDNA, and this alpha-galactosyl epitope expression subsided by alpha-galactosidase treatment. The open reading frame of the feline alpha1,3-GT cDNA is 1,113 base pairs in length and encodes 371 amino acids. The nucleotide sequence and its deduced amino acid sequence of the feline alpha1,3-GT gene are 88-90% and 85-87%, respectively, similar to the reported sequences of the bovine, porcine, marmoset and cebus monkey alpha1,3-GT genes, while they are 88% and 82-83%, respectively, similar to those of the orangutan and human alpha1,3-GT pseudogenes, and 81% and 77%, respectively, similar to the murine alpha1,3-GT gene. Thus, the alpha1,3-GT genes and pseudogenes of mammals are highly similar. Ratios of non-synonymous nucleotide changes among the primate pseudogenes as well as the primate genes are still higher than the ratios of non-primates, suggesting that the primate alpha1,3-GT genes tend to be divergent.

Amino Acid Sequence↗
PubMed2005

The very 5' end and the constant region of Ig genes are spared from somatic mutation because AID does not access these regions.

Somatic hypermutation (SHM) is restricted to VDJ regions and their adjacent flanks in immunoglobulin (Ig) genes, whereas constant regions are spared. Mutations occur after about 100 nucleotides downstream of the promoter and extend to 1-2 kb. We have asked why the very 5' and most of the 3' region of Ig genes are unmutated. Does the activation-induced cytosine deaminase (AID) that initiates SHM not gain access to these regions, or does AID gain access, but the resulting uracils are repaired error-free because error-prone repair does not gain access? The distribution of mutations was compared between uracil DNA glycosylase (Ung)-deficient and wild-type mice in endogenous Ig genes and in an Ig transgene. If AID gains access to the 5' and 3' regions that are unmutated in wild-type mice, one would expect an "AID footprint," namely transition mutations from C and G in Ung-deficient mice in the regions normally devoid of SHM. We find that the distribution of total mutations and transitions from C and G is indistinguishable in wild-type and Ung-deficient mice. Thus, AID does not gain access to the 5' and constant regions of Ig genes. The implications for the role of transcription and Ung in SHM are discussed.

5' Untranslated Regions↗
PubMed2005

Comparison of levels of serum matrix metalloproteinase-9 in patients with acute myocardial infarction versus unstable angina pectoris versus stable angina pectoris.

Matrix metalloproteinases (MMPs) are important for resorption of extracellular matrixes and may degrade the fibrous cap of an atherosclerotic plaque, thus contributing to coronary plaque rupture. Histologic studies have shown MMP expression in lesions of acute coronary syndrome. In this study, we evaluated the relation between plaque morphology as obtained by intravascular ultrasound before percutaneous coronary intervention and serum MMP levels in patients who had coronary artery disease. We enrolled consecutive 47 patients who had acute myocardial infarction (AMI), 23 who had unstable angina pectoris (UAP), and 19 who had stable effort angina pectoris and underwent intravascular ultrasound before percutaneous coronary intervention followed by successful primary percutaneous coronary intervention. Peripheral blood was obtained from all patients before angiography and serum levels of MMP-1,-2, and -9 were analyzed. Serum levels of MMP-9 in the AMI and UAP groups were significantly higher than that in the stable effort angina pectoris group (p = 0.007 and 0.04, respectively). From the intravascular ultrasound findings before percutaneous coronary intervention, plaque rupture was detected in 26 patients (55%) in the AMI group and in 11 patients (48%) in the UAP group. In these 2 groups, patients with plaque rupture had significantly higher levels of MMP-9 than patients who did not have plaque rupture (p = 0.03 and 0.01, respectively). Multiple logistic regression analysis showed that MMP-9 was the only independent predictor of plaque rupture (p = 0.004). In conclusion, high levels of MMP-9 in patients who have AMI and UAP are related to the presence of plaque rupture in the culprit lesion.

Aged↗
PubMed2005

A case of cutaneous polyarteritis nodosa manifested by spiking high fever, arthralgia and macular eruption like adult-onset Still's disease.

A 24-year-old Japanese woman was admitted for investigation of recurrent spiking high fever associated with a macular eruption of the upper extremities associated with fever and polyarthralgia. These symptoms were self-limiting but recurrent and seemed to be consistent with a diagnosis of adult-onset Still's disease (AOSD). However, livedo reticularis was detected on the lower extremities, suggesting the presence of vasculitic disease rather than AOSD. Investigation did not reveal any evidence of visceral involvement. Skin biopsy of the affected lower extremity demonstrated a necrotizing vasculitis of small muscular artery and confirmed a diagnosis of cutaneous polyarteritis nodosa (PAN) rather than AOSD. Treatment with 30 mg of prednisolone daily improved the skin lesions and the recurrent spiking high fever and the arthralgia were resolved. PAN and AOSD are clinically similar, and discrimination may be sometimes difficult. The presence of livedo reticularis and the finding of a characteristic skin biopsy appearance may be diagnostically useful to distinguish PAN from AOSD. Indeed, the clinical features of cutaneous PAN may be more similar to AOSD than systemic PAN, and a skin biopsy may be necessary to distinguish cutaneous PAN from AOSD in some cases.

Adult↗
PubMed2005

The synthetic peptide derived from the NH2-terminal extracellular region of an orphan G protein-coupled receptor, GPR1, preferentially inhibits infection of X4 HIV-1.

Several G protein-coupled receptors (GPCRs) serve as co-receptors for entry of human immunodeficiency virus type 1 (HIV-1) into target cells. Here we report that a synthetic peptide derived from the NH2-terminal extracellular region of an orphan GPCR, GPR1 (GPR1ntP-(1-27); MEDLEETLFEEFENYSYDLDYYSLESC), inhibited infection of not only an HIV-1 variant that uses GPR1 as a co-receptor, but also X4, R5, and R5X4 viruses. Among these HIV-1 strains tested, viruses that can utilize CXCR4 as their co-receptors were preferentially inhibited. Inhibition of early steps in X4 virus replication was also detected in the primary human peripheral blood lymphocytes. GPR1ntP-(1-27) directly interacted with recombinant X4 envelope glycoprotein (rgp120). This interaction was neither inhibited nor enhanced by the soluble CD4 (sCD4) but inhibited by the anti-third variable (V3) loop-specific monoclonal antibody and heparin known to bind to the V3 loop. Although the conformational changes in gp120, including the V3 loop, have been reported to be required for its interaction with a co-receptor after binding of gp120 to CD4, it has also been reported that the V3 loop is already exposed on the surface of virions before interaction with CD4. We found that GPR1ntP-(1-27) blocked binding of virus to the cells, and this peptide equally bound to rgp120 in the presence or absence of sCD4. Because we detected the binding of GPR1ntP-(1-27) to the highly purified virions even in the absence of sCD4, GPR1ntP-(1-27) probably recognized the V3 loop exposed on the virions, and this interaction was responsible for the anti-HIV-1 activity of GPR1ntP-(1-27).

Amino Acid Sequence↗
PubMed2005

Roles of Arabidopsis AtREV1 and AtREV7 in translesion synthesis.

Plants have mechanisms for repairing and tolerating detrimental effects by various DNA damaging agents. A tolerance pathway that has been predicted to be present in higher plants is translesion synthesis (TLS), which is catalyzed by polymerases. In Arabidopsis (Arabidopsis thaliana), however, the only gene known to be involved in TLS is the Arabidopsis homolog of REV3, AtREV3, which is a putative catalytic subunit of Arabidopsis DNA polymerase zeta. A disrupted mutant of AtREV3, rev3, was previously found to be highly sensitive to ultraviolet-B (UV-B) and various DNA damaging agents. REV1 and REV7 are thought to be components of translesion synthesis in plants. In this study, we identified the Arabidopsis homologs of REV1 and REV7 (AtREV1 and AtREV7). Several mutants carrying disrupted AtREV1 and AtREV7 genes were isolated from Arabidopsis T-DNA-inserted lines. An AtREV1-disrupted mutant, rev1, was found to be moderately sensitive to UV-B and DNA cross-linkers. A rev1rev3 double mutant, like rev3, showed high sensitivity to UV-B, gamma-rays, and DNA cross-linkers. An AtREV7-disrupted mutant, rev7, was possibly sensitive to cis-diamminedichloroplatinum(II), a kind of DNA cross-linker, but it was not sensitive to acute UV-B and gamma-ray irradiation. On the other hand, the aerial growth of rev7, like the aerial growth of rev1 and rev3, was inhibited by long-term UV-B. These results suggest that a TLS mechanism exists in a higher plant and show that AtREV1 and AtREV7 have important roles in tolerating exposure to DNA-damaging agents.

Amino Acid Sequence↗
PubMed2005

Multiple plaque rupture and C-reactive protein in acute myocardial infarction.

OBJECTIVES: This study sought to investigate the relationship between multiple plaque ruptures, C-reactive protein (CRP), and clinical prognosis in acute myocardial infarction (AMI). BACKGROUND: Several studies have demonstrated that ruptured or vulnerable plaques exist not only at the culprit lesion but also in the whole coronary artery in some acute coronary syndrome (ACS) patients. Recent studies have reported that a ruptured plaque at the culprit lesion is associated with elevated CRP, which indicates a poor prognosis in patients with ACS. METHODS: We performed intravascular ultrasound in 45 infarct-related arteries and another 84 major coronary arteries in 45 first AMI patients. RESULTS: Plaque rupture was observed in 21 patients (47%) at the culprit site. Intravascular ultrasound revealed 17 additional plaque ruptures at remote sites in 11 patients (24%). Patients with multiple risk factors were more frequently found in our multiple-plaque rupture patients compared with single-plaque rupture or nonrupture patients (82% vs. 40% vs. 29%, p = 0.01). High-sensitive CRP levels had a positive correlation with the number of plaque ruptures (p < 0.01). All culprit lesions were successfully treated by percutaneous coronary intervention. Patients with multiple plaque rupture showed significantly poor prognosis compared with others (p = 0.01). CONCLUSIONS: Multiple plaque rupture is associated with systemic inflammation, and patients with multiple plaque rupture can be expected to show a poor prognosis. Our results suggest that AMI treatment should focus not only on stabilization of the culprit site but also a systemic approach to systemic stabilization of the arteries.

Aged↗
PubMed2005

Ectopic endoreduplication caused by sterol alteration results in serrated petals in Arabidopsis.

The Arabidopsis frill1 (frl1) mutant, that has serrated petals and sepals but no other large changes in plant morphology, was studied. The frl1 had a mutation in STEROL METHYLTRANSFERASE 2 and an altered sterol composition. It was found that the frl1 mutation causes ectopic endoreduplication in petal tips that do not normally endoreduplicate. The rosette leaves of frl1 also showed an enhanced level of endoreduplication, but their morphology was hardly affected. These facts suggest that the suppression of endoreduplication is important for petal morphogenesis and the normal sterol composition is required for this suppression.

Arabidopsis↗
PubMed2005

Analysis of mutations induced by carbon ions in Arabidopsis thaliana.

To investigate the nature of mutations induced by accelerated ions in higher plants, the effects of carbon-ion-irradiation were compared with those of electron-irradiation in Arabidopsis thaliana. Point-like mutations and rearrangements were induced at a similar frequency after carbon-ion-irradiation, whereas point-like mutations were more frequently induced after electron-irradiation. Sequence analysis revealed that carbon-ion-induced point-like mutations were mostly short deletions. In the case of rearrangements, deletions, inversions, insertions, and translocations were found. The estimated frequency of deletion induction was comparable to that of fast neutrons. Analysis of chromosome breakpoints revealed that carbon ions frequently deleted small regions around the breakpoints, whereas electron-irradiation often duplicated these regions. Moreover, for both types of radiation, broken ends with microhomologies were frequently rejoined. Results of the breakpoint and broken end analyses suggest that non-homologous end-joining (NHEJ) leads to the rejoining of double strand breaks (dsbs) after cells are exposed to both types of radiation, but the type of NHEJ that occurs as a result of damage is different. The results indicated that carbon-ion-induced mutations are most likely nulls and that the induced rearrangements may arise through a unique mechanism. These findings indicate that accelerated ions are a useful mutagen for both forward and reverse genetics for plants.

Arabidopsis↗
PubMed2005

Efficacy of ribavirin monotherapy following combination therapy with interferon alfa-2b and ribavirin for patients with chronic hepatitis C.

Reappearance of HCV-RNA followed by exacerbation of biochemical parameters after combination therapy consisting of interferon and ribavirin is an obstacle to achieve sustained response and improve long-term prognosis. We hypothesed that ribavirin monotherapy after 6 months of combination therapy may improve sustained viral and biochemical responses, and conducted a prospective, randomized and controlled study. Thirty-eight patients with chronic hepatitis C treated with combination therapy for 6 months and had no detectable serum HCV-RNA were enrolled, and allocated into two arms. Group I (n=19) was continuously administered oral ribavirin for additional 6 months, and group II (n=19) was followed up without any further treatment. At the end of trial, HCV-RNA negativity was 11/19 (58%) in group I, and 6/19 (32%) in group II (p=0.191). Multivariant analysis demonstrated that ribavirin monotherapy was not a predictor for the eradication of HCV-RNA. In cases without sustained viral responses, serum ALT levels at baseline and the end of 48 weeks' trial were 54.6 and 44.4 in group I (p=0.237), and significant reduction with ribavirin monotherapy was not observed. In conclusion, ribavirin monotherapy following combination therapy fails to improve sustained viral response as well as biochemical response.

Journal Article↗
PubMed2005

klavier (klv), a novel hypernodulation mutant of Lotus japonicus affected in vascular tissue organization and floral induction.

A novel hypernodulation mutant line was isolated from Lotus japonicus Miyakojima MG-20 by irradiation with a helium ion beam. This mutant, named klavier (klv), had roots that were densely covered with small nodules. The nodulation zone of klv was significantly wider than that of the wild type. Grafting experiments showed that klv is impaired in the long-distance shoot-to-root autoregulatory mechanism. Thus the shoot genotype was found to be responsible for the negative regulation of nodule development by KLV. Nodulation of klv showed a higher tolerance to nitrogen (KNO3) than the wild type, which is a common feature of hypernodulating mutants. In addition to an increased number of nodules, the klv mutant showed convex leaf veins on the adaxial leaf surface, markedly delayed flowering and dwarf phenotypes. Microscopic examination of the leaf veins revealed that they were discontinuous. Other phenotypes such as fasciated stems, increased number of flowers and bifurcated pistils were also frequently observed in the klv mutant. Among these phenotypes, hypernodulation, aberrant leaf vein formation and significantly delayed flowering were all linked in a monogenic and recessive manner, indicating that these phenotypes are caused by either a single mutation, or tightly linked mutations. KLV was mapped within 0.29 cM on the long arm of chromosome 1.

Flowers↗
PubMed2005

Prevalence and clinical course of the juveniles with Brugada-type ECG in Japanese population.

BACKGROUND: Although many studies on Brugada syndrome have been done, with many reports of genetic findings and clinical features, little evidence exists to support the role of this syndrome in sudden cardiac death in a juvenile population. We sought to determine the prevalence and clinical course in children exhibiting Brugada-type ECG in a community-based population. METHODS: Our study population comprised 21,944 subjects (11,282 boys and 10,662 girls) who underwent ECG during their first-year elementary school health examinations between 1992 and 2001 in Izumi City, Osaka. Brugada-type ECG was defined as demonstrating ST-segment elevation (coved or saddle-back type, J wave amplitude > or =0.2 mV) in the right precordial leads. We also divided Brugada-type ECGs into three types according to a consensus report. Type 1: coved ST-segment elevation displaying high J wave amplitude followed by a negative T wave; Type 2: high take-off and gradually descending ST-segment elevation (remaining > or =1 mm) followed by a positive or biphasic T wave; and Type 3: ST-segment elevation of <1 mm of both types. RESULTS: Four subjects showed Brugada-type ECG (0.02%) (2 boys and 2 girls). Only one subject, a girl, met Type 1 criteria (0.005%). No history of structural heart disease was documented in these four subjects. During 6.8 +/- 1.0 years of follow-up, no episode of unexpected sudden death, syncopal attack, and fatal arrhythmia occurred. CONCLUSIONS: The prevalence of Brugada-type ECG in a juvenile population was extremely low. To investigate when the typical Brugada-type ECG might be manifested, it could be necessary to check ECGs after adolescence.

Bundle-Branch Block↗
PubMed2005

Formation of vesicular stomatitis virus pseudotypes bearing surface proteins of hepatitis B virus.

It has been difficult to propagate and titrate hepatitis B virus (HBV) in tissue culture. We examined whether vesicular stomatitis virus (VSV) pseudotypes bearing HBV surface (HBs) proteins infectious for human cell lines could be prepared. For this, expression plasmids for three surface proteins, L, M, and S, of HBV were made. 293T cells were then transfected with these plasmids either individually or in different combinations. 293T cells expressing HBs proteins were infected with VSVdeltaG*-G, a recombinant VSV expressing green fluorescent protein (GFP), to make VSV pseudotypes. Culture supernatants together with cells were harvested and sonicated for a short time. The infectivities of freshly harvested supernatants were determined by quantifying the number of cells expressing GFP after neutralization with anti-VSV serum and mouse monoclonal antibodies (MAbs) against HBs protein. Among 14 cell lines tested for susceptibility to HBV pseudotype samples, HepG2, JHH-7, and 293T cells were judged to be the most susceptible. Namely, the infectious units (IU) of the culture supernatant samples neutralized with anti-VSV in the absence and presence of anti-HBs S MAbs and titrated on HepG2 cells ranged from 1,000 to 4,000 IU/ml and 200 to 400 IU/ml, respectively, suggesting the presence of VSVdeltaG*(HBV) pseudotypes. This infectivity was inhibited by treatment with lactoferrin or dextran sulfate. Pretreatment of the cells with trypsin or tunicamycin inhibited plating of the pseudotype samples. The HBV pseudotypes can be used to analyze early steps of HBV infection, including the entry mechanism of HBV.

Antibodies, Monoclonal↗
PubMed2005

Genomic relationships among Nicotiana species with different ploidy levels revealed by 5S rDNA spacer sequences and FISH/GISH.

We used the intergenic spacer sequences of the 5S ribosomal RNA genes (5S rDNA) to obtain insights into the genomic origin of putative amphidiploid/tetraploid species with 2n = 48 and their descendants in Nicotiana. Amplification of the spacer sequences and subsequent multiple alignment using the consensus sequences from each species, showed that two Australian species shared common large deletions, suggesting that the origin of the 5S rDNA is closely related in these species. Comparison of the spacer sequences with those from diploid (2n = 24) Nicotiana species made it possible to detect some groups consisting of the sequences from the 2n = 24 and 2n = 48 level species. Chromosomal localizations of the 5S rDNA arrays were similar in most groups. The relationships suggested by the 5S rDNA were also assessed at the genome level by using genomic in situ hybridization. We showed that the grouping based on the 5S rDNA spacer sequence reflects high genomic homology between 2n = 24 and 2n = 48 level species. As a result, the putative polyploid species such as N. debneyi, N. quadrivalvis, and N. africana were suggested to involve the close relatives of the diploid species such as N. glauca, N. obtusifolia and N. sylvestris, and N. langsdorffii, respectively, in their speciation. Our results are generally in agreement with the relationships previously suggested by morphological and cytogenetic observations, and some novel relationships were also revealed.

Base Sequence↗