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Search Results: 1 - 10 of 2055 matches for " Atsushi Inanobe "
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Conformational Changes Underlying Pore Dilation in the Cytoplasmic Domain of Mammalian Inward Rectifier K+ Channels
Atsushi Inanobe, Atsushi Nakagawa, Yoshihisa Kurachi
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079844
Abstract: The cytoplasmic domain of inward rectifier K+ (Kir) channels associates with cytoplasmic ligands and undergoes conformational change to control the gate present in its transmembrane domain. Ligand-operated activation appears to cause dilation of the pore at the cytoplasmic domain. However, it is still unclear how the cytoplasmic domain supports pore dilation and how alterations to this domain affect channel activity. In the present study, we focused on 2 spatially adjacent residues, i.e., Glu236 and Met313, of the G protein-gated Kir channel subunit Kir3.2. In the closed state, these pore-facing residues are present on adjacent βD and βH strands, respectively. We mutated both residues, expressed them with the m2-muscarinic receptor in Xenopus oocytes, and measured the acetylcholine-dependent K+ currents. The dose-response curves of the Glu236 mutants tended to be shifted to the right. In comparison, the slopes of the concentration-dependent curves were reduced and the single-channel properties were altered in the Met313 mutants. The introduction of arginine at position 236 conferred constitutive activity and caused a leftward shift in the conductance-voltage relationship. The crystal structure of the cytoplasmic domain of the mutant showed that the arginine contacts the main chains of the βH and βI strands of the adjacent subunit. Because the βH strand forms a β sheet with the βI and βD strands, the immobilization of the pore-forming β sheet appears to confer unique properties to the mutant. These results suggest that the G protein association triggers pore dilation at the cytoplasmic domain in functional channels, and the pore-constituting structural elements contribute differently to these conformational changes.
Compound-Induced Block of Ion Channel Pore Function: Inward-Rectifier Potassium Channels as a Model
Kazuharu Furutani,Hiroshi Hibino,Atsushi Inanobe,Yoshihisa Kurachi
Molecular and Cellular Pharmacology , 2009,
Abstract: Small chemical compounds modulate ion channel functions. This is the reflection of ligand interactions with ion channels at their various sites. Many biophysical and biochemical researches have been performed on this subject and have provided important basic concepts on the structure-functional relationships of ion channels. Especially, ion channel blockers have been excellent tools for biophysical studies of ion channels and some of them are actually used for treating various diseases. The mechanisms underlying the blocking action of various chemical compounds, however, remain largely unknown at the atomic level, partly because of the promiscuous nature of the reaction. As one of the attempts to overcome the problem, we have adopted a novel approach combining molecular pharmacology and in silico analyses in the study of block of astroglial Kir4.1 channel by various antidepressants, including nortriptyline and fluoxetine. In molecular pharmacology experiments, we have demonstrated that Thr128 and Glu158 of Kir4.1 facing the central cavity play an important role in determining the sensitivities of the Kir channel to the antidepressants. On the other hand, we abstracted common sets of features from Kir4.1 channel blockers by the computer-aided technique that quantitatively correlates their chemical structures with IC50 values for Kir4.1 channel current block. By combining these two lines of studies, we modeled the channel-drug interaction for Kir4.1-block, showing that the compound is accommodated between Thr128 and Glu158 within the central cavity of the channel. This combined approach may be useful to obtain some insights in the structure-function relationship of various ion channels and will shed light on the basic understandings of ion permeation and block.
Economic Growth with Asset Bubbles in a Small Open Economy  [PDF]
Atsushi Motohashi
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.65097
Abstract: This paper analyzes the characteristics of asset bubbles in a small open economy. First, we show that financial globalization relaxes the existence conditions for asset bubbles. This result implies that more countries may experience asset bubbles in a global economy. Second, we show that the effect of asset bubbles in a global economy is larger than in a closed economy. In particular, countries with high financial friction experience a high economic growth rate before a foreign bubble bursts and they are subjected to more negative influence after that. This conclusion implies that financial globalization may cause large economic movements before and after a bubble bursts.
Eating disorders, body image, and dichotomous thinking among Japanese and Russian college women  [PDF]
Atsushi Oshio, Tatiana Meshkova
Health (Health) , 2012, DOI: 10.4236/health.2012.47062
Abstract: This study explored cross-cultural differences between Japan and Russia in terms of women’s body images, proneness to eating disorders, and the effects of dichotomous thinking. Participants included 419 Japanese and 187 Russian college women who completed the Dichotomous Thinking Inventory (DTI), the 26-item version of the Eating Attitudes Test, and responses regarding nine figures representing female body shapes. The mean age of the participants was 19.8 years, with no significant age differences between the countries. The results showed that Japanese women have leaner ideal body images than Russian women, whereas there were no cross-cultural differences in the participants’ real body images. DTI scores among Russian participants were higher than DTI scores among Japanese participants, which indicated that Russian women think more dichotomously than Japanese. Structural equation modeling indicated a significantly negative effect of dichotomous thinking only on real body image in Russia; the ideal body image had greater effects on eating disorder in Russia than in Japan.
Thermal Energy Collection Forecasting Based on Soft Computing Techniques for Solar Heat Energy Utilization System  [PDF]
Atsushi Yona, Tomonobu Senjyu
Smart Grid and Renewable Energy (SGRE) , 2012, DOI: 10.4236/sgre.2012.33030
Abstract: In recent years, introduction of alternative energy sources such as solar energy is expected. Solar heat energy utilization systems are rapidly gaining acceptance as one of the best solutions to be an alternative energy source. However, thermal energy collection is influenced by solar radiation and weather conditions. In order to control a solar heat energy utilization system as accurate as possible, it requires method of solar radiation estimation. This paper proposes the forecast technique of a thermal energy collection of solar heat energy utilization system based on solar radiation forecasting at one-day-ahead 24-hour thermal energy collection by using three different NN models. The proposed technique with application of NN is trained by weather data based on tree-based model, and tested according to forecast day. Since tree-based-model classifies a meteorological data exactly, NN will train a solar radiation with smoothly. The validity of the proposed technique is confirmed by computer simulations by use of actual meteorological data.
Effectiveness of Child Care Policies in an Economy with Child Care Services  [PDF]
Masaya Yasuoka, Atsushi Miyake
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.35085
Abstract: This paper describes how fertility is determined in a model that assumes the existence of child-care services. When child-care services exist, two multiple states result: a state that brings about low fertility with low female labor partici-pation, and a state that brings about high fertility with high female labor participation. This result is consistent with the positive correlation that is found between the total fertility rate and female labor participation in developed countries, as described by Ahn and Mira (2002) [1] and others. Moreover, this paper presents analyses of the effects of child-care policies, for example, a child allowance and a subsidy for child-care services policies. These policies instantaneously raise fertility. However, in a dynamic general equilibrium model, these policies might pull down fertility because capital accumulation decreases in the long run. If income growth continues in the long run, then the child allowance can always pull up fertility. However, if the income level converges to constant level in the long run, then the child allowance might pull down fertility. This result shows that the effect of the child allowance depends on whether income growth ceases or continues in the long run.
Trends in age distribution of participants in a self-covered and a public expense-covered health check-up programs in Japan  [PDF]
Maki Ogawa, Atsushi Imai
Health (Health) , 2012, DOI: 10.4236/health.2012.49088
Abstract: Objective: In Japan, there are unique facilities (namely Ningen Dock) of health check-up, where asymptomatic participants undergo a medical examination at their own expense. The earlier occurrence of cervical cancer and the concern on screening prompted us compare to the age distribution in the self-covered system with that of free physical check-up programs at public expense. Methods: We analyzed medical records of Japanese women, who underwent gynecological examinations at self-covered expense and at public expense between for the periods 2002-2011 and 2005-2009, respectively, restricting examinee’s age group. Results: For self-covered system, approximately 80% of the overall examinee population was occupied with three age groups 30-39, 40-49 and 50-59. The participants was extremely fewer in the over 60 years age group accounting for 10%, compared to those for the public expense-covered system, the over 60 years age group being 25%. Participant under the age of 30 years seemed to increase in chronological order in both systems. Conclusion: The level of knowledge on sexually transmitted infections may contribute to screening promotion for the younger women, while the elderly over 60 years’ attitudes toward screening may be mainly related to social-economic status and/or public expense support.
Relief of hot flashes with escitalopram in non-depressed menopausal women in Japan: Results of a retrospective analysis  [PDF]
Chikako Mori, Atsushi Imai
Health (Health) , 2012, DOI: 10.4236/health.2012.410136
Abstract: Purpose: Hormone therapy (estrogen with or without progestin) remains the gold standard treatment for hot flashes in menopausal women, but concerns for the risk of hormone therapy have resulted in its decline and a demand for nonhormonal treatments with demonstrated efficacy for hot flashes. Aim of this study was to examine the efficacy of selective serotonin reuptake inhibitor escitalopram on hot flashes in a healthy sample of non-depressant menopausal women in Japan. Methods: We retrospectively analyzed the medical records of 11 menopausal patients with hot flashes, who received escitalopram (10 mg daily) for 2 weeks between March and August 2012. Hot flashes severities and scores were recorded on a scale of 0 to 10 points, at beginning and end of 2 weeks treatment. Results: At 2 weeks of therapy, 9 of 11 patients reported significant decreases in hot flash frequency and severity, but the remission of the symptom was not observed in 2 patients. Speed of relief from hot flashes was rapid (within one week). Conclusions: Escitalopram 10 mg/day may be a prompt and effective option for treating hot flashes in menopausal women who do not want to use hormone replacement therapy.
Grand potential formalism of interfacial thermodynamics for critical nucleus  [PDF]
Atsushi Mori, Yoshihisa Suzuki
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.55078
Abstract:

In nucleation theories, the work of formation of a nucleus is often denoted by W = ΔG. This convention misleads that the nucleation should be considered in the isothermal-isobaric system. However, the pressure in the system with a nucleus is no longer uniform due to Laplace’s equation. Instead, the chemical potential is uniform throughout the system for the critical nucleus. Therefore, one can consider the nucleation in the grand ensemble properly. Accordingly, W is found to be the grand potential difference and the interfacial tension is also turned to be an interfacial excess grand potential. This treatment is not entirely new; however, to explicitly treat in the grand potential formalism is for the first time. We have successfully given an overwhelmingly clear description.

Optimization Scheme Based on Differential Equation Model for Animal Swarming  [PDF]
Takeshi Uchitane, Atsushi Yagi
Open Journal of Optimization (OJOp) , 2013, DOI: 10.4236/ojop.2013.22007
Abstract:

This paper is devoted to introducing an optimization algorithm which is devised on a basis of ordinary differential equation model describing the process of animal swarming. By several numerical simulations, the nature of the optimization algorithm is clarified. Especially, if parameters included in the algorithm are suitably set, our scheme can show very good performance even in higher dimensional problems.

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