Search

Your search keyword '"Koseki, Junichi"' showing total 729 results
Start Over Author "Koseki, Junichi"
729 results on '"Koseki, Junichi"'

129. Modeling the stress-strain relations of sand in cyclic plane strain loading

Author

Tatsuoka, Fumio, Masuda, Toru, Siddiquee, M.S.A., and Koseki, Junichi

Subjects
Sand -- Analysis, Measuring instruments -- Usage, Earth sciences, Engineering and manufacturing industries, Science and technology
Abstract

A modeling procedure to simulate stress-strain relations of sand subjected to cyclic loading is proposed. Results from drained plane strain compression, extension, and cyclic loading tests on Toyoura sand are analyzed. The monotonic loading behavior is simulated by the generalized hyperbolic equation to use as the skeleton curves in the simulation of cyclic behavior. To construct hysteretic stress-strain curves based on the skeleton curves, the Masing's role is generalized to the proportional rule consisting of the internal and external rules. The drag role is then introduced to simulate cyclic stress-strain behavior in which the stress amplitude increases at a decreasing rate during cyclic loading with a constant strain amplitude. It is assumed that any plastic shear strain increment taking place in a certain direction drags the whole skeleton curve for loading in the opposite direction towards the direction of the concerned shear strain increment. The measured cyclic stress-strain behavior is well simulated by the proposed method. CE Database subject headings: Constitutive models; Cyclic loads; Curvature; Compression tests; Stress-strain relations.

Published
2003

150. Glucuronides of phytoestrogen flavonoid enhance macrophage function via conversion to aglycones by β‐glucuronidase in macrophages

Author

Kaneko, Atsushi, Matsumoto, Takashi, Matsubara, Yosuke, Sekiguchi, Kyoji, Koseki, Junichi, Yakabe, Ryo, Aoki, Katsuyuki, Aiba, Setsuya, and Yamasaki, Kenshi

Subjects
Flavonoids, Mice, Mice, Inbred ICR, Staphylococcus aureus, Glucuronides, β‐glucuronidase, Macrophages, Animals, Staphylococcal Skin Infections, Phytoestrogens, Original Research, estrogen receptor, Glucuronidase
Abstract

Introduction Flavonoids are converted to inactive metabolites like glucuronides in the gut, and circulate mainly as glucuronides in blood stream, resulting in low concentrations of active aglycones in plasma. It is therefore unclear how oral flavonoids exert their effects in tissues. We recently reported the plasma pharmacokinetics of some flavonoids and suggested the possibility that the absorbed flavonoids modified macrophage functions leading to enhance bacterial clearance. We aimed to confirm their pharmacological profiles focusing on tissue macrophages. Methods Pseudoinfection was induced by intradermal injection of FITC‐conjugated and killed Staphylococcus aureus into the ears of mice treated with or without genistein 7‐O‐glucuronide (GEN7G, 1 mg/kg, i.v.). FACS analysis was performed on single cell suspensions dispersed enzymatically from the skin lesions at 6 h post pseudoinfection to evaluate phagocytic activities of monocytes/macrophages (CD11b+Ly6G−) and neutrophils (CD11b+Ly6G+). Phagocytosis of the FITC‐conjugated bacteria by four glucuronides including GEN7G was evaluated in cultures of mouse macrophages. Results After GEN7G injection, genistein was identified in the inflamed ears as well as GEN7G, and the phagocytic activity of CD11b+Ly6G− cells was increased. GEN7G was converted to genistein by incubation with macrophage‐related β‐glucuronidase. Macrophage culture assays revealed that GEN7G increased phagocytosis, and the action was dampened by a β‐glucuronidase inhibitor. Binding of aglycones to estrogen receptors (ERs), putative receptors of flavonoid aglycones, correlated to biological activities, and glucuronidation reduced the binding to ERs. An ER antagonist suppressed the increase of macrophage function by GEN7G, whereas estradiol enhanced phagocytosis as well. Conclusions This study suggests a molecular mechanism by which oral flavonoids are carried as glucuronides and activated to aglycones by β‐glucuronidase in tissue macrophages, and contributes to the pharmacological study of glucuronides.

Published
2017

Catalog

Books, media, physical & digital resources
See catalog results