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K Shibuya

Publications and source records attributed to K Shibuya.

At least 19 recordsLinked to original sources
PubMed2006

Photoemission from buried interfaces in SrTiO3/LaTiO3 superlattices.

We have measured photoemission spectra of SrTiO3/LaTiO3 superlattices with a topmost SrTiO3 layer of variable thickness. A finite coherent spectral weight with a clear Fermi cutoff was observed at chemically abrupt SrTiO3/LaTiO3 interfaces, indicating that an "electronic reconstruction" occurs at the interface between the Mott insulator LaTiO3 and the band insulator SrTiO3. For SrTiO3/LaTiO3 interfaces annealed at high temperatures (approximately 1000 degrees C), which leads to Sr/La atomic interdiffusion and hence to the formation of La(1-x)Sr(x)TiO3-like material, the intensity of the incoherent part was found to be dramatically reduced whereas the coherent part with a sharp Fermi cutoff was enhanced due to the spread of charge. These important experimental features are well reproduced by layer dynamical-mean-field-theory calculation.

Journal Article↗
PubMed2006

Local switching of two-dimensional superconductivity using the ferroelectric field effect.

Correlated oxides display a variety of extraordinary physical properties including high-temperature superconductivity and colossal magnetoresistance. In these materials, strong electronic correlations often lead to competing ground states that are sensitive to many parameters--in particular the doping level--so that complex phase diagrams are observed. A flexible way to explore the role of doping is to tune the electron or hole concentration with electric fields, as is done in standard semiconductor field effect transistors. Here we demonstrate a model oxide system based on high-quality heterostructures in which the ferroelectric field effect approach can be studied. We use a single-crystal film of the perovskite superconductor Nb-doped SrTiO3 as the superconducting channel and ferroelectric Pb(Zr,Ti)O3 as the gate oxide. Atomic force microscopy is used to locally reverse the ferroelectric polarization, thus inducing large resistivity and carrier modulations, resulting in a clear shift in the superconducting critical temperature. Field-induced switching from the normal state to the (zero resistance) superconducting state was achieved at a well-defined temperature. This unique system could lead to a field of research in which devices are realized by locally defining in the same material superconducting and normal regions with 'perfect' interfaces, the interface being purely electronic. Using this approach, one could potentially design one-dimensional superconducting wires, superconducting rings and junctions, superconducting quantum interference devices (SQUIDs) or arrays of pinning centres.

Journal Article↗
PubMed2006

Retroperitoneal hemorrhage due to bilateral adrenal metastases from lung adenocarcinoma.

A 56-yr-old man was admitted to our university hospital for severe back pain one month after a resection for lung adenocarcinoma (stage IIIA) without evidence of the adrenal mass. Computed tomography (CT) of the abdomen showed bilateral bleeding of adrenal tumors. Endocrinological laboratory studies showed high plasma ACTH and normal serum cortisol levels with the loss of circadian rhythm. Although plasma ACTH levels increased, there was no cortisol response to administration of human corticotropichormone (hCRH). Core-needle biopsy was performed on the right adrenal tumor and revealed adenocarcinoma cells mimicking a primary lung tumor previously examined. We diagnosed retroperitoneal hemorrhage due to bilateral adrenal gland metastasis from lung adenocarcinoma with adrenal insufficiency. Adrenal metastases most commonly originate from a primary lung tumor, followed by stomach, esophagus and liver/bile ducts. Bilateral adrenal metastases were noted in approximately half of all adrenal metastases patients. Clinically significant adrenal hemorrhage by metastasis is exceedingly rare and non-specific symptoms, such as abdominal, chest or back pain, nausea and vomiting, confusion, weakness, hypotension, shock and high fever, are often observed in these patients. We present a case of massive retroperitoneal hemorrhage and adrenal insufficiency due to adrenal gland metastasis from adenocarcinoma of lung.

Adenocarcinoma↗
PubMed2006

Transbronchial fine needle aspiration cytological examination: a useful tool for diagnosing primary lung cancer.

BACKGROUND: Obtaining a definitive preoperative diagnosis plays a critical role in deciding upon the treatment approach for lung carcinoma. However, success in making definitive diagnoses of small primary lung cancers will require new approaches because these cancers are difficult to detect using standard biopsy procedures. METHODS: We evaluated the results of morphologic definitive diagnosis together with various clinical factors in 1003 primary lung cancers resected surgically. Patients underwent transbronchial brushing, fine needle aspiration cytology, forceps biopsy, and/or forceps biopsy-stamp cytology for preoperative diagnoses, in conjunction with the use of Diff-Quik to confirm that hits had been made on the radiographic shadows before terminating the examinations. RESULTS: Sensitivities of the diagnostic procedures for primary lung cancers were as follows: 64.8% for brushing, 56.1% for transbronchial forceps biopsy, 72.0% for transbronchial forceps biopsy-stamp cytology, and 86.4% for transbronchial fine needle aspiration. The four transbronchial biopsy procedures had a combined overall sensitivity of 92.7%. In patients with peripheral lung cancers of 2 cm or less in diameter, transbronchial fine needle aspiration had a sensitivity of 75.9%, which was the highest sensitivity for all transbronchial examinations. In the subset of 296 patients who underwent all four transbronchial biopsy examinations, transbronchial fine needle aspiration had the highest sensitivity of preoperative diagnosis of all the transbronchial examination methods. CONCLUSIONS: The sensitivity of preoperative cytological diagnosis for primary lung cancers, especially transbronchial aspiration cytology, is high. Transbronchial fine needle aspiration cytology is useful for the preoperative diagnosis of primary lung cancer.

Adolescent↗
PubMed2006

[Mediastinal recurrence of breast cancer suspecting mediastinal fibrosis].

A 63-year-old female, who had undergone a modified radical mastectomy for breast cancer at the age of 45, was suffered from trachyphonia due to left recurrent nerve paralysis at the age of 53. She presented left phrenic nerve paralysis and dysphagia at the age of 61. Computed tomography (CT) revealed mediastinal fibrosis, stenosis of esophagus and superior vena cava, and slight lymph nodes swelling. Video-assisted thoracoscopic mediastinal biopsy was performed and the mediastinal fibrosis was diagnosed as recurrence of breast cancer 17 years after the breast cancer operation. She underwent mediastinal radiation and chemotherapy for mediastinal recurrence and stenting for esophageal stenosis.

Biopsy↗
PubMed2005

Frequency of loss of heterozygosity at 3 p, 9 p, 13 q, and 17 p is related to proliferative activity in smokers with stage I non-small cell lung cancer.

BACKGROUND: Tumor cells of lung cancer exhibit genetic abnormalities as well as high proliferative activity. The purpose of this study was to evaluate the relationship of genetic abnormalities and smoking status, histological type, and tumor proliferative activity in resected samples of stage I non-small cell lung cancer (NSCLC). METHODS: We evaluated 126 samples of stage I NSCLC from patients who underwent complete resection between 1988 and 1993. Loss of heterozygosity (LOH) was assessed using primers that amplified polymorphic microsatellite markers at D3S1300, D3S643, D3S1317, D9S171, IFNA, D13S153, and TP53. Expression of Ki-67 nuclear antigen was examined using immunohistochemical methods to assess tumor proliferative activity. RESULTS: The Fractional Regional Loss index (FRL) was significantly higher in squamous cell carcinoma samples than in adenocarcinoma samples (p < 0.0001). In smokers, Ki-67 labeling index (LI) in high-FRL cases was significantly higher than in low-FRL cases (p < 0.0001). CONCLUSION: The frequency of LOH at 3 p, 9 p, 13 q, and 17 p was related to proliferative activity in smokers with stage I non-small cell lung cancer.

Carcinoma, Non-Small-Cell Lung↗
PubMed2005

A comparison of video and autofluorescence bronchoscopy in patients at high risk of lung cancer.

The aim of this study was to compare the diagnostic yield of flexible video bronchoscopy (FVB) and autofluorescence bronchoscopy (i.e. lung imaging fluorescence endoscopy (LIFE)) in 151 patients at a high risk of lung cancer and with moderate dysplasia or worse on sputum cytology mass screening. Findings from FVB and LIFE were classified as either normal, abnormal or suspicious for cancer. Endobronchial biopsies (EBX) were obtained from abnormal or suspicious areas on FVB and/or LIFE, or randomly when FVB and LIFE were normal. Moderate dysplasia and worse were defined as pathologically positive. Overall, 83 out of 343 (24%) EBX were pathologically positive. The sensitivity of FVB was 72% and LIFE 96%. Relative sensitivity of LIFE over FVB was 1.33. Specificities of FVB and LIFE were 53 and 23%, respectively. The numbers of pathologically positive EBX from sites designated normal, abnormal or suspicious were: from FVB, 23 out of 162 (14%), 37 out of 151 (25%) and 23 out of 30 (77%); from LIFE, three out of 69 (4%), 44 out of 212 (21%) and 36 out of 62 (58%). In normal or abnormal areas at FVB, there was a significant increase in the yield of EBX guided by abnormal and suspicious sites noted at LIFE. In conclusion, endobronchial biopsies of suspicious findings from lung imaging fluorescence endoscopy and flexible video bronchoscopy have a good diagnostic yield. Lung imaging fluorescence endoscopy is more useful when flexible video bronchoscopy is either normal or abnormal.

Adult↗
PubMed2005

[Imaging aid for thoracoscopic thymectomy; thymic vein visualization].

The spread and progress of thoracoscopic surgery has been remarkable. There are many important organs and blood vessels in the mediastinal space, thus, as inadvertent injury invites serious consequences, it is necessary to understand the anatomical position of existing structures. When enucleating the thymoma under a thoracoscope, one of the blood vessels to be careful about is the thymic vein. Therefore, we examined whether the thymic vein could be confirmed using a multidetector-row computed tomography (MD CT). We believed we could understand the anatomical position of the thymic vein by analyzing the high resolution slice data provided in MD CT using a work station. The diameter of the thymic is from a little less than 1 mm to 3 mm, and there were individual variations in position and the number of the vein. The thymic vein flowed into the left brachiocephalic vein in many cases. In some cases, the thymic vein flowed into the right internal thoracic vein or superior vena cava. It appears that visualization of the thymic vein could provide useful data when performing thoracoscopic thymectomy.

Adult↗
PubMed2004

Detailed mapping of the ERG-ETS2 interval of human chromosome 21 and comparison with the region of conserved synteny on mouse chromosome 16.

We have carried out a detailed annotation of 550 kb of genomic DNA on human chromosome 21 containing the ERG and ETS2 genes. Comparative genomic analysis between this region and the interval of conserved synteny on mouse chromosome 16 indicated that the order and orientation of the ERG and ETS2 genes were conserved and revealed several regions containing potential conserved noncoding sequences. Four pseudogenes including those for small protein G, laminin receptor, human transposase protein and meningioma-expressed antigen were identified. A potentially novel gene (C21orf24) with alternative mRNA transcripts, consensus splice donor and acceptor sites, but no coding potential nor murine orthologue, was identified and found to be expressed in a range of human cell lines. We have identified four novel splice variants that arise from a previously undescribed 5' exon of the human ERG gene. Comparison of the cDNA sequences enabled us to determine the complete exon-intron structure of the ERG gene. We have also identified the presence of noncoding RNAs in the first and second introns of the ETS2 gene. Our studies have important implications for Down syndrome as this region contains multiple mRNA transcripts, both coding and potentially noncoding, that may play as yet undescribed roles in the pathogenesis of this disorder.

Alternative Splicing↗
PubMed2004

A new automatic device for measuring the spinnbarkeit of saliva: the Neva Meter.

OBJECTIVES: We have recently developed a new device for measuring the spinnbarkeit of saliva called the Neva Meter. The purpose of this study was to evaluate this device and to measure spinnbarkeit as well as viscosity, another important property, in the resting saliva of 24 healthy adults. METHODS: We used polyvinyl alcohol (PVA) as a standard solution to establish the reproducibility of spinnbarkeit tests. We collected resting saliva from 24 employees of a business office (16 males and 8 females, average age: 37.8) and investigated the relationship between spinnbarkeit and viscosity. RESULTS: The spinnbarkeit of PVA increased along with the concentration of the solution, and the reproducibility of the values was acceptable. Spinnbarkeit of resting saliva showed a positive correlation with viscosity at a shear rate of 76.6 s(-1) (r = 0.55, P < 0.05) and 191.5 s(-1) (r = 0.59, p < 0.05). CONCLUSIONS: The newly developed Neva Meter was suitable for measuring the spinnbarkeit of saliva quickly and easily at the chair-side in the dental clinic. Results obtained using this new device may be important for understanding and evaluating the condition of the oral cavity.

Adult↗
PubMed2004

Clinicopathological analysis of clinical N0 peripheral lung cancers with a diameter of 1 cm or less.

BACKGROUND: The appropriateness of limited resection for small-sized lung cancer continues to be debated. It is not yet clear whether tumor size alone is a reliable indicator for limited resection. METHODS: From 1980 to 2002, 27 patients with clinical N0 peripheral lung cancers having diameters of 1 cm or less underwent pulmonary resection. Clinicopathological features of these cases were reviewed retrospectively. RESULTS: Histological analysis showed that there were 23 cases of adenocarcinoma (81.5 %), two large cell carcinomas (7.4 %), and two carcinoid tumors. Twenty-two cases were classified as pathological stage 1, one was stage II, and four were stage III. Four patients (14.8 %) had lymphatic vessel invasion, three (11.1 %) had lymph node metastasis, and two (7.4 %) had intrapulmonary metastasis. The 5-year disease-free survival rate was 76.6 %. CONCLUSIONS: It is impossible to predict the effectiveness of an intentional limited resection for lung cancer using only tumor size.

Adenocarcinoma↗
PubMed2004

Development of a phantom compatible for MRI and hyperthermia using carrageenan gel-relationship between T1 and T2 values and NaCl concentration.

The authors developed a phantom, designated as the CAGN phantom, compatible for MRI and hyperthermia that is useful in the fundamental studies of non-invasive MR thermometry. The ingredients of this phantom are carrageenan, GdCl3 as a T1 modifier, agarose as a T2 modifier, NaCl as a conductivity modifier, NaN3 as an antiseptic and distilled water. Another phantom that was developed, the CAG phantom, has relaxation times that are adjustable to those of any human tissue. To use this phantom for electromagnetic heating, NaCl was added to change the conductivity of the phantom and clarified the relationship between the conductivity and NaCl concentration. This study examined the relationship between relaxation times and NaCl concentration of the CAGN phantom. The results showed that both T1 and T2 values were affected by NaCl and the experimental results led to the empirical formulae expressing the relationship between the relaxation rates (1/T1, 1/T2) and the concentrations of GdCl3, agarose and NaCl. The appropriate concentrations of T1 and T2 modifiers were calculated from these empirical formulae when making a specified phantom that has the required relaxation times and NaCl concentration.

Algorithms↗
PubMed2004

Development of a phantom compatible for MRI and hyperthermia using carrageenan gel--relationship between dielectric properties and NaCl concentration.

A phantom has previously been developed containing carrageenan, agarose and gadolinium chloride (called CAG phantom) for MRI with 1.5 T. T(1) and T(2) relaxation times of this phantom are independently changeable by varying concentrations of relaxation-time modifiers to simulate relaxation times of the various types of human tissues. The CAG phantom has a T(1) value of 202-1904 ms and a T(2) value of 38-423 ms, when the GdCl(3) concentration is varied from 0-140 micromol/kg and the agarose concentration is varied from 0-1.6%. A new phantom has now been developed (called CAGN phantom), made by adding an electric conductive agent, NaCl, to the CAG phantom for use in the areas of MRI and hyperthermia research. Dielectric properties of the CAGN phantom were measured and the results of experiments were expressed by the Cole-Cole equation in the frequency range of 5-130 MHz. The relationship between the conductivity of the CAGN phantom and the concentration of NaCl was expressed by a linear function in the frequency range of 1-130 MHz. The linear function involves a parameter of frequency and, when the frequency is 10 MHz, the conductivity of the CAGN phantom can be changed from 0.27-1.26 Sm(-1) by increasing the NaCl concentration from 0-0.7%. The CAGN phantom developed can be employed in basic experiments for non-invasive temperature measurement using MRI and as a loading phantom for MRI with up to 3 T.

Carrageenan↗
PubMed2004

Cerebral cortex activity during supramaximal exhaustive exercise.

AIM: The purpose of this study was to examine the effect of fatigue resulting from supramaximal dynamic exercise on cerebral cortex activity. METHODS: Five healthy male subjects (age 24.6+/-0.4 years, body weight 62.9+/-1.1 kg, height 175.3+/-1.2 cm, and maximal O2 uptake per body mass 48.4+/-1.3 ml/kg/min) participated in this study. All subjects performed at 120% of maximal oxygen uptake (VO2peak) on a cycle ergometer until reaching a state of volitional fatigue. Cerebral oxygenation was measured by near-infrared spectroscopy (NIRS) throughout the supramaximal constant exhaustive exercise. RESULTS: The mean exercise duration of the subjects was 147.2+/-3.4 s. The peak value of blood lactate concentration within 3-10 min after the exercise test was 14.4+/-0.1 mmol/l. Cerebral oxygenation (8.8+/-1.8 micromol/l) was increased significantly during the first minutes of exercise compared with the pre-exercise value (p<0.05) and cerebral oxygenation decreased with the passage of time during exercise. Cerebral oxygenation at the end of exercise decreased significantly compared with the resting value (-29.9+/-3.4 micromol/l, p<0.05). CONCLUSION: These findings suggest that the exhaustive exercise induces the decrease of cerebral function and that the fatigue resulting from dynamic exercise decreases the cerebral cortex activity.

Adult↗
PubMed2003

Distribution of Actinobacillus actinomycetemcomitans serotypes and Porphyromonas gingivalis in Japanese adults.

Strains of the bacterium Actinobacillus actinomycetemcomitans found in the human oral cavity are divided into five serotypes, a, b, c, d, and e. In this study, A. actinomycetemcomitans serotypes and Porphyromonas gingivalis were isolated from 656 subgingival sites in systemically healthy Japanese adults. A. actinomycetemcomitans was detected in 19.5% of 328 Japanese subjects, while 27.1% of subjects were positive for P. gingivalis. Of 75 A. actinomycetemcomitans-positive sites, only one serotype was detected in 39 sites (52.0%). The numbers of sites in which two different serotypes and three different serotypes were detected were 18 (25.0%) and 7 (9.3%), respectively. A. actinomycetemcomitans serotype c was detected more frequently in sites that were positive for both P. gingivalis and A. actinomycetemcomitans (76.9%) than in sites that were P. gingivalis-negative and A. actinomycetemcomitans-positive (33.9%). In addition, serotype c was detected much more frequently than the other serotypes (<16%) in sites that were positive for both P. gingivalis and A. actinomycetemcomitans. These findings suggest that the characteristics of serotype c may differ from those of the other serotypes. This report is the first to use PCR to describe the distribution of A. actinomycetemcomitans serotypes in humans and to examine the association between the distribution of A. actinomycetemcomitans serotypes and the presence of P. gingivalis.

Adult↗
PubMed2003

Unilateral ocular subalbinism in a laboratory Beagle dog.

Blue discoloration of the iris was found in the left eye of a male laboratory Beagle dog, which had a normal tricolor coat and clinically showed no visual impairment. Ophthalmoscopically, the affected eye revealed red-colored tigroid fundus, in which no tapetum was present. The retinal vasculature and the optic disc showed no noticeable changes. Histopathologically, in the left eye melanocytes had extremely few melanin granules in the anterior segment, including the anterior border layer, in the stroma and sphincter muscle of the iris and in the stroma of the ciliary body and choroid. However, the posterior pigment epithelium of the iris, the pigment epithelium of the ciliary body and the retinal pigment epithelium showed normal pigmentation. The tapetal elements were completely absent. Number and distribution of the S-100 protein-positive melanocytes with or without melanin granules in the iris, ciliary body and choroid of the left eye were similar to those of the normal right eye. Ultrastructurally, melanocytes in the anterior segment of the affected iris possessed no or few melanosomes which were incompletely melanized. In the right eye, no abnormal features were observed. Based on these results, the present case was diagnosed as unilateral ocular subalbinism with tapetal aplasia in a Beagle dog.

Albinism, Ocular↗
PubMed2003

High magnification bronchovideoscopy combined with narrow band imaging could detect capillary loops of angiogenic squamous dysplasia in heavy smokers at high risk for lung cancer.

BACKGROUND: We investigated the use of high magnification bronchovideoscopy combined with narrow band imaging (NBI) for the detailed examination of angiogenic squamous dysplasia (ASD). This was carried out in relation to bronchial vascular patterns with abnormal mucosal fluorescence in heavy smokers at high risk for lung cancer. METHODS: Forty eight patients with sputum cytology specimens suspicious or positive for malignancy were entered into the study. Conventional white light and fluorescence bronchoscopic examination was first performed. Observations by high magnification bronchovideoscopy with conventional white light were made primarily at sites of abnormal fluorescence, and then repeated with NBI light to examine microvascular networks in the bronchial mucosa. Spectral features on the RGB (Red/Green/Blue) sequential videoscope system were changed from the conventional RGB broadband filter to the new NBI filter. The wavelength ranges of the new NBI filter were B1: 400-430 nm, B2: 420-470 nm, and G: 560-590 nm. ASD tissues were also examined using a confocal laser scanning microscope equipped with argon-krypton (488 nm) and argon (514 nm) laser sources. RESULTS: The microvessels, vascular networks of various grades, and dotted vessels in ASD tissues were clearly observed in NBI-B1 images. Diameters of the dotted vessels visible on NBI-B1 images agreed with the diameters of ASD capillary blood vessels diagnosed by pathological examination. Capillary blood vessels were also clearly visualised by green fluorescence by confocal laser scanning microscopy. There was a significant association between the frequency of dotted vessels by NBI-B1 imaging and tissues confirmed as ASD pathologically (p=0.002). CONCLUSIONS: High magnification bronchovideoscopy combined with NBI was useful in the detection of capillary blood vessels in ASD lesions at sites of abnormal fluorescence. This may enable the discrimination between ASD and another pre-invasive bronchial lesion.

Adult↗