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Search Results: 1 - 10 of 510 matches for " Isao Ohtsuka "
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Membrane Incorporation, Channel Formation, and Disruption of Calcium Homeostasis by Alzheimer's β-Amyloid Protein
Masahiro Kawahara,Isao Ohtsuka,Shoko Yokoyama,Midori Kato-Negishi,Yutaka Sadakane
International Journal of Alzheimer's Disease , 2011, DOI: 10.4061/2011/304583
Abstract: Oligomerization, conformational changes, and the consequent neurodegeneration of Alzheimer's β-amyloid protein (AβP) play crucial roles in the pathogenesis of Alzheimer's disease (AD). Mounting evidence suggests that oligomeric AβPs cause the disruption of calcium homeostasis, eventually leading to neuronal death. We have demonstrated that oligomeric AβPs directly incorporate into neuronal membranes, form cation-sensitive ion channels (“amyloid channels”), and cause the disruption of calcium homeostasis via the amyloid channels. Other disease-related amyloidogenic proteins, such as prion protein in prion diseases or α-synuclein in dementia with Lewy bodies, exhibit similarities in the incorporation into membranes and the formation of calcium-permeable channels. Here, based on our experimental results and those of numerous other studies, we review the current understanding of the direct binding of AβP into membrane surfaces and the formation of calcium-permeable channels. The implication of composition of membrane lipids and the possible development of new drugs by influencing membrane properties and attenuating amyloid channels for the treatment and prevention of AD is also discussed. 1. Introduction Alzheimer’s disease (AD) is a severe type of senile dementia, affecting a large portion of elderly people worldwide. It is characterized by profound memory loss and inability to form new memories. The pathological hallmarks of AD are the presence of numerous extracellular deposits, termed senile plaques, and intraneuronal neurofibrillary tangles (NFTs). The degeneration of synapses and neurons in the hippocampus or cerebral cortex is also observed [1]. The major components of NFTs are phosphorylated tau proteins, and that of senile plaques are β-amyloid proteins (AβPs). Although the precise cause of AD remains elusive, it is widely accepted that oligomerization of AβP and the consequent neurodegeneration might be the cause of neuronal death in AD patients [2, 3]. There is considerable interest regarding the mechanism by which AβPs cause neurodegeneration. AβPs have been reported to cause various adverse effects on neuronal survivals, such as the production of reactive oxygen species, the induction of cytokines, the induction of endoplasmic reticulum (ER) stresses, and the abnormal increase in intracellular calcium levels ([Ca2+]i) [4]. These adverse effects are complex and may be interwoven. Of these effects, the disruption of calcium homeostasis could be the earliest and primary event, since Ca2+ ions are essential for various neuronal functions. The
Comparison of the Sampling Efficiency in Spatial Autoregressive Model  [PDF]
Yoshihiro Ohtsuka, Kazuhiko Kakamu
Open Journal of Statistics (OJS) , 2015, DOI: 10.4236/ojs.2015.51002
Abstract: A random walk Metropolis-Hastings algorithm has been widely used in sampling the parameter of spatial interaction in spatial autoregressive model from a Bayesian point of view. In addition, as an alternative approach, the griddy Gibbs sampler is proposed by [1] and utilized by [2]. This paper proposes an acceptance-rejection Metropolis-Hastings algorithm as a third approach, and compares these three algorithms through Monte Carlo experiments. The experimental results show that the griddy Gibbs sampler is the most efficient algorithm among the algorithms whether the number of observations is small or not in terms of the computation time and the inefficiency factors. Moreover, it seems to work well when the size of grid is 100.
Expression of p27(Kip1), a Cyclin-Dependent Kinase Inhibitor, in Human Peripheral Blood Mononuclear Cells Is Inversely Associated with Potential Carcinogenic Risk in Obese Type 2 Diabetic Individuals Relative to Lean Normal Controls  [PDF]
Isao Eto
American Journal of Molecular Biology (AJMB) , 2014, DOI: 10.4236/ajmb.2014.43013
Abstract:

Introduction: The consensus report issued jointly by the American Diabetes Association and the American Cancer Society stated that “type 2 diabetes and cancer share many risk factors, but potential biologic links between the two diseases are incompletely understood”. Interestingly, however, a recent report suggested that the expression of p27(Kip1), a cell cycle repressor protein, in the rodent liver was inversely associated with potential carcinogenic risk in the genetic rodent models of diabetic obesity. p27 is a cyclin-dependent kinase inhibitor that, when down-regulated, allows the progression of the cell cycle from G1 to S phase, thereby increasing the risk of developing cancer. Objective: The objective of the study described below was to extend the results of the recent report on the expression of p27 in the livers of obese, diabetic rodents to the humans and investigate whether the expression of p27 in the human peripheral blood mononuclear cells (PBMCs) might also be inversely associated with potential carcinogenic risk in obese type 2 diabetic individuals relative to the lean normal controls. Methods: Western immunoblot analysis was performed to evaluate the expression of p27 and the two most relevant upstream molecular signaling pathways of the expression of p27, namely 4E-BP1 and MNK1, in human PBMCs obtained from obese type 2 diabetic individuals relative to the lean normal controls. Results: First, expression of p27 in human PBMCs was significantly down-regulated in obese type 2 diabetic individuals relative to the lean normal controls. Secondly, expression of p27 in human PBMCs was also significantly down-regulated in obese type 2 diabetic African Americans relative even to the obese type 2 diabetic Caucasian Americans. Conclusions: Expression of p27 in human PBMCs was inversely associated with potential carcinogenic risk in obese type 2 diabetes relative to the lean normal controls.

Expression of p27Kip1, A Cell Cycle Repressor Protein with Dual Roles for Both Cancer Prevention and Promotion, Is Regulated Primarily at the Level of Unusual p27Kip1 mRNA—A Short Concept Proposal  [PDF]
Isao Eto
American Journal of Molecular Biology (AJMB) , 2018, DOI: 10.4236/ajmb.2018.83016
Abstract: The p27Kip1 is a cell cycle repressor protein that regulates primarily the cell cycle transition from G1 to S phase and hence the DNA replication is in the S phase and cell division in the M phase. Expression of p27Kip1 protein has dual roles for both cancer prevention and promotion. For example, numerous nutritional and chemopreventive anti-cancer agents specifically increase the expression of p27Kip1 protein without directly affecting the expression of any other cell cycle regulatory proteins. On the other hand, pro-cancer agents (like glucose, insulin and other growth factors frequently seen in obesity and/or diabetes) specifically decrease the expression of p27Kip1 protein without directly affecting the expression of any other cell cycle regulatory proteins. Unlike expression of any other cell cycle regulatory proteins, expression of p27Kip1 protein is very unusual. The mRNA of p27Kip1 has a very long and unusual 5’-untranslated region (from -575 to -1 in human). It appears that the 5’-untranslated region of p27Kip1 mRNA forms two alternative secondary structures. One increases the expression of p27Kip1 protein when anti-cancer agents are added and another decrease the expression of p27K1p1 when pro-cancer agents are added. For this short concept proposal, Dr. Albert Einstein’s “visualized thought experiments (German: Gedanken experiment) were used as a fundamental tool for understanding how either anti- or pro-cancer agents bring the primary structure of the 5’-untranslated region of p27Kip1 mRNA into two alternative secondary structures, thereby either increasing or decreasing, respectively, the translation initiation of p27Kip1 protein.
Statistical Survey of Deaths from Nonmelanoma Skin Cancer in Japan during 54 Years
Hisashi Ohtsuka
Journal of Skin Cancer , 2011, DOI: 10.1155/2011/293926
Abstract: The author analyzed the annual trends in the number of deaths from nonmelanoma skin cancer (NMSC) from 1955 to 2008 in Japan on the basis of the data from the Vital Statistics of Japan. The general trends in the number of deaths from NMSC were downward between 1979 to 1994, but upward after 1995. The general trends in age-standardized death rates were roughly downward, although the death rates plateaued after 1995. The recent annual increased ratio of deaths from NMSC was 3.8% (95% confidence interval: 2.7?~?4.9%). The number and proportion of deaths from NMSC among the elderly were increasing in Japan. For females, more than 50% of the deaths occurred recently at or after 85?years of age, whereas, for males, this proportion was at or after 75?years of age, nearly reaching at or after 80?years of age. 1. Introduction The incidence of nonmelanoma skin cancer (NMSC) has been increasing during the past half century in many countries [1–6]. Authors performed the analysis of changing trends in the number of deaths from NMSC in Japan from 1955 to 2000 [7]. This time, the author expanded the period of survey to 2008 and revised the analysis, using the new WHO standard population which is effective for the period 2000–2025 [8]. 2. Material and Methods The annual trends in the number of deaths from NMSC in Japan from 1955 to 2008, those in age-standardized death rates, those in 3-year moving average, those by 5-year age group, those by sex and age group, and those in the proportion of deaths by sex and age group were investigated on the basis of the data from the Vital Statistics of Japan, Statistics and Information Department, Minister's Secretariat, Ministry of Health, Labor and Welfare. The corresponding revisions of the International Classification of Diseases (ICD) and codes were ICD-6 code 191 in 1955–1957, ICD-7 code 191 in 1958–1967, ICD-8 code 173 in 1968–1978, ICD-9 code 173 in 1979–1994, and ICD-10 code C44 in 1995–2008, respectively. The author, however, treated the results continuously from 1955 to 1967, because there was no difference between ICD-6 and ICD-7 concerning NMSC. The author treated the remaining revisions as discontinuous, because there was a minor difference between ICD-6/-7, ICD-8, ICD-9, and ICD-10. The author judged that it would be possible to obtain the general annual trends in the number of deaths from NMSC in Japan for 54 years, although, strictly speaking, there were four times minor changes of ICD classifications concerning NMSC between these periods. The death rates were adjusted every year using the new WHO world standard
Corrosion Protection of Steels by Conducting Polymer Coating
Toshiaki Ohtsuka
International Journal of Corrosion , 2012, DOI: 10.1155/2012/915090
Abstract: The corrosion protection of steels by conducting polymer coating is reviewed. The conducting polymer such as polyaniline, polypyrrole, and polythiophen works as a strong oxidant to the steel, inducing the potential shift to the noble direction. The strongly oxidative conducting polymer facilitates the steel to be passivated. A bilayered PPy film was designed for the effective corrosion protection. It consisted of the inner layer in which phosphomolybdate ion, (PMo), was doped and the outer layer in which dodecylsulfate ion (DoS) was doped. The inner layer stabilized the passive oxide and the outer possessed anionic perm-selectivity to inhibit the aggressive anions such as chloride from penetrating through the PPy film to the substrate steel. By the bilayered PPy film, the steel was kept passive for about 200?h in 3.5% sodium chloride solution without formation of corrosion products. 1. Introduction Since the investigation of Shirakawa et al. on conducting polyacetylene, various applications of conducting polymer have been reported [1]. Utilization of the conducting polymer for corrosion protection coating is one of these applications, and many papers have been presented in the last decade. Preparation of polyacetylen was made by oxidation in gaseous phase; however, at present, the conducting polymers such as polyaniline (PAni), polypyrrole (PPy), and polythiophen (Pthio) in Figure 1 for the corrosion protection have been prepared by electrochemical oxidation in liquid phase. Figure 1: Typical conducting polymers: (a) polypyrrole (PPy), (b) polythiophen (PThio), and (c) polyaniline (PAni). For application of the conducting polymer to corrosion protection, DeBerry was firstly reported in 1985, who presented that the stainless steel covered by PAni was kept in the passive state for relatively long period in sulfuric acid solution [2]. Wessling then pointed out that the conducting polymer coating of polyaniline and polypyrrole possibly possessed self-healing properties, in which the passive oxide between the substrate metal and the conducting polymer could be spontaneously reformed at a flawed site by oxidative capability of the conducting polymer [3]. When anodic potentials are applied to electrodes covered by the conducting polymers shown in Figure 1 after the polymerization, the oxidative property is provided in addition to the conductivity. The ability of the conducting polymer to oxidize the substrate steels allows potential of steels to be shifted to the passive state, in which the steels are protected by the passive oxide formed beneath the
Views on luck and winning, self-control, and gaming service expectations of culturally and linguistically diverse Australian poker machine gamblers
Keis Ohtsuka
Asian Journal of Gambling Issues and Public Health , 2013, DOI: 10.1186/2195-3007-3-9
Abstract: Despite an increase in social diversity in recent years, the role of culture in gambling cognition and behaviour is not fully understood. Qualitative interviews examined subjective views of Australian poker machine (electronic gaming machine) gamblers from culturally and linguistically diverse (CALD) backgrounds. A total of 49 Australian poker machine gamblers from CALD backgrounds (20 Chinese, 15 Vietnamese and 14 Greek Australians) were interviewed regarding their views on the concept of luck and winning, self control, subjective meanings of gambling and gaming venue service expectations. The current findings showed that the majority of poker machine gamblers from CALD backgrounds believed that the payout of poker machines occurred randomly. Luck was defined, therefore, as being at the right place at the right time when the poker machine pays out. However, a small number of interviewees maintained an optimistic view about achieving gambling wins by using a certain system. While experienced gamblers and those with secondary school qualification or lower regarded poker machine gambling as a random potluck, a few young players with university education subscribed to a more elaborate endorsement in favour of their own systems to win on the poker machine. Australian CALD gamblers valued friendly professional service from gaming venue staff (e.g., courteous customer service, affordable, quality food and drink, personal greetings using first names) but disliked intrusive or over-friendly interactions. Implications of the findings on the role of superstition and cognition on gamblers' beliefs are discussed.
TOPICAL REVIEW: Structural control of Fe-based alloys through diffusional solid/solid phase transformations in a high magnetic field
Hideyuki Ohtsuka
Science and Technology of Advanced Materials , 2008,
Abstract: A magnetic field has a remarkable influence on solid/solid phase transformations and it can be used to control the structure and function of materials during phase transformations. The effects of magnetic fields on diffusional solid/solid phase transformations, mainly from austenite to ferrite, in Fe-based alloys are reviewed. The effects of magnetic fields on the transformation temperature and phase diagram are explained thermodynamically, and the transformation behavior and transformed structures in magnetic fields are discussed.
Synthesis and Solvatochromic Behavior of Hexaphenylbenzenes and Indeno[1,2-b]fluorene Derivatives with Hydroxy Groups  [PDF]
Isao Yamaguchi, Kenta Tsuchie
International Journal of Organic Chemistry (IJOC) , 2012, DOI: 10.4236/ijoc.2012.23027
Abstract: Hexakis(4-methoxyphenyl)benzene (HPB-OMe(1)) and hexakis(2,6-dimethyl-4-methoxyphenyl)benzene (HPB-OMe(2)) were synthesized via organometallic complex catalysis. The treatment of HPB-OMe(1) with FeCl3 caused cyclodehydrogenation at two positions to yield an oligophenylene with an indeno[1,2-b]fluorene structure (IF-OMe). Deprotection of the methoxy groups of these compounds was conducted by treatment with BBr3. Deprotonation of the OH groups of HPB-OH(1), HPB-OH(2), and IF-OH through treatment with NaH caused a bathochromic shift in the absorption and photoluminescence (PL) peaks. The bathochromic shift of the deprotonated species increased with the donor number (DN) of the solvents. These observations can be explained as the consequence of intramolecular charge transfer (ICT) from the ONa groups to the inner benzene rings.
Synthesis, Characterization and Charge-Discharge Properties of Layer-Structure Lithium Zinc Borate, LiZnBO3  [PDF]
Isao Tsuyumoto, Akihiro Kihara
Materials Sciences and Applications (MSA) , 2013, DOI: 10.4236/msa.2013.44030
Abstract:

Layer-Structure lithium zinc borate, LiZnBO3, is prepared by a solid state reaction of LiOH·H2O, ZnO, and H3BO3 at 1000°C for 10 h. Highly preferred orientation and a layer-structure are observed in the powder XRD patterns and the SEM images, respectively. The Rietveld analysis indicates a monoclinic unit cell with space group C2/c, and the lattice parameters are refined as a = 8.827 ?, b = 5.078 ?, c = 6.171 ?, and β = 118.86°. LiZnBO3 shows the capacity of 17 mAh/g between 1.3 V and 4.3 V (vs. Li/Li+) larger than ZnO.

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