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Biomedical subjects

Y Bando

Publications and source records attributed to Y Bando.

At least 19 recordsLinked to original sources
PubMed2006

Direct synthesis of B-C-N single-walled nanotubes by bias-assisted hot filament chemical vapor deposition.

Direct synthesis of large-scale ternary boron carbonitride single-walled nanotubes (BCN-SWNTs) via a bias-assisted HFCVD process was presented. The BCN-SWNTs were grown over the powdery Fe-Mo/MgO catalyst by using CH4, B2H6, and ethylenediamine vapor as the reactant gases. As high as 16 atom % nitrogen can be incorporated within the nanotube shells, with the boron content in the range of 2-4 atom %. The ternary covalent bonding nature of the BCN-SWNTs was well characterized, and the B, C, and N elemental maps were clearly imaged by energy-filtered transmission electron microscopy.

Journal Article↗
PubMed2006

Intrapatellar tendon lipoma with chondro-osseous differentiation: detection of HMGA2-LPP fusion gene transcript.

A 54 year old man developed an unusual lipoma in the patellar tendon, consisting of a fibro-adipose component and a chondro-osseous component. The fibro-adipose component contained mature adipocytes, lipoblasts, and fibroblasts; the chondro-osseous component showed typical endochondral bone formation. Molecular analysis showed that the identical HMGA2-LPP fusion transcript-characteristic of lipoma, parosteal lipoma, and pulmonary chondroid hamartoma-was detectable in the both components.

Adipogenesis↗
PubMed2005

Excellent field-emission properties of P-doped GaN nanowires.

GaN nanowires with P doping were synthesized via a simple thermal evaporation process. The P-doped GaN nanowires have average diameters of approximately 100 nm and lengths up to tens of micrometers. Scanning electron microscope and high-resolution field-emission transmission electron microscope analyses revealed that P doping results in a rough surface morphology of GaN nanowires. Field-emission measurements showed that P doping effectively decreases the turn-on field of GaN nanowire to 5.1 V/mum, holding promise of application as an electron emitter. The rough surface is responsible for enhancement of the field-emission properties of GaN nanowires.

Journal Article↗
PubMed2005

Production and characterization of single-crystal FeCo nanowires inside carbon nanotubes.

We describe the synthesis of novel monocrystalline FeCo nanowires encapsulated inside multiwalled carbon nanotubes (MWNTs). These FeCo nanowires exhibit homogeneous Fe and Co concentrations and do not contain an external oxide layer due to the presence of insulating nanotube layers. The method involves the aerosol thermolysis of toluene-ferrocene-cobaltocene solutions in inert atmospheres. The materials have been carefully characterized using state-of-the-art high-resolution transmission electron microscopy (HRTEM), electron-energy-loss spectroscopy (EELS), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), electron diffraction, HREELS-STM elemental mapping, X-ray powder diffraction, and SQUID magnetometry. We noted that the formation of FeCo alloys occurs at relatively low pyrolytic temperatures (e.g., 650-750 degrees C). These single-crystal nanowires, which have not been reported hitherto, always exhibit the FeCo (110) plane parallel to the carbon nanotube axis. The FeCo nanomaterials have shown large coercive fields at room temperature (e.g., 900 Oe). We envisage that these aligned ferromagnetic nanowires could be used in the fabrication of high-density magnetic storage devices and magnetic composites.

Cobalt↗
PubMed2004

A novel deletion mutation in the arginine vasopressin receptor 2 gene and skewed X chromosome inactivation in a female patient with congenital nephrogenic diabetes insipidus.

X-linked nephrogenic diabetes insipidus (NDI) is a rare inherited disorder caused by mutations in the arginine vasopressin receptor 2 (V2R) gene. The clinical phenotype is fully expressed in hemizygous male patients and is usually asymptomatic in heterozygous females. In the present study, a 51-yr-old Japanese female with congenital NDI and her family members were examined. The patient developed severe hypernatremia accompanied by hypoosmotic polyuria after gynecological surgery, and was unable to concentrate urinary osmolality in response to exogenous vasopressin. Direct sequencing analysis of the propositus and her two affected sons revealed a two-nucleotide deletion change at codon 30 (g.452-453delAC) in the V2R gene, resulting in a frameshift and premature termination in translation at codon 190. The X chromosome inactivation pattern was investigated in the propositus using methylation analysis of the polymorphic CAG repeat in the androgen receptor gene, and the value for relative X chromosome inactivation of one allele was 70.2%. In conclusion, we identified a novel V2R gene mutation in a female patient and her sons with congenital NDI, and her phenotype may be caused by skewed X chromosome inactivation.

Chromosomes, Human, X↗
PubMed2004

Inhibitory effects of Centella asiatica on azoxymethane-induced aberrant crypt focus formation and carcinogenesis in the intestines of F344 rats.

Effects of the water extract of Centella asiatica Linn. on formation of azoxymethane (AOM)-induced aberrant crypt foci (ACF) and intestinal tumorigenesis in male F344 rats were investigated. Treatment with the extract significantly decreased the number of larger ACF (with four or more crypts per focus) in the large intestine in the early stage, while the number of methylated DNA adducts was not decreased compared with that in the AOM-treated group. In the post-initiation stage, the extract significantly decreased the total number of ACF and the number of larger ACF, accompanied by a decrease in the 5-bromo-2'-deoxyuridine-labeling index and an increase in the induction of apoptotic cells in the colonic mucosa. The incidences of neoplasms, the numbers of adenocarcinomas in the small intestines and entire intestines, and sizes of neoplasms in the entire intestines in rats fed C. asiatica extract at a dose of 10 mg/kg were smaller than those in rats given AOM alone (p < 0.05). The extract at a dose of 100 mg/kg significantly reduced the multiplicity of neoplasms in the small intestine (p < 0.05). These results suggest that inhibition of the formation of AOM-induced ACF by C. asiatica extract is associated with modification of cell proliferation and induction of apoptosis in colonic crypts and that the extract has a chemopreventive effect on colon tumorigenesis.

Animals↗
PubMed2004

GRP94 reduces cell death in SH-SY5Y cells perturbated calcium homeostasis.

The endoplasmic reticulum (ER) resident-94 kDa glucose-regulated protein (GRP94), plays a pivotal role in cell death due to ER stress. In our study expression of GRP94 was increased in human neuroblastoma SH-SY5Y cells due to exposure to calcium ionophore A23187. A23187-mediated cell death was associated with activation of the major cysteine proteases, caspase-3 and calpain. Pretreatment with adenovirus-mediated antisense GRP94 (AdGRP94AS) reduced viability of SH-SY5Y cells subjected to A23187 treatment compared with wild type cells or cells with adenovirus-mediated overexpression of GRP94 (AdGRP94S). These results indicated that suppression of GRP94 is associated with accelerated cell death. Moreover, expression of GRP94 suppressed A23187-induced cell death and stabilized calcium homeostasis.

Amino Acid Chloromethyl Ketones↗
PubMed2002

New phases of sp2-bonded boron nitride: the 12R and 24R polytypes.

sp2-Bonded polytypes of graphite-like boron nitride are evidenced in the approximately twin-related bicrystal-like BN nanofibres synthesized by a high-temperature substitution reaction between carbon nanofibres and boron oxides in N2 atmosphere; the material shows a main 12R phase of A'ABC/C'CAB/B'BCA packing and a minor 24R phase with an A'ABC/BB'C'A'/C'CAB/ ... packing sequence.

Journal Article↗
PubMed2002

Synthesis and microstructural analysis of Si3N4 nanorods.

Alpha-Si3N4 nanorods with 20-80 nm width were synthesized by carbothermal reduction of SiO with amorphous activated carbon (AAC) as a reductant. Microstructural characterization of the synthesized nanorods was carried out by high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray analysis. Many Si3N4 nanorods were found to be twisted. Each twisted nanorod contained several straight Si3N4 parts. The straight parts had the rod axes orientated along the (1010) direction, which is the closest packing direction of alpha-Si3N4. There were two kinds of joints between the two adjacent straight Si3N4 parts. Formation mechanism of the Si3N4 nanorods is discussed.

Charcoal↗
PubMed2002

Non-autoimmune primary hypothyroidism in diabetic and non-diabetic chronic renal dysfunction.

The aim of this study was to investigate the frequency and mechanisms of hypothyroidism observed in diabetic patients with advanced diabetic nephropathy, including outcomes of management for this condition. A controlled study was designed using 32 diabetic and 31 non-diabetic patients not receiving hemodialysis or continuous ambulatory peritoneal dialysis (CAPD) who excreted mean urinary protein greater than 0.5 g/day examined on three consecutive days during admission to our hospital. Thyroid hormones in both serum and urine, anti-thyroid antibodies, renal function and iodine concentrations in serum were measured during admission in all patients included. In particular, in patients who showed overt hypothyroidism, further studies including large-needle biopsies of the thyroid and iodine-perchlorate discharge tests were performed. All patients in the two groups revealed negative antithyroid antibody titers, and the mean serum total iodine levels did not significantly differ between the two groups. Mean serum FT4 levels significantly decreased, and the TSH level was significantly elevated in the diabetic group compared to those in the non-diabetic group (p < 0.005, p < 0.02, respectively). The frequency of overt hypothyroidism in the diabetic group (22%; 7/32) was significantly higher (p < 0.05) than that in the non-diabetic group (3.2%; 1/31). The daily urinary thyroid hormone excretion in both groups did not show any significant correlation with serum thyroid hormone levels. Seven patients who revealed overt hypothyroidism in the diabetic group showed elevated serum total iodine levels during hypothyroidal status, ranging between 177 and 561 microg/l. Also, the iodine-perchlorate discharge tests carried out in six of these patients all showed a positive discharge. After management based on iodine restriction, normalization of serum thyroid hormone levels in accordance with definite decreases in the serum total iodine level was achieved, accompanied by a significant weight reduction. In conclusion, we found a significantly high prevalence of non-autoimmune primary hypothyroidism in patients with advanced diabetic nephropathy compared to those with non-diabetic chronic renal dysfunction, which may partly relate to earlier development of oedematous status. Clinical and laboratory findings suggest that impaired renal handling of iodine resulting in an elevation of serum iodine levels, rather than autoimmune mechanism or urinary hormone loss, may play a principal role in the development of these conditions, probably through a prolongation of the Wolff-Chaikoff effect. The mechanisms by which this phenomenon develops more frequently in diabetic than in non-diabetic renal dysfunction remain to be elucidated.

Aged↗
PubMed2001

Homologous phases built by boron clusters and their vibrational properties.

We have found a series of new rare earth boron-rich solids in REBC(N) (RE: Y, Ho, Er, Tm, and Lu), systems and their structures are solved from single crystal and/or powder X-ray diffraction data. Structure analysis results show that they are homologous with B(4)C and also show trigonal symmetry. As the two basic structural units, boron icosahedra and octahedra in the new phases form in layers and stack in different sequences which form different phases. With increasing number of icosahedral layers stacking between two neighboring octahedral layers, the c-axis of the unit cell is increased and the other two edges of the unit cell are only changed slightly. Three monophases of the series have been synthesized both in powders and as single crystals. The vibrational modes of the homologous phases are analyzed from the Raman spectra and compared with that of B(4)C.

Journal Article↗
PubMed2001

Hypothermic treatment restores glucose regulated protein 78 (GRP78) expression in ischemic brain.

Mild hypothermia is a well-known method of reducing brain damage caused by traumatic, hypoxic, and ischemic injury. To elucidate the neuroprotective mechanism induced by hypothermic treatment, we compared gene expression profiles in the hippocampus of gerbils rendered ischemic for 15 min and then reperfused for 3 h under conditions of normothermia (37+/-0.5 degrees C) or hypothermic treatment (34+/-0.5 degrees C). Using the differential display method, we observed significantly reduced expression of the 78 kDa glucose regulated protein (GRP78), in ischemic gerbil hippocampus that underwent normothermic reperfusion, but normal GRP78 expression in animals that underwent hypothermic reperfusion. In situ hybridization and Northern blot analysis showed GRP78 mRNA expression was reduced in the CA1 region of the hippocampus under normothermic conditions, but was not reduced under hypothermic conditions. Western blot analysis also showed the levels of immunoreactive GRP78 protein decreased in neurons of the hippocampal CA-1 region under normothermia, but not under hypothermic treatments. Furthermore, adenovirus-mediated overexpression of GRP78 protects rat hippocampal neurons from cell death and inhibits the rise in intracellular calcium concentration normally induced by hydrogen peroxide. These results suggest that reduction in GRP78 expression contributes to cell damage in the ischemic brain and that hypothermia-mediated restoration of GRP78 expression is one mechanism that enhances neuronal survival.

Amino Acid Sequence↗
PubMed2001

Papillary carcinoma of the thyroid with distant metastases to the cerebrum: a case report.

Cerebral metastases from papillary carcinoma of the thyroid are a very uncommon condition, but such metastases behave more aggressively and show poor prognosis. These metastases almost always involve concomitant lung or bone metastases which may be the first metastatic sites. Here we report a 53-year-old man with diffuse goiter and cervical lymphadenopathy who developed symptoms of elevated intracranial pressure. Computed tomography demonstrated ring-enhanced lesions showing a severe mass effect in the right cerebrum and a nodule in the right thyroid gland accompanied by swollen lymph nodes. Biopsied specimens of the thyroid nodule demonstrated malignant cells of papillary carcinoma. Surgical excision of the metastatic brain lesions was followed by total thyroidectomy with regional lymphadenectomy. Histological examinations confirmed that the patient had cerebral metastases from papillary carcinoma of the thyroid without other distant metastasis. Neurological abnormality disappeared after surgery and treatment with radioactive iodine (131I) and oral thyroxine were initiated thereafter. This case suggests that the thyroid gland is potentially a primary source of metastatic brain carcinoma. Moreover, early detection of cerebral metastases is crucial because these metastatic lesions can be life threatening, in contrast to the relatively less severe clinical course of this malignancy unless it is associated with any distant metastasis.

Brain Neoplasms↗
PubMed2001

Temperature dependency of radiation damage in inorganic materials by 300 keV electrons.

Temperature dependency of radiation damage in albite and natrolite was studied quantitatively by measuring the diffraction intensity with imaging plates. Radiation damage was reduced at low temperature in albite but was enhanced in natrolite. A damage process model, in which creation and annihilation of localized defects were considered, was proposed. According to this model, Boltzmann factor in temperature dependency is dominated by a difference between energy for diffusion of the localized defects and energy for breakdown of a crystal framework. When the diffusion energy is larger than breakdown energy, the activation energy in Boltzmann factor seems to be effectively negative.

Journal Article↗
PubMed2001

Nanotubes of boron nitride filled with molybdenum clusters.

Carbon nanotubes are known to be metallic or semiconducting, depending on their helicity and diameter. However, boron nitride (BN) nanotubes are the only nanotubular product known to date that are predicted to have stable insulating properties that are independent of their atomic structure and morphology. Thus, the BN tube has attracted prime attention as an advanced nanoinsulating shield for all types of encapsulated conducting material, i.e., metal wires, clusters, etc. However, so far there have been no successes in controlled one-dimensional filling of BN nanotubes with conductive material. We report the first experimental results on the synthesis, high-resolution transmission electron microscopy, energy dispersion X-ray analysis, and electron energy loss spectroscopy of BN nanotubes that are filled with Mo clusters over their entire length. This was accomplished by means of two-step thermochemical treatment of chemically vapor-deposited C nanotubes with B2O3, CuO, and MoO3 oxides in a flowing N2 atmosphere. The first examples of BN nanotubes filled with molybdenum clusters are reported and the formation of the first nanocable (approximately 10 nm in length), consisting of a conductive metal core and an insulating BN nanotubular shield is demonstrated.

Boron Compounds↗
PubMed2001

Painless thyroiditis associated with severe inflammatory reactions in amyloid goiter: a case report.

We report the case of a 64-year-old woman with rheumatoid arthritis (RA) associated with high grade fever, malaise, and painless swelling of thyroid gland. Laboratory findings showed severe systemic inflammatory reactions, including increases in various cytokines such as IL-6. Gallium-67 citrate imaging revealed intense uptake in the painlessly enlarged thyroid gland. Histologically, biopsied specimens of thyroid showed diffuse amyloid infiltrations, which included amyloid A (AA) protein. Biopsies of rectum and stomach revealed similar amyloid depositions, indicating that the amyloid had a secondary origin, potentially due to RA. All clinical symptoms were relieved by intravenous pulsatile administration of methylprednisolone followed by oral prednisone, resulting in prolonged hypothyroid status. To our knowledge, this is the first case report in Japan describing painless thyroiditis with severe inflammatory reactions in amyloid goiter.

Amyloid↗