Ca2+-ATPase Molecules as a Calcium-Sensitive Membrane-Endoskeleton of Sarcoplasmic Reticulum

The Ca²⁺-transport ATPase of sarcoplasmic reticulum (SR) is an integral, transmembrane protein. It sequesters cytoplasmic calcium ions released from SR during muscle contraction, and causes muscle relaxation. Based on negative staining and transmission electron microscopy of SR vesicles isolated from rabbit skeletal muscle, we propose that the ATPase molecules might also be a calcium-sensitive membrane-endoskeleton. Under conditions when the ATPase molecules scarcely transport Ca²⁺, i.e., in the presence of ATP and ≤ 0.9 nM Ca²⁺, some of the ATPase particles on the SR vesicle surface gathered to form tetramers. The tetramers crystallized into a cylindrical helical array in some vesicles and probably resulted in the elongated protrusion that extended from some round SRs. As the Ca²⁺ concentration increased to 0.2 µM, i.e., under conditions when the transporter molecules fully carry out their activities, the ATPase crystal arrays disappeared, but the SR protrusions remained. In the absence of ATP, almost all of the SR vesicles were round and no crystal arrays were evident, independent of the calcium concentration. This suggests that ATP induced crystallization at low Ca²⁺ concentrations. From the observed morphological changes, the role of the proposed ATPase membrane-endoskeleton is discussed in the context of calcium regulation during muscle contraction.     

采用Ni—Cr合金热喷涂延长连铸结晶器寿命

三岛光产所开发的Ni-Cr合金热喷涂结晶器,是通过对连铸结晶器表面喷涂Ni-Cr合金涂层,使其寿命达到原来镀Ni结晶器的3-6倍,本文介绍Ni-Cr合金热喷涂结晶器的特性、使用效果和使用上的注意点。     

Efficient Photocatalytic Decomposition of Glucose,Starch, and Cellulose to CO<Subscript>2</Subscript> Using a Mesoporous Semiconductor Thin Film

Abstract  

UV light-activated highly efficient photocatalytic decomposition of aqueous glucose and polysaccharides (starch and cellulose) to CO₂ was successfully achieved by using a mesoporous TiO₂ thin film coated on a fluorine-doped transparent conductive glass (FTO). The external quantum efficiency (η) of 0.08 (=8%) was obtained for glucose photodecomposition at neutral pH based on the total incident UV light, and the internal quantum efficiency (η′) was 8 (=800%) based on the photon that was effective for activating the reactant, demonstrating that the major decomposition mechanism is dark auto-oxidation of the activated reactant by O₂. Glucose gave η′ values of 19 at pH 12 and 25 at pH 2 demonstrating that when a glucose molecule was once activated by one photon, the molecule can undergo auto-oxidative decomposition to CO₂ at these pH under dark. Water-soluble starch was also photodecomposed completely to CO₂ with estimated η′ value of 8.6. Water-soluble carboxymethyl cellulose (CMC) also underwent decomposition to CO₂ with similar efficiency of η′ = 5. Solid state cellulose powders could be photodecomposed to CO₂ by sandwiching them between FTO-coated TiO₂ thin films.     

Second-order adjoint equation method for parameter identification of rock based on blast waves in tunnel excavation

The objective of this study is to present a method for identifying the elastic moduli of ground rock via the first- and second-order adjoint methods using blast vibration measurements during tunnel excavation. For identifying these parameters, the magnitudes of the blast force should be identified beforehand. Parameter identification is a minimization problem of the square sum of the discrepancy between the computed and observed velocities. The magnitudes of the three components of borehole pressure are assumed to be independent in each direction. The propagation of an elastic wave is assumed because the amplitude of such a wave is infinitesimal. The three-dimensional finite element method and the linear acceleration method are used effectively. The extended performance function can be expanded into a series of small constants to derive the necessary condition of minimization. The adjoint equation and the dynamic equation of motion can be used to obtain the gradient and the Hessian product of the extended performance function with respect to the parameters. The weighted gradient method and Broyden–Flecher–Goldfarb–Shanno method are successfully employed for the minimization. By applying the present identification technique at the Ohyorogi tunnel site, the fact that the computed and observed velocities are well in agreement is verified. The present method can be shown to be useful for tunnel excavation.     

Clinical significance of the urinary oxygen tension in patients with ischemic heart disease

The clinical significance of the urinary oxygen tension (PuO2) was evaluated in 60 patients with ischemic heart disease. The PuO2 had fair relations to cardiac index and serum creatinine level (r = 0.73 and r = 0.73, respectively). Although the PuO2 had a fair relation to serum creatinine in patients with a low cardiac index, there was no relation to the cardiac index. In patients with increases in PuO2 from day 1 to day 2, the cardiac index increased, and the serum creatinine level decreased on the 2nd day, whereas a sustained decrease in cardiac index and an increase in serum creatinine were observed in patients with a decrease in PuO2 from day 1 to day 2. Thus, PuO2 can be used as an indicator of the renal function in patients with ischemic heart disease.     

Natural convection heat transfer from horizontal rod bundles in liquid sodium. Part 2: Correlations for horizontal rod bundles based on theoretical results

Natural convection heat transfer from horizontal rod bundles in N_xm × N_ym arrays (N_xm, N_ym = 5–9) in liquid sodium was numerically analyzed for three types of the bundle geometry (in-line rows, staggered rows I and II). The unsteady laminar two-dimensional basic equations for natural convection heat transfer caused by a step heat flux were numerically solved until the solution reaches a steady state. The PHOENICS code was used for the calculation considering the temperature dependence of thermophysical properties concerned. The surface heat fluxes for each cylinder were equally given for a modified Rayleigh number, R_f, ranging from 0.0637 to 63.1 (q = 1×10⁴ to 7×10⁶ W/m²). S_x/D and S_y/D for the rod bundle, which are the ratios of the distance between center axes on the abscissa and the ordinate to the rod diameter, respectively, were ranged from 1.6 to 2.5 on each bundle geometry. The spatial distribution of Nusselt numbers, Nu, on horizontal rods of a bundle was clarified. The average value of Nusselt number, Nu_av, for three types of bundle geometry with various values of S_x/D and S_y/D were calculated to examine the effect of the array size, S/D and R_f on heat transfer. The bundle geometry for the higher Nu_av value under the condition of S_x/D×S_y/D = 4 was examined by changing the ratio of S_x/S_y. A correlation for Nu_av for the three types of bundle geometry above mentioned including the effects of S_x/D and S_y/D was developed. The correlation can describe the theoretical values of Nu_av for the three types of bundle geometry in N_xm × N_ym arrays (N_xm, N_ym = 5–9) for S_x/D and S_y/D ranging from 1.6 to 2.5 within 10% difference.     

Tumor-Suppressor Role of the α1-Na/K-ATPase Signalosome in NASH Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality worldwide, with an estimate of 0.84 million cases every year. In Western countries, because of the obesity epidemic, non-alcoholic steatohepatitis (NASH) has become the major cause of HCC. Intriguingly, the molecular mechanisms underlying tumorigenesis of HCC from NASH are largely unknown. We hypothesized that the growing uncoupled metabolism during NASH progression to HCC, manifested by lower cell redox status and an apoptotic ‘switch’ activity, follows a dysregulation of α1-Na/K-ATPase (NKA)/Src signalosome. Our results suggested that in NASH-related malignancy, α1-NKA signaling causes upregulation of the anti-apoptotic protein survivin and downregulation of the pro-apoptotic protein Smac/DIABLO via the activation of the PI3K → Akt pro-survival pathway with concomitant inhibition of the FoxO3 circuit, favoring cell division and primary liver carcinogenesis. Signalosome normalization using an inhibitory peptide resets apoptotic activity in malignant cells, with a significant decrease in tumor burden in vivo. Therefore, α1-NKA signalosome exercises in HCC the characteristic of a tumor suppressor, suggesting α1-NKA as a putative target for clinical therapy.     

Evaluation of the Effects of Microgravity on Activated Primary Human Hepatic Stellate Cells

In recent years, research has been conducted to develop new medical treatments by simulating environments existing in space, such as zero-gravity. In this study, we evaluated the cell proliferation and gene expression of activated primary human hepatic stellate cells (HHSteCs) under simulated microgravity (SMG). Under SMG, cell proliferation was slower than in 1 G, and the evaluation of gene expression changes on day 1 of SMG by serial analysis of gene expression revealed the presence of Sirtuin, EIF2 signaling, hippo signaling, and epithelial adherence junction signaling. Moreover, reactive oxygen species were upregulated under SMG, and when N-acetyl-cystein was added, no difference in proliferation between SMG and 1 G was observed, suggesting that the oxidative stress generated by mitochondrial dysfunction caused a decrease in proliferation. Upstream regulators such as smad3, NFkB, and FN were activated, and cell-permeable inhibitors such as Ly294002 and U0126 were inhibited. Immunohistochemistry performed to evaluate cytoskeletal changes showed that more β-actin was localized in the cortical layer under SMG.     

Developing a stereoscopic CG system with motion parallax and interactive digital contents on the system for science museums

Multimedia Tools and Applications - As we watch 3D objects and move around them, the appearance of the objects would change. This is called motion parallax and it is one of important depth cues. We...     

Metastable-Stable Phase Transformation Behavior of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Scale Formed on Fe–Ni–Al Alloys

The oxidation behavior of Ni–Fe–41.5at.%Al alloys with different Fe/Ni ratios was investigated in air at 1000 °C in order to clarify the effect of Fe on the phase transformation of Al₂O₃ scale, using in-situ high-temperature X-ray diffraction by means of synchrotron radiation. The oxidation mass gain of alloys after 25 h of oxidation generally decreased with increasing Fe content; however, the initial oxidation mass gain was significantly decreased by increasing alloy Fe content. In-situ X-ray diffraction analysis indicated that higher alloy Fe contents promoted rapid formation of the stable α-Al₂O₃, while lower Fe in the alloy maintained the metastable Al₂O₃ for longer time oxidation. The effect of Fe on promoting α-Al₂O₃ formation can be explained by the initial formation of α-Fe₂O₃, whose structure is isomorphous with α-Al₂O₃. The additional effect of Fe on the growth rate of α-Al₂O₃ is also discussed.