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Your search keyword '"Akase, T."' showing total 4 results
Start Over Author "Akase, T." Publisher govi-verlag pharmazautischer verlag
4 results on '"Akase, T."'

1. Amorphous nanosilica particles induce ROS generation in Langerhans cells.

Author

Yoshida T, Yoshikawa T, Nabeshi H, Matsuyama K, Hirai T, Akase T, Yoshioka Y, Itoh N, and Tsutsumi Y

Subjects
Cell Line, Humans, Langerhans Cells drug effects, Particle Size, Langerhans Cells metabolism, Nanoparticles toxicity, Reactive Oxygen Species metabolism, Silicon Dioxide toxicity
Abstract

Generation of total intracellular reactive oxygen species (ROS) was measured in XS52 cells, a Langerhans cell-like line, treated with different sized amorphous silica particles. The results suggested that exposure to amorphous nanosilica particles (nSPs) with a particle size of 70 nm induced a higher level of ROS generation than did exposure to micron-sized amorphous silica particles. This finding means that it is essential to examine the biological effects of ROS generated after exposure to nSPs, which will provide useful information for hazard identification as well as the design of safer nanomaterials.

Published
2012

2. Dermal absorption of amorphous nanosilica particles after topical exposure for three days.

Author

Hirai T, Yoshikawa T, Nabeshi H, Yoshida T, Akase T, Yoshioka Y, Itoh N, and Tsutsumi Y

Subjects
Administration, Cutaneous, Administration, Topical, Animals, Ear, External metabolism, Mice, Mice, Inbred BALB C, Microscopy, Electron, Transmission, Silicon Dioxide administration & dosage, Suspensions, Nanoparticles administration & dosage, Silicon Dioxide pharmacokinetics, Skin Absorption physiology
Abstract

The skin penetration and cellular localization of well-dispersed amorphous nanosilica particles (nSPs) with a diameter of 70 nm was analyzed in mice. Our results suggest that after topical exposure for three days the particles penetrate the skin barrier and are transported to the lymph nodes. These findings underscore the need to examine biological effects following dermal exposure to nSPs for the development of safer use of nSPs.

Published
2012

3. Size-dependent immune-modulating effect of amorphous nanosilica particles.

Author

Hirai T, Yoshikawa T, Nabeshi H, Yoshida T, Tochigi S, Uji M, Ichihashi K, Akase T, Yamashita T, Yamashita K, Nagano K, Abe Y, Kamada H, Tsunoda S, Yoshioka Y, Itoh N, and Tsutsumi Y

Subjects
Animals, CD8-Positive T-Lymphocytes drug effects, CD8-Positive T-Lymphocytes immunology, Female, Interferon-gamma, Mice, Mice, Inbred C57BL, Ovalbumin immunology, Particle Size, Silicon Dioxide chemistry, Spleen cytology, Spleen immunology, Immunologic Factors, Nanoparticles, Silicon Dioxide pharmacology
Abstract

The immune-modulating effect following intradermal injection of various-sized amorphous silica particles was analyzed in terms of induction of ovalbumin-specific CD8+ T cells in vivo. IFN-gamma ELISPOT assays revealed that only nanosilica particles with a diameter of less than 100 nm significantly enhanced CD8+ T cell responses against ovalbumin. These results indicate that the size of nanomaterials is a critical determinant in terms of their safe use.

Published
2011

4. Size-dependent cytotoxic effects of amorphous silica nanoparticles on Langerhans cells.

Author

Nabeshi H, Yoshikawa T, Matsuyama K, Nakazato Y, Arimori A, Isobe M, Tochigi S, Kondoh S, Hirai T, Akase T, Yamashita T, Yamashita K, Yoshida T, Nagano K, Abe Y, Yoshioka Y, Kamada H, Imazawa T, Itoh N, Tsunoda S, and Tsutsumi Y

Subjects
Animals, Cell Line, Cell Survival drug effects, Keratinocytes drug effects, L-Lactate Dehydrogenase metabolism, Langerhans Cells enzymology, Langerhans Cells ultrastructure, Mice, Microscopy, Electron, Transmission, Particle Size, Thymidine metabolism, Langerhans Cells drug effects, Nanoparticles toxicity, Silicon Dioxide toxicity
Abstract

Amorphous silica nanoparticles (nSPs), are widely used in medicines, cosmetics and food. However, due to their reduced particle size they are suspected to pose new risks induced by changes in biological reactivity and kinetics, which differ from those of bulk materials. In a previous study, we showed that silica particles with a diameter of 70 nm penetrated the stratum corneum (SC) of mouse skin and were taken up by living cells such as keratinocytes and Langerhans cells. To clarify the relationship between particle size, distribution and cellular response, we have evaluated size-dependent intracellular localization and cytotoxicity of silica particles, using the mouse epidermal Langerhans cell line XS52. On treatment with silica particles of diameters 70, 300, and 1000 nm, cellular uptake and cytotoxicity increased with reduction in particle size. These results suggest that smaller sized silica particles induced greater cytotoxicity against Langerhans cells, which was correlated with the quantity of particle uptake into the cells.

Published
2010

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