Publications by authors named "Yui Koga"

Background: Severe protein C (PC) deficiency is a rare heritable thrombophilia leading to thromboembolic events during the neonatal period. It remains unclear how individuals with complete PC gene (PROC) defects develop or escape neonatal stroke or purpura fulminans (PF).

Procedure: We studied the onset of disease and the genotype of 22 PC-deficient patients with double mutations in PROC based on our cohort (n = 12) and the previous reports (n = 10) in Japan.

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Background: Neuraminidase (NA) is an essential surface protein for influenza virus replication. NA inhibitors are commonly used for the treatment of influenza patients in Japan. Several mutations that reduce the effect of NA inhibitors have been reported.

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Background: The early diagnosis of inherited thrombophilia in children is challenging because of the rarity and hemostatic maturation.

Methods: We explored protein C (PC), protein S (PS), and antithrombin (AT) deficiencies in 306 thromboembolic patients aged ≤20 y using the screening of plasma activity and genetic analysis.

Results: Reduced activities were determined in 122 patients (40%).

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Background: Influenza virus has neuraminidase (NA), a surface protein with enzymatic activity that is essential for virus replication. Mutation may affect the effectiveness of NA inhibitors that are used for the treatment of influenza patients. In this study, we determined the NA gene sequences from the clinical isolates of influenza patients to examine the chronological genetic changes and the relation to drug susceptibility.

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A 12-year-old Japanese girl developed infective endocarditis and central nervous system disease. The previously healthy girl showed altered consciousness and abnormal behaviors along with the classical signs of septic emboli. Staphylococcus aureus was isolated from peripheral blood, but not, the pleocytotic cerebrospinal fluid.

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The clearance of tissue debris by microglia is a crucial component of maintaining brain homeostasis. Microglia continuously survey the brain parenchyma and utilize extracellular nucleotides to trigger the initiation of their dynamic responses. Extracellular uridine diphosphate (UDP), which leaks or is released from damaged neurons, has been reported to stimulate the phagocytotic activity of microglia through P2Y(6) receptor activation.

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Microglia are major immunocompetent cells in the central nervous system and retain highly dynamic motility. The processes which allow these cells to move, such as chemotaxis and phagocytosis, are considered part of their functions and are closely related to purinergic signaling. Previously, we reported that the activation of the P2Y(6) receptor by UDP stimulation in microglia evoked dynamic cell motility which enhanced their phagocytic capacity, as reported by Koizumi et al.

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Microglia are implicated as a source of diverse proinflammatory factors in the CNS. Extracellular nucleotides are well known to be potent activators of glial cells and trigger the release of cytokines from microglia through purinergic receptors. However, little is known about the role of purinoceptors in microglial chemokine release.

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