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23
result(s) for
"Horikawa, Kazuo"
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Cellular and humoral immunity and IgG subclass distribution after omicron XBB.1.5 monovalent vaccination in Japan
2024
Up to seven doses of coronavirus disease 2019 (COVID-19) mRNA vaccines (BNT162b2) were administered to Japanese healthcare workers, until February 2024. The monovalent Omicron XBB.1.5 vaccine (hereafter called XBB.1.5 vaccine) was used for dose 7.
Although the XBB.1.5 vaccine has been reported to induce a robust increase in neutralizing antibodies against the currently circulating Omicron variant BA.2.86, little is known about its serological effects in Japan, where the BNT162b2 mRNA vaccine is the most frequently administered in the world.
Twenty-five recipients of the XBB.1.5 vaccine, categorized as seronegative (n = 18) or seropositive (n = 7) based on their recent history of COVID-19, were analyzed. Neutralizing antibody titers against Omicron subvariants, receptor binding domain (RBD) IgG levels, IgG subclass distribution, and T-cell responses were assessed.
We found a significant increase in neutralizing antibody titers against XBB.1.5 and BA.2.86 variants following XBB.1.5 vaccination, particularly in seropositive individuals. No significant change in total RBD IgG levels was observed, indicating efficient induction of antibodies targeting regions outside the RBD by XBB.1.5 vaccination. IgG subclass analysis demonstrated no significant subclass switching after vaccination. T-cell responses against the virus were comparable between seropositive and seronegative groups.
The study suggests that XBB.1.5 vaccination enhances humoral immunity against Omicron variants without significant IgG subclass switching. However, some individuals with low pre-vaccination IgG titers did not exhibit increased antibody levels post-vaccination, raising concerns about potential immune tolerance.
Journal Article
Humoral and Cell-Mediated Immunity Against SARS-CoV-2 in Healthcare Personnel Who Received Multiple mRNA Vaccines: A 4-Year Observational Study
2025
Background/Objectives: The long-term effects of multiple updated vaccinations against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have not been clarified. Humoral or cellular immunity dynamics in healthcare workers for four years were analyzed. Methods: Blood samples were collected at five time points from April 2021 to January 2024. Humoral immunity was analyzed using the 50% neutralizing titer (NT50) against the original Omicron XBB and Omicron BA.2.86 strains and cellular immunity were analyzed using the ELISpot interferon-gamma releasing assay. NT50s and the spot-forming count (SFC) of the ELISpot assay were compared in the SARS-CoV-2 Omicron XBB-, Omicron-infected, and uninfected subjects. Results: 32 healthcare workers (median age, 47 years) who received 3–7 vaccine doses were enrolled. The NT50s against the original strain decreased after the second vaccination but were maintained after the third vaccine dose. NT50s against the Omicron XBB and BA.2.86 strains were detected before the Omicron vaccine was introduced and increased following the updated vaccination. The NT50s against the Omicron XBB and BA.2.86 strains were elevated after natural infection by the Omicron strain, albeit without differences compared with the findings in uninfected subjects. Multivariate regression analysis revealed no confounder that affected the antibody titer against the BA.2.86 strain at the fifth blood sampling. The median number of SFCs ranged from 78 to 208 after the first two doses. Conclusions: Multiple vaccinations induced the production of antibodies with divergent activity against emerging mutant strains and enhanced protective effects against the original strain. This finding supported the importance of updated vaccination.
Journal Article
Enhanced Detection of SARS-CoV-2 Using Platinum-Decorated Poly(2-vinylpyridine) Nanoparticle-Based Lateral Flow Immunoassay
by
Ryo, Akihide
,
Enomoto, Yasushi
,
Horikawa, Kazuo
in
Antigens
,
Communicable diseases
,
Coronaviruses
2025
Rapid and high-throughput diagnostic methods are essential for controlling the spread of infectious diseases, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Lateral flow immunoassay (LFIA) strips provide a cost-effective and user-friendly platform for point-of-care testing. However, the sensitivity of conventional LFIA kits is often limited by the performance of their detection probes. This study reports a highly sensitive LFIA strip for detecting the SARS-CoV-2 nucleocapsid (NP) protein using platinum-decorated poly(2-vinylpyridine) nanoparticles (Pt-P2VPs) as probes.
Monoclonal antibodies against SARS-CoV-2 NP were conjugated with Pt-P2VPs and incorporated into LFIA strips. The test line was coated with anti-SARS-CoV-2 NP monoclonal antibody, and the control line with goat anti-mouse IgG. Recombinant proteins, viral strains, and nasopharyngeal swab specimens from patients were used to evaluate assay performance, with reverse transcription polymerase chain reaction (RT-PCR) as the reference standard. Diagnostic accuracy was assessed using nonparametric statistical tests.
Pt-P2VP-based LFIA strips enabled sensitive detection of recombinant NP and inactivated SARS-CoV-2, with minimal cross-reactivity. In 200 clinical specimens (100 PCR-negative and 100 PCR-positive), the assay achieved 74% sensitivity and 100% specificity, with strong correlation to viral RNA load. Compared with conventional LFIA kits, Pt-P2VP strips demonstrated superior sensitivity at lower viral loads.
Pt-P2VPs represent a promising probe material for enhancing LFIA performance and may facilitate the development of rapid, sensitive, and scalable immunoassays for infectious disease diagnostics in biomedical applications.
Journal Article
Structure and Function of Potential Glycosylation Sites of Dynactin-Associated Protein dynAP
by
Tsuda, Eisuke
,
Nakamura, Toshinobu
,
Togo, Yuki
in
Amino acid composition
,
Amino acids
,
Clusters
2022
Overexpression of human dynactin-associated protein (dynAP) transforms NIH3T3 cells. DynAP is a single-pass transmembrane protein with a carboxy-terminal region (amino acids 135–210) exposed to the outside of the cell possessing one potential N-glycosylation site (position 143) and a distal C-terminal region (residues 173–210) harboring a Thr/Ser-rich (T/S) cluster that may be O-glycosylated. In SDS–PAGE, dynAP migrates anomalously at ~ 45 kDa, much larger than expected (22.5 kDa) based on the amino acid composition. Using dynAP mutants, we herein showed that the T/S cluster region is responsible for the anomalous migration. The T/S cluster region is required for transport to the cytoplasmic membrane and cell transformation. We produced and purified the extracellular fragment (dynAP135–210) in secreted form and analyzed the attached glycans. Asn143 displayed complex-type glycosylation, suggesting that oligosaccharide transferase may recognize the NXT/S sequon in the secretory form, but not clearly in full-length dynAP. Core I-type O-glycosylation (Gal-GalNAc) was observed, but the mass spectrometry signal was weak, clearly indicating that further studies are needed to elucidate modifications in this region.
Journal Article
Identification of Putative Serum Autoantibodies Associated with Post-Acute Sequelae of COVID-19 via Comprehensive Protein Array Analysis
2025
Post-acute sequelae of SARS-CoV-2 infection (PASC), commonly known as “Long COVID”, represents a significant clinical challenge characterized by persistent symptoms following acute COVID-19 infection. We conducted a comprehensive retrospective cohort study to identify serum autoantibody biomarkers associated with PASC. Initial screening using a protein bead array comprising approximately 20,000 human proteins identified several candidate PASC-associated autoantibodies. Subsequent validation by enzyme-linked immunosorbent assay (ELISA) in an expanded cohort—consisting of PASC patients, non-PASC COVID-19 convalescents, and pre-pandemic healthy controls—revealed two promising biomarkers: autoantibodies targeting PITX2 and FBXO2. PITX2 autoantibodies demonstrated high accuracy in distinguishing PASC patients from both non-PASC convalescents (area under the curve [AUC] = 0.891) and healthy controls (AUC = 0.866), while FBXO2 autoantibodies showed moderate accuracy (AUC = 0.762 and 0.786, respectively). Notably, the levels of these autoantibodies were associated with several PASC symptoms, including fever, dyspnea, palpitations, loss of appetite, and brain fog. The identification of PITX2 and FBXO2 autoantibodies as biomarkers not only enhances our understanding of PASC pathophysiology but also provides promising candidates for further investigation.
Journal Article
Single-nucleotide polymorphisms in HORMAD1 may be a risk factor for azoospermia caused by meiotic arrest in Japanese patients
by
Toshinobu Miyamoto Aldra Tsujimura Yasushi Miyagawa Eitetsu Koh Mikio Namiki Michiharu Horikawa Yasuaki Saijo Kazuo Sengoku
in
Asian Continental Ancestry Group - genetics
,
Azoospermia - genetics
,
Cell Cycle Proteins - genetics
2012
Genetic mechanisms are implicated as a cause of some male infertility, yet are poorly understood. Meiosis is unique to germ cells and essential for reproduction. The synaptonemal complex is a critical component for chromosome pairing, segregation and recombination. Hormadl is essential for mammalian gametogenesis as knockout male mice are infertile. Hormadl-deficient testes exhibit meiotic arrest in the early pachytene stage and synaptonema! complexes cannot be visualized. To analyze the hypothesis that the human HORMAD1 gene defects are associated with human azoospermia caused by meiotic arrest, mutational analysis was performed in all coding regions by direct sequence analysis of 30 Japanese men diagnosed with azoospermia resulting from meiotic arrest. By the sequence analysis, three polymorphism sites, Single Nucleotide Polymorphism 1 (c. 163A〉G), SNP2 (c. 501T〉G) and SNP3 (c. 918C〉T), were found in exons 3, 8 and 10. The 30 patients with azoospermia and 80 normal pregnancy-proven, fertile men were analyzed for HORMAD1 polymorphisms. Both SNP1 and SNP2 were associated with human azoospermia caused by complete early meiotic arrest (P〈0.0S). We suggest that the HORMAD1 has an essential meiotic function in human spermatogenesis.
Journal Article
Magnetic biomonitoring of roadside pollution in the restricted Midagahara area of Mt. Tateyama, Toyama, Japan
by
Kawasaki, Kazuo
,
Sakai, Hideo
,
Horikawa, Keiji
in
Air pollution
,
Anthropogenic factors
,
Aquatic Pollution
2017
Magnetic biomonitoring techniques and in situ topsoil magnetic susceptibility measurements have been shown to be rapid, cost-effective, and useful methods for investigating roadside pollution. However, combustible vegetation in samples makes it very difficult to use them in high-temperature magnetic experiments although the thermal alteration of spontaneous magnetization is a fundamental magnetic property and can be used to identify reliably the magnetic minerals. Here, we report the first magnetic biomonitoring results of dust deposited on plant leaves along the Tateyama-Kurobe Alpine route at the highly protected Midagahara wetland areas of Mt. Tateyama in Toyama, Japan. In-field magnetic susceptibility from 15 sites (161 points) shows higher susceptibilities near the roadside. Dust deposited on the leaves of
Sasa kurilensis
, or dwarf bamboo, has been wiped off at 12 sites (64 samples) with a commercial ethanol wipe sheet or silica wool damped in ethanol and subjected to rock magnetic analyses. Thermomagnetic remanence curves and low-temperature behaviors for samples collected near the roadside using silica wool show clearly that the main magnetic mineral in the dust is partially oxidized magnetite. Further, detailed rock magnetic analyses and elemental analyses of leaves in the study area indicate that (a) the magnetic mineralogy on leaves’ surface is consistent throughout the study area and (b) higher saturation isothermal remanent magnetization intensities as well as higher concentrations of Pb, Fe, Cr, and Y are observed near the roadside, i.e., the closer to the roadside, the more anthropogenic materials, including partially oxidized magnetite, are present. Also, microscopic observations show the lack of spherical grains, indicating that dust on the roadside leaves is derived from passing vehicle rather than industrial process. Both rock magnetic and geochemical results show that
S. kurilensis
would be an excellent candidate for investigating air pollution. Also, the proposed wiping-off method of collecting dust from plant surfaces is an effective non-destructive method that can be applied even in highly restricted collection areas, because detailed magnetic mineralogy, including superparamagnetic minerals, could be determined with the use of silica wool for use in both high- and low-temperature experiments.
Journal Article
Variants in KCNQ1 are associated with susceptibility to type 2 diabetes mellitus
by
Park, Kyong Soo
,
Tanahashi, Toshihito
,
Maeda, Eiichi
in
Agriculture
,
Alzheimer's disease
,
Animal Genetics and Genomics
2008
Masato Kasuga and colleagues and Shiro Maeda and colleagues each report the independent identification of SNPs in
KCNQ1
associated with type 2 diabetes in the Japanese population. Each group replicated the associations in other populations of East Asian and European descent.
We carried out a multistage genome-wide association study of type 2 diabetes mellitus in Japanese individuals, with a total of 1,612 cases and 1,424 controls and 100,000 SNPs. The most significant association was obtained with SNPs in
KCNQ1
, and dense mapping within the gene revealed that rs2237892 in intron 15 showed the lowest
P
value (6.7 × 10
−13
, odds ratio (OR) = 1.49). The association of
KCNQ1
with type 2 diabetes was replicated in populations of Korean, Chinese and European ancestry as well as in two independent Japanese populations, and meta-analysis with a total of 19,930 individuals (9,569 cases and 10,361 controls) yielded a
P
value of 1.7 × 10
−42
(OR = 1.40; 95% CI = 1.34–1.47) for rs2237892. Among control subjects, the risk allele of this polymorphism was associated with impairment of insulin secretion according to the homeostasis model assessment of β-cell function or the corrected insulin response. Our data thus implicate
KCNQ1
as a diabetes susceptibility gene in groups of different ancestries.
Journal Article
Solidified magma reservoir derived from active source seismic experiments in the Aira caldera, southern Kyushu, Japan
2023
The Aira caldera, located in southern Kyushu, Japan, originally formed 100 ka, and its current shape reflects the more recent 30 ka caldera-forming eruptions (hereafter, called the AT eruptions). This study aimed to delineate the detailed two-dimensional (2D) seismic velocity structure of the Aira caldera down to approximately 15 km, by means of the travel-time tomography analysis of the seismic profile across the caldera acquired in 2017 and 2018. A substantial structural difference in thickness in the subsurface low-velocity areas in the Aira caldera between the eastern and western sides, suggest that the Aira caldera comprises at least two calderas, identified as the AT and Wakamiko calderas. The most interesting feature of the caldera structure is the existence of a substantial high-velocity zone (HVZ) with a velocity of more than 6.8 km/s at depths of about 6–11 km beneath the central area of the AT caldera. Because no high ratio of P- to S-wave velocity zones in the depth range were detected from the previous three-dimensional velocity model beneath the AT caldera region, we infer that the HVZ is not an active magma reservoir but comprises a solidified and cool remnant. In addition, a poorly resolved low-velocity zone around 15 km in depth suggests the existence of a deep active magma reservoir. By superimposing the distribution of the known pressure sources derived from the observed ground inflation and the volcanic earthquake distribution onto the 2D velocity model, the magma transportation path in the crust was imaged. This image suggested that the HVZ plays an important role in magma transportation in the upper crust. Moreover, we estimated that the AT magma reservoir in the 30 ka Aira caldera-forming eruptions has the total volume of 490 km3 DRE and is distributed in a depth range of 4–11 km.
Journal Article
Quality of Internet information related to the Mediterranean diet
by
Kodama, Satoru
,
Shimano, Hitoshi
,
Ibe, Yoko
in
alternative medicine
,
Benchmarks
,
Consumer Health Information - standards
2012
The present study aimed to evaluate the quality of Internet information on the Mediterranean diet and to determine the relationship between the quality of information and the website source.
Website sources were categorized as institutional, pharmaceutical, non-pharmaceutical commercial, charitable, support and alternative medicine. Content quality was evaluated using the DISCERN rating instrument, the Health On the Net Foundation's (HON) code principles, and Journal of the American Medical Association (JAMA) benchmarks. Readability was graded by the Flesch Reading Ease score and Flesch-Kincaid Grade Level score.
The phrase 'Mediterranean diet' was entered as a search term into the six most commonly used English-language search engines.
The first thirty websites forthcoming by each engine were examined.
Of the 180 websites identified, thirty-two met our inclusion criteria. Distribution of the website sources was: institutional, n 8 (25 %); non-pharmaceutical commercial, n 12 (38 %); and support, n 12 (38 %). As evaluated by the DISCERN, thirty-one of the thirty-two websites were rated as fair to very poor. Non-pharmaceutical commercial sites scored significantly lower than institutional and support sites (P = 0.002). The mean Flesch Reading Ease score and mean Flesch-Kincaid Grade Level were 55.9 (fairly difficult) and 7.2, respectively. The Flesch-Kincaid Grade Level score determines the difficulty of material by measuring the length of words and sentences and converting the results into a grade level ranging from 0 to 12 (US grade level).
Due to the poor quality of website information on the Mediterranean diet, patients or consumers who are interested in the Mediterranean diet should get advice from physicians or dietitians.
Journal Article