Medical application of carbon-nanotube-filled nanocomposites: the microcatheter

Carbon nanotubes hold great promise for use in biomedical fields. Among numerous potential applications, including DNA and protein sensors, bioseparators, biocatalysts, and tissue scaffolds, this article emphasizes the use of carbon-nanotube-filled polymer composites as medical devices, namely, microcatheters. The currently hot topic of the biocompatibility (e.g., toxic properties) of carbon nanotubes is discussed. In addition, critical issues that must be clarified for the full utilization of current carbon-nanotube science and technology in biomedical fields are discussed.     

Low‐Noise Fully Differential Amplifiers Using JFET‐CMOS Integration Technology for Smart Sensors

In this paper, CMOS‐based low‐noise amplifiers with JFET‐CMOS technology for high‐resolution sensor interface circuits are presented. A differential difference amplifier (DDA) configuration is employed to realize differential signal amplification with very high input impedance, which is required for the front‐end circuit in many sensor applications. Low‐noise JFET devices are used as input pair of the input differential stages or source‐grounded output load devices, which are dominant in the total noise floor of DDA circuits. A fully differential amplifier circuit with pure CMOS DDA and three types of JFET‐CMOS DDAs were fabricated and their noise performances were compared. The results show that the total noise floor of the JFET‐CMOS amplifier was much lower compared to that of the pure CMOS configuration. The noise‐reduction effect of JFET replacement depends on the circuit configuration. The noise reduction effect by JFET device was maximum of about − 18 dB at 2.5 Hz. JFET‐CMOS technology is very effective in improving the signal‐to‐noise ratio (SNR) of a sensor interface circuit with CMOS‐based sensing systems. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Metabolism of odd-numbered fatty acids and even-numbered fatty acids in mouse

Fatty acids are converted into energy via beta-oxidation. Although almost all natural occurring fatty acids are even-numbered, there are some odd-numbered fatty acids too. The details of the metabolism rate of odd-numbered fatty acids, however, are not clear. In the present study, we simultaneously administered a triacylglycerol containing four types of labeled even-numbered (palmitic acid and stearic acid) and odd-numbered (pentadecanoic acid and heptadecanoic acid) fatty acids to mice to compare the rates of their metabolism. The rates of metabolism were evaluated based on the accumulation of the labeled fatty acids in the small intestine epithelium, liver, and epididymal fat. Odd-numbered fatty acids accumulated mainly in the epididymal fat. In contrast, there was no accumulation of even-numbered fatty acids observed in the small intestine epithelium, liver, or epididymal fat. These results suggest that odd-numbered fatty acids might not be favorable substrates for beta-oxidation-related enzymes.     

Characterization of Catalase from Psychrotolerant Psychrobacter piscatorii T-3 Exhibiting High Catalase Activity

A psychrotolerant bacterium, strain T-3 (identified as Psychrobacter piscatorii), that exhibited an extraordinarily high catalase activity was isolated from the drain pool of a plant that uses H(2)O(2) as a bleaching agent. Its cell extract exhibited a catalase activity (19,700 U·mg protein(-1)) that was higher than that of Micrococcus luteus used for industrial catalase production. Catalase was approximately 10% of the total proteins in the cell extract of the strain. The catalase (PktA) was purified homogeneously by only two purification steps, anion exchange and hydrophobic chromatographies. The purified catalase exhibited higher catalytic efficiency and higher sensitivity of activity at high temperatures than M. luteus catalase. The deduced amino acid sequence showed the highest homology with catalase of Psycrobacter cryohalolentis, a psychrotolelant bacterium obtained from Siberian permafrost. These findings suggest that the characteristics of the PktA molecule reflected the taxonomic relationship of the isolate as well as the environmental conditions (low temperatures and high concentrations of H(2)O(2)) under which the bacterium survives. Strain T-3 efficiently produces a catalase (PktA) at a higher rate than Exiguobacterium oxidotolerans, which produces a very strong activity of catalase (EktA) at a moderate rate, in order to adapt to high concentration of H(2)O(2).     

Effect of the Helical Tether of a Resin‐Supported Peptide Catalyst for Friedel–Crafts‐Type Alkylation in Water

A detailed investigation of the helical part of the resin‐supported peptide catalyst possessing a turn motif and helical unit was conducted to clarify the structure‐activity relationship. The peptide catalyst with an α‐ or 3₁₀‐helical tether was effective for an enantioselective Friedel–Crafts‐type alkylation in water. From the spectral analysis of the peptide with an optimum sequence, it was demonstrated that the helical moiety of the peptide catalyst played a role for stabilizing a terminal turn structure.     

Molecular properties of the two-component cell lysis system encoded by prophage phigaY of Lactobacillus gasseri JCM 1131T: cloning, sequencing, and expression in Escherichia coli

Shotgun cloning of the Lactobacillus gasseri JCM 1131T whole DNA yielded two recombinant plasmids, p118gaY1 and p118gaY2, which directed cell lysis activity. Sequencing analysis revealed that the two plasmids carried almost identical inserted genes in following orders (truncated genes, in parentheses): in p118gaY1, (orf149)-orf92-holgaY-lysgaY-orf35-attL-(mnaAgaY1); in p118gaY2, (orfXgaY1)-orf169-orf149-orf92-holgaY-lysgaY-orf35-attP-(intgaY). The lysgaY-encoded protein (designated as LysgaY, 33.7 kDa) showed significant homology with putative muramidases (peptidoglycan-degrading enzyme) of the Lactobacillus phage phiadh, Lj965, Lj928, LL-H, mv4, and mv1. By zymogram analysis, LysgaY overproduced in Escherichia coli exhibited lytic activity towards 17 Gram-positive bacterial strains, including lactobacilli, lactococci, and staphylococci. The holgaY-encoded protein (15.7 kDa) contained three potential transmembrane helices, resembling putative holins (cytoplasmic membrane-disrupting protein) of Lj928 and Lj965. On the other hand, another clone p118gaYR obtained by EcoRI-shotgun cloning carried the (ptsCgaY1)-attR-(intgaY) genes. Three sequences, attL, attP, and attR, had a 47-bp common (core) sequence, and the core of attR was located in 3' region of a potential tRNA(Arg) gene. These results suggested that (i) attL and attR are phage-host junctions, left- and right-arms, respectively, (ii) attP is a phage attachment site, and (iii) intgaY is an integrase gene for phage integration and/or excision. After mitomycin C-induction, phage particles were demonstrated by electron microscopy. The prophage (phigaY) is somewhat leaky in the host, and has the two-component lysis system (HolgaY-LysgaY), closely resembling that of Lj928 as well as Lj965.     

Influence of side chain length on fluorescence intensity of ROMP-based polymeric nanoparticles and their tumor specificity in in-vivo tumor imaging

In this study, amphiphilic brush-like copolymers conjugated with short alkyl or long polymeric chains of various lengths are synthesized using ring-opening metathesis polymerization (ROMP) of substituted norbornadiene monomers followed by chemical transformations. These amphiphilic copolymers form spherical self-assemblies in aqueous media with diameters of 132-244 nm. The low critical aggregation concentration of these assemblies (2.5 × 10(-3) -1.4 × 10(-5) g/L) indicates that they are quite stable in dilute conditions. An appropriate length of polymer side chain that conjugates the polymer backbone with a hydrophobic ICG (indocyanine green) moiety enhanced the fluorescence intensities of these self-assemblies in aqueous solution as well as in tumor-bearing mice. A longer side chain conjugated with tumor targeting agents could significantly affect the tumor specificity of self-assemblies to a greater extent. The self-assemblies bearing hydrophilic tumor targeting agents, such as a glucosamine molecule and a cyclic RGD (arginine-glycine-asparatic acid) peptide, accumulated in tumor tissues with high selectivity, while those having a hydrophobic targeting agent, such as folate moieties, accumulated in tumor sites with low selectivity. The results demonstrated here unambiguously indicate that the fluorescence intensity and tumor specificity of self-assemblies are strongly affected by the length of side chains that conjugate with dyes and targeting agents.     

Fabrication and Pore Size Control of Large-Pore Mesoporous Silica Particles through a Solvent Evaporation Process

Large-pore mesoporous silica particles were synthesized through a solvent evaporation process using hydrophobic fumed silica particles and tetraethyl orthosilicate (TEOS) as silica sources. The solvent evaporation of an ethanol solution of fumed silica particles, TEOS, HCl and triblock copolymer (F127) resulted in mesoporous silica particles with pores with sizes of about 7 nm. In addition, the interplanar spacing of the mesoporous silica particles can be controlled by changing the solvent evaporation temperatures.     

Candidate Biomarkers for Genetic and Clinicopathological Diagnosis of Endometrial Cancer

The recent increase in the frequency of endometrial cancer has emphasized the need for accurate diagnosis and improved treatment. The current diagnosis is still based on conventional pathological indicators, such as clinical stage, tumor differentiation, invasion depth and vascular invasion. However, the genetic mechanisms underlying endometrial cancer have gradually been determined, due to developments in molecular biology, leading to the possibility of new methods of diagnosis and treatment planning. New candidate biomarkers for endometrial cancer include those for molecular epigenetic mutations, such as microRNAs. These biomarkers may permit earlier detection of endometrial cancer and prediction of outcomes and are likely to contribute to future personalized therapy for endometrial cancer.     

Analysis of degradation in PEMFC caused by cell reversal during air starvation

The damage caused by cell reversal during proton exchange membrane fuel cells (PEMFCs) operation with air starvation was investigated by a single-cell experiment. Samples from degraded membrane–electrode assemblies (MEAs) were characterized. The loss of electrochemical surface area of the cathode platinum was detected by in situ cyclic voltammetry, and platinum sintering was detected by transmission electron microscopy (TEM) analysis. Degradation at the anode was not detected in the chemical analysis of the anode catalyst layer of MEA samples by energy dispersive X-ray analysis (EDX) and TEM. An obvious decrease in the performance of PEMFC was observed in a sample degraded by cell reversal for 120 min.