Effect of Ganglioside GM3 Synthase Gene Knockout on the Glycoprotein N‐Glycan Profile of Mouse Embryonic Fibroblast

The structural and clinical significance of cellular glycoproteins and glycosphingolipids (GSLs) are often separately discussed. Considering the biosynthetic pathway of glycoconjugates, glycans of cell‐surface glycoproteins and GSLs might partially share functions in maintaining cellular homeostatis. The purpose of this study is to establish a general and comprehensive glycomics protocol for cellular GSLs and N‐glycans of glycoproteins. To test the feasibility of a glycoblotting‐based protocol, whole glycans released both from GSLs and glycoproteins were profiled concurrently by using GM3 synthase‐deficient mouse embryonic fibroblast GM3(?/?). GM3(?/?) cells did not synthesize GM3 or any downstream product of GM3 synthase. Instead, expression levels of o‐series gangliosides involving GM1‐b and GD1‐α increased dramatically, whereas a‐/b‐series gangliosides were predominantly detected in wild‐type (WT) cells. We also discovered that glycoprotein N‐glycan profiles of GM3(?/?) cells are significantly altered as compared to WT cells, although GM3 synthase is responsible only for GSLs synthesis and is not associated with glycoprotein N‐glycan biosynthesis. The present approach allows for high‐throughput profiling of cellular glycomes enriched by different classes of glycoconjugates, and our results demonstrated that gene knockout of the enzymes responsible for GSL biosynthesis significantly influences the N‐glycans of glycoproteins.     

Electron Cyclotron Resonance Plasma-Enhanced Metalorganic Chemical Vapor Deposition of Tantalum Oxide Thin Films on Silicon near Room Temperature

Films of tantalum oxide, ranging in thickness from 25 to 2000 nm, were successfully deposited on silicon by the electron cyclotron resonance plasma-enhanced metalorganic chemical vapor deposition (ECR-MOCVD) process at deposition rates of up to 33 nm/min. The films were produced by decomposition of tantalum pentaethoxide into tantalum oxide in an oxygen ECR microwave plasma. The films were amorphous (but fully dense) since the temperature of the substrate, which was unheated, was estimated to be 76–120°C. The growth of the tantalum oxide films was accompanied by the formation of an interlayer of silicon dioxide at the silicon interface. The tantalum oxide films were oxygen rich (relative to Ta₂O₅). The effective relative dielectric constant of these dual-layer dielectrics ranged from ɛ_ef= 8.5 to 24; this range was explained in terms of a bilayer consisting of a 13-nm-thick silicon dioxide layer of ɛ_sx= 4, and a tantalum oxide overgrowth of varying thickness having ɛ_tx∼ 25. A maximum breakdown strength of the films was 6.9 MV/cm and the leakage current at a field of 1 MV/cm was 3.0 × 10^-8. The breakdown properties were related to the presence of stray particles on the substrate; these properties are expected to improve considerably if the processing is carried out in a clean-room environment. The silicon dioxide layer is believed to have grown by the diffusion of oxygen through the tantalum oxide overlayer despite the low substrate temperature.     

Single‐Jet Precipitation of Silver Nanocrystals in the Presence of Poly(acrylic) Acid

Precipitation of silver nanocrystals was carried out in a poly(acrylic) acid (PAA) solution by using a single‐jet crystallizer. The influence of the feeding rate, the injection position and the PAA dosage on the crystal size distribution (CSD) was clarified. The precipitated silver nanocrystals agglomerate with each other, forming an agglomerated microcrystal. In the presented case, smaller feeding rates caused smaller crystal sizes and narrower CSD widths. PAA, which is a water‐soluble polyelectrolyte, successfully inhibited agglomeration and crystal growth, and decreased the crystal size and the CSD width. Thus, this idea may also facilitate the production of other nano‐/microcrystalline particles.     

Microwave tissue coagulation therapy compared to hepatectomy for whole-liver multinodular hepatocellular carcinoma

We compared the effectiveness of microwave tissue coagulation therapy (MTC) with the effectiveness of hepatectomy for patients with whole-liver multinodular hepatocellular carcinoma (HCC). The comparison was made using two sub-groups of 67 patients treated for multinodular HCC in the whole liver. One subgroup (group M, 17 patients) underwent MTC while another group (group H, 33 patients) underwent hepatectomy. The clinical stage of the liver in group M was significantly worse than in group H (p < 0.05), and the maximum diameter of HCC nodules in group M was significantly smaller than group H (p < 0.05). Survival rates of both groups were similar, but the group H disease-free survival rate was significantly better than that of group M (p < 0.05). Furthermore, the interval between treatment and tumor recurrence in group H was significantly longer than for group M (p < 0.05). We believe the more frequent incidence of local recurrence in group M may have been due to incomplete coagulation. Thus, MTC provides a possible new option for local treatment of HCC, but it is important to ensure complete coagulation of the tumors.     

Inhibition of adhesion of type 1 fimbriated Escherichia coli to highly mannosylated ligands

The inhibitory potencies of a number of mannosides, di- and trivalent mannosides, a set of mannose-terminating dendrimers, and five types of mannose-bearing neoglycoproteins were determined by using a binding assay that measures the binding of (125)I-labeled, highly mannosylated neoglycoprotein to a type 1 fimbriated Escherichia coli (K12) strain in suspension. The IC(50) values (the concentration of inhibitor that causes 50 % reduction in the bound (125)I-ligand to E. coli) obtained by this method were much lower than the equivalent values obtained by hemagglutination or in assays that involve microplate immobilization. Two important factors that strongly influence the affinity to E. coli adhesin are: 1) the presence of an alpha-oriented aglycon that has a long aliphatic chain or an aromatic group immediately next to the glycosyl oxygen, and 2) the presence of multiple mannosyl residues that can span a distance of 20 nm or longer on a relatively inflexible structure. The two best inhibitors, which are a highly mannosylated neoglycoprotein with the longest linking arm between a mannose and protein amino group and the largest mannosylated dendrimer (fourth generation), exhibited sub-nM IC(50) values.     

12-channel parallel optical-fiber transmission using a low-drivecurrent 1.3-μm LED array and a p-i-n PD array

Twelve-channel 14-Mb/s/channel 1-km parallel optical-fiber transmission using a 1×12 low-drive-current 1.3-μm light-emitting diode (LED) linear array and an InGaAs p-i-n photodiode linear array, with the LED drive current as low as 12 mAp-p/channel, is discussed. No receiver sensitivity degradation has been observed under simultaneous 12-channel operation. The skew was less than 6 ns after transmission through a 1-km-long 12-channel optical-fiber cable, which was sufficiently small for 14-Mb/s parallel transmission     

An analog front-end chip set employing an electro-optical mixeddesign on SPICE for 5-Gb/s/ch parallel optical interconnection

A chip set composed of a laser-diode driver (LDD) and an optical receiver (RCV), which incorporates a full 2D (reshape, regenerate) function, has been developed by using silicon bipolar technology for a four-channel 5-Gb/s parallel optical transceiver. An electro-optical mixed design on SPICE of the LDD and the LD is accomplished by describing the rate equations of the LD as an electrical circuit. This design accommodates easy connectivity of the LDD chip to the LD in the optical transmitter module without the need for adjustment of the optical waveform. A pseudobalanced transimpedance amplifier (TIA) and feedforward automatic decision threshold control (ATC) in the RCV minimize the number of off-chip bypass capacitors, eliminate the need for any off-chip coupling capacitors, and keep crosstalk less than -50 dB and low cutoff frequency less than 80 kHz. A prototype parallel optical transmitter module and a prototype receiver module, based on the chip set, demonstrated asynchronous four-channel 5-Gb/s operation. The chip set has a throughput of 20 Gb/s with a power dissipation of 1.3 W at a 3.3-V supply     

Glycoblotting-assisted O-glycomics: ammonium carbamate allows for highly efficient o-glycan release from glycoproteins

Glycoblotting, high throughput method for N-glycan enrichment analysis based on the specific chemical ligation between aminooxy/hydrazide-polymers/solids and reducing N-glycans released from whole serum and cellular glycoproteins, was proved to be feasible for selective enrichment analysis of O-glycans of common (mucin) glycoproteins. We established a standard protocol of glycoblotting-based O-glycomics in combination with nonenzymatic chemical treatment to release reducing O-glycans predominantly from various glycoprotein samples. It was demonstrated that the nonreductive condition employing a simple ammonium salt, ammonium carbamate, made glycoblotting-based enrichment analysis of O-glycans possible without significant loss or unfavorable side reactions. A general workflow of glycoblotting using a hydrazide bead (BlotGlyco H), on-bead chemical manipulations, and subsequent mass spectrometry allowed for rapid O-glycomics of human milk osteopontin (OPN) and urinary MUC1 glycoproteins purified from healthy donors in a quantitative manner. It was revealed that structures of O-glycans in human milk OPN were varied with habitual fucosylation and N-acetyllactosamine units. It was also suggested that purified human urinary MUC1 was modified preferentially by sialylated O-glycans (94% of total) with 7:3 ratio of core 1 to core 2 type O-glycans. Versatility of the present strategy is evident because this method was proved to be suited for the enrichment analysis of general biological and clinical samples such as human serum and urine, cultured human cancer cells, and formalin-fixed paraffin-embedded tissue sections. It is our belief that the present protocols would greatly accelerate discovery of disease-relevant O-glycans as potential biomarkers.