Publications by authors named "Kenji Hirayama"

Background: Mother-to-child transmission (MTCT) of Trypanosoma cruzi and hepatitis B virus (HBV) increases morbidity and disability in Latin America and the Caribbean. The tailormade comprehensive antenatal care based on the Framework for the elimination of MTCT of HIV, syphilis, hepatitis B virus (HBV), and Chagas disease (EMTCT Plus) has been implemented in the region since 2018 through a private-public partnership. This study aimed to estimate the effectiveness of the intervention in preparing MTCT of T.

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Liver injury with marked elevation of aspartate aminotransferase enzyme (AST) is commonly observed in dengue infection. To understand the pathogenesis of this liver damage, we compared the plasma levels of hepatic specific, centrilobular predominant enzymes (glutamate dehydrogenase, GLDH; glutathione S transferase-α, αGST), periportal enriched 4-hydroxyphenylpyruvate dioxygenase (HPPD), periportal predominant arginase-1 (ARG-1), and other non-specific biomarkers (paraoxonase-1, PON-1) in patients with different outcomes of dengue infection. This hospital-based study enrolled 87 adult dengue patients, stratified into three groups based on plasma AST levels (< 80, 80-400, > 400 U/L) in a 1:1:1 ratio (n = 40, n = 40, n = 40, respectively.

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Artemisinin (ART) combination therapy is the main treatment for malaria. Pfk13 mutations (or K13 mutations, Kelch 13) are associated with ART resistance. This study aims to conduct a systematic review and meta-analysis of the prevalence of K13 mutations with ART resistance in malaria-endemic countries.

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Background: Although the Philippines targets malaria elimination by 2030, it remains to be a disease that causes considerable morbidity in provinces that report malaria. Pregnant women residing in endemic areas are a vulnerable population, because in addition to the risk of developing severe malaria, their pregnancy is not followed through, and the outcome of their pregnancy is unknown. This study determined the utility of real-world data integrated with disease surveillance data set as real-world evidence of pregnancy and delivery outcomes in areas endemic for malaria in the Philippines.

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Background: Benzothiazole derivatives have been reported to possess a wide range of biological activities, including antimalarial activity. This systematic review aims to summarize and evaluate the antimalarial activities of benzothiazole analogs.

Methods: We conducted an electronic search using nine databases in October 2017 and subsequently updated in September 2022.

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Community-led total sanitation (CLTS) is a widely used approach for enhancing sanitation practices. However, the impact of boosted CLTS on household latrine ownership has not been adequately evaluated. This study aims to investigate the factors associated with latrine possession among households, with a specific focus on single and CLTS-boosting implementation.

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Article Synopsis
  • * Researchers used mRNA-containing lipid nanoparticles (mRNA-LNPs) to successfully generate antigen-specific cytotoxic T lymphocytes in mice.
  • * The results indicate that mRNA-LNPs can create protective memory T cells against malaria, suggesting potential for future vaccine development.
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Article Synopsis
  • Japan likely has around 3,000 cases of Chagas disease, but lacks data and policies for prevention and care, prompting this study to investigate the situation among Latin American migrants.
  • Researchers analyzed 428 Latin American participants, finding a higher-than-expected prevalence of Chagas disease at 1.6%, particularly among Bolivians at 5.3%, and identified factors influencing the likelihood of being infected and barriers to accessing Japan's healthcare system.
  • The study suggests that screening asymptomatic individuals at risk could be a cost-effective approach in Japan, but implementation must address the specific challenges faced by Latin American migrants in accessing healthcare.
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Background: Current therapeutic agents, including nifurtimox and benznidazole, are not sufficiently effective in the chronic phase of Trypanosoma cruzi infection and are accompanied by various side effects. In this study, 120 kinds of extracts from medicinal herbs used for Kampo formulations and 94 kinds of compounds isolated from medicinal herbs for Kampo formulations were screened for anti-T. cruzi activity in vitro and in vivo.

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We report the structural functionalization of the terminal amino group of N -(7-chloroquinolin-4-yl) butane-1,4-diamine, leading to a series of 7-chloro-4-aminoquinoline derivatives, and their evaluation as potent anti-malarial and anti-viral agents. Some compounds exhibited promising anti-malarial effects against the Plasmodium falciparum 3D7 (chloroquine-sensitive) and Dd2 (chloroquine-resistant) strains. In addition, these compounds were assayed in vitro against influenza A virus (IAV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

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Background: The severity of dengue infection has been reportedly associated with patients' allergic reactions. To further elucidate the role of allergy in dengue severity, we conducted a matched case-control study to assess the association between allergic background and dengue shock syndrome.

Methods: This is a matched case-control study that was carried out in the Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam from January to December 2017.

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Dengue is classified as an endemic infectious disease, which is transmitted by Aedes mosquitos. Kinetic studies, which monitor the viral load of the disease, have been the mainstay for several decades in humanity's quest to control this disease. Our study aims to systematically evaluate the usage of different timing systems in dengue kinetic studies.

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The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a serious threat to global public health. The emergence of SARS-CoV-2 variants is a significant concern regarding the continued effectiveness of vaccines and antiviral therapeutics. Thus, natural products such as foods, drinks, and other compounds should be investigated for their potential to treat COVID-19.

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Objectives: This study aimed to evaluate the efficacy and adverse events of favipiravir in patients with COVID-19.

Methods: Our protocol was registered on PROSPERO (CRD42020206305). Fourteen databases were searched until February 8, 2021.

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Although several in vitro assays that predict the sensitizing potential of chemicals have been developed, none can distinguish between chemical respiratory and skin sensitizers. Recently, we established a new three-dimensional dendritic cell (DC) coculture system consisting of a human airway epithelial cell line, immature DCs derived from human peripheral monocytes, and a human lung fibroblast cell line. In this coculture system, compared to skin sensitizers, respiratory sensitizers showed enhanced mRNA expression in DCs of the key costimulatory molecule OX40 ligand (OX40L), which is important for T helper 2 (Th2) cell differentiation.

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The emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic in 2019 has led to a global health crisis. Mutations of the SARS-CoV-2 genome have impeded the development of effective therapeutics and vaccines against SARS-CoV-2. Natural products are important for discovering therapeutics to treat the 2019 coronavirus disease (COVID-19).

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Objective: Vestibular schwannoma is a benign tumor in the schwannoma cells of the 8th cranial nerve. It causes symptoms like tinnitus, vertigo and end up with loss of hearing so the appropriate treatment is very important. There are many treatment techniques including conservative, surgery and radiosurgery.

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Background: Since the COVID-19 pandemic began, there have been concerns related to the preparedness of healthcare workers (HCWs). This study aimed to describe the level of awareness and preparedness of hospital HCWs at the time of the first wave.

Methods: This multinational, multicenter, cross-sectional survey was conducted among hospital HCWs from February to May 2020.

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A chronic helminth infection can alter host immune response and affect malaria infection. We conducted a systematic review and meta-analysis to find the impact of anthelmintic treatment on malaria prevalence, incidence, and parasitemia. Nine and 12 electronic databases were searched on 28 July 2015 and 26 June 2020 for relevant studies.

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Background: Predictive markers represent a solution for the proactive management of severe dengue. Despite the low mortality rate resulting from severe cases, dengue requires constant examination and round-the-clock nursing care due to the unpredictable progression of complications, posing a burden on clinical triage and material resources. Accordingly, identifying markers that allow for predicting disease prognosis from the initial diagnosis is needed.

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Three phenylpropanoid-conjugated iridoid glucosides, acetylgaertneric acid (1), acetyldehydrogaertneroside (2), and dehydrogaertneric acid (10), together with nine known related iridoid glucosides (3-9, 11, and 12), two coumaroyl alkaloids, one benzenoid, and three flavonoid glucosides were isolated from leaves of Morinda morindoides (Rubiaceae). Structures of these isolated compounds were determined using spectroscopic analysis. Compounds 1-18 and previously isolated compounds (19-29) were evaluated for anti-trypanosomal activity against Trypanosoma cruzi Tulahuen strain (trypomastigote and amastigote) together with cytotoxicity against host cells, new-born mouse heart cells.

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