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Hasegawa M, Nakamura K, Zushi H, Hanada K, Fujisawa A, Matsuoka K, Mitarai O, Idei H, Nagashima Y, Tokunaga K, Kawasaki S, Nakashima H, Higashijima A. Development of plasma control system for divertor configuration on QUEST. FUSION ENGINEERING AND DESIGN 2013. [DOI: 10.1016/j.fusengdes.2013.03.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Kobayashi T, Itoh K, Ido T, Kamiya K, Itoh SI, Miura Y, Nagashima Y, Fujisawa A, Inagaki S, Ida K, Hoshino K. Spatiotemporal structures of edge limit-cycle oscillation before L-to-H transition in the JFT-2M tokamak. PHYSICAL REVIEW LETTERS 2013; 111:035002. [PMID: 23909334 DOI: 10.1103/physrevlett.111.035002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Indexed: 06/02/2023]
Abstract
In this Letter, we report analyses of spatiotemporal dynamics of turbulence and structure in the limit-cycle oscillation (LCO) that precedes an L-to-H transition. Zonal flows are not observed during LCO, and the oscillation is the periodic generations or decays of barrier with edge-localized mean flow. Oscillatory Reynolds stress is found to be too small to accelerate the LCO flow, by considering the dielectric constant in magnetized toroidal plasmas. Propagation of changes of the density gradient and turbulence amplitude into the core is also observed.
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Tokunaga M, Endo Y, Fujisawa A, Tanioka M, Nomura T, Miyachi Y. Improvement in telangiectatic rosacea as a side-effect of monthly docetaxel therapy. Clin Exp Dermatol 2013; 39:262-3. [PMID: 23763600 DOI: 10.1111/ced.12180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2013] [Indexed: 12/24/2022]
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Ono S, Tanioka M, Tanizaki H, Fujisawa A, Koga H, Hashimoto T, Kamiya K, Aoyama Y, Iwatsuki K, Miyachi Y. Concurrence of autoantibodies to bullous pemphigoid antigens and desmoglein 3: analysis of pathogenic and nonpathogenic antibodies. Br J Dermatol 2013; 168:1357-60. [PMID: 23738642 DOI: 10.1111/bjd.12143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Banerjee S, Zushi H, Nishino N, Nagashima Y, Hanada K, Ishiguro M, Ryoukai T, Tashima S, Inoue T, Nakamura K, Idei H, Hasegawa M, Fujisawa A, Matsuoka K. Fast visible imaging and edge turbulence analysis in QUEST. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:10E524. [PMID: 23127031 DOI: 10.1063/1.4739080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A fast visible imaging system is installed on the spherical tokamak QUEST to study edge turbulence. The camera uses a complementary metal-oxide semiconductor detector with a maximum resolution of 1024 × 1024 at 7000 frames∕s (fps) and can achieve 775 kfps at a resolution of 128 × 24. In this paper, we present the salient features of the system and its application to study edge turbulence in 8.2 GHz ECRH driven slab plasma, without plasma current. Vertical magnetic field (B(z)) topology is varied with three sets of poloidal field (PF) coils and the variation in the edge turbulence is investigated as a function of the B(z) strength and curvature. Fluctuation amplitude was highest for the shallow PF well. Cross-correlation coefficient shows distinct coherent mode along z direction at the steep density gradient region and it grows with the PF mirror ratio.
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Sharma S, Zushi H, Yoshida N, Watanabe H, Osakabe M, Takeri Y, Hasegawa M, Tanabe T, Tokunaga K, Hanada K, Idei H, Sakamoto M, Nakamura K, Fujisawa A, Ishiguro M, Tashima S. Analysis of PWI footprint traces and material damage on the first walls of the spherical tokamak QUEST. FUSION ENGINEERING AND DESIGN 2012. [DOI: 10.1016/j.fusengdes.2011.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ichihara A, Jinnin M, Yamane K, Fujisawa A, Sakai K, Masuguchi S, Fukushima S, Maruo K, Ihn H. microRNA-mediated keratinocyte hyperproliferation in psoriasis vulgaris. Br J Dermatol 2011; 165:1003-10. [PMID: 21711342 DOI: 10.1111/j.1365-2133.2011.10497.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Psoriasis is a chronic inflammatory skin disease characterized by intense proliferation and abnormal differentiation of keratinocytes, although the pathogenesis is still not completely clarified. OBJECTIVES We investigated the mechanism of keratinocyte proliferation seen in psoriasis, focusing on microRNA (miRNA). MATERIALS AND METHODS miRNAs were extracted from tissues and sera of psoriasis, atopic dermatitis and healthy control. To determine pathogenic miRNAs, we performed miRNA polymerase chain reaction (PCR) array analysis. The results were confirmed with quantitative real-time PCR, in situ hybridization, immunohistochemistry, transient transfection of siRNA and inhibitor in cultured keratinocytes and Western blotting. RESULTS PCR array analysis using tissue miRNA demonstrated miR-424 level was markedly decreased in psoriasis skin in vivo. Protein expression of mitogen-activated protein kinase kinase 1 (MEK1) or cyclin E1, predicted target genes of miR-424, was increased in psoriatic skin, although their mRNA levels were not. The transfection of specific inhibitor of miR-424 in normal human keratinocytes led to upregulation of MEK1 or cyclin E1 protein, and resulted in increased cell proliferation. On the other hand, cell number was significantly decreased when cells were transfected with siRNA for MEK1 or cyclin E1. Furthermore, we first investigated serum miRNA levels in psoriasis. Although not significant, serum miR-424 concentration tended to be decreased in patients with psoriasis compared with healthy controls. CONCLUSIONS Decreased miR-424 expression and subsequently increased MEK1 or cyclin E1 may play a key role in the pathogenesis of psoriasis. Investigation of the regulatory mechanisms of keratinocyte proliferation by miRNA may lead to new treatments and a disease activity marker.
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Inagaki S, Tokuzawa T, Itoh K, Ida K, Itoh SI, Tamura N, Sakakibara S, Kasuya N, Fujisawa A, Kubo S, Shimozuma T, Ido T, Nishimura S, Arakawa H, Kobayashi T, Tanaka K, Nagayama Y, Kawahata K, Sudo S, Yamada H, Komori A. Observation of long-distance radial correlation in toroidal plasma turbulence. PHYSICAL REVIEW LETTERS 2011; 107:115001. [PMID: 22026678 DOI: 10.1103/physrevlett.107.115001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Indexed: 05/31/2023]
Abstract
This Letter presents the discovery of macroscale electron temperature fluctuations with a long radial correlation length comparable to the plasma minor radius in a toroidal plasma. Their spatiotemporal structure is characterized by a low frequency of ∼1-3 kHz, ballistic radial propagation, a poloidal or toroidal mode number of m/n=1/1 (or 2/1), and an amplitude of ∼2% at maximum. Nonlinear coupling between the long-range fluctuations and the microscopic fluctuations is identified. A change of the amplitude of the long-range fluctuation is transmitted across the plasma radius at the velocity which is of the order of the drift velocity.
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Yamada T, Itoh SI, Inagaki S, Nagashima Y, Kasuya N, Kamataki K, Arakawa H, Kobayashi T, Yagi M, Fujisawa A, Itoh K. Observation of quasi-two-dimensional nonlinear interactions in a drift-wave streamer. PHYSICAL REVIEW LETTERS 2010; 105:225002. [PMID: 21231392 DOI: 10.1103/physrevlett.105.225002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Indexed: 05/30/2023]
Abstract
A streamer, which is a bunching of drift-wave fluctuations, and its mediator, which generates the streamer by coupling with other fluctuations, have been observed in a cylindrical magnetized plasma. Their radial structures were investigated in detail by using the biphase analysis. Their quasi-two-dimensional structures were revealed to be equivalent with a pair of fast and slow modes predicted by a nonlinear Schrödinger equation based on the Hasegawa-Mima model.
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Makino T, Jinnin M, Muchemwa F, Fukushima S, Kogushi-Nishi H, Moriya C, Igata T, Fujisawa A, Johno T, Ihn H. Basic fibroblast growth factor stimulates the proliferation of human dermal fibroblasts via the ERK1/2 and JNK pathways. Br J Dermatol 2009; 162:717-23. [DOI: 10.1111/j.1365-2133.2009.09581.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Yamada T, Nagashima Y, Inagaki S, Kawai Y, Yagi M, Itoh SI, Maruta T, Shinohara S, Terasaka K, Kawaguchi M, Fukao M, Fujisawa A, Itoh K. Fine positioning of a poloidal probe array. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2007; 78:123501. [PMID: 18163726 DOI: 10.1063/1.2818796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Multipoint detection is an essential requirement for investigating plasma turbulence which is a highly nonlinear phenomenon in space and time. We have fabricated an array of 64-channel poloidal probes surrounding the linear cylindrical plasma named LMD-U in order to study turbulence properties, particularly the nonlinear mode couplings, in the domain of poloidal wave number and frequency. However, misalignments of probe tips produce spurious modes, which do not exist in the real plasma, to distort the precise wave number measurements. The paper presents the description of the 64-channel poloidal probe array with means to adjust the probe positions, with discussion on the effects of the misalignments on the wave number measurements.
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Nakano H, Fujisawa A, Shimizu A, Ohshima S, Iguchi H, Yoshimura Y, Minami T. Reconstruction method of local density fluctuation for heavy ion beam probe measurements. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2007; 78:063502. [PMID: 17614607 DOI: 10.1063/1.2745233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Heavy ion beam probe (HIBP) is an excellent diagnostic to measure the density and potential fluctuations simultaneously in magnetically confined plasmas. However, it has been well known that the density fluctuation measured with the HIBP is not local but contains the fluctuations along the beam orbits. In this article, a method is proposed to evaluate local density fluctuation in the HIBP measurements by removing the well-known path integral effects. The reconstructed density fluctuation amplitude and power spectrum are shown, for example, by applying the proposed method on the density fluctuation measurement data obtained in a toroidal helical plasma, Compact Helical System.
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Fujisawa A, Itoh K, Shimizu A, Nakano H, Ohshima S, Iguchi H, Matsuoka K, Okamura S, Minami T, Yoshimura Y, Nagaoka K, Ida K, Toi K, Takahashi C, Kojima M, Nishimura S, Isobe M, Suzuki C, Akiyama T, Nagashima Y, Itoh SI, Diamond PH. Experimental evidence of a zonal magnetic field in a toroidal plasma. PHYSICAL REVIEW LETTERS 2007; 98:165001. [PMID: 17501426 DOI: 10.1103/physrevlett.98.165001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Indexed: 05/15/2023]
Abstract
A zonal magnetic field is found in a toroidal plasma. The magnetic field has a symmetric bandlike structure, which is uniform in the toroidal and poloidal directions and varies radially with a finite wavelength of mesoscale, which is analogous to zonal flows. A time-dependent bicoherence analysis reveals that the magnetic field should be generated by the background plasma turbulence. The discovery is classified as a new kind of phenomenon of structured magnetic field generation, giving insight into phenomena such as dipole field generation in rotational planets.
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Okamura S, Akiyama T, Fujisawa A, Ida K, Iguchi H, Isobe M, Kado S, Minami T, Nagaoka K, Nakamura K, Nishimura S, Matsuoka K, Matsushita H, Nakano H, Ohshima S, Oishi T, Shimizu A, Suzuki C, Takahashi C, Toi K, Yoshimura Y, Yoshinu M. Improved Confinement and Related Physics Study in the Compact Helical System. FUSION SCIENCE AND TECHNOLOGY 2007. [DOI: 10.13182/fst07-a1286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Uehara M, Shibahara K, Fujita S, Tobita T, Ohba S, Fujisawa A, Nonaka M, Inokuchi T. Epithelioid hemangioendothelioma of tongue: A case report with immunohistochemical studies. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.ooe.2005.09.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Nonaka M, Ikeda H, Fujisawa A, Uehara M, Inokuchi T. Induction of apoptosis by paclitaxel in human oral carcinoma cells. Int J Oral Maxillofac Surg 2006; 35:649-52. [PMID: 16513327 DOI: 10.1016/j.ijom.2006.01.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2005] [Revised: 08/19/2005] [Accepted: 01/16/2006] [Indexed: 11/24/2022]
Abstract
The present study investigated induction of apoptosis in NB-1 oral carcinoma cells by paclitaxel and the expression of Bcl-2 and Bax in relation to this apoptotic cell death. Paclitaxel induced apoptotic cell death in NB-1 cells in a dose- and a time-dependent manner. The present results suggest that paclitaxel can induce apoptosis of NB-1 cells, which may be mediated by down-regulation of Bcl-2 together with up-regulation of Bax.
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Fujisawa A, Itoh K, Iguchi H, Matsuoka K, Okamura S, Shimizu A, Minami T, Yoshimura Y, Nagaoka K, Takahashi C, Kojima M, Nakano H, Ohsima S, Nishimura S, Isobe M, Suzuki C, Akiyama T, Ida K, Toi K, Itoh SI, Diamond PH. Identification of zonal flows in a toroidal plasma. PHYSICAL REVIEW LETTERS 2004; 93:165002. [PMID: 15524996 DOI: 10.1103/physrevlett.93.165002] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Indexed: 05/24/2023]
Abstract
This Letter presents experimental confirmation of the presence of zonal flows in magnetically confined toroidal plasma using an advanced diagnostic system--dual heavy ion beam probes. The simultaneous observation of an electric field at two distant toroidal locations (approximately 1.5 m apart) in the high temperature (approximately 1 keV) plasma provides a fluctuation spectrum of electric field (or flow), a spatiotemporal structure of the zonal flows (characteristic radial length of approximately 1.5 cm and lifetime of approximately 1.5 ms), their long-range correlation with toroidal symmetry (n=0), and the difference in the zonal flow amplitude with and without a transport barrier. These constitute essential elements of turbulence-zonal flow systems, and illustrate one of the fundamental processes of structure formation in nature.
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Yamamoto Y, Fujisawa A, Hara A, Dunlap WC. An unusual vitamin E constituent (alpha-tocomonoenol) provides enhanced antioxidant protection in marine organisms adapted to cold-water environments. Proc Natl Acad Sci U S A 2001; 98:13144-8. [PMID: 11687648 PMCID: PMC60838 DOI: 10.1073/pnas.241024298] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A new vitamin E constituent having an unusual methylene unsaturation at the isoprenoid-chain terminus of alpha-tocopherol (alpha-Toc) was isolated from chum salmon eggs and was found to have identical antioxidant activity as does alpha-Toc in methanol or liposomal suspension at 37 degrees C. Here we report that this marine-derived tocopherol (MDT) is broadly distributed with alpha-Toc in the tissue of marine fish, and that the MDT composition of total vitamin E is greater in the flesh of cold-water salmon (12-20%) than in that of tropical fish (< or =2.5%). Vitamin E analysis of cultured masu salmon maintained on a MDT-deplete diet showed substantially less MDT content than native masu salmon, suggesting a trophic origin of MDT. This contention is supported by the finding of MDT in marine plankton from the cold waters of Hokkaido. We found that MDT inhibited peroxidation of cholesterol-containing phosphatidylcholine liposomes to a greater extent than did alpha-Toc at 0 degrees C. Furthermore, the ratios of the rate constants for MDT and alpha-Toc to scavenge peroxyl radicals increased with decreasing rates of radical flux in liposomes and fish oil at 0 degrees C, indicating that the enhanced activity of MDT at low temperature is attributed to its greater rate of diffusion in viscous lipids. These results suggest that MDT production, or its trophic accumulation, may reduce lipid peroxidation in marine organisms functionally adapted to cold-water environments.
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Ikeda H, Kitamura A, Uehara M, Tobita T, Ohba S, Nonaka M, Fujisawa A, Inokuchi T. [A case of squamous cell carcinoma of the oral floor showing a complete response to oral administration of UFT]. Gan To Kagaku Ryoho 2001; 28:1929-31. [PMID: 11729490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
A 73-year-old male with squamous cell carcinoma of the oral floor (T1N0M0), who had not consented to radical treatment was treated with UFT by oral administration alone. After commencement of the administration, tumor remission was observed at 2 weeks and disappeared clinically at 8 weeks. The total period of oral administration of UFT was twenty-three months, and the total dose was 186.5 g as tegafur. Major adverse effects were pigmentation of hands and liver dysfunction. He remains under observation, and there is no evidence of tumor recurrence.
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Abstract
The blood-contacting surface, mainly composed of polycarbonate, of the Gyro C1E3 pump was modified using plasma glow discharge to introduce a carboxyl functional group, coated with a base layer of polyethyleneimine as a linker, and coupled with heparin by multi-ionic binding to enhance blood compatibility. A relative surface content of 3.7% sulfur, which demonstrated heparin immobilization on the polycarbonate substrate, was observed on x-ray photoelectron spectroscopy, and a initial bioactivity of approximately 88.5 +/- 7.3 mIU/cm2 was obtained by the chromogenic method for antifactor Xa assay. Furthermore, in vitro observation of platelet and fibrin adherence using bovine blood under dynamic flow conditions for 6 h revealed that the multi-ionically heparinized Gyro C1E3 had significantly stronger antithrombogenecity than the noncoated original type which was evaluated as a good hemocompatible blood pump for clinical use. Not only the Gyro C1E3 but also the ionically heparin-coated Gyro pump are expected to be thromboresistant in clinical use.
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Ida K, Minami T, Yoshimura Y, Fujisawa A, Suzuki C, Okamura S, Nishimura S, Isobe M, Iguchi H, Itoh K, Kado S, Liang Y, Nomura I, Osakabe M, Takahashi C, Tanaka K, Matsuoka K. Observation of toroidal flow antiparallel to the <E(r) x B(straight theta)> drift direction in the hot electron mode plasmas in the compact helical system. PHYSICAL REVIEW LETTERS 2001; 86:3040-3043. [PMID: 11290102 DOI: 10.1103/physrevlett.86.3040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2000] [Indexed: 05/23/2023]
Abstract
A toroidal flow antiparallel to the <E(r) x B(straight theta)> drift direction is observed in the hot electron mode plasmas when a large positive electric field and a sharp electron temperature gradient are sustained inside the internal transport barrier in the Compact Helical System. This toroidal flow reaches up to 5x10(4) m/s at the plasma center, and it is large enough to reverse the toroidal flow driven by a tangentially injected neutral beam. These observations clearly show the plasma favors flow in the minimum nablaB direction at the transport barrier.
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Abstract
PURPOSE To evaluate the clinical aspects of patients with primary cornea guttata and the specular microscopical findings/morphology in their corneal endothelial cells. METHODS Twenty-three patients consulting Kanazawa Medical University Hospital or related hospitals in Ishikawa or Fukui prefectures and diagnosed with primary cornea guttata by slit-lamp examination underwent an analysis of their clinical features and corneal endothelial cells. RESULTS Most cases were middle-aged to elderly women. None of them complained of visual impairment due to cornea guttata. The 46 eyes of these cases were included in this study. Specular microscopical findings revealed that the size and density of dark areas varied, with asymmetry noted in some cases. The parameters of the endothelial cells comprising mean cell area, the proportion of hexagonal cells, and the coefficient of variation, were almost within normal limits except for 1 eye of a 79-year-old man who was speculated to be at an early stage of Fuchs endothelial corneal dystrophy. Three cases had undergone cataract surgery, but did not show significant changes in endothelial morphology before and after surgery. In a statistical study on endothelial cell morphology, cell parameters except for minimal cell area correlated significantly with age. Although the density and size of dark areas correlated with each other, neither correlated with any of the cell parameters. CONCLUSION Cornea guttata does not lead to visual impairment or abnormalities in corneal endothelial cell parameters except for a small number of cases that must be considered to be at an early stage of Fuchs dystrophy.
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Takano T, Schulte-Eistrup S, Yoshikawa M, Nakata K, Kawahito S, Maeda T, Nonaka K, Linneweber J, Glueck J, Fujisawa A, Makinouchi K, Yokokawa M, Nosé Y. Impeller design for a miniaturized centrifugal blood pump. Artif Organs 2000; 24:821-5. [PMID: 11091172 DOI: 10.1046/j.1525-1594.2000.06630.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The impeller design for a miniature centrifugal blood pump is an important consideration since the small diameter impeller requires higher rotational speed, which may cause more blood trauma compared to the larger diameter impeller. Three different impeller vanes (straight vanes with a height of 4 mm and 8 mm, and 8 mm curved vanes) of which the diameter was 35 mm were subjected to hydraulic performance and hemolysis tests in the same pump housing. Both straight vane impellers attained left ventricular assist condition (5 L/min against 100 mm Hg) at 2,900 rpm while the curved vane required 3,280 rpm. There was no significant hemolysis difference between the tall and short vanes. The curved impeller vanes did not exhibit sufficient hydraulic performance when compared to the straight vanes. The straight vane impellers, even with different heights, were incorporated into the same pump housings, and the vane heights did not drastically change the hydraulic performance or hemolysis.
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Nakata K, Yoshikawa M, Takano T, Maeda T, Nonaka K, Linneweber J, Kawahito S, Glueck J, Fujisawa A, Makinouchi K, Yokokawa M, Nosé Y. Gyro pump wear and deformation analysis in vivo study: creep deformation. Artif Organs 2000; 24:653-5. [PMID: 10971256 DOI: 10.1046/j.1525-1594.2000.06596.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Gyro pump has a double pivot bearing system to support its impeller. In this study, the integrity of the bearing system was examined after ex vivo studies. The pumps were implanted into calves and evaluated for different periods as a paracorporeal left ventricular assist device (LVAD). One pump was subjected to a test of 30 days, 1 for 15 days, 4 for 14 days, 1 for 10 days, 1 for 7 days, 2 for 4 days, and 4 for 2 days. One additional pump was subjected to percutaneous cardiopulmonary support (PCPS) condition for 6 days (total pressure head 500 mm Hg with a pump flow rate of 3 L/min). The anticoagulation treatment consisted of a continuous administration of heparin to maintain an achieved clotting time (ACT) of 200-250 s during the LVAD study and 250-300 s during the PCPS study. After the experiment, the pumps were disassembled, and the wear and deformation of male and female bearings were analyzed. There were no dimensional changes on male bearings but there were on female bearings. Wear and deformation of the female bearings were calculated as follows: wear and deformation = (depth of female before pumping) - (depth after pumping). Thirteen assembled Gyro pumps were disassembled to measure the depth of the female bearings before pumping. There was no statistical relationship between the wear and deformation and the motor speed x driving period. From these results, the deformation was not due to wear but to the creep or elastic deformation. This study suggested that the double pivot bearing system of the Gyro pump is highly durable.
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Nakata KI, Yoshikawa M, Takano T, Sankai Y, Ohtsuka G, Glueck J, Fujisawa A, Makinouchi K, Yokokawa M, Nosaka S, Nose Y. Control system for an implantable rotary blood pump. Ann Thorac Cardiovasc Surg 2000; 6:242-6. [PMID: 11042480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
Rotary blood pumps can be used for long-term left ventricular assist devices. These pumps have several advantages over the conventional pulsatile pumps including smaller size, higher efficiency, and simple design and construction. However, one of the difficulties associated with the rotary blood pump is the proper control method to maintain an optimum flow rate in different physiological conditions. The rotary blood pump can be controlled by two methods. The first is to utilize the measured pump flow rate from its servo signal. The second is to detect and avoid abnormal pumping conditions such as; back flow and sudden increase in the pressure head. This abnormal situation typically occurs from excessive suction of blood when there is a functional or mechanical occlusion in the inflow cannula. The ultrasound flow meter is durable and reliable but it is difficult to continually monitor the blood flow rate of an implantable pump. Therefore, another method is needed instead of the continuous flow monitoring. One chronic calf having an LVAD was subjected for the development of this control system. This calf survived more than 6 months. Voltage, current, motor speed, heart rate and the pump flow rate were recorded and stored at 30-min intervals in a computer. Utilizing these parameters, attempts were made (1) to achieve indirect flow assessments and (2) to reveal abnormal operating parameters of the centrifugal pump (1). Indirect flow measurement, the predicted pump flow rate was calculated from these pump derived parameters (required power, motor speed and heart rate). The value of the coefficient of determination (R) between the measured and estimated pump flow rate was 0.796. (2) Abnormal operating indicator, there was an association between the required current and pump flow waves. The current was differentiated, and then calculated to the power of the differentiated current. The normal range of this value was 0.02+/-0.54. In abnormal conditions, this abnormal operating indicator increased 500 times. The predicted flow estimation method and abnormal operating indicator were available from intrinsic operating parameters of the pump and need no sensors. These two methods were simple, yet they are possibly effective and reliable servo control methods for a rotary blood pump.
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