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Search Results: 1 - 10 of 347 matches for " Hidemi Kurihara "
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RUNX3 Has an Oncogenic Role in Head and Neck Cancer
Takaaki Tsunematsu, Yasusei Kudo, Shinji Iizuka, Ikuko Ogawa, Tsuyoshi Fujita, Hidemi Kurihara, Yoshimitsu Abiko, Takashi Takata
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0005892
Abstract: Background Runt-related transcription factor 3 (RUNX3) is a tumor suppressor of cancer and appears to be an important component of the transforming growth factor-beta (TGF-?)-induced tumor suppression pathway. Surprisingly, we found that RUNX3 expression level in head and neck squamous cell carcinoma (HNSCC) tissues, which is one of the most common types of human cancer, was higher than that in normal tissues by a previously published microarray dataset in our preliminary study. Therefore, here we examined the oncogenic role of RUNX3 in HNSCC. Principal Findings Frequent RUNX3 expression and its correlation with malignant behavior were observed in HNSCC. Ectopic RUNX3 overexpression promoted cell growth and inhibited serum starvation-induced apoptosis and chemotherapeutic drug induced apoptosis in HNSCC cells. These findings were confirmed by RUNX3 knockdown. Moreover, RUNX3 overexpression enhanced tumorsphere formation. RUNX3 expression level was well correlated with the methylation status in HNSCC cells. Moreover, RUNX3 expression was low due to the methylation of its promoter in normal oral epithelial cells. Conclusions/Significance Our findings suggest that i) RUNX3 has an oncogenic role in HNSCC, ii) RUNX3 expression observed in HNSCC may be caused in part by demethylation during cancer development, and iii) RUNX3 expression can be a useful marker for predicting malignant behavior and the effect of chemotherapeutic drugs in HNSCC.
Is the Tokyo Foreign Exchange Market Efficient from Two Perspectives of Forward Bias and Anomaly?  [PDF]
Yutaka Kurihara
Modern Economy (ME) , 2011, DOI: 10.4236/me.2011.24067
Abstract: This paper examines the efficiency of the Tokyo Foreign Exchange Market from two perspectives. One is whether or not forward bias in this market has existed and the other is the effect of interventions in the market with a focus on whether or not a day-of-the-week anomaly exists in it. Empirical results show that forward exchange rates are a biased predictor of future spot exchange rates; however, there are some anomalies in the market. The findings suggest the conclusion that this market has not been completely efficient.
The Impact of Regional Trade Agreements on International Trade  [PDF]
Yutaka Kurihara
Modern Economy (ME) , 2011, DOI: 10.4236/me.2011.25094
Abstract: The gravity model of international trade states that bilateral trade flows based on the economic sizes and distances between two units can be used to examine reasons for international trade. Regional Trade Agreements (RTAs) have appeared recently and have increased markedly in number; however, despite their importance, little study has been performed to analyze the effects of RTAs on international trade. The difference between RTAs and world trade organizations (WTO) is important. Studies of currency integration have appeared recently; however, most assume that currency integration varies the level of international trade between countries by making the proportion constant. This paper eliminates this socalled constant hypothesis and indicates that RTAs alters the slope of the relationship between countries and promote international trade. Empirical analysis indicates that the proportion is not constant. Also, this study shows that RTAs promote international trade more in OECD countries than in non-OECD countries.
Is the WTO Truly Effective?  [PDF]
Yutaka Kurihara
iBusiness (IB) , 2012, DOI: 10.4236/ib.2012.42014
Abstract: Whether or not the World Trade Organization (WTO) has promoted international trade is under dispute. This article uses a revised traditional gravity model to conduct empirical examination of this problem and found that WTO has recently promoted international trade and that the degree of increase is larger in developed countries than in developing ones. Moreover, regional trade agreements (RTA), currency unions, GDP, and distance are related to the increase of international trade along with the effects of WTO activities. On the other hand, the effect of distance on international trade has been decreasing. Improvements in information technology (IT) may have influenced this finding.
Visualization of a Laminar Necklace Vortex System in Front of a Vertical Rectangular Plate on a Ground Wall  [PDF]
Yasuhiro Nakahara, Hidemi Yamada
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2015, DOI: 10.4236/jfcmv.2015.32008
Abstract: Various properties of a necklace vortex system formed around a rectangular plate standing vertically on a flat ground wall were investigated by visualizations produced by injecting fluorescent dye into a water channel flow. As a result, it was found that the necklace vortex pattern had three steady systems depending on the Reynolds number Reh, the relative height h/δ of the rectangular plate compared with the laminar boundary layer thickness and the aspect ratio w/h. As it is expected that the aspect ratio of the rectangular plate will typify the projected area configuration of various three-dimensional bodies, the aspect ratio is varied widely from 0.5 to 7.0. The transitional boundaries of Reh and h/δ in the 2-vortex, 4-vortex and 6-vortex systems for each aspect ratio decreased when w/h < 3.0, and increased when w/h ≥ 3.0 as w/h increased. The x-direction length of the main vortex position XV1/h was almost constant when w/h < 3.0, and decreased when w/h ≥ 3.0 as Reh increased. Then, the separation length r1/h increased when w/h < 3.0 and Reh < 1000, and became almost constant when w/h ≥ 3.0 and Reh ≥ 1000 as w/h and Reh increased. Moreover, the increase of r1/h is notably rapid when w/h < 3.0.
Novel Insights into the Interplay between Apoptosis and Autophagy
Hidemi Rikiishi
International Journal of Cell Biology , 2012, DOI: 10.1155/2012/317645
Abstract: For several decades, apoptosis has taken center stage as the principal mechanism of programmed cell death (type I cell death) in mammalian tissues. Autophagic cell death (type II) is characterized by the massive accumulation of autophagic vacuoles in the cytoplasm of cells. The autophagic process is activated as an adaptive response to a variety of extracellular and intracellular stresses, including nutrient deprivation, hormonal or therapeutic treatment, pathogenic infection, aggregated and misfolded proteins, and damaged organelles. Increasing evidence indicates that autophagy is associated with a number of pathological processes, including cancer. The regulation of autophagy in cancer cells is complex since it can enhance cancer cell survival in response to certain stresses, while it can also act to suppress the initiation of cancer growth. This paper focused on recent advances regarding autophagy in cancer and the techniques currently available to manipulate autophagy. 1. Introduction Current cancer therapies are based on the surgical removal of solid tumor masses, usually combined with a series of chemical (chemotherapy) or physical (radiotherapy) treatments; however, chemotherapy has reached a plateau of efficacy as a treatment modality with the emergence of resistant tumors. Despite the wide variety of mechanisms, most new drugs are thought to ultimately induce apoptosis of tumor cells through mitochondrial and/or death-receptor pathways, although these pathways are often defective in cancer. More recently, other mechanisms of cell death have emerged as potential novel mechanisms for cancer therapies to induce cell death. Macroautophagy (hereafter referred to autophagy) is a eukaryotic, evolutionarily conserved homeostatic process in which organelles and bulk proteins are turned over by lysosomal activity [1]. Autophagy and apoptosis may be interconnected and even simultaneously regulated by the same trigger in tumor cells. In periods of metabolic stress, autophagy provides ATP and other macromolecules as energy sources to enable cell survival; however, if the intensity or duration of metabolic stress is excessive, cells may progress to autophagic programmed cell death, which is distinct from apoptosis [2]. In contrast, whether autophagy contributes to the antitumor effect of chemotherapeutic drugs or to drug resistance is largely unknown. In addition, there is no current consensus on how to manipulate autophagy to improve clinical outcomes. This paper describes the role of autophagy with a particular focus on the roles of cytoplasmic organelles
Autophagic and Apoptotic Effects of HDAC Inhibitors on Cancer Cells
Hidemi Rikiishi
Journal of Biomedicine and Biotechnology , 2011, DOI: 10.1155/2011/830260
Abstract: Because epigenetic alterations are believed to be involved in the repression of tumor suppressor genes and the promotion of tumorigenesis in cancers, novel compounds endowed with histone deacetylase (HDAC) inhibitory activity are an attractive therapeutic approach. Indeed, the potential of HDAC inhibitors for cancer therapy has been explored in preclinical models, and some agents approved for hematologic malignancies have reached the clinical setting. HDAC inhibitors are able to mediate the induction of both apoptosis and autophagy, which are related to anticancer activity in a variety of cancer cell lines. Given the inherent resistance to apoptosis that characterizes cancer, the targeting of alternative pathways is an attractive strategy to improve anti-tumor therapy. The activation of autophagy represents novel cancer treatment targets. This paper aims to critically discuss how the anticancer potential of HDAC inhibitors may elicit a response to human cancers through different cell pathways leading to cell death.
Possible Role of Autophagy in the Treatment of Pancreatic Cancer with Histone Deacetylase Inhibitors
Hidemi Rikiishi
Cancers , 2010, DOI: 10.3390/cancers2042026
Abstract: Pancreatic cancer is a lethal disease and notoriously difficult to treat. Only a small proportion is curative by surgical resection, whilst standard chemotherapy for patients with advanced disease has only a modest effect with substantial toxicity. Clearly there is a need for the continual development of novel therapeutic agents to improve the current situation. Currently, there is a bulk of data indicating the important function of autophagy in cancer. While genetic evidence indicates that autophagy functions as a tumor suppressor, it is also apparent that autophagy can promote the survival of established tumors under stress conditions and in response to chemotherapy. This review provides a spectrum of potential pharmacological agents and autophagic approaches to enhance cell killing in pancreatic cancer.
Study of Integral Variable Structure Control Method for Stability of SI Engine Idling Speed  [PDF]
Yang Zhang, Nobuo Kurihara
Journal of Software Engineering and Applications (JSEA) , 2010, DOI: 10.4236/jsea.2010.38094
Abstract: The intake air control system of a gasoline engine is a typical nonlinear system, and included among the adverse fac-tors that always induce poor idle-speed control stability are dead time and disturbances in the intake air control process. In this paper, to improve the responsiveness when idling with regard to disturbances, a mean-value engine model (MVEM) with dead time was constructed as the control object, and the two servo structures of sliding mode control (SMC) were studied for better idle control performance, especially in transient process of speed change. The simulation results confirmed that under the constraint condition of control input, the robustness of idle speed control that is being subjected to torque disturbances and noise disturbances can be greatly improved by use of the servo structure II.
Is Consumption in the United States and Japan Too Much or Too Little?  [PDF]
Yutaka Kurihara, Kei Tomimura
iBusiness (IB) , 2012, DOI: 10.4236/ib.2012.43029
Abstract: This article reports on the results of an empirical examination of whether consumption in the United States and Japan is too much or too little relative to productivity in these countries (1993-2011). Findings reveal some clear and common characteristics of both countries for the sample period. The most typical one occurred during financial crises around 2008, which is often called the Lehman shock. In both countries, consumers had considerably reduced consumption around that period. The IT boom collapse at the beginning of the 2000s also diminished consumption in the United States. This paper examines impulse responses to trace the effect of a productivity shock to one of the innovations on the current and future value of consumption. Findings indicate that the effect of the shock of productivity on consumption is long both countries
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