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Biomedical subjects

K Nishikawa

Publications and source records attributed to K Nishikawa.

At least 19 recordsLinked to original sources
PubMed2006

Measurement of atmospheric neutrino flux consistent with tau neutrino appearance.

A search for the appearance of tau neutrinos from nu(mu) <--> nu(tau) oscillations in the atmospheric neutrinos has been performed using 1489.2 days of atmospheric neutrino data from the Super-Kamiokande-I experiment. A best fit tau neutrino appearance signal of 138+/-48(stat)-32(+15)(syst) events is obtained with an expectation of 78+/-26(syst). The hypothesis of no tau neutrino appearance is disfavored by 2.4 sigma.

Journal Article↗
PubMed2006

Study on purification mechanism in soil penetration facility for effluents from urban area and control strategies.

In this study, demonstration experiments for removal of pollutants from road surface runoff during storm events were carried out under natural conditions in an outdoor pilot-scale soil penetration facility. In general, soil retains suspended matter and removes dissolved matter by adsorption. However, issues such as reduced purification capacity resulting from clogging and recovery of purification capacity during periods of intermittent supply of the storm water affect the removal efficiency of pollutants. Therefore, this study aimed at clarifying purification mechanisms during storm events and understanding how the structural characteristics of the soil penetration facility affect purification capacity based on long-term continuous measurements. In addition, modeling the purification mechanism under changing characteristics of rainfall in the long-term was undertaken.

Adsorption↗
PubMed2005

Bactericidal effects of plasma-generated cluster ions.

Air purification by plasma-generated cluster ions (PCIs) relies on a novel technology producing hydrated positive and negative ions. Phenomenological tests have shown strong evidence of lethal effects of the PCIs on various micro-organisms. However, the mechanisms of PCI action are still widely unknown. The aim was thus to test the bactericidal efficacy of PCI technology on common indoor micro-organisms and to explore possible PCI mechanisms of action. According to time/dose-dependent experiments with Staphylococcus, Enterococcus, Micrococcus and Bacillus, the inhibiting effects became apparent within the first few minutes of PCI exposure and led to an irreversible 99.9% destruction within the following 2-8 h of exposure. The destructive effect of the PCIs corresponded to membrane damage of the bacteria. Use of the techniques of both SDS PAGE and 2D PAGE revealed changes in the bacterial surface protein composition induced by the PCIs. In contrast, neither DNA nor cytoplasm protein damage was detected electrophoretically. The antimicrobial action of the PCIs seems to occur because of chemical modification of the surface proteins of bacteria. In situ hydroxyl radical formation on the surface of bacteria was proposed as the leading mechanism of the protein damage caused by the PCIs. At the same time, DNA damage seems not to be involved in the antibacterial action of the PCIs. The data obtained would broaden the knowledge concerning the antibacterial effects of air-born plasma-generated cluster ions and help to produce more efficient air-cleaning devices.

Air Ionization↗
PubMed2005

Mutational effect for stability in a conserved region of thermolysin.

AIMS: To investigate the mutational effect for the stability of thermolysin (TLN) in conserved regions. METHODS AND RESULTS: Mutational effects for stability at autodegradation sites of TLN in conserved region were studied. The bands of mutant TLN (34 kDa) on SDS-PAGE were decreased. However, those of mutant TLN cultivated with CaCl2 recovered to the same level as WT TLN. Dialysis study shows that these mutant TLN require more calcium ions than WT TLN. CONCLUSIONS: From these results, calcium affinity of mutant TLN in the conserved regions seem to become weak, subsequently mutant TLN were easily autodegraded in the case of low concentration of CaCl2. SIGNIFICANCE AND IMPACT OF THE STUDY: The autodegradation sites located in conserved regions of bacilli neutral proteases are important for the tertiary structure formation concerning the stability of the protein.

Amino Acid Sequence↗
PubMed2005

Identification of RAI3 as a therapeutic target for breast cancer.

We have been investigating gene-expression profiles in estrogen receptor (ER)-negative breast cancers to identify molecules involved in breast carcinogenesis and to select genes or gene products that might be useful as diagnostic markers or targets for new molecular therapies. Here we report evidence that the gene encoding retinoic acid-induced protein 3 (RAI3) is a potential molecular target for treatment of breast cancers. Using quantitative reverse transcription-PCR (RT-PCR), we documented increased expression of RAI3 in 19 of 25 primary breast cancers and in 6 of 11 breast-cancer cell lines examined, by comparison with normal mammary-gland tissue. Treatment of human embryonic kidney (HEK293) cells with siRNA against RAI3 suppressed expression of RAI3 and also suppressed cell growth. Transfection of siRNA into breast-cancer cell lines MCF7 and T47D also suppressed RAI3 mRNA and growth of the cancer cells. Because our data imply that up-regulation of RAI3 function is a frequent feature of breast carcinogenesis, we suggest that selective suppression of signal from RAI3 might hold promise for development of a new strategy for treating breast cancers.

Breast Neoplasms↗
PubMed2004

Evidence for an oscillatory signature in atmospheric neutrino oscillations.

Muon neutrino disappearance probability as a function of neutrino flight length L over neutrino energy E was studied. A dip in the L/E distribution was observed in the data, as predicted from the sinusoidal flavor transition probability of neutrino oscillation. The observed L/E distribution constrained nu(micro)<-->nu(tau) neutrino oscillation parameters; 1.9x10(-3) 0.90 at 90% confidence level.

Journal Article↗
PubMed2004

Search for electron neutrino appearance in a 250 km long-baseline experiment.

We present a search for electron neutrino appearance from accelerator-produced muon neutrinos in the K2K long-baseline neutrino experiment. One candidate event is found in the data corresponding to an exposure of 4.8 x 10(19) protons on target. The expected background in the absence of neutrino oscillations is estimated to be 2.4+/-0.6 events and is dominated by misidentification of events from neutral current pi(0) production. We exclude the nu(micro) to nu(e) oscillations at 90% C.L. for the effective mixing angle in the 2-flavor approximation of sin((2)2theta(microe)( approximately 1/2sin((2)2theta(13))>0.15 at Deltam(2)(microe)=2.8 x 10(-3) eV(2), the best-fit value of the nu(micro) disappearance analysis in K2K. The most stringent limit of sin((2)2theta(microe)<0.09 is obtained at Deltam(2)(microe)=6 x 10(-3) eV(2).

Journal Article↗
PubMed2004

Limits on the neutrino magnetic moment using 1496 days of Super-Kamiokande-I solar neutrino data.

A search for a nonzero neutrino magnetic moment has been conducted using 1496 live days of solar neutrino data from Super-Kamiokande-I. Specifically, we searched for distortions to the energy spectrum of recoil electrons arising from magnetic scattering due to a nonzero neutrino magnetic moment. In the absence of a clear signal, we found micro(nu)</=(3.6x10(-10))micro(B) at 90% C.L. by fitting to the Super-Kamiokande day-night spectra. The fitting took into account the effect of neutrino oscillation on the shapes of energy spectra. With additional information from other solar neutrino and KamLAND experiments constraining the oscillation region, a limit of micro(nu)</=(1.1x10(-10))micro(B) at 90% C.L. was obtained.

Journal Article↗
PubMed2004

Recovery characteristics and post-operative delirium after long-duration laparoscope-assisted surgery in elderly patients: propofol-based vs. sevoflurane-based anesthesia.

BACKGROUND: Post-operative mental dysfunction may be an important problem in elderly patients. This study was designed to compare the effects of propofol and sevoflurane anesthesia on recovery characteristics and the incidence of post-operative delirium (POD) in long-duration laparoscopic surgery for elderly patients. METHODS: Fifty ASA physical status I-II patients over the age of 65 scheduled for laparoscopic surgery lasting 3 h or more randomly received propofol (group P, n = 25) or sevoflurane (group S, n = 25) for both induction and maintenance of general anesthesia. Both groups were combined with continuous perioperative epidural analgesia. The level of primary anesthetics was adjusted to maintain changes in mean arterial pressure within 20% of the pre-anesthetic values. The emergence times from anesthesia (eye opening, extubation, response to command, and orientation) were recorded, and the occurrence of POD was assessed by the delirium rating scale (DRS) during the first 3 days after surgery. All patients received oxygen and continuous epidural analgesia postoperatively. RESULTS: Immediate emergence, i.e. eye opening and extubation was significantly faster after sevoflurane (P < 0.05). There was no significant difference between the incidences of POD in the two groups during the first 3 days after surgery. The scores for DRS on day 2 and 3 after surgery, however, were significantly higher in group P than in group S (P < 0.01). CONCLUSION: Sevoflurane may be preferable to propofol for general anesthesia in combination with epidural analgesia with respect to less effect on mental function during the early postoperative period for long-duration laparoscopic surgery in elderly patients.

Aged↗
PubMed2004

Left ventricular mechanical performance in elderly patients after induction of anaesthesia. A comparison of inhalational induction with sevoflurane and intravenous induction with fentanyl and propofol.

We investigated changes in left ventricular mechanical performance in 40 patients aged > 70 years in whom anaesthesia had been induced with sevoflurane or with fentanyl and propofol. The ratio of ventricular contractility to arterial properties, which reflects left ventricular performance, was estimated from the ratio of ventricular end-systolic elastance to effective arterial elastance. This ratio decreased after induction in both groups, the magnitude of the decrease being significantly greater in the fentanyl/propofol group than in the sevoflurane group. Decreases in mean arterial pressure after induction of anaesthesia in the two groups were similar, whereas the magnitude of the decrease in heart rate in the sevoflurane group was greater than that in the fentanyl/propofol group. Sevoflurane may therefore be preferable to fentanyl and propofol for induction of anaesthesia in elderly patients because of its lesser effect on left ventricular performance.

Aged↗
PubMed2004

Airway problems related to laryngeal mask airway use associated with an undiagnosed epiglottic cyst.

This report describes airway management difficulties in a patient with an asymptomatic and undiagnosed epiglottic cyst. Mask ventilation after induction of general anesthesia was uneventful. Insertion of an LMA resulted in inadequate ventilation. Fiberoptic intubation through an intubating LMA was impossible because the LMA pushed the cyst into the laryngeal inlet. Fibreoptic intubation, assisted by the use of a direct laryngoscope without the LMA was uneventful. Preoperative craniocervical scans performed for assessment of other conditions may reveal asymptomatic pathology in the airway.

Airway Obstruction↗
PubMed2003

Search for nu(e) from the sun at Super-Kamiokande-I.

We present the results of a search for low energy nu(e) from the Sun using 1496 days of data from Super-Kamiokande-I. We observe no significant excess of events and set an upper limit for the conversion probability to nu(e) of the 8B solar neutrino. This conversion limit is 0.8% (90% C.L.) of the standard solar model's neutrino flux for total energy=8-20 MeV. We also set a flux limit for monochromatic nu(e) for E(nu(e))=10-17 MeV.

Journal Article↗
PubMed2003

Anomalous resistivity resulting from MeV-electron transport in overdense plasma.

Laser produced hot electron transport in an overdense plasma is studied by three-dimensional particle-in-cell simulations. Hot electron currents into the plasma generate neutralizing return currents in the cold plasma electrons, leading to a configuration which is unstable to electromagnetic Weibel and tearing instabilities. The resulting current filaments self-organize through a coalescence process finally settling into a single global current channel. The plasma return current experiences a strong anomalous resistivity due to diffusive flow of cold electrons in the magnetic perturbations. The resulting electrostatic field leads to an anomalously rapid stopping of fast MeV electrons (almost 3 orders of magnitude stronger than that through classical collisional effects).

Journal Article↗
PubMed2003

Search for supernova relic neutrinos at Super-Kamiokande.

A search for the relic neutrinos from all past core-collapse supernovae was conducted using 1496 days of data from the Super-Kamiokande detector. This analysis looked for electron-type antineutrinos that had produced a positron with an energy greater than 18 MeV. In the absence of a signal, 90% C.L. upper limits on the total flux were set for several theoretical models; these limits ranged from 20 to 130 macro nu(e) cm(-2) s(-1). Additionally, an upper bound of 1.2 macro nu(e) cm(-2) s(-1) was set for the supernova relic neutrino flux in the energy region E(nu)>19.3 MeV.

Journal Article↗
PubMed2003

Indications of neutrino oscillation in a 250 km long-baseline experiment.

The K2K experiment observes indications of neutrino oscillation: a reduction of nu(mu) flux together with a distortion of the energy spectrum. Fifty-six beam neutrino events are observed in Super-Kamiokande (SK), 250 km from the neutrino production point, with an expectation of 80.1(+6.2)(-5.4). Twenty-nine one ring mu-like events are used to reconstruct the neutrino energy spectrum, which is better matched to the expected spectrum with neutrino oscillation than without. The probability that the observed flux at SK is explained by statistical fluctuation without neutrino oscillation is less than 1%.

Journal Article↗
PubMed2003

Expression of interleukin 6 in synovial tissues in patients with internal derangement of the temporomandibular joint.

Using an immunohistochemical technique, we examined synovial tissue from 46 temporomandibular joints (TMJ) with internal derangement in 44 patients. As controls, we examined synovial tissue specimens from 7 joints with habitual dislocation without pain. In synovial tissues from 21 of the 46 joints with internal derangement, interleukin 6 (IL-6) was expressed in the synovial lining cells and in the mononuclear cells infiltrating the periphery of the blood vessels. The density of IL-6-stained cells in specimens with internal derangement correlated significantly with the grade of joint effusion shown by magnetic resonance imaging (P=0.01, r=0.32).

Adolescent↗
PubMed2003

Correlation and linear regression between blood pressure decreases after a test dose injection of propofol and that following anaesthesia induction.

Propofol reduces systemic vascular resistance and suppresses cardiac function when injected rapidly. In this study we investigated whether blood pressure decrease after a minimal dose (test-dose) injection of propofol correlates with that after an induction-dose injection. Patients were randomly divided into two groups; anaesthesia was induced in group A (n = 60) using 1.5 mg/kg propofol and in group B (n = 61) using 2.0 mg/kg. Blood pressure reduction after a minimal dose injection (0.4 mg/kg) was examined non-invasively prior to anaesthetic induction. Bispectral Index monitoring was measured and sedation level scored to evaluate anaesthetic depth. After the minimal dose injection, 18 of 121 patients showed behaviour suggesting minor disinhibition, five patients were sedated and seven were drowsy. Oxygen saturation was not significantly changed after test-dose injection. Reduction in systolic blood pressure (mean +/- SD) was 17 +/- 11 mmHg after the minimal dose injection, 42 +/- 20 mmHg after a 1.5 mg/kg induction dose injection, and 42 +/- 22 mmHg after a 2.0 mg/kg induction-dose injection. In both groups, blood pressure after induction was significantly lower than the control value (P < 0.05). In both groups, a positive correlation was observed between blood pressure reduction after the minimal dose injection and that after the induction-dose injection [P < 0.01, R value for systolic blood pressure correlation in group A 0.712 (P < 0.01) and in group B 0.758 (P < 0.01)]. We concluded there was a positive correlation between blood pressure reduction after a minimal (test-dose) injection and that after an induction-dose injection.

Adult↗