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Biomedical subjects

N Takenaka

Publications and source records attributed to N Takenaka.

At least 19 recordsLinked to original sources
PubMed2004

Image processing methods to obtain symmetrical distribution from projection image.

Flow visualization and measurement of cross-sectional liquid distribution is very effective to clarify the effects of obstacles in a conduit on heat transfer and flow characteristics of gas-liquid two-phase flow. In this study, two methods to obtain cross-sectional distribution of void fraction are applied to vertical upward air-water two-phase flow. These methods need projection image only from one direction. Radial distributions of void fraction in a circular tube and a circular-tube annuli with a spacer were calculated by Abel transform based on the assumption of axial symmetry. On the other hand, cross-sectional distributions of void fraction in a circular tube with a wire coil whose conduit configuration rotates about the tube central axis periodically were measured by CT method based on the assumption that the relative distributions of liquid phase against the wire were kept along the flow direction.

Journal Article↗
PubMed2004

Visualization and void fraction measurement of gas-liquid two-phase flow in plate heat exchanger.

Adiabatic and boiling gas-liquid two-phase flows in a simulated plate heat exchanger with a single-ribbed channel were visualized by a thermal neutron radiography method. In the experiments under adiabatic condition, the air-water two-phase flows in an aluminum test section were visualized. In the boiling two-phase flow experiments, chlorofluorocarbon R141b was used as the working fluid. Two-dimensional distributions of void fraction were measured from visualized images via some image processing techniques. As a result, it was shown that both the phases tended to flow straight in the ribbed channel, and mixing of gas and liquid phases was weak. Moreover, when working fluids flew into the test section as a gas-liquid mixture, the phase distributions were strongly affected by a liquid pool at the test section inlet.

Journal Article↗
PubMed2004

Quantitative flow visualization of fluidized-bed heat exchanger by neutron radiography.

Quantitative flow visualization of a gas-solid fluidized-bed installed vertical tube-bank has been successfully conducted using neutron radiography and image processing technique. The quantitative data of void fraction distribution as well as the fluctuation data are presented. The time-averaged void fraction is well correlated by the drift-flux model. The bubbles formed in the bed, rise along the vertical tubes and the observed bubble size is smaller than that in a free bubbling bed without tube-banks. The bubble diameter is well correlated by the modified Mori and Wen's correlation taking into account the pitch of tube arrangement. The bubble rise velocity is also well correlated by applying the drift-flux model. These results are consistent for both bed materials of Geldart's B- and A-particles, while the bubble size is significantly different between two kinds of particles.

Journal Article↗
PubMed2001

[Acute subdural abscess due to mixed infection of Eikenella corrodens and Streptococcus constellatus].

Eikenella corrodens is a gram-negative, facultative anaerobic rod that frequently exists as part of normal human flora in the upper respiratory tract and gastrointestinal tract. Recently, E. corrodens is reported as a rare causative agent of empyematic lesion. We report a case of 10-year-old girl with acute subdural abscess. She developed a high grade fever, swelling of the left periorbital area, right sided partial seizure and hemiplegia. Brain CT and MRI showed left parietal subdural abscess. Because intravenous antibiotic therapy was not effective enough and her neurological symptoms progressed, surgical drainage was performed in order to decompress the brain and to determine the causative agents. Through careful bacterial cultures, E. corrodens and Streptococcus constellatus were detected from the subdural abscess. After the drainage operation and a three week course of appropriate chemotherapy, the abscess completely disappeared and no sequela remained.

Acute Disease↗
PubMed2001

Measurement of dissolved oxygen based on enhanced cerium(IV) chemiluminescence.

The reaction of Ce(IV) with pyrogallol caused chemiluminescence, which was enhanced by dissolved oxygen. Dissolved oxygen in water was able to help in the determination by enhancing the chemiluminescence intensity. The limit of detection calculated from 3sigma was 43 micromol/dm3, and the relative standard deviation was 1.2% at 613 micromol/dm3 (n = 5). The results obtained for natural and tap water samples were compared with those provided by conventional methods; the agreement between them corroborated the usefulness of the proposed method. The chemiluminescence mechanism was studied by examining the effect of interference with Cl- and measuring the chemiluminescence spectrum. The chemiluminescence emitter, however, could not be identified.

Calibration↗
PubMed2001

Trace level determination of low-molecular-weight alcohols in aqueous samples based on alkyl nitrite formation and gas chromatography.

A simple and sensitive method for the determination of liquid methanol and ethanol at trace levels by an alkyl nitrite formation reaction has been established. Alcohol was allowed to react with nitrous acid, which was yielded from sulfuric acid and sodium nitrite in the solution, to form the corresponding alkyl nitrite in the hexane organic phase. Alkyl nitrites in hexane were analyzed by a gas chromatograph with an electron capture detector (GC-ECD). The detection limits, which were determined at a signal-to-noise ratio of 3, were 1.1 and 0.7 micrograms/L for methanol and ethanol, respectively, by 1 microL injection. The relative standard deviations for n = 8 were 4.0 and 3.3% for methanol and ethanol, respectively. The method was applied to determine the alcohol concentration in a rice paddy, pond water, tap water, and well water. Those aqueous samples were also spiked with standard alcohols; the average recoveries of spiked methanol and ethanol were 98 and 91% with relative standard deviations of 6.1 and 4.0%, respectively.

Journal Article↗
PubMed2001

Chemiluminescence method with potassium permanganate for the determination of organic pollutants in seawater.

A chemiluminescence method with potassium permanganate was developed for use as an indicator of organic pollutants in fresh water. This method could be applied to the determination of organic pollutants in seawater as well. However, the flow chemiluminescence method suffered from the interference of chloride ions at the same concentration of seawater because of the production of manganese dioxide in the oxidation of chloride ions with permanganate. The conditions (concentrations of potassium permanganate and sulfuric acid and sample volume, i.e. flow injection method) were chosen to minimize the interference of chloride ions. The chemiluminescence method shows a good correlation with the chemical oxygen demand method on fresh water added artificial sea salt and seawater samples. Natural seawater was analyzed by the chemiluminescence method. The results obtained were compared with those obtained by chemical oxygen demand under the alkaline condition and total organic carbon methods. The chemiluminescence method has higher sensitivity and reproducibility than the conventional chemical oxygen demand and total organic carbon methods.

Chromatography, Liquid↗
PubMed2001

[A case of Mycobacterium intracellulare infection complicated by immotile cilia syndrome].

A 25-year-old woman with a history of immotile cilia syndrome (ICS) was admitted to our hospital with dyspnea. Chest roentgenography revealed dense infiltrates in both lower lung fields in addition to bronchiectasis and small nodular opacities, which had been observed previously. Transbronchial lung biopsy demonstrated evidence of non-caseating epithelioid cell granuloma. Sputum specimens were examined, and isolates were identified as Mycobacterium intracellulare. The patient was given antituberculous therapy and clarithromycin, which induced clinical improvement. It is well known that bronchial mucociliary transport is severely impaired in patients with ICS. However, to our knowledge, cases of M. intracellulare infection complicated by ICS have not been reported in Japan. We must pay close attention to the concurrence of these diseases.

Adult↗
PubMed2000

Flow analysis method for determining the concentration of methanol and ethanol in the gas phase using the nitrite formation reaction.

This paper presents a flow determination method for low molecular weight alcohols (methanol, ethanol) in the gas phase using the nitrite formation reaction, which was developed from an earlier method using a glass bottle. In this method, the ambient air and nitrogen dioxide (1,000 ppmv) were allowed to continuously flow in a glass tube, which had been filled with 10 g of Pyrex glass beads. The flow rates of the ambient air and nitrogen dioxide were 30 and 20 cm3/min, respectively. The gas-phase alkyl nitrites produced by the dark reaction of atmospheric alcohols and nitrogen dioxide on the Pyrex glass beads were then analyzed by gas chromatography with an electron capture detector. The alcohol concentrations of the samples were calculated using a calibrated conversion factor for each alcohol to its nitrite. The detection limits for the methanol and ethanol are 0.7 and 0.5 ppbv, respectively. This flow method was used to determine the atmospheric alcohol concentrations and was found to have the advantages of a short sampling time and simple quantitative procedure compared with the previously reported method (glass bottle method). The feasibility of this method was also established.

Journal Article↗
PubMed1999

Real-time imaging of glucocorticoid receptor dynamics in living neurons and glial cells in comparison with non-neural cells.

To investigate the intracellular trafficking of glucocorticoid receptor (GR) in response to various conditions in a single living cell, a green fluorescent protein (GFP) and rat GR chimera construct (GFP-GR) was prepared. We transiently transfected GFP-GR into primary cultured rat hippocampal neurons, cortical glial cells, and non-neural cells, e.g. COS-1 cells and CV-1 cells, and compared the dynamic changes in subcellular localization of GFP-GR in these cells. When GFP-GR was expressed in the cells, GFP-GR efficiently transactivated the mouse mammary tumour virus promoter in response to dexamethasone (DEX). The cytoplasm-to-nuclear translocation of GFP-GR induced with 10(-7) m DEX, a specific agonist of GR, at 37 degrees C was completed within 30 min in all cell types used, and the rate of nuclear translocation was dependent on the ligand dose. The translocation of GFP-GR into the nucleus from the cytoplasm was induced in a ligand-specific manner, similar to that of the native GR. The disruption of microtubules by colchicine or nocodazole showed no significant effect on the DEX-induced GFP-GR translocation from the cytoplasmic region to the nuclear region. The cells were not deteriorated during time-lapse imaging analysis for 1 h at 37 degrees C. The present findings suggest that the subcellular localization of GFP-GR is dynamically changed in response to extracellular and intracellular conditions, and that there are no conspicuous variations in the manner of trafficking of GR among different types of cells in vitro.

Animals↗
PubMed1997

[Accumulation of 14C-cystine in inherited cataractous rat lens].

This study was designed to investigate the formation of mixed disulfides of protein and glutathione (GSH) in the cataractous lens. We compared the changes in accumulation of 14C-cystine in cultured inherited cataractous rat lens (ICR/f) during cataractogensis with those in Wistar strain rats. The accumulation of 14C-cystine in water insoluble protein (WIP) of the lens was increased, especially in lens recognized cataract. The radioactivity accumulated in the WIP was released by incubation with 2-mercaptoethanol (2-ME), dithiothereitol (DTT) and GSH. The accumulation of 14C-cystine in WIP was inhibited by pretreatment with DTT. The existence of some materials in the lens-which combined with S-S compounds became clear. A large part of the materials is present in WIP which is increased along with the lens opacification. We surmised that the accumulation of 14C-cystine was related to the reaction of protein-glutathione disulfide (PSSG).

Aging↗
PubMed1996

[Primary intramedullary melanocytoma of medulla oblongata: a case report].

A case of intramedullary melanocytoma of the medulla oblongata; which has not been hitherto reported, is presented. The tumor ran on a slow progressive course. The patient died of pneumonia seven months after the operation. MRI findings did not specify this tumor as they were not distinct from those of malignant melanoma. The tumor was totally black and was not attached to the dura. Microscopically, the neoplastic cells were uniform in size and possessed abundant melanin granules in their cytoplasm. Mitosis was very rare. The ultrastructure of the tumor cells showed many melanosomes at varying stages of maturation. The melanocytoma in the eloquent region has an unfavorable outcome.

Brain Neoplasms↗
PubMed1996

[Proton MR spectroscopy findings in herpes simplex encephalitis].

Localized proton magnetic resonance spectroscopy (1H-MRS) was conducted in two patients with herpes simplex virus type I encephalitis (HSE). MR spectra of bilateral temporal lobes were acquired by the single voxel method using 1.5T unit. Peaks indicating N-acetyl aspartate (NAA), choline (Cho) and creatine including phosphocreatine (Cr) were identified and ratios of NAA/Cr and Cho/Cr were calculated. These ratios were compared with those of the contralateral side showing normal MRI findings and also with the control spectra obtained from normal volunteers. Three abnormal findings were observed in the spectra of the patients suffering from HSE; 1. significant reduction of the NAA/Cr ratio at the involved temporal lobe, 2. mild reduction of the NAA/Cr ratio at the normal temporal lobe, and 3. elevation of the Cho/Cr ratio at the bilateral lobes, but more significant on the involved sides. These results indicated that neural loss and gliosis occurred in the contralateral area with normal MR images as well as the involved hemisphere. We concluded that 1H-MRS is able to show the specific histological findings of herpes simplex encephalitis. This is the first report assessing 1H-MRS for patients with HSE in Japan.

Aged↗
PubMed1994

Determination of trace amounts of urea by using flow injection with chemiluminescence detection.

Reaction between urea and hypobromite in alkaline solution was found to produce chemiluminescence with a maximum wavelength at 510 nm. A simple chemiluminescence detection method was used for the determination of urea in human urine and natural aqueous samples, which combined this chemiluminescence reaction with a flow injection analysis system. The relative standard deviation for 5 x 10(-7) mol dm-3 urea is 1.9% (n = 6), and the detection limit is 9.0 x 10(-8) mol dm-3 (3Sr). As this chemiluminescence reaction is very fast, a double concentric tube mixer connected directly to the chemiluminescence cell was used to mix urea solution and hypobromite solution. Alkylamines, carboxylic acids and most amino acids do not interfere in the determination. Ammonium ion interferes, but the sensitivity for ammonium ion is only 1% of that for urea. The interference from ammonium ion was removed sufficiently by using an on-line cation-exchange column.

Flow Injection Analysis↗
PubMed1990

Interpeduncular high-density spot in severe shearing injury.

Thirty cases of severe shearing injury were analyzed utilizing serial computed tomography scans and clinical observations. Fatalities occurred in the majority of patients whose Glasgow Coma Scale scores at admission were 6 or less. The presence of perimesencephalic subarachnoid hemorrhage, hemorrhage in the corpus callosum, acute brain swelling, and intraventricular hemorrhage on computed tomography scans resulted in high mortality rates. In 13 patients, interpeduncular high-density spots were observed on computed tomography scans, which were performed in the acute stage of injury. Eight of these patients died, and those surviving had poorer neurological outcomes than corresponding patients with identical Glasgow Coma Scale scores on admission. In the management of severe shearing injury patients, more attention should be given to the presence of interpeduncular high-density spots as well as other important diagnostic computed tomography findings regarding diffuse brain injury.

Adolescent↗
PubMed1989

[A case of pseudotumor cerebri associated with colon cancer].

A case of pseudotumor cerebri associated with iron deficiency anemia due to colon cancer is reported in a 37-year-old woman. Her initial symptoms were vomiting and severe headache. On physical examination, no lymph nodes and abdominal mass were palpable but marked anemia was noted in her skin and conjunctiva . Neurological examination revealed papilledema in her both eyes and stiff neck. There was no abnormal findings on CT scan on admission. Spinal puncture revealed CSF pressure as high as 620 mmH2O with normal cells, protein, sugar and chloride levels. Hematological examination revealed iron deficiency anemia and thrombocytosis. Angiography at third day revealed no sinus occlusion, but retention of contrast media was seen on the cortical vein of parietal lobe and right transverse sinus. Brain scintigram at sixth day revealed mild accumulation in left parietal lobe, so small venous infarction was suggested. There were two circumscribed stenotic lesions of right ascending colon in the barium enema, and right hemicolectomy was achieved. The pathological diagnosis was adenocarcinoma. The symptoms of pseudotumor cerebri was completely disappeared soon after the surgery together with resolution of anemia. She lives with no deficits now 1 year 3 months after surgery. In conclusion much attention is necessary to a patient of pseudotumor cerebri with iron deficiency anemia for the presence of cancer, because not only this central nervous system lesion is reversible and curable but also the cancer itself may be curable by surgery.

Adenocarcinoma↗