Photolithographic fabrication of poly(ethylene glycol) microstructures for hydrogel-based microreactors and spatially addressed microarrays

We describe the fabrication of poly(ethylene glycol) diacrylate (PEG-DA) hydrogel microstructures with a high aspect ratio and the use of hydrogel microstructures containing the enzyme beta-galactosidase (beta-Gal) or glucose oxidase (GOx)/horseradish peroxidase (HRP) as biosensing components for the simultaneous detection of multiple analytes. The diameters of the hydrogel microstructures were almost the same at the top and at the bottom, indicating that no differential curing occurred through the thickness of the hydrogel microstructure. Using the hydrogel microstructures as microreactors, beta-Gal or GOx/HRP was trapped in the hydrogel array, and the time-dependent fluorescence intensities of the hydrogel array were investigated to determine the dynamic uptake of substrates into the PEG-DA hydrogel. The time required to reach steady-state fluorescence by glucose diffusing into the hydrogel and its enzymatic reactions with GOx and HRP was half the time required for resorufin beta-D-galactopyranoside (RGB) when used as the substrate for beta-Gal. Spatially addressed hydrogel microarrays containing different enzymes were micropatterned for the simultaneous detection of multiple analytes, and glucose and RGB solutions were incubated as substrates. These results indicate that there was no cross-talk between the beta-Gal-immobilizing hydrogel micropatches and the GOx/HRP-immobilizing micropatches.     

Increased alpha2,3-sialylation and hyperglycosylation of N-glycans in embryonic rat cortical neurons during camptothecin-induced apoptosis

Alterations in the glycan chains of cell surface glycoconjugates are frequently involved biological processes such as cell-cell interaction, cell migration, differentiation and development. Cultured embryonic (E18) rat cortical neurons underwent apoptosis in response to camptothecin, and lectin histochemistry showed that binding to apoptotic neurons of FITC-conjugated Maackia amurensis agglutinin (MAA), which is specific for terminal alpha2,3-sialic acid residues, increased progressively with increasing concentrations of camptothecin. Analysis of the total proteins of apoptotic neurons by SDS-PAGE, and lectin blotting using HRP-labeled MAA, revealed that the expression of terminal alpha2,3-sialic acid residues on an unknown protein with an apparent molecular mass of 25.6 kDa also increased in apoptotic neurons. NP-HPLC analysis of the total cellular N-glycans of normal and apoptotic neurons demonstrated that the expression of structurally simpler biantennary types of N-glycans fell by 49% during apoptosis whereas the more branched triantennary types of N-glycans with terminal sialic acid residues increased by up to 59%. These results suggest that increased surface expression of alpha2,3-sialic acid residues and hyperglycosylation of N-glycans is a common feature of cellular responses to changes in cell physiology such as tumorigenesis and apoptosis.     

Testis-specific expression and genomic multiplicity of the rat Rtdpoz genes that encode bipartite TRAF- and POZ/BTB-domain proteins

Based on bioinformatics analysis, we previously hypothesized the existence of a bipartite TDPOZ protein family members of which carry the TRAF domain (TD) and POZ/BTB [Huang, C.-J., Chen, C.-Y., Chen, H.-H., Tsai, S.-F., Choo, K.-B., 2004. TDPOZ, a family of bipartite animal and plant proteins that contain the TRAF (TD) and POZ/BTB domains. Gene 324, 117-127.]. Conservation in animals and plants suggests important biological functions for the putative TDPOZ proteins. In this work, we report testis-specific expression of two new Tdpoz members, Rtdpoz-T1 and -T2, of the rat genome; the result clearly indicates that members of the hypothetical gene family are, indeed, expressed. T1 and T2 cDNA sequences were derived by rapid amplification of cDNA ends (RACE). The exons of the genes were determined by queries of the rat genome sequence draft and selectively confirmed in splicing assays. The results indicate that T1 and T2 share a common leader exon indicative of alternative splicing, and that the genes are uninterrupted by introns in their respective coding sequences. Database interrogations also reveal a combined 297 hits of Rtdpoz-like sequences on 7 chromosomes; however, the bulk of the hits (264) and 26 putative TDPOZ-encoding genes, including T1 and T2, are found in a approximately 2.5 Mb cluster in the Rn2_2148 supercontig on chromosome 2. Our data signify retrotransposition in the generation and expansion of the Rtdpoz repertoire in the rat genome. We also anticipate spatio-temporal-specific expression of many more TDPOZ members in the rat or other animals and plants.     

Environmental Factors Associated with the Eukaryotic Microbial Diversity of Ulleungdo Volcanic Island in South Korea

Microbiology - Ulleungdo is a volcanic island with an oceanic climate seasonally affected by warm and cold currents. The freshwater ecosystems of Ulleungdo Island act as an ecological indicator...     

Enhancement in current density and energy conversion efficiency of 3-dimensional MFC anodes using pre-enriched consortium and continuous supply of electron donors

Using a pre-enriched microbial consortium as the inoculum and continuous supply of carbon source, improvement in performance of a three-dimensional, flow-through MFC anode utilizing ferricyanide cathode was investigated. The power density increased from 170 W/m³ (1800 mW/m²) to 580 W/m³ (6130 mW/m²), when the carbon loading increased from 2.5 g/l-day to 50 g/l-day. The coulombic efficiency (CE) decreased from 90% to 23% with increasing carbon loading. The CEs are among the highest reported for glucose and lactate as the substrate with the maximum current density reaching 15.1 A/m². This suggests establishment of a very high performance exoelectrogenic microbial consortium at the anode. A maximum energy conversion efficiency of 54% was observed at a loading of 2.5 g/l-day. Biological characterization of the consortium showed presence of Burkholderiales and Rhodocyclales as the dominant members. Imaging of the biofilms revealed thinner biofilms compared to the inoculum MFC, but a 1.9-fold higher power density.     

Effects of intima stiffness and plaque morphology on peak cap stress

Background  

Rupture of the cap of a vulnerable plaque present in a coronary vessel may cause myocardial infarction and death. Cap rupture occurs when the peak cap stress exceeds the cap strength. The mechanical stress within a cap depends on the plaque morphology and the material characteristics of the plaque components. A parametric study was conducted to assess the effect of intima stiffness and plaque morphology on peak cap stress.