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K Itoh

Publications and source records attributed to K Itoh.

At least 19 recordsLinked to original sources
PubMed2007

Sum frequency generation spectroscopic study of the condensation effect of cholesterol on a lipid monolayer.

Sum frequency generation (SFG) spectra and surface pressure-molecular area (pi-A) isotherms have been obtained for mixed cholesterol-DPPC monolayers with cholesterol mole fractions, x(chol.), from 0 to 1.0, at the air-water interface, under same conditions, at 22 degrees C. Analysis of the spectra indicated that incorporation of cholesterol into the monolayers at 3 mN m-1 greatly increases the conformational and orientational order of the alkyl chains of DPPC, maximizing these properties at x(chol.)=0.4. Analysis also indicated that order in the mixed monolayers at 15 and 35 mN m-1 is not affected by incorporation of cholesterol. The pi-A isotherms measured at 3 mN m-1 for the mixed monolayer with x(chol.)=0.4 have the largest negative deviation of the molecular area relative to those of ideal mixtures (the so-called "condensation effect" of cholesterol), indicating the most thermodynamically stable state. Comparison of results from SFG spectra and pi-A isotherms explicitly proved that the condensation effect can be interpreted in terms of conformational and orientational ordering of the alkyl chains of DPPC.

Cholesterol↗
PubMed2007

Expression of APOBEC3G in kidney cells.

The apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G (APOBEC3G), a member of the APOBEC family possessing DNA mutator activity through cytosine deamination, is reported to play an important role in host defense against infections such as those of hepatitis B virus and human immunodeficiency virus. Here, we examined the expression of APOBEC3G in human kidney cells to better understand its biological role against infection. APOBEC3G was immunohistochemically detectable in kidney mesangial cells and also to some extent in kidney epithelial tubular cells. In addition, overexpression of APOBEC3G was shown in renal carcinoma tissues and cell lines. APOBEC3G expression was upregulated by inflammatory cytokines, such as interferon, interleukin-6, and tumor necrosis factor. These results may provide new insight into the role of APOBEC3G in host defense against viral infection and cancer.

APOBEC-3G Deaminase↗
PubMed2006

Spin correlations of strongly interacting massive fermion pairs as a test of Bell's inequality.

We report the results of the first-time test of the local hidden variable theories (Bell-Clauser-Horne-Shimony-Holt) involving strongly interacting pairs of massive spin 1/2 hadrons from the decay of short-lived (tau<10;-21sec) 2He spin-singlet state, populated in the nuclear reaction 2H+;1H-->;2He+n. The novel features of this experiment are (a) the use of an 'event-ready' [corrected] detector of nearly 100% efficiency to prepare an unbiased sample and (b) a focal-plane polarimeter of full 2pi sr acceptance with a random "post selection" of the reference axes. The spin-correlation function is deduced to be S[exp](pi/4)=2.83+/-0.24stat+/-0.07sys. This result is in agreement with nonlocal quantum mechanical prediction and it violates the Bell-CHSH inequality of |S|<or=2 at a confidence level of 99.3%.

Journal Article↗
PubMed2006

Estimating trophic link density from quantitative but incomplete diet data.

The trophic link density and the stability of food webs are thought to be related, but the nature of this relation is controversial. This article introduces a method for estimating the link density from diet tables which do not cover the complete food web and do not resolve all diet items to species level. A simple formula for the error of this estimate is derived. Link density is determined as a function of a threshold diet fraction below which diet items are ignored ("diet partitioning function"). Furthermore, analytic relationships between this threshold-dependent link density and the generality distribution of food webs are established. A preliminary application of the method to field data suggests that empirical results relating link density to diversity might need to be revisited.

Animals↗
PubMed2006

Slow transition of energy transport in high-temperature plasmas.

A new slow transition process for energy transport in magnetically confined plasmas is reported. The slow transition is characterized by the change between two metastable transport conditions characterized by a weak and a strong electron temperature (Te) dependence of normalized heat flux. These two branches are found to merge at the critical gradient. In metastable transport, the derivative of normalized heat flux to the Te gradient, [EQUATION: SEE TEXT], is positive, while it becomes negative during the transition phase. The time for the transition increases as the normalized Te gradient is increased and exceeds the transport time scale characterized by the global energy confinement time.

Journal Article↗
PubMed2006

Food webs: experts consuming families of experts.

Food webs of habitats as diverse as lakes or desert valleys are known to exhibit common "food-web patterns", but the detailed mechanisms generating these structures have remained unclear. By employing a stochastic, dynamical model, we show that many aspects of the structure of predatory food webs can be understood as the traces of an evolutionary history where newly evolving species avoid direct competition with their relatives. The tendency to avoid sharing natural enemies (apparent competition) with related species is considerably weaker. Thus, "experts consuming families of experts" can be identified as the main underlying food-web pattern. We report the results of a systematic, quantitative model validation showing that the model is surprisingly accurate.

Animals↗
PubMed2006

[Emergency small-sized stent placement following aortic true lumen obliteration of Stanford type B acute aortic dissection].

Acute aortic obstruction induced by acute aortic dissection frequently causes life-threatening organ ischemia. Although early reperfusion of lower extremities, renal and mesenteric artery is necessary, surgical treatment such as graft replacement is invasive and may result in myonephropathic-metabolic syndrome (MNMS), which leads to loss of limb and life. We herein report a case of stent placement as a less invasive treatment for true lumen obliteration associated with Stanford type B aortic dissection in a patient with chronic renal failure on hemodialysis. Ten mm metallic stents were placed in the obliterated true lumen of the descending aorta in order to perfuse peripheral organs within 5 hours after occurrence. It relieved symptoms of visceral organ and leg ischemia. On the postoperative day 14, abdominal discomfort after meal, hypertension in the upper extremity and headache appeared. Chest and abdominal computed tomography (CT) revealed stenosis of the true lumen proximal to the stents. On the other hand, the diameter of the true lumen was inversely dilated distal to the stents. Bilateral axillo-femoral artery bypass was performed with relief of upper extremity hypertension and visceral organ ischemia. The patient otherwise had an uneventful course and was discharged on the postoperative day 37. Our experience suggests that emergency stent placement can provide an option that is less invasive, more effective and prompt treatment for patients with visceral organ and leg ischemia resulting from acute aortic dissection.

Aortic Dissection↗
PubMed2006

[Treatment for pinch-off syndrome using a video-assisted thoracoscopic surgery; report of a case].

Use of a central venous catheter (CVC) may be complicated by a catheter fracture, causing an embolism. Pinch-off syndrome is a recognized complication that develops from the use of implantable subclavian venous access devices. Although rare, as it occurs in only 0.8% of the reported cases, the condition can appear as a complication secondary to the insertion of a CVC. We experienced a case of CVC division in a 26-year-old male who had a CVC implanted through the subclavian vein. We failed in our attempt to remove the catheter fragment using video-assisted thoracoscopic surgery (VATS). If no complication occur over a long-term, it is highly possible that the catheter fragment will become adhered to the vessel wall. Therefore, it may not be necessary to remove the fragment in those cases.

Adult↗
PubMed2005

Propionibacterium freudenreichii component 1.4-dihydroxy-2-naphthoic acid (DHNA) attenuates dextran sodium sulphate induced colitis by modulation of bacterial flora and lymphocyte homing.

BACKGROUND AND AIMS: 1.4-Dihydroxy-2-naphthoic acid (DHNA), a bifidogenic growth stimulator from Propionibacterium freudenreichii, is thought to have a beneficial effect as a prebiotic; however, its in vivo effect on intestinal inflammation remains unknown. The aim of this study was to determine whether oral administration of DHNA can ameliorate dextran sodium sulphate (DSS) induced colitis and to determine the possible underlying mechanisms. METHOD: Colitis was induced in mice by treatment with 2.0% DSS for seven days. DHNA (0.6 or 2.0 mg/kg) was given in drinking water prior to (preventive study) or after (therapeutic study) DSS administration. Colonic damage was histologically scored, and mucosal addressin cell adhesion molecule 1 (MAdCAM-1) expression and beta7 positive cell infiltration were determined by immunohistochemistry. mRNA levels of proinflammatory cytokines (interleukin (IL)-1beta, IL-6 and tumour necrosis factor alpha (TNF-alpha)) were determined by quantitative real time polymerase chain reaction. In addition, bacterial flora in the caecum, concentrations of short chain acids, and luminal pH were examined. RESULTS: DHNA improved survival rate and histological damage score in mice administered DSS in both the preventive and therapeutic studies. DHNA significantly attenuated the enhanced expression of MAdCAM-1, the increased beta7 positive cell number, and the increased mRNA levels of IL-1beta, IL-6, and TNF-alpha in DSS treated colon. In addition, the decreased number of Lactobacillus and Enterobacteriaceae induced by DSS was recovered by DHNA. Preventive effects on decrease in butyrate concentration and decrease in pH level in mice administered DSS were also observed in the DHNA preventive study. CONCLUSION: DHNA, a novel type of prebiotic, attenuates colonic inflammation not only by balancing intestinal bacterial flora but also by suppressing lymphocyte infiltration through reduction of MAdCAM-1.

Animals↗
PubMed2005

Resolving the discrepancy of 135 MeV pd elastic scattering cross sections and relativistic effects.

Three precise measurements for elastic pd scattering at 135 MeV/A have been performed with the three different experimental setups. The cross sections are described well by the theoretical predictions based on modern nucleon-nucleon forces combined with three-nucleon forces. Relativistic Faddeev calculations show that relativistic effects are restricted to backward angles. This result supports the two measurements recently reported by RIKEN and contradicts the KVI data.

Journal Article↗
PubMed2005

UFT plus gemcitabine combination chemotherapy in patients with advanced non-small-cell lung cancer: a multi-institutional phase II trial.

A multi-institutional phase II trial was conducted to evaluate the efficacy and toxicity of combination chemotherapy consisting of gemcitabine and UFT, which is composed of tegafur and uracil, for non-small-cell lung cancer (NSCLC) patients. Patients with advanced NSCLC received an oral administration of UFT (tegafur 200 mg m(-2)) b.i.d. from days 1 to 14 and intravenous injection of gemcitabine 900 mg m(-2) on days 8 and 15. This treatment was repeated every 4 weeks. A total of 44 patients were enrolled into this trial. The median age of all patients was 74 years, with 23 patients younger than 75 years and 21 patients with 75 years of age or older. A total of 18 patients (41%) achieved a partial response. The median survival time was 13.2 months and the 1-year survival rate was 59%. The most common grade 3-4 toxicity was neutropenia (57%). The frequency of grade 3 nonhaematologic toxicities was less than 5%. In addition, no significant difference in the response, survival or toxicities was observed between the patients younger than and those older than 75 years of age. This combination chemotherapy demonstrated a promising effectiveness and acceptable toxicity in patients with advanced NSCLC, even in patients older than 75 years. .

Aged↗
PubMed2005

Some properties of the speciation model for food-web structure-mechanisms for degree distributions and intervality.

We present a mathematical analysis of the speciation model for food-web structure, which had in previous work been shown to yield a good description of empirical data of food-web topology. The degree distributions of the network are derived. Properties of the speciation model are compared to those of other models that successfully describe empirical data. It is argued that the speciation model unifies the underlying ideas of previous theories. In particular, it offers a mechanistic explanation for the success of the niche model of Williams and Martinez and the frequent observation of intervality in empirical food webs.

Animals↗
PubMed2005

Study of B0-->rho+/- pi-/+ time-dependent CP violation at Belle.

We present a time-dependent analysis of CP violation in B0-->rho(+/-)pi(-/+) decays based on a 140 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at KEKB. We obtain the charge asymmetry A(rhopi)(CP)=-0.16+/-0.10(stat)+/-0.02(syst). An unbinned maximum-likelihood fit to the Deltat distributions yields C(rhopi)=0.25+/-0.17(stat)+0.02-0.06(syst), DeltaC(rhopi)=0.38+/-0.18(stat)+0.02-0.04(syst), S(rhopi)=-0.28+/-0.23(stat)+0.10-0.08(syst), and DeltaS(rhopi)=-0.30+/-0.24(stat)+/-0.09(syst). The direct CP violation parameters for B-->rho(+)pi(-) and B-->rho(-)pi(+) decays are A(+-)(rhopi)=-0.02+/-0.16(stat)+0.05-0.02(syst) and A(-+)(rhopi)=-0.53+/-0.29(stat)+0.09-0.04(syst).

Journal Article↗
PubMed2005

Raman microspectroscopic study on polymerization and degradation processes of a diacetylene derivative at surface enhanced Raman scattering active substrates. 1. Reaction kinetics.

Raman microspectroscopy was applied to study the polymerization kinetics of the Langmuir-Blodgett (LB) films of 10,12-pentacosadiynoic acid (DA) adsorbed on surface enhanced Raman scattering (SERS) active Ag island films. A two-dimensional (2D) Raman microscopic image measured at 1520 cm(-1) exhibits bright and dim spots with the diameter of several hundred nanometers. Raman microscopic spectra, measured by defocusing the excitation laser light (532 nm, diameter of ca. 10 mum) on the samples at room temperature, proved the occurrence of the surface processes consisting of the formation of polydiacetylene (PDA) in the blue phase, its conversion to the red phase, and subsequent bleaching. These reactions were negligible under the same condition for the DA-LB films prepared on a smooth (i.e., SERS-inactive) Ag film, indicating that the 532-nm-induced polymerization and the bleaching process are enhanced by the SERS-active substrates. At low temperatures below -50 degrees C, the Raman microscopic measurements proved the formation of the blue phase and its conversion to the red phase with much lower reaction rates compared to the corresponding rates at room temperature. The bleaching, however, was much suppressed at the low temperatures. The kinetic analyses of the formation of the blue phase and its conversion to the red phase were performed by using the intensity changes of the Raman bands due to the blue (1477 cm(-1)) and red (1517 cm(-1)) phases as a function of the irradiation time. The results strongly suggested the existence of at least two processes taking place simultaneously on the SERS-active substrates; that is, one of the processes is a sequential reaction, DA-monomers --> PDA in the blue phase --> PDA in the red phase, and the other is another sequential reaction, DA-monomers --> PDA in the red phase --> degradation species (probably amorphous carbon). Thus, even at the low temperatures, there occurs the surface reaction consisting of the formation of PDA and its degradation. The reaction can be ascribed to a process taking place at the highly SERS-active site, which gives the bright spot (so-called "hot spot") on the 2D Raman image, as proved by the confocal Raman microscopic measurement in the following paper.

Adsorption↗
PubMed2005

Raman microspectroscopic study on polymerization and degradation processes of a diacetylene derivative at surface enhanced Raman scattering active substrates. 2. Confocal Raman microscopic observation of polydiacetylene adsorbed on active sites.

Confocal Raman microscopic measurements were performed at room temperature on the Langmuir-Blodgett (LB) monolayer of 10,12-pentacosadiynoic acid (DA) prepared on surface enhanced Raman scattering (SERS) active Ag island films, two-dimensional (2D) Raman images of which exhibit bright and dim spots on a dark background. The measurements performed by focusing the excitation laser light (488 nm) on the dark background indicate the prompt appearance of the Raman bands (1515 and 2115 cm(-1)) due to polydiacetylene (PDA) in the red phase and subsequent diminution of the Raman bands. On the other hand, the spectra observed by focusing the excitation laser spot on the dim and bright spots exhibit almost random fluctuations, giving rather narrow Raman bands in the 1620-1000 cm(-1) region, which appear and disappear temporarily with varying intensities under the continuous irradiation at 488 nm. Broad Raman bands appear around 1580 and 1360 cm(-1), which are ascribable to amorphous carbon, at a later stage of the observation, the intensities from the bright spot being more than 100 times stronger than those from the dim spot. The narrow bands are ascribed to a series of carbonaceous intermediates such as polyenes, graphite sheets with various sizes, and folded or reorganized forms of the sheets including carbon nanotubes and fullerenes, which are formed during the conversion of PDA to amorphous carbon. The random spectral fluctuation was interpreted by considering that the intermediates undergo thermally activated diffusion and get temporarily in contact with the SERS-active site, resulting in the enhancement of their Raman bands and the fluctuation.

Adsorption↗
PubMed2005

A new three-dimensional automatic bodymarker system for transvaginal ultrasonography.

OBJECTIVE: To evaluate the accuracy and usefulness of a newly developed three-dimensional automatic bodymarker system for transvaginal ultrasonography. METHODS: A bodymarker system which utilizes an electromagnetic field to specify the probe position was developed. Software was written which enabled the positional information of the probe and the ultrasound image to be simultaneously displayed on a personal computer. The bodymarker was displayed as a three-dimensional graphic model. The differences between the estimated and the actual position--i.e. the error--for both position (x, y and z) and angles (azimuth, elevation and roll) of the probe were measured. The movement of the probe was then evaluated in healthy female volunteers and the comparative time required for ultrasound examination was determined. RESULTS: Both the position and the angles of the probe were accurately shown in the computer display. The errors were 1.0 mm and 0.7 degrees (median) for position and angle, respectively. The system was also shown to work well in healthy female volunteers. Calibration of the new system required only 5.0 seconds, compared with an average of 7.6 seconds for the conventional bodymarker. CONCLUSION: The newly developed three-dimensional automatic transvaginal bodymarker system provides an accurate indication of probe position and its tilting angle. It works well in healthy female volunteers and speeds up the examination time. It may be clinically useful for transvaginal ultrasound examination.

Calibration↗