Extracellular adenosine 5'-triphosphate induces Ca2+ efflux from freshly isolated adult rat cardiomyocytes: possible involvement of Na+/Ca2+ exchange mechanism

In the present study, we examined the effect of extracellular adenosine 5'-triphosphate (ATP) on Ca2+ efflux from freshly isolated adult rat cardiomyocytes. ATP at 1 mM caused a release of 3.6+/-0.08% of the total cellular content. The 45Ca2+ efflux from the cells was also stimulated by adenosine-5'-O-(3-thiotriphosphate) (ATP-gamma s), alpha, beta-methylene-ATP and adenosine 5'-diphosphate (ADP), but not by adenosine 5'-monophosphate (AMP) or adenosine. The effect of ATP was inhibited by a known purinergic P2-receptor antagonist, but not by a P1-receptor antagonist. From these results, it is conceivable that the effect of ATP on Ca2+ efflux from cardiomyocytes is mediated through P2-purinoceptors. It was also observed that ATP caused a rise in [Ca2+]i to almost 200 nM. The ATP-stimulated 45Ca2+ efflux was not affected by removal of extracellular Ca2+, but was dependent on the presence of extracellular Na+. Moreover, ATP caused a 22Na+ influx into the cells of about 2.0-fold over the basal value. These result suggest that ATP stimulates extracellular Na+-dependent 45Ca2+ efflux from freshly isolated adult rat cardiomyocytes, probably through its stimulatory effect on plasma membrane P2-purinoceptors which may couple to Na+/Ca2+ exchange.     

Robust design of body slip angle observer for electric vehicles and its experimental demonstration

Electric vehicles (EVs) are inherently suitable for two‐dimensional vehicle motion control. To utilize EV's advantages, body slip angle β and yaw rate γ play an important role. However, as sensors to measure β are very expensive, we need to estimate β from only variables to be measurable. In this paper, an improved estimation method for body slip angle β for EVs is proposed. This method is based on a linear observer using side acceleration ay as well as γ information. We especially considered the design of gain matrix and succeeded in exact and robust estimation. We performed experiments by UOT March II. This experimental vehicle driven by four in‐wheel motors was made for research on advanced control of EVs. Some experimental results are shown to verify the effectiveness of the proposed method. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(1): 80–86, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20339     

External-cavity semiconductor laser with focusing grating mirror

A novel external-cavity semiconductor laser with a focusing grating mirror (FGM), which enables a single-mode oscillation at a specified wavelength, is proposed. The optical properties of the FGM, which is a computer-generated holographic grating with chirp and bend structure, are numerically analyzed. An optimally designed FGM for realizing laser oscillation at a specific wavelength of 1.30 μm is fabricated by using a computer-controlled electron-beam writing system. The fabricated FGM with grating area of 1×1 mm² is combined as an external feedback mirror with an InGaAsP-InP semiconductor laser of 1.3 μm wavelength range, and the lasing characteristics are experimentally measured. Stable and single-mode oscillations with spectral line width less than 10 MHz are observed     

On the unstable propagation of a phase transition in a solid

To explore a possible mechanism of deep earthquakes, this paper analyzes the unstable propagation of a stress-induced phase transition which is initiated in a homogeneous stress field. This Stephen problem is formulated as an initial-value problem for the phase boundary, and the driving force of the boundary is computed by using the solution of the boundary-value problem for a partially transformed material. The propagation of the phase transition under uniform pressure is numerically simulated. It is shown that (1) under lower pressure, the transition is terminated at a certain size, but it can propagate unstably when an initially transformed region is sufficiently large; and (2) when the pressure attains a critical value, the propagation becomes unstable, and goes in a particular direction depending on the initial shape. These results confirm the possibility of the unstable propagation of phase transition, and provide a theoretical basis for the hypothesis that the phase transition of a mantle material can trigger a deep earthquake.     

Differential cell- and immuno-biological properties of murine B16-F1 and F10 melanomas: oncogene c-fos expression, sensitivity to LAK cells and/or IL-2, and components of gangliosides

Differential cell- and immuno-biological properties of two murine melanoma B16 variants, B16-F1 and F10, were investigated. Studies focused on the expression of proto-oncogene c-fos, sensitivities to LAK cells and/or IL-2, and modulation of the expression of ganglioside components after treatment with IL-2. Proto-oncogene c-fos was found to be highly expressed in F10 lines by an in situ hybridization technique and also in F10 lung metastatic nests by immunofluorescent staining with anti-c-fos antibody. F1 melanomas were more sensitive to local injection of IL-2. F10 melanomas hardly responded to IL-2 treatment, but successive injections of a combination of LAK cells and IL-2 did cause prolongation of survival rates, even of F10 melanoma-burdened mice. A major component of gangliosides of both F1 and F10 melanomas was GM3. Production of GM3 in F10 melanomas treated with IL-2 for 4 days increased, and, if the treatment was continued for 7 days, minor components of gangliosides, such as GM2, GM1, and GD1a, appeared only in F1 melanomas, while the increase of production of GM3 disappeared in both melanomas. These experimental results may provide clues for additional mechanisms which allow these two murine melanoma variants to show different implantation and metastasis rates.     

Dynamic driving/braking force distribution in electric vehicles with independently driven four wheels

A novel algorithm for the dynamic driving/braking force distribution is proposed for electric vehicles (EV) with four in‐wheel motors. In such EVs, the vehicle lateral motion can be controlled by a yaw moment, generated by the torque difference between wheels. This method is known as DYC (Direct Yaw moment Control) in ordinary engine vehicle engineering; however, the torque difference can be generated more directly with in‐wheel motors. One problem of DYC is its instability on slippery roads, such as wet or snowy asphalt. To achieve high stability, the loads of wheels are preferably equal. The load on each wheel can be evaluated as the square root of the sum of squares of driving/braking force and side force. Therefore, the driving/braking forces, or motor torques, should be distributed depending on the side forces of the wheels, to minimize the load imbalance between wheels. The proposed algorithm can solve this optimization problem approximately with little calculation cost, and thus this method can be applied for real‐time calculation within a control period. Approximate solutions obtained with the proposed method are evaluated by comparison with numerical solutions that require much calculation time. The difference between these solutions is shown to be negligible, indicating the effectiveness of the proposed method. © 2001 Scripta Technica, Electr Eng Jpn, 138(1): 79–89, 2002     

Prism-pair interferometry by homodyne interferometers with a common light source for high-accuracy measurement of the absolute refractive index of glasses

A prism-pair interferometer comprising two homodyne interferometers with a common light source was developed for high-precision measurements of the refractive index of optical glasses with an uncertainty of the order of 10(-6). The two interferometers measure changes in the optical path length in the glass sample and in air, respectively. Uncertainties in the absolute wavelength of the common light source are cancelled out by calculating a ratio between the results from the interferometers. Uncertainties in phase measurement are suppressed by a quadrature detection system. The combined standard uncertainty of the developed system is evaluated as 1.1×10(-6).     

Effects of photoirradiation in UV and VUV regions during plasma exposure to polymers

Interactions between photons irradiated from Ar-O₂ mixture plasmas and polymer surfaces were investigated on the basis of depth analyses of chemical bonding states in the nano-surface layer of polyethylene terephthalate (PET) films via hard X-ray photoelectron spectroscopy (HXPES) and conventional X-ray photoelectron spectroscopy (XPS). The PET films were exposed to photons from the Ar-O₂ mixture plasmas by covering the PET samples with MgF₂ and quartz windows as optical filters for evaluation of photoirradiation effects in ultraviolet (UV) and vacuum ultraviolet (VUV) regions. The HXPES results indicated that the degradation of the chemical bonding states due to photoirradiation in regions was insignificant in deeper regions up to about 50 nm from the surface. Whereas, conventional XPS analysis showed that CO bond, OCO bond and CO bond increased after photoirradiation in UV and VUV regions. These results suggest that the increase in oxygen functionalities (CO bond, OCO bond and CO bond) may be attributed to chemical reactions and/or terminations of scissed bonds via photodecompositions of the polymer with oxygen and/or OH species (oxygen molecules and radicals during plasma exposure and/or oxygen molecules and moisture after taking the PET samples out of the plasma reactor to the ambient air) in the vicinity of the sample surface.     

Model Test and Consolidation Analysis of Failure of a Loose Sandy Embankment Dam During Seepage

Failures of earth dam embankments and river dikes, which are constructed of sandy soils with low dry densities, have been observed to occur during rising of water levels. In this paper, a large-scale physical model test was conducted in order to investigate the behavior of a small dam embankment as water levels rose. The test results were simulated by use of a consolidation analysis method coupled with an elastoplastic model for unsaturated soils. All parameters used in the simulation were obtained from element tests; oedometer, triaxial compression, soil water retention, and permeability tests. First, in order to verify the parameters identified, direct shear tests were simulated using the consolidation analysis method; results of the simulation and the tests were consistent. From the embankment model test it was found that the crest of the embankment moved upstream at the first stage of impounding and then moved back. After a seepage surface appeared on the downstream slope, tension cracks occurred on the downstream slope, and sliding occurred through the crack and the downstream toe. The results of the simulation were consistent with those of the model test. This consolidation analysis method could be used to simulate the complex deformations induced by saturation collapse and shear strains and even failure behavior. Old embankments constructed with loose densities might have histories in which cracks occurred on the downstream slopes when the reservoir water level rose, and their stabilities might have decreased.     

Inhibitory effect of zinc on beta-hexosaminidase release from RBL-2H3 cells by synthetic chemicals

The effects of foods and chemicals related to food hygiene on degranulation were evaluated using a method for assaying the enzyme activity of beta-hexosaminidase as an index of chemical mediator release from RBL-2H3 cells in vitro. Using a previously developed assay system, we had found a large number of inhibitors and promoters of degranulation of RBL-2H3 cells. In the present study, we examined the inhibitory effect of zinc chloride on the degranulation (beta-hexosaminidase release) from RBL-2H3 cells with or without antigen in the presence of the degranulation-promotive chemicals, namely, 4 food additives, 7 pesticides and 2 veterinary drugs. These promotive chemicals were classified into two types on the basis of inhibitory profile by zinc chloride: 1) those which showed marked degranulation-inhibitory action when the cells were stimulated with antigen, such as butylhydroxyanisole, dibutylhydroxytoluene, EPN, cis- and trans-permethrin, prothiofos, pyridaben, terbufos, 2) those which showed marked degranulation-inhibitory action whether the cells were stimulated with antigen or not, such as butyl p-hydroxybenzoate, o-phenylphenol, bitertanol, salinomycin. In conclusion, zinc had a dramatic inhibitory effect on enhanced degranulation induced by synthetic chemicals in vitro.