Radioimmunoassay for platelet-activating factor

A radioimmunoassay (RIA) for measurement of platelet-activating factor (PAF) was developed. At a final antiserum dilution of 1∶640, the lowest detection limit of PAF was 0.1 pmol (50 pg). The standard curve obtained was suitable for measurement of PAF in amounts ranging from 0.1 pmol to 30 pmol. The antiserum showed high specificity. Cross-reaction for lysoPAF, lysophosphatidylcholine and long-chain phosphati-dylcholines was very low (less than 0.025%). 1-Palmitoyl-2-acetyl-sn-glycero-3-phosphocholine cross-reacted slightly (6.25%). PAF exogenously added to macrophage suspensions was quantitatively determined by RIA after solvent extraction and high-performance liquid chromatographic separation. RIA was also used to estimate PAF formation after stimulation of rabbit alveolar macrophages in suspension with calcium ionophore A23187.     

Synthesis of polymers containing acetamide structure and their use as phase transfer catalyst

Summary N-Methyl-N-(p-vinylbenzyl) acetamide was synthesized by the reaction of p-chloromethylstyrene with N-methylacetamide in the presence of sodium hydride. This monomer was readily polymerized or copolymerized with styrene by AIBN. The resulting polymers served as effective phase transfer catalysts for several nucleophilic substitution reactions under liquid-liquid biphase conditions. The catalytic activity was discussed on the terms of cation binding ability of the polymers and activation of anions caused by the desolvation on hydrophobia region of the polymers.     

Graphene's Latest Cousin: Plumbene Epitaxial Growth on a “Nano WaterCube”

While theoretical studies predicted the stability and exotic properties of plumbene, the last group‐14 cousin of graphene, its realization has remained a challenging quest. Here, it is shown with compelling evidence that plumbene is epitaxially grown by segregation on a Pd_1?xPb_x(111) alloy surface. In scanning tunneling microscopy (STM), it exhibits a unique surface morphology resembling the famous Weaire–Phelan bubble structure of the Olympic “WaterCube” in Beijing. The “soap bubbles” of this “Nano WaterCube” are adjustable with their average sizes (in‐between 15 and 80 nm) related to the Pb concentration (x < 0.2) dependence of the lattice parameter of the Pd_1?xPb_x(111) alloy surface. Angle‐resolved core‐level measurements demonstrate that a lead sheet overlays the Pd_1?xPb_x(111) alloy. Atomic‐scale STM images of this Pb sheet show a planar honeycomb structure with a unit cell ranging from 0.48 to 0.49 nm corresponding to that of the standalone 2D topological insulator plumbene.     

Scanning electron microscopy with an ionic liquid reveals the loss of mitotic protrusions of cells during the epithelial-mesenchymal transition

Epithelial-mesenchymal transition (EMT) is a key event in cancer metastasis and is characterized by increase in cell motility, increase in expression of mesenchymal cell markers, loss of proteins from cell-to-cell junction complexes, and changes in cell morphology. Here, the morphological effects of a representative EMT inducer, transforming growth factor (TGF)-β1, were investigated in human lung adenocarcinoma (A549) cells and pancreatic carcinoma (Panc-1) cells. TGF-β1 caused morphological changes characteristic of EMT, and immunostaining showed loss of E-cadherin from cell-to-cell junction complexes in addition to the upregulation of the mesenchymal marker vimentin. During scanning electron microscopy (SEM) with an ionic liquid, we observed EMT-specific morphological changes, including the formation of various cell protrusions. Interestingly, filopodia in mitotic cells were clearly observed by SEM, and the number of these filopodia in TFG-β1-treated mitotic cells was reduced significantly. We conclude that this reduction in such mitotic protrusions is a novel effect of TGF-β1 and may contribute to EMT.     

Formation of diacyl and alkylacyl glycerophosphocholine in rabbit alveolar macrophages

The incorporation of various labeled precursors into alkenylacyl, alkylacyl and diacyl phospholipids in rabbit alveolar macrophages was studied. The incorporation rates of the individual precursors were shown to be quite different among the three subclasses of phospholipids. [³H] Glycerol, [¹⁴C]16∶0, [¹⁴C]18∶1, [¹⁴C]18∶2 and [³²P]-orthophosphate were preferentially incorporated into choline glycerophospholipids (CGP), especially into diacyl glycerophosphocholine (GPC), indicating that the de novo synthesis of diacyl GPC is extremely high. Considerable portions of the radioactiveties of [¹⁴C]16∶0, [¹⁴C]18∶1, [¹⁴C]18∶2 and [³²P] orthophosphate were also found in alkylacyl GPC, the incorporation being higher than or comparable to that in the case of diacyl glycerophosphoethanolamine (GPE). We then examined the activities of cholinephosphotransferase and ethanolaminephosphotransferase, and found that the activity of cholinephosphotransferase was remarkably high in macrophage microsomes compared with that in microsomes from several other tissues. This suggests that diradylglycerols were preferentially utilized by cholinephosphotransferase, which is consistent with the results obtained for intact cells. We confirmed that a considerably higher amount of diacyl GPC as well as alkylacyl GPC was formed through this enzyme reaction with macrophage microsomes than with brain microsomes. The high formation of alkylacyl GPC could be responsible, at least in part, for the accumulation of this unique ether phospholipid, a stored precursor form of plateletactivating factor in macrophages. Fatty chains are designated in terms of number of carbon atoms: number of double bonds, e.g., 18:1 for oleic acid.     

Effect of clofibric acid on the molecular species composition of diacyl glycerophosphocholine of rat liver microsomes

The effect of administeringp-chlorophenoxyisobutyric (clofibric) acid to rats on the molecular species composition of diacyl-glycerophosphocholine (GPC) of rat liver microsomes was studied. Microsomal choline glycerophospholipids were converted to 1,2-diradyl-3-acetylglycerol and were separated into molecular species by reverse-phase high performance liquid chromatography. Diacyl-GPC consisted of 17 different molecular species. The predominant species were arachidonoyl derivatives, such as 18∶0–20∶4 (22.2% of the total) and 16∶0–20∶4 (22.0%). Administration of clofibric acid to rats caused a marked increase in 16∶0–18∶1 species of diacyl-GPC from 8% to 30%, making these the predominant species of diacyl-GPC in clofibric acid-fed rats. Also, a significant decrease (50% of controls) in 18∶0–18∶2 and 18∶0–20∶4 species was observed, whereas the decrease in molecular species containing 16∶0 at the 1-position such as 16∶0–18∶2 and 16∶0–20∶4 was small (approximately 85% of control). The results show that clofibric acid caused marked changes in the molecular species composition of diacyl-GPC. The participation of 1-acyl-GPC acyltransferase and stearoyl-CoA desaturase in the regulation of the molecular species composition of diacyl-GPC is discussed.     

Formation of thin β-FeSi2 template layer for the epitaxial growth of thick film on Si (111) substrate

For the epitaxial growth of thick β-FeSi₂ films, we fabricated ultrathin β-FeSi₂ template layers (thinner than 20 nm) on Si (111) substrates with different methods. Surface morphology and crystallinity of the template layers were found to be dependent on the surface conditions of the substrate and the fabrication method. It was revealed that to form a smooth and continuous template, a hydrogen-terminated surface was better than that covered with a several-nanometer oxide layer. Using this surface, continuous (110)/(101)-oriented epitaxial template was obtained by depositing 6-nm iron at 400 °C and subsequent in situ annealing at 600 °C in MBE chamber, namely, a reaction deposition epitaxy (RDE) method. Co-deposition of iron and silicon with atomic ratio of Fe/Si=1/2 allowed the forming of template layers at further low temperature. Co-deposited template layers exhibited better crystallinity and morphology than those prepared by RDE. By using the optimized template layer, we succeeded in growing high-quality thick β-FeSi₂ films on Si (111) substrates with sharp β-FeSi₂/Si interface.     

Semiconductor-metal phase transition of iron disilicide by laser annealing and its application to form device electrodes

Phase transition of semiconducting β-FeSi₂ to metallic α-FeSi₂ has been realized by laser annealing (Nd:YAG laser, λ=1.064 μm) in order to form ohmic electrodes for β-FeSi₂ devices. The starting samples were 200-nm-thick β-FeSi₂ films formed on Si substrates by reactive deposition epitaxy method. XRD and micro-Raman spectroscopy measurements confirmed the successful phase transition. The electrical resistivity of the α-FeSi₂ film was 2.0×10⁻⁴ Ω·cm, three orders lower than that of the original β-FeSi₂ film (1.4×10⁻¹ Ω·cm). Cross-sectional TEM images and electron diffraction patterns indicated that the upper ∼100 nm of the annealed film was changed to α-FeSi₂ while the lower part remained to be β-FeSi₂. α-FeSi₂ layer had good ohmic contact with β-FeSi₂. A testing p-β-FeSi₂/n-Si diode with laser-annealed α-FeSi₂ as the electrode on β-FeSi₂ showed the same rectifying characteristic as that using Al-evaporated electrode.     

Large‐scale magnetic field analysis by the hybrid finite element‐boundary element method combined with the fast multipole method

This paper describes a large‐scale magnetic field analysis by means of the hybrid finite element‐boundary element (FE‐BE) method. The hybrid FE‐BE method is well‐suited for solving open electromagnetic field problems that comprise movement, nonlinear media, and eddy current. In general, however, large memory and computational costs are required due to the dense blocks in the system matrix generated by the BE part of the hybrid formulation. In order to overcome the above difficulties, we introduce the fast multipole method (FMM) to the hybrid FE‐BE formulation developed by ourselves. Furthermore, we propose a novel preconditioning technique suitable for the hybrid FE‐BE method with the FMM. Some numerical results that demonstrate the effectiveness of the proposed approach are also presented. ©2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 73–80, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20508