Adsorption and Elution of Glucuronic Acid and Chondroitin Sulfate Using Amino-Group-Containing Spherical Gel

Abstract: A spherical gel containing amino groups was prepared using monomers of N,N-dimethylacrylamide and N,N-dimethylaminoethyl methacrylate, with a cross-linker composed of N,N′-methylenebisacrylamide prepared by suspension polymerization for the adsorption of glucuronic acid and chondroitin sulfate. The prepared gel was immersed in glucose, glucuronic acid, and chondroitin sulfate solutions to determine the adsorption performance in batch mode, which demonstrated that 20 % of the chondroitin sulfate was adsorbed to the amino-group-containing gel. The amino-group-containing gel was packed into a column to permeate the chondroitin sulfate-containing solution (0.40 g/L) at pH 2.0, and it adsorbed chondroitin sulfate to the gel at a space velocity of 4.5 h^-1. When the space velocity was changed to 1.5 h^-1, the amount of chondroitin sulfate increased. When 0.50 M NaCl solution was permeated through the chondroitin-sulfate-adsorbed gel in column mode, 70 % of the chondroitin sulfate was eluted. This spherical gel may be applicable for acidic glycan recovery using batch and permeation modes.     

YBa2Cu3Ox as an electroconductive catalyst for combustion of carbon monoxide

YBa₂Cu₃O_x, known as a high-Tc superconductor, was used as an electroconductive catalyst and its characteristics in CO oxidation were investigated. Charging 3 V, direct current, heated YBa₂Cu₃O_x up to about 500°C, at which it could catalyze CO oxidation. Thus, this oxide has proper features required for electrically temperature-controlled combustion catalysts: one is self-heating property caused by electric current (Joule's heat) and the other is catalytic activity for combustion. The catalytic activity of YBa₂Cu₃O_x was greatly affected by the oxygen deficiency in the solid which was directly related to the partial pressure of oxygen in the reaction system.     

An expandable time-division circuit switching LSI and networkarchitecture for broadband ISDN

A broadband network architecture is proposed that integrates multimedia services, such as data, video, and telephony information, using 52-Mb/s based STM-paths at the user network interface (UNI). The user can access any new service via the STM-based access network via either synchronous transfer mode (STM) switching or asynchronous transfer mode (ATM) switching. STM circuit switching supports long duration, constant bandwidth data transfer services such as video and high-definition television (HDTV) distribution and will also be used for the crossconnect system. Circuit switching can provide transparent transmission during long connection periods. This paper also proposes an expandable time-division switch architecture, an expandable time-division switching LSI, and an expandable switching module for small to large size system applications. The proposed time-division switching LSI, module, and system handle 52-Mb/s bearer signals and have throughputs of 2.4 Gb/s, 10 Gb/s, and 40 Gb/s, respectively. The time-division switch realizes video distribution with 1:n connections. Finally, a local switching node that features an expandable 52-Mb/s time-division circuit switching network is shown for multimedia access networking     

Analysis of cross-phase modulation (XPM) effect on WDM transmissionperformance

The authors analyse the effect of cross-phase modulation (XPM) on wavelength division multiplexing (WDM) transmissions by experiments and numerical simulations, and provide the XPM limitation in a normalised and closed form formula. They also investigate the effect of XPM on dispersion compensated transmissions. It is shown that the location of dispersion compensators and the amount of compensation should be determined by considering the XPM effect     

Glutathione production by glutathione‐degrading enzymes displayed on proteoliposomes reconstituted from bovine kidney brush border membranes

Glutathione (L ‐γ‐glutamyl‐L ‐cysteinylglycine) is physiologically synthesized through two ATP‐dependent reactions catalyzed by γ‐glutamylcysteine synthase and glutathione synthase. The present study was designed to produce glutathione without the aid of ATP by using glutathione‐degrading enzymes, γ‐glutamyl transpeptidase and aminopeptidase M, in reverse: intrinsically the former enzyme catalyzes the cleavage of glutathione to give L ‐cysteinylglycine and a γ‐glutamyl moiety and the latter hydrolyzes the peptide linkage of L ‐cysteinylglycine. Both enzymes were simultaneously displayed on proteoliposomes, which were reconstituted from bovine kidney brush border membranes by a cholate dialysis method. The kinetic analysis using artificial substrates, L ‐γ‐glutamyl‐p‐nitroanilide for γ‐glutamyl transpeptidase and L ‐leucine‐p‐nitroanilide for aminopeptidase M, revealed that the proteoliposome reconstitution significantly increased the enzyme activities: for both the enzymes the maximum reaction rates were increased and Michaelis constants with the respective substrates were decreased. When the proteoliposomes were incubated with the amino acids glycine, L ‐cysteine, and L ‐glutamate (or L ‐glutamine) at 37 °C, a new product was determined on HPLC analyses using ODS and cation‐exchange columns, coinciding in retention time with authentic glutathione. This product was identified to be glutathione by LC–MS and ¹H‐NMR, after being purified by gel filtration using Sephadex G10 and HSKgel Toyopearl HW‐40F in succession. When the incubation mixture contained acivicin and bestatin, specific inhibitors for γ‐glutamyl transpeptidase and aminopeptidase M, respectively, glutathione was not produced at all. These results indicated that glutathione was produced by two‐step reversible reactions of aminopeptidase M and γ‐glutamyl transpeptidase from its constituent amino acids. The equilibrium glutathione concentration obtained with L ‐glutamine as a glutamyl donor substrate was about 3.5 times higher than that obtained with L ‐glutamate. The maximum pH for the glutathione production was 7.0–7.5, reflecting pH dependence of the activities of the enzymes. Copyright © 2004 Society of Chemical Industry     

Tuning range enhanced by self-phase adjustment in mode-hop-free short-active-region DBR laser

The mode-hop-free tuning range is increased to 6.0 nm by using the self-phase adjustment effect in a short-active-region distributed Bragg reflector laser. The optical power is more than 1 mW for the whole tuning range, and the maximum power is greater than 4 mW. The self-phase adjustment mechanism is also discussed theoretically.     

Induction by interleukin-1 (IL-1) of the mRNA of histidine decarboxylase, the histamine-forming enzyme, in the lung of mice in vivo and the effect of actinomycin D

It is known that the activity of histidine decarboxylase (HDC), the histamine-forming enzyme, is induced in response to various stimuli. However, it has repeatedly been reported that actinomycin D (Act D), a typical inhibitor of RNA synthesis, is either ineffective, or actually potentiates induction of this enzyme. Thus, it has been suggested that the induction of HDC may not require the formation of mRNA, i.e. that pre-formed, long-lived mRNA molecules may be responsible for the induction. In the present study, we examined the effects of interleukin-1alpha (IL-1alpha) on the amount of HDC mRNA present during the induction of HDC activity. In mice injected with IL-1alpha, HDC mRNA increased in the lung, spleen and stomach, but was hardly detectable in these tissues in control (saline-injected) mice. In the lung, the time course of the rise and fall in HDC mRNA was shorter than that of the rise and fall in HDC activity. In the present study, actinomycin D (Act D) did not inhibit the increase in HDC mRNA induced by IL-1alpha; in fact, it potentiated the elevation of both HDC mRNA and HDC activity. These results suggest that IL-1alpha induces HDC activity or its enzyme protein through the formation of short-lived HDC mRNA molecules. This is the first demonstration that Act D can enhance an increase in HDC mRNA: this potentiating, rather than inhibiting, effect is discussed.     

Macro and micro scale modeling of thermal residual stresses in metal matrix composite surface layers by the homogenization method

The modeling of thermal residual stresses generated in TaC/stellite and TiC/stellite composite surface layers produced by the oscillating electron beam remelting on low alloys steel is presented. The homogenization method is applied to analyze the real composite microstructures by utilizing the digital image-based (DIB) geometric modeling technique. Two scales of elastic stress analysis are studied: macroscopic one referring to the global structure of composite layer produced over the substrate of low alloy steel and microscopic, comprising the selected unit cell of composite microstructure. The results of the analysis show the microscopic stress to be few times higher than the macroscopic one with stress level much above the elastic limit of matrix material, which implies the development of plastic field around the inclusions. The ceramic inclusions within the unit cell are found to be under high compressive stresses. Also, the composite surface layer stays in compression, mainly by the influence of the stress component parallel to the layer/substrate interface. The effect of hardphase volume fraction is examined and it is found that for a small volume fractions the macro and micro stress does not differ substantially between composites with TaC and TiC hardphases despite their mismatch in thermophysical properties. Also, the stress modeling is presented for the composite containing other inclusions and the problem of the selection between 2D and 3D model for the stress analysis is discussed. Communicated by S. N. Atluri, 14 August 1996