Lipid peroxidation in low density lipoproteins from human plasma and egg yolk promotes accumulation of 1-acyl analogues of platelet-activating factor-like lipids

Oxidative modification of low density lipoprotein (LDL) is known to be a key event for induction of atherosclerosis. However, there has been little progress in structural elucidation of oxidized lipids, especially oxidatively fragmented phospholipids retaining a glycerol backbone. In this study, we found that LDL derived from egg yolk has no platelet-activating factor (PAF) acetylhydrolase activity, and that prolonged incubation of egg yolk LDL with Cu²⁺ resulted in the formation of various PAF-like lipids: 1-acyl type phosphatidylcholines with ansn-2-short-chain dicarboxylate or monocarboxylate group. Only a very small amount of the PAF-like lipid having ansn-2-short-chain monocarboxylate group was detected by gas chromatography-mass spectrometry in Cu²⁺-oxidized LDL from human plasma with high PAF-acetylhydrolase activity, which has been reported to hydrolyze PAF-like lipids to lysophosphatidylcholines. Preincubation of plasma LDL with diisopropyl fluorophosphate dose-dependently inhibited PAF-acetylhydrolase activity, resulting in accumulation of the PAF-like lipids when the LDL was oxidized with Cu²⁺. As well as PAF and lysophosphatidylcholines, several PAF-like lipids were found to inhibit [³H]thymidine incorporation into cultured vascular smooth muscle cells derived from rat aorta. The possible formation of PAF-like lipids by lipid peroxidation in LDL is discussed as well as its possible significance for induction of atherosclerosis.     

Preparation and mechanical properties of polypropylene-clay hybrids using a maleic anhydride-modified polypropylene oligomer

Polypropylene-clay hybrids (PPCH) were prepared using a maleic anhydride-modified PP oligomer (PP-MA) as a compatibilizer. PP was melt-blended with organophilic clay which was intercalated with PP-MA. In these PPCHs, the particles of silicate layers were dispersed at the nanometer level. The particles became smaller and were dispersed more uniformly, as the ratio of PP-MA to the clay was increased. The dynamic storage moduli of the PPCHs were higher than that of PP up to 130°C. For example, the modulus of the PPCH with 5 wt % clay and 22 wt % PP-MA was 1.8 times higher compared to that of PP at 80°C. As the dispersibility of the clays was improved, the reinforcement effect of the clays increased. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 87–92, 1998     

The Functional Diversity of Nitric Oxide Synthase Isoforms in Human Nose and Paranasal Sinuses: Contrasting Pathophysiological Aspects in Nasal Allergy and Chronic Rhinosinusitis

The human paranasal sinuses are the major source of intrinsic nitric oxide (NO) production in the human airway. NO plays several roles in the maintenance of physiological homeostasis and the regulation of airway inflammation through the expression of three NO synthase (NOS) isoforms. Measuring NO levels can contribute to the diagnosis and assessment of allergic rhinitis (AR) and chronic rhinosinusitis (CRS). In symptomatic AR patients, pro-inflammatory cytokines upregulate the expression of inducible NOS (iNOS) in the inferior turbinate. Excessive amounts of NO cause oxidative damage to cellular components, leading to the deposition of cytotoxic substances. CRS phenotype and endotype classifications have provided insights into modern treatment strategies. Analyses of the production of sinus NO and its metabolites revealed pathobiological diversity that can be exploited for useful biomarkers. Measuring nasal NO based on different NOS activities is a potent tool for specific interventions targeting molecular pathways underlying CRS endotype-specific inflammation. We provide a comprehensive review of the functional diversity of NOS isoforms in the human sinonasal system in relation to these two major nasal disorders’ pathologies. The regulatory mechanisms of NOS expression associated with the substrate bioavailability indicate the involvement of both type 1 and type 2 immune responses.     

Synthesis and Characterization of Dialkyl-C61 +

Abstract

Three-step synthesis from dialkyl ketone (R₂C=O) with C₆₀ gave C₆₀(CR₂)_n [R = Me, Et, Pr, Bu, (CH₂)₅.; n = 1, 2]. The adducts were isolated by means of gel permeation chromatography, and the monoadducts were characterized by ¹H and/or ¹³C NMR spectroscopies as a mixture of major [5, 6] and minor [6, 6] isomers. Their solubility and electrochemical properties were reported.

     

R dependence of electronic structure in perovskite type structure compounds, RBRh3 (R: Sc, Y and La)

The electronic structures of perovskite type structure, RBRh₃ (R: Sc, Y and La) were studied by X-ray photoelectron spectroscopy and calculation with full potential linearized augmented plane wave (FLAPW) method. As the lattice constant of the crystals increases with the atomic number of R, it can be discussed how the bond length between boron and rhodium atoms effect on the bonding character. The valence band XPS profiles of the samples are well coincided with the calculated profiles. The calculated electron density maps of the valence bands indicate the following. The charge transfer directions are from R to rhodium atoms and from boron to rhodium atoms. The bonds of RRh and BRh atoms have also covalent character. The covalency of RRh bond increases with the order of the atomic number of R atoms. On the other hand, the covalent bond of BRh decreases with the order atomic number.     

Interaction of nylon 6-clay surface and mechanical properties of nylon 6-clay hybrid

We synthesized nylon 6-clay hybrid materials using four types of clay minerals, montmorillonite, saponite, hectrite, and synthetic mica. The mechanical properties of their injection molded specimens were measured according to ASTM. Nylon 6-clay hybrid using montmorillonite was superior to the other hybrids in mechanical properties. This might result from the difference in the interaction between nylon molecules and silicates in the hybrids. To clarify this hypothesis, we synthesized intercalated compounds of the clay minerals with glycine as the model of the hybrids, and analyzed the interaction using ¹⁵N cross polarization magic angle spinning (CP/MAS) NMR spectroscopy. The ¹⁵N-NMR result reveals that the positive charge density on the nitrogen of the intercalated compound based on montmorillonite was largest in all the intercalated compounds. It was suggested that montmorillonite interacted strongly with nylon 6 by ionic interaction. This ionic interaction was one of the reasons why these hybrid materials had superior mechanical properties. © 1995 John Wiley & Sons, Inc.     

Crystal growth of manganese silicide,MnSi∼1.73 and semiconducting properties of Mn15Si26

Boules of the most silicon-rich silicide of manganese, MnSi_1.73, were grown by the Bridgman method in the composition range from 62.96 to 63.64 at% Si. There are plate-like MnSi precipitates parallel to thec-plane of Mn₁₅Si₂₆ matrix in all boules except at their upper and lower ends. The amount of the MnSi precipitates was about 2 vol%. Measurements of electrical resistivity, Hall coefficient, and thermoelectric power of the boules were made in the temperature range from 77 to 1200 K. Thermoelectronic properties of Mn₁₅Si₂₆ were estimated on the basis of the distribution state of MnSi precipitates in the boule by assuming that metallic MnSi and semiconducting Mn₁₅Si₂₆ alternately crystallized in lamellae. Although the resistivities and thermoelectric powers measured in thec- anda-axis directions of Mn₁₅Si₂₆ showed anisotropy, the former were proportional to exp (4073/T) in the intrinsic region in both directions. The Hall coefficients showed isotropy over the whole temperature range. The degenerate holeconcentration of Mn₁₅Si₂₆ was determined to be 2.1×10²⁷ m^–3. Hall mobilities of Mn₁₅Si₂₆ in both thec- anda-axis directions obey aT ^–3/2-law above 600K. The Hall coefficient calculated from this relationship was in good agreement with the one found for Mn₁₅Si₂₆ in the intrinsic region. The effective-hole masses of Mn₁₅Si₂₆ along thec- anda-axis were found to be, respectively, 15 and 11 times larger than those of a free electron. Assuming that acoustic lattice scattering is dominant and that carriers obey Fermi-Dirac statistics, the temperature dependence of the calculated thermoelectric power was in reasonable agreement with the one estimated for Mn₁₅Si₂₆ in the temperature range from 400 to 1200K.