The Function of Sialidase Revealed by Sialidase Activity Imaging Probe

Sialidase cleaves sialic acid residues from glycans such as glycoproteins and glycolipids. In the brain, desorption of the sialic acid by sialidase is essential for synaptic plasticity, learning and memory and synaptic transmission. BTP3-Neu5Ac has been developed for sensitive imaging of sialidase enzyme activity in mammalian tissues. Sialidase activity in the rat hippocampus detected with BTP3-Neu5Ac increases rapidly by neuronal depolarization. It is presumed that an increased sialidase activity in conjunction with neural excitation is involved in the formation of the neural circuit for memory. Since sialidase inhibits the exocytosis of the excitatory neurotransmitter glutamate, the increased sialidase activity by neural excitation might play a role in the negative feedback mechanism against the glutamate release. Mammalian tissues other than the brain have also been stained with BTP3-Neu5Ac. On the basis of information on the sialidase activity imaging in the pancreas, it was found that sialidase inhibitor can be used as an anti-diabetic drug that can avoid hypoglycemia, a serious side effect of insulin secretagogues. In this review, we discuss the role of sialidase in the brain as well as in the pancreas and skin, as revealed by using a sialidase activity imaging probe. We also present the detection of influenza virus with BTP3-Neu5Ac and modification of BTP3-Neu5Ac.     

Synthesis of thermoresponsive copolymer/silica-coated magnetite nanoparticle composite and its application for heavy metal ion recovery

To enhance chemical stability and suppress of aggregation of magnetite nanoparticles (MNPs), which are used as a support for thermoresponsive copolymer immobilization, silica coating of the MNPs is applied via the electrooxidation method. Although the resulting silica coated-MNPs also formed aggregates, the size distribution of the aggregate shifted to smaller size range. Because of that, the surface area available for copolymer immobilization increased approximately 6.7 times at maximum as compared with that of the uncoated MNPs. It contributed to the increase of the amount of the immobilized copolymer on the silica-coated MNPs, which is approximately four times larger than that on the uncoated MNPs. Fe₃O₄ dissolution test confirmed enhancement of chemical stability of MNPs. The thermoresponsive copolymer immobilized on the silica-coated MNPs shows the ability to recycle Cu(II) ion from Cu(II) containing solution by changing temperature with significantly shorter time than those in other thermoresponsive adsorbents in gel form.     

Anti‐Sway Crane Control Considering Wind Disturbance and Container Mass

A method for estimating the sway angle using an observer has already been proposed. The state observer estimates the sway angle accurately and must use the detected sway angle value. However, the estimated sway angle has an error owing to rope length error, friction force, and wind. Moreover, the container mass cannot be determined, and therefore the observer parameter is not suitable. We already proposed robust antisway control for overcoming rope length error without adding a new sensor. Further, we designed a friction disturbance observer to cancel out the influence of the friction force. In this paper, we first propose a container mass estimation method when a crane system performs rolling up control. The observer parameter can be selected using the estimated mass value. Second, in crane parallel shift control, we propose a robust antisway control even when there is a wind disturbance. We design a wind disturbance observer and propose a wind disturbance estimator to separate the friction observer output from the wind disturbance observer output. We confirm through experiments that the proposed method can reduce vibration.     

Growth of β-FeSi2 layers deposited from a molten salt

β-FeSi₂ layers have been successfully grown using a molten salt method for the first time. It was found that single phase and homogeneous β-FeSi₂ layers with a columnar domain structure can be grown on FeSi substrates. The layer thickness was demonstrated to be controllable by the growth temperature and time, and was diffusion controlled. It was shown that the layers were void- and crack-free compared to similar layers grown on Fe substrates: this difference is explained in terms of Fe diffusion. This vacuum-free simple growth technique is useful for the fabrication of large area semiconductor devices at low cost.     

Lethality of the covalent linkage between mislocalized major outer membrane lipoprotein and the peptidoglycan of Escherichia coli

The major outer membrane lipoprotein (Lpp) of Escherichia coli possesses serine at position 2, which is thought to function as the outer membrane sorting signal, and lysine at the C terminus, through which Lpp covalently associates with peptidoglycan. Arginine (R) is present before the C-terminal lysine in the wild-type Lpp (LppSK). By replacing serine (S) at position 2 with aspartate (D), the putative inner membrane sorting signal, and by deleting lysine (K) at the C terminus, Lpp mutants with a different residue at either position 2 (LppDK) or the C terminus (LppSR) or both (LppDR) were constructed. Expression of LppSR and LppDR little affected the growth of E. coli. In contrast, the number of viable cells immediately decreased when LppDK was expressed. Prolonged expression of LppDK inhibited separation of the inner and outer membranes by sucrose density gradient centrifugation, whereas short-term expression did not. Pulse-labeled LppDK and LppDR were localized in the inner membrane, indicating that the amino acid residue at position 2 functions as a sorting signal for the membrane localization of Lpp. LppDK accumulated in the inner membrane covalently associated with the peptidoglycan and thus prevented the separation of the two membranes. Globomycin, an inhibitor of lipoprotein-specific signal peptidase II, was lethal for E. coli only when Lpp possessed the C-terminal lysine. Taken together, these results indicate that the inner membrane accumulation of Lpp per se is not lethal for E. coli. Instead, a covalent linkage between the inner membrane Lpp having the C-terminal lysine and the peptidoglycan is lethal for E. coli, presumably due to the disruption of the cell surface integrity.     

Human peripheral eosinophils express functional interferon-gamma receptors (IFN-gammaR)

In order to determine whether or not IFN-gammaR is associated with regulatory mechanisms on human eosinophil function, we examined the expression of functional IFN-gammaR on human peripheral eosinophils. In this study, peripheral blood eosinophils were obtained from seven normal controls and 12 patients (bronchial asthma, n = 9, and hypereosinophilic syndrome (HES), n = 3), and the purity of eosinophils was 97.11 +/- 2.31%, n = 19. We first showed that anti-IFN-gammaR alpha-chain MoAb reacted with all tested eosinophils of both normal controls and patients by flow cytometry analysis. We also showed expression of mRNA for the alpha-chain of IFN-gammaR in all purified eosinophils of six individuals. Further, to characterize IFN-gammaR on eosinophils, we did binding experiments with 125I-IFN-gamma on purified peripheral eosinophils. The linear Scatchard plot indicated a single type of high-affinity binding sites (dissociation constant (Kd) = 3.89-4.95 x 10(-10) M, numbers of binding sites = 183-233/cell, n = 3). To determine whether IFN-gammaR on eosinophils is functional, we examined surface eosinophilic cationic protein (ECP) and CD69 induction after IFN-gammaR ligation with recombinant human IFN-gamma (rhIFN-gamma) on eosinophils by flow cytometry. rhIFN-gamma stimulation significantly induced both ECP and CD69 expression on the 2-18 h-cultured eosinophils in a dose-dependent manner. Further, the effects of rhIFN-gamma stimulation were significantly blocked by both a neutralizing anti-IFN-gamma MoAb and a blocking anti-IFN-gammaR MoAb. These results suggest that human peripheral eosinophils express functional IFN-gammaR.     

The heat transfer and pressure drop characteristics of finned tube banks in forced convection (effects of fin height on pressure drop characteristics)

In recent years the requirement for the reduction of energy consumption has been increasing to solve the problems of global warming and the shortage of petroleum resources. For example, in the power generation field, as thermal power generation occupied 60% of the power generation demand, considerable improvement of the thermal efficiency is required. This paper describes the pressure drop characteristics of finned tube banks used for heat exchangers in thermal power generation that were clarified by testing serrated finned tube banks with different fin heights for improved heat transfer and conventional spiral finned tube banks with different fin heights, and an equation to predict pressure drop which is necessary for the heat exchanger design is proposed. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(3): 179–193, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20112     

Heavy arsenic doping of silicon grown by atmospheric pressure selective epitaxial chemical vapor deposition

Selective epitaxial Si with a high arsenic concentration of 2.2×10¹⁹ atoms/cm³ was deposited at a high growth rate of 3.3 nm/min under atmospheric pressure. It was confirmed that this method had excellent selectivity and produced films having good crystalline quality, abrupt dopant profiles at the interfaces, and smooth surfaces. The growth mechanism is discussed in terms of the relationship between the effects of arsenic surface segregation and etching by hydrogen chloride.     

Acidic pH promotes dimerization of Bcl-2 family proteins

Several members of the apoptosis-regulating Bcl-2 family of proteins can homo- or heterodimerize with each other at neutral pH and can also form ion channels in synthetic membranes at low pH. The effects of low pH on dimerization among these proteins, however, have not heretofore been examined. Surface plasmon resonance was used to examine the kinetics of dimerization as a function of pH between the anti-apoptotic protein Bcl-XL (applied in the mobile phase) and three other members of the Bcl-2 family: Bcl-2, Bax, and Bid (immobilized on biosensor chips). In all cases, the relative affinity of dimerization was substantially increased at pH 4.0 compared to pH 7.0-7.4, ranging from a approximately 10-fold enhancement for Bcl-XL/Bcl-XL homodimers to >60-fold for Bcl-XL/Bid heterodimers. Comparison of the apparent association (ka) and dissociation (kd) rates at neutral and acidic pH revealed that the major contributor to increased affinity at low pH was a decreased rate of dimer dissociation. Thus, low pH stabilizes homo- and heterodimeric complexes comprised of Bcl-XL and these other Bcl-2 family proteins. At pH 4.0, the circular dichroism spectra of Bcl-XL and Bax were essentially unchanged relative to pH 7.0-7.4, indicating a complete retention of alpha-helical secondary structure at low pH and excluding gross denaturation of the proteins. Size-exclusion chromatography and bisANS (4,4'-dianilino-1, 1'-binaphthyl-5,5'-disulfonic acid) labeling studies provided indirect evidence that Bcl-XL may undergo conformational changes at low pH. The findings are discussed with respect to the mechanisms of ion-channel formation by Bcl-2 family proteins and the putative molten globule state that has been proposed for these and structurally similar proteins.