Publications by authors named "Katsumi Aoyagi"

Introduction And Objectives: We aimed to compare the usefulness of the ultra-high-sensitivity hepatitis B surface antigen (iTACT-HBsAg), high-sensitivity hepatitis B core-related antigen (iTACT-HBcrAg), and anti-HBs assays in determination of cessation of nucleot(s)ide analogue (NA) treatment to prevent against hepatitis B virus (HBV) reactivation.

Patients And Methods: Twenty-two patients who developed HBV reactivation under immunosuppressive therapy or chemotherapy and had been administered NA and subsequently discontinued were enrolled. The stored serum samples taken at NA cessation were applied to iTACT-HBsAg (lower limit of detection; 0.

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This study presents a retrospective assessment of the diagnostic performance of the newly developed hepatitis B core-related antigen rapid diagnostic test (HBcrAg-RDT) in detecting plasma samples with elevated hepatitis B virus (HBV) DNA levels (≥200,000 IU/ml) in Yaoundé, Cameroon. Samples were collected consecutively from treatment-naïve adults living with HBV between January 1, 2021, and June 30, 2023. Analyzing 146 samples from participants with a median age of 36 years, the HBcrAg-RDT exhibited a sensitivity of 97.

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Background: Glial fibrillary acidic protein (GFAP) is an important biomarker for neuroinflammatory conditions. Recently, advancements in the treatment of neurological diseases have highlighted the increasing importance of biomarkers, creating a demand for accurate and simple measurement systems for GFAP levels, which are essential for both research and clinical applications. This study presents the development and validation of a novel fully automated immunoassay for the quantitative determination of GFAP levels in biological samples.

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Objectives: Human thyroglobulin (Tg) is widely used as a tumor marker for recurrence and metastasis of differentiated thyroid cancer (DTC). Currently, serum Tg values are measured using second-generation sandwich immunoassays (2nd-IMA). However, interference by endogenous autoantibodies to thyroglobulin (TgAbs) can lead to false-negative results or falsely low Tg values.

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Objectives: Cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD) are well-established in research settings, but their use in routine clinical practice remains a largely unexploited potential. Here, we examined the relationship between CSF biomarkers, measured by a fully automated immunoassay platform, and brain β-amyloid (Aβ) deposition status confirmed by amyloid positron emission tomography (PET).

Methods: One hundred ninety-nine CSF samples from clinically diagnosed AD patients enrolled in a clinical study and who underwent amyloid PET were used for the measurement of CSF biomarkers Aβ 1-40 (Aβ40), Aβ 1-42 (Aβ42), total tau (t-Tau), and phosphorylated tau-181 (p-Tau181) using the LUMIPULSE system.

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Backgrounds: A fully automated, novel, high-sensitivity hepatitis B core-related antigen assay (iTACT-HBcrAg) has been developing. The purpose of this study is to evaluate the efficacy of measuring HBcrAg, using that assay, to diagnose HBV reactivation in a multi-center setting, compared with ultra-high-sensitivity HBsAg (iTACT-HBsAg) and HBV DNA assays.

Methods: Forty-four patients with HBV reactivation from 2008 to 2020 were enrolled in four hospitals.

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Aims: To prevent hepatitis B virus (HBV) reactivation-related hepatitis, we examined the clinical usefulness of a highly sensitive HB core-related antigen (iTACT-HBcrAg) assay in patients with resolved HBV infection after nucleos(t)ide analog (NA) treatment for HBV reactivation.

Methods: We retrospectively analyzed 27 patients with resolved HBV infection who experienced HBV reactivation (defined as HBV DNA levels of 1.3 log IU/ml or more), and who received systemic chemotherapies for hematological malignancies between 2008 and 2020.

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Background: Recently, second-generation thyroglobulin (Tg) sandwich immunoassays have been used in clinical laboratories to measure the serum Tg levels, which is a tumor marker used to monitor postoperative patients with differentiated thyroid cancers. However, these immunoassays are often subject to Tg autoantibody (TgAb) interference. TgAb interference is inevitable for almost all Tg immunoassays, resulting in unreliable Tg measurement values of TgAb-positive samples.

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Background & Aims: A fully automated, novel high-sensitivity hepatitis B core-related antigen assay (iTACT-HBcrAg) has been developed. We demonstrate the clinical utility of iTACT-HBcrAg for monitoring chronic hepatitis B (CHB) and for the early detection of HBV reactivation.

Methods: After fundamental assessments, the clinical performance of iTACT-HBcrAg was compared with other HBV markers.

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We evaluated the rapid immunochromatographic test for severe acute respiratory coronavirus 2 (SARS-CoV-2) antigen detection using 16 saliva specimens collected from 6 COVID-19 hospitalized patients, and detected N-antigen in 4 of 7 RT-PCR positive specimens. This POCT detected SARS-CoV-2 antigen in saliva and would be useful for COVID-19 diagnosis.

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Aim: Type IV collagen 7S (T4C7S) is a valuable biomarker for detecting liver fibrosis in patients with nonalcoholic fatty liver disease (NAFLD). The conventional T4C7S measurement via radioimmunoassay (T4C7S RIA) has shortcomings of radioisotope usage and longer assay periods. We compared T4C7S RIA with a newly developed, fast T4C7S chemiluminescent enzyme immunoassay (T4C7S CLEIA) and examined the diagnostic accuracies of and correlation between the two techniques.

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Background: To eliminate hepatitis B virus (HBV) infection, it is essential to scale up testing and treatment. However, conventional tools to assess treatment eligibility, particularly nucleic acid testing (NAT) to quantify HBV DNA, are hardly available and affordable in resource-limited countries. We therefore assessed the performance of a novel immunoassay, hepatitis B core-related antigen (HBcrAg), as an inexpensive (US$ <15/assay) alternative to NAT to diagnose clinically important HBV DNA thresholds (≥2000, ≥20 000, and ≥200 000 IU/mL) and to select patients for antiviral therapy in Africa.

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Aim: Recently, the measurement of hepatitis B surface antigen and anti-hepatitis B core antigen (HBcAb) and/or anti-hepatitis B surface antigen has been recommended before various therapies to identify patients at risk of hepatitis B virus (HBV) reactivation. However, a recent study reported that HBV reactivation occurred in HBcAb-negative patients, indicating that it is challenging to identify patients with a history of HBV infection using conventional HBcAb reagent. We developed a highly sensitive HBcAb (HBcAb-HS) assay for reducing the risk of HBV reactivation.

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Background: Hepatitis B surface antigen (HBsAg) is used as a clinical marker of hepatitis B virus (HBV) infection. However, conventional HBsAg assays have so far failed to accurately detect HBsAg in blood because of interference by patient-derived antibodies against HBsAg (HBsAb).

Methods: We developed a novel, fully automated assay system that can detect total HBsAg in blood, including antigens complexed with HBsAb.

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Background: Small molecules classified as haptens are generally measured by competitive immunoassay, which is theoretically inferior to noncompetitive sandwich immunoassay in terms of sensitivity and specificity. We created a method for developing sandwich immunoassays to measure haptens on the basis of antimetatype antibodies.

Methods: We generated antimetatype monoclonal antibodies against a hapten-antibody immunocomplex using an ex vivo antibody development system, the Autonomously Diversifying Library (ADLib) system.

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