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Search Results: 1 - 10 of 1514 matches for " Masaaki Nakayama "
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Hypnostics for patients with lung cancer
Sumi Masaaki,Satoh Hiroaki,Nakayama Mika,Ishikawa Hiroichi
Archive of Oncology , 2003, DOI: 10.2298/aoo0304282s
Association between a Polymorphism of Aminolevulinate Dehydrogenase (ALAD) Gene and Blood Lead Levels in Japanese Subjects
Koichi Miyaki,Htay Lwin,Katsunori Masaki,Yixuan Song,Yoshimitsu Takahashi,Masaaki Muramatsu,Takeo Nakayama
International Journal of Environmental Research and Public Health , 2009, DOI: 10.3390/ijerph6030999
Abstract: This cross-sectional study investigated the relationship between the aminolevulinate dehydrogenase (ALAD) genotype and blood lead levels among 101 Japanese workers. Blood lead concentration measurement, biomarkers, and genotyping were performed. The minor allele frequency (MAF) for ALAD (ALAD2) was 0.08. Although the blood lead level in the subjects with heterozygous GC genotype was significantly higher than those with homozygous GG genotype, there were no significant differences for hemoglobin, hematocrit, serum and urinary ALA levels among genotypes. ALAD2 genotype was significantly associated with the blood lead concentration, even in the environmental lead exposed subjects. Further confirmation with a large sample size is needed.
Transcranial Extracellular Impedance Control (tEIC) Modulates Behavioral Performances
Ayumu Matani, Masaaki Nakayama, Mayumi Watanabe, Yoshikazu Furuyama, Atsushi Hotta, Shotaro Hoshino
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0102834
Abstract: Electric brain stimulations such as transcranial direct current stimulation (tDCS), transcranial random noise stimulation (tRNS), and transcranial alternating current stimulation (tACS) electrophysiologically modulate brain activity and as a result sometimes modulate behavioral performances. These stimulations can be viewed from an engineering standpoint as involving an artificial electric source (DC, noise, or AC) attached to an impedance branch of a distributed parameter circuit. The distributed parameter circuit is an approximation of the brain and includes electric sources (neurons) and impedances (volume conductors). Such a brain model is linear, as is often the case with the electroencephalogram (EEG) forward model. Thus, the above-mentioned current stimulations change the current distribution in the brain depending on the locations of the electric sources in the brain. Now, if the attached artificial electric source were to be replaced with a resistor, or even a negative resistor, the resistor would also change the current distribution in the brain. In light of the superposition theorem, which holds for any linear electric circuit, attaching an electric source is different from attaching a resistor; the resistor affects each active electric source in the brain so as to increase (or decrease in some cases of a negative resistor) the current flowing out from each source. From an electrophysiological standpoint, the attached resistor can only control the extracellular impedance and never causes forced stimulation; we call this technique transcranial extracellular impedance control (tEIC). We conducted a behavioral experiment to evaluate tEIC and found evidence that it had real-time enhancement and depression effects on EEGs and a real-time facilitation effect on reaction times. Thus, tEIC could be another technique to modulate behavioral performance.
Theory of lifetime of exciton incoherently created below its resonance frequency by inelastic scattering
Motoaki Bamba,Shuji Wakaiki,Hideki Ichida,Kohji Mizoguchi,DaeGwi Kim,Masaaki Nakayama,Yasuo Kanematsu
Physics , 2014, DOI: 10.1103/PhysRevB.91.235205
Abstract: When an exciton in semiconductor is scattered and its energy is decreased far below the resonance energy of the bare exciton state, it has been considered that an exciton-polariton is created immediately by the scattering process, because there is no exciton level at that energy. However, according to the recent time-resolved measurements of P emission originating from inelastic exciton-exciton scattering, it looks rather natural to consider that the exciton-polariton is created in a finite time scale which is restricted by a coherence volume of the exciton after the scattering. In this interpretation, the exciton remains in this time scale far below its resonance energy as a transient state in a series of processes. We propose an expression of the P-emission lifetime depending on the coherence volume of the scattered excitons through the conversion process from them to the polaritons. The coherence volume of the scattered excitons appears in the calculation of the inelastic scattering process on the assumption of a finite coherence volume of the bottleneck excitons.Time-resolved optical-gain measurements could be a way for investigating the validity of our interpretation.
Adaptive Parallel Particle Swarm Optimization Algorithm Based on Dynamic Exchange of Control Parameters  [PDF]
Masaaki Suzuki
American Journal of Operations Research (AJOR) , 2016, DOI: 10.4236/ajor.2016.65037
Abstract: Updating the velocity in particle swarm optimization (PSO) consists of three terms: the inertia term, the cognitive term and the social term. The balance of these terms determines the balance of the global and local search abilities, and therefore the performance of PSO. In this work, an adaptive parallel PSO algorithm, which is based on the dynamic exchange of control parameters between adjacent swarms, has been developed. The proposed PSO algorithm enables us to adaptively optimize inertia factors, learning factors and swarm activity. By performing simulations of a search for the global minimum of a benchmark multimodal function, we have found that the proposed PSO successfully provides appropriate control parameter values, and thus good global optimization performance.
A Study on Flow Structure around a Bridge Beam and Behavior of Sea Water Mist  [PDF]
Masaaki Ishikawa
Open Journal of Fluid Dynamics (OJFD) , 2017, DOI: 10.4236/ojfd.2017.73022
Abstract: Okinawa in the subtropical islands enclosed in the ocean has a problem that corrosion of structures progresses quickly because of high temperature, high humidity and adhesion of sea-water mists flying from sea. Author is interested in corrosion of bridge made of weatherability steel. Therefore, it needs to investigate the flow structure around bridge beams and behavior of sea-water mist (droplet). In this paper, flow visualization and PIV are attempted to understand the flow structures around bridge beams and, furthermore, numerical approach of motion of droplets is attempted to understand the collision of sea-water mists on the bridge wall.
Methylglyoxal (MG) and Cerebro-Renal Interaction: Does Long-Term Orally Administered MG Cause Cognitive Impairment in Normal Sprague-Dawley Rats?
Kimio Watanabe,Kana Okada,Ryoji Fukabori,Yoshimitsu Hayashi,Koichi Asahi,Hiroyuki Terawaki,Kazuto Kobayashi,Tsuyoshi Watanabe,Masaaki Nakayama
Toxins , 2014, DOI: 10.3390/toxins6010254
Abstract: Methylglyoxal (MG), one of the uremic toxins, is a highly reactive alpha-dicarbonyl compound. Recent clinical studies have demonstrated the close associations of cognitive impairment (CI) with plasma MG levels and presence of kidney dysfunction. Therefore, the present study aims to examine whether MG is a direct causative substance for CI development. Eight-week-old male Sprague-Dawley (SD) rats were divided into two groups: control ( n = 9) and MG group ( n = 10; 0.5% MG in drinking water), and fed a normal diet for 12 months. Cognitive function was evaluated by two behavioral tests (object exploration test and radial-arm maze test) in early (4–6 months of age) and late phase (7–12 months of age). Serum MG was significantly elevated in the MG group (495.8 ± 38.1 vs. 244.8 ± 28.2 nM; p < 0.001) at the end of study. The groups did not differ in cognitive function during the course of study. No time-course differences were found in oxidative stress markers between the two groups, while, antioxidants such as glutathione peroxidase and superoxide dismutase activities were significantly increased in the MG group compared to the control. Long-term MG administration to rats with normal kidney function did not cause CI. A counter-balanced activation of the systemic anti-oxidant system may offset the toxicity of MG in this model. Pathogenetic significance of MG for CI requires further investigation.
Histopathological Examination and Literature Review of Orthokeratinized Odontogenic Cyst  [PDF]
Hirotoshi Iwai, Takehiro Suzuki, Tomoko Suzuki, Juri Muramori, Hiroyuki Seto, Mitsuko Nakayama, Tadahiko Utsunomiya, Masaaki Suemitsu, Kayo Kuyama, Satoshi Hirayama
Open Journal of Stomatology (OJST) , 2019, DOI: 10.4236/ojst.2019.95013
Abstract: Background: With transitions in the disease concept of orthokeratinized odontogenic cyst (OOC), the pathogenesis and etiology have not been sufficiently elucidated. Objectives: OOC cases were reclassified and observed to understand the clinico-histopathological characteristics. In addition, literature review of OOC was performed to better organize the pathology. Materials and methods: Subjects with jawbone cysts lined by keratinized stratified squamous epithelium from 2005 to 2018 were reclassified, and clinico-histopathological findings were analyzed. Previous reports of OOC/orthokeratinized-type odontogenic keratocyst (OKC) from 1980 to 2019 were organized. Results: Five cases of OOC were diagnosed, representing 2.1% of odontogenic developmental cysts (total, 239 cases). Mean age was 37.6 years, with a female predominance. The mandibular molar area was the frequent site, and all cysts were solitary. Sixty percent involved an impacted tooth. Mean maximum diameter of the cyst was 2.2 cm. Histopathologically, 4 cases were unilocular, and partial palisading of the basal layer and scattered epithelial islands were observed in 2 cases each and formation of daughter cysts was noted in 3 cases. Previous papers described that most were unilocular and related to impacted teeth. Mean age ranged between 20 and 40 years, and the mandibular molar region was dominant. Recurrence rates were low. Conclusion: OOC shows a different biological attitude to OKC and is closer to dentigerous cyst. Meanwhile, OOC shows a similar histology of epidermoid cysts accompanying the granular layer. We thus surmised that OCC represents an independent concept as an odontogenic developmental cyst.
Association between vitamin D receptor gene haplotypes and chronic periodontitis among Japanese men
Mariko Naito, Koichi Miyaki, Toru Naito, Ling Zhang, Keika Hoshi, Asako Hara, Katsunori Masaki, Shugo Tohyama, Masaaki Muramatsu, Nobuyuki Hamajima, Takeo Nakayama
International Journal of Medical Sciences , 2007,
Abstract: Background: The vitamin D receptor (VDR) is involved in a variety of biological processes, such as bone metabolism and modulation of the immune response. Recent findings suggest that the pathway involving bone mineral density-mediated effects is important for the development of periodontitis, but their effects of combined VDR gene polymorphisms have not been confirmed on periodontitis. We assessed the relationship between ApaI, BsmI, and FokI VDR polymorphisms and the risk of severe chronic periodontitis among Japanese adult men. Materials and Methods: In a cross-sectional study, we examined 97 unrelated healthy Japanese men (mean age: 45.6 years, range: 22-59). A clinical examination was performed at a worksite health checkup, and information was obtained using a self-reported questionnaire. DNA was extracted from whole blood, and the VDR ApaI, BsmI, and FokI polymorphisms were genotyped using polymerase chain reaction. Results: F-carriers of FokI VDR polymorphisms were less likely to develop severe chronic periodontitis than non-F-carriers (p = 0.09). The ApaI and BsmI VDR polymorphisms did not show significant differences in the alleles or genotypes between the subjects with or without severe chronic periodontitis. The haplotype analysis of the three combined VDR polymorphisms revealed that the Abf homozygote had a notably higher prevalence of severe chronic periodontitis than the others, and adjustments for age, smoking status, number of teeth present, and prevalence of diabetes did not change this association (OR = 7.5; 95% CI = 1.6-34.4; p = 0.01). Conclusion: The VDR haplotype constructed from the ApaI, BsmI, and FokI polymorphisms is related to the risk of severe chronic periodontitis in Japanese men.
Skin Autofluorescence Is Associated with the Progression of Chronic Kidney Disease: A Prospective Observational Study
Kenichi Tanaka, Masaaki Nakayama, Makoto Kanno, Hiroshi Kimura, Kimio Watanabe, Yoshihiro Tani, Yuki Kusano, Hodaka Suzuki, Yoshimitsu Hayashi, Koichi Asahi, Keiji Sato, Toshio Miyata, Tsuyoshi Watanabe
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0083799
Abstract: Background Advanced glycation end product (AGE) accumulation is thought to be a measure of cumulative metabolic stress that has been reported to independently predict cardiovascular disease in diabetes and renal failure. The aim of this study was to evaluate the association between AGE accumulation, measured as skin autofluorescence, and the progression of renal disease in pre-dialysis patients with chronic kidney disease (CKD). Methods Skin autofluorescence was measured noninvasively with an autofluorescence reader at baseline in 449 pre-dialysis patients with CKD. The primary end point was defined as a doubling of serum creatinine and/or need for dialysis. Results Thirty-three patients were lost to follow-up. Forty six patients reached the primary end point during the follow-up period (Median 39 months). Kaplan-Meier analysis showed a significantly higher risk of development of the primary end points in patients with skin autofluorescence levels above the optimal cut-off level of 2.31 arbitrary units, derived by receiver operator curve analysis. Cox regression analysis revealed that skin autofluorescence was an independent predictor of the primary end point, even after adjustment for age, gender, smoking history, diabetes, estimated glomerular filtration rate and proteinuria (adjusted hazard ratio 2.58, P = 0.004). Conclusions Tissue accumulation of AGEs, measured as skin autofluorescence, is a strong and independent predictor of progression of CKD. Skin autofluorescence may be useful for risk stratification in this group of patients; further studies should clarify whether AGE accumulation could be one of the therapeutic targets to improve the prognosis of CKD.
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