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Keisuke Hamasaki

Publications and source records attributed to Keisuke Hamasaki.

17 recordsLinked to original sources
PubMed2003

Analysis of anti-HBs levels in healthcare workers over 10 years following booster vaccination for hepatitis B virus.

In this study, we analyzed anti-HBs levels in 104 Japanese healthcare workers who received three booster HBV surface antigen (HBsAg) vaccines because 80 became anti-HBs-negative at a mean of 2.4 years after the primary vaccination and 24 did not respond to primary vaccination. Of the re-vaccinees, 96% achieved a level of 10 mIU/ml or more of anti-HBs (i.e. seroprotected), 1 month after booster vaccination. Although anti-HBs levels of re-vaccinees decreased as rapidly as those of primary immunized vaccinees, at 10 years post-booster, 64% of re-vaccinees maintained anti-HBs levels at 10 mIU/ml or higher. Our results suggest that the additional three-dose protocol of booster HBsAg vaccination is beneficial in maintaining a seroprotective level of anti-HBs until new immunogenic vaccination protocols are established.

Adult↗
PubMed2003

Hepatic steatosis is a risk factor for hepatocellular carcinoma in patients with chronic hepatitis C virus infection.

BACKGROUND: Hepatic steatosis is one of the histopathologic features of chronic hepatitis C. It was reported recently that the expression of hepatitis C virus (HCV) core protein in transgenic mice induced hepatocellular carcinoma (HCC) in association with steatosis. The objective of this study was to determine the relation between hepatic steatosis and hepatocarcinogenesis in patients with chronic HCV infection. METHODS: The authors studied 161 patients with chronic HCV infection who were diagnosed at Nagasaki University Hospital, Nagasaki, Japan, between January 1980 and December 1999. Age, gender, body mass index (BMI), habitual drinking, diabetes mellitus, serum alanine aminotransferase (ALT) level, HCV serotype, serum level of HCV core protein, interferon (IFN) treatment, hepatic fibrosis inflammation, and hepatic steatosis were studied with regard to their significance in the development of HCC using univariate and multivariate analyses. RESULTS: The cumulative incidence rates of HCC were 24%, 51%, and 63% at 5 years, 10 years, and 15 years, respectively. Multivariate analysis identified hepatic steatosis, together with aging, cirrhosis, and no IFN treatment, as independent and significant risk factors for HCC (P = 0.0135, P = 0.0390, P = 0.0068, and P = 0.0142, respectively). In addition, hepatic steatosis was correlated with BMI, serum ALT levels, and triglyceride levels. CONCLUSIONS: The findings of the current study indicate that hepatic steatosis is a risk factor for HCC in patients with chronic HCV infection. Patients with chronic HCV and hepatic steatosis should be monitored carefully for HCC.

Adult↗
PubMed2003

Short interfering RNA-directed inhibition of hepatitis B virus replication.

RNA interference (RNAi) is the process by which double-stranded RNA directs sequence-specific degradation of mRNA. In mammalian cells, RNAi can be triggered by 21-nucleotide duplexes of short interfering RNA (siRNA). We examined effects of siRNA on hepatitis B virus (HBV) replication. Human hepatoma cells were transfected with HBV DNA and siRNA against HBV-pregenome RNA. Transfection experiments demonstrated that the siRNA reduced the amount of HBV-pregenome RNA and resulted in reduction of the levels of replicative intermediates and viral protein. Our results indicate that siRNA-mediated gene silencing inhibits HBV replication through suppression of viral RNA, which may be useful as a potential therapeutic modality.

Blotting, Northern↗
PubMed2003

Interferon-alpha sensitizes human hepatoma cells to TRAIL-induced apoptosis through DR5 upregulation and NF-kappa B inactivation.

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a member of the TNF superfamily, induces apoptosis in a variety of cancer cells with little or no effect on normal cells. Human hepatoma cells, however, are resistant to TRAIL-induced apoptosis. Since interferon-alpha (IFN-alpha) is capable of enhancing TNF-alpha-induced apoptosis in certain cancer cells, we evaluated the effect of IFN-alpha on TRAIL-induced apoptosis of human hepatoma cells. IFN-alpha pretreatment enhanced TRAIL-induced apoptosis of HuH-7 and Hep3B cells, in which IFN-alpha upregulated the expression of DR5, a death receptor of TRAIL, and downregulated the expression of survivin, which has an antiapoptotic function. In contrast, IFN-alpha did not enhance TRAIL-induced apoptosis of HepG2 cells, in which expression of DR5 and survivin was not affected by IFN-alpha. On the other hand, TRAIL activated NF-kappa B composed of RelA-p50 heterodimer, a key transcription factor regulating cell survival, in HuH-7 and HepG2 cells. However, IFN-alpha pretreatment repressed the TRAIL-mediated activation of NF-kappaB and decreased its transcriptional activity in HuH-7 but not in HepG2 cells. Moreover, IFN-alpha pretreatment clearly augmented TRAIL-mediated caspase-8 activation in HuH-7 cells. Our results suggest that IFN-alpha could sensitize certain human hepatoma cells to TRAIL-induced apoptosis by stimulating its death signaling and by repressing the survival function in these cells.

Apoptosis↗
PubMed2003

Antiangiogenic gene therapy for hepatocellular carcinoma using angiostatin gene.

Recent studies have reported that antiangiogenic gene delivery into cancer cells inhibits growth of certain tumors in vivo. Hepatocellular carcinoma (HCC) is a hypervascular cancer, and antiangiogenic gene therapy might be suitable for HCC. In the present study, we investigated the antiangiogenic effects of angiostatin gene transduction into HCC both in vitro and in vivo. Angiostatin gene was cloned into a pSecTag2B mammalian expression vector to construct pSecTag2B-ANG. pSecTag2B or pSecTag2B-ANG were transfected into an HCC cell line, PLC/PRF/5, and then stable transfectants were obtained by Zeocin selection. pSecTag2B or pSecTag2B-ANG transfection did not alter the expression of vascular endothelial growth factor (VEGF), a potent angiogenic stimulator, or pigment epithelium-derived factor (PEDF), an angiogenic inhibitor, in PLC/PRF/5 cells. However, conditioned media (CM) derived from pSecTag2B-ANG-transfected PLC/PRF/5 cells (CM-ANG) suppressed the proliferation and migration of human umbilical vein endothelial cells (HUVEC) by 35% and 50%, respectively, relative to their effects on nontransfected cells. In in vivo experiments, pSecTag2B-ANG stable transfected (CM-Mock) and nontransfected cells (CM-N) were mixed at various proportions and the mixed cells were subcutaneously implanted into athymic mice. Suppression of tumor growth was noted in mice implanted with angiostatin gene-transfected cells, and such suppression was proportional with the percentage of transfected cells. Analysis of the vascular density in these tumors showed that the tumor growth suppression effect of angiostatin gene correlated with suppression of tumor vascularity. In conclusion, antiangiogenic gene therapy using angiostatin gene is potentially suitable for the treatment of patients with HCC.

Angiogenesis Inhibitors↗
PubMed2003

Immuno-gene therapy with adenoviruses expressing fms-like tyrosine kinase 3 ligand and CD40 ligand for mouse hepatoma cells in vivo.

Introduction of genes encoding immuno-stimulatory cytokines into cancer cells is known to enhance antitumor immunity. CD40 ligand (CD40L, CD154) and fms-like tyrosine kinase 3 ligand (Flt3L) are recently identified cytokines, which have been demonstrated to stimulate antitumor immunity in several cancer models. However little is known about antitumor activity of Ftl3L and CD40L against hepatocellular carcinoma (HCC). In the present study, we constructed replication-defective adenoviruses expressing Flt3L and CD40L and examined their therapeutic efficacy on mouse HCC, MH134 cells. Subcutaneous injection of MH134 cells genetically engineered to express Flt3L and/or CD40L developed tumors in all the syngeneic immunocompetent mice, but tumor growth was significantly delayed as compared to control mice. Partial inhibition of this antitumor effect in athymic nude mice suggests that both innate and adaptive immunity appear to play a role. It was shown by immunodepletion of NK cells with anti-asialo-GM1 antibody that the effector cells involved in innate immunity are NK cells. In a therapeutic setting, however, injection of adenovirus expressing Flt3L or CD40L into pre-established MH134 tumors exhibited no efficacy. These data demonstrate that Flt3L and CD40L induce significant, but only weak, antitumor immunity against MH134 cells presumably through both innate and adaptive immunity. Our results suggest that immuno-gene therapy with Flt3L and CD40L may need adjuvant modalities to achieve strong immune response.

Animals↗
PubMed2002

Involvement of IL-1beta and IL-10 in IFN-alpha-mediated antiviral gene induction in human hepatoma cells.

Crosstalk between interferons (IFNs) and several cytokines is likely to play an important role in viral clearance in chronic hepatitides B and C. We investigated the influence of this phenomenon on IFN-inducible antiviral gene expression in HuH-7 human hepatoma cells. HuH-7 cells were treated with IFN-alpha in the absence or presence of interleukin-1beta (IL-1beta) or IL-10 and the expression of antiviral genes such as 2(')5(')-oligoadenylate synthetase (2(')5(')-OAS) and double-stranded RNA-dependent protein kinase (PKR), as well as activation of signal transducer and activator of transcription 1 (STAT1), a key step for relaying the IFN-alpha signals, was analyzed by Northern blotting, Western blotting, and the reporter gene transfection assay. IL-1beta potentiated IFN-alpha-induced 2(')5(')-OAS and PKR gene expression, similar to expression of the transfected reporter genes containing the IFN-stimulated regulatory elements, while IL-10 suppressed IFN-alpha-stimulated gene expression. With regard to IFN-alpha signaling, IL-1beta enhanced both tyrosine and serine phosphorylation of STAT1 through p38 mitogen-activated protein kinase activation. In contrast, IL-10 inhibited IFN-alpha-mediated tyrosine phosphorylation of STAT1 by induction of a Janus kinase inhibitor, JAB. IL-1beta and IL-10 interact with IFN-alpha to up- and down-regulate antiviral gene expression, respectively, by modulating STAT1 activation induced by IFN-alpha.

2',5'-Oligoadenylate Synthetase↗
PubMed2002

Viral load is a significant prognostic factor for hepatitis B virus-associated hepatocellular carcinoma.

BACKGROUND: Hepatitis B virus (HBV) is closely linked to hepatocellular carcinoma (HCC). The objective of the current study was to identify the factors involved in the prognosis of patients with HBV-associated HCC using multivariate analysis. METHODS: The current study included 74 patients with HBV-associated HCC who were admitted to Nagasaki University Hospital, Nagasaki, Japan, between 1983-1998. Of these, 13 patients underwent surgical tumor resection; 43 patients received nonsurgical treatment with transcatheter arterial embolization, percutaneous ethanol injection, or both; and 18 patients were followed without any active treatment. The significance of the patient's age; gender; history of blood transfusion; alcohol use; serum levels of alanine aminotransferase, alpha-fetoprotein, and HBV-DNA; number and size of liver tumors; clinical stage; and histologic diagnosis of HCC as prognostic factors was evaluated using univariate and multivariate analyses. RESULTS: The 3-year, 5-year, and 10-year postdiagnosis cumulative survival rates were 36%, 21%, and 17%, respectively. Multivariate analysis identified the level of serum HBV-DNA and tumor size at diagnosis as independent and significant prognostic factors (P = 0.0022 and P = 0.0106, respectively). In addition, a low level of viremia was found to be associated with longer survival (P = 0.0057) even in patients who were negative for the hepatitis B e antigen. CONCLUSIONS: The results of the current study suggest that viral load is a useful prognostic marker for HBV-related HCC and that HCC patients with a less favorable course appear either to clear the virus poorly or to have a greater level of virus production.

Adult↗
PubMed2002

p48 Overexpression enhances interferon-mediated expression and activity of double-stranded RNA-dependent protein kinase in human hepatoma cells.

BACKGROUND/AIMS: Double-stranded RNA-dependent protein kinase (PKR) is a key factor involved in interferon (IFN)-induced antiviral actions. Since p48, together with signal transducers and activators of transcription 1 and 2 (STAT1 and STAT2), is an indispensable mediator in IFN-alpha signaling pathways, we investigated the effect of p48 gene transduction on PKR expression and its activity in HuH-7 human hepatoma cells. METHODS: HuH-7 cells were infected or transfected with p48 gene expression adenoviral vector or plasmid vector, respectively, and incubated with or without IFN-alpha, then PKR expression and phosphorylation of alpha-subunit of eukaryotic protein synthesis initiation factor-2 (eIF2alpha) in the cells were examined. In addition, PKR activity inhibiting protein translation was determined by the decrease of chloramphenicol acetyltransferase (CAT) gene translation or alpha-fetoprotein secretion. RESULTS: p48 overexpression itself could not stimulate PKR expression. However, p48 overexpression in combination with interferon-alpha treatment caused a marked increase in PKR expression and augmented the phosphorylation of eIF2alpha, by which the transfected CAT gene translation, as well as the endogenous alpha-fetoprotein synthesis, was blocked without affecting their mRNA levels. CONCLUSIONS: These results suggest that p48 gene transduction may provide a strategy to enhance the IFN-mediated PKR expression and its activity in hepatocytes.

Antiviral Agents↗
PubMed2002

Aspirin and NS-398 inhibit hepatocyte growth factor-induced invasiveness of human hepatoma cells.

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX) activity and are considered to exert antitumor actions in a variety of cancer cells, although the effects are unlikely entirely due to COX inhibition. Because clinical observations suggest that hepatocyte growth factor (HGF) can promote metastasis of hepatoma cells while stimulating tumor invasiveness, we investigated the effect of aspirin and NS-398, a selective COX-2 inhibitor, on HGF-mediated invasiveness of HepG2 human hepatoma cells. HGF stimulated the invasiveness of HepG2 cells in Matrigel cell invasion assay, together with increased expression of matrix metalloproteinase (MMP) 9. Addition of aspirin or NS-398, similar to PD98059, which acts as a specific inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK), an upstream kinase regulating extracellular signal-regulated kinase (ERK)1/2, abrogated such actions of HGF without affecting cell viability. Aspirin and NS-398, in contrast to PD98059, did not suppress ERK1/2 phosphorylation induced by HGF. However, both agents inhibited the kinase activity of ERK1/2 induced by HGF and repressed HGF-induced phosphorylation of 90-kd ribosomal S6 kinase (RSK) and Elk-1, key downstream substrates of ERK1/2, resulting in the suppression of transcriptional activity of Elk-1 as well as nuclear factor kappaB (NF-kappaB) and AP-1, which are involved in MMP-9 gene regulation. In conclusion, our results suggest that aspirin and NS-398 inhibit HGF-induced invasiveness of HepG2 human hepatoma cells through ERK1/2.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2002

Association between nonalcoholic fatty liver, markers of obesity, and serum leptin level in young adults.

OBJECTIVES: The aim of the present study was to clarify the risk factors for nonalcoholic fatty liver in young adults. METHODS: One thousand two hundred two students, aged 18-21 yr, received matriculation health examinations, including measurements of body mass index and percent body fat and determination of serum levels of ALT at Nagasaki University in 1998. One hundred twenty-nine were found to have borderline or elevated levels of serum ALT, and 105 of the 129 students (75 men and 30 women) were subjected to further analysis for the presence of fatty liver using ultrasonography, by which both the degree of steatosis and the abdominal wall fat index (AFI) corresponding to the ratio of visceral to s.c. adipose tissue (V/S ratio) were evaluated, in addition to determination of the serum level of leptin. RESULTS: Of 105 students, 74 (70%) had fatty liver. The incidence of moderately to severely fatty liver was significantly higher in men than in women. In parameters related to obesity, the close correlation between body mass index and percent body fat was observed in both sexes. The serum level of leptin correlated well with percent body fat and AFI (V/S ratio) in women, whereas it did not correlate with AFI (V/S ratio) in men. Multiple logistic regression analysis indicated that AFI (V/S ratio) was the only independent risk factor for fatty liver in both sexes. CONCLUSIONS: These results suggest that visceral fat distribution is a key risk factor for nonalcoholic fatty liver in young adults.

Adolescent↗
PubMed2002

Influence of interleukin-10 gene promoter polymorphisms on disease progression in patients chronically infected with hepatitis B virus.

OBJECTIVES: The role of host genetic factors in chronic hepatitis B virus (HBV) infection is not fully understood. We studied the influence of tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) gene promoter polymorphisms on disease progression in HBV carriers. METHODS: The sample population included 213 Japanese HBV carriers and 52 healthy volunteers. Of 213 HBV carriers, 66 were considered to be asymptomatic carriers based on the sustained normalization of serum ALT together with seropositivity for the antibody to hepatitis B e antigen (anti-HBe), and 147 were found to have chronic progressive liver disease including cirrhosis. Five biallelic polymorphisms in the TNF-alpha gene promoter and three biallelic polymorphisms in the IL-10 gene promoter were analyzed by polymerase chain reaction in combination with direct sequencing or restriction fragment length polymorphism assay. RESULTS: Allelic distributions of both gene promoters were not significantly different between HBV carriers and healthy volunteers. In HBV carriers, the TNF-alpha gene promoter polymorphisms were not linked to disease progression. In contrast, allelic frequencies of T and A at positions -819 and -592, respectively, in the IL-10 gene promoter, as well as the frequencies of ATA haplotype at positions -1082/-819/-592 (which is characterized with low capacity for IL-10 production), were significantly higher in asymptomatic carriers than in patients with chronic progressive liver disease. Even after adjusting for individuals positive for anti-HBe, such a relationship could be found between the two groups. CONCLUSION: In chronic HBV infection, inheritance of the IL-10 gene promoter polymorphisms is involved in a host genetic factor that is relevant to disease progression.

Adult↗
PubMed2002

Amyloid a protein amyloidosis in a patient with plasma cell dyscrasia.

We report a 59-year-old man who was found to have plasma cell dyscrasia and amyloid A protein (AA) amyloidosis during the follow-up period of chronic inactive hepatitis C. Clinical manifestations such as swallowing disturbance, proteinuria and leg edema were associated with AA amyloid deposits in his tongue and kidneys. Although the relationship between these two diseases remains to be determined, the ability of peripheral blood mononuclear cells to degradate serum amyloid A protein was apparently reduced in this patient, compared with normal volunteers. This would, in part, account for the AA amyloid deposition in this patient.

Amyloidosis↗
PubMed2002

[Hepatitis B].

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Age Factors↗
PubMed2002

Transactivation of human alpha-fetoprotein gene by X-gene product of hepatitis B virus in human hepatoma cells.

The X-gene product of hepatitis B virus (HBX) modulates a variety of viral and cellular genes relevant to hepatocarcinogenesis, where alpha-fetoprotein (AFP) is produced by hepatoma cells. In the present study, the possible mechanism by which HBX regulates AFP expression was investigated using three human hepatoma cells, HepG2, HuH-7 and Hep3B, which are known to contain the wild-type, the mutant-type and the deletion of p53, respectively. Transfection with the HBX expression vector stimulated the co-transfected AFP reporter gene expression in HepG2 cells and HuH-7 cells, but not in Hep3B cells. Transfection with the p53 expression vector repressed the AFP reporter gene expression in all three hepatoma cells, while overexpression of HBX counteracted the p53-induced repression. In addition, a G-->A substitution at nucleotide -119 in the AFP promoter sequence abrogated the stimulatory effect of HBX on the AFP promoter in HepG2 cells. These results suggest that HBX interacts with p53 to up-regulate AFP gene transcription probably by restoration of the p53-mediated repression of the AFP promotor activity.

Carcinoma, Hepatocellular↗