Publications by authors named "Kazu Okuma"

A multiomic study of the structural characteristics of type A and B influenza viruses by means of highly spectrally resolved Raman spectroscopy is presented. Three virus strains, A H1N1, A H3N2, and B98, were selected because of their known structural variety and because they have co-circulated with variable relative prevalence within the human population since the re-emergence of the H1N1 subtype in 1977. Raman signatures of protein side chains tyrosine, tryptophan, and histidine revealed unequivocal and consistent differences for pH characteristics at the virion surface, while different conformations of two C-S bond configurations in and methionine rotamers provided distinct low-wavenumber fingerprints for different virus lineages/subtypes.

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This study aimed to test the effectiveness of Raman spectroscopy in the characterization of the degrees of physiological stress and virulence in clinical swab samples collected from patients affected by oral candidiasis. Raman experiments were conducted on a series of eight isolates, both in an as-collected state and after biofilm purification followed by 3 days of culture. The outputs were matched to optical microscopy observations and the results of conventional chromogenic medium assays.

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  • STLV-1 is a retrovirus similar to HTLV-1 that causes adult T-cell leukemia and is highly prevalent in Japanese macaques, yet its molecular epidemiology hasn't been fully studied.
  • A study analyzed the complete genome sequences of STLV-1 from 68 JMs across 5 different troops, revealing high genome similarity within troops and low nucleotide diversity overall.
  • The findings suggest that the high homogeneity of STLV-1 genomes in JMs is partly due to the absence of G-to-A hypermutation, which is often seen in HTLV-1 in humans and African primates.
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Ephrin type-A receptor 2 (EPHA2) is a receptor tyrosine kinase that is overexpressed in a variety of cancers, including breast cancer. EPHA2 expression may be causally related to tumorigenesis; therefore, it is important to understand how expression is regulated. We previously reported that EPHA2 antisense RNA (EPHA2-AS), a natural antisense transcript, is an important modulator of EPHA2 mRNA levels and hence production of EPHA2 protein.

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This study investigates the neutralizing activity against the XBB1.5 variant and the ancestral strain in a population post-bivalent vaccination using a pseudo virus assay validated with authentic virus assay. While bivalent booster vaccination and past infections enhanced neutralization against the XBB 1.

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  • The World Health Organization estimates that 5-10 million people are infected with HTLV-1, but this number could be low due to limited data.
  • Reliable data exists for only about 1.5 billion people worldwide, leaving many infections potentially undetected.
  • The study evaluates a new rapid test, Espline HTLV-I/II, which could enhance our ability to quickly and easily identify HTLV-1 infections without needing expensive lab equipment.
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Raman spectroscopy was applied to study the structural differences between herpes simplex virus Type I (HSV-1) and Epstein-Barr virus (EBV). Raman spectra were first collected with statistical validity on clusters of the respective virions and analyzed according to principal component analysis (PCA). Then, average spectra were computed and a machine-learning approach applied to deconvolute them into sub-band components in order to perform comparative analyses.

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The latest RNA genomic mutation of SARS-CoV-2 virus, termed the Omicron variant, has generated a stream of highly contagious and antibody-resistant strains, which in turn led to classifying Omicron as a variant of concern. We systematically collected Raman spectra from six Omicron subvariants available in Japan (i.e.

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  • Stem cell therapy, particularly human adipose-derived stem cells (hASCs), shows potential in regenerative medicine and is easily harvested for applications in plastic surgery, including fat grafting and wound healing.
  • Platelet-rich plasma (PRP), rich in growth factors like PDGF, enhances hASC proliferation, adhesion, and migration by activating key signaling pathways such as AKT and ERK1/2.
  • PRP treatment proves to be more effective than PDGF alone in promoting hASC movement and adhesion, leading to improved cell growth and therapeutic outcomes.
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  • This study investigated how outer-membrane vesicles (OMVs) from oral bacteria influence the degeneration of neuroblastoma cells, specifically using in situ Raman spectroscopy to track metabolomic changes.
  • OMVs are associated with Alzheimer's disease (AD) as they deliver harmful toxins that can damage neurons, but the exact chemical processes involved are not well understood.
  • The research revealed important chemical signatures and mechanisms related to neuronal degradation, including the roles of lipopolysaccharides and proteins involved in forming amyloid plaques and Tau tangles that worsen AD symptoms.
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Hydrolytic reactions taking place at the surface of a silicon nitride (SiN) bioceramic were found to induce instantaneous inactivation of Human herpesvirus 1 (HHV-1, also known as Herpes simplex virus 1 or HSV-1). SiN is a non-oxide ceramic compound with strong antibacterial and antiviral properties that has been proven safe for human cells. HSV-1 is a double-stranded DNA virus that infects a variety of host tissues through a lytic and latent cycle.

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Adult T cell leukemia (ATL) is an aggressive hematologic disease caused by human T cell leukemia virus type 1 (HTLV-1) infection. Various animal models of HTLV-1 infection/ATL have been established to elucidate the pathogenesis of ATL and develop appropriate treatments. For analyses employing murine models, transgenic and immunodeficient mice are used because of the low infectivity of HTLV-1 in mice.

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Immune responses in humanized mice are generally inefficient without co-transplantation of human thymus or HLA transgenes. Previously, we generated humanized mice via the intra-bone marrow injection of CD133+ cord blood cells into irradiated adult immunodeficient mice (IBMI-huNSG mice), which could mount functional immune responses against HTLV-1, although the underlying mechanisms were still unknown. Here, we investigated thymocyte development in IBMI-huNSG mice, focusing on the roles of human and mouse MHC restriction.

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  • A study was conducted to evaluate the effectiveness of convalescent plasma therapy for COVID-19 in high-risk patients who showed symptoms within five days.
  • The trial involved 25 patients, with no significant difference in viral load changes between those receiving convalescent plasma and those receiving standard care over the first five days.
  • The results suggest that early convalescent plasma treatment does not reduce SARS-CoV-2 viral load compared to standard care alone within that timeframe.
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  • A case-control study was conducted to assess COVID-19 infection risk among healthcare workers, collecting data on demographics, contact behaviors, and protective equipment usage.
  • Out of 1,899 participants, 161 (8.5%) were found to be seropositive, with physical contact and aerosol-generating procedures significantly increasing risk.
  • The use of goggles and N95 masks effectively reduced the risk of infection, and seroprevalence was notably higher in outbreak wards compared to COVID-19 dedicated wards.
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  • - A small percentage of people infected with HTLV-1 can develop adult T-cell leukemia/lymphoma, a tough-to-treat disease, due to impaired CTLs, which are essential for fighting off the virus and cancer cells.
  • - Researchers used Japanese monkeys infected with STLV-1 (similar to HTLV-1) to test a therapeutic vaccine made from their own blood cells, which activated their CTLs and showed promising results in boosting immune responses.
  • - Vaccinated monkeys displayed increased STLV-1-specific CTL activity and a reduction in viral load after vaccination, but the immune responses peaked at 3-4 months and required additional boosters to maintain effectiveness over time.
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Human T-cell leukemia virus type 1 (HTLV-1) causes serious and intractable diseases in some carriers after infection. The elimination of infected cells is considered important to prevent this onset, but there are currently no means by which to accomplish this. We previously developed "virotherapy", a therapeutic method that targets and kills HTLV-1-infected cells using a cytolytic recombinant vesicular stomatitis virus (rVSV).

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  • Antibody levels against SARS-CoV-2 decrease over time, but their ability to neutralize the virus improves as the immune response matures.
  • A study of convalescent plasma showed that while total antibody levels declined, the potency of these antibodies against the original virus increased significantly.
  • Late-stage antibodies demonstrated better effectiveness against emerging variants like B.1.351 and P.1, indicating that even as overall antibody levels drop, protection against the virus may still be maintained.
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Background: In order to tackle the COVID-19 pandemic, a COVID-19 convalescent plasma (CCP) procurement program was initiated in Japan in April 2020. The program was a collaboration between a government-managed national hospital, an infectious disease research institute, and a blood banking organization. Each party assumed different responsibilities: recruitment, SARS-CoV-2 antibody profiling, and plasmapheresis; conduction of screening tests; and SARS-CoV-2 blood testing, respectively.

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Introduction: Convalescent plasma transfusion (CPT), a potential therapy for coronavirus disease 2019 (COVID-19), requires strict quality control of the donor blood. Whether to confirm the disappearance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA (RNAemia) in convalescent donor blood or not is unclear. Reports recommending the proof of viral disappearance from the blood are controversial.

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Human T-cell leukemia virus type 2 (HTLV-2) is non-endemic in Japan unlike the related HTLV type 1. Previously, although HTLV-2-seropositivity was identified via western blotting in one male blood donor in Japan, there have been no reports of HTLV-2 provirus detection by nucleic acid testing. In this report, one Japanese pregnant woman was clinically diagnosed as being HTLV-2-infected with a line immunoassay for specific antibodies after primary testing through prenatal screening in Japan.

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Human T cell leukemia virus type 1 (HTLV-1) is mainly transmitted vertically through breast milk. The rate of mother-to-child transmission (MTCT) through formula feeding, although significantly lower than through breastfeeding, is approximately 2.4%-3.

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Background: The reliable diagnosis of human T-cell leukemia virus type 1 (HTLV-1) infection is important, particularly as it can be vertically transmitted by breast feeding mothers to their infants. However, current diagnosis in Japan requires a confirmatory western blot (WB) test after screening/primary testing for HTLV-1 antibodies, but this test often gives indeterminate results. Thus, this collaborative study evaluated the reliability of diagnostic assays for HTLV-1 infection, including a WB-based one, along with line immunoassay (LIA) as an alternative to WB for confirmatory testing.

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Background: Simian T-cell leukemia virus type 1 (STLV-1) is disseminated among various non-human primate species and is closely related to human T-cell leukemia virus type 1 (HTLV-1), the causative agent of adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. Notably, the prevalence of STLV-1 infection in Japanese macaques (JMs) is estimated to be > 60%, much greater than that in other non-human primates; however, the mechanism and mode of STLV-1 transmission remain unknown. The aim of this study is to examine the epidemiological background by which STLV-1 infection is highly prevalent in JMs.

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Patients with adult T-cell leukemia (ATL) exhibit a poor prognosis and overall survival rate when treated with standard chemotherapy, highlighting the continued requirement for the development of novel safe and effective therapies for human T-cell leukemia virus type 1 (HTLV-1)-related diseases. In this study, we demonstrated that MK-2048, a second-generation HIV-1 integrase (IN) inhibitor, potently and selectively kills HTLV-1-infected cells. Differential transcriptome profiling revealed significantly elevated levels of gene expression of the unfolded protein response (UPR) PKR-like ER kinase (PERK) signaling pathway in ATL cell lines following MK-2048 treatment.

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