Novel bioactive peptides,PF1171F and PF1171G,from unidentified ascomycete OK-128

Two cyclic peptides, PF1171F (1) and PF1171G (2), were isolated from okara fermented with the unidentified ascomycete OK-128, and their structures were determined by NMR, MS, and Marfey amino acid analysis. Both peptides showed paralytic activity against silkworms.     

Environment-sensitive fluorophores with benzothiadiazole and benzoselenadiazole structures as candidate components of a fluorescent polymeric thermometer

An environment-sensitive fluorophore can change its maximum emission wavelength (λ(em)), fluorescence quantum yield (Φ(f)), and fluorescence lifetime in response to the surrounding environment. We have developed two new intramolecular charge-transfer-type environment-sensitive fluorophores, DBThD-IA and DBSeD-IA, in which the oxygen atom of a well-established 2,1,3-benzoxadiazole environment-sensitive fluorophore, DBD-IA, has been replaced by a sulfur and selenium atom, respectively. DBThD-IA is highly fluorescent in n-hexane (Φ(f) =0.81, λ(em) =537?nm) with excitation at 449?nm, but is almost nonfluorescent in water (Φ(f) =0.037, λ(em) =616?nm), similarly to DBD-IA (Φ(f) =0.91, λ(em) =520?nm in n-hexane; Φ(f) =0.027, λ(em) =616?nm in water). A similar variation in fluorescence properties was also observed for DBSeD-IA (Φ(f) =0.24, λ(em) =591?nm in n-hexane; Φ(f) =0.0046, λ(em) =672?nm in water). An intensive study of the solvent effects on the fluorescence properties of these fluorophores revealed that both the polarity of the environment and hydrogen bonding with solvent molecules accelerate the nonradiative relaxation of the excited fluorophores. Time-resolved optoacoustic and phosphorescence measurements clarified that both intersystem crossing and internal conversion are involved in the nonradiative relaxation processes of DBThD-IA and DBSeD-IA. In addition, DBThD-IA exhibits a 10-fold higher photostability in aqueous solution than the original fluorophore DBD-IA, which allowed us to create a new robust molecular nanogel thermometer for intracellular thermometry.     

Physical State for Nonrelativistic Quantum Electrodynamics

A physical subspace and physical Hilbert space associated with asymptotic fields of nonrelativistic quantum electrodynamics are constructed through the Gupta–Bleuler procedure. Asymptotic completeness is shown and a physical Hamiltonian is defined on the physical Hilbert space.     

Reverse orthogonal strategy for oligosaccharide synthesis

Herein, we report the invention of a novel expeditious concept for oligosaccharide synthesis. Unlike the classic orthogonal strategy based on leaving groups, the reverse approach is based on orthogonal protecting groups, herein p-methoxybenzyl and 4-pentenoyl, which allows for efficient oligosaccharide assembly in the reverse direction.     

Optical and magneto-optical properties in Fe-doped glasses irradiated with femtosecond laser

Optical, magnetic, and magneto-optical properties have been investigated for the α-Fe₂O₃-doped transparent glasses irradiated with an infrared fs laser and subsequently annealed. The values of the saturation magnetization at room temperature for the irradiated glasses were increased compared with the as-prepared samples, which is due to the precipitation of the ferrimagnetic ferrite nanoparticles (NPs). By adding further dopants as precursors of plasmonic metals, Au or Al NPs were space-selectively precipitated together with the ferrite NPs in a confined region after irradiation and thermal annealing. In the case of the glass codoped with Al, magneto-optical Faraday effect was plasmonically enhanced and exhibited a negative distinct peak ascribed to a coupling between the ferrimagnetism of ferrite NPs and the localized surface plasmon resonance of Al NPs, while the glass, in which ferrite and Au NPs were precipitated, showed a positive enhancement of Faraday effect due to a coupling of plasmon resonance with diamagnetism of glass matrix.     

The first total synthesis of ganglioside GalNAc-GD1a, a target molecule for autoantibodies in Guillain-Barré syndrome

The first synthesis of ganglioside GalNAc-GD1a, featuring efficient glycan assembly and a cyclic glucosyl ceramide as a versatile unit for ganglioside synthesis is described. Although ganglioside GalNAc-GD1a was first found as a brain ganglioside, IgG autoantibodies to GalNAc-GD1a were subsequently found to be closely related to a human peripheral-nerve disorder, Guillain-Barré syndrome, which is the commonest cause of acute flaccid paralysis worldwide. In this study, the characteristic hexasaccharide part carrying two sialic acid residues was synthesized efficiently by use of a readily accessible GM2-core unit as a common unit. The potentially difficult coupling of the oligosaccharide and ceramide moieties was carried out by using a cyclic glucosyl ceramide as a coupling partner for the hexasaccharide part, thereby successfully providing the framework of the target compound. Global deprotection delivered the homogenous ganglioside GalNAc-GD1a. An enzyme-linked immunosorbent assay showed that sera from patients with Guillain-Barré syndrome reacted both with natural and with synthetic GalNAc-GD1a.     

Contrast-enhanced MR angiography in rats with hepatobiliary contrast agents

The aim of this animal study was to evaluate the feasibility of contrast-enhanced magnetic resonance (MR) angiography with two hepatobiliary contrast agents, Gd-DTPA-DeA and Gd-EOB-DTPA. Coronal images of the rat abdomen were acquired using a three-dimensional spoiled gradient recalled sequence before and after the administration of Gd-DTPA-DeA, Gd-EOB-DTPA, or Gd-DTPA. Four sets of postcontrast images were collected every 90 s. Contrast ratios were calculated for the abdominal aorta on the source images, and the retention index was defined as the ratio of the contrast ratio on the last imaging to that on the first postcontrast imaging. Partial minimum intensity projection (MIP) images covering the abdominal aorta were generated from the first and second postcontrast imagings, and the image quality was visually evaluated. The contrast ratio on the first postcontrast imaging was the highest for Gd-DTPA-DeA, followed by Gd-EOB-DTPA and Gd-DTPA. Retention indices were higher with Gd-DTPA-DeA than with Gd-EOB-DTPA and Gd-DTPA, implying a prolonged contrast effect with Gd-DTPA-DeA. On the MIP image from the first postcontrast imaging, delineation of the abdominal aorta tended to be better with Gd-DTPA-DeA and Gd-EOB-DTPA than with Gd-DTPA, and the difference was evident at low injection doses. Image quality for the second postcontrast imaging was higher with Gd-DTPA-DeA than with the other two agents, suggesting a longer imaging window for Gd-DTPA-DeA. In conclusion, Gd-DTPA-DeA and Gd-EOB-DTPA showed stronger contrast enhancement for the rat abdominal aorta and provided MR angiograms of higher image quality when compared with Gd-DTPA at the same injection dose. These hepatobiliary agents may make it possible to perform contrast-enhanced MR angiography even at a low injection dose.     

Multiplicity of ground states in quantum field models: applications of asymptotic fields

Ground states of Hamiltonian H of quantum field models are investigated. The infimum of the spectrum of H is in the edge of its essential spectrum. By means of the asymptotic field theory, we give a necessary and sufficient condition for that the expectation value of the number operator of ground states is finite, from which we give an upper bound of the multiplicity of ground states of H. Typical examples are massless GSB models and the Pauli-Fierz model with spin 1/2.