Publications by authors named "Kazumi Yagasaki"

Diabetes is caused by abnormal glucose metabolism, and muscle, the largest tissue in the human body, is largely involved. Urolithin A (UroA) is a major intestinal and microbial metabolite of ellagic acid and ellagitannins and is found in fruits such as strawberry and pomegranate. In this present study, we investigated the antidiabetic effects of UroA in L6 myotubes and in KK-A/Ta, a mouse model of type 2 diabetes (T2D).

View Article and Find Full Text PDF

There are three main types of diabetes, namely, type 1 diabetes, type 2 diabetes (T2D), and diabetes in pregnancy (gestational diabetes) [...

View Article and Find Full Text PDF

In the pursuit of bioactive phytochemicals as a therapeutic strategy to manage metabolic risk factors for type 2 diabetes (T2D), aspalathin, -glucosyl dihydrochalcone from rooibos (), has received much attention, along with its -glucosyl flavone derivatives and phlorizin, the apple -glucosyl dihydrochalcone well-known for its antidiabetic properties. We provided context for dietary exposure by highlighting dietary sources, compound stability during processing, bioavailability and microbial biotransformation. The review covered the role of these compounds in attenuating insulin resistance and enhancing glucose metabolism, alleviating gut dysbiosis and associated oxidative stress and inflammation, and hyperuricemia associated with T2D, focusing largely on the literature of the past 5 years.

View Article and Find Full Text PDF

Muscle is the largest tissue in our body and plays an important role in glucose homeostasis and hence diabetes. In the present study, we examined the effects of taxifolin (TXF) on glucose metabolism in cultured L6 muscle cells (myotubes) and in type 2 diabetic (T2D) model KK-A/Ta mice. TXF dose-dependently increased glucose uptake (GU) in L6 myotubes under the condition of insulin absence.

View Article and Find Full Text PDF

Hyperuricemia, the high uric acid (UA) state in blood, has been accepted as an important risk factor for gout. The liver is a main factory of UA production. In the present study, we have examined the effects of three kinds of flavonol and flavones as typical aglycons, i.

View Article and Find Full Text PDF

Hyperuricemia is defined as a disease with high uric acid (UA) levels in the blood and a strong risk factor for gout. Urolithin A (UroA) is a main microbial metabolite derived from ellagic acid (EA), which occurs in strawberries and pomegranates. In this study, we evaluated antihyperuricemic effect of UroA in both cultured hepatocytes and hyperuricemic model mice.

View Article and Find Full Text PDF

Dengue virus (DENV) is the causative agent of dengue fever (DF), dengue haemorrhagic fever (DHF), and dengue shock syndrome (DSS) and continues to be a public health problem in the tropical and subtropical areas. However, there is currently no antiviral treatment for DENV infection. In this study, our aim was to develop a stable reporter replicon cell system that supports constant viral RNA replication in cultured cells.

View Article and Find Full Text PDF

Hyperuricemia is an important risk factor for gout. Isorhamnetin (3'-O-methylquercetin) is an O-methylated flavonol, which occurs in onion, almond and sea buckthorn. It is also one of the metabolites of quercetin in mammals.

View Article and Find Full Text PDF

Urolithin A, a gut microbial metabolite of ellagic acid, is reported to exert anti-inflammatory effects in vitro and in vivo. However, complete mechanisms underlying the regulation of inflammatory responses by urolithin A remain unclear. This study aimed to evaluate the anti-inflammatory potential of urolithin A and its underlying mechanisms in lipopolysaccharide (LPS)-stimulated RAW264 macrophages.

View Article and Find Full Text PDF

Objective: Hyperuricemia is recognized as a main cause of gout. Accumulating clinical evidence suggests that hyperuricemia is strongly associated with insulin resistance and abnormal glucose metabolism. However, there seem no proper animal models for investigating such associations.

View Article and Find Full Text PDF

Hyperuricemia is recognized as an important risk factor for gout. High dietary intake of purine-rich foods such as meats and sea foods increases uric acid (UA) levels in the blood. Taxifolin present in Siberian larch and strawberries has been reported to possess health promoting activities including anti-oxidant effect.

View Article and Find Full Text PDF

Hyperuricemia is characterized by the high uric acid (UA) level in serum (or plasma) and has been considered to be an important risk factor for gout. In the present study, we have attempted to construct an assay system for UA production in vitro employing cultured AML12 hepatocytes. UA levels in balanced salt solution (BSS) in the presence of UA precursor nucleosides, adenosine, inosine, guanosine and xanthine, at 12.

View Article and Find Full Text PDF

Risk factors of type 2 diabetes mellitus (T2D) and cardiovascular disease (CVD) cluster together and are termed the metabolic syndrome. Key factors driving the metabolic syndrome are inflammation, oxidative stress, insulin resistance (IR), and obesity. IR is defined as the impairment of insulin to achieve its physiological effects, resulting in glucose and lipid metabolic dysfunction in tissues such as muscle, fat, kidney, liver, and pancreatic β-cells.

View Article and Find Full Text PDF

In late August 2014, dengue cases were reported in Japan, and a total of 162 cases were confirmed. In the present study, the envelope (E) gene sequences of 12 specimens from the dengue patients were determined. A dengue virus serotype 1 (DENV1) strain (D1/Hu/Shizuoka/NIID181/2014), which was clearly different from the first reported strain (D1/Hu/Saitama/NIID100/2014), was identified, although the other 11 specimens showed the same nucleotide sequences as D1/Hu/Saitama/NIID100/2014.

View Article and Find Full Text PDF
Article Synopsis
  • Autochthonous cases of dengue virus type 1 (DENV-1) were identified in Japan after a 70-year absence of outbreaks, with 11 out of 12 strains sharing identical E gene sequences.
  • Researchers sequenced the entire genomes of 6 DENV-1 strains from a 2014 outbreak, finding significant differences in amino acid residues and genomic sequences among strains.
  • Phylogenetic analysis indicated that one strain likely originated from an infected patient who had traveled to Malaysia, suggesting the infection was imported rather than locally acquired.
View Article and Find Full Text PDF

Enterolactone (ENL) is formed by the conversion of dietary precursors like strawberry lignans via the gut microbiota. Urinary concentrations of lignan metabolites are reported to be significantly associated with a lower risk of Type 2 diabetes (T2D). In the present study, antidiabetic effect of ENL and its modes of action were studied in vitro and in vivo employing a rat skeletal muscle-derived cell line, L6 myocytes in culture, and T2D model db/db mice.

View Article and Find Full Text PDF

The characteristics of genotype V Japanese encephalitis virus (GV JEV) remain poorly understood as only two strains have been isolated to date. In this study, we examined the effects of the GV JEV Muar strain on in vitro growth and pathogenicity in mice; we also evaluated the efficacy of inactivated JEV vaccines against the Muar strain. Although growth of the Muar strain in mouse neuroblastoma N18 cells was clearly worse than that of the GIII Beijing-1 and GI Mie/41/2002 strains, neuroinvasiveness of the Muar strain was similar to that of the Beijing-1 strain and significantly higher than that of the Mie/41/2002 strain.

View Article and Find Full Text PDF

Previous studies have demonstrated antidiabetic effects for rooibos (Aspalathus linearis) and aspalathin (ASP), one of its main polyphenols. Rooibos, an endemic plant of South Africa, is well-known for its use as herbal tea. Green ('unfermented') rooibos has been shown to contain more ASP than 'fermented' rooibos tea, currently the major product.

View Article and Find Full Text PDF

We detected two viruses, Japanese encephalitis virus (JEV)/Kochi/01/2005 and Getah virus (GETV)/Kochi/01/2005 in the same culture supernatant obtained by inoculation of Vero cells with a swine serum sample and subsequent passaging of the supernatant in Vero cells. Phylogenetic analysis using the nucleotide sequences of the complete genome and the E2 region of GETV indicated that GETV/Kochi/01/2005 is most similar to a Mongolian strain. In contrast, a partial sequence of the nsP1 protein coding region of GETV/Kochi/01/2005 showed that it was similar to Japanese strains isolated in the 1980s.

View Article and Find Full Text PDF

Pterostilbene, a methoxylated analogue of resveratrol, is a natural compound primarily found in blueberries and several types of grapes. However, little is known about the effect of pterostilbene on the proliferation of hepatoma cells and its modes of actions. This study was undertaken to characterize its ability to suppress the proliferation of hepatoma AH109A cells and the possible mechanism(s) involved.

View Article and Find Full Text PDF

There have been studies on health beneficial effects of ginger and its components. However, there still remain certain aspects that are not well defined in their anti-hyperglycemic effects. Our aims were to find evidence of possible mechanisms for antidiabetic action of [6]-gingerol, a pungent component of ginger, employing a rat skeletal muscle-derived cell line, a rat-derived pancreatic β-cell line, and type 2 diabetic model animals.

View Article and Find Full Text PDF

Many active components derived from edible natural resources such as plant extracts have recently attracted attention for their potential use as functional foods or drugs for preventing and treating metabolic diseases such as diabetes. To obtain a novel modulator of glucose metabolism, we conducted screening of a small compound library in cultured L6 myotubes. We identified nepodin that stimulated glucose uptake dose-dependently in differentiated L6 myotubes.

View Article and Find Full Text PDF

Daidzein shows estrogenic, antioxidant and antiandrogenic properties as well as cell cycle regulatory activity. However, the antihyperglycemic effect of daidzein remains to be elucidated. In this study, we investigated the in vitro effect of daidzein on glucose uptake, AMPK phosphorylation and GLUT4 translocation on plasma membrane in L6 myotubes and its in vivo antihyperglycmic effect in obese-diabetic model db/db mice.

View Article and Find Full Text PDF

Scope: Molecular mechanisms for the potential antihyperglycemic effect of equol remain to be elucidated. In this study, we investigated the in vitro effect of equol on glucose uptake, AMP-activated protein kinase (AMPK) phosphorylation, and glucose transporter 4 (GLUT4) translocation to plasma membrane in L6 myocytes, and its in vivo antihyperglycemic effect in obese-diabetic model ob/ob mice.

Methods And Results: Equol was found to promote glucose uptake, AMPK phosphorylation, and GLUT4 translocation detected by Western blotting analyses in L6 myotubes under a condition of insulin absence.

View Article and Find Full Text PDF

The effect of natural IgG antibody recognizing β-galactosyl epitope on hepatoma cell invasion was investigated. Anti-β-galactosyl antibody dose-dependently suppressed hepatoma invasion underneath primarily cultured mesothelial cells monolayer without affecting the proliferation, to the same extent as natural IgG antibody with anti-α-galactosyl specificity, which had already been reported to have an anti-metastatic activity. The inhibitory effect of anti-β-galactosyl antibody was completely canceled by adding lactose (galactose-β-1, 4-glucose) to the medium, indicating that this antibody recognized some antigens with β-galactosyl epitope.

View Article and Find Full Text PDF