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Search Results: 1 - 10 of 1694 matches for " Hideyuki Takeuchi "
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Gap junctions and hemichannels composed of connexins: potential therapeutic targets for neurodegenerative diseases
Hideyuki Takeuchi,Akio Suzumura
Frontiers in Cellular Neuroscience , 2014, DOI: 10.3389/fncel.2014.00189
Abstract: Microglia are macrophage-like resident immune cells that contribute to the maintenance of homeostasis in the central nervous system (CNS). Abnormal activation of microglia can cause damage in the CNS, and accumulation of activated microglia is a characteristic pathological observation in neurologic conditions such as trauma, stroke, inflammation, epilepsy, and neurodegenerative diseases. Activated microglia secrete high levels of glutamate, which damages CNS cells and has been implicated as a major cause of neurodegeneration in these conditions. Glutamate-receptor blockers and microglia inhibitors (e.g. minocycline) have been examined as therapeutic candidates for several neurodegenerative diseases; however, these compounds exerted little therapeutic benefit because they either perturbed physiological glutamate signals or suppressed the actions of protective microglia. The ideal therapeutic approach would hamper the deleterious roles of activated microglia without diminishing their protective effects. We recently found that abnormally activated microglia secrete glutamate via gap-junction hemichannels on the cell surface. Moreover, administration of gap-junction inhibitors significantly suppressed excessive microglial glutamate release and improved disease symptoms in animal models of neurologic conditions such as stroke, multiple sclerosis, amyotrophic lateral sclerosis, and Alzheimer’s disease. Recent evidence also suggests that neuronal and glial communication via gap junctions amplifies neuroinflammation and neurodegeneration. Elucidation of the precise pathologic roles of gap junctions and hemichannels may lead to a novel therapeutic strategies that can slow and halt the progression of neurodegenerative diseases.
Endoscopic Neck Surgery for Thyroid Carcinoma
Hiroya Kitano,Takashi Kinoshita,Hideyuki Kataoka,Masamitsu Hirano,Eiji Takeuchi,Kazutomo Kitajima,Masaki Fujimura
Diagnostic and Therapeutic Endoscopy , 2001, DOI: 10.1155/dte.7.135
Abstract: In the past 5 years, endoscopic neck surgery has been performed by various surgeons in Japan. However, many problems remain to be solved, including indications for this related in malignant thyroid tumors. For small thyroid cancers and legions suspected of malignancy, we found that we could obtain radicality in endoscopic neck surgery that was comparable to that attainable by conventional methods. Here, we describe our recent endoscopic surgical experience in five patients with preoperative diagnoses of definite or suspected thyroid carcinoma.
Multi-Name Extension to the Credit Grades and an Efficient Monte Carlo Method  [PDF]
Hideyuki Takada
Journal of Mathematical Finance (JMF) , 2014, DOI: 10.4236/jmf.2014.43017
Abstract:

In this paper, we present a multi-name incomplete information structural model which possess the contagion mechanism and its efficient Monte Carlo algorithm based on Interacting Particle System. Along with the Credit Grades, which is industrially used single-name credit model, we suppose that investors can observe firm values and defaults but are not informed of the threshold level at which a firm is deemed to default. Additionally, in order to model the possibility of crisis normalization, we introduce the concept of memory period after default. During the memory period after a default, public investors remember when the previous default occurred and directly reflect that information for updating their belief. When the memory period after a default finish, investors forget about that default and shift their interest to recent defaults if exist. One of the variance reduction techniques, relying upon Interacting Particle System, is combined with the standard Monte Carlo method to address the rare but critical events represented by the tail of loss distribution of portfolio.

The neuroprotective effects of milk fat globule-EGF factor 8 against oligomeric amyloid β toxicity
Endong Li, Mariko Noda, Yukiko Doi, Bijay Parajuli, Jun Kawanokuchi, Yoshifumi Sonobe, Hideyuki Takeuchi, Tetsuya Mizuno, Akio Suzumura
Journal of Neuroinflammation , 2012, DOI: 10.1186/1742-2094-9-148
Abstract: The release of MFG-E8 from microglia treated with conditioned medium from neurons exposed to neurotoxic substances, glutamate or oligomeric amyloid β (oAβ) was measured by ELISA. The neuroprotective effects of MFG-E8 and MFG-E8???induced microglial phagocytosis of oAβ were assessed by immunocytochemistry. The effects of MFG-E8 on the production of the anti-oxidative enzyme hemeoxygenase-1 (HO-1) were determined by ELISA and immunocytochemisty.MFG-E8 was induced in microglia treated with conditioned medium from neurons that had been exposed to neurotoxicants, glutamate or oAβ. MFG-E8 significantly attenuated oAβ-induced neuronal cell death in a primary neuron???microglia coculture system. Microglial phagocytosis of oAβ was accelerated by MFG-E8 treatment due to increased CD47 expression in the absence of neurotoxic molecule production, such as tumor necrosis factor-α, nitric oxide, and glutamate. MFG-E8???treated microglia induced nuclear factor E(2)???related factor 2 (Nrf2)???mediated HO-1 production, which also contributed to neuroprotection.These results suggest that microglia release MFG-E8 in response to signals from degenerated neurons and that MFG-E8 protects oAβ-induced neuronal cell death by promoting microglial phagocytic activity and activating the Nrf2-HO-1 pathway. Thus, MFG-E8 may have novel roles as a neuroprotectant in neurodegenerative conditions.
Fingolimod Phosphate Attenuates Oligomeric Amyloid β–Induced Neurotoxicity via Increased Brain-Derived Neurotrophic Factor Expression in Neurons
Yukiko Doi, Hideyuki Takeuchi, Hiroshi Horiuchi, Taketo Hanyu, Jun Kawanokuchi, Shijie Jin, Bijay Parajuli, Yoshifumi Sonobe, Tetsuya Mizuno, Akio Suzumura
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061988
Abstract: The neurodegenerative processes that underlie Alzheimer's disease are mediated, in part, by soluble oligomeric amyloid β, a neurotoxic protein that inhibits hippocampal long-term potentiation, disrupts synaptic plasticity, and induces the production of reactive oxygen species. Here we show that the sphingosine-1-phosphate (S1P) receptor (S1PR) agonist fingolimod phosphate (FTY720-P)-a new oral drug for multiple sclerosis-protects neurons against oligomeric amyloid β-induced neurotoxicity. We confirmed that primary mouse cortical neurons express all of the S1P receptor subtypes and FTY720-P directly affects the neurons. Treatment with FTY720-P enhanced the expression of brain-derived neurotrophic factor (BDNF) in neurons. Moreover, blocking BDNF-TrkB signaling with a BDNF scavenger, TrkB inhibitor, or ERK1/2 inhibitor almost completely ablated these neuroprotective effects. These results suggested that the neuroprotective effects of FTY720-P are mediated by upregulated neuronal BDNF levels. Therefore, FTY720-P may be a promising therapeutic agent for neurodegenerative diseases, such as Alzheimer's disease.
Evidence for Aberrant Astrocyte Hemichannel Activity in Juvenile Neuronal Ceroid Lipofuscinosis (JNCL)
Maria Burkovetskaya, Nikolay Karpuk, Juan Xiong, Megan Bosch, Michael D. Boska, Hideyuki Takeuchi, Akio Suzumura, Tammy Kielian
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0095023
Abstract: Juvenile Neuronal Ceroid Lipofuscinosis (JNCL) is a lysosomal storage disease caused by an autosomal recessive mutation in CLN3 that leads to vision loss, progressive cognitive and motor decline, and premature death. Morphological evidence of astrocyte activation occurs early in the disease process and coincides with regions where neuronal loss eventually ensues. However, the consequences of CLN3 mutation on astrocyte function remain relatively ill-defined. Astrocytes play a critical role in CNS homeostasis, in part, by their ability to regulate the extracellular milieu via the formation of extensive syncytial networks coupled by gap junction (GJ) channels. In contrast, unopposed hemichannels (HCs) have been implicated in CNS pathology by allowing the non-discriminant passage of molecules between the intracellular and extracellular milieus. Here we examined acute brain slices from CLN3 mutant mice (CLN3Δex7/8) to determine whether CLN3 loss alters the balance of GJ and HC activity. CLN3Δex7/8 mice displayed transient increases in astrocyte HC opening at postnatal day 30 in numerous brain regions, compared to wild type (WT) animals; however, HC activity steadily decreased at postnatal days 60 and 90 in CLN3Δex7/8 astrocytes to reach levels lower than WT cells. This suggested a progressive decline in astrocyte function, which was supported by significant reductions in glutamine synthetase, GLAST, and connexin expression in CLN3Δex7/8 mice compared to WT animals. Based on the early increase in astrocyte HC activity, CLN3Δex7/8 mice were treated with the novel carbenoxolone derivative INI-0602 to inhibit HCs. Administration of INI-0602 for a one month period significantly reduced lysosomal ceroid inclusions in the brains of CLN3Δex7/8 mice compared to WT animals, which coincided with significant increases in astrocyte GJ communication and normalization of astrocyte resting membrane potential to WT levels. Collectively, these findings suggest that alterations in astrocyte communication may impact the progression of JNCL and could offer a potential therapeutic target.
Late Quaternary Geomorphology of the Tonami Plain and Activity of the Tonami-Heiya Fault Zone, Toyama Prefecture, Central Japan  [PDF]
Toshio Kamishima, Akira Takeuchi
International Journal of Geosciences (IJG) , 2016, DOI: 10.4236/ijg.2016.77073
Abstract: The Holocene alluvial fans and flood plains formed by the Sho and Oyabe Rivers spread out in the Tonami plain from the central through the northern parts in the Toyama Prefecture, central Japan. Along the foot of the surrounding mountains and hills, higher, middle and lower terraces of late Pleistocene-Holocene in age are distributed. These terraces have been displaced, by the reverse dip-slip activities of Tonami-heiya fault zone in a sense of upheaval in the mountains side, even during the Holocene time. We examined stratigraphic cross section utilizing borehole data and geomorphologically analyzed 5 m-DEM data in order to elucidate the fault trace of the Isurugi fault which Tonami-heiya fault zone. As the results, the northern segment of Isurugi fault seems to run along the northeastern foot of Hodatsu Hills and extends underground through the lower-most Oyabe River into the Toyama Bay. Consequently, its total length reaches about 30 km. In the southern segment, a continuous fault scarplet was recognized to cut across the lower dissected fans. The slip-rate of Isurugi fault is estimated to be 0.31 - 0.64 m/kyr. In the Hokuriku region, reverse faulting and related folding with strike in a NE-SW direction have occurred during the late Quaternary. The hinge line of block movement due to the activities of the Tonami-heiya fault zone is revealed to have shifted from the mountain side into the plain side within the Holocene time. In conclusion, the Quaternary folding and faulting associated with the crustal warping at a wavelength of about 20 km is currently in progress, causing both the subsidence of Tonami plain and the upheaval of surrounding mountains and hills.
Interactive Evolutionary Computation for Analyzing Human Awareness Mechanisms
Hideyuki Takagi
Applied Computational Intelligence and Soft Computing , 2012, DOI: 10.1155/2012/694836
Abstract: We discuss the importance of establishing awareness science and show the idea of using interactive evolutionary computation (IEC) as a tool for analyzing awareness mechanism and making awareness models. First, we describe the importance of human factors in computational intelligence and that IEC is one of approaches for the so-called humanized computational intelligence. Second, we show examples that IEC is used as an analysis tool for human science. As analyzing human awareness mechanism is in this kind of analyzing human characteristics and capabilities, IEC may be able to be used for this purpose. Based on this expectation, we express one idea for analyzing the awareness mechanism. This idea is to make an equivalent model of an IEC user using a learning model and find latent variables that connect inputs and outputs of the user model and that help to understand or explain the inputs-outputs relationship. Although there must be several definitions of awareness, this idea is based on one definition that awareness is to find out unknown variables that helps our understanding. If we establish a method for finding the latent variables automatically, we can realize an awareness model in computer. 1. Introduction The number of papers using the keywords context awareness, power awareness, location awareness, and situation awareness in the SciVerse Scopus database of Elsevier is, respectively, 6,383, 1,749, 1,688, and 257 as of February 2012. Engineering interest in these areas has increased. These engineering approaches call obtaining unknown knowledge or facts awareness. However, how do these engineering approaches differ from data mining or knowledge acquisition? Although these kind of applications are useful and important, we need other scientific approaches not only to support the engineering applications of awareness but also to extend awareness science and engineering. One such scientific approach would be analyzing the awareness mechanisms of human beings and/or animals and constructing awareness models based on these mechanisms. Once we establish their core technologies, we may be able to make a computer with using such a model be aware of something. As the result, we can expect not only to develop data mining-like applications as has been done until now but also to progress human-machine communications, the monitoring of social networks, and new areas. Analyzing awareness mechanisms and modeling them are the first important step to research performed in this direction. It is important to integrate ideas from and cooperate with those in ethology,
Photoinduced Surface Relief Grating Formation for a Single Crystal of 4-Aminoazobenzene
Hideyuki Nakano
International Journal of Molecular Sciences , 2010, DOI: 10.3390/ijms11041311
Abstract: Photoinduced surface relief grating (SRG) formation for a single crystal of 4-aminoazobenzene was investigated. It was found that SRG could be inscribed on the (001) surface of the crystal, which might suggest that the photoinduced SRG formation is a general phenomenon observed for single crystals of azobenzene-based molecules as well as for azobenzene-based amorphous systems. In addition, the dependences of the SRG formation upon the orientation of the sample crystal and upon the polarization of the writing beams were found to be different from those observed for previously reported crystalline systems.
Effect of aqueous vitamin B on the growth of blister blight pathogen, Exobasidium vexans
Hideyuki Nagao
Songklanakarin Journal of Science and Technology , 2012,
Abstract: The effect of three aqueous solution of biotin, thiamine and calcium pantothenate, on the growth of Exobasidiumvexans was examined in vitro. The germination process of basidiospores of E. vexans differed from those of the otherExobasidium species. Basidiospore germination commenced after 19.5 hr incubation and chlamydospore-like bodies wereformed after 96 hr of incubation. Addition of biotin, calcium pantothenate, and thiamine to Difco PDA and Czapek’s mediumdid not affect the proportion of germinating basidiospores. The length of germ tubes was enhanced only by addition ofthiamine in the media. Larger size germ tubes (thick germ tubes) were occasionally observed among the ordinary hyphae.Most germlings of basidiospores developed chlamydospore-like bodies or autolysed on the media. Thick germ tubesfrequently appeared on the calcium pantothenate amended media and developed into a colony when these hyphae weretransferred to new calcium pantothenate amended media. However, further transfer of colonies did not successfully bring anew colony to grow on the calcium pantothenate amended media. Vitamin B5, calcium pantothenate, was only partially effective in generating the thick germ tubes and to induce the initial colony formation, whereas amendment of biotin and thiamineto the media did not induce visible colony growth.
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