Poly‐ε‐Lysine Modified Nanocarbon Film Electrodes for LPS Detection

We developed an electrochemical system for detecting lipopolysaccharide (LPS) that uses an ultraflat nanocarbon film electrode modified with poly‐ε‐lysine with a high affinity to LPS. LPS was captured on the modified electrode, and then ferrocene labeled polymyxin B (FcPMB) was captured on the LPS adsorbed electrode via the LPS‐PMB affinity interaction. The adsorbed FcPMB provided an amplified response with Fe²⁺ ions, and the current response was dependent on the amount of captured LPS (LOD=2.0 ng/mL). This was due to the efficient accumulation of the obtained current for LPS and the very low noise made possible by the ultraflat surface.     

4-(Pyrrolidinyl)methoxybenzoic acid derivatives as a potent, orally active VLA-4 antagonist

A novel series of benzoic acid derivatives as VLA-4 antagonists were synthesized. Optimization, focusing on activity and lipophilicity needed for cell permeability, resulted in the identification of 15b and 15e with good activity (IC50 = 1.6 nM each) and moderate lipophilicity (Log D = 2.0, 1.8). Furthermore, 15e demonstrated efficacy in murine asthma model by an oral dose of 30 mg/kg.     

Elucidation of the Role of the Complex in Hydride Transfer Reaction between Methylene Blue and 1-Benzyl-1,4-dihydronictinamide by Effect of γ-Cyclodextrin

The kinetics of the hydride transfer reaction between Methylene Blue (MB⁺) and 1-benzyl-1,4-dihydronicotinamide (BNAH) were studied in 10% ethanol-90% water mixed solvents containing β- and γ-cyclodextrins (β-CD and γ-CD). The pseudo-first order rate constant shows kinetic saturation at high initial concentration of BNAH. This indicates the formation of a complex between MB⁺ and BNAH. The reaction was suppressed by addition of β-CD, but enhanced by addition of γ-CD. MB⁺ and BNAH were separately accommodated within the β-CD cavity and the cavity walls may protect the activity site of the reactants. On the other hand, in the MB⁺-BNAH-γ-CD system, the inclusion of the complex between MB⁺ and BNAH with γ-CD occurred. This effect of γ-CD can distinguish between the productive and non-productive nature of the complex.     

SUPER TOUGH GELS WITH A DOUBLE NETWORK STRUCTURE

 Living tissues work with fantastic functions in soft and wet gel-like state. Thus, hydrogels have attracted much attention as excellent soft & wet materials, suitable for making artificial organs for medical treatments.However, conventional hydrogels are mechanically too weak for practical uses. We have created double network (DN) hydrogels with extremely high mechanical strength in order to overcome this problem. DN gels are interpenetrating network (IPN) hydrogels consisting of rigid polyelectrolyte and soft neutral polymer. Their excellent mechanical properties cannot be explained by the standard fracture theories. In this paper, we discuss about the toughening mechanism of DN gels in accordance with their characteristic behavior, such as large hysteresis and necking phenomenon. We also describe the results on tissue engineering application of DN gels.     

Structure and properties of ethyl (2-benzimidazolyl)cyanoacetimidate

The revision of the structure of hydrolytic product from 4-cyano-1-ethoxypyrirnido[1,6-a]benzimidazole (1) and the properties of ethyl (2-benzimidazolyl)cyanoacetimidate (3a) are described.     

On the unstable homotopy spectral sequences

We shall study the relation between the unstable homotopy spectral sequence associated with the cell decomposition of the source space and the one associated with the Postnikov decomposition of the target space. It is proved that the Maunder's result holds for these two types of spectral sequences. This result will be exploited to study the differentials of these spectral sequences and we obtain a generalization of a theorem due to Atiyah-Hirzebruch and Dold. Making use of these spectral sequences with the convergence lemma, some results on the phantom maps and the homotopy groups of map_*(Y, X) will be proved.     

Influence of the solvent on nature of gate effect in molecularly imprinted membrane

The solute diffusive permeability in a thin layer of a molecularly imprinted polymer (MIP) is affected by specific binding of the MIP with a template. This phenomenon, termed the "gate effect," would be widely applicable for the development of novel biomimetic sensors. However, the mechanism underlying the gate effect is not totally understood. We present here investigation of the role of specific adsorption of a template and solution content in MIPs on the gate effect. A molecularly imprinted self-supporting membrane was formed by copolymerization of methacrylic acid, 2-vinylpyridine, and triethyleneglycol dimethacrylate in the presence of L- (or D-) phenylalanine as a template. The template adsorbed by membrane with degree of enantio-selectivity in a mixed solvent of methanol and water. The amount of adsorption and binding selectivity showed little sensitivity to the solvent composition. The solution content in the membrane increased with increasing the methanol concentration of the solvent following a sigmoid curve with an inflection point at methanol concentration of 20 wt.%. The content increased in the presence of the template at methanol concentrations higher than the inflection point, and decreased at lower methanol concentrations. The creatinine permeability across the membrane estimated by batchwise dialysis increased in the presence of the template at 50 wt.% methanol in the solvent, and did not change at 20 wt.%. There was no permeability for creatinine in the pure water solvent. Both the solution content and the permeability were not affected by the presence of the enantiomer of the template. The results show that the choice of solvent controls more strongly the nature of the gate effect than the specific binding of the template.     

Palladium-catalyzed selective cross-addition of triisopropylsilylacetylene to internal and terminal unactivated alkynes

Dinuclear and mononuclear palladium complexes having N,N'-bis[2-(diphenylphosphino)phenyl]amidinate (DPFAM) as a ligand catalyzed the cross-addition of triisopropylsilylacetylene (TIPSA) to unactivated internal alkynes, giving enynes selectively. When palladium catalysts having PPh3, TDMPP, dppe, or dppf were used, dimers of TIPSA were obtained as major products. The reactions of TIPSA with several terminal alkynes also gave cross-adducts selectively, although the yields were moderate.     

An antisymmetric problem of a penny-shaped crack in a piezoelectric medium

Summary  An exact, three-dimensional analysis is developed for a penny-shaped crack in an infinite transversely isotropic piezoelectric medium. The crack is assumed to be parallel to the plane of isotropy, with its faces subjected to a couple of concentrated normal forces and a couple of point electric charges that are antisymmetric with respect to the crack plane. The fundamental solution of a concentrated force and a point charge acting on the surface of a piezoelectric half-space is employed to derive the integral equations for the general boundary value problem. For the above antisymmetric crack problem, complete expressions for the elastoelectric field are obtained. A numerical calculation is finally performed to show the piezoelectric effect in piezoelectric materials. It is noted here that the present analysis is an extension of Fabrikant's theory for elasticity. Received 30 August 1999; accepted for publication 1 March 2000