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T Sakakibara

Publications and source records attributed to T Sakakibara.

At least 19 recordsLinked to original sources
PubMed2006

Metallic spin-liquid behavior of the geometrically frustrated Kondo lattice.

Strongly frustrated magnetism of the metallic pyrochlore oxide Pr2Ir2O7 has been revealed by single crystal study. While Pr 4f moments have an antiferromagnetic RKKY interaction energy scale of /T*/ = 20 K mediated by Ir 5d-conduction electrons, no magnetic long-range order is found except for partial spin freezing at 120 mK. Instead, the Kondo effect, including a lnT dependence in the resistivity, emerges and leads to a partial screening of the moments below /T*/. Our results indicate that the underscreened moments show spin-liquid behavior below a renormalized correlation scale of 1.7 K.

Journal Article↗
PubMed2005

Plasminogen activator inhibitor-1 as a potential marker for the malignancy of colorectal cancer.

To test the hypothesis that plasminogen activator inhibitor-1 (PAI-1) may serve as a candidate marker for the malignancy of colorectal cancer (CRC), we performed a quantitative RT-PCR for PAI-1 gene and evaluated the possible relationship between PAI-1 gene expression levels and clinicopathological findings in CRC. A significant increase in PAI-1 expression scores was observed in lymph node metastasis-positive CRCs (2.19 +/- 0.43) compared to negative ones (0.35 +/- 0.42) (P = 0.0037) as well as in distant metastasis-positive CRCs (3.50 +/- 1.18) compared to negative ones (0.99 +/- 0.30). The PAI-1 expression score markedly increased with the tumour stage (P = 0.0063; ANOVA test). Moreover, multivariate analysis revealed the PAI-1 expression score to be a strong and independent prognostic factor for CRC (P = 0.0432). These results suggested that PAI-1 might serve as a new parameter for the prediction of prognoses in CRC.

Adult↗
PubMed2005

Metamagnetic quantum criticality revealed by 17O-NMR in the itinerant metamagnet Sr3Ru2O7.

We have investigated the spin dynamics using 17O-NMR in the bilayered perovskite Sr3Ru2O7, which sits close to a metamagnetic quantum critical point. The nuclear spin-lattice relaxation rate divided by temperature 1/T1T is enhanced on approaching the metamagnetic critical field of approximately 7.9 T, and at the critical field 1/T1T continues to increase and does not show Fermi-liquid behavior down to 0.3 K. The temperature dependence of T1T in this region suggests the critical temperature Theta to be approximately 0 K, which is strong evidence that the spin dynamics possesses a quantum critical character. Comparison between uniform susceptibility and 1/T1T reveals that antiferromagnetic fluctuations instead of two-dimensional ferromagnetic fluctuations dominate the spin fluctuation spectrum at the critical field, which is unexpected for itinerant metamagnetism.

Journal Article↗
PubMed2005

Observation of modulated quadrupolar structures in PrPb3.

Neutron diffraction measurements have been performed on the cubic compound PrPb(3) in a [001] magnetic field to examine the quadrupolar ordering. Antiferromagnetic components with q = (1/2 +/- delta 1/2 0), (1/2 1/2 +/- delta 0) (delta approximately 1/8) are observed below the transition temperature T(Q) (0.4 K at H = 0) whose amplitudes vary linear with H and vanish at zero field, providing the first evidence for a modulated quadrupolar phase. For H < 1 T, a nonsquare modulated state persists even below 100 mK suggesting quadrupole moments associated with a Tau(3) doublet ground state to be partially quenched by hybridization with conduction electrons.

Journal Article↗
PubMed2005

[Intrapulmonary aberrant needle; report of a case].

Intrapulmonary aberrant needles are rarely encountered in clinical practice. An intrathoracic aberrant needle should be always surgically removed as soon as possible. We report a case of an intrapulmonary aberrant needle removed with video-assisted thorascopic surgery (VATS) and briefly review the literature. A 47-year-old man referred to us for chest discomfort was found to have an intrapulmonary aberrant needle at the right middle lobe by chest X-ray and computed tomography (CT). We tried simple extraction under thoracoscopy, but a residual fragment was recognized by intraoperative X-ray after the removal of the needle from the surface of the lung. We searched for the residual fragment by real-time fluoroscopic examination. Partial resection was performed to remove the residual needle fragment at the right lower lobe. The postoperative course was uneventful and the man was discharged on the postoperative day 10. Intraoperative chest X-ray is always necessary before closing the chest to avoid leaving the residual fragments in the lung. The real-time fluoroscopy is useful to search for the residual fragment.

Foreign Bodies↗
PubMed2004

Disorder-sensitive phase formation linked to metamagnetic quantum criticality.

Condensed systems of strongly interacting electrons are ideal for the study of quantum complexity. It has become possible to promote the formation of new quantum phases by explicitly tuning systems toward special low-temperature quantum critical points. So far, the clearest examples have been appearances of superconductivity near pressure-tuned antiferromagnetic quantum critical points. We present experimental evidence for the formation of a nonsuperconducting phase in the vicinity of a magnetic field-tuned quantum critical point in ultrapure crystals of the ruthenate metal Sr3Ru2O7, and we discuss the possibility that the observed phase is due to a spin-dependent symmetry-breaking Fermi surface distortion.

Journal Article↗
PubMed2003

Magnetic field induced sign reversal of the anomalous Hall effect in a pyrochlore ferromagnet Nd2Mo2O7: evidence for a spin chirality mechanism.

The anisotropic Hall effect and magnetization have been investigated for single crystals of Nd2Mo2O7 under high magnetic fields up to 27 T and at low temperatures down to 50 mK. The magnetization curves indicate that the Nd moments with strong Ising anisotropy are coupled antiferromagnetically with the Mo spins and show field-induced flipping on the respective sites. The Hall resistivity changes its sign with increasing field applied along the [111] direction, while it monotonously approaches zero with the field applied along the [100] or [110] direction. This behavior is in accord with the prediction by the Berry phase theory and is interpreted in terms of the field-induced reversal of spin chirality on the pyrochlore lattice.

Journal Article↗
PubMed2003

Observation of a liquid-gas-type transition in the pyrochlore spin ice compound Dy2Ti2O7 in a magnetic field.

Low temperature magnetization measurements on the pyrochlore spin ice compound Dy2Ti2O7 reveal that the ice-rule breaking spin flip, appearing at H approximately 0.9 T applied parallel to the [111] direction, turns into a novel first-order transition for T<0.36 K which is most probably of a liquid-gas type. T-linear variation of the critical field observed down to 0.03 K suggests the unusual situation that the entropy release across the transition remains finite [approximately 0.5 (J/K) x mol-Dy] as T-->0, in accordance with a breaking of the macroscopic degeneracy in the intermediate "kagomé ice" state.

Journal Article↗
PubMed2002

[Subglottic granuloma with extubating mini-trach II: report of a case].

A case of subglottic granuloma after extubating Mini-trach II is described. The patient went aorto-coronary bypass and Mini-trach II was inserted for suction of sputum. Mini-trach II was extubated 6 days after insertion. The patient complained of dyspnea 3 months later. Examination showed subglottic granuloma. First, we burned the granuloma by laser under local anesthesia. Because the visual field was not good due to vocal cord movement, we failed to resect the granuloma completely. Therefore, we performed laryngo microsurgery under general anesthesia and resected the granuloma perfectly. The patient is in good health without signs of recurrence 6 months after granuloma removal. When we used Mini-trach II, the most important issues are insertion to the cricothyroid membrane, preventing infection, and careful follow-up after removing the Mini-trach II.

Aged↗
PubMed2001

Sugar-pendant diamines.

A set of 1,3-propanediamine derivatives connected to carbohydrates (5) has been prepared in four steps from peracetylated sugar and 1,3-dibromo-2-propanol in 60-73% yields. D-Glucose, D-mannose, D-galactose, D-xylose, D-ribose, and maltose are utilized as sugar molecules in this work. The diamine moiety was connected to the C1 carbon of the glycopyranose ring via an O-glycoside bond. All of the anomeric configurations and sugar puckering conformations, except in the D-maltose derivative, were determined by X-ray crystallography of the diazido or dibromo precursors. While glycosidation of peracetylated galactopyranose with 1,3-dibromo-2-propanol in the presence of boron trifluoride afforded both anomers, the neighboring group participation of the 2-acetoxy group yielded a single anomer for the other substrates. This method has been used to synthesize a library of sugar-pendant diamines including an OH-protected derivative (6), and an N,N'-diisopropyl-substituted derivative (7). A similar series of reactions using 2,3-dibromo-1-propanol gave ethylenediamine-type derivatives (11), and bis(bromomethyl)bis(hydroxymethyl)methane (12) gave bisglucose-pendant derivatives (16).

Carbohydrate Sequence↗
PubMed2001

A new fluorescent assay for sialyltransferase.

A new fluorescent assay for the sialyltransferase reaction was established. After incubation of the sialyltransferase reaction, the sialyloligosaccharide obtained was treated by acid hydrolysis, and then the NeuAc that was released was labeled with 1,2-diamino-4,5-methylenedioxibenzene. The fluorescent-labeled NeuAc could be estimated by HPLC (excitation: 373 nm; emission: 448 nm) and a Lineweaver-Burk plot could be plotted with the data from this analysis.

Chromatography, High Pressure Liquid↗
PubMed2001

A new antibiotic CJ-17,665 from Aspergillus ochraceus.

A new antibiotic, CJ-17,665 (I) was isolated from the fermentation broth of Aspergillus ochraceus, CL41582. It inhibits growth of multi-drug resistant Staphylococcus aureus, Streptococcus pyogenes, and Enterococcus faecalis, with MICs of 12.5, 12.5 and 25 microg/ml, respectively. The structure contains a diketopiperazine and an indole N-oxide moiety that is unusual in natural products.

Anti-Bacterial Agents↗
PubMed2001

[Three cases of pituitary abscess].

We report three cases of pituitary abscess. Three patients, all females, had suffered headache and complained of general fatigue. In each case magnetic resonance imaging (MRI) revealed a sellar mass with suprasellar extension. T1-weighted images revealed an isointense or slightly hypointense lesion with thin ring-enhancement following gadolinium injection. No inflammatory signs were found in two cases. In one case, a gradual change in clinical symptoms and MRI findings was noted: the hypophyseal hemorrhagic lesion detected on MRI changed into a cystic lesion with thin ring-enhancement. Transsphenoidal surgery was performed in all three cases. In each case, however, no organism was cultured and no tumor component was found. It is difficult to diagnose pituitary abscess prior to surgery if no inflammatory signs are present. Diagnosis of this condition requires careful radiological evaluation. Findings of a suprasellar round cystic mass with thin ring-enhancement on MRI associated with thickened stalk, hyperprolactinemia, and diabetes insipidus may be suggestive of a pituitary abscess.

Adult↗
PubMed2001

[Retropubic radical prostatectomy with the use of ultrasonic cutting and coagulating system (AutoSonix System)].

We report our experience of using the ultrasonic coagulating and cutting device, AutoSonix System, which began in January 2000 to reduce the amount of bleeding in radical retropubic prostatectomy. The mean age of the 24 prostate cancer patients operated on was 68.2 years old. The operation results were excellent; the mean operation time was 227 +/- 29 minutes (mean +/- standard deviation), and the mean amount of blood loss during the operation was 215 +/- 114 ml. There were no major complications. After three months or more of follow-up, no patients needed any pads for urinary incontinence. Only one case showed a stricture at cystourethral anastomosis. AutoSonix System was useful to reduce the blood loss from the venous plexus in the pelvic cavity. We believe that radical prostatectomy would be safer if this device would be used by the urologist.

Aged↗
PubMed2000

Decrease in the regeneration potential of long-term cell suspension cultures of Lilium formosanum Wallace and its restoration by the auxin transport inhibitor, 2,3,5-triiodobenzoic acid.

Cell suspension cultures of Lilium formosanum Wallace were initiated from bulb scale-derived calli and subcultured every 2 weeks using a medium containing 5 µM 4-amino-3,5,6-trichloropicolinic acid (picloram). Almost all cell clumps from the suspension cultures developed numerous somatic embryos following their transfer onto a plant growth regulator-free medium, while they vigorously produced shoot buds on media containing 0.5 or 5 µM 6-benzyladenine (BA). The high regeneration potential on a plant growth regulator-free medium was maintained for up to 54 months, but it gradually decreased thereafter, and only a few adventitious shoots and embryos were obtained from 75-month-old cultures. For restoring the regeneration potential of these cultures, various treatments with plant growth regulators were applied, among which about 10-fold increases in the number of regenerated shoot buds were obtained with 0.5 or 5 µM 2,3,5-triiodobenzoic acid (TIBA) in combination with 0.5 or 5 µM BA or N-(1,2,3-thiadiazol-5-yl)-N'-phenylurea (thidiazuron). Only shoot buds were produced from the cell clumps cultured on TIBA-containing media, and these shoot buds developed into complete plantlets after they were excised from the calli and transferred to a plant growth regulator-free medium.

Journal Article↗
PubMed2000

The safety and usefulness of cool head-warm body perfusion in aortic surgery.

OBJECTIVE: To determine the safety and usefulness of antegrade hypothermic cerebral perfusion in conjunction with mild hypothermic (tepid) visceral perfusion (so-called cool head-warm body perfusion; CHWB) in aortic surgery; the clinical outcomes and perioperative data on this new technique were retrospectively analyzed. METHODS: From January 1990 to March 1999, 59 patients underwent ascending aorta or aortic arch surgery using antegrade selective cerebral perfusion (SCP). Three perfusion techniques, differentiated by perfusion temperature, were used, those being deep hypothermia (DH; nasopharyngeal temperature of 20 degrees C, n=14), moderate hypothermia (MH; nasopharyngeal temperature of 28 degrees C, n=17) and CHWB (nasopharyngeal temperature of 25 degrees C and bladder temperature of 32 degrees C, n=28). Selection of the technique largely followed a chronological pattern, in this order: DH, MH and, more recently, CHWB. The three groups were retrospectively compared in terms of operative outcome, duration of cardiopulmonary bypass (CPB) and operation, and intraoperative blood loss. RESULTS: The early (within 30 days after surgery) mortality/hospital mortality (including operative mortality) was 7.1/21.4, 5.9/11.8 and 3.6/7.1% in the DH, MH and CHWB groups, respectively. The rate of stroke was 7.1, 6.3 and 3.6% in the DH, MH and CHWB groups, respectively. No statistical difference was found in early or hospital mortality, or in the rate of stroke among the three groups. The CPB time, especially the time for rewarming, was significantly shorter in the CHWB than in the DH group. Likewise, the operation time, especially the time after CPB, was significantly shorter in the CHWB than in the DH and MH groups. Blood loss was significantly less in the CHWB than in the DH group. CONCLUSION: Our data suggest that CHWB perfusion in aortic surgery is a safe and useful technique in shortening the operation time and reducing blood loss, but further prospective study is necessary.

Aged↗