Publications by authors named "Akisada M"

A dendrimer with rigid branched terminal components was prepared by a copper-catalyzed Hüisgen 1,3-dipolar cycloaddition reaction. A zinc 5,15-diethynyl-10,20-bis(3,5-di- tert-butylphenyl)porphyrin unit was incorporated at the core of the dendrimer as a receptor site for an added pyridyl ligand. The appearance of an absorption band characteristic of the planar conformer of conjugated chains in the terminal components suggested that the dendrimer adopts a folded higher order structure in dichloromethane at 25 °C.

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A HARPICON(TM) camera has been applied to a digital angiography system with fluorescent-screen optical-lens coupling. It uses avalanche multiplication in the photoconductive layer for high-sensitivity imaging. The limiting spatial resolutions in the 1050 scanning-line mode of the camera are about 30 and 50 micro m at input field sizes of 20 x 20 and 50 x 50 mm on the screen, respectively.

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A serine protease neuropsin expressed in the hippocampus of adult brain has been implicated in synaptic plasticity. We report here that endogenous neuropsin was localized extracellularly in neuronal cell bodies and their neurites in mouse hippocampal cultures. Furthermore, we found that, in cultured mouse hippocampal neurons, recombinant neuropsin enhanced neurite projection from soma after 14 h of culture and neuronal aggregation with neurite fascicles at 48 h.

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Extracellular serine protease neuropsin (NP) is expressed in the forebrain limbic area of adult brain and is implicated in synaptic plasticity. We screened for endogenous NP inhibitors with recombinant NP (r-NP) from extracts of the hippocampus and the cerebral cortex in adult mouse brain. Two SDS-stable complexes were detected, and after their purification, peptide sequences were determined by amino acid sequencing and mass spectrometry, revealing that target molecules were serine proteinase inhibitor-3 (SPI3) and murinoglobulin I (MUG I).

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A high-sensitivity HARPICON camera was developed for medical X-ray imaging using a fluorescent screen. It is an avalanche-multiplication-type image pick-up tube and is 32 times more sensitive than conventional tubes. The camera also has a wider dynamic range than conventional medical-imaging cameras because a maximum output signal current of 2.

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Rationale And Objectives: For intravenous (i.v.) coronary arteriography, a real-time two-dimensional (2D) imaging system is being developed using above-K-edge monochromatic X-rays alone.

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Many radiologists and radiological technologists understand that Picture Archiving and Communication Systems (PACS) are useful not only for image management but also for improving the quality of patient care. However, such systems have not yet been widely installed in hospitals. In order to determine why radiologists have not installed a PACS in their hospitals, we carried out a written survey of 400 Japanese hospitals asking them to describe the current image management activities, the problems inherent in PACS and the problems related to standardization.

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PACS has been regarded as a system which will bring a new era to image handling, radiology departments and its services to other departments of the hospital. However, many recently held international conferences indicate that a worldwide consensus on 'what is PACS, why is PACS needed and who is PACS for' has not been established. Although the actual PACS implementation will vary among the countries and according to each situation, a worldwide consensus of PACS should be possible.

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To evaluate changes in muscle energetics following endurance training, we measured phosphorus-31 nuclear magnetic resonance (31P NMR) spectra on rat muscle in vivo before and after training in the same animals. The endurance training lasted for 3 months. The 31P NMR spectra were obtained serially at rest, during exercise by electrical stimulation, and during recovery.

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To investigate changes in left atrial morphology and dimensions during the cardiac cycle, the atrium was visualized by intravenous digital subtraction angiography (DSA). The study subjects consisted of 22 male patients whose average age was 54.5 +/- 8.

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In the University of Tsukuba, PACS research is being carried out with a special emphasis on the reporting system. The radiological diagnostic system in Japan is not sufficiently developed and the number of diagnostic radiologists in Japan is not as large as in many European countries (M. Akisada, Present status of PACS activities in Japan.

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The ingredients seem to exist for switching from film-based radiology to digital radiology utilizing the concept Picture Archiving and Communication System (PACS). Why has this not happened? What are the barriers limiting the diffusion of PACS into health care? This was the theme of the 1st Japan-Nordic Symposium in PACS, which was held in Tokyo, March 29-30, 1990. Over 40 radiologists and technical specialists in PACS participated.

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Balb/c mice were irradiated on the leg in the area of the spread out Bragg peak (SOBP) of a 30 MeV proton beam. The proton beam was modulated to different ranges in order to determine the early skin reaction versus beam quality at different portions of the SOBP. The respective 50% moist desquamation doses of 1, 3, and 8.

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A cine magnetic resonance (MR) imaging technique, involving the acquisition of kinematic sagittal images during knee movement, was used to evaluate 52 symptomatic knee joints. Results were compared with those obtained by means of static three-dimensional (3D) MR imaging. Twenty-seven of the 28 anterior cruciate ligament (ACL) tears and 22 of 24 normal ligaments were correctly identified at cine MR imaging for a sensitivity of 96% and a specificity of 92%.

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Regional cerebral perfusion was studied in three patients with the mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome, using single photon emission computed tomography (SPECT) with N-isopropyl-p-[123I]iodoamphetamine (IMP). Accumulation of the tracer was relatively decreased in the parietooccipital regions and also in the frontotemporal regions after stroke-like episodes. However, quantitative regional cerebral blood flow (rCBF) measurement showed that rCBF was relatively well preserved even at these sites, and a hyperemic state was observed at the sites of normal accumulation.

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Thirty arms of healthy adults were studied with MR imaging using surface coil. Fine structures of the arm, such as muscular bundles, small vessels and nerves were clearly demonstrated. Deep fascia dividing muscular bundles appeared as high intensity on T1-weighed image due to fat deposition beneath the fascia.

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We report a case of double primary malignancy, in which intracranial germinoma and thymoma occurred successively and independently. As curative therapies, the former lesion was treated by definitive irradiation and the latter by postoperative irradiation. Excellent local control has been maintained for 79 and 49 months, respectively, since the beginning of the radiotherapy.

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Magnetic resonance imaging (MRI) is superior to ultrasonography and X-CT especially in density resolution in soft tissue. 31P NMR provides information on metabolism, which has not been obtained in vivo by conventional methods, such as phosphocreatine (PCr), inorganic phosphate (Pi), ATP, and intracellular pH. We used MRI and 31P NMR spectroscopy to study skeletal muscle metabolism of human and rat.

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Synchrotron radiation is a broadspectrum intense X-ray beam. Selected X-ray wavelength was obtained by Bragg reflex. That is a monochromatic beam, which has a high spatial resolution, and has a K-edge discontinuity in attenuation coefficient, which, by energy subtraction, contributes to improve time resolution.

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Radiation tolerance of the partially irradiated liver was studied in eight patients with primary hepatoma treated by a multimodal approach. Seven patients were treated by transarterial embolization therapy (TAE) with Lipiodol-MMC, and two patients were treated by operation, combined with radiotherapy. Six patients had liver cirrhosis and the other one had renal dysfunction.

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A system for magnetic resonance imaging of the knee joint during movement was developed by using a gating system and cine acquisition. The technique was used in 10 subjects: five with no history of knee pain or injury and five with tears of the anterior cruciate ligament. The normal ligaments and menisci appeared as low-intensity structures against intermediate-intensity hyaline cartilage.

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Six patients with large invasive thymomas were treated by preoperative irradiation with 12 to 20 Gy before total or partial resection of the tumor. The responses of these 6 thymomas were estimated on the chest radiograms as follows; complete response in 2 patients, partial response in 3 and no response in one. Although the clinical responses varied, the surgical specimens of all the tumors pronounced severe fibrosis, probably not related to irradiation, and necrotic foci with a few viable tumor cells.

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MIPS Standard activities in Japan.

Med Inform (Lond)

August 1990

The Medical Image Processing System (MIPS) plan is a standard plan for the online communication of imaging data in Japan. The ACR-NEMA Standard is not always easy for manufacturers in Japan to comply with. This situation led to the formulation of MIPS Plan Minimum Set-87 (MIPS Standard-87), which uses reciprocal corresponding patterns to ACR-NEMA Standards.

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