47 results on '"KO NAKAMURA"'
Search Results
2. Information Leakage Threats for Cryptographic Devices Using IEMI and EM Emission
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Hideaki Sone, Ko Nakamura, Takaaki Mizuki, and Yu-ichi Hayashi
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Computer science ,microprocessor chips ,intentional electromagnetic interference (IEMI) ,EM leakage ,Encryption ,Cryptography ,Hardware_PERFORMANCEANDRELIABILITY ,02 engineering and technology ,injection timing estimation method ,Electromagnetic interference ,Transient analysis ,fault analysis method ,intentional electromagnetic interference ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,characteristic fluctuation detection ,realistic secret information analysis method ,Fault analysis ,Timing ,Electrical and Electronic Engineering ,fault-injection timing ,Leakage (electronics) ,Clocks ,cryptography ,Differential fault analysis ,information leakage threat ,business.industry ,fault analysis ,Circuit faults ,020206 networking & telecommunications ,Fault injection ,fault diagnosis ,Condensed Matter Physics ,on-chip fault-injection circuit ,cryptographic devices ,electromagnetic interference ,Atomic and Molecular Physics, and Optics ,IEMI ,Information leakage ,secret key analysis ,Electromagnetic (EM) information leakage ,business ,Estimation - Abstract
In this paper, we present a new information leakage threat combining intentional electromagnetic interference (IEMI) and observations of EM leakage. In previous studies, the analysis of secret key information in cryptographic modules using fault injection has led to methods whereby faults can be injected via low-voltage IEMI. However, the timing of fault injections cannot be controlled with this approach, and it is difficult to obtain faulty ciphertexts for use in secret key analysis by differential fault analysis (DFA). To overcome this problem, we propose a method for estimating the fault-injection timing by detecting characteristic fluctuations in the EM leakage from the device. As a result, it may be possible to implement a realistic secret information analysis method applicable to a wide range of devices. First, to show the feasibility of the proposed method, we describe an experiment using an on-chip fault-injection circuit that can control the injection timing. Furthermore, we apply a fault analysis method that combines the injection timing estimation method and fault injection by IEMI in a practical experimental environment. We select useful faulty ciphertexts using the proposed method, and then perform secret key analysis by DFA. Experimental results demonstrate that the secret key can be successfully analyzed.
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- 2017
3. Introduction of Feature Captured Motion illusion: The interpretation and its verification by some experimental observation
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Ko Nakamura
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business.industry ,Computer science ,Feature (computer vision) ,media_common.quotation_subject ,Illusion ,Computer vision ,Artificial intelligence ,business ,Motion (physics) ,media_common ,Interpretation (model theory) - Published
- 2017
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4. The Changing Structure of International Law on Marine Living Resources
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Ko Nakamura
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Structure (mathematical logic) ,business.industry ,Political science ,International trade ,International law ,business - Published
- 2019
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5. THE STUDY OF THE ARCHITECTURAL STYLE OF “SOAN” TEA HOUSE THROUGH THE MULTIVARIATE ANALYSES OF THE PHYSICAL QUANTITATIVE DATA OF ELEMENTS
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Yuta Ito, Ko Nakamura, and Kengo Kuma
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Engineering ,Multivariate analysis ,Anthropology ,business.industry ,business ,Composition (language) ,Architectural style - Published
- 2016
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6. A METHOD TO DISCRIMINATE OCCLUDING EDGES RELATED TO SPATIAL DIVISION
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Kaoru Yamaoka, Ko Nakamura, and Kengo Kuma
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Computer science ,business.industry ,Computer vision ,Artificial intelligence ,Division (mathematics) ,business - Published
- 2015
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7. A STUDY ON THE SYSTEM OF HAWKER'S ASSEMBLY AND SPONTANEOUS MARKET FORCE FROM MALAYSIA'S COFFEESHOP AND SINGAPORE'S HAWKER CENTRE
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Nobuaki Furuya and Ko Nakamura
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Engineering ,Coffee shop ,business.industry ,Advertising ,business - Abstract
The Coffee Shop called Kopi Tiam in Malaysia is an interesting system of eating house as assembly of hawkers. The independent hawkers with each special meal are assembled by the shop's owner, and the owner provides drink stall and tables for eat. It is similar to Hawker Centre in Singapore or modern food court, but It seems to became a spontaneous system to sustain the quality of foods. The Coffee Shop in Malaysia is analyzed by compared with Hawker Centre in Singapore to clarify the system and know a type of the plan.
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- 2011
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8. Ferroelectric random access memory with high electric properties and high production yield realized by employing an AlOx underlying layer of Pt bottom electrode for a La-doped lead zirconate titanate capacitor
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Hideshi Yamaguchi, Kenji Nomura, Yukinobu Hikosaka, Takashi Eshita, Soichiro Ozawa, Hitoshi Saito, Yuji Kataoka, Manabu Kojima, Kazuaki Takai, Wensheng Wang, Ko Nakamura, Junichi Watanabe, and Satoru Mihara
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010302 applied physics ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Doping ,General Engineering ,General Physics and Astronomy ,Lead zirconate titanate ,01 natural sciences ,Ferroelectricity ,law.invention ,chemistry.chemical_compound ,Capacitor ,chemistry ,law ,0103 physical sciences ,Electrode ,Surface roughness ,Optoelectronics ,business ,Polarization (electrochemistry) ,Layer (electronics) - Abstract
Although ferroelectric random access memory (FRAM) has superior electric properties, its downside is that it has a relatively larger cell area in comparison other non-volatile memories. We tried to apply TiOx, and AlOx to an underlying layer (TiOx-UL, AlOx-UL) instead of our previously used Ti underlying layer (Ti-UL) for the La-doped lead zirconate titanate (PLZT) capacitor to obtain a high polarization value aiming to a lowering cell area. The failed bit ratio of the FRAM with TiOx-UL was found to be higher than that with AlOx-UL even though polarization values of the PLZT capacitor with both underlying layers are almost the same and much higher than that with Ti-UL. It is strongly suggested that the imprint induced in PLZT by charged defect is a main cause of bit failure by fail-bit analysis. X-ray diffraction and atomic force microscopy observations shows that charged defect density in PLZT over TiOx-UL is possibly higher than that in PLZT over AlOx-UL due to surface roughness of underlying layers.
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- 2018
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9. Development of highly reliable ferroelectric random access memory and its Internet of Things applications
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Kenji Nomura, Yukinobu Hikosaka, Ko Nakamura, Yuji Kataoka, Hideshi Yamaguchi, Wensheng Wang, Hitoshi Saito, Manabu Kojima, Satoru Mihara, and Takashi Eshita
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010302 applied physics ,Random access memory ,Hardware_MEMORYSTRUCTURES ,Physics and Astronomy (miscellaneous) ,Multimedia ,business.industry ,Reliability (computer networking) ,General Engineering ,General Physics and Astronomy ,02 engineering and technology ,Energy consumption ,021001 nanoscience & nanotechnology ,computer.software_genre ,01 natural sciences ,Ferroelectricity ,Hardware_GENERAL ,0103 physical sciences ,0210 nano-technology ,Internet of Things ,business ,computer ,Edge computing ,Random access - Abstract
Ferroelectric random access memory (FRAM) has been commercialized for about 20 years and its reliability has been well proven all over the world. In the recent Internet of Things (IoT) era, it also plays important roles to particularly in edge computing because of its high writing speed, high rewriting endurance, and low writing energy consumption. We review the history of semiconductor memories using ferroelectrics and overview the progresses of the new ferroelectrics and promising ferroelectric applications in the future.
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- 2018
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10. HAWKER'S BEHAVIOR ON THE SPONTANEOUS ORDER AS 'LOCAL CODE' IN BANGKOK'S CHINATOWN
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Ko Nakamura and Nobuaki Furuya
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Engineering ,Chinatown ,business.industry ,Law ,Urban design ,Advertising ,business ,Spontaneous order ,Code (semiotics) - Abstract
There is an “Illegality” on people's activity like hawkers on street. In that case, the law lose effect and people's unspoken agreement regulate their activity instead of the law. It can be considered coexistence of the spontaneous order as “Local code” and free behavior without restriction from the law. With that background, Hawker's “Illegality” and their behavior In Bangkok's Chinatown were analyzed on following 3 aims.1. To show the effective utilization through a classification of eating activities on the street as an urban public space.2. To consider the “Illegality” for urban design as a new aspect of architectural planning.3. To discover the “Local code” developed from hawker's relations between themselves as a making spontaneous rules with their unspoken agreement.
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- 2010
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11. Urinary Excretion of Creatol, an In Vivo Biomarker of Hydroxyl Radical, in Patients with Chronic Renal Failure
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Hikaru Koide, Mitsuharu Narita, Koji Nakano, Tomoe Fujisawa, Yasutsugu Fukunaga, Hiroshi Nihei, Tsutomu Sanaka, Kazuharu Ienaga, Kazumasa Aoyagi, Yasuhiko Tomino, and Ko Nakamura
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Adult ,Male ,Nephrology ,medicine.medical_specialty ,Urinary system ,chemical and pharmacologic phenomena ,Methylguanidine ,Urine ,Critical Care and Intensive Care Medicine ,medicine.disease_cause ,Severity of Illness Index ,Excretion ,chemistry.chemical_compound ,Japan ,In vivo ,Internal medicine ,medicine ,Humans ,Chromatography, High Pressure Liquid ,Aged ,Aged, 80 and over ,Creatinine ,Hydroxyl Radical ,business.industry ,hemic and immune systems ,General Medicine ,Middle Aged ,Circadian Rhythm ,Oxidative Stress ,CTL ,Endocrinology ,chemistry ,Kidney Failure, Chronic ,Regression Analysis ,Female ,business ,Biomarkers ,Oxidative stress - Abstract
Creatol (CTL) is a hydroxyl radical adduct of creatinine (Cr). The serum methylguanidine (MG) level and the MG/Cr molar ratio are reported to be biomarkers for oxidative stress. The aim of this study was to examine whether urinary excretion of CTL, another oxidative stress-related marker, is increased in patients with chronic renal failure (CRF). One hundred twenty-four non-dialyzed patients with chronic renal failure (serum Cr level, 1.3-10.0 mg/dL) were recruited from our hospitals. Urine and serum levels of CTL and MG were determined by high-performance liquid chromatography with the use of 9, 10- phenanthrenequinone as a fluorogenic reagent. The CTL/Cr and (CTL+MG)/Cr molar ratios in spot urine samples were also compared with those in 24-h urine samples. The urinary CTL/Cr and (CTL+MG)/Cr molar ratios increased with decreases in Cr clearance in patients with CRF. Correlations between serum and spot urine (CTL+MG)/Cr and between serum and spot urine CTL/Cr were quite similar to those in 24-h urine samples. CTL/Cr and (CTL+MG)/Cr molar ratios in both 24-h urine and spot urine samples appear to be useful indices of the severity of CRF.
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- 2007
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12. Method for estimating fault injection time on cryptographic devices from EM leakage
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Hideaki Sone, Ko Nakamura, Yu-ichi Hayashi, Naofumi Homma, Takaaki Mizuki, and Takafumi Aoki
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Engineering ,Differential fault analysis ,business.industry ,Hardware_PERFORMANCEANDRELIABILITY ,Fault injection ,Encryption ,Electromagnetic interference ,Fault indicator ,Stuck-at fault ,Fault coverage ,Electronic engineering ,Waveform ,business ,Simulation - Abstract
The existing intentional electromagnetic interference (IEMI) fault injection method based on continuous sinusoidal wave has a difficulty in injecting faults at a specific operation or time. This means that the obtained faulty outputs do not always satisfy a specific condition (e.g., time or number of error bytes) for performing fault analysis such as differential fault analysis (DFA). This paper presents a method for estimating the timing of fault occurrences caused by the above IEMI-based method, which make it possible to examine if an obtained faulty output is available for fault analysis. The idea of this method is to observe side-channel information such as EM leakage and estimate fault injection time from the detection of a characteristic change in the obtained waveform. To validate this method, we performed an IEMI fault injection experiment on actual cryptographic hardware (a side-channel attack standard evaluation board). From the obtained faulty encryption outputs and waveforms, we confirm that the fault injection time estimated by back-calculation of faulty outputs corresponded to that obtained by waveform analysis. We also demonstrate the validity of several non-invasive observation techniques for obtaining waveforms.
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- 2015
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13. A Triple-Protection Structured COB FRAM with 1.2-V Operation and 1017-Cycle Endurance
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Mitsuharu Nakazawa, Masaki Okuda, Kazuaki Takai, Hitoshi Saito, Satoru Mihara, Masato Matsumiya, Takashi Eshita, Tomoyuki Hori, Yukinobu Hikosaka, Ko Nakamura, Makoto Hamada, Shoichiro Kawashima, Soichiro Ozawa, Noboru Kosugi, Wensheng Wang, Tatsuya Sugimachi, and Naoya Sashida
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Materials science ,business.industry ,Electrical engineering ,Ferroelectricity ,Ferroelectric capacitor ,law.invention ,Non-volatile memory ,Capacitor ,law ,Electrode ,Ferroelectric RAM ,Optoelectronics ,Degradation (geology) ,business ,Voltage - Abstract
We have developed a ferroelectric RAM (FRAM) with a low operation voltage of 1.2 V and a high switching endurance up to 1017 cycles. Our newly developed tripleprotection structured cell array, has constructed without an additional mask step, effectively protects 0.4-μm2 ferroelectric capacitors from hydrogen and moisture degradation. We have designed our capacitor-over-bit-line (COB) structure to have a small cell size of 0.5 μm2.
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- 2015
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14. Crosslines, Fluorophores in the AGE-Related Cross-Linked Proteins
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Yoshitaka Nakazawa, Yasutsugu Fukunaga, Toshikazu Hochi, Kazuharu Ienaga, Koji Nakano, Hideharu Kakita, and Ko Nakamura
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Maillard reaction ,symbols.namesake ,Biochemistry ,Dialysis related amyloidosis ,business.industry ,Age related ,symbols ,Medicine ,business ,RENAL DISORDERS - Abstract
We can summarize our results as follows: (1) A pair of fluorescent crosslines were isolated from the Maillard reaction mixture; (2) AGE-proteins contained crossline-like structures, and (3) crossline-like immunoreactivities were accumulated in renal tissues of diabetic rats. From these results we concluded that fluorophores in AGE proteins have crossline-like structures and we had the first indication that XLs could be markers for renal disorders.
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- 2015
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15. Nitric Oxide-Mediated Vasodilatory Effect Of Atrial Natriuretic Peptide In Forearm Vessels Of Healthy Humans
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Takashi Sugamori, Yoko Ohta, Shuzo Ohata, Nobuhiro Kodani, Harumi Katoh, Hiromi Shimizu, Takeshi Sakane, Yoshitsugu Kunizawa, Yutaka Ishibashi, Toshio Shimada, Yo Murakami, Nobuyuki Takahashi, Shin-ichi Inoue, and Ko Nakamura
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Adult ,Male ,medicine.medical_specialty ,Nitric Oxide Synthase Type III ,Endothelium ,Physiology ,Vasodilation ,Nitric Oxide ,Statistics, Nonparametric ,Nitric oxide ,chemistry.chemical_compound ,Atrial natriuretic peptide ,Forearm ,Physiology (medical) ,Internal medicine ,Renin–angiotensin system ,medicine ,Humans ,Enzyme Inhibitors ,Pharmacology ,Analysis of Variance ,Dose-Response Relationship, Drug ,business.industry ,Angiotensin II ,Middle Aged ,body regions ,medicine.anatomical_structure ,Endocrinology ,chemistry ,cardiovascular system ,Female ,Nitric Oxide Synthase ,business ,Atrial Natriuretic Factor ,hormones, hormone substitutes, and hormone antagonists ,circulatory and respiratory physiology - Abstract
1. The aim of the present study was to determine whether the vasorelaxant effect of atrial natriuretic peptide (ANP) is, in part, endothelium dependent in humans. 2. We used veno-occlusive plethysmography to measure forearm blood flow (FBF) during intra-arterial infusions of ANP (4, 8, 16, 32 pmol/min per dL forearm tissue volume) before and after the inhibition of nitric oxide (NO) synthesis by N(G)-monomethyl-L-arginine (L-NMMA; 100 micromol) in seven normal healthy subjects. 3. Atrial natriuretic peptide caused a dose-dependent increase in FBF both before and after L-NMMA and significantly reduced the plasma concentration of angiotensin (Ang) II. Administration of L-NMMA significantly diminished the increase in FBF in response to ANP infusion (P < 0.05). 4. These results suggest that the forearm vasodilative response to ANP is modulated, in part, by an endothelium-derived NO-mediated mechanism associated with a decrease in AngII caused by ANP.
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- 2002
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16. Impaired Exercise-Induced Vasodilatation in Chronic Atrial Fibrillation. Role of Endothelium-Derived Nitric Oxide
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Shin-ichi Inoue, Yo Murakami, Toshio Shimada, Takashi Sugamori, Nobuyuki Takahashi, Ko Nakamura, Yoko Ohta, Shuzo Ohata, Harumi Katoh, Hiromi Shimizu, Yutaka Ishibashi, and Takeshi Sakane
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Endothelium ,business.industry ,medicine.medical_treatment ,Hemodynamics ,Atrial fibrillation ,General Medicine ,medicine.disease ,Cardioversion ,body regions ,medicine.anatomical_structure ,Blood pressure ,Anesthesia ,Heart rate ,medicine ,Omega-N-Methylarginine ,Sinus rhythm ,Cardiology and Cardiovascular Medicine ,business - Abstract
Exercise capacity is often reduced in patients with atrial fibrillation (AF), but very few studies have focused on changes in endothelial function as a potential mechanism for the exercise limitation. The present study used using venous occlusion plethysmography to investigate whether nitric oxide (NO)-mediated vasodilatation is attenuated during exercise in patients with AF by measuring forearm blood flow (FBF) in 10 patients at rest and immediately after 2 levels of rhythmic handgrip exercise, before and after inhibition of NO synthesis with N(G)-monomethyl-L-arginine (L-NMMA, 100 micromol). The measurements were repeated 1 day after restoration of sinus rhythm by cardioversion. FBF responses to graded doses of acetylcholine (ACh) were also observed before and after cardioversion. Heart rate decreased after cardioversion, but blood pressure did not change. FBF at rest was not affected by cardioversion, but at the highest level of exercise it increased from 28.4+/-2.3 ml x min(-1) x dl(-1) before to 39.4+/-3.2 ml x min(-1) x dl(-1) after cardioversion (p
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- 2002
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17. Increased Nitric Oxide in Proportion to the Severity of Heart Failure in Patients With Dilated Cardiomyopathy. Close Correlation of Tumor Necrosis Factor-.ALPHA. With Systemic and Local Production of Nitric Oxide
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Shin-ichi Inoue, Yoshitsugu Kunizawa, Harumi Katoh, Hiromi Shimizu, Yutaka Ishibashi, Nobuyuki Takahashi, Yoko Ohta, Ko Nakamura, Shuzo Ohata, Takeshi Sakane, Michio Hashimoto, Nobuyuki Oyake, Takashi Sugamori, Toshio Shimada, and Yo Murakami
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medicine.medical_specialty ,Heart disease ,business.industry ,Dilated cardiomyopathy ,General Medicine ,Brain natriuretic peptide ,medicine.disease ,Proinflammatory cytokine ,Nitric oxide ,chemistry.chemical_compound ,chemistry ,Heart failure ,Internal medicine ,cardiovascular system ,medicine ,Cardiology ,Omega-N-Methylarginine ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,business ,Vasoconstriction - Abstract
Recent studies have demonstrated that proinflammatory cytokines induce large amounts of nitric oxide (NO) and that the amount increases in patients with congestive heart failure (CHF). There are, however, few reports regarding the relationships between NO production, cytokines and the severity of heart failure, so the plasma concentrations of nitrite and nitrate (NOx), tumor necrosis factor-α (TNF-α) and brain natriuretic peptide (BNP) were measured in 43 patients with CHF caused by dilated cardiomyopathy and 26 age- and sex-matched normal control subjects. Forearm blood flow (FBF) was measured using plethysmography during infusions of acetylcholine and nitroglycerin and after the administration of the NO synthesis inhibitor L-NMMA (NG-monomethyl-L-arginine). Plasma concentrations of both NOx and TNF-α were significantly higher in the patient group than in the control group (p
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- 2002
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18. Development of ferroelectric RAM (FRAM) for mass production
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Hideshi Yamaguchi, Satoru Mihara, Ko Nakamura, Shoichiro Kawashima, Wensheng Wang, Kenji Nomura, Inoue Kenichi, Takashi Eshita, Yukinobu Hikosaka, and Hitoshi Saito
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Hardware_MEMORYSTRUCTURES ,Materials science ,Fabrication ,business.industry ,Amplifier ,Ferroelectricity ,Ferroelectric capacitor ,law.invention ,Non-volatile memory ,Capacitor ,Hardware_GENERAL ,law ,Ferroelectric RAM ,Hardware_INTEGRATEDCIRCUITS ,Optoelectronics ,business ,Voltage - Abstract
We have developed ferroelectric capacitor fabrication technique and a new sensing amplifier circuit to realize low-voltage and high-density FRAM. Improvement of IrO, top electrode near the ferroelectric interface successively lowers operation voltage. And our developed “Dual Reference Sensing Amplifier” enables to commercialize highly-reliable FRAM with memory density of 4Mb or larger.
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- 2014
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19. Crossline levels in serum and erythrocyte membrane proteins from patients with diabetic nephropathy
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Mitsuhiro Fujii, Ko Nakamura, Motoharu Kondo, Goji Hasegawa, Fumiaki Kimura, Hiroshi Obayashi, Naoto Nakamura, Hirofumi Shigeta, Shin-ichiro Aoki, Kazuharu Ienaga, and Akira Moriwaki
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Male ,medicine.medical_specialty ,Glycosylation ,Endocrinology, Diabetes and Metabolism ,Enzyme-Linked Immunosorbent Assay ,Nephropathy ,Diabetic nephropathy ,chemistry.chemical_compound ,Endocrinology ,Reference Values ,Glycation ,Diabetes mellitus ,Internal medicine ,Glycated Serum Proteins ,Blood plasma ,Internal Medicine ,medicine ,Humans ,Diabetic Nephropathies ,Aged ,Glycoproteins ,Analysis of Variance ,Creatinine ,Proteinuria ,business.industry ,Erythrocyte Membrane ,Membrane Proteins ,Blood Proteins ,General Medicine ,Middle Aged ,medicine.disease ,Red blood cell ,Diabetes Mellitus, Type 1 ,medicine.anatomical_structure ,Diabetes Mellitus, Type 2 ,chemistry ,Female ,medicine.symptom ,business - Abstract
Crossline is one of the structurally defined adducts of advanced glycation endproducts (AGEs) which has both a crosslink and fluorescence similar to AGE-protein in vivo. Crossline was measured in serum and erythrocyte membrane proteins (EMP) from 52 type 2 diabetic patients using a specific enzyme-linked immunosorbent assay system. Serum and EMP crossline levels in the diabetic patients were significantly higher than those in normal control. The patients with advanced diabetic nephropathy (serum creatinine levels of more than 1.2 mg/dl) had markedly elevated serum crossline levels compared to those with moderate diabetic nephropathy (clinical proteinuria) (180. 7+/-51.7 vs. 71.8+/-18.4 pmol/ml; P0.01). On the other hand, there were no significant differences in EMP crossline levels between the two. EMP crossline levels in the patients with moderate diabetic nephropathy (8.8+/-2.9 pmol/mg protein) and those with advanced diabetic nephropathy (9.7+/-3.0 pmol/mg protein) were significantly higher than those without clinical proteinuria (6.4+/-1.9 pmol/mg protein; P0.01). The present study demonstrated that EMP crossline levels were associated with the presence of nephropathy in patients with type 2 diabetes mellitus. Serum crossline levels were significantly influenced by remaining renal function. The measurement of crossline from a blood sample could provide us with important information for the study of clinical evaluation and pathogenesis of diabetic complications.
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- 2000
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20. Peak negative myocardial velocity gradient in early diastole as a noninvasive indicator of left ventricular diastolic function
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Yoshito Shimizu, Masaaki Uematsu, Hiromi Shimizu, Ko Nakamura, Masakazu Yamagishi, and Kunio Miyatake
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medicine.medical_specialty ,medicine.diagnostic_test ,business.industry ,Diastole ,Hemodynamics ,Dilated cardiomyopathy ,Doppler echocardiography ,medicine.disease ,Doppler imaging ,Hypertensive heart disease ,Preload ,Internal medicine ,Heart failure ,medicine ,Cardiology ,business ,Cardiology and Cardiovascular Medicine - Abstract
Objectives. We sought to assess the clinical significance of peak negative myocardial velocity gradient (MVG) in early diastole as a noninvasive indicator of left ventricular (LV) diastolic function. Background. Peak systolic MVG has been shown useful for the quantitative assessment of regional wall motion abnormalities, but limited data exist regarding the diastolic MVG as an indicator of LV diastolic function. Methods. Peak negative MVG was obtained from M-mode tissue Doppler imaging (TDI) in 43 subjects with or without impairment of systolic and diastolic performance: 12 normal subjects, 12 patients with hypertensive heart disease (HHD) with normal systolic performance and 19 patients with dilated cardiomyopathy (DCM), and was compared with standard Doppler transmitral flow velocity indices. In a subgroup of 30 patients, effects of preload increase on these indices were assessed by performing passive leg lifting. In an additional 11 patients with congestive heart failure at the initial examination, the measurements were repeated after 26 ± 16 days of volume-reducing therapy. Results. Peak negative MVG was significantly depressed both in HHD (−3.9 ± 1.3/s, p Conclusions. Peak negative MVG derived from TDI may be a noninvasive indicator of LV diastolic function that is less affected by preload alterations than the transmitral flow velocity indices, and thereby could be used for the follow-up of patients with nonischemic LV dysfunction presenting congestive heart failure.
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- 1998
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21. [Untitled]
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Ko Nakamura, Guican Zhang, Takanori Tsukada, Yoshikazu Masuda, Masaaki Uematsu, Yoshio Yasumura, Satoshi Nakatani, Masakazu Yamagishi, Kunio Miyatake, and Norio Tanaka
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Boundary detection ,Asynergy ,Ejection fraction ,Ventricular function ,business.industry ,Medicine ,Hemodynamics ,Stroke volume ,Wall motion ,business ,Nuclear medicine ,Cardiac imaging - Abstract
It is still unclear whether echocardiography with an automated boundary detection technique (ABD) can accurately determine the left ventricular (LV) volume and function particularly in the presence of LV wall asynergy. We intended to re-evaluate the reliability and application of the ABD, which was based on the acoustic quantification technique (Sonos 2500, Hewlett Packard) for the LV volume measurement in patients without or with LV wall asynergy. A total of 80 patients (mean age 56 years) who underwent left ventriculography (LVG) were divided into two groups. The group A consisted of 29 patients with normal LV wall motion and the group B consisted of 51 patients with generalized or regional LV wall motion abnormality. In group A patients, the LV end-diastolic volume (LVEDV) was 96 ± 25 ml by ABD and 112 ± 33 ml by LVG and those of LV end-systolic volume (LVESV) were 44 ± 14 ml by ABD and 48 ± 17 ml by LVG, thus resulting in the underestimation of LV volume by 12% in average. Under these conditions, the LV ejection fraction (LVEF) by ABD, 54 ± 8%, correlated well with that by LVG, 58 ± 7%. Although underestimation of LV volume by 17% in average also occurred in groups B (N.S.), LVEF was found to correlate well with that by LVG; 27 ± 8% vs 30 ± 11% (r=0.87, SEE=3.1%) for 21 patients with the generalized LV asynergy; 39 ± 10% vs 39 ± 12% (r=0.86. SEE=3.3%) for 30 patients with the regional LV asynergy. These results demonstrate the feasibility of the ABD in determining the LVEF, although underestimation can occur in measuring the absolute LV volume in patients with or without LV asynergy.
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- 1998
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22. Advanced Glycation End Products Induce Expression of Vascular Endothelial Growth Factor by Retinal Müller Cells
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Hiroshi Sawa, Yoshihiro Kitagawa, Masakazu Ogata, Koji Nakano, Hiroshi Obayashi, Chizuko Hirata, Ko Nakamura, Motoharu Kondo, Kazuharu Ienaga, Goji Hasegawa, Tsunehiko Ikeda, Hirofumi Shigeta, and Naoto Nakamura
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Glycation End Products, Advanced ,Vascular Endothelial Growth Factor A ,medicine.medical_specialty ,genetic structures ,medicine.medical_treatment ,Biophysics ,Gene Expression ,Enzyme-Linked Immunosorbent Assay ,Vitrectomy ,Endothelial Growth Factors ,Polymerase Chain Reaction ,Biochemistry ,Retina ,Neovascularization ,chemistry.chemical_compound ,Glycation ,Internal medicine ,Diabetes mellitus ,medicine ,Humans ,In patient ,RNA, Messenger ,Molecular Biology ,Cells, Cultured ,Aged ,Lymphokines ,Diabetic Retinopathy ,Retinal Muller Cells ,Vascular Endothelial Growth Factors ,business.industry ,RNA-Directed DNA Polymerase ,General Medicine ,Cell Biology ,Diabetic retinopathy ,Middle Aged ,medicine.disease ,eye diseases ,Vitreous Body ,Vascular endothelial growth factor ,Ophthalmology ,Vascular endothelial growth factor A ,Endocrinology ,chemistry ,sense organs ,medicine.symptom ,business - Abstract
Recent studies have suggested that advanced glycation end products (AGEs) are involved in the development of diabetic complications. To assess the pathogenic role of AGEs and vascular endothelial growth factor (VEGF) in the development of retinal neovascularization in diabetic retinopathy, we investigated the effect of AGEs on induction of VEGF by retinal Muller cells and measured AGE and VEGF concentrations in the vitreous of patients with proliferative diabetic retinopathy (PDR) and nondiabetic patients. The expression of VEGF mRNA and the production of VEGF protein by cultured Muller cells were enhanced by the presence of AGEs. The vitreous concentrations of AGEs and VEGF were both elevated in patients with PDR compared with patients without diabetes (P < 0.01). There was a moderate positive correlation between the levels of crossline and VEGF (r=0.698, P < 0.01). Elevation of AGEs in the vitreous may promote intraocular neovascularization in diabetic retinopathy through production of VEGF from Muller cells.
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- 1997
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23. Changes in Serum Levels of Creatol and Methylguanidine in Renal Injury Induced by Lipid Peroxide Produced by Vitamin E Deficiency and GSH Depletion in Rats
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Ko Nakamura, Kiyokazu Hagiwara, Tomoe Watanabe, Kazuharu Ienaga, Hisashi Ozasa, and Yasutsugu Fukunaga
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Lipid Peroxides ,medicine.medical_specialty ,Metabolite ,medicine.medical_treatment ,Renal function ,Methylguanidine ,Kidney ,Blood Urea Nitrogen ,Lipofuscin ,chemistry.chemical_compound ,Internal medicine ,medicine ,Animals ,Vitamin E ,Vitamin E Deficiency ,Rats, Wistar ,Buthionine Sulfoximine ,Creatinine ,L-Lactate Dehydrogenase ,Lipid peroxide ,business.industry ,Kidney metabolism ,General Medicine ,Glutathione ,Acute Kidney Injury ,Rats ,Endocrinology ,chemistry ,Nephrology ,Vitamin E deficiency ,business - Abstract
A novel creatinine metabolite, creatol (5-hydroxycreatinine), is a key precursor in the synthesis of the uremic toxin methylguanidine (MG). Creatinine is converted to creatol within the mammalian body and this conversion is mediated specifically by hydroxyl radicals. We investigated the production of creatol and MG from creatinine in rats with renal failure induced by the lipid peroxide produced as a consequence of vitamin E deficiency and depletion of the reduced form of glutathione (GSH). In addition, we examined serum levels of other guanidino compounds, namely guanidinoacetic acid (GAA) and guanidinosuccinic acid (GSA). The injury to kidneys induced by the depletion of GSH in combination with vitamin E deficiency caused markedly elevated serum levels of creatol, MG and GSA and decreased serum GAA. The molar ratio of creatol to creatinine in the serum, which should be an index of the oxygen stress mediated by hydroxyl radicals, increased with time. Therefore, the enhanced production of creatol in vitamin-E-deficient rats that have been depleted of GSH might be due to the enhanced production of oxygen radicals in this system.
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- 1997
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24. The neutrino-process and light element production
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Toshikazu Shigeyama, Ko Nakamura, Takashi Yoshida, and Toshitaka Kajino
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Physics ,business.industry ,Scientific method ,Production (economics) ,Neutrino ,Element (category theory) ,Process engineering ,business - Published
- 2011
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25. L-Gulono-γ-Lactone Oxidase Is the Enzyme Responsible for the Production of Methylguanidine in the Rat Liver
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Takako Yokozawa, Naoki Fujitsuka, Hikokichi Oura, Kyoichi Kobashi, Teruaki Akao, Ko Nakamura, and Kazuharu Ienaga
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chemistry.chemical_classification ,biology ,business.industry ,Substrate (chemistry) ,Methylation ,Ascorbic acid ,chemistry.chemical_compound ,Enzyme ,Biosynthesis ,chemistry ,Biochemistry ,Methylguanidine ,L-gulonolactone oxidase ,biology.protein ,Medicine ,business ,Guanidine - Abstract
A methylguanidine-synthesizing enzyme localized in rat liver microsomes produces methylguanidine via the intermediates creatone A and creatone B from the substrate, creatol, a substance produced from
- Published
- 1993
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26. Purification of Methylguanidine Synthase from the Rat Kidney
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Teruaki Akao, Masao Hattori, Kyoichi Kobashi, Kazuharu Ienaga, Naoki Fujitsuka, Takako Yokozawa, Ko Nakamura, and Hikokichi Oura
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Male ,Oxygenase ,Molecular Sequence Data ,Flavoprotein ,Methylguanidine ,In Vitro Techniques ,Kidney ,Microbodies ,Oxygen Consumption ,L-gulonolactone oxidase ,Animals ,Medicine ,Microbody ,Amino Acid Sequence ,Rats, Wistar ,chemistry.chemical_classification ,Oxidase test ,biology ,ATP synthase ,business.industry ,Hydrogen-Ion Concentration ,Rats ,Molecular Weight ,Enzyme ,chemistry ,Biochemistry ,Creatinine ,Oxygenases ,biology.protein ,Lysosomes ,business ,L-Gulonolactone Oxidase ,Sugar Alcohol Dehydrogenases - Abstract
Methylguanidine (MG)-synthesizing enzyme was purified from rat kidney lysosomes and peroxisomes. The enzyme was a flavoprotein with a molecular weight of about 37,000 and oxidized creatol to produce MG. The present results suggest that the reaction mechanism of this enzyme is different from that of L-gulono-gamma-lactone oxidase (EC 1.1.3.8) isolated from rat liver microsomes.
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- 1993
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27. Contents, Vol. 63, 1993
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F. Tricot, D. Krzemień, J.V. Tovar, Naoki Fujitsuka, S.C. Tiwari, F. Prospert, Takako Yokozawa, L.A. Sirwal, Antonio Soto, Marie-Paule Ramée, Kazuharu lenaga, N. Belovezhdov, R. Dell’Aquila, M.J. Richard, M. Espinosa, R. Enriquez, A. Mouneimne, Ikuko Hayashi, J. Ortuño, R. Čuiairanović, F. Pizzarelli, R. Saxena, Noriyuki Tatemichi, Q. Maggiore, M. Tanvir, E. Jansson, J. Lacueva, G.H. Malik, Francisco J. Pérez Fontán, Esmeray Acartürk, A. Dhondt, S. Nomura, Richard E. Schell, B.M. Jones, D. Castillo, D. Mittal, T. Kokawa, M.A. Waterloos, V. Stefanović, Pierre Simon, M. Esbjörnsson, Michelle Barnett, Bruno Basolo, M. Bogićević, J.C. Castaño, Kazuharu Ienaga, Giuseppe Piccoli, Chikao Yasunaga, Tomoko Yazawa, S.C. Dash, D. Cordonnier, M.S. Najar, Masaaki Takano, V. Minkova, T. Jogestrand, Caje Moniz, S.K. Agarwal, Bernard F. Jones, Ian R. Rifkin, V. Jacobs, Atsushi Aikawa, R. Vanholder, M. Rivera, M.C. Denis, P. Aljama, Toshimitsu Niwa, Rafael Bárcena, Ko Nakamura, F. Fabrizi, E. Niembro, Kyoichi Kobashi, Chiou-Chyn Lin, Tung-Po Huang, M. Altaf, R. Perez, Antonio Zea, C. Zoccali, K. Yasunaga, Tsukasa Kanazawa, G. Decaux, Lg. Burdiel, Teruaki Akao, Eiisa Menegatti, S. Saxena, Francisco Mampaso, Joanne T Marsden, Ana Gonzalo, Victor Parsons, Micheline Levy, Takashi Yasuda, Teruhiko Maeba, S.K. Pehrsson, S. Ringoir, M. Postorino, Bernard Mattlinger, J.L. Teruel, P. Benito, Chikako Shiba, Akira Hasegawa, Saime Paydas, Laure-Hélène Noël, C. Gonzalez, Shigeru Owada, G. Curatola, J.A. Ruiz, Dianne Baldwin, Masashi Ishida, Phil Tuso, Yutaka Emoto, Tomoyuki Katsuzak, S.N. Mehta, Takehiro Ohara, Dario Roccatello, A. Davenport, Ching-Yuang Lin, N. Van Landschoot, Masao Hattori, N. Veys, I.K.P. Cheng, Joaquín Ortuño, Elizabeth Ball, Hikokichi Oura, W. Van Biesen, M. Mitić, J.B. Cabezuelo, Miguel Pérez Fontán, A. Martin-Malo, B. Namias, A.R. Reshi, Makoto Sugiyama, Ana Rodríguez-Carmona, Monique Menault, Philippe Lesavre, A. Soupart, A. Shouzu, M. Nishikawa, Donald Nortman, I. Altunkova, P. Vlahović, Kenji Maeda, K. Sirajeddine, Cristiana Rollino, Sonoo Mizuiri, Jw. Naskalski, Takashi Miyazaki, L.-E. Lins, N. Clyne, Donald E. Potter, Nan Chen, Sadanobu Ozawa, G. Garcia Otero, Francisco Pombo, and R. Penninckx
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Traditional medicine ,business.industry ,Medicine ,business - Published
- 1993
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28. Comparison of Renal Effects of Creatinine, Creatol and Methylguanidine in Rats with Adenine-lnduced Chronic Renal Failure
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Hikokichi Oura, Kazuharu Ienaga, Takako Yokozawa, and Ko Nakamura
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Male ,medicine.medical_specialty ,Metabolite ,Renal function ,Methylguanidine ,Kidney Function Tests ,Renal Circulation ,Nephropathy ,chemistry.chemical_compound ,Internal medicine ,medicine ,Animals ,Rats, Wistar ,Creatinine ,business.industry ,Adenine ,medicine.disease ,Pathophysiology ,Rats ,Endocrinology ,chemistry ,Renal blood flow ,Kidney Failure, Chronic ,Chronic renal failure ,business ,Glomerular Filtration Rate - Abstract
Creatinine (Cr), creatol and methylguanidine (MG), which accumulate in the body with the progress of renal failure after adenine administration, were given separately to rats in order to compare their toxicities. Food containing adenine was given to rats for 20 days to induce renal failure. Then each of the test substances was administered intraperitoneally, and renal function of the rats was determined. The changes in glomerular filtration rate, renal plasma flow and renal blood flow after administration of Cr were only slight in comparison with those of the control group. Creatol or MG administration induced a significant decrease in renal function. In addition, the level of MG in serum, liver and kidney was extraordinarily high in rats given creatol or MG. The toxic effects are discussed on the basis of these results.
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- 1993
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29. In vivo Effect of Hydroxyl Radical Scavenger on Methylguanidine Production from Creatinine
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Naoki Fujitsuka, Ko Nakamura, Takako Yokozawa, Hikokichi Oura, and Kazuharu Ienaga
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Male ,Creatinine ,Hydroxyl Radical ,business.industry ,Thiourea ,Free Radical Scavengers ,Methylguanidine ,General Medicine ,Scavenger (chemistry) ,Rats ,chemistry.chemical_compound ,Biochemistry ,chemistry ,Nephrology ,In vivo ,Animals ,Medicine ,Hydroxyl radical ,Rats, Wistar ,business ,Injections, Intraperitoneal ,Uremia - Published
- 1997
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30. Reduced high serum hepatocyte growth factor levels after successful cardioversion in patients with atrial fibrillation
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Shin-ichi Inoue, Yoko Ohta, Nobuyuki Takahashi, Harumi Katoh, Akira Matsumori, Toshio Shimada, Ko Nakamura, Yo Murakami, Hiromi Shimizu, and Yutaka Ishibashi
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Male ,medicine.medical_specialty ,Heart disease ,Physiology ,medicine.medical_treatment ,Electric Countershock ,Cardioversion ,Physiology (medical) ,Internal medicine ,Atrial Fibrillation ,Medicine ,Plethysmograph ,Humans ,In patient ,Sinus rhythm ,Pharmacology ,business.industry ,Hepatocyte Growth Factor ,High serum ,Atrial fibrillation ,Middle Aged ,medicine.disease ,Treatment Outcome ,Anesthesia ,Cardiology ,Hepatocyte growth factor ,Female ,business ,medicine.drug - Abstract
SUMMARY 1. Serum hepatocyte growth factor (HGF) is considered to be a potent marker of vascular endothelial injury. The present study was designed to examine serum HGF levels in atrial fibrillation and after successful direct current (DC) cardioversion. 2. We measured serum HGF levels before and 7 days and 1 month after DC cardioversion in 39 patients with atrial fibrillation in whom sinus rhythm was maintained for at least 7 days after DC cardioversion and in 30 age- and sex-matched normal control subjects with sinus rhythm. We also measured acetylcholine-induced changes in forearm blood flow (FBF) using venous occlusive plethysmography in 10 patients. 3. Serum HGF levels were significantly higher in the atrial fibrillation patients (both lone atrial fibrillation and with underlying heart disease) than in the controls (0.16 ± 0.07 vs 0.10 ± 0.04 ng/mL; P
- Published
- 2004
31. Fully functional 0.5-μm 64-kbit embedded SBT FeRAM using a new low temperature SBT deposition technique
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S. Miyagaki, M. Mushiga, Yoshihiro Arimoto, Ko Nakamura, Hideki Yamawaki, Takashi Eshita, Masaki Aoki, A. Itho, and Sadahiro Kishii
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Materials science ,business.industry ,Electrical engineering ,Integrated circuit design ,law.invention ,Crystallization temperature ,CMOS ,law ,Ferroelectric RAM ,Ferroelectric thin films ,Optoelectronics ,Deposition (phase transition) ,Crystallization ,business - Abstract
0.5 /spl mu/m design rule embedded 64 kbit SBT (SrBi/sub 2/(Ta,Nb)/sub 2/O/sub 9/) FeRAMs (ferroelectric RAM) are fabricated using a new low temperature SBT deposition technique. The developed deposition technique has successfully lowered SBT crystallization temperature from 800/spl deg/C to 700/spl deg/C, resulting in co-fabrication of FeRAM and fine CMOS logic devices with W plugs. The fabricated devices are proven to be fully functional.
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- 2003
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32. In situ CMP monitoring technique for multi-layer interconnection
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Ko Nakamura, A. Fukuroda, and Yoshihiro Arimoto
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In situ ,Interconnection ,Signal processing ,Materials science ,GeneralLiterature_INTRODUCTORYANDSURVEY ,business.industry ,Polishing ,Accelerometer ,Chemical-mechanical planarization ,Hardware_INTEGRATEDCIRCUITS ,Electronic engineering ,Optoelectronics ,Head (vessel) ,Wafer ,business - Abstract
An all-around in situ monitor for CMP was developed. It can detect the even surface during planarization, polishing pad wear, lack of uniformity on the surface of a wafer, and the interface of different materials. In this method, small vibrations of the polishing head were detected by using an accelerometer, and signal processing techniques were used to determine polishing events.
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- 2002
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33. Pulmonary venous systolic flow: influence of gravity on pulmonary venous flow velocities assessed in patients with atrial fibrillation
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Tetsuro Ohta, Yoko Ohta, Kazuaki Tanabe, Ko Nakamura, Hiromi Shimizu, and Toshio Shimada
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Male ,medicine.medical_specialty ,Pulmonary Circulation ,Supine position ,Atrial Pressure ,Venous flow ,Doppler transesophageal echocardiography ,Internal medicine ,Recumbent Position ,Atrial Fibrillation ,medicine ,Supine Position ,Humans ,Mitral Valve Stenosis ,Radiology, Nuclear Medicine and imaging ,In patient ,Cardiac Output ,Aged ,Aged, 80 and over ,business.industry ,Atrial fibrillation ,Middle Aged ,medicine.disease ,Stenosis ,Pulmonary Veins ,Cardiology ,Atrial Function, Left ,Female ,Cardiology and Cardiovascular Medicine ,business ,Blood Flow Velocity ,Echocardiography, Transesophageal ,Gravitation - Abstract
The origin of the pulmonary venous (PV) systolic flow wave is still unclear and could be the atrial relaxation and systolic descent of the atrioventricular plane, which decrease atrial pressure (suction) or raised PV pressure. In atrial fibrillation (AF), loss of atrial contraction and relaxation significantly modifies the systolic PV flow wave. The effect of recumbent positional changes on PV, however, has not yet been characterized in AF. The purpose of this study was to evaluate the effect of positional changes on systolic PV flow in patients with AF studied by transesophageal echocardiography. The study group consisted of 45 patients with AF (34 patients with AF, alone, and 11 patients with mitral stenosis [MS]). To assess the influence of left atrial pressure, we included patients with MS and AF. Pulsed wave Doppler transesophageal echocardiography of the left and right upper PV were performed in the left lateral recumbent position in all patients and repeated records were obtained with the subject in the supine position in 25 (AF alone: n = 20, MS: n = 5) of 45 patients. In the left lateral recumbent position, the systolic PV flow velocity and systolic fraction of the left PV, which were recorded on the recumbent subject's lower side, were significantly increased compared with those of the right PV in both AF alone and MS with AF (33.9 +/- 10.8 vs 13.8 +/- 6.4 cm/s, 0.45 +/- 0.09 vs 0.20 +/- 0.10 in AF alone; 30.2 +/- 11.7 vs 14.6 +/- 6.0 cm/s, 0.43 +/- 0.12 vs 0.20 +/- 0.07 in MS, respectively, P.01). By changing the position from the left lateral to the supine position, systolic PV flow velocity and systolic fraction of the left and right PV became the same (29.3 +/- 8.4 vs 27.9 +/- 8.4 cm/s, 0.39 +/- 0.09 vs 0.36 +/- 0.06 in AF alone, 23.5 +/- 8.8 vs 27.5 +/- 5.0 cm/s, 0.35 +/- 0.08 vs 0.35 +/- 0.09 in MS, respectively). These findings show that the PV volume (hydrostatic pressure) significantly modifies systolic PV flow wave in patients without atrial contraction and relaxation. We should take into consideration the body position on which PV flow is studied.
- Published
- 2002
34. High plasma brain natriuretic polypeptide level as a marker of risk for thromboembolism in patients with nonvalvular atrial fibrillation
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Yutaka Ishibashi, Yoko Ohta, Yo Murakami, Ko Nakamura, Takashi Sugamori, Shuzo Ohata, Takeshi Sakne, Toshio Shimada, Nobuyuki Takahashi, Hiromi Shimizu, Harumi Katoh, and Shin-ichi Inoue
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Adult ,Male ,medicine.medical_specialty ,Heart disease ,Risk Assessment ,Electrocardiography ,Predictive Value of Tests ,Internal medicine ,Thromboembolism ,Blood plasma ,Atrial Fibrillation ,Natriuretic Peptide, Brain ,medicine ,Humans ,Atrial Appendage ,Thrombus ,Atrium (heart) ,Aged ,Advanced and Specialized Nursing ,Aged, 80 and over ,business.industry ,Vascular disease ,Myocardium ,Atrial fibrillation ,Middle Aged ,medicine.disease ,Brain natriuretic peptide ,medicine.anatomical_structure ,Logistic Models ,Heart failure ,Chronic Disease ,Cardiology ,Atrial Function, Left ,Female ,Neurology (clinical) ,Cardiology and Cardiovascular Medicine ,business ,Atrial Natriuretic Factor ,Biomarkers ,Blood Flow Velocity ,Echocardiography, Transesophageal - Abstract
Background and Purpose — Assessment of left atrial appendage (LAA) function with transesophageal echocardiography is useful for detecting patients at high risk for thromboembolism as a result of atrial fibrillation (AF). A recent study reported that the atrium is the main source of brain natriuretic polypeptide (BNP) in AF patients without overt heart failure. The purpose of this study was to assess a possible relationship between LAA function and plasma BNP levels in nonvalvular AF. Methods — Thirty-four consecutive patients with chronic nonvalvular AF (age, 69±9 years) underwent transesophageal echocardiography and plasma BNP measurement. Thirteen patients with a history of thromboembolism or echocardiographic evidence of thrombus (E + group) were compared with 21 AF patients without complications (E− group). Results — The E+ group patients demonstrated greater impairment of LAA velocity and higher plasma BNP levels than the E− group patients (LAA velocity: 12±6 versus 31±17 cm/s, P P r =0.38, P Conclusions — The present data suggest the usefulness of measuring plasma BNP levels, which may reflect augmented atrial secretion of BNP from the impaired atrial myocardium, in detecting patients at high risk for thromboembolic complications in nonvalvular AF.
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- 2002
35. Prognostic significance of elevated plasma brain natriuretic polypeptide in patients with chronic renal failure treated with hemodialysis
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Yo Murakami, Yoko Ohta, Nobuyuki Takahashi, Hiromi Shimizu, Nobuyuki Oyake, Toshio Shimada, Yutaka Ishibashi, Harumi Katoh, Keiko Suzuki, Shin-ich Inoue, and Ko Nakamura
- Subjects
medicine.medical_specialty ,business.industry ,Internal medicine ,medicine.medical_treatment ,medicine ,Chronic renal failure ,In patient ,Hemodialysis ,Intensive care medicine ,business ,Cardiology and Cardiovascular Medicine ,Gastroenterology - Published
- 2002
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36. Atrial fibrillation impairs endothelial function of forearm vessels in humans
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Kazuya Sano, Takashi Sugamori, Yoko Ohta, Nobuyuki Takahashi, Takeshi Sakane, Shuzo Ohata, Hiromi Shimizu, Ko Nakamura, Shin-ichi Inoue, Harumi Katoh, Yutaka Ishibashi, Michio Hashimoto, Toshio Shimada, and Yo Murakami
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Cardiac function curve ,Male ,medicine.medical_specialty ,Heart disease ,Endothelium ,medicine.medical_treatment ,Electric Countershock ,Vasodilation ,Cardioversion ,Nitroglycerin ,Internal medicine ,Atrial Fibrillation ,medicine ,Plethysmograph ,Humans ,Sinus rhythm ,Aged ,business.industry ,Atrial fibrillation ,Middle Aged ,medicine.disease ,Acetylcholine ,body regions ,Forearm ,medicine.anatomical_structure ,Treatment Outcome ,Regional Blood Flow ,Anesthesia ,Cardiology ,Female ,Vascular Resistance ,Endothelium, Vascular ,Cardiology and Cardiovascular Medicine ,business - Abstract
Background: Although there have been many studies on the effects of atrial fibrillation (AF) on cardiac function, few studies have been done on its effects on endothelial function. The present study was designed to examine the effects of AF on endothelial function in human subjects. Methods and Results: Changes in forearm blood flow (FBF) induced by acetylcholine and nitroglycerin were measured by using plethysmography in 14 patients with lone AF, 13 patients with AF and underlying heart disease, and 12 normal control subjects. In the patients, these measurements were repeated after cardioversion. Although baseline FBF was the same in the 3 groups, acetylcholine-induced increases in FBF were significantly smaller in both patient groups than in the control group, and FBF increases were particularly depressed in AF patients with underlying heart disease. After restoration of sinus rhythm by cardioversion, FBF response to the highest dose of acetylcholine increased by 46% in patients with lone AF (n = 10) and by 90% in AF patients with underlying heart disease (n = 11). Nitroglycerin-induced vasodilatation was the same in all 3 groups and was not affected by cardioversion. Conclusions: These findings suggest that endothelium-dependent vasodilatation is impaired by AF and improves after sinus rhythm is restored.
- Published
- 2001
37. Impaired vasodilatation response to amrinone in the forearm of patients with congestive heart failure: role of endothelium-derived nitric oxide
- Author
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Yoshifumi Hirano, Takeshi Sakane, Nobuyuki Takahashi, Takashi Sugamori, Shin-ichi Inoue, Toshio Shimada, Shuzo Ohata, Yo Murakami, Ko Nakamura, and Yutaka Ishibashi
- Subjects
Male ,medicine.medical_specialty ,Endothelium ,Nitric Oxide Synthase Type III ,Vasodilator Agents ,Vasodilation ,Nitric Oxide ,Amrinone ,Nitric oxide ,chemistry.chemical_compound ,Nitroglycerin ,Internal medicine ,medicine ,Humans ,Endothelial dysfunction ,Enzyme Inhibitors ,Aged ,Pharmacology ,Heart Failure ,omega-N-Methylarginine ,business.industry ,Hemodynamics ,Middle Aged ,medicine.disease ,Acetylcholine ,Forearm ,medicine.anatomical_structure ,Endocrinology ,chemistry ,Regional Blood Flow ,Heart failure ,Cardiology ,Female ,Endothelium, Vascular ,Nitric Oxide Synthase ,Cardiology and Cardiovascular Medicine ,business ,Artery ,medicine.drug - Abstract
Recent in vitro experiments have shown that amrinone enhances the release of nitric oxide (NO) from the endothelium and induces NO mediated vasodilatation. This in vivo study examined whether amrinone causes vasodilatation mediated by endothelium-derived NO, and whether this effect is attenuated in patients with endothelial dysfunction. Eight patients with congestive heart failure and 10 age- and sex-matched healthy volunteers were studied. Forearm blood flow (FBF) was measured before and during infusion of drugs of acetylcholine, amrinone, and nitroglycerin in incremental doses. After the completion of these measurements, 100 micromol of N(G)-monomethyl-L-arginine (L-NMMA) was infused intraarterially. Thereafter, FBF measurement in response to incremental doses of amrinone was repeated. Infusion of incremental doses of amrinone caused a comparable increase in amrinone plasma concentration in both groups. Baseline FBF was 3.2+/-0.79 ml/min/100 ml in controls vs. 2.91+/-0.79 ml/min/100 ml in patients (p = 0.43). In both groups, FBF increased in response to acetylcholine, amrinone, and nitroglycerin. During infusion of the highest dose of nitroglycerin, FBF was not different between the two groups (p = 0.51); however, FBF during infusion of the highest doses of acetylcholine and amrinone was significantly less in patients than in controls: 9.75+/-2.69 vs. 24.87+/-8.65 ml/min/100 ml (p < 0.001) and 3.79+/-1.21 vs. 7.15+/-2.06 ml/min/100 ml (p < 0.001), respectively. L-NMMA significantly depressed the increase in FBF in response to amrinone in controls, but not in patients. In conclusion, the selective PDE III inhibitor, amrinone, has endothelium-derived NO-mediated vasodilating effects in addition to direct effects. This property may be impaired in patients with endothelial dysfunction.
- Published
- 2000
38. Morphologic features of vulnerable coronary atherosclerotic plaque: intravascular ultrasound demonstration with prospective follow-up study
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Yoshio Yasumura, Kenichi Ito, Satoshi Nakatani, Masakazu Yamagishi, Kunio Miyatake, M. Kijima, Ko Nakamura, and Satoshi Daikoku
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medicine.medical_specialty ,medicine.diagnostic_test ,business.industry ,Intravascular ultrasound ,medicine ,Follow up studies ,Radiology ,business ,Cardiology and Cardiovascular Medicine - Published
- 1998
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39. Relationship between progressive microvascular damage and intramyocardial hemorrhage in patients with reperfused anterior myocardial infarction: myocardial contrast echocardiographic study
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Koichi Ochiai, Yo Murakami, Rinji Murakami, Kazuya Sano, Toshihiko Asanuma, Shintaro Beppu, Kazuaki Tanabe, Hiroyuki Yoshitomi, Ko Nakamura, Toshio Shimada, and Shigefumi Morioka
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Male ,medicine.medical_specialty ,Myocardial Infarction ,Myocardial Ischemia ,Anterior myocardial infarction ,Hemorrhage ,Myocardial Reperfusion Injury ,Microcirculation ,Physiology (medical) ,Internal medicine ,medicine ,Humans ,In patient ,cardiovascular diseases ,Myocardial infarction ,Aged ,medicine.diagnostic_test ,business.industry ,Magnetic resonance imaging ,Middle Aged ,medicine.disease ,Coronary Vessels ,Magnetic Resonance Imaging ,Coronary heart disease ,Echocardiography ,cardiovascular system ,Cardiology ,Female ,Myocardial disease ,Cardiology and Cardiovascular Medicine ,business ,Complication - Abstract
Background Recent studies indicated that ischemic microvascular damage may be reversible or progressive after coronary reflow. Intramyocardial hemorrhage is a phenomenon that reflects severe microvascular injury. We examined the relationship between temporal changes in microvascular perfusion patterns detected by myocardial contrast echocardiography (MCE) and intramyocardial hemorrhage detected by magnetic resonance imaging (MRI) in patients with acute myocardial infarction (AMI). Methods and Results The study population consisted of 24 patients with anterior AMI. All patients underwent MCE shortly after reflow and in the chronic stage (a mean of 31 days after reflow). Wall motion score (WMS) was determined as the sum of 16 segmental scores (dyskinetic/akinetic=3 to normal=0) at days 1 and 31. Gradient-echo acquisition and gadolinium-DTPA–enhanced spin-echo MRI were performed within 10 days after reflow. In MCE shortly after reflow, 16 patients (67%) showed contrast enhancement and the other 8 patients (33%) showed a sizable contrast defect. In the chronic stage, a persistent contrast defect was observed in 7 of 8 patients with a contrast defect shortly after reflow. Consistent contrast enhancement was observed in 12 of 16 patients (75%) with contrast enhancement shortly after reflow, indicating that a contrast defect newly appeared in 4 patients (25%). Intramyocardial hemorrhage was detected in 9 patients (38%): 5 of 7 patients with a persistent contrast defect and in all 4 patients with a new appearance of a contrast defect during the chronic stage. The patients without hemorrhage showed a significant improvement in WMS compared with patients with hemorrhage at day 31 (5±5 versus 19±6, P Conclusions These results suggest that irreversible microvascular damage to the ischemic myocardium may cause intramyocardial hemorrhage after reflow, associated with impaired recovery of left ventricular function. Contrast enhancement within the risk area shortly after reflow does not necessarily indicate long-term microvascular salvage.
- Published
- 1997
40. Diabetic renal failure and serum accumulation of the creatinine oxidative metabolites creatol and methylguanidine
- Author
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Takahiro Kanatsuna, Motoharu Kondo, Goji Hasegawa, Ko Nakamura, Kazuharu Ienaga, Masahiko Nakai, Yoshio Nakamura, Manabu Sawada, Hiroshi Mori, and Koji Nakano
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Male ,medicine.medical_specialty ,Metabolite ,Oxidative phosphorylation ,Methylguanidine ,medicine.disease_cause ,chemistry.chemical_compound ,Internal medicine ,medicine ,Humans ,Diabetic Nephropathies ,Autoimmune disease ,Creatinine ,business.industry ,Middle Aged ,medicine.disease ,Pathophysiology ,CTL ,Oxidative Stress ,Endocrinology ,chemistry ,Kidney Failure, Chronic ,Female ,business ,Oxidation-Reduction ,Oxidative stress - Abstract
Diabetic patients (n = 23) with chronic renal failure (CRF) accumulate the creatinine (Cr) oxidative metabolites creatol (CTL) and methylguanidine (MG; a uremic toxin) in their sera. Analysis of serum CTL, a key intermediate in mammalian Cr catabolism into MG, is shown to offer some useful diagnostic information on CRF, especially in the determination of an initial stage of pathological renal failure. The sera of all diabetic (n = 23) and nondiabetic (n = 20) patients with CRF (s-Cr1.25 mg/dl) contained s-CTL (2 micrograms/dl), whereas those from normal subjects (n = 18) and diabetic patients (n = 18) without CRF contained no detectable s-CTL. A similar accumulation of s-MG was observed, but only when s-Cr was higher than 2.0 mg/dl. Although each s-CTL (Y: microgram/dl, Y': mol/l) and s-MG level (Z: microgram/dl, Z': mol/l) is highly correlated with s-Cr (X: mg/dl, X': mol/l) in a normal equation, Y or Z = AX + B, an alternative correlation in a second-order equation, Y or Z = alpha X2 + beta X, could also fit well. Since the quadratic equation can be convertible to Y/X or Z/X = alpha X + beta [Y'/X' or Z'/X' = alpha' X+ beta'] and active oxygen species, especially hydroxyl radicals, convert Cr into CTL, Y/X, Y'/X', Z/X and Z'/X' values which might be a kind of indices for oxygen stress (oxidative stress) increased in proportion to the increased severity of CRF in such patients. Although its meaning and interpretation are still debatable, diabetic CRF patients had a significantly higher alpha' value (2.2) than that (0.89) of nondiabetic CRF patients. All serum values for Cr, CTL and MG were measured with HPLC.
- Published
- 1996
41. Dielectric SiO2Planarization Using MnO2Slurry
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Syuhei Kurokawa, Sadahiro Kishii, Kenzo Hanawa, Yoshihiro Arimoto, Ko Nakamura, Satoru Watanabe, and Toshiro Doi
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Gate dielectric ,General Engineering ,General Physics and Astronomy ,Optoelectronics ,Dielectric ,business ,Dielectric spectroscopy - Published
- 2012
- Full Text
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42. Creatol, a creatinine metabolite, as a useful determinant of renal function
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Takahiro Kanatsuna, Hiroshi Mori, Yoshio Nakamura, Kazuharu Ienaga, Koji Nakano, Manabu Sawada, Ko Nakamura, Masahiko Nakai, Motoharu Kondo, and Goji Hasegawa
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medicine.medical_specialty ,Metabolite ,Renal function ,chemical and pharmacologic phenomena ,Urine ,Kidney ,chemistry.chemical_compound ,Drug Stability ,Molar ratio ,Reference Values ,Stress, Physiological ,Internal medicine ,Medicine ,Humans ,In patient ,Chromatography, High Pressure Liquid ,Creatinine ,business.industry ,Reproducibility of Results ,hemic and immune systems ,Oxygen ,CTL ,Endocrinology ,chemistry ,Solubility ,Calibration ,Chronic renal failure ,Kidney Failure, Chronic ,business - Abstract
Analysis of creatol (CTL, 5-hydroxycreatinine), an oxidative creatinine (Cr) metabolite, in serum and urine of human subjects has indicated that CTL is a useful determinant of renal function. The existence itself of serum CTL (s-CTL) could be a diagnostic sign for chronic renal failure (CRF): in all normal subjects, s-CTL was undetectable, but s-CTL was detectable in sera of all patients with CRF (s-Cr: > 2.0 mg/dl). And the s-CTL values increased in proportion to the severity of CRF in such patients. Furthermore, the molar ratio (CTL/Cr) in both urine and serum increased significantly in proportion to the severity of CRF. Our results indicated not only hyperproduction of CTL but also higher oxygen stress in patients according to the progression of CRF. The diagnostic importance of the CTL value and the CTL/Cr ratio are discussed.
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- 1994
43. Pediatric orbital eosinophilic granuloma with intra- and extracranial extension--case report
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Yoshiaki Kumon, Takao Hatakeyama, Ko Nakamura, Shigeru Furuta, and Saburo Sakaki
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Male ,medicine.medical_specialty ,Computed tomographic ,Lesion ,Eosinophilic granuloma ,Histological diagnosis ,medicine ,Humans ,Neoplasm Invasiveness ,medicine.diagnostic_test ,business.industry ,Magnetic resonance imaging ,medicine.disease ,Mr imaging ,eye diseases ,Eosinophilic Granuloma ,Radiography ,medicine.anatomical_structure ,Child, Preschool ,Orbital Neoplasms ,Surgery ,sense organs ,Neurology (clinical) ,Radiology ,medicine.symptom ,business ,Lateral wall ,Orbit (anatomy) - Abstract
A rare case of eosinophilic granuloma of the orbit in a 3-year-old boy presented as right upper eyelid swelling and proptosis. Computed tomographic scanning revealed a soft-tissue dense mass in the lateral wall of the right orbit. Magnetic resonance (MR) imaging demonstrated tumor extension into the orbit, anterior and middle cranial fossae, and extracranial region. The tumor was completely removed. Histological diagnosis was eosinophilic granuloma. No evidence of recurrence was found 14 months later. MR imaging is useful for diagnosis of the lesion, and particularly for surgical management.
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- 1991
44. Production of methylguanidine from creatinine via creatol by active oxygen species: analyses of the catabolism in vitro
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Hikokichi Oura, Naoki Fujitsuka, Kazuharu Ienaga, Ko Nakamura, and Takako Yokozawa
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inorganic chemicals ,Magnetic Resonance Spectroscopy ,Free Radicals ,Metabolite ,Iron ,chemistry.chemical_element ,Oxidative phosphorylation ,Methylguanidine ,Oxygen ,chemistry.chemical_compound ,Hydroxides ,Medicine ,Hydrogen peroxide ,Chromatography, High Pressure Liquid ,Chromatography ,Molecular Structure ,Catabolism ,business.industry ,Hydroxyl Radical ,Hydrolysis ,Free Radical Scavengers ,Hydrogen Peroxide ,chemistry ,Biochemistry ,Reagent ,Creatinine ,Hydroxyl radical ,business ,Oxidation-Reduction - Abstract
The chemical oxidative conversion of creatinine (Cr) into methylguanidine (MG) has been followed by 1H-NMR and HPLC. By using active oxygen species generated by Fenton's reagent (Fe2+ and H2O2) or the similar reagent (Fe3+ and H2O2), creatol (CTL), a metabolite newly isolated from the urine of uremic patients, and creatones A and B were experimentally detected in the reaction mixture and implicated as successive intermediates in the pathway from CR to MG. An alternative oxidation of Cr to demethylcreatinine (glycocyamidine) was also observed. The importance of CTL in this in vitro oxidation mechanism is discussed.
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- 1991
45. Subject Index, Vol. 63, 1993
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Lg. Burdiel, Chikao Yasunaga, C. Zoccali, V. Minkova, F. Tricot, G. Decaux, V. Jacobs, A.R. Reshi, Ana Gonzalo, S. Ringoir, F. Fabrizi, M. Rivera, M.J. Richard, Philippe Lesavre, S.K. Pehrsson, Micheline Levy, Ikuko Hayashi, Yutaka Emoto, M. Postorino, Laure-Hélène Noël, Esmeray Acartürk, S.C. Tiwari, Caje Moniz, C. Gonzalez, J. Ortuño, W. Van Biesen, A. Mouneimne, Pierre Simon, Phil Tuso, B. Namias, R. Saxena, J. Lacueva, Francisco J. Pérez Fontán, A. Shouzu, Masashi Ishida, M. Tanvir, J.V. Tovar, J.B. Cabezuelo, Miguel Pérez Fontán, Ana Rodríguez-Carmona, Bernard Mattlinger, T. Jogestrand, A. Davenport, M. Bogićević, L.-E. Lins, Donald E. Potter, Ching-Yuang Lin, Richard E. Schell, B.M. Jones, Joanne T Marsden, Takashi Yasuda, Atsushi Aikawa, G. Curatola, J.A. Ruiz, S.C. Dash, F. Prospert, M.S. Najar, Eiisa Menegatti, P. Aljama, M.A. Waterloos, Francisco Mampaso, Monique Menault, Marie-Paule Ramée, Nan Chen, D. Krzemień, Victor Parsons, Bernard F. Jones, Kenji Maeda, R. Vanholder, Kazuharu lenaga, M. Esbjörnsson, E. Jansson, V. Stefanović, Akira Hasegawa, J.L. Teruel, Q. Maggiore, S.N. Mehta, F. Pizzarelli, J.C. Castaño, Giuseppe Piccoli, Sadanobu Ozawa, M. Altaf, Chiou-Chyn Lin, Sonoo Mizuiri, R. Enriquez, S. Nomura, Teruaki Akao, M. Nishikawa, Donald Nortman, Kazuharu Ienaga, K. Sirajeddine, Masaaki Takano, Michelle Barnett, G.H. Malik, Tomoyuki Katsuzak, Tomoko Yazawa, A. Dhondt, L.A. Sirwal, D. Mittal, Rafael Bárcena, D. Cordonnier, I.K.P. Cheng, Hikokichi Oura, E. Niembro, Naoki Fujitsuka, Ko Nakamura, M.C. Denis, M. Mitić, D. Castillo, Takehiro Ohara, Dario Roccatello, M. Espinosa, N. Belovezhdov, Cristiana Rollino, T. Kokawa, R. Čuiairanović, Joaquín Ortuño, Elizabeth Ball, Noriyuki Tatemichi, S.K. Agarwal, Ian R. Rifkin, Tung-Po Huang, Chikako Shiba, Takako Yokozawa, Antonio Soto, R. Dell’Aquila, Tsukasa Kanazawa, Toshimitsu Niwa, Bruno Basolo, R. Penninckx, K. Yasunaga, R. Perez, N. Clyne, I. Altunkova, P. Vlahović, N. Van Landschoot, Masao Hattori, N. Veys, Teruhiko Maeba, Makoto Sugiyama, A. Soupart, Saime Paydas, G. Garcia Otero, Dianne Baldwin, Kyoichi Kobashi, A. Martin-Malo, Jw. Naskalski, Takashi Miyazaki, Francisco Pombo, S. Saxena, P. Benito, Shigeru Owada, and Antonio Zea
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Index (economics) ,business.industry ,Statistics ,Medicine ,Subject (documents) ,business - Published
- 1993
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46. Comparison of Methylguanidine Production from Creatinine and Creatol in vivo
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Takako Yokozawa, Hikokichi Oura, Naoki Fujitsuka, Ko Nakamura, and Kazuharu Ienaga
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Creatinine ,chemistry.chemical_compound ,medicine.medical_specialty ,Endocrinology ,chemistry ,In vivo ,business.industry ,Internal medicine ,medicine ,Methylguanidine ,business - Published
- 1991
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47. An inhibitor of inducible nitric oxide synthase decreases forearm blood flow in patients with congestive heart failure
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Michio Hashimoto, Ko Nakamura, Yoko Ohta, Takashi Sugamori, Shuzo Ohata, Shin-ichi Inoue, Yutaka Ishibashi, Yo Murakami, Hiromi Shimizu, Harumi Katoh, Nobuyuki Takahashi, Toshio Shimada, and Takeshi Sakane
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Adult ,Male ,medicine.medical_specialty ,Time Factors ,Endothelium ,Heart disease ,Hemodynamics ,Nitric Oxide ,Guanidines ,Severity of Illness Index ,Nitric oxide ,chemistry.chemical_compound ,Forearm ,medicine.artery ,Internal medicine ,Natriuretic Peptide, Brain ,medicine ,Humans ,Brachial artery ,Aged ,Heart Failure ,Analysis of Variance ,omega-N-Methylarginine ,Dose-Response Relationship, Drug ,biology ,business.industry ,Middle Aged ,medicine.disease ,Acetylcholine ,Plethysmography ,Vasodilation ,Nitric oxide synthase ,Endocrinology ,medicine.anatomical_structure ,chemistry ,Case-Control Studies ,Heart failure ,Disease Progression ,biology.protein ,Female ,Endothelium, Vascular ,Drug Monitoring ,Nitric Oxide Synthase ,Cardiology and Cardiovascular Medicine ,business ,Atrial Natriuretic Factor ,Blood Flow Velocity - Abstract
OBJECTIVESThe functional activation of inducible nitric oxide synthase (iNOS) was evaluated as a source of nitric oxide (NO) in the forearm of patients with heart failure.BACKGROUNDAlthough endogenous NO is normally produced by constitutive NO synthase (cNOS) in patients with congestive heart failure (CHF), expression of iNOS provides an additional source of NO. However, there are no in vivo studies showing functional activation of iNOS in humans.METHODSA nonselective NOS inhibitor, NG-monomethyl-L-arginine (L-NMMA), and a selective inhibitor of iNOS, aminoguanidine, were administered intra-arterially in graded doses into the brachial arteries of 13 patients with CHF and 10 normal control subjects. Forearm blood flow (FBF) was measured simultaneously in the infused and noninfused arms by plethysmography. Arterial and venous plasma concentrations of nitrite/nitrate (NOx) were measured at baseline and at the highest dose of each drug.RESULTSL-NMMA significantly reduced the FBF ratio between the infused and noninfused arms in both the control and patient groups (35 ± 12% and 34 ± 10%, respectively; both p < 0.001). Aminoguanidine at the same concentration significantly reduced the ratio in the patient group (15 ± 9%, p < 0.01), with no change in the control group. The arterial NOx concentration was not affected by either drug; however, venous NOx concentrations were significantly decreased in both the control and patient groups by L-NMMA (18 ± 5% and 18 ± 17%, respectively; both p < 0.05) and in the patient group only by aminoguanidine (7 ± 6%, p < 0.05).CONCLUSIONSThese findings suggest that NO production in the forearms of patients with CHF is induced partly by iNOS activation, whereas in normal subjects, it can be ascribed to cNOS activation.
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