Publications by authors named "Hirohito Ishikawa"

Excessive immune response and inflammation are associated with an increased risk of various diseases. In particular, excessive myeloperoxidase (MPO) activity in neutrophils causes inflammatory reactions and lifestyle-related diseases. Adlay has a long history of being used as a traditional Chinese medicine.

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1-Kestose (kestose) is the smallest fructooligosaccharide component and shows a particularly high prebiotic function. Both kestose and the bile acid metabolite isoallolithocholic acid (isoalloLCA) are known to be beneficial for human health, especially in terms of immune homeostasis in the gastrointestinal system; however, the effect of kestose on the levels of microbial isoalloLCA producers remains to be clarified. IsoalloLCA is known to be produced by several members of the phylum Bacteroidota that carry the 5α-reductase (5AR) gene, a key isoalloLCA biosynthetic gene.

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Insulin resistance leads to the onset of medical conditions such as type 2 diabetes, and its development is associated with the alteration in the gut microbiota. Although it has been demonstrated that supplementation with prebiotics modulates the gut microbiota, limited evidence is available for effects of prebiotics on insulin resistance, especially for humans. We investigated the prebiotic effect of 1-kestose supplementation on fasting insulin concentration in obesity-prone humans and rats.

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High blood glucose is associated with increased risk of various diseases. Red clover (RC; Trifolium pratense L.) is an edible legume whose sprout is rich in isoflavones such as formononetin and biochanin A.

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Scope: Manuka honey, which shows strong nonperoxide-dependent antibacterial activity, contains unique components, such as methyl syringate 4-O-β-D-gentiobioside (leptosperin) and its aglycone, methyl syringate (MSYR). To determine the potential for biological activity evoked by the ingestion of leptosperin and MSYR, we investigated the absorption and metabolism of these components in manuka honey.

Methods And Results: The incubation of MSYR with liver microsomes or S9 fractions in vitro resulted in the formation of MSYR-glucuronide (MSYR-GA), MSYR-sulfate (MSYR-S), and syringic acid as metabolites.

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Syringic acid is one of the key skeletal structures of plant-derived chemicals. The derivatives of syringic acid have certain biological functions. In this study, a monoclonal antibody to syringic acid-based phytochemicals was prepared and characterized.

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The envelope glycoprotein (Env) of human immunodeficiency virus type I (HIV-1) mediates membrane fusion. To analyze the mechanism of HIV-1 Env-mediated membrane fusion, it is desirable to determine the expression level of Env on the cell surface. However, the quantification of Env by immunological staining is often hampered by the diversity of HIV-1 Env and limited availability of universal antibodies that recognize different Envs with equal efficiency.

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Split reporter proteins capable of self-association and reactivation have applications in biomedical research, but designing these proteins, especially the selection of appropriate split points, has been somewhat arbitrary. We describe a new methodology to facilitate generating split proteins using split GFP as a self-association module. We first inserted the entire GFP module at one of several candidate split points in the protein of interest, and chose clones that retained the GFP signal and high activity relative to the original protein.

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DNA with single-nucleotide (1-nt) gaps can arise during various DNA processing events. These lesions are repaired by X-family DNA polymerases (PolXs) with high gap-filling activity. Some PolXs can bind productively to dNTPs in the absence of DNA and fill these 1-nt gaps.

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Endonuclease IV (EndoIV) is an endonuclease that acts at apurinic/apyrimidinic (AP) sites and is classified as either long-type or short-type. The crystal structures of representative types of EndoIV from Geobacillus kaustophilus and Thermus thermophilus HB8 were determined using X-ray crystallography. G.

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Deoxyribonucleoside triphosphate (dNTP) triphosphohydrolase (dNTPase) from Thermus thermophilus HB8 (TTHB8) hydrolyzes wide variety of dNTPs to deoxyribonucleoside and inorganic triphosphate in magnesium-dependent manner. In this paper, we assess the specificity for various metal ions and of the dNTP triphosphohydrolase activity of the dNTPase from TTHB8. Manganese and cobalt ions more effectively induced the activity for dNTPs than magnesium and, unexpectedly, brought about the degradation of single kind of dNTP.

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In bacterial RNA metabolism, mRNA degradation is an important process for gene expression. Recently, a novel ribonuclease (RNase), belonging to the beta-CASP family within the metallo-beta-lactamase superfamily, was identified as a functional homologue of RNase E, a major component for mRNA degradation in Escherichia coli. Here, we have determined the crystal structure of TTHA0252 from Thermus thermophilus HB8, which represents the first report of the tertiary structure of a beta-CASP family protein.

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