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Biomedical subjects

Y Utsumi

Publications and source records attributed to Y Utsumi.

At least 19 recordsLinked to original sources
PubMed2003

Kondo effect in quantum dots coupled to ferromagnetic leads.

We study the Kondo effect in a quantum dot coupled to ferromagnetic leads and analyze its properties as a function of the spin polarization of the leads. Based on a scaling approach, we predict that for parallel alignment of the magnetizations in the leads the strong-coupling limit of the Kondo effect is reached at a finite value of the magnetic field. Using an equation of motion technique, we study nonlinear transport through the dot. For parallel alignment, the zero-bias anomaly may be split even in the absence of an external magnetic field. For antiparallel spin alignment and symmetric coupling, the peak is split only in the presence of a magnetic field, but shows a characteristic asymmetry in amplitude and position.

Journal Article↗
PubMed2001

Self-sterilizing and self-cleaning of silicone catheters coated with TiO(2) photocatalyst thin films: a preclinical work.

TiO(2) photocatalysts were successfully coated on silicone catheters or medical tubes by pretreatment of the silicone surface with a sulfuric acid solution (5 M) for 3 h. The TiO(2) film adhered to the silicone substrate strongly against tensile and bending stresses. On the TiO(2)-coated silicone-catheters under UV illumination, both the bleaching of methylene blue dye and the photocatalytic bactericidal effect on Escherichia coli (E. coli) cells were confirmed. Thus, this type of catheter can be sterilized and cleaned simply by irradiation with low-intensity UV light and can, therefore, be useful in the protection from catheter-related bacterial infections.

Coated Materials, Biocompatible↗
PubMed2000

Direct colorimetric method for determination of organophosphates in human urine.

A simple and sensitive method for determination of organophosphorus pesticides in human urine was developed by detecting the color complexes which resulted from reactions of organophosphorus pesticides and 4-(4-nitrobenzyl)pyridine (NBP) in urine. Based on studies of reaction conditions, e.g. reaction temperature and time, and reagent concentration, a colorimetric method was established. A 0.1-ml volume of NBP (45% in acetone) was added to a 1.0-ml volume of a urine sample, and the mixture was heated at 100 degrees C for 20 min. After cooling, 0.1 ml of tetraethylenepentamine was added. The organophosphorus pesticides showed a characteristic purplish blue color and the coloring complexes which were produced were stable for several hours. Furthermore, these complexes could be determined spectrophotometrically. The detection limits were 0.10-10 microg/ml in urine. The required time for analysis was approximately 30 min for one sample. Comparing the result of the proposed method with those of the GC-MS method, the results were similar for the 12 poisoning cases studied. Thus, the proposed method is useful for detection of these pesticides in critical care practices.

Chelating Agents↗
PubMed2000

Acute transient pseudoatrophy of the brain accompanying measles infection.

Two infants, age 1 year, with acute encephalopathy who showed transient pseudoatrophy of the brain were reported. They each had measles infection, followed by 'mild drowsiness'. Reversible brain atrophy has been observed in patients with undernutrition, dehydration, and overdoses of steroids and valproic acid. However, these manifestations were very mild and there was no history of drug administration in our patients. The cause of the transient brain pseudoatrophy was unknown. However, activation of glial cells accompanying the measles infection was thought to be one possibility to see high value of neopterin (51 pmol/l) in the cerebrospinal fluid in one case. Although 'mild drowsiness' is not a rare manifestation in patients with measles infection, it is probable that their 'mild drowsiness' is caused by acute encephalopathy like in our cases. Thus, we recommend that computed tomography scanning or magnetic resonance imaging is performed in patients showing 'mild drowsiness' during measles infection.

Acute Disease↗
PubMed1999

The Progression of Cavitation in Earlywood Vessels of Fraxinus mandshurica var japonica during Freezing and Thawing.

For an examination of the progression of cavitation in large-diameter earlywood vessels of a deciduous ring-porous tree, potted saplings of Fraxinus mandshurica var japonica Maxim. were frozen and then thawed. The changes in the amount and distribution of water in the lumina of the current year's earlywood vessels during the course of the freezing and thawing were visualized by cryo-scanning electron microscopy. When samples were frozen, most of the current year's earlywood vessels were filled with water. After the subsequent thawing, the percentage of cavitated current-year earlywood vessels gradually increased with time. All of the current year's earlywood vessels were cavitated within 24 h, and only limited amounts of water remained in the lumina of earlywood vessels. Similar cavitation of earlywood vessels was observed after thawing of frozen, excised stem pieces. In contrast, many vessels of the current year's latewood retained water in the lumina during freezing and thawing. These observations indicate that the cavitation of the current year's earlywood vessels is not produced during freezing but progresses during rewarming after freezing in F. mandshurica var japonica.

Journal Article↗
PubMed1999

[Morphologic features of ulcerative colitis].

Ulcerative colitis(UC) is an ulcero inflammatory disorder of unknown etiology affecting only the mucosa and submucosa of colon and, with Crohn's disease, is included in the term idiopathic inflammatory bowel disease. The macroscopic and microscopic features vary according to the stage of the disease process, and an acute phase and a chronic or resolving phase can be recognized. The main differential diagnosis of UC is with colorectal Crohn's disease. The most feared long-term complication of UC is cancer. The progression of UC to carcinoma is closely associated with dysplasia arising in multiple sites. The dysplastic changes should be distinguished from the epithelial changes resulting from regenerative atypia, and the evaluation of these changes is difficult. P53 immunohistochemical staining is helpful in confirming the presence of dysplasia. Molecular events in colorectal carcinogenesis of UC may be somewhat different from those of so-called adenoma-carcinoma sequence.

Colitis, Ulcerative↗
PubMed1998

A beamline for photochemical processes at atmospheric pressure.

A beamline especially designed for atmospheric photochemical reactions has been constructed at the NTT synchrotron radiation facility. By inserting a buffer helium chamber with Be and Si(3)N(4) partition windows between the beamline and the reaction chamber, studies can be performed without the differential pumping systems normally used in existing photochemistry beamlines. The reaction chamber is equipped with a gas supply system and analysis systems to investigate gas-phase and surface reactions. Purging using dry purified gases in combination with water-bubbling gives effective control of water concentration in the reaction chamber.

Journal Article↗
PubMed1998

Synchrotron-radiation-induced formation of salt particles on an X-ray lithography mask.

The suppression and removal of contaminants on X-ray masks are required for the application of X-ray lithography to practical semiconductor production, because contamination is easily transferred to the replicated resist patterns and degrades the LSI patterns. In order to study contamination of a Ta/SiN X-ray mask, its growth process was investigated using an atmospheric reaction chamber and in situ observation apparatus for gases at atmospheric pressure. It was found that the contamination particles were ammonium sulfate and oxalate. The sources of the salt particle were also identified.

Journal Article↗
PubMed1998

Visualization of cavitated vessels in winter and refilled vessels in spring in diffuse-porous trees by cryo-scanning electron microscopy

Xylem cavitation in winter and recovery from cavitation in the spring were visualized in two species of diffuse-porous trees, Betula platyphylla var. japonica Hara and Salix sachalinensis Fr. Schm., by cryo-scanning electron microscopy after freeze-fixation of living twigs. Water in the vessel lumina of the outer three annual rings of twigs of B. platyphylla var. japonica and of S. sachalinensis gradually disappeared during the period from January to March, an indication that cavitation occurs gradually in these species during the winter. In April, when no leaves had yet expanded, the lumina of most of the vessels of both species were filled with water. Many vessel lumina in twigs of both species were filled with water during the period from the subsequent growth season to the beginning of the next winter. These observations indicate that recovery in spring occurs before the onset of transpiration and that water transport through twigs occurs during the subsequent growing season. We found, moreover, that vessels repeat an annual cycle of winter cavitation and spring recovery from cavitation for several years until irreversible cavitation occurs.

Journal Article↗
PubMed1997

MR imaging in Guillain-Barré syndrome.

MRI in a 5-year-old girl with Guillain-Barré syndrome showed marked enhancement of nerve roots in the region of the conus medullaris and cauda equina. This enhancement gradually disappeared after high-dose immunoglobulin therapy. This characteristic finding of MRI may have diagnostic utility and represent the clinical course of the disease.

Cauda Equina↗
PubMed1997

Magnetic resonance imaging of the cauda equina in two patients with Guillain-Barré syndrome.

The results are presented of magnetic resonance imaging (MRI) of the spine in two cases of childhood Guillain-Barré syndrome. After injection of gadolinium-diethylenetriamine pentaacetic acid, MRI showed enhancement of the cauda equina in these patients. These MRI observations may help confirm the diagnosis of Guillain-Barré syndrome. The nerve root enhancement resolved as the clinical symptoms improved. Serial imaging may be useful in monitoring the response to therapy and assessing new treatment regimens. It may also yield a better understanding of the disease process.

Cauda Equina↗
PubMed1994

Breaks in the pars plicata following surgery for atopic cataract.

Two cases involving retinal detachment caused by breaks in the pars plicata of the ciliary body are presented. In both, retinal detachment developed following surgery for atopic cataract. The residual lens capsules contracted with evidence of fibrotic change. Nonpigmented ciliary epithelium appeared to have become detached and torn by traction through the zonules of Zinn.

Adult↗
PubMed1991

Effect of 17 beta-estradiol on the growth of an estrogen receptor-positive human esophageal carcinoma cell line.

Receptors for estrogen and for androgen in the nucleus and cytosol (ERn, ERc, ARn, and ARc, respectively) were studied on two newly established human esophageal carcinoma cell lines, ES-25C and ES-8C. ES-25C was ERn+ (the binding content 4.0 fmol/mg protein, Kd 0.09 nM), ERc-, ARn-, and ARc-. No receptors were found in ES-8C. Various doses of 17 beta-estradiol (E2) were added in vitro to investigate its effect on the growth of these cell lines. No effect of E2 was observed on ER--ES-8C cell line. The growth of ES-25C cell was significantly inhibited at the doses of 10(-10) and 10(-12) mol/l E2 compared with the control. The doubling time of 10(-12) mol/l E2-treated cells was 32 hours whereas that of control was 20 hours. This slower growth was reflected in the deduction of cells in S-phase utilizing 5-bromo 2'-deoxyuridine (BrdU) labeling. The current results strongly suggest that the growth inhibition of ER+ esophageal cancer cell by E2 is mediated by signal transduction induced by the estrogen-estrogen receptor system.

Aged↗
PubMed1991

Acute ascending necrotizing myelitis in Okinawa caused by herpes simplex virus type 2.

A case of rapidly progressing ascending myelitis was necropsied. Necrosis was present throughout the whole length of the spinal cord and involved both the grey and white matter randomly. The perivascular lymphocytic infiltration in the spinal cord in the present case was more pronounced than that in the previously reported two cases of necrotizing myelopathy associated with malignancy. Using immunoperoxidase staining the presence of herpes simplex virus type 2 (HSV 2) antigen was demonstrated. Electron microscopic examinations revealed large numbers of HSV particles in the spinal cord. HSV 2 may be a common aetiological agent of necrotizing myelopathy and myelitis in Okinawa, an HSV 2 endemic area. In the present case, the necrosis was mainly found in the spinal cord but was also observed, to a very limited extent, in the brain.

Acute Disease↗
PubMed1990

[Immunoglobulin class and light chain type of oligoclonal bands in CSF in children with CNS infectious diseases].

Agarose gel electrophoresis and immunofixation of CSF and serum from 16 patients aged from 1 day to 13 years with CNS infectious diseases (5 with purulent meningitis, 5 with aseptic meningitis, 4 with acute encephalitis, 1 with subdural empyema and 1 with SSPE) revealed oligoclonal IgG bands in 10 cases. In 4 cases, a high CSF/serum albumin ratio was recognized without an increase of IgG-index, probably representing a systemic immune response. Neither IgA nor IgM bands were recognized. IgG light chain was examined in 7 cases and IgG kappa bands predominated in 6 cases. IgG lambda bands predominance presented in only one case. Free IgG kappa or lambda chain was not found. These results suggested that the measurement of not only IgG-index but oligoclonal bands may have a diagnostic usefulness to know about local production of immunoglobulins in CSF.

Adolescent↗
PubMed1989

Role of estrogen receptors in the growth of human esophageal carcinoma.

In order to investigate the role of estrogen receptors (ER) in the growth of human esophageal carcinoma, tumor tissues of ER-positive but androgen receptor (AR)-negative line of squamous cell carcinoma (ES-8) were transplanted in ten male and ten female nude mice. As control, those of a tumor line without both receptors (ES-13) derived from human esophageal cancer were used. The growth rates of transplanted tumors were estimated up to 5 weeks. The tumor growth of ES-8 line was significantly greater in males than it was in females. Such a difference was not observed for ES-13 line. Moreover, in order to investigate the effect of estrogen on the ER, tumor tissues of ES-8 line were transplanted in six oophorectomized female mice, and next, estradiol (E2) (500 micrograms/kg, 50 micrograms/kg, or none) was administered to five transplanted female mice of each group, respectively. The growth rates of tumors were enhanced in oophorectomized female mice, and significantly suppressed with the physiologic dose (50 micrograms/kg) of E2 compared to the control. The current results seem to indicate that the inhibitory effect of estrogen on the tumor line is mediated by ER.

Animals↗