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4,802 results on '"Yamamoto, Tetsuya"'

6. Energy Spectrum Analysis on a Red Blood Cell Model

Author

Yamamoto, Tetsuya and Watanabe, Hiroshi

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

It is important to understand the dynamics of red blood cells (RBCs) in blood flow. This requires the formulation of coarse-grained RBC models that reproduce the hydrodynamic properties of blood accurately. One of the models that successfully reproduce the rheology and morphology of blood has been proposed by Fedosov et al. [D. A. Fedosov, B. Caswell, and G. E. Karniadakis, Comput. Methods Appl. Mech. Eng., Vol. 199, 1937-1948 (2010)]. The proposed RBC model contains several parameters whose values are determined either by various experiments or physical requirements. In this study, we developed a new method of determining the parameter values precisely from the fluctuations of the RBC membrane. Specifically, we studied the relationship between the spectra of the fluctuations and model parameters. Characteristic peaks were observed in the spectra, whose peak frequencies were dependent on the parameter values. In addition, we investigated the spectra of the radius of gyration. We identified the peaks originating from the spring potential and the volume-conserving potential appearing in the spectra. These results lead to the precise experimental determination of the parameters used in the RBC model., Comment: 26 pages, 13 figures. New results are added

Published
2023

11. Cytotoxic effects of the cigarette smoke extract of heated tobacco products on human oral squamous cell carcinoma: the role of reactive oxygen species and CaMKK2

Author

Kagemichi, Nagao, Umemura, Masanari, Ishikawa, Soichiro, Iida, Yu, Takayasu, Shota, Nagasako, Akane, Nakakaji, Rina, Akimoto, Taisuke, Ohtake, Makoto, Horinouchi, Takahiro, Yamamoto, Tetsuya, and Ishikawa, Yoshihiro

Subjects
Philip Morris International Inc., British American Tobacco PLC, Tobacco industry -- Health aspects, Acetylcysteine -- Health aspects, Smoking -- Health aspects, Squamous cell carcinoma -- Health aspects, Protein kinases -- Health aspects, Psychology and mental health
Abstract

Background The increasing prevalence of heated tobacco products (HTPs) has heightened concerns regarding their potential health risks. Previous studies have demonstrated the toxicity of cigarette smoke extract (CSE) from traditional tobacco's mainstream smoke, even after the removal of nicotine and tar. Our study aimed to investigate the cytotoxicity of CSE derived from HTPs and traditional tobacco, with a particular focus on the role of reactive oxygen species (ROS) and intracellular Ca.sup.2+. Methods A human oral squamous cell carcinoma (OSCC) cell line, HSC-3 was utilized. To prepare CSE, aerosols from HTPs (IQOS) and traditional tobacco products (1R6F reference cigarette) were collected into cell culture media. A cell viability assay, apoptosis assay, western blotting, and Fluo-4 assay were conducted. Changes in ROS levels were measured using electron spin resonance spectroscopy and the high-sensitivity 2ʹ,7ʹ-dichlorofluorescein diacetate assay. We performed a knockdown of calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) by shRNA lentivirus in OSCC cells. Results CSE from both HTPs and traditional tobacco exhibited cytotoxic effects in OSCC cells. Exposure to CSE from both sources led to an increase in intracellular Ca.sup.2+ concentration and induced p38 phosphorylation. Additionally, these extracts prompted cell apoptosis and heightened ROS levels. N-acetylcysteine (NAC) mitigated the cytotoxic effects and p38 phosphorylation. Furthermore, the knockdown of CaMKK2 in HSC-3 cells reduced cytotoxicity, ROS production, and p38 phosphorylation in response to CSE. Conclusion Our findings suggest that the CSE from both HTPs and traditional tobacco induce cytotoxicity. This toxicity is mediated by ROS, which are regulated through Ca.sup.2+ signaling and CaMKK2 pathways. Graphical Abstract Keywords: Heated tobacco products (HTPs), Calcium, Oral cancer, Calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2), Reactive oxygen species (ROS), Author(s): Nagao Kagemichi[sup.1,2], Masanari Umemura[sup.1], Soichiro Ishikawa[sup.1,3], Yu Iida[sup.1,2], Shota Takayasu[sup.1], Akane Nagasako[sup.1], Rina Nakakaji[sup.1,3], Taisuke Akimoto[sup.2], Makoto Ohtake[sup.2], Takahiro Horinouchi[sup.4], Tetsuya Yamamoto[sup.2] and Yoshihiro Ishikawa[sup.1] Background Tobacco is responsible [...]

Published
2024
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25. Causes and consequences of stress generation: Longitudinal associations of negative events, aggressive behaviors, rumination, and depressive symptoms

Author

Hasegawa, Akira, Oura, Shin-ichi, Yamamoto, Tetsuya, Kunisato, Yoshihiko, Matsuda, Yuko, and Adachi, Masaki

Subjects
Aggressiveness (Psychology) -- Health aspects, Depression, Mental -- Risk factors, Rumination (Psychology) -- Health aspects, Stress (Psychology) -- Causes of -- Complications and side effects, Psychology and mental health
Abstract

The present study examined the causes and consequences of stress generation in university students in Japan. A two-wave longitudinal study with an 8- or 9-week interval was conducted in the fall of 2020. Undergraduate and graduate students at four universities in Japan (N = 201) completed self-report measures assessing experiences of negative interpersonal dependent events, negative non-interpersonal events, and negative independent events at two times. At the same time, they also responded to measures of aggressive behaviors, trait rumination, and depressive symptoms. Path analyses revealed that baseline aggressive behaviors were positively associated with an increase in subsequent negative interpersonal dependent events, even after controlling for the influences of negative interpersonal dependent events, rumination, and depressive symptoms at baseline. However, aggressive behaviors were not significantly associated with subsequent negative non-interpersonal dependent events or negative independent events. These findings suggest that aggressive behaviors may have been a factor leading to interpersonal stress generation. Furthermore, all categories of negative event experiences predicted an increase in subsequent depressive symptoms, but not subsequent rumination, and rumination was not significantly associated with subsequent depressive symptoms. This research extends previous studies on the causes and consequences of stress generation conducted in the US by using specific measures of aggressive behaviors and including a non-restricted sample of university students in Japan., Author(s): Akira Hasegawa [sup.1] , Shin-ichi Oura [sup.1] , Tetsuya Yamamoto [sup.2] , Yoshihiko Kunisato [sup.3] , Yuko Matsuda [sup.4] , Masaki Adachi [sup.4] Author Affiliations: (1) grid.420117.1, 0000 0000 [...]

Published
2023
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35. Prediction of the debulking effect of rotational atherectomy using optical frequency domain imaging: a prospective study

Author

Hamana, Tomoyo, Kawamori, Hiroyuki, Toba, Takayoshi, Nishimori, Makoto, Tanimura, Kosuke, Kakizaki, Shunsuke, Nakamura, Koichi, Fujimoto, Daichi, Sasaki, Satoru, Osumi, Yuto, Fujii, Masayoshi, Iwane, Seigo, Yamamoto, Tetsuya, Naniwa, Shota, Sakamoto, Yuki, Fukuishi, Yuta, Matsuhama, Koshi, Hirata, Ken-ichi, and Otake, Hiromasa

Published
2023
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46. Clinical impact of optical coherence tomography findings after drug-coated balloon treatment for patients with acute coronary syndromes

Author

Yamamoto, Tetsuya, Kawamori, Hiroyuki, Toba, Takayoshi, Kakizaki, Shunsuke, Nakamura, Koichi, Fujimoto, Daichi, Sasaki, Satoru, Fujii, Hiroyuki, Hamana, Tomoyo, Osumi, Yuto, Iwane, Seigo, Naniwa, Shota, Sakamoto, Yuki, Matsuhama, Koshi, Fukuishi, Yuta, Kozuki, Amane, Shite, Junya, Iwasaki, Masamichi, Ishida, Akihiko, Hirata, Ken-ichi, and Otake, Hiromasa

Published
2023
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49. Encoding of self-initiated actions in axon terminals of the mesocortical pathway

Author

Ohtake, Makoto, primary, Abe, Kenta, additional, Hasegawa, Masashi, additional, Itokazu, Takahide, additional, Selvakumar, Vihashini, additional, Matunis, Ashley, additional, Stacy, Emma, additional, Froebrich, Emily, additional, Huynh, Nathan, additional, Lee, Haesuk, additional, Kambe, Yuki, additional, Yamamoto, Tetsuya, additional, Sato, Tatsuo K., additional, and Sato, Takashi R., additional

Published
2024
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