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Y Sakai

Publications and source records attributed to Y Sakai.

At least 37 records · Page 2Linked to original sources
PubMed2004

Observation of B(+)-->pppi+, B0-->ppK0, and B(+)-->ppK(*+).

We report the first observation of a b-->u type charmless baryonic B decay, B+-->pppi(+), as well as b-->s type B0-->ppK0 and B+-->ppK(*+) decays. The analysis is based on a 78 fb(-1) data sample recorded on the Upsilon(4S) resonance with the Belle detector at KEKB. We find B(B+-->pppi(+))=(3.06(+0.73)(-0.62)+/-0.37)x10(-6), B(B0-->ppK0)=(1.88(+0.77)(-0.60)+/-0.23)x10(-6), and B(B+-->ppK(*+))=(10.3(+3.6+1.3)(-2.8-1.7))x10(-6). We also update B(B+-->ppK+)=(5.66(+0.67)(-0.57)+/-0.62)x10(-6) and present an upper limit on B(B0-->ppK(*0)) at the 90% confidence level. A common feature of the observed decay modes is threshold peaking in baryon pair invariant mass.

Journal Article↗
PubMed2004

Observation of the radiative decay D0-->phigamma.

We report the observation of the decay D0-->phigamma with a statistical significance of 5.4sigma in 78.1 fb(-1) of data collected by the Belle experiment at the KEKB e+e- collider. This is the first observation of a flavor-changing radiative decay of a charmed meson. The Cabibbo- and color-suppressed decays D0-->phipi(0), phieta are also observed for the first time. We measure branching fractions B(D0-->phigamma)=[2.60(+0.70)(-0.61)(stat)+0.15-0.17(syst)] x 10(-5), B(D0-->phipi(0))=[8.01+/-0.26(stat)+/-0.47(syst)] x 10(-4), and B(D0-->phieta)=[1.48+/-0.47(stat)+/-0.09(syst)] x 10(-4).

Journal Article↗
PubMed2004

Functional MxA promoter polymorphism associated with subacute sclerosing panencephalitis.

BACKGROUND: The antivirally active MxA protein is induced by interferon (IFN) alpha/beta and inhibits the replication of single-stranded RNA viruses including measles virus (MV). The authors investigated whether the MxA gene contributed to the development of subacute sclerosing panencephalitis (SSPE) in Japanese individuals. METHODS: Single-nucleotide polymorphisms (SNP) in the promoter region of the MxA gene were screened, association studies were performed between two SNP and SSPE, and then a functional difference in the promoter activities of the two SNP was investigated by a dual luciferase reporter assay. RESULTS: Four SNP were found (-88 G/T, -123 C/A, -200 T/C, and -213 G/T), and SSPE patients exhibited a higher frequency of both the -88T allele and the -88TT genotype than controls (p = 0.040 and 0.003). The IFN-induced up-regulation of the MxA promoter activity of the sequence with -88T was found to be significantly higher than that with G. CONCLUSIONS: MxA promoter -88 G/T SNP may confer host genetic susceptibility to SSPE in Japanese individuals. The finding that homozygotes of the MxA -88T allele with a high MxA-producing capability were more frequently seen in SSPE patients suggests that the MxA protein promotes the establishment of persistent MV infection of neural cells.

Adolescent↗
PubMed2004

Fabrication of microstructures in photosensitive biodegradable polymers for tissue engineering applications.

Combining the MEMS technology and biology requirements for tissue engineering, the fabrication processes of microstructured chambers and microchannels made in biodegradable photosensitive polymers are presented. The fabrication processes, based on softlithography are very fast and flexible. Various single and multistepwise microstructures could be achieved using the biodegradable polymers. Microstructures down to 50microm, which are suitable for liver reconstructs, could be fabricated. As the pCLLA acrylate photosensitive polymer has interesting property for implantable bioreactors, that is, its softness, we examined the ability of various mammalian cells to grow and spread on it. With Hep G2 cells, human umbilical blood vessel endothelial cells (HUVEC), 3T3-L1 mouse fibroblasts, static cultures could be successfully performed on single stepwise microstructures. Then, by using this photosensitive biodegradable polymer, a microstructure with simple fluidic channels is fabricated and a perfusion experiment could be carried out. Both cell cultures and perfusion experiments suggested the possibility to use the present photosensitive polymer as microfluidic supports for biodegradable bioreactors for implantation applications.

3T3-L1 Cells↗
PubMed2004

Acceleration of superoxide generation in polymorphonuclear leukocytes and inhibition of platelet aggregation by alk(en)yl thiosulfates derived from onion and garlic in dogs and humans.

We recently identified sodium n-propyl thiosulfate (NPTS) and sodium 2-propenyl thiosulfate (2PTS) from boiled onion and garlic, respectively, as causative agents of hemolytic anemia in dogs. We present here data concerning the effects of these alk(en)yl thiosulfates on superoxide (O(2)(-)) generation in peripheral polymorphonuclear leukocytes (PMNs) and on adenosine 5'-diphosphate (ADP)-induced platelet aggregation in dogs and humans in vitro. Both NPTS and 2PTS increased O(2)(-) generation significantly (P<0.05 at 1mM NPTS, P<0.005 at 0.1 and 1mM 2PTS) and reduced its reaction time significantly (P<0.05 between 0.01 and 1mM NPTS and at 1mM 2PTS) in canine PMNs stimulated by phorbol 12-myristate 13-acetate, compared with the control without alk(en)yl thiosulfates. However, a tendency to return to the control level was observed at 10mM of the alk(en)yl thiosulfates in both O(2)(-) generation and its reaction time. Although NPTS and 2PTS did not exert any significant effect on the O(2)(-) generation in human PMNs, 2PTS reduced its reaction time significantly (P<0.05) at 1 and 10mM compared with the control, showing that 2PTS accelerated O(2)(-) generation in human PMNs. The difference in effects on O(2)(-) generation may be due to that in susceptibility to alk(en)yl thiosulfates between canine and human PMNs. On the other hand, NPTS and 2PTS were shown to significantly inhibit ADP-induced platelet aggregation at 0.01mM (P<0.01) in canine platelets and at 0.001-0.1mM (P<0.05) in human platelets. In contrast, the maximal aggregation percentage returned to the control level at 1mM of alk(en)yl thiosulfates in both canine and human platelets. From these results, we conclude that NPTS and 2PTS have the potential to promote immune functions and prevent cardiovascular diseases.

Adenosine Diphosphate↗
PubMed2004

Excess accumulation of body fat is related to dyslipidemia in normal-weight subjects.

OBJECTIVE: To assess the relationship of fat mass (FM) and its distribution to hypertension and dyslipidemia in normal-weight Japanese individuals. DESIGN: Cross-sectional study. SUBJECTS: Apparently healthy Japanese subjects with a body mass index (BMI) between 20 and 23.5 kg/m(2) (265 males and 741 females, age 21-69 y). MEASUREMENTS: BMI, waist circumference (WC), waist-hip ratio (WHR), systolic and diastolic blood pressure, serum levels of total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-C) and triglyceride (TG) were measured. Low-density lipoprotein-cholesterol (LDL-C) was calculated by the Friedewald formula. Percentage fat mass (%FM) and trunk fat mass-leg fat mass ratio (FM(trunk)/FM(legs)) were obtained by dual-energy X-ray absorptiometry. RESULTS: WC, WHR, %FM and FM(trunk)/FM(legs) were significantly correlated with TC, LDL-C, HDL-C and TG with the tendency of FM(trunk)/FM(legs) to show the strongest correlations. For %FM and FM(trunk)/FM(legs) in both sexes, odds ratios (ORs) of the third tertiles with respect to the first tertiles increased for LDL-C elevation, TG elevation and dyslipidemia. In males, ORs of the third tertiles of WC were significantly high for LDL-C elevation and dyslipidemia whereas those of WHR were high for TG elevation and dyslipidemia. ORs of the third tertiles of WC and WHR were significantly high for TG elevation in females. BMI was not associated with the risk of abnormal lipid levels. ORs for hypertension showed significant increases in none of the variables of obesity. CONCLUSIONS: Excess accumulation of FM, especially to the upper body, was related to dyslipidemia in normal-weight subjects. Simple anthropometric variables, WC and WHR, may be useful for screening and management of dyslipidemia in these subjects.

Absorptiometry, Photon↗
PubMed2004

Comparison of duodenal stent placement with surgical gastrojejunostomy for palliation in patients with duodenal obstructions caused by pancreaticobiliary malignancies.

BACKGROUND AND STUDY AIMS: Palliative treatment for duodenal stenosis with an enteral stent is effective in enhancing the quality of life of patients with duodenal obstruction. There have been no thorough comparisons of duodenal stent placement with standard surgical gastrojejunostomy. The present study evaluated the outcome of duodenal stent placement and surgical gastrojejunostomy for palliation of duodenal stenosis caused by pancreaticobiliary malignancies. PATIENTS AND METHODS: Medical records for patients who underwent palliative enteral stenting during the past 9 years were retrospectively reviewed, and the patients' clinical outcome was compared with that in patients who underwent open surgical gastrojejunostomy during the same period. Patients who underwent prophylactic gastrojejunostomy were excluded from the study. RESULTS: Twenty patients (11 men, nine women; mean age 71.8 years) with pancreaticobiliary malignancy underwent palliative enteral stenting (stent group). Nineteen patients (12 men, seven women; mean age 68.7 years) with pancreaticobiliary malignancies underwent surgical gastrojejunostomy (bypass group). In the stent group, the diagnoses were 12 pancreatic cancers, six gallbladder cancers, one bile duct cancer, and one ampullary cancer. In the bypass group, the diagnoses were 14 pancreatic cancers and five gallbladder cancers. There were no significant differences between the two groups with regard to clinical background. Both procedures were successful. There were no differences between the two groups with regard to the technical or clinical success rates, patient survival, possibility of discharge, need for parenteral nutrition, or incidence of complications. However, the time from the procedure to resumption of food intake was shorter in the stent group than in the bypass group (1 day vs. 9 days; P < 0.0001). Improvement in the performance score after the procedure was observed more frequently in the stent group (65 % vs. 26.3 %; P < 0.05). In terms of the median hospital stay from the time of the procedure to the time of initial discharge home (12 patients vs. nine patients), there was no statistical difference (15 days vs. 30 days) due to the small size of the sample. There was no procedure-related mortality in either group. CONCLUSIONS: Palliative stent placement was more beneficial than surgical gastrojejunostomy in enhancing the quality of life of patients with duodenal obstruction due to pancreaticobiliary malignancies.

Aged↗
PubMed2004

Effects of kava (Kava-kava, 'Awa, Yaqona, Piper methysticum) on c-DNA-expressed cytochrome P450 enzymes and human cryopreserved hepatocytes.

The effects of the herbal product kava (Kava kava, 'Awa, Yaqona, Piper methysticum) on human P450 isoforms were studied in vitro using both cDNA-expressed human enzymes and cryopreserved human hepatocytes. Increasing concentrations of an ethanolic extract of dried kava root and three purified kava lactones (methysticin, desmethoxyyangonin, and yangonin) were tested for their ability to inhibit the catalytic activity of a panel of P450 isoforms (1A2, 2A6, 2C9, C2C19, 2D6, 2E1, and 3A4) present as c-DNA expressed-enzymes and in previously cryopreserved human hepatocytes. In addition, the test compounds' effect on hepatocyte viability was evaluated by measuring cellular ATP content. In both models, the kava extract and the three kava lactones were found to be potent inhibitors of CYPs 1A2, 2C9, 2C19, 2E1, and 3A4 with IC50 values of approximately 10 microM. The test compounds were also moderately cytotoxic to human hepatocytes (EC50 values of approximately 50 microM). Methysticin was the most potent enzyme inhibitor as well as the most cytotoxic, followed by (in order of potency:) the kava root extract, desmethoxyyangonin, and yangonin. Our results suggest that the drug interaction and hepatotoxic potential of kava should be further investigated.

Cryopreservation↗
PubMed2004

Efficacy of immunoadsorbent devices for maintaining hepatic function in ex vivo direct xenogenic hemoperfusion.

We have developed a new system for direct xenogenic hemoperfusion of a bioartificial liver support system adopting two types of immunoadsorbent devices. In this study, we compared the efficacy of each immunoadsorbent device in maintaining porcine hepatocyte function during 3 h perfusion treatment in a canine liver failure model. Suppression of humoral immunity by the immunoglobulin adsorber prevented immunogenic hepatocyte injury more effectively, and the system showed higher hepatic function when compared with suppression of cell-mediated immunity by the leukocyte adsorber. However, single use of immunoglobulin adsorber was less effective in reducing patients' systemic ammmonia levels and modulating the Fischer's ratio compared with the case of combined use of both immunoadsorbent devices. These results suggest that suppression of humoral immunity was of primary importance in preventing immunogenic hepatocyte injury, however the adsorption of leukocytes may have a synergic effect on maintaining hepatocyte function in direct xenogenic hemoperfusion.

Alanine Transaminase↗
PubMed2003

Cis-acting elements sufficient for induction of FDH1 expression by formate in the methylotrophic yeast Candida boidinii.

The FDH1 gene of Candida boidinii encodes an NAD+-dependent formate dehydrogenase, which catalyzes the last reaction in the methanol dissimilation pathway. FDH1 expression is strongly induced by methanol, as are the promoters of the genes AOD1 (alcohol oxidase) and DAS1 (dihydroxyacetone synthase). FDH1 expression can be induced by formate when cells are grown on a medium containing glucose as a carbon source, whereas expression of AOD1 and DAS1 is completely repressed in the presence of glucose. Using deletion analyses, we identified two cis-acting regulatory elements, termed UAS-FM and UAS-M, respectively, in the 5' non-coding region of the FDH1 gene. Both elements were necessary for full induction of the FDH1 promoter by methanol, while only the UAS-FM element was required for full induction by formate. Irrespective of whether induction was achieved with methanol or formate, the UAS-FM element enhanced the level of induction of the FDH1 promoter in a manner dependent on the number of copies, but independent of their orientation, and also converted the ACT1 promoter from a constitutive into an inducible element. Our results not only provide a powerful promoter for heterologous gene expression, but also yield insights into the mechanism of regulation of FDH1 expression at the molecular level.

Base Sequence↗
PubMed2003

Cerebral imaging by magnetic resonance imaging and single photon emission computed tomography in systemic lupus erythematosus with central nervous system involvement.

OBJECTIVE: To assess the significance of magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) abnormalities in patients with systemic lupus erythematosus (SLE). METHODS: Forty-four patients with SLE were retrospectively analysed. Patients were classified into three groups [1 and 2: patients with central nervous system (CNS) manifestations before and after starting high-dose steroid therapy, respectively; 3: patients without CNS manifestations. MRI was performed in all 44 patients and SPECT in 31. RESULTS: Abnormal findings in MRI were found in 19 patients. MRI abnormalities were significantly more frequent in patients with CNS manifestations than in those without [71 vs 17%, odds ratio (OR) 11.9, confidence interval (CI) 2.8-49.9, P=0.0003]. After the initiation of steroid therapy, patients with CNS manifestations also had an increased frequency of abnormal MRI. No correlation was found between SPECT findings and CNS manifestations. However, patients with CNS manifestations after starting steroids showed a markedly increased frequency of abnormal MRI and SPECT compared with those without CNS manifestations (80 vs 7%; OR 56, CI 4.4-719, P=0.0003). The positive predictive value of abnormality in both techniques in developing CNS manifestations after starting steroids was 89%. CONCLUSION: MRI findings correlated with CNS manifestations in SLE. Where there is a high suspicion of CNS involvement, the combination of MRI and SPECT may be useful in predicting CNS manifestations after starting steroid therapy.

Adolescent↗
PubMed2003

Gallium-67 scintigraphy in the diagnosis and management of chronic sarcoid myopathy.

The authors describe a patient with chronic sarcoid myopathy. Except for the presence of left posterior synechia, no other organ involvement was observed. Gallium-67 ((67)Ga) scintigraphy showed many intense nodular uptake areas in both the upper and lower extremities. Treatment with oral prednisolone 30 mg/day resulted in a marked improvement on (67)Ga scintigraphy. This case suggests that (67)Ga scintigraphy is useful for the differential diagnosis of systemic myopathies and also for monitoring the effect of glucocorticoid treatment.

Aged↗
PubMed2003

Hemichrome formation observed in human haemoglobin A under various buffer conditions.

AIM: To observe hemichrome formation in human haemoglobin A under various buffer conditions. METHOD: Hemichrome formation of human oxyhaemoglobin A (HbO2) was studied spectrophotometrically in 0.1 m buffer at various temperatures and pH values. RESULTS: Following autoxidation in ferrous HbO2, it was evident that formation of hemichrome, which tends to precipitate, occurred at various stages during the course of the autoxidation reaction namely at initial, intermediate or final stages, depending on temperature and pH of the solution. By varying temperature of the solution from 35 to 55 degrees C and pH from 4.5 to 10.5, it is shown here that HbO2 exhibits high susceptibility for hemichrome formation and its occurrence is a function of pH, temperature and progress of autoxidation of HbO2. Unlike HbO2 and its separated haemoglobin chains, monomeric bovine heart myoglobin (MbO2) did not easily form hemichrome. CONCLUSION: These findings provide a clue on the crucial role of haemoglobin molecule for senescent cell recognition or homeostasis in the blood circulation.

Animals↗
PubMed2003

Enhanced in vitro maturation of subcultivated fetal human hepatocytes in three dimensional culture using poly-L-lactic acid scaffolds in the presence of oncostatin M.

Fetal human liver cell fractions, which contain large numbers of hepatocyte progenitors, have high proliferation potential in vitro. To create an engineered liver tissue equivalent of a clinically significant size, however, repeated subcultivation and functional maturation are necessary in vitro. A commercially available human fetal liver cell fraction that was cultivated for some time in vitro has been reported to lose liver specific functions almost completely. We therefore investigated the effects of oncostatin M (OSM) and hepatocyte growth factor (HGF) in long-term three-dimensional (3D) culture using macroporous poly-L-lactic acid (PLLA) scaffolds on the restoration of such liver-specific functions of the fraction. 3D culture using PLLA scaffolds with OSM remarkably enhanced the albumin production and cytochrome P450 1A1/2 capacity with the culture time. HGF alone had no preferable effect on these functions even in 3D culture. Alpha-fetoprotein production was consistently suppressed in the 3D culture compared with that in monolayers. This suppression was not observed in the same types of culture of hepatocarcinoma Hep G2 cells. Despite these favorable observations on the 3D culture with OSM, the final attained functional levels at the 5th week were still over ten-times lower than those of Hep G2 cells when standardized with a cellular DNA amount. Although further improvement is needed for the complete functional restoration and maturation in vitro, these results demonstrate that a combination of 3D culture using PLLA scaffolds and OSM offers promising culture conditions for in vitro maturation of human hepatocyte progenitors.

Albumins↗
PubMed2002

Production of active bovine cathepsin C (dipeptidyl aminopeptidase I) in the methylotrophic yeast Candida boidinii.

The heterologous production of active bovine cathepsin C (CTC; dipeptidyl aminopeptidase I) was investigated. Attempts to express CTC in Escherichia coli were hampered by formation of inclusion bodies that were partially degraded. To overcome this impediment, secretion of recombinant CTC was attempted in the methylotrophic yeast Candida boidinii. A DNA fragment encoding bovine procathepsin C was synthesized based on preferred codon usage in C. boidinii and placed downstream of the C. boidinii proteinase A signal sequence resulting in secretion of active CTC into the culture medium. The gene was expressed under the control of the methanol-inducible formate dehydrogenase gene promoter. Production levels were significantly improved by using a protease-deficient strain, changing medium composition, and by lowering the temperature of induction. When the recombinant C. boidinii was grown for 90 h in a jar-fermenter, active CTC was secreted with a yield of up to approximately 12 mg/l.

Amino Acid Sequence↗