Publications by authors named "Kazuaki Chayama"

Experimental and clinical studies have suggested atherosclerotic effects of uric acid (UA) on vascular smooth muscle cells (VSMCs). Nitroglycerine-induced vasodilation (NID), a control test for flow-mediated vasodilation, can be used as a possible marker of VSMC dysfunction. However, there is little information on the association between UA and NID.

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Background: Hepatitis C (HCV) is a virus that causes chronic liver disease, end-stage cirrhosis, and liver cancer, yet most infected individuals remain undiagnosed or untreated. Kenya is a country located in Sub-Saharan Africa (SSA) where the prevalence of HCV remains high but with uncertain disease burden due to little population-based evidence of the epidemic. We aimed to highlight the HCV disease burden in Kenya with a summary of the available data.

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Chronic liver disease and cancer are global health challenges. The role of the circadian clock as a regulator of liver physiology and disease is well established in rodents, however, the identity and epigenetic regulation of rhythmically expressed genes in human disease is less well studied. Here we unravel the rhythmic transcriptome and epigenome of human hepatocytes using male human liver chimeric mice.

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Background & Aims: Liver fibrosis is the major driver of hepatocellular carcinoma and liver disease-related death. Approved antifibrotic therapies are absent and compounds in development have limited efficacy. Increased TGF-β signaling drives collagen deposition by hepatic stellate cells (HSCs)/myofibroblasts.

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Article Synopsis
  • Recent studies show that pegylated interferon (IFN) treatments can significantly reduce hepatitis D virus (HDV) levels.
  • The research involved testing the effectiveness of IFNλ and IFNα in humanized mice models, with some mice infected with both hepatitis B virus (HBV) and HDV, while others were infected with HDV after HBV.
  • Results indicated that IFNα treatment resulted in a more substantial decrease in HBV and HDV levels compared to IFNλ, highlighting the need for further research on immune responses in treating these viruses.
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Article Synopsis
  • * The study involved 639 patients who did not develop HCC for over 7 years and 46 who did within that time; the model achieved an accuracy of 81.0% and showed effective validation results.
  • * The deep learning model could detect early signs of HCC even in patients with mild fibrosis by analyzing key pathological features, suggesting its potential for improving early diagnosis.
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Upstroke time (UT) and percentage of mean arterial pressure (%MAP) at the ankle have been shown to serve as atherosclerotic markers. The purpose of this study was to directly compare the diagnostic accuracy of UT with that of %MAP for clinical coronary artery disease (CAD) in subjects with a normal ankle-brachial index (ABI) in both legs. We measured UT and %MAP in 1953 subjects with a normal ABI.

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Context: A Body Shape Index (ABSI) has been reported to have associations with cardiovascular risk factors. However, there is no information on the association between ABSI and incidence of cardiovascular events.

Methods: We investigated the associations between ABSI and first major cardiovascular events (death from cardiovascular disease, nonfatal acute coronary syndrome, and nonfatal stroke) in 1857 subjects from the database of Flow-Mediated Dilation Japan registry and from Hiroshima University Vascular Function registry.

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Chronic infection with the hepatitis B virus (HBV) induces progressive hepatic impairment. Achieving complete eradication of the virus remains a formidable challenge. Cytotoxic T lymphocytes, specific to viral antigens, either exhibit a numerical deficiency or succumb to an exhausted state in individuals chronically afflicted with HBV.

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The proto-oncogene MYCN expression marked a cancer stem-like cell population in hepatocellular carcinoma (HCC) and served as a therapeutic target of acyclic retinoid (ACR), an orally administered vitamin A derivative that has demonstrated promising efficacy and safety in reducing HCC recurrence. This study investigated the role of MYCN as a predictive biomarker for therapeutic response to ACR and prognosis of HCC. MYCN gene expression in HCC was analyzed in the Cancer Genome Atlas and a Taiwanese cohort (N = 118).

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We developed a fatty liver mouse model using human hepatocyte chimeric mice. As transplanted human hepatocytes do not respond to mouse growth hormone (GH) and tend to accumulate fat, we hypothesized that addition of human GH would alter lipid metabolism and reduce accumulation of fat in the liver even when fed a high-fat diet. Six uPA/SCID chimeric mice were fed a high-fat GAN diet to induce fatty liver while six were fed a normal CRF1 diet, and GH was administered to three mice in each group.

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Background And Aim: While several predictive models for the development of hepatocellular carcinoma (HCC) have been proposed, including those for patients with chronic hepatitis C virus (HCV) infection who have achieved sustained virologic response (SVR), the best model may differ between regions. We compared the ability of six reported models to stratify the risk of post-SVR HCC in Japan, where rigorous surveillance and early detection of HCC is common.

Methods: A total of 6048 patients with no history of HCC who achieved SVR by oral direct-acting antiviral drugs were enrolled in this nationwide study.

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Previous infection with hepatitis B virus (HBV), which is assessed by HBV core antibody (HBcAb) or surface antibody (HBsAb) titres, has reportedly been associated with an increased risk of developing hepatocellular carcinoma (HCC). We investigated the influence of previous HBV infection on the incidence of HCC in patients with hepatitis C virus (HCV) infection who achieved eradication of HCV, that is sustained virologic response (SVR). Both HBcAb and HBsAb were measured in a total of 1214 patients with HCV infection who had not been coinfected with HBV, as determined by both negative HBs antigen and HBV DNA, and in whom SVR was confirmed.

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Cardiovascular mortality has been shown to vary seasonally. However, it has not been determined whether vascular function is affected by the season. The purpose of this study was to investigate the associations of vascular function with season and outdoor temperature.

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Article Synopsis
  • - The study aimed to understand how serum small dense low-density lipoprotein cholesterol (sdLDL-C) and triglyceride (TG) levels relate to cardiovascular events in patients with coronary artery disease (CAD) and type 2 diabetes who are on statins.
  • - Participants were categorized into four groups based on their sdLDL-C and TG levels, with cardiovascular events tracked over a median of 1419 days, resulting in 34 events during the study.
  • - Results indicated that patients with sdLDL-C levels of 40.0 mg/dL or higher faced a greater risk of cardiovascular events, even when their TG levels were below 150 mg/dL, highlighting the residual risk present despite statin treatment.
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Background: Lenvatinib, a multiple receptor tyrosine kinase inhibitor, might exert antitumor effects via tumor immune modulation. However, changes in the tumor immune microenvironment induced by lenvatinib are poorly understood. We investigated the effect of lenvatinib on immune features in clinical samples from patients with hepatocellular carcinoma.

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The percentage of mean arterial pressure (%MAP) is the height of the mean arterial waveform divided by the peak amplitude of the waveform of pulse volume recording. The purpose of this study was to determine whether the cutoff value of 45% for %MAP at the ankle, which is recommended for the diagnosis of lower extremity artery disease, in combination with ankle-brachial index (ABI) is useful for detecting patients with clinical coronary artery disease (CAD) and investigate the optimal cutoff value of %MAP to diagnose patients with CAD. We measured ABI and %MAP in 2213 subjects (mean age: 61.

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It has been reported that high intensity in the hepatobiliary (HB) phase of Gd-EOB-DTPA-enhanced MRI (EOB-MRI) is associated with an immune-cold microenvironment in HCC. The aim of this study is to reveal whether non-high-intensity HCCs are homogeneous with respect to the immune microenvironment and to investigate the predictive ability of EOB-MRI for the response to atezolizumab + bevacizumab therapy (Atezo/Bev). The association between differences in stepwise signal intensity of HB phase and molecular subtypes and somatic mutations associated with the immune microenvironment was investigated in 65 HCC patients (cohort 1).

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Hepatitis B virus (HBV) infection kinetics in immunodeficient mice reconstituted with humanized livers from inoculation to steady state is highly dynamic despite the absence of an adaptive immune response. To recapitulate the multiphasic viral kinetic patterns, we developed an agent-based model that includes intracellular virion production cycles reflecting the cyclic nature of each individual virus lifecycle. The model fits the data well predicting an increase in production cycles initially starting with a long production cycle of 1 virion per 20 hours that gradually reaches 1 virion per hour after approximately 3-4 days before virion production increases dramatically to reach to a steady state rate of 4 virions per hour per cell.

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Aim: There are few reports on the prognosis of liver-related events in Japanese patients with nonalcoholic fatty liver disease (NAFLD). We undertook an observational study to compare the prognosis between fibrotic and nonfibrotic groups in Japanese NAFLD patients.

Methods: Prognosis in 393 NAFLD patients who underwent liver biopsy between April 2013 and April 2015 at multiple centers were investigated.

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Hepatitis B virus (HBV) infects the liver and is a major risk factor for liver cirrhosis and hepatocellular carcinoma. Approaches for an effective cure are thwarted by limited knowledge of virus-host interactions. Herein, we identified SCAP as a novel host factor that regulates HBV gene expression.

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Aims: Hepatitis C virus (HCV) infection among drug users presents an important public health problem; however, little recognition and few approaches to address this issue in Japan. This study was conducted to investigate the current disease status by assessing anti-HCV antibody (Ab) seroprevalence among people who inject drugs (PWIDs) and people who use drugs (PWUDs) in Hiroshima, Japan.

Methods: This study was a psychiatric single-site chart review in patients with drug abuse problems in the Hiroshima region.

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Article Synopsis
  • Heart failure (HF) is linked to issues with the endothelium, and this study focuses on how vascular function is affected in patients with wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM).
  • Researchers measured various indicators of vascular health in 22 ATTRwt-CM patients compared to matched controls, finding that flow-mediated vasodilation (FMD) was significantly higher in ATTRwt-CM patients.
  • Despite higher FMD, no significant differences were found in nitroglycerine-induced vasodilation, arterial thickness, or stiffness between the two groups, suggesting that endothelial function is preserved in ATTRwt-CM patients possibly due to elevated BNP levels.
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