Cell-based screening strategy in the search for bioactive microbial secondary metabolites Utilization of microbial and animal cells with special functions

Here we present results obtained in our group from cell-based screenings of microbial secondary metabolites using intact microbial and mammalian cells having specific functions. We present summaries of the following five categories of compounds and the strategies that were used to identify them. (1) Antibacterial agents targeting cell wall peptidoglycan synthesis as well as active agents against organisms other than bacteria were identified by a combination of Bacillus subtilis and Mycoplasma as test organisms. (2) Antimetabolites, such as herbicidal agents targeting glutamine synthase, were identified using B. subtilis grown on minimal medium with or without the addition of glutamine and folate inhibitors by combination of B. subtilis and Enterococcus faecium, which have distinct folate metabolic pathways. (3) Among inhibitors of lipid metabolism, acyl-CoA synthetase inhibitors were identified using two mutants of C. lipolytica with different deletion sites in the fatty acid metabolic pathways, HMG-CoA synthase inhibitors were identified using Vero cells cultured in the presence and absence of mevalonate, and anti-atherosclerosis agents were identified using macrophages. (4) IL-6 inhibitors were detected by a combination of IL- 6-dependent and independent murine hybridoma MH60 cells, and (5) Small molecules with TNF-like activities were identified using a mouse neuroblastoma cell line. Some advantages of such screening method and the significance of the identified compounds are discussed.     

Control of diameter,morphology, and structure of PVDF nanofiber fabricated by electrospray deposition

Poly(vinylidene fluoride) (PVDF) nanofibers were prepared by electrospray deposition (ESD). To control the diameter, morphology, and structure of PVDF nanofibers, some parameters were investigated, such as polymer concentration, nozzle‐to‐ground collector distance, feeding rate of the polymer solution, and applied voltage. The fabricated fiber was 80–700 nm in diameter. The increase in the polymer concentration caused an increase in the polymer viscosity and fiber diameter. At low polymer concentration (5 wt %), polymer nanoparticles were formed. An increase in applied voltage will increase the fiber diameter. Variation in the nozzle‐to‐ground collector distance did not result in significant changes in the fiber diameter. Increase in the feeding rate of the polymer solution decreased the fiber diameter. Differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD) measurements showed that the melting point and total crystallinity were decreased. Fourier transform infrared spectroscopy (FTIR) measurement revealed that ESD process induced the formation of the oriented β‐phase PVDF structures. It was also demonstrated that the addition of hydrofluorocarbon solvent to polymer solution remarkably enhanced the formation of β‐phase crystalline structure of PVDF nanofiber. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 779–786, 2006     

Fundamental solution of a higher step Grushin type operator

We examine a class of Grushin type operators _Pk$P_k$ where k∈_N0$k\in {\mathbb{N}}_0$ defined in (1.1). The operators _Pk$P_k$ are non-elliptic and degenerate on a sub-manifold of R^N+?${\mathbb{R}}^{N+?}$. Geometrically they arise via a submersion from a sub-Laplace operator on a nilpotent Lie group of step k+1$k+1$. We explain the geometric framework and prove some analytic properties such as essential self-adjointness. The main purpose of the paper is to give an explicit expression of the fundamental solution of _Pk$P_k$. Our methods rely on an appropriate change of coordinates and involve the theory of Bessel and modified Bessel functions together with Weber's second exponential integral.     

Next-Generation NAMPT Inhibitors Identified by Sequential High-Throughput Phenotypic Chemical and Functional Genomic Screens

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Trace level determination of polycyclic aromatic hydrocarbons in river water with automated pretreatment HPLC

A novel on‐line pretreatment pump‐injection HPLC system for polycyclic aromatic hydrocarbons is proposed. We report novel pump‐injection HPLC‐based on‐line SPE with a specially designed pretreatment column for the determination of trace amounts of chemical substances in surface water. Polycyclic aromatic hydrocarbons are well known for strong carcinogenicity and thus a severe concentration control is required for drinking water and/or river water, which is the main resource of tap water. We found it possible to detect ng/L levels of polycyclic aromatic hydrocarbons by using pump‐injection column switching HPLC with fluorescence detection. To avoid the phenomenon, in which polycyclic aromatic hydrocarbons can be often adsorbed on the surface of flow lines of HPLC by their highly hydrophobicity especially resin‐made parts in sample delivery pump, we employed “autodilution” device that provides reliable recovery and repeatability. Additionally, real water samples were collected and then the spiked polycyclic aromatic hydrocarbons were determined at ng/L levels.     

Technology of electrochemical impedance spectroscopy for an energy-sustainable society

Electrochemical impedance spectroscopy has been widely used to understand the chemistry and physics of battery systems. This review covers electrochemical impedance spectroscopy used for the interpretation of impedance data of lithium-ion batteries (LIBs) from advanced equivalent circuit models to the mathematical model, which is developed by John Newman. In addition, as a method to realize an energy-sustainable society using diagnostics based on the combination of LIBs and electrochemical impedance spectroscopy, on-board diagnostics of battery packs are achieved based on an input signal generated by a power controller in a battery management system instead of the conventionally used frequency response analyzer. The diagnostic system is applicable to energy management systems which are installed in homes, buildings, and communities, accumulating the impedance data on state of health of LIBs. Finally, a future possibility regarding the diagnostics of battery packs coupled with the machine learning of impedance data is introduced.     

New ferroelectric liquid crystals with a trifluoromethyl group

Abstract

New chiral dopants, possessing a trifluoromethyl group, have been synthesized. These dopants have different polar groups, located between the chiral centre and the diphenylacetylene core. The polar part is chosen from ester, methylene ether and ether linkages. Each new chiral dopant was mixed with a non-chiral liquid crystal mixture or a ferroelectric liquid crystal mixture, and their transition temperatures and electrooptic properties measured. The largest spontaneous polarization, 4·1 nC cm^?2, was obtained at 25°C for the ferroelectric liquid crystal mixture in which the dopant, with a methylene ether linkage, was incorporated. Molecular orbital calculations (MNDO method) for the dopants show that the calculated dipole moments are correlated with the measured spontaneous polarization, and the calculated results explain the experimental results quite well. In addition, it has been found that the conformation of the chiral part is an important factor which affects the magnitude of spontaneous polarization.     

Spontaneous formation of mesoporous silica films using non-surfactant template, and optimization with Doehlert designs, for adsorbent for polycyclic aromatic hydrocarbons

To prepare mesoporous silica thin-films by a simple and environmentally friendly pathway, spontaneous formation of silica thin-films in a sol–gel solution without surfactants was studied. The silica thin-films were prepared by immersing a glass substrate, such as a cylindrical test-tube, into a sol–gel solution containing tetraethoxysilane, water, acetic acid, 2-propanol, and triethylene glycol as a pore-forming agent. The resulting thin-films were transparent. The presence of mesopores was confirmed by field-emission scanning electron microscopy, atomic-force microscopy and nitrogen adsorption–desorption isotherms. The Barrett–Joyner–Halenda plot from the adsorption branch of the isotherms indicated that the pore diameter was 2.6 nm. To illustrate the potential use of the film as an adsorbent, the extraction of polycyclic aromatic hydrocarbons was conducted using the chemically modified silica thin-film coated on a test-tube. The composition of the sol–gel solution was optimized using experimental design, i.e., Doehlert design, and recovery of polycyclic aromatic hydrocarbons.     

The spectral broadening of a blue optical pulse and the modulation of a pulse waveform in a photonic crystal fiber by induced-phase modulation

By copropagating a fundamental pulse and a blue second-harmonic pulse from a Ti:Sapphire oscillator in a photonic crystal fiber (PCF), the spectral broadening of the blue second-harmonic pulse from 380 to 600 nm has been observed by use of induced-phase modulation (IPM) at a 78-MHz repetition rate. From the experimental and the calculated delay time dependence of spectral intensities, it was inferred that the largest spectral broadening was observed when the second-harmonic pulse interacted with the fundamental pulse near the input end of a PCF, where the fundamental pulse was compressed temporally due to self-phase modulation and negative group velocity dispersion. From the simulation, the mechanism of spectral broadening was clarified and the fission process of the fundamental pulse was shown to be influenced strongly by IPM.