ジステアロイル-N-モノメトキシ-ポリエチレングリコール-スクシニル-フォスファチジルエタノールアミン (PEG-), (PEG-のPEG平均分子量は1000, 2000, 3000, 5000および12000) のPEG鎖長がリポソームの巨視的状態に及ぼす影響を, リポソーム形成, 粒子径, 表面電位および分散性の観点から検討した。調整に用いたジパルミトイルフォスファチジルコリン (DPPC) の量は全てリポソームの形成に使われたが, 長いPEG鎖をもつPEG-の場合には用いた全ての量がリポソーム形成に使われるのではなかった。リポソーム二分子膜中のPEG-の濃度は, PEG-のPEG鎖長の増加に伴い減少した。PEG-を含むリポソームの粒子径は, PEG-のPEG鎖長の増加に伴い減少した (PEG12000-を除く) 。PEG12000-の場合には, DPPCリポソーム表面に吸着しているようであった。リポソームのゼータ電位の負の絶対値は, PEG-のPEG鎖長の増加に伴い減少した。PEG-を含むリポソームの分散性は, ゼータ電位の絶対値の減少にもかかわらず, 少なくとも14日間は保持されていた。

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Lecithin is known to undergo heat induced deterioration by the Maillard reaction between 1 mol of any sugar, except 2-deoxy sugar, and 2 mol of phosphatidylethanolamine (PE). However, we have previously reported that adding fatty acid metal salts can inhibit heat deterioration of soybean lecithin (SL). To clarify the mechanism of inhibition, 1,2-di-O-stearoyl-sn-glycero-3-phosphatidylethanolamine (

), d-glucose, and calcium stearate or calcium decanoate were heated in octane. When and d-glucose with calcium stearate or calcium decanoate were heated in the octane, the heat deterioration of was significantly inhibited, and no increase in UV absorption at 350 nm was observed. From these reactant solutions, one compound having a phosphate group and no primary amine was isolated, and NMR spectra confirmed that two molar of stearic acid derived from were coordinated to the amino group and phosphate group of . Therefore, we concluded that adding fatty acid metal salts reduced the nucleophilic reactivity of the amino group of PE and inhibited the Maillard reaction with sugars because two molar of fatty acid derived from PE coordinated to the amino group and phosphate group of PE.

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NOF manufactures and supplies highly purified phospholipid derivatives suitable for liposome formulations which are extensively used for pharmaceuticals. And we has provided novel phospholipid derivatives, ‘SUNBRIGHT® -PG8’ series. Use of these lipids enables researchers to obtain highly pH-sensitive carriers for efficient cytoplasmic delivery of bioactive molecules. As the example of carriers, we designed pH-sensitive liposomes. These liposomes were stable at physiological pH, but became destabilized and fusogenic significantly responding sharply to very small pH change in weakly acidic pH region. They delivered their contents (pyranine) into cytosol of dendritic cell-derived DC2.4 cells. When these pH-sensitive liposomes loaded with antigenic protein ovalbumin (OVA) were subcutaneously administered to mice, the antigen-specific cellular immunity was efficiently induced in the mice.

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The problem of estimating the nominal angles and angular spreads of multiple coherently distributed (CD) sources in a symmetric uniform linear array (ULA) is considered. Based on structure of the subarrays consisting of two opposite sensors relative to the center of a ULA and the rank reduction (RARE) concept, the proposed algorithm is able to estimate the nominal angles without any angular signal density model assumptions of the sources. Using the estimated nominal angles, the angular spread of each source is then obtained using a one-dimensional (1-D) distributed source parameter estimator ().

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Poly(ethylene glycol)-grafted liposomes (PEG-liposomes) were prepared from dipalmitoylphosphatidylcholine (DPPC) with various amounts of distearoyl-N-monomethoxy poly(ethylene glycol)-succinyl-phosphatidylethanolamines (-PEG) with PEG molecular weights of 1000, 2000, 3000 and 5000. The effects of -PEG concentration on the permeability of PEG-liposomes were investigated using carboxyfluorescein (CF). In the gel state, the CF leakage from PEG-liposomes was decreased with increasing mole fractions of -PEG for all PEG molecular weights. In the liquid-crystalline state, the CF leakage from PEG-liposomes containing -PEG1000 gradually increased with increasing mole fractions of -PEG, while that of PEG-liposomes whose molecular weight in PEG units was above 2000 rapidly decreased by the addition of -PEG. Furthermore, no effect of PEG molecular weight on CF leakage was observed. The relationship between the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) (or 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH)) and the mole fraction of -PEG for PEG-liposomes was also investigated. No significant changes in fluorescence polarization of DPH for liposomal bilayer membranes was observed in the gel and liquid-crystalline states due to the addition of -PEG, while that of TMA-DPH was decreased compared with that of liposomes without -PEG in both states.

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The in vivo distribution of antitumor drugs is usually lack of selectivity, and thus, leading to a low efficacy of chemotherapy on cancers and high toxicity to normal cells. Receptor-mediated targeting liposome with pH-sensitivity as a dual drug delivery system is one of the efficient approaches to overcome the disadvantages. The study was to synthesize a novel smart polymeric material (folate-poly(2-ethyl-2-oxazoline)-distearoyl phosphatidyl ethanolamine, F-PEOz-), which can combine with the folate-receptor (FR) over-expressed on cancer cells and respond to pH changes in endosome–lysosome system in cancer cells to rapidly release drug simultaneously. The F-PEOz- was synthesized by the method of asymmetric synthesis of organic polymer and characterized by IR, ¹H-NMR, electrospray ionization (ESI)-MS and gel permeation chromatography (GPC). To investigate the properties of targeting and pH-sensitivity of F-PEOz-, blank liposomes, blank fluorescently labeled liposomes and doxorubicin (DOX)-loaded liposomes containing F-PEOz- or PEOz- or were prepared. The cytotoxicity, cellular uptake and drug cumulative release in vitro were investigated. Blank liposomes modified with PEOz block had little cytotoxicity in vitro. The liposomes containing F-PEOz- showed a higher affinity to human ovarian cancer cell SKOV3, a FR⁺ cancer cells, than those with PEOz-. A higher drug cumulative release from DOX-loaded liposomes containing F-PEOz- or PEOz- in vitro was found in phosphate buffered saline at pH 5.0 medium than at pH 7.4. These results indicate that F-PEOz- exhibits selective targeting, pH-sensitivity and little cytotoxicity, and may be a promising polymeric material for dual receptor and pH-sensitive targeting liposome.

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ジステアロイル-N-モノメトキシ-ポリエチレングリコールースクシニル-フォスファチジルエタノールアミン (PEG-) を含むジパルミトイルフォスファチジルコリン (DPPC) リポソームのフリーズフラクチャー法による電顕写真を撮影した。DPPC二分子膜の主相転移温度と前転移温度の間の温度から急速凍結させた上記リポソームの割断面には帯状構造の他に平面構造も存在していたことからリポソーム内での相分離が示唆された。

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Novel four 2,3-dihydro-1H-imidazo[1,2-a]pyridine-4-ylium derivatives were obtained with increase of UV absorption at 350 nm and browning of the solution by heating paste lecithin from soybean (SL) in octane. These four derivatives were formed by reaction of one molar of any sugar except 2-deoxysugars with two molar of phosphatidylethanolamines (PE) in SL. To confirm the reaction mechanism, several ¹³C-labeled-sugars were reacted with 1,2-di-O-stearoyl-sn-glycero-3-phosphatidylethanolamine (), respectively. These reactants clearly showed that five carbons of the pyridinium ring and one carbon of the substituted group were based on those of a sugar and that the formation of the pyridinium derivatives was accompanied with cleaving between the carbons of 1- and 2-positions in the sugar and rearrangement. This reaction is a new rearrangement reaction and we named it “new pseudo Maillard rearrangement reaction”.

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The effect in mice of the molecular weight of polyethyleneglycol on prolonging the circulation time of large unilamellar liposomes (LUVs) was examined using four different distearoyl N-(monomethoxy polyethyleneglycol succinyl) phosphatidylethanolamines (-PEGs). The molecular weights tested were 1000, 2000, 5000 and 12000. Incorporation of 6 mol% of -PEG in LUV composed of distearoylphosphatidylcholine (DSPG) / cholesterol (CH) (1 : 1 in molar ratio) increased the blood circulation half-life significantly more than those without -PEG derivatives. -PEGs with molecular weights of 1000 and 2000 prolonged the circulation time of liposomes more than other -PEGs wiht higher molecular weights, such as 5000 and 12000. Their effects are also higher than ganglioside GM1, a well described glycolipid with this effect. DSPC/CH LUV-incorporated -PEG with a molecular weight of 2000 displayed a high concentration in the blood, approximately 40% of the dose, 6 h after the injection.

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Post-insertion method is now widely used to modify liposomes with poly(ethylene glycol) (PEG) lipids. In this study, we examined the physicochemical properties of surface layers of distearoylphosphatidylethanolamine- PEG2000-modified liposomes composed of distearoylphosphatidylcoline, distearoylphosphatidylglycerol and cholesterol prepared in post-insertion method. Zeta potential measurements showed that the estimated aqueous layer thickness of PEG liposomes increases with increasing concentrations of PEG lipids added. Size exclusion chromatography demonstrated that the incorporation efficiency of PEG lipids into liposomes gradually decreases with increasing addition amount of PEG lipids. Quenching experiments of fluorescence-labeled PEG lipids confirmed that almost all PEG lipids distribute at the outermost layer of liposomes in the post-insertion preparation whereas PEG lipids distribute equally at inner and outer layers of liposomes in the conventional pre-mixed method. By correcting the incorporation efficiency and the outermost distribution of PEG lipids in liposomes, we found that the dependency of increases in aqueous layer thickness of PEG liposomes upon the outermost content of PEG lipids is similar in the both post-insertion and pre-mixed methods. Fluorescence resonance energy transfer measurements suggested that the increasing behavior of aqueous layer thickness is closely correlated with the conformational transition of PEG chains at the liposome surface. These results provide comparative information of the surface properties of PEG-modified liposomes prepared by the post-insertion and pre-mixed methods.

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The effects of poly(ethylene glycol) (PEG) chain length of PEG-lipid on the membrane characteristics of liposomes were investigated by differential scanning calorimetry (DSC), freeze-fracture electron microscopy (FFEM), fluorescence polarization measurement and permeability measurement using carboxyfluorescein (CF). PEG-liposomes were prepared from mixtures of dipalmitoyl phosphatidylcholine (DPPC) and distearoyl phosphatidylethanolamines with covalently attached PEG molecular weights of 1000, 2000, 3000 and 5000 (-PEG). DSC and FFEM results showed that the addition of -PEG to DPPC in the preparation of liposomes caused the lateral phase separation both in the gel and liquid-crystalline states. The fluidity in the hydrocarbon region of liposomal bilayer membranes was not significantly changed by the addition of -PEG, while that in the interfacial region was markedly increased. From these results, it was anticipated that the CF leakage from PEG-liposomes is accelerated compared with DPPC liposomes. However, CF leakage from liposomes containing -PEG with a 0.060 mol fraction was depressed compared with regular liposomes, and the leakage decreased with increasing PEG chain length. Furthermore, the CF leakage from liposomes containing -PEG with a 0.145 mol fraction was slightly increased compared with that of liposomes containing -PEG with a 0.060 mol fraction. It is suggested that the solute permeability from the PEG-liposomes was affected by not only properties of the liposomal bilayer membranes such as phase transition temperature, phase separation and membrane fluidity, but also the PEG chain of the liposomal surface.

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In this paper, a new parameter estimator for coherently distributed (CD) noncircular (NC) signals is proposed, and can estimate both the central direction-of-arrivals (DOAs) and the angular spreads. It can also be considered as an extended version of the generalized Capon method by using both covariance matrix and an elliptic covariance matrix. The central DOAs and angular spreads are obtained by two-dimensional spectrum-peak searching. Numerical examples illustrate that the proposed method can estimate the central DOAs and the angular spreads when the number of signals is greater than the number of sensors. The proposed method also offers better performance than the methods against which it is compared.

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Long-circulating thermosensitive liposomes with hyperosmotic internal aqueous phase intended for the delivery of macromolecules were prepared and characterized in vitro. Higher osmotic pressure markedly increased the release of macromolecules such as dextran. This effect was pronounced with liposome containing amphipathic polyethyleneglycol. The release of dextran was also influenced by the concentration of amphipathic polyethyleneglycol added to the liposomes. These results indicate that higher internal osmotic pressure and amphipathic polyethyleneglycol content contributes to the in vitro temperature-dependent release of the macromolecule dextran.

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工作物クランプの締付不良は加工不良に繋がるため，加工前に締付不良を検出することが求められる．工作物の周波数応答を簡便に得るために，圧電素子を用いた加振と変位測定の両方を行える装置を開発した．この装置を用いて，締付不良時と正常締付時の周波数応答の差を用いて工作物クランプの締付不良を検出できるかを調査した．その結果，クランプ付近で測定すると周波数応答に明確な差が生じ，クランプ不良を検出できた．

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Although the concept of a drug delivery system (DDS) is usually applied to conventional drug therapy, it is also important for cell-based therapy. The surface manipulation of living cells represents a powerful tool for controlling cell behaviors in the body, such as enhancement of cell-cell interactions, targeted delivery of cells, and protection from immunological rejection. Functional groups, including amines, thiols, and carbonyls, offer excellent opportunities for chemical modification through the formation of covalent bonds with exogenous molecules. Non-natural reactive groups introduced by metabolic labeling were recently utilized for targeted chemical modification. On the other hand, noncovalent strategies are also available; two major examples are electrostatic interaction with a negative charge on the cell surface and hydrophobic insertion or interaction with the cell membrane. In this study, we analyzed factors affecting cell surface modifications using PEG-lipid and succeeded in enhancing the efficacy of modification by cyclodextrin. Then, mesenchymal stem cells (MSCs), whose therapeutic effect has been demonstrated at the clinical stage and which have been clinically used as a drug, were decorated with PEG-lipid conjugates having a targeted ligand such as peptide or scFv, which are recognized by ICAM1. The peptide or scFv decoration enhanced the cell adhesion of MSCs on cytokine treated-endothelial cells. This technique will prompt the targeted delivery of MSCs to intended therapy sites, and underscores the promise of cell surface engineering as a tool for improving cell-based therapy.

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Artificial introduction of functional molecules on the cell surface may be a promising way to improve the therapeutic effects of cell therapy. Pegylated lipids are conventionally used in drug carriers. The lipid part of pegylated lipids noncovalently interacts with the cell surface. However, little information is available regarding conditions for cell-surface modification by using pegylated lipids. In this study, we synthesized fluorescein-labeled pegylated lipids and evaluated the factors that affect modification efficiency by using human mesenchymal stem cells (hMSCs). As the concentration of the pegylated lipid as well as the exposure time increased, the modification efficiency increased. The modification efficiency at 37°C was 20- and 3-fold higher than that at 4°C and 25°C, respectively. In addition, with an increase in the molecular weight of polyethylene glycol (PEG), more pegylated lipids were extracellularly distributed than those intracellularly distributed. At the optimal condition, pegylated lipids were observed mainly on the cell membrane by confocal microscopy. In contrast, the cell condition (adherent or nonadherent) had little or no effect on the cell-surface modification efficiency. The results of this study will be useful for constructing an optimal modification method for introducing functional molecules on the cell surface.

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In this study, micelles prepared from distearoylphosphatidylethanolamine with covalently attached poly(ethylene) glycol) (PEG) of molecular weight 2000 (-PEG-2000) were employed in micellar electrokinetic chromatography (MEKC) as pseudostationary phases. Since -PEG-2000 contains long hydrophobic alkyl chains, an anionic phosphate group, and hydrophilic PEG chains, the prepared micelles are expected to provide a characteristic retention behavior for both neutral and ionic compounds. As a typical example, a baseline separation of phenol and 2-naphthol was successfully achieved by using the -PEG-2000 micelles as a background electrolyte for MEKC; such success clearly shows that the micelles can retain electrically neutral compounds. The MEKC separations of anionic and cationic compounds with a -PEG-2000 micellar solution and the enantioseparation of binaphthyl compounds with mixed micelles containing bile salt are also discussed.

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Novel four 2,3-dihydro-1H-imidazo[1,2-a]pyridine-4-ylium derivatives were obtained with increase of UV absorption at 350 nm and browning of the solution by heating paste lecithin from soybean (SL) in octane. These four derivatives were characterized the factor based on UV absorption at 350 nm. The SL was separated into the hexane (DSSL fr.) and 60% ethanol in water frs. by liquid- liquid partition method. Even when the DSSL fr. was heated in octane more than 9 h, the four derivatives were not formed and increase of any UV absorption was also not observed but the solution color was slightly yellowing. On the other hand, the formation of four derivatives and increase of UV absorption at 350 nm were observed when DSSL and 60% ethanol in water frs. were combined and, then, heated in octane. From the 60% ethanol in water fr, sucrose, raffinose and stachyose were isolated and identified as compounds which involved the formation of the derivatives with the DSSL fr. When (1,2-di-O-stearoyl-sn-glycero-3-phosphatidylethanolamine) and any hexose were combined and then heated, two 2,3-dihydro-1H-imidazo[1,2-a]pyridine-4-ylium derivatives generated with increase of UV absorption at 350 nm and browning. From these results, it is concluded that the formation of derivatives, with increase of the UV absorption at 350 nm and browning, are based on the reaction of sugars and phosphatidylethanolamine (PE) in SL.

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