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T Sasaki

Publications and source records attributed to T Sasaki.

At least 91 records · Page 5Linked to original sources
PubMed2003

Electronic band structure and Fermi surface of CaB6 studied by angle-resolved photoemission spectroscopy.

We report high-resolution angle-resolved photoemission spectroscopy (ARPES) on CaB6. The band structure determined by ARPES shows a 1 eV energy gap at the X point between the valence and the conduction bands. We found a small electron pocket at the X point, whose carrier number is estimated to be (4-5) x 10(19) cm(-3), in good agreement with the Hall resistivity measurement with the same crystal. The experimental results are discussed in comparison with band structure calculations and theoretical models for the high-temperature ferromagnetism.

Journal Article↗
PubMed2003

Proposal of fibrosis index using image analyzer as a quantitative histological evaluation of liver fibrosis in biliary atresia.

This study was designed to elucidate whether the fibrosis index (FI), which was measured as a ratio of histological fibrotic tissue area to the whole area using an image analyzer, could reflect liver function and long-term prognosis in biliary atresia (BA). Liver biopsies were performed in 46 BA patients at hepatic portoenterostomy (HPE) and stoma closure. The chronological difference rate of FI (FIDR) was the monthly FI difference between HPE and stoma closure. FI at HPE and stoma closure was significantly higher than in the control. FI at HPE and at stoma closure significantly correlated with gammaGTP or T.Bil, D.Bil, cholinesterase and total bile acid, respectively. FIDR in jaundice-free group was significantly lower than in jaundiced group at 5 years after HPE. FIDR in V-2 (varices with red-color sign) was significantly higher than in V-0 (no varices) or V-1 (varices without red-color sign). ICG-K value significantly correlated with FIDR. FI at stoma closure or FIDR was significantly lower in living patients than in patients who eventually died or underwent liver transplantation. In conclusion, FI can reflect the degree of cholestasis in BA. FIDR would be useful for predicting long-term outcome in BA.

Analysis of Variance↗
PubMed2003

Activation of caspase-12 by endoplasmic reticulum stress induced by transient middle cerebral artery occlusion in mice.

We sought to clarify the involvement of caspase-12, a representative molecule related to endoplasmic reticulum (ER) stress-induced cell-death signaling pathways, in neuronal death resulting from ischemia/reperfusion in mice. Transient focal cerebral ischemia (1 h) was produced by intraluminal occlusion of the middle cerebral artery (MCA). We assessed the expression patterns of caspase-12, Bip/GRP78, an ER-resident molecular chaperone whose expression serves as a good marker of ER stress, and caspase-7 by Western blotting and/or immunohistochemistry. Double-fluorescent staining of caspase-12 immunohistochemistry and the terminal deoxynucleotidyl transferase-mediated DNA nick-end labeling (TUNEL) method was performed to clarify the involvement of caspase-12 in cell death. We confirmed that ER stress was induced during reperfusion in our model, as witnessed by up-regulated Bip/GRP78 expression in the MCA territory. Western blot analysis revealed that caspase-12 activation occurred at 5-23 h of reperfusion, and immunoreactivity for caspase-12 was enhanced mainly in striatal neurons on the ischemic side at the same time points. We found the co-localization of caspase-12 immunoreactivity and DNA fragmentation detectable by the TUNEL method. We did not detect the presence of caspase-7 in the ER fraction at the period of caspase-12 cleavage. Our results imply that cerebral ischemia/reperfusion induces ER stress and that caspase-12 activation concurred with ER stress. Caspase-12 seems to be involved in neuronal death induced by ischemia/reperfusion. Caspase-7 is not likely to contribute to the cleavage of caspase-12 in our experimental model.

Animals↗
PubMed2003

Involvement of vacuolar H+ -ATPase in incorporation of risedronate into osteoclasts.

Although osteoclasts incorporate bisphosphonates during bone resorption, the mechanism of this incorporation by osteoclasts is not known. We previously reported that bisphosphonates disrupt the actin rings (clear zones) formed in normal osteoclasts, but did not disrupt actin rings in osteoclasts derived from osteosclerotic oc/oc mice, which have a defect in the gene encoding vacuolar H(+)-ATPase (V-ATPase). The present study showed that V-ATPase is directly involved in the incorporation of risedronate, a nitrogen containing bisphosphonate, into osteoclasts. Treatment of osteoclasts with risedronate disrupted actin rings and inhibited pit formation by osteoclasts on dentine slices. Bafilomycin A(1), a V-ATPase inhibitor, inhibited the pit-forming activity of osteoclasts but did not disrupt actin rings. Risedronate failed to disrupt actin rings in the presence of bafilomycin A(1). E-64, a lysosomal cysteine proteinase inhibitor, showed no inhibitory effect on the demineralization of dentine by osteoclasts but inhibited the digestion of dentine matrix proteins without disrupting actin rings. Risedronate disrupted actin rings even in the presence of E-64. Treatment of osteoclasts placed on plastic plates with risedronate also disrupted actin rings. Bafilomycin A(1) but not E64 prevented the disruption of actin rings in osteoclasts treated with risedronate on plastic plates. Inhibition of V-ATPase with bafilomycin A(1) also prevented disruption of actin rings by etidronate, a non-nitrogen-containing bisphosphonate. These results suggest that V-ATPase induced acidification beneath the ruffled borders of osteoclasts and subsequent bone demineralization triggers the incorporation of both nitrogen-containing and non-nitrogen-containing bisphosphonates into osteoclasts.

Actins↗
PubMed2003

Destruxins, cyclodepsipeptides, block the formation of actin rings and prominent clear zones and ruffled borders in osteoclasts.

Bone-resorbing osteoclasts exhibit polarized morphological structures such as actin rings, clear zones, and ruffled borders. To gain insight into the mechanism of bone-resorbing activity of osteoclast and to discover new types of anti-resorptive agents, we have screened for natural compounds that inhibit the bone-resorbing activity of osteoclast-like multinucleated cells (OCLs). Destruxin B (DestB) and E (DestE), cyclodepsipeptides, were found to inhibit pit formation without affecting osteoclast differentiation and survival. Destruxins reversibly induced morphological changes in OCLs in a dose-dependent manner (DestB, 0.2-1 microM; DestE, 0.01-0.05 microM) and inhibited pit formation. Destruxin-induced morphological changes were accompanied by disruption of the actin rings in OCLs. The formation of actin rings in OCLs after adhesion was also inhibited by destruxins. Electron microscopical analysis revealed that destruxin-treated OCLs on dentine slices have no prominent clear zones and ruffled borders. The effective concentrations of destruxins on the morphological changes were almost the same as those that inhibited bone resorption in organ culture system. These results suggest that the anti-resorptive effects of destruxins result from induction of a disorder of the morphological structures in polarized OCLs.

Acid Phosphatase↗
PubMed2003

Regression of an unresectable pancreatic tumor following nonmyeloablative allogeneic peripheral-blood stem-cell transplantation.

A 59-year-old female with an unresectable, large pancreatic tumor (10.0 x 8.0 cm(2) on CT scan) underwent nonmyeloablative allogeneic peripheral-blood stem-cell transplantation from her HLA-identical sibling. Pronounced tumor regression and relief from pain without acute graft-versus-host disease (GVHD) were observed following transplantation. The patient is surviving (more than 300 days) after transplantation, with extensive chronic GVHD, and has tumor regression with an 80% reduction in tumor size. The observed clinical course may suggest a graft-versus-tumor effect on the pancreatic tumor following allogeneic stem-cell transplantation.

Adenocarcinoma↗
PubMed2003

Osteogenic potential of five different recombinant human bone morphogenetic protein adenoviral vectors in the rat.

Bone morphogenetic protein (BMP) adenoviral vectors for the induction of osteogenesis are being developed for the treatment of bone pathology. However, it is still unknown which BMP adenoviral vector has the highest potential to stimulate bone formation in vivo. In this study, the osteogenic activities of recombinant human BMP-2, BMP-4, BMP-6, BMP-7, and BMP-9 adenoviruses were compared in vitro, in athymic nude rats, and in Sprague-Dawley rats. In vitro osteogenic activity was assessed by measuring the alkaline phosphatase activity in C2C12 cells transduced by the various BMP vectors. The alkaline phosphatase activity induced by 2 x 10(5) PFU/well of BMP viral vector was 4890 x 10(-12) U/well for ADCMVBMP-9, 302 x 10(-12) U/well for ADCMVBMP-4, 220 x 10(-12) U/well for ADCMVBMP-6, 45 x 10(-12) U/well for ADCMVBMP-2, and 0.43 x 10(-12) U/well for ADCMVBMP-7. The average volume of new bone induced by 10(7) PFU of BMP vector in athymic nude rats was 0.37+/-0.03 cm(3) for ADCMVBMP-2, 0.89+/-0.07 cm(3) for ADCMVBMP-4, 1.02+/-0.07 cm(3) for ADCMVBMP-6, 0.24+/-0.05 cm(3) for ADCMVBMP-7, and 0.63+/-0.07 cm(3) for ADCMVBMP-9. In immunocompetent Sprague-Dawley rats, no bone formation was demonstrated in the ADCMVBMP-2, ADCMVBMP-4, and ADCMVBMP-7 groups. ADCMVBMP-6 at a viral dose of 10(8) PFU induced 0.10+/-0.03 cm(3) of new bone, whereas ADCMVBMP-9 at a lower viral dose of 10(7) PFU induced more bone, with an average volume of 0.29+/-0.01 cm(3).

Adenoviridae↗
PubMed2003

Effects of combination therapy with a luteinizing hormone-releasing hormone agonist and chlormadinone acetate on rat prostate weight and plasma testosterone levels.

We investigated whether the combination of chlormadinone acetate (CMA) and a luteinizing hormone releasing hormone (LH-RH) agonist, leuprorelin acetate (leuprorelin), more markedly decreased ventral prostate and seminal vesicle weights and plasma sex hormone levels in male rats. Four weeks after administration of 0.28, 0.84 or 2.8 mg/kg of leuprorelin, ventral prostate weights significantly decreased (53.8, 54.4 and 64.1%) and the plasma testosterone levels significantly lowered, but not dose-dependently. After repetitive administrations of 3 and 30 mg/kg/day of CMA, the rates of ventral prostatic atrophy were 37.1 and 65.9%, respectively. Although there was no change in the plasma testosterone level at 3 mg/kg, 30 mg/kg of CMA significantly decreased the level. A combination of leuprorelin (0.28 mg/kg) and CMA (3 or 30 mg/kg) more potently induced ventral prostatic and seminal vesicle atrophy than leuprorelin alone. Furthermore, a combination of leuprorelin and CMA (30 mg/kg) more markedly decreased the plasma testosterone level. According to the pharmacokinetic data for CMA in male rats, the doses of CMA correspond to the clinical dose. These findings suggest that combination therapy with an LH-RH agonist and CMA is more useful than therapy with the agonist alone in the treatment of prostate cancer.

Androgen Antagonists↗
PubMed2003

Effects of staphylococci on cytokine production from human keratinocytes.

BACKGROUND: Staphylococcus skin infection is characterized by the infiltration of numerous neutrophils within the epidermis; however, the precise mechanism of epidermal infiltration of neutrophils during skin infection with staphylococci is not well understood and the factors regulating the neutrophil recruitment are yet to be determined. OBJECTIVES: We investigated the effects of staphylococci on cytokine production from keratinocytes, specifically to elucidate the mechanisms of neutrophil infiltration within the epidermis in cutaneous microbial infection. METHODS: Cytokine production from human keratinocytes was examined after stimulation with heat-killed Staphylococcus aureus, S. epidermidis and S. intermedius. RESULTS: Interleukin (IL)-6 and IL-8 were detected in the culture supernatants by enzyme-linked immunosorbent assay but IL-1beta, monocyte chemotactic protein-1 and tumour necrosis factor-alpha were not. IL-6 and IL-8 mRNAs were also confirmed by reverse transcription-polymerase chain reaction in the keratinocytes stimulated with killed staphylococci for 1, 3, 6, 10 and 24 h. CONCLUSIONS: These results could explain the epidermal infiltration of neutrophils in cutaneous infection with staphylococci, suggesting that the analysis of cytokines might add valuable information for the pathogenesis of cutaneous infection with Staphylococcus species.

Cells, Cultured↗
PubMed2003

Labral-ligamentous complex of the shoulder. Evaluation with double oblique axial MR arthrography.

PURPOSE: To assess the ability of double oblique axial (DOA) MR arthrography in evaluating labral-ligamentous complex compared with conventional axial (CA) MR arthrography. MATERIAL AND METHODS: MR arthrography of 51 shoulders, subsequently examined with arthroscopy, were retrospectively reviewed. DOA imaging was performed in all 51 shoulders and both DOA and CA imaging in 37 using a 1.5 T unit with gradient recalled-echo T2*-weighted sequences. DOA imaging was performed using perpendicular planes to the long axis of the glenoid fossa obtained by an oblique sagittal scout image. We compared the ability of DOA with that of CA MR arthrography to assess labral injuries and to demonstrate the whole length of the anterior band of the inferior glenohumeral ligament (AIGHL), which were shown to be intact by arthroscopy. RESULTS: For anterior labral injuries, sensitivity and specificity were 87% and 93% with CA, and 94% and 100% with DOA imaging, respectively. For posterior labral injuries, sensitivity and specificity were 47% and 100% with CA, and 79% and 96% with DOA imaging, respectively. There were no statistically significant differences between CA and DOA images, except for the ability to diagnose posterior labral injuries, where DOA imaging had a significant superior sensitivity (p=0.0327). DOA images also demonstrated the whole length of the intact AIGHL in 10 of 11 shoulders, while CA imaging showed this in only 3 of 11. CONCLUSION: DOA imaging was equal or better than CA imaging for evaluating the labral-ligamentous complex.

Adult↗
PubMed2003

A method for evaluating the entrance surface dose from the measurement of exposure and half value layer in intraoral radiography using a radiophotoluminescent dosemeter.

A method for measuring entrance surface dose in intraoral radiography for nationwide survey for the determination of guidance levels was developed using a commercially available radiophotoluminescent dosemeter (RPLD) system. From the ratio of the readings of the RPLD detectors. with and without a 1 mm thick aluminium filter, half value layer (HVL) and the energy dependency correction factor were derived. HVL and exposure for intraoral radiography were obtained with uncertainties of +/- 0.11 mmAl (SD) and +/- 2.1% (CV), respectively. This has been achieved by calibration at various beam qualities used in intraoral radiography. The HVLs and outputs of intraoral radiography units were measured by means of the mailed RPLD holders and also by ionisation chambers in 19 dental schools in Japan. Results obtained from the two methods of measurement agreed well for both HVLs and outputs.

Air↗
PubMed2003

Hemispheric dominance of tongue control depends on the chewing-side preference.

Blood-oxygenation-level-dependent (BOLD)-functional magnetic resonance imaging (fMRI) is known to be a non-invasive technique for studying human brain function. The purpose of this study was to apply BOLD-fMRI to identify brain areas responsible for producing tongue movements and their relation to chewing-side preference in 15 normal right-handed volunteers. A marked increase in BOLD signals was detected in primary sensorimotor cortices upon protrusion and in rightward and leftward tongue movements compared with at rest. In 10 subjects with an evident chewing-side preference, the BOLD signal change in the primary sensorimotor cortex was significantly greater on the side contralateral to the preferred chewing side. The results suggest that there is a relationship between hemispheric dominance and chewing-side preference in primary sensorimotor cortices responsible for tongue movements.

Adult↗
PubMed2003

Artifacts from dental casting alloys in magnetic resonance imaging.

The potential advantage of magnetic resonance imaging (MRI) has been limited by artifacts due to the presence of metallic materials. For quantitative evaluation of the magnitude of artifacts from dental casting alloys and implant materials in MR imaging, 11 dental casting or implant materials were imaged by means of 1.5 T MRI apparatus with three different sequences. Mean and standard deviation of water signal intensity (SI) around the sample in the region of interest (1200 mm(2)) were determined, and the coefficient of variation was compared for evaluation of the homogeneity of the SI. A variety of artifacts with different magnitudes was observed. Only one of the samples, composed mainly of Pd, In, and Sb, showed no artifacts in all imaging sequences. We concluded that selection of specific dental casting alloys according to their elemental compositions could minimize the metal artifacts in MRI; however, titanium alloys currently pose a problem with respect to causing MRI artifacts.

Alloys↗
PubMed2003

Maxillary bone invasion by gingival carcinoma as an indicator of cervical metastasis.

OBJECTIVES: To evaluate the significance of maxillary bone invasion by gingival carcinoma as an indicator of cervical metastasis. METHODS: Twenty-one patients with squamous cell carcinoma of the upper gingiva were included in the study. The extent of bone invasion was assessed by dental CT. Six patients had cervical metastases at the initial examination and eight more developed them during the 2-year follow-up period. The relationship of cervical metastases with age and gender of these patients, as well as with the size of the lesion and extent of bone invasion, was examined by logistic multivariate regression analysis. RESULTS: There was a significant relationship between the presence of bone invasion and the presence of cervical metastasis (P<0.05). CONCLUSIONS: Maxillary bone invasion is an indicator of cervical metastasis in gingival carcinoma.

Adult↗
PubMed2003

Accuracy of panoramic radiography in assessing the dimensions of radiolucent jaw lesions with distinct or indistinct borders.

OBJECTIVES: To evaluate the accuracy of panoramic radiography (PR) in assessing the dimensions of mandibular lesions. METHODS: One hundred and fifteen cases exhibiting radiolucent lesions in the mandibular premolar, molar or ramus area were selected retrospectively. They were divided into four types: cyst with sclerotic margin (Type I); cyst without sclerotic margin (Type II); ameloblastoma (Type III); or squamous cell carcinoma (Type IV). Maximum mesiodistal length and superoinferior height were measured on PR (Lpmax and Hpmax, respectively) and on CT (Lcmax and Hcmax, respectively) and the results were compared. RESULTS: Correlation coefficients between Lpmax and Lcmax and between Hpmax and Hcmax were high for Type I, II and III lesions but were significantly lower for Type IV lesions. Regression coefficients between Lpmax and Lcmax and between Hpmax and Hcmax were indistinguishable from 1.0 for all types of lesions. The mean relative difference between Lpmax and Lcmax varied from 1.2% to 8.2%. The difference was only -0.3% for larger lesions of combined Types I and II. The mean relative difference between Hpmax and Hcmax varied from--3.5% to 1.1% depending on the type of lesions. CONCLUSION: PR is accurate for assessing the dimensions of radiolucent lesions in the posterior mandible when the margins are well defined.

Adolescent↗