Effects of freeze-drying of samples on metabolite levels in metabolome analyses

Freeze-drying (FD) is a useful technique for removing water from biological tissues, such as food samples. Cellular components freeze at once, and the ice sublimates under conditions of high vacuum and low temperatures. Because biological activity is restricted during FD, the degradation of cellular metabolites is often believed to be limited. However, the cellular structure is damaged by several factors, such as the increase in cell volume during freezing, and this has serious effects on the levels of some cellular metabolites. We studied these effects of FD on metabolite levels when using it as a sample preparation step in metabolome analysis. We observed significant decreases in the levels of some metabolites, such as succinate and choline, in Arabidopsis and pear, respectively. We also found that the effects of FD on certain metabolite levels differed between Arabidopsis plants and pear fruits. These results suggest that it is necessary to confirm the metabolite recovery in each sample species when FD is used for sample preparation.     

Optical properties of a waveguide written inside a LiTaO3 crystal by irradiation with focused femtosecond laser pulses

Optical waveguides were fabricated by modifying the optical properties inside a LiTaO₃ crystal by irradiation with femtosecond laser pulses, and the performance and optical properties of the waveguide were investigated. On the basis of near-field pattern of the light guided through the waveguides, the optimum writing conditions such as the pulse energy and the pulse duration were determined. The waveguide written inside a LiTaO₃ crystal had a strong polarization dependence of guided light. Observation by a polarized microscope suggested that the stress distribution around the photoexcited region should be responsible for the polarization dependence of guided light. In addition, the second harmonic generation from a laser beam passing through the waveguide was observed, which suggests that the ferroelectric properties of LiTaO₃ were preserved after the photoexcitation.     

Amino acids and peptides. XXIX. Synthesis of peptide fragments related to active center of eglin c and studies on the relationship between their structure and their inhibitory activity against cathepsin G and alpha-chymotrypsin

H-Ser-Pro-Val-Thr-Leu-Asp-Leu-Arg-Tyr-OMe, corresponding to the sequence 41-49 of eglin c, inhibited human leukocyte cathepsin G and alpha-chymotrypsin. In order to gain further insight into the relationship between the structure and the inhibitory activity against cathepsin G and alpha-chymotrypsin, peptide fragments related to the above nonapeptide were synthesized by a conventional solution method and their inhibitory activities were examined. The smallest peptide which exhibited inhibitory effects on the above enzymes was H-Pro-Val-Thr-Leu-OMe, corresponding to the sequence 42-45 of eglin c.     

Electron-transfer polymers. XL. Redox polyamides

By condensing a hydroquinone bis-lactone of 1,4-dihydroxybenzene-2,5-bis(ethyl-2′-carboxylic acid) with diamines such as hexamethylene diamine, piperazine, 4-aminoethylpiperidine, or 1,3-di-(4′-piperidinyl) propane, redox polyamides can be prepared. The lactone functions protect the hydroxyl groups until the polymerization occurs at which point, due to the opening of the lactone rings, free hydroquinone hydroxyls appear. The resulting polymer is oxidizable. When the oxidized polymer is reduced the viscosity is higher than that of the original reduced polymer.     

Das papierchromatographische Verhalten und den Nachweis zahlreicher Phenolk?rper

Ohne Zusammenfassung     

Preparation of new biomedical materials and their application in clinics

Biomaterials – tissues interaction is important to study in biomaterials science. The information is indispensable to make medical devises and artificial organs and to predict their performance. It is also very useful to consider a hypothesis to design new biomaterials. New materials have brought big progress in the society as we know. There are few biomaterials specially designed to use in biomedical fields. The most important effort must be preparation of biocompatible materials, that must be essential to develop new type high performance devices and artificial organs. Preparation of new dental biomaterials used in bonding of prostheses to dentinal tissues that require fundamental change in modern dentistry and a new methacrylate, MPC, to develop promising several kinds of biomaterials with unusually excellent biocompatibility and functions are going to present. Topics in tissue engineering are also discussed.     

Synthesis and Hierarchical Self‐Assembly of Diphenylalanine‐Based Homopolymer and Copolymers By RAFT Polymerization

Dipeptide diphenylalanine has attracted significant research interests because of its ability to self‐assemble into various nanostructures such as nanotubes, nanowires, and nanoribbons. In this article, we present the synthesis and self‐assembly of a novel diphenylalanine‐based homopolymer and block/random copolymers by the reversible addition–fragmentation chain transfer (RAFT) polymerization of an acrylamide having a dipeptide moiety. The RAFT polymerization of N‐acryloyl‐l ,l ‐diphenylalanine (A‐Phe‐Phe‐OH) afforded novel amino acid‐based polymers with predetermined molecular weights and relatively narrow‐molecular weight distributions. The hierarchical self‐assembled structures of poly(A‐Phe‐Phe‐OH), which involve nanorods, larger nanofiber‐like microcrystals, and fiber bundles, were characterized by atomic force microscopy (AFM), transmission electron microscopy, scanning electron microscopy, and dynamic light scattering measurements. The circular dichroic measurements of poly(A‐Phe‐Phe‐OH) revealed its characteristic chiroptical property, which is affected by the nature of the solvents and the addition of urea and salts via hydrophobic, hydrogen bonding, and electrostatic interactions. Thermo‐ and pH‐responsive block and random copolymers composed of A‐Phe‐Phe‐OH and N‐isopropylacrylamide were synthesized by RAFT polymerization, and the thermoresponsive properties and assembled structures of the resulting copolymers were investigated by AFM and turbidity measurements. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2562–2574     

An ionicity diagram for the family of [{Ru2(CF3CO2)4}2(TCNQR(x))] (TCNQR(x) = R-substituted 7,7,8,8-tetracyano-p-quinodimethane)

A diagram of energies between the HOMO of donor (D) and LUMO of acceptor (A) vs.ΔE(1/2)(DA) (= E(1/2)(D) - E(1/2)(A): E(1/2) = first-redox potential) clearly demonstrates the ionicity in the series of D/A assemblies, [{Ru(2)(CF(3)CO(2))(4)}(2)(TCNQR(x))]·n(solv) (TCNQR(x) = 2,5- or 2,3,5,6-R-substituted 7,7,8,8-tetracyano-p-quinodimethane; R(x) = H(4), F(2), Cl(2), Br(2), F(4), Me(2), (OMe)(2)).     

Photolysis and Thermolysis of Platinum(IV) 2,2′‐Bipyridine Complexes Lead to Identical Platinum(II)–DNA Adducts

Two Pt^IV and two Pt^II complexes containing a 2,2′‐bipyridine ligand were treated with a short DNA oligonucleotide under light irradiation at 37 °C or in the dark at 37 and 50 °C. Photolysis and thermolysis of the Pt^IV complexes led to spontaneous reduction of the Pt^IV to the corresponding Pt^II complexes and to binding of Pt^II 2,2′‐bipyridine complexes to N7 of guanine. When the reduction product was [Pt(bpy)Cl₂], formation of bis‐oligonucleotide adducts was observed, whereas [Pt(bpy)(MeNH₂)Cl]⁺ gave monoadducts, with chloride ligands substituted in both cases. Neither in the dark nor under light irradiation was the reductive elimination process of these Pt^IV complexes accompanied by oxidative DNA damage. This work raises the question of the stability of photoactivatable Pt^IV complexes toward moderate heating conditions.