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Y Iwasaki

Publications and source records attributed to Y Iwasaki.

At least 19 recordsLinked to original sources
PubMed2007

Ultra-early MRI showing no abnormality in a fall victim presenting with tetraparesis.

STUDY DESIGN: Case report. SETTING: Department of Neurosurgery, Sapporo Azabu Neurosurgical Hospital and Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan. CASE REPORT: A patient presented to us with complete C4 tetraplegia after a 3-m fall. MRI performed 120 min after his fall showed spinal canal stenosis due to disk protrusion at the C3/4 level without spinal cord signal changes on T1- and T2-weighted images. He underwent laminoplasty between C2 and C6. Intraoperative ultrasound, performed 6 h after his fall, disclosed a hyperechoic lesion at the C3/4 level of the cervical cord; postoperative T2-weighted MRI, obtained at 8 h after his fall, showed high intensity at the same level. CONCLUSION: In patients with cerebral infarction, approximately 6 h between the insult and the acquisition of T2-weighted MRI are required to detect signal changes. We postulate that the time course on MRI scans obtained immediately after spinal cord injury is similar in patients with spinal cord injury and cerebral infarction and suggest that the absence of spinal cord abnormalities in the ultra-early post-injury stage is not always predictive of a good prognosis.

Accidental Falls↗
PubMed2006

Observation of B+ --> Lambda c+ Lambda c- K+ and B0 --> Lambda c+ Lambda c- K0 decays.

We report the first measurements of the doubly charmed baryonic B decays B --> Lambda c+ Lambda c- K. The B+ --> Lambda c+ Lambda c- K+ decay is observed with a branching fraction of (6.5(-0.9)(+1.0)+/-1.1+/-3.4)x10(-4) and a statistical significance of 15.4sigma. The B0 --> Lambda c+ Lambda c- K0 decay is observed with a branching fraction of (7.9(-2.3)(+2.9)+/-1.2+/-4.1)x10(-4) and a statistical significance of 6.6sigma. The branching fraction errors are statistical, systematic, and the error resulting from the uncertainty of the Lambda c+ --> pK- pi+ decay branching fraction. The analysis is based on 357 fb(-1) of data accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider.

Journal Article↗
PubMed2006

Study of J/psi-->pp[over],LambdaLambda[over] and observation of eta(c)-->LambdaLambda[over] at Belle.

We study the baryonic charmonium decays of B mesons B+-->etacK+ and B+-->J/psiK+, where the etac and J/psi subsequently decay into a pp[over] or LambdaLambda[over] pair. We measure the J/psi-->pp[over] and LambdaLambda[over] anisotropy parameters alphaB=-0.60+/-0.13+/-0.14 (pp[over]), -0.44+/-0.51+/-0.31 (LambdaLambda[over ]) and compare to results from e;{+}e;{-}-->J/psi formation experiments. We also report the first observation of etac-->LambdaLambda[over]. The measured branching fraction is B(etac-->LambdaLambda[over ])=(0.87(+0.24)/(-0.21)(stat)(+0.09/-0.14) (syst)+/-0.27(PDG))x10-3. This study is based on a 357 fb-1 data sample recorded on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider.

Journal Article↗
PubMed2006

Observation of new states decaying into Lambda(c)(+)Kappa(-)pi(+) and Lambda(c)(+)Kappa(0)/(s)pi(-).

We report the first observation of two charmed strange baryons that decay into Lambda(c)(+)Kappa(-)pi(+). The broader of the two states is measured to have a mass of 2978.5+/-2.1+/-2.0 MeV/c2 and a width of 43.5+/-7.5+/-7.0 MeV/c2. The mass and width of the narrow state are measured to be 3076.7+/-0.9+/-0.5 MeV/c;{2} and 6.2+/-1.2+/-0.8 MeV/c2, respectively. We also perform a search for the isospin partner states that decay into Lambda(c)(+)Kappa(0)/(s)pi(-) and observe a significant signal at the mass of 3082.8+/-1.8+/-1.5 MeV/c2. The data used for this analysis were accumulated at or near the Upsilon(4S) resonance, using the Belle detector at the e+ e- asymmetric-energy collider KEKB. The integrated luminosity of the data sample used is 461.5 fb(-1).

Journal Article↗
PubMed2006

Observation of a near-threshold D(0)D[over](0)pi(0) enhancement in B-->D(0)D[over](0)pi(0)Kappa decay.

We report the first observation of a near-threshold enhancement in the D(0)D[over](0)pi(0) system from B-->D(0)D[over](0)pi(0)Kappa decays using a 414 fb(-1) data sample collected at the Upsilon(4S) resonance. The enhancement peaks at a mass M=3875.2+/-0.7(+0.3)/(-1.6) +/-0.8 MeV/c2 and the branching fraction for events in the peak is B(B-->D(0)D[over](0)pi(0)Kappa)=(1.22+/-0.31(+0.23)/(-0.30))x10(-4). The data were collected with the Belle detector at the KEKB energy-asymmetric e+ e- collider.

Journal Article↗
PubMed2006

Persistent elevation of serum alanine aminotransferase levels leads to poor survival and hepatocellular carcinoma development in type 1 autoimmune hepatitis.

BACKGROUND: Although the prognosis of type 1 autoimmune hepatitis is generally good with immunosuppressive treatment, the disease progresses in some patients despite the treatment. The prognosis may be determined by the clinical course. AIM: To evaluate the long-term prognosis and assess the predictive factors for a serious event, including the development of hepatocellular carcinoma or death. METHODS: Sixty-nine patients with type 1 autoimmune hepatitis were prospectively followed up regularly, with a median follow-up period of 96 months (49-201 months). RESULTS: During the follow-up period, three patients (4%) developed hepatocellular carcinoma, and two of these three patients died. Another patient died of liver failure. The 10-year survival rate was 98%, and the 10-year hepatocellular carcinoma-free rate was 93%. The four patients experiencing a serious event received higher maintenance doses of corticosteroid during their follow-up periods than those did not. However, serum alanine aminotransferase levels during the follow-up period were higher in these four patients than in the others. CONCLUSIONS: Persistent elevation of serum alanine amniotransferase levels during the follow-up period, rather than factors existing prior to medical treatment is considered to be an important prognostic factor, and it is indicated that poor outcomes may result from the resistance to immunosuppressive treatment.

Adolescent↗
PubMed2006

Efficacy and safety of adeno-associated viral vectors based on serotype 8 and 9 vs. lentiviral vectors for hemophilia B gene therapy.

BACKGROUND: Adeno-associated viral (AAV) and lentiviral vectors are promising vectors for gene therapy for hemophilia because they are devoid of viral genes and have the potential for long-term gene expression. OBJECTIVES: To compare the performance of different AAV serotypes (AAV8 and AAV9) vs. lentiviral vectors expressing factor (F) IX. METHODS AND RESULTS: AAV-based and lentiviral vectors were generated that express FIX from the same hepatocyte-specific expression cassette. AAV9 transduced the liver as efficiently as AAV8 and resulted in supra-physiological FIX levels (3000-6000% of normal) stably correcting the bleeding diathesis. Surprisingly, AAV9 resulted in unprecedented and widespread cardiac gene transfer, which was more efficient than with AAV8. AAV8 and AAV9 were not associated with any proinflammatory cytokine induction, in accordance with their minimal interactions with innate immune effectors. In contrast, lentiviral transduction resulted in modest and stable FIX levels near the therapeutic threshold (1%) and triggered a rapid self-limiting proinflammatory response (interleukin-6), which probably reflected their ability to efficiently interact with the innate immune system. CONCLUSIONS: AAV8 and 9 result in significantly higher FIX expression levels and have a reduced proinflammatory risk in comparison with lentiviral vectors. The unexpected cardiotropic properties of AAV9 have implications for gene therapy for heart disease.

Animals↗
PubMed2006

Gene therapy of liver tumors with human liver-specific nanoparticles.

The development of safe and efficient liver-specific gene delivery approaches offers new perspectives for the treatment of liver disease, in particular, liver cancer. We evaluated the therapeutic potential of hepatotropic nanoparticles for gene therapy of liver tumor. These nanoparticles do not contain a viral genome and display the hepatitis B virus L antigen, which is essential to confer hepatic specificity. It has not been shown whether a therapeutic effect could be obtained using L nanoparticles in a human liver tumor xenograft model. Rats bearing human hepatic (NuE) and non-hepatic tumors were injected with L nanoparticles containing a green fluorescent protein (GFP) expression plasmid. GFP expression was observed only in NuE-derived tumors but not in the non-hepatic tumor. The potential for treatment of liver tumors was analyzed using L nanoparticles containing the herpes simplex virus thymidine kinase gene, in conjunction with ganciclovir pro-drug administration. The growth of NuE-derived tumors in L particle-injected rats was significantly suppressed, but not of the non-hepatic tumor control. In summary, this is the first demonstration that nanoparticles could be used for delivery of therapeutic genes with anti-tumor activity into human liver tumors. This intravenous delivery system may be one of the major advantages as compared to many other viral vector systems.

Animals↗
PubMed2006

Measurement of the quark mixing parameter cos2phi1 using time-dependent Dalitz analysis of B0 -->D[KS(0)pi + pi-]h0.

We present a measurement of the angle phi1 of the Cabibbo-Kobayashi-Maskawa unitarity triangle using a time-dependent Dalitz analysis of D-->KS(0)pi + pi- decays produced in neutral B meson decay to a neutral D meson and a light meson (B0-->D*h0). The method allows a direct extraction of 2phi1 and, therefore, helps to resolve the ambiguity between 2phi1 and pi-2phi1 in the measurement of sin2phi1. We obtain sin2phi1= 0.78 +/- 0.44 +/- 0.22 and cos2varphi1 = 1.87(-0.53-0.32)(+0.40 + 0.22). The sign of cos2phi1 is determined to be positive at 98.3% C.L.

Journal Article↗
PubMed2006

Measurement of D0-->pilnu(Klnu) form factors and absolute branching fractions.

Using a 282 fb-1 data sample collected by the Belle experiment at the KEKB e+e- collider, we study D0 decays to K-l+nu and pi-l+nu final states. The D0 flavor and momentum are tagged through a full reconstruction of the recoiling charm meson and additional mesons from fragmentation. The reconstruction method provides very good resolution in neutrino momentum and in q2=(pl+pnu)2. Normalizing to the total number of D0 tags, we measure the absolute branching fractions to be B(D0-->Klnu)=(3.45+/-0.07stat+/-0.20syst)% and B(D0-->pilnu)=(0.255+/-0.019stat+/-0.016syst)% and the semileptonic form factors (within the modified pole model) f+K(0)=0.695+/-0.007stat+/-0.022syst and f+pi(0)=0.624+/-0.020stat+/-0.030syst.

Journal Article↗
PubMed2006

Evidence for B-->eta'pi and improved measurements for B-->eta'K.

We report evidence for the exclusive two-body charmless hadronic B meson decay B-->eta'pi, and improved measurements of B-->eta'K. The results are obtained from a data sample of 386x10(6) BB pairs collected at the Upsilon(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e+e- collider. We measure B(B+-->eta'pi+)=[1.76(-0.62)(+0.67)(stat)(-0.14)(+0.15)(syst)]x10(-6) and B(B0-->eta'pi0)=[2.79(-0.96)(+1.02)(stat)(-0.34)(+0.25)(syst)]x10(-6). We also find the ratio of B(B+-->eta'K+)/B(B0-->eta'K0)=1.17+/-0.08(stat)+/-0.03(syst) and measure the direct CP asymmetries for the charged modes.

Journal Article↗
PubMed2006

Clinical features of Japanese male patients with type 1 autoimmune hepatitis.

BACKGROUND: Recently, unusual patients with autoimmune hepatitis, such as male patients, have increased. AIM: To assess clinical feature of Japanese males with type 1 autoimmune hepatitis compared with females. METHODS: We investigated consecutive 160 patients with type 1 autoimmune hepatitis, who consisted of 20 males and 140 females, with a median age of 55 (16-79) years. RESULTS: Compared with females, males had a lower frequency of definite diagnosis according to the revised scoring system proposed by the International Autoimmune Hepatitis Group (40% vs. 85%) and lower serum levels of immunoglobulin G [1932 (1085-3850) mg/dL vs. 2624 (1354-6562) mg/dL]. However, they were similar in age, form of clinical onset, symptomatic concurrent autoimmune disease, human leucocyte antigen DR status and frequency of cirrhosis at the time of diagnosis. The normalization of serum alanine aminotransferase levels within 6 months after the introduction of corticosteroid treatment was lower in males compared with females (73% vs. 93%). CONCLUSIONS: In male patients, a diagnosis of autoimmune hepatitis should be made carefully. In Japanese patients with a dominant frequency of human leucocyte antigen DR4, gender may affect the response to corticosteroid treatment.

Adolescent↗
PubMed2006

Evidence for large direct CP violation in B+/- --> rho(770)0K+/- from analysis of three-body charmless B+/- --> K+/-pi+/-pi+/- decays.

We report results on a Dalitz analysis of three-body charmless B+/- --> K+/-pi+/-pi+/- decay including searches for direct CP violation. We report the first observation of the decay B+/- --> f2(1270)K+/- with a statistical significance above 6sigma. We also observe first evidence for large direct CP violation in the B+/- --> rho(770)0K+/- channel. The results are obtained with a data sample that contains 386 10(6) BB pairs collected at the Y(4s) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

Journal Article↗
PubMed2006

Stromal cell-derived factor-1 and CXCR4 receptor interaction in tumor growth and metastasis of breast cancer.

Stromal cell-derived factor-1 (SDF-1)/CXCR4 interaction is critical for the trafficking of lymphocytes, homing and retention of hematopoietic stem cells within the bone marrow and is essential in fetal hematopoiesis. Binding of SDF-1 to CXCR4 activates a variety of intracellular signal transduction pathways and effector molecules that regulate cell survival, proliferation, chemotaxis, migration and adhesion. Recently, intensive research has demonstrated that SDF-1/CXCR4 interaction also regulates several key events in wide variety of cancers. Serum-depleted media in the presence of SDF-1 protected the breast cancer cells from apoptosis. CXCR4-low-expressing MCF-7 formed small tumor at inoculated site in SCID mice 8-9 weeks after inoculation while completely failed to metastasis into various organs. In contrast, CXCR4-high-expressing MDA-231 cells were most efficient in the formation of a large tumor and organ-metastasis within 3 weeks in SCID mice. This review briefly focuses on the role of SDF-1/CXCR4 interaction in tumor growth and metastasis of breast cancer cell both in vitro and in vivo.

Animals↗
PubMed2006

Measurement of forward-backward asymmetry and Wilson coefficients in B --> K*l+l-.

We report the first measurement of the forward-backward asymmetry and the ratios of Wilson coefficients and in A9/A7 and A10/A7 in B --> K*l+l-, where l represents an electron or a muon. We find evidence for the forward-backward asymmetry with a significance of 3.4sigma. The results are obtained from a data sample containing 386 x 10(6) BB pairs that were collected on the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

Journal Article↗
PubMed2006

Measurement of azimuthal asymmetries in inclusive production of hadron pairs in e(+)e(-) annihilation at Belle.

The Collins effect connects transverse quark spin with a measurable azimuthal dependence in the yield of hadronic fragments around the quark's momentum vector. Using two different reconstruction methods, we find evidence of statistically significant azimuthal asymmetries for charged pion pairs in e(+)e(-) annihilation at a center-of-mass energy of 10.52 GeV, which can be attributed to a transverse polarization of the primordial quarks. The measurement was performed using a sample of 79 x 10(6) hadronic events collected with the Belle detector.

Journal Article↗
PubMed2006

Observation of b-->dgamma and determination of /Vtd/Vts/.

We report the observation of the flavor-changing neutral current process b-->dgamma using a sample of 386 x 106 B meson pairs accumulated by the Belle detector at the KEKB e+e- collider. We measure branching fractions for the exclusive modes B--->rho-gamma, B0rho0gamma, and B0omegagamma. Assuming that these three modes are related by isospin, we find B(B-->(rho,gamma)gamma)=[Formula: See Text] with a significance of 5.1sigma. This result is used to determine the ratio of Cabibbo-Kobayashi-Maskawa matrix elements /Vtd/Vts/ to be [Formula: See Text].

Journal Article↗