Biomedical subjects

M Iwasaki

Publications and source records attributed to M Iwasaki.

At least 73 records · Page 4Linked to original sources

PubMed2004

Measurements of the D(sJ) resonance properties.

We report measurements of the properties of the D(+)(sJ)(2317) and D(+)(sJ)(2457) resonances produced in continuum e(+)e(-) annihilation near sqrt[s]=10.6 GeV. The analysis is based on an 86.9 fb(-1) data sample collected with the Belle detector at KEKB. We determine the masses to be M(D(+)(sJ)(2317))=2317.2+/-0.5(stat)+/-0.9(syst) MeV/c(2) and M(D(+)(sJ)(2457))=2456.5+/-1.3(stat)+/-1.3(syst) MeV/c(2). We observe the radiative decay mode D(+)(sJ)(2457)-->D(+)(s)gamma and the dipion decay mode D(+)(sJ)(2457)-->D(+)(s)pi(+)pi(-) and determine their branching fractions. No corresponding decays are observed for the D(sJ)(2317) state. These results are consistent with the spin-parity assignments of 0(+) for the D(sJ)(2317) and 1(+) for the D(sJ)(2457).

Journal Article↗

PubMed2004

Neuromagnetic separation of secondarily bilateral synchronized spike foci: report of three cases.

To demonstrate the high spatiotemporal resolution of magnetoencephalography (MEG), we report three cases with focal epilepsy that exhibited bilateral synchronized spikes on simultaneous scalp EEG and MEG recording. Constant time lags (19.4 +/- 3.0 ms and 20.0 +/- 5.5) between the leading and the following contralateral spikes were noted on MEG and the current dipole sources were localized in the bilateral homotopic regions symmetrically in Cases 1 and 3. In Case 2, MEG indicated leading spikes in the left frontal region, with a time lag of 42.3 +/- 8.4 ms to reach the contralateral frontal and bilateral temporal regions as well. Chronic subdural EEG recording in Cases 1 and 2 confirmed that the leading spike focus in MEG was close to the seizure onset zone in cortical EEG. Spatio-temporal analysis of MEG spikes may be useful to identify the primary epileptic region in patients with synchronized bilateral epileptiform discharges.

Adolescent↗

PubMed2004

Chemical induction of HO-1 suppresses lupus nephritis by reducing local iNOS expression and synthesis of anti-dsDNA antibody.

There is accumulating evidence that haem oxygenase (HO)-1 plays a protective role in various disorders. The beneficial efficacy of HO-1 induction therapy has been shown in renal diseases such as glomerulonephritis, interstitial nephritis and drug induced nephrotoxicity. However, involvement of HO-1 in the development of autoimmune renal diseases remains uncertain. To assess the clinical efficacy of HO-1 induction therapy for lupus glomerulonephritis, MRL/lpr mice were intraperitoneally injected with 100 micromol/kg hemin, a potent HO-1 inducer, or PBS as controls, once a week from 6 weeks of age to 21-24 weeks-old. We found that treatment with hemin led to a significant reduction of proteinuria and remarkable amelioration of glomerular lesions accompanied by decreased immune depositions. In addition, the circulating IgG anti-double-stranded DNA antibody level was significantly decreased in hemin treated mice when compared with controls. A single intraperitoneal injection with hemin resulted in reduction of inducible nitric oxide synthase expression in the kidney and spleen, and serum interferon-gamma level. Our results suggest that HO-1 induction therapy ameliorates lupus nephritis by suppressing nitric oxide (NO) dependent inflammatory responses and attenuating production of pathogenic autoantibodies.

Animals↗

PubMed2003

Measurement of time-dependent CP-violating asymmetries in B0-->phiK(0)S, K+K-K0(S), and eta'K0(S) decays.

We present an improved measurement of CP-violation parameters in B0-->phiK(0)(S), K(+)K(-)K(0)(S), and eta(')K(0)(S) decays based on a 140 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider. One neutral B meson is fully reconstructed in one of the specified decay channels, and the flavor of the accompanying B meson is identified from its decay products. CP-violation parameters for each of the three modes are obtained from the asymmetries in the distributions of the proper-time intervals between the two B decays. We find that the observed CP asymmetry in the B-->phiK(0)(S) decay differs from the standard model (SM) expectation by 3.5 standard deviations, while the other cases are consistent with the SM.

Journal Article↗

PubMed2003

Observation of the D(sJ)(2317) and D(sJ)(2457) in B decays.

We report the first observation of the B-->Dmacr;D(sJ)(2317) and B-->Dmacr;D(sJ)(2457) decays based on 123.8x10(6) BBmacr; events collected with the Belle detector at KEKB. We observe the D(sJ)(2317) decay to D(s)pi(0) and the D(sJ)(2457) decay to the D(*)(s)pi(0) and D(s)gamma final states. We also set 90% C.L. upper limits for the decays D(sJ)(2317)-->D(*)(s)gamma, D(sJ)(2457)-->D(*)(s)gamma, D(sJ)(2457)-->D(s)pi(0), and D(sJ)(2457)-->D(s)pi(+)pi(-).

Journal Article↗

PubMed2003

Observation of B-->K*l+l-.

We report the observation of the flavor-changing neutral current decay B-->K(*)l(+)l(-) and an im-proved measurement of the decay B-->Kl(+)l(-), where l represents an electron or a muon, with a data sample of 140 fb(-1) accumulated at the Upsilon(4S) resonance with the Belle detector at KEKB. The results for the branching fractions are B(B-->K(*)l(+)l(-))=(11.5(+2.6)(-2.4)+/-0.8+/-0.2)x10(-7) and B(B-->Kl(+)l(-))=(4.8(+1.0)(-0.9)+/-0.3+/-0.1)x10(-7), where the first error is statistical, the second is systematic and the third is from model dependence.

Journal Article↗

PubMed2003

Evidence for B0-->pi0pi0.

We report evidence for the decay B0-->pi(0)pi(0). The analysis is based on a data sample of 152x10(6) BBmacr; pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) storage ring. We detect a signal for B0-->pi(0)pi(0) with a significance of 3.4 standard deviations, and measure the branching fraction to be [1.7+/-0.6(stat)+/-0.2(syst)]x10(-6).

Journal Article↗

PubMed2003

Observation of a narrow charmoniumlike state in exclusive B+/--->K+/-pi+pi-J/psi decays.

We report the observation of a narrow charmoniumlike state produced in the exclusive decay process B+/--->K+/-pi(+)pi(-)J/psi. This state, which decays into pi(+)pi(-)J/psi, has a mass of 3872.0+/-0.6(stat)+/-0.5(syst) MeV, a value that is very near the M(D0)+M(D(*0)) mass threshold. The results are based on an analysis of 152M B-Bmacr; events collected at the Upsilon(4S) resonance in the Belle detector at the KEKB collider. The signal has a statistical significance that is in excess of 10sigma.

Journal Article↗

PubMed2003

Observation of B-/+-->rho-/+rho0 decays.

We report the first observation of the charmless vector-vector decay process B-/+-->rho(-/+)rho(0). The measurement uses a 78 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric e(+)e(-) collider operating at the Upsilon(4S) resonance. We obtain a branching fraction of B(B-/+-->rho(-/+)rho(0))=[31.7+/-7.1(stat)+3.8-6.7(syst)]x10(-6). An analysis of the rho helicity-angle distributions gives a longitudinal polarization fraction of Gamma(L)/Gamma=0.95+/-0.11(stat)+/-0.02(syst). We also measure the direct-CP-violating asymmetry A(CP)(B-/+-->rho(-/+)rho(0))=0.00+/-0.22(stat)+/-0.03(syst).

Journal Article↗

PubMed2003

High frequency of antibiotic-associated diarrhea due to toxin A-negative, toxin B-positive Clostridium difficile in a hospital in Japan and risk factors for infection.

Patients hospitalized in a hospital with a high incidence of antibiotic-associated diarrhea due to toxin A-negative, toxin B-positive (A-/B+) Clostridium difficile were retrospectively investigated to determine the clinical manifestations and risk factors for infection. Of 77 Clostridium difficile isolates obtained from 77 patients during the 1-year investigation period, 30 were A-/B+ and 47 were toxin A-positive, toxin B-positive (A+/B+). By pulsed-field gel electrophoresis analysis, 23 of the 30 A-/B+ strains were outbreak-related, suggesting nosocomial spread of a single type of bacterium, which mainly affected patients in the wards of respiratory medicine, hematology and neurology. Using regression analysis, three factors were found to be associated with infection by A-/B+ isolates: (i) exposure to antineoplastic agents ( P=0.01, odds ratio [OR]=5.1), (ii) the use of nasal feeding tubes ( P=0.008, OR=5.2), and (iii) assignment to a certain internal medicine ward ( P=0.05, OR=3.0). Between patients with Clostridium difficile-associated diarrhea caused by A-/B+ strains and those with A+/B+ strains, no statistically significant difference was found in body temperature, serum concentration of C-reactive protein, leukocyte count in whole blood, frequency of diarrhea, or type of underlying disease. These results indicate that A-/B+ strains of Clostridium difficile can cause intestinal infection in humans and they spread nosocomially in the same manner as A+/B+ strains.

Adolescent↗

PubMed2003

Improved direct measurement of the parity-violation parameter Ab using a mass tag and momentum-weighted track charge.

We present an improved direct measurement of the parity-violation parameter A(b) in the Z boson-b-quark coupling using a self-calibrating track-charge technique applied to a sample enriched in Z-->bb events via the topological reconstruction of the B hadron mass. Manipulation of the Stanford Linear Collider electron-beam polarization permits the measurement of A(b) to be made independently of other Z-pole coupling parameters. From the 1996-1998 sample of 400,000 hadronic Z decays, produced with an average beam polarization of 73.4%, we find A(b)=0.906+/-0.022(stat)+/-0.023(syst).

Journal Article↗

PubMed2003

Expression and distribution of transcripts for sonic hedgehog in the early phase of fracture repair.

Localization and expression of mRNAs for sonic hedgehog (Shh) at a fracture site in the early phase postfracture were investigated by in situ hybridization and reverse transcription and polymerase chain reaction (RT-PCR). A closed fracture was made in the midshaft of the right tibia of 5-week-old ICR mice, and fractured sites were harvested prefracture (day 0) and on days 2 and 12. In situ hybridization revealed that transcripts for Shh were not detected on day 0, but they were detected in proliferating callus-forming cells in the periosteum and the surrounding tissue, and in the medullary cavity prior to apparent new cartilage and bone formation. Gli 1 (a signaling mediator for Shh) and bone morphogenetic protein-4 transcripts were colocalized with those for Shh transcripts on day 2. The RT-PCR showed that Shh mRNA was detected in the PCR product from day 2, but not from days 0 and 12. These findings are the first description about the activation of Shh gene in the early postfracture reaction.

Animals↗

PubMed2003

Adsorption of thiolates to singly coordinated sites on Au111 evidenced by photoelectron diffraction.

The adsorption structure of methylthiolate (CH3S) adsorbed on Au(111), a long-standing controversial issue, has been unambiguously determined by scanned-energy and scanned-angle S 2p photoelectron diffraction. The methylthiolate molecules are found to occupy atop sites with a S-Au distance of 2.42 +/- 0.03 A. The angular distribution of the S 2p photoelectrons due to forward scattering reveals that the S-C bond is inclined by approximately 50 degrees from the surface normal towards both the [211] and [121] (nearest-neighbor thiolate) directions.

Journal Article↗

PubMed2003

Masticatory laterality--evaluation and influence of food texture.

The purpose of this study is the objective and quantitative evaluation of masticatory laterality and its daily variability. Various foods with different textures were used to investigate whether food texture influenced masticatory laterality. Ten healthy subjects and seven foods were used. Recordings of chewing movements were repeated three times at intervals of 1 week. Masticatory laterality was assessed with an Asymmetry Index [AI: (number of right side strokes - number of left side strokes)/number of total strokes]. Medians and ranges of the three recordings were calculated. The observed AI ranges in the three trials were limited with the exception of two subjects. Among the other subjects, averages of the absolute values of the medians were from 32.5 to 73.4%. Statistically significant differences between the hardest food and softer foods were observed in absolute value of AI medians. Masticatory laterality could be evaluated by an AI. Eight of 10 subjects showed limited ranges of AI in three recordings. It should be noted that a few people actually chew on either side but might chew on one side only on a particular day. Hard food evoked more masticatory laterality, and seemed more appropriate for laterality examinations.

Adult↗

PubMed2003

Analyses of absorbed dose to tooth enamel against external photon exposure.

Absorbed dose to tooth enamel was examined against external photon exposure by measurements with thermoluminescence dosemeters (TLDs) and Monte Carlo calculations. TLDs were placed in a realistic physical phantom to measure dose to the teeth region in a head. A voxel-type phantom was constructed from computed tomography (CT) images of the physical phantom. Monte Carlo calculations with this voxel-type phantom were performed to analyse the results of the experiments. The data obtained were compared to the enamel doses, which were calculated with a modified MIRD-type phantom and already given in a previous paper. It was confirmed that the data derived with the MIRD-type phantom are applicable for retrospective individual dose assessments by electron spin resonance (ESR) dosimetry using teeth for the photon energy region above 300 keV. The analysis, however, indicated that the configuration of the head can affect the enamel dose relative to external exposure to photons with energy below 100 keV.

Calibration↗

PubMed2002

Measurement of the positive muon anomalous magnetic moment to 0.7 ppm.

A higher precision measurement of the anomalous g value, a(mu)=(g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron, based on data collected in the year 2000. The result a(mu(+))=11 659 204(7)(5)x10(-10) (0.7 ppm) is in good agreement with previous measurements and has an error about one-half that of the combined previous data. The present world average experimental value is a(mu)(expt)=11 659 203(8)x10(-10) (0.7 ppm).

Journal Article↗

PubMed2002

Improved direct measurement of A(b) and A(c) at the Z(0) pole using a lepton tag.

The parity violation parameters A(b) and A(c) of the Zb(b) and Zc(c) couplings have been measured directly, using the polar angle dependence of the polarized cross sections at the Z(0) pole. Bottom and charmed hadrons were tagged via their semileptonic decays. Both the electron and muon analyses take advantage of new multivariate techniques to increase the analyzing power. Based on the 1993-1998 SLD sample of 550,000 Z(0) decays produced with highly polarized electron beams, we measure A(b) = 0.919+/-0.030(stat)+/-0.024(syst), and A(c) = 0.583+/-0.055(stat)+/-0.055(syst).

Journal Article↗

PubMed2002

Deeply bound 1s and 2p pionic states in 205Pb and determination of the s-wave part of the pion-nucleus interaction.

We observed well-separated 1s and 2p pi(-) states in 205Pb in the 206Pb(d,3He) reaction at T(d) = 604.3 MeV. The binding energies and the widths determined are B(1s) = 6.762+/-0.061 MeV, Gamma(1s) = 0.764(+0.154)(-0.171) MeV, B(2p) = 5.110+/-0.045 MeV, and Gamma(2p) = 0.321(-0.062)(+0.060) MeV. They are used to deduce the real and imaginary strengths of the s-wave part of the pion-nucleus interaction, which translates into a positive mass shift of pi(-) in 205Pb.

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