Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Kazuyoshi Nagayama is active.

Publication


Featured researches published by Kazuyoshi Nagayama.


Journal of Gastroenterology and Hepatology | 2001

Radiation therapy in combination with transcatheter arterial chemoembolization for hepatocellular carcinoma with extensive portal vein involvement

Junichi Tazawa; Manabu Maeda; Yoshinori Sakai; Michio Yamane; Hideo Ohbayashi; Sei Kakinuma; Yuka Miyasaka; Kazuyoshi Nagayama; Nobuyuki Enomoto; Chifumi Sato

The aim of this study was to examine the effectiveness and toxicity of radiation therapy in combination with transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) with extensive portal vein tumor thrombus (PVTT).


British Journal of Cancer | 2001

Analysis of differentially expressed genes in human hepatocellular carcinoma using suppression subtractive hybridization.

Yuka Miyasaka; Nobuyuki Enomoto; Kazuyoshi Nagayama; Namiki Izumi; Fumiaki Marumo; Mamoru Watanabe; Chifumi Sato

The genetic basis of hepatocellular carcinoma (HCC) has not yet been fully understood. Although various methods have been developed to detect differentially expressed genes in malignant diseases, efficient analysis from clinical specimens is generally difficult to perform due to the requirement of a large amount of samples. In the present study, we analysed differentially expressed genes with a small amount of human HCC samples using suppression subtractive hybridization (SSH). Total RNA were obtained from the hepatitis C virus-associated HCC and adjacent non-HCC liver tissues. cDNA was synthesized using modified RT-PCR, and then tester cDNA was ligated with 2 different kinds of adaptors and hybridized with an excess amount of driver cDNA. Tester specific cDNA was obtained by suppression PCR and the final PCR product was subcloned and sequenced. We identified 7 known genes (focal adhesion kinase, deleted in colon cancer, guanine binding inhibitory protein α, glutamine synthetase, ornithine aminotransferase, M130, and pepsinogen C) and 2 previously unknown genes as being overexpressed in HCC, and 1 gene (decorin) as suppressed in HCC. Quantitative analysis of gene expression using quantitative RT-PCR demonstrated the differential expression of these genes in the original and other HCC samples. These findings demonstrated that it is possible to identify the previously unknown, differential gene expression from a small amount of clinical samples. Information about such alterations in gene expression could be useful for elucidating the genetic events in HCC pathogenesis, developing the new diagnosic markers, or determining novel therapeutic targets.


The Journal of Infectious Diseases | 2001

Number and Position of Mutations in the Interferon (IFN) Sensitivity–Determining Region of the Gene for Nonstructural Protein 5A Correlate with IFN Efficacy in Hepatitis C Virus Genotype 1b Infection

Hideki Watanabe; Nobuyuki Enomoto; Kazuyoshi Nagayama; Namiki Izumi; Fumiaki Marumo; Chifumi Sato; Mamoru Watanabe

To explore the relationship between responses to interferon (IFN) and the mutation patterns in the IFN sensitivity-determining region (ISDR; amino acid positions 2209-2248) in the NS5A gene of hepatitis C virus genotype 1b, a cohort of 334 patients was analyzed. The number of mutations in the ISDR was higher in patients with sustained response (SR) than in patients with transient or no response (P<.001). Patients with viruses mutated at positions 2209 (P=.02), 2216 (P=.01), or 2227 (P=.02) more frequently experienced SR than did those without these mutations. Mutation occurred most frequently at position 2218, where the presence of cysteine was significantly associated with SR. Thus, the mutation pattern in the ISDR affects the virologic response to IFN and reflects different influences on the function of the NS5A protein. ISDR sequence analysis would allow the prediction of clinical IFN efficacy in individual patients.


The American Journal of Gastroenterology | 1999

Efficacy of endoscopic clipping for bleeding gastroduodenal ulcer: comparison with topical ethanol injection.

Kazuyoshi Nagayama; Junichi Tazawa; Yoshinori Sakai; Yuka Miyasaka; Shin-Han Yu; Ikuo Sakuma; Shinya Maekawa; Hideo Obayashi; Fumaiaki Marumo; Chifumi Sato

Objective:Although endoscopic clipping is used widely for the treatment of bleeding gastroduodenal ulcers, clinical trials on its efficacy are scarce. The aim of this study is to assess the efficacy and safety of endoscopic clipping for hemostasis from bleeding gastroduodenal ulcers.Methods:The present study was designed as a retrospective study using historical controls. One hundred consecutive patients with bleeding gastroduodenal ulcers were treated by endoscopic clipping. The preceding 91 consecutive patients treated by endoscopic pure ethanol injection were regarded as controls. Forty-nine of the clipping group and 41 of the ethanol group had lesions at sites difficult to perform endoscopic manipulation. Hemostatic rates, rebleeding rates, amounts of blood transfusion, and durations of hospital stay were analyzed.Results:The hemostatic rate was 96% in both clipping and ethanol groups, whereas the rebleeding rate was lower (15%vs 29%, p= 0.023) in the former than the latter. In technically difficult cases, the hemostatic rate was comparable (96 vs 90%).Conclusion:In patients with bleeding gastroduodenal ulcers, endoscopic clipping may be a choice of therapy because of a low rebleeding rate compared with pure ethanol injection.


The Journal of Infectious Diseases | 2004

Quantitation of the Level of Hepatitis Delta Virus RNA in Serum, by Real-Time Polymerase Chain Reaction—and Its Possible Correlation with the Clinical Stage of Liver Disease

Tsuyoshi Yamashiro; Kazuyoshi Nagayama; Nobuyuki Enomoto; Hideki Watanabe; Tsuyoshi Miyagi; Hiroki Nakasone; Hiroshi Sakugawa; Mamoru Watanabe

Some hepatitis B virus (HBV) carriers with chronic hepatitis delta virus (HDV) superinfection show progressive chronic hepatitis, whereas others show no apparent signs of liver disease. In the present study, we established a sensitive method for the quantitation of the level of HDV RNA in serum on the basis of real-time reverse-transcription polymerase chain reaction (RT-PCR), to clarify the role that the level of HDV RNA in serum plays in the diverse natural course of clinical manifestation. In 48 subjects who were positive for hepatitis B surface antigen and for anti-hepatitis delta antibody, the levels of HDV RNA in serum were quantitated by RT-PCR. The levels of HBV DNA in serum were determined by a transcription-mediated amplification assay. The levels of HDV RNA in serum of subjects with chronic hepatitis and of subjects with liver cirrhosis were significantly higher than those in asymptomatic carrier subjects. The levels of HBV DNA in serum did not differ significantly among these 3 groups. In conclusion, HDV RNA quantification by real-time RT-PCR is possibly a useful tool for understanding the pathophysiology of HDV infection.


Inflammatory Bowel Diseases | 2007

Extracorporeal elimination of TNF‐α‐producing CD14dullCD16+ monocytes in leukocytapheresis therapy for ulcerative colitis

Takanori Kanai; Shin Makita; Takahiro Kawamura; Yasuhiro Nemoto; Daisuke Kubota; Kazuyoshi Nagayama; Teruji Totsuka; Mamoru Watanabe

Background In recent years leukocytapheresis using a leukocyte removal filter (known as lymphocytapheresis, LCAP) has been applied to the treatment of various autoimmune diseases including ulcerative colitis (UC). In the present study we aimed to clarify how LCAP therapy modifies inflammatory responses by modulating circulating TNF‐&agr;‐producing monocytes. Methods Mononuclear cells were obtained from blood before and after the first treatment, and the expression profiles of various immune cells (naive versus. memory, regulatory CD4+CD25bright versus non‐regulatory CD4+CD25− T cells, and CD14+CD16− versus CD14dullCD16+ monocytes) were assessed. To evaluate immunological differences between CD14+CD16− and CD14dullCD16+ monocytes, the expression of TNF‐&agr;, IL‐6, IL‐12, IL‐10, IL‐18, surface toll‐like receptor 2 (TLR2), TLR4, and other activation markers including HLA‐DR, CD80 and CD86, as well as cytokine profiles, were analyzed. Results LCAP treatment selectively removed CD14dullCD16+ monocytes, which preferentially produce TNF‐&agr; and IL‐12 and express HLA‐DR, CD80, CD86, and TLR2, compared with the major fraction of CD14+CD16− monocytes, which conversely produce a higher amount of IL‐10. In addition, the CD4+CD45RO+CD62L−/CD4+CD45RO+CD62L+ ratio was significantly lower after LCAP therapy. However, the CD4+CD25bright/total CD4+ ratio did not change. Conclusions The present findings revealed the real target of proinflammatory CD14dullCD16+ monocytes removed during LCAP treatment of UC and that LCAP might be used as an extracorporeal anti‐TNF‐&agr; therapy, expanding the clinical applications of this procedure to include the treatment of Crohns disease. (Inflamm Bowel Dis 2006)


The American Journal of Gastroenterology | 2001

Overexpression of interferon γ -inducible protein 10 in the liver of patients with type i autoimmune hepatitis identified by suppression subtractive hybridization

Kazuyoshi Nagayama; Nobuyuki Enomoto; Yuka Miyasaka; Masayuki Kurosaki; Cheng-Hsin Chen; Naoya Sakamoto; Mina Nakagawa; Chifumi Sato; Junichi Tazawa; Takaaki Ikeda; Namiki Izumi; Mamoru Watanabe

OBJECTIVE:To clarify gene expression profiles in the liver may elucidate the pathogenesis of type I autoimmune hepatitis (AIH). Using suppression subtractive hybridization (SSH), we identified genes overexpressed in the liver of AIH.METHODS:A small liver biopsy sample from a patient with definite AIH was available to be analyzed in our system. By mixing cDNA synthesized from this sample as a ‘tester’ and cDNA from a normal liver as a ‘driver,’ we subtracted cDNA to enrich genes overexpressed in AIH. After polymerase chain reaction (PCR) amplification and subcloning, we identified subtracted genes by sequencing 50 randomly selected clones.RESULTS:Only one cDNA fragment, which is identical to interferon inducible protein 10 (IP-10), was overexpressed by >10 times in the liver of AIH, as compared with control. We confirmed IP-10 overexpression in all eight patients with AIH by reverse transcription PCR. Immunohistochemical analysis demonstrated increased IP-10 expression in hepatocytes in the liver of AIH. Reverse transcription PCR analysis of 63 liver biopsy samples with various liver diseases revealed that IP-10 expression was significantly higher in AIH (p = 0.025) and chronic hepatitis C (p = 0.0043) than in other liver diseases. Interestingly, the amount of IP-10 mRNA expression was correlated with serum ALT values in AIH (p = 0.0006), but not in chronic hepatitis C (p = 0.43).CONCLUSION:These results indicate the IP-10 expression in the liver might be used as a preferential marker of AIH, and that IP-10 has some pathophysiological roles in the liver damage of AIH.


Hepatology Research | 2003

Amino acid substitutions in PKR-eIF2 phosphorylation homology domain (PePHD) of hepatitis C virus E2 protein in genotype 2a/2b and 1b in Japan and interferon efficacy

Hideki Watanabe; Kazuyoshi Nagayama; Nobuyuki Enomoto; Jun Itakura; Yoko Tanabe; Chifumi Sato; Namiki Izumi; Mamoru Watanabe

Recently, the envelope protein 2 (E2) of hepatitis C virus (HCV) was reported to interact with double stranded RNA-dependent protein kinase (PKR) through an element homologous to the phosphorylation site of PKR and its target, eukaryotic translation initiation factor (eIF) 2alpha (PKR-eIF2alpha phosphorylation homology domain: PePHD). Inhibition of the kinase activity of PKR by this interaction was postulated as a mechanism for the resistance to interferon (IFN) therapy. The aim of this study was to clarify whether the variation of PePHD amino acid sequences affects IFN efficacy in Japanese population. Amino acid sequences of PePHD (aa. 659-670 in genotype1b, aa. 663-674 in genotype 2a and 2b) were determined in randomly selected 112 patients with chronic hepatitis C (genotype 1b; 83 patients, 2a; 14 patients, 2b; 15 patients) prior to IFN monotheray. In 21 out of the 23 genotype 1b sustained responders (SR) (91%) and 55 out of the 60 non-SR (92%), PePHD sequences were identical to that of the HCV-1b consensus sequence. Only two SR showed one amino acid substitution in PePHD, and five non-SR showed amino acid substitutions in PePHD. Among 14 genotype 2a patients, only two SR had one amino acid substitution comparing to the consensus HCV-2a sequence. Likely, only one SR had an amino acid substitution in PePHD among 15 genotype 2b patients. In conclusion, our study revealed no clinical relationship between the amino acid sequence of PePHD and the outcome of IFN therapy. PePHD polymorphism was not suggested to play a role in predicting IFN efficacy.


Virology | 2003

Sequence elements correlating with circulating viral load in genotype 1b hepatitis C virus infection

Hideki Watanabe; Kazuyoshi Nagayama; Nobuyuki Enomoto; Jun Itakura; Yoko Tanabe; Kosei Hamano; Namiki Izumi; Chifumi Sato; Mamoru Watanabe

The correlation between hepatitis C virus (HCV) genomic sequences and circulating HCV RNA levels was assessed to investigate the genetic elements affecting viral load. The interferon sensitivity-determining region (ISDR) sequence and the serum viral load were strongly correlated in 226 patients examined. Analysis of the entire HCV genome from six patients (three with a high and the others with a low viral load) with similar ISDR sequences identified several candidate residues associated with viral load. The amino acid (aa) sequences of these candidate residues and flanking regions in 67 additional patients revealed that only the residue at aa 962 varied significantly between the HCV patients with low and high serum loads (P=0.042). At this position, alanine was observed more frequently in the patients with a high viral load. In conclusion, our results strongly suggest that serum HCV RNA loads are inversely correlated with amino acid substitutions in the ISDR, and aa 962 was identified as a possible second determinant of serum HCV RNA load.


Journal of Viral Hepatitis | 2005

Characteristic sequence changes of hepatitis C virus genotype 2b associated with sustained biochemical response to IFN therapy

Yoko Tanabe; Kazuyoshi Nagayama; Nobuyuki Enomoto; Namiki Izumi; J. Tazawa; Masayuki Kurosaki; Naoya Sakamoto; Chifumi Sato; Mamoru Watanabe

Summary.  In hepatitis C virus (HCV) genotype 2b infection, viral eradication (sustained viral response; sVR) is obtained in about 40% by interferon monotherapy, whereas a considerable proportion of non‐sVR patients exhibit sustained biochemical response (sBR) showing normal biochemical values despite persistent viraemia. However, the mechanism of sBR has not yet been established. In this study, we analysed serial changes in full‐length sequences of HCV genotype 2b before and after interferon (IFN) therapy in five patients with sBR and five with no response (NR; persistent viraemia and abnormal biochemical values after IFN therapy). The overall substitution rate of amino acids in the full‐length HCV genome was higher in the sBR group than in the NR group [2.22 ± 0.48 (10−3 changes/site/year) vs 1.04 ± 0.30: P = 0.002]. When the genetic changes were analysed for individual HCV proteins, the sBR group had significantly higher substitution rates of amino acid in NS4A [8.82 ± 2.80 (10−3 changes/site/year) vs 0: P = 0.001]. These amino acid changes in sBR were mainly located in the binding motifs of HLA class I molecules including those frequently found in the Japanese population. These results demonstrated that the greater amino acid changes of HCV arising during interferon therapy are associated with the establishment of sBR. Although functional significance of these changes awaits further investigation, the finding that amino acid changes in NS4A in sBR patients are mainly located in the HLA class I binding motifs illustrated the potential roles of the escape mutations of HCV genome from CTLs in the decreasing activities of hepatitis in sBR.

Collaboration


Dive into the Kazuyoshi Nagayama's collaboration.

Top Co-Authors

Avatar

Chifumi Sato

Tokyo Medical and Dental University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Yuka Miyasaka

Tokyo Medical and Dental University

View shared research outputs
Top Co-Authors

Avatar

Namiki Izumi

Tokyo Medical and Dental University

View shared research outputs
Top Co-Authors

Avatar

Junichi Tazawa

Tokyo Medical and Dental University

View shared research outputs
Top Co-Authors

Avatar

Mamoru Watanabe

Tokyo Medical and Dental University

View shared research outputs
Top Co-Authors

Avatar

Masayuki Kurosaki

Tokyo Medical and Dental University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Fumiaki Marumo

Tokyo Medical and Dental University

View shared research outputs
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge