Apolipoprotein E polymorphism: Automated determination of apolipoprotein E2, E3, and E4 isoforms

Apolipoprotein E (apo E) plays an essential role in lipoprotein metabolism, where it is involved in the clearance of chylomicrons and very low density lipoproteins. Apart from some rate variants, apo E exists in three common isoforms (E2, E3, and E4). The different isoforms have not only been associated with different plasma lipid levels but have also been correlated with certain pathological conditions, such as lipid disorders (dysbetalipoproteinemia, hypercholesterolemia), cardiovascular diseases, and Alzheimer’s disease. Here we describe a rapid, automated test for the determination of the most frequent polymorphisms (E2, E3, and E4). This polymerase chain reaction-based test allows the reliable discrimination of all six genotypes. The assay has been developed especially for the nonspecialized routine clinical laboratory by employing an analyzer and chemistry often present in this type of laboratory. Because of its low costs and easy handling, the assay can be performed on a daily basis.     

Convenient and efficient syntheses of 4-hydroxy-2(E)-nonenal and 4-oxo-2(E)-nonenal

Lipid peroxidation products 4-hydroxy-2(E)-nonenal (HNE) and 4-oxo-2(E)-nonenal (ONE) were conveniently synthesized using Wittig and Horner-Wardsworth-Emmons (HWE) reaction. Wittig or HWE reaction between an easily prepared phosphorane or phosphonate with glyoxal dimethyl acetal gave a protected 4-oxo-2(E)-nonenal. Hydrolysis gave 4-oxo-2(E)-nonenal, whereas reduction followed by hydrolysis gave 4-hydroxy-2(E)-nonenal.     

Cholesterol secretion from hepatocytes induced by triacylglycerol and apolipoprotein E

The mechanism for the increase in plasma cholesterol levels in cholesterol-fed rats following chylomicron transport was investigated in intact animals, in isolated perfused liver, and in hepatocytes in monolayer cultures. Intravenous administration of egg phosphatidylcholine in amounts greater than those required to cause a plasma cholesterol response when given as chylomicrons was without effect. This makes it unlikely that increased plasma cholesterol levels resulted from the recruitment of tissue cholesterol by the plasma chylomicron phospholipids that persisted in the plasma after triacylglycerol clearance. The hepatic origin of the increased plasma cholesterol levels was directly confirmed by two hepatic perfusion experiments. When cholesterol-fed rats received intravenous chylomicrons prior to isolated hepatic perfusion, more cholesterol was secreted by the liver than when the rats were injected intravenously with buffer. Perfusion of apolipoprotein E (apo E)-rich triacylglycerol emulsions through the livers also enhanced cholesterol secretion. The increase in hepatocyte cholesterol secretion seen with cholesterol-fed rats was also noted in monolayer cultures following incubation with apo E rich-triacylglycerol emulsions. The apolipoprotein or the emulsion alone, or apo E-rich phosphatidylcholine liposomes, had no effect. The data confirm previous indirect observations that the liver is the source of cholesterol that appears in plasma following transport of chylomicrons or following a lipid-rich meal in cholesterol-fed rats. The data also re-emphasize the importance of providing apo E with triacylglycerol emulsions to initiate secretion of lower density lipoproteins by the liver.     

ZIF-8/乙二醇-水浆液吸收-吸附CH4/H2和CH4/N2

为了有效地捕集焦炉气及煤层气中的甲烷,提出了一种新型捕集技术:吸收-吸附组合方法,该方法通过把ZIF-8分散到乙二醇水溶液中形成悬浮浆液,实现对甲烷组分的捕集。首先测定了甲烷、氮气和氢气在浆液中的吸收-吸附容量,得出吸着量大小的顺序为CH₄> N₂> H₂,然后对CH₄/H₂和CH₄/N₂的混合气进行吸着平衡研究,发现浆液均能有选择性地吸着甲烷。对浆液中回收的ZIF-8材料进行XRD表征,分析证明在整个吸着过程中ZIF-8结构没有发生变化并且ZIF-8/乙二醇-水浆液能重复利用。     

Associations between apolipoprotein E genotype and circulating F<Subscript>2</Subscript>-isoprostane levels in humans

Apolipoprotein E (apoE), an important determinant of plasma lipoprotein metabolism, has three common alleles (ε2, ε3, and ε4). Population studies have shown that the risk of diseases characterized by oxidative damage, such as coronary heart disease and Alzheimer’s disease, is significantly higher in ɛ4 carriers. We evaluated the association between apoE genotypes and plasma F₂-isoprostane levels, an index of lipid peroxidation, in humans. Two hundred seventy-four healthy subjects (104 males, 170 females; 46.9±13.0 yr; 200 whites, 74 blacks; 81 nonsmokers, 64 passive smokers, and 129 active smokers) recruited for a randomized clinical antioxidant intervention trial were included in this analysis. ApoE genotype was determined by PCR and restriction enzyme digestion. Free plasma F₂-isoprostane was measured by GC-MS. Genotype groups were compared using multiple regression analysis with adjustment for sex, age, race, smoking status, body mass index, plasma ascorbic acid, and β-carotene. Subjects with ε3/ε4 and ε4/ε4 genotype (ε4-carriers) and with ε2/ε3 and ε3/ε3 (non-ε4-carriers) were pooled for analysis. In subjects with high cholesterol levels (total cholesterol above 200 mg/dl), plasma F₂-isoprostane levels were 29% higher in ε4 carriers than in non-ε4-carriers (P=0.0056). High-cholesterol subjects that are ε4 carriers have significantly higher levels of lipid peroxidation as assessed by circulating F₂-isoprostane levels.     

一维直孔道MOFs对CH4/N2和CO2/CH4的分离

非常规天然气未来可以作为常规天然气的有效补充,其中低浓度煤层气和生物质燃气分别需要脱除大量的N₂ 和CO₂以达到富集和纯化CH₄的目的。本研究针对CH₄/N₂这一对较难分离的气体组合,选取了具有一维菱形孔道的MOFs材料Cu(INA)₂作为吸附剂,将合成的样品做了XRD和TG表征,测试了纯气体CO₂、CH₄和N₂的吸附曲线,利用巨正则系综蒙特卡罗(GCMC)分子模拟和理想吸附溶液理论(IAST)计算了气体的吸附热和该材料对于CH₄/N₂和CO₂/CH₄的吸附选择性系数;3 MPa压力下制备的颗粒样品填装吸附分离装置,进行了混合气体CH₄/N₂ (50%/50%)和CO₂/CH₄ (50%/50%)的穿透试验,分离的结果显示,Cu(INA)₂不仅高选择性地吸附CH₄/N₂混合物中的CH₄(S_CH4/N2=10),而且对CH₄/N₂的分离效果优于CO₂/CH₄。     

Low-temperature catalytic combustion on Pt/SO 4 2− /ZrO2 and Pd/SO 4 2− /ZrO2 catalysts

Low-temperature combustion of various organic compounds on Pt/SO ₄ ^–2 /ZrO₂ and Pd/SO ₄ ^–2 /ZrO₂ was studied. For these organic compounds, especially saturated hydrocarbons, the combustion activities of Pt/SO ₄ ^–2 /ZrO₂ are higher than those of Pt/ Al₂O₃. Pt/SO ₄ ^–2 /ZrO₂ combustion catalysts can be used in a wide range of space velocity and oxygen content. The catalytic activity is enhanced with an increase of Pt loading from 0.1 to 1.0 wt%. The superacidity of the support material is responsible for the improvement in activity rather than an increase in catalyst surface area or metal dispersion. Pd/SO ₄ ^–2 /ZrO₂ are less active than Pt/SO ₄ ^–2 /ZrO₂.     

Microsequencing of bovine cerebrospinal fluid apolipoproteins: Identification of bovine apolipoprotein E

In studies of bovine plasma lipoproteins, apolipoprotein E (apoE) was not found associated with α-lipoproteins isolated over a broad range of densities. However, studies of cerebrospinal fluid (CSF) lipoproteins from other mammals have shown that apoE is a major apolipoprotein associated with high density lipoprotein, a fact that prompted us to determine if this were also the case in bovine CSF. CSF samples were obtained from animals with a surgically implanted catheter. Most analyzed samples were obtained from cows at various stages of the postpartum period; however, a few samples also were obtained at term or during pregnancy. Analyses of isolated ultracentrifugal fractions by polyacrylamide gel electrophoresis revealed the presence of two apo, with the expected molecular weights for apoE and apoA-I. By using both matrix-assisted laser desorption mass spectrometry and microsequencing techniques, we demonstrated that these apo are indeed apoE and apoA-I.     

(NH4)2SO4和Na2SO4混合溶液中(NH4)2SO4结晶动力学及铁/铝/锰/铬等离子对(NH4)2SO4结晶的影响规律

湿法冶金、三元前体制备等过程均会产生含硫酸钠与硫酸铵的高盐废水。研究高盐废水中硫酸铵的结晶动力学,并考察常见金属离子的影响规律对高盐废水处理具有重要意义。本文以含硫酸钠与硫酸铵混合溶液中硫酸铵的结晶过程为例,系统考察了硫酸铵的结晶动力学及铁、铝、锰、铬对硫酸铵结晶的影响规律。含硫酸钠与硫酸铵混合溶液硫酸铵结晶动力学研究结果表明,硫酸铵生长速率和成核速率方程分别为为B=1.303×10^-16G^1.069M_T^1.801,G=15.708σ^1.387;在硫酸钠与硫酸铵混合体系中,溶液过饱和度影响硫酸铵成核及生长速率,溶液过饱和度减小,晶体的成核及生长速率都会减小,与单体系硫酸铵结晶动力学结果相比,动力学参数均有所下降。铁、铝、锰、铬对硫酸铵结晶的影响规律研究结果表明,铁、铝抑制了硫酸铵晶面生长,结晶粒度减小;锰、铬对硫酸铵结晶有一定的促进作用,结晶粒度增大。金属离子改变了硫酸铵晶习,锰使结晶呈现三棱柱状,铁、铝使硫酸铵结晶片状生长。不同金属离子条件下的结晶动力学方程表明,铁和铝对结晶...     

An Intermediate-temperature H2S Fuel Cell with a Li2SO4-based Proton-conducting Membrane

A laboratory-scale intermediate-temperature H2S fuel cell with a configuration of H2S, （metal sulfide-based composite anode）/Li2SO4＋Al2O3/（NiO-based composite cathode）, air was developed and studied for production of power and for desulfurization of a fuel gas process stream. The cell was run at typical temperature （600-650℃） and ambient pressure, but its electrochemical performance may be limited by electrolyte membrane thickness. The membrane and its performance in cell have been characterized using scanning electron microscope （SEM） and electrochemical impedance spectrum （EIS） techniques. Composite anodes based on metal sulfides, Ag powder and electrolyte behaved well and stably in H2S stream, and composite cathodes based mainly on nickel oxide, Ag powder and electrolyte had superior performance to Pt catalyst. The maximum power density of up to 70mW.cm^-2 and current density of as high as 250mA.cm^-2 were obtained at 650℃. However, the long-term cell stability remains to be investigated.     

Solid Solubility and Polymorphism in the System Sr2SiO4-Sr2GeO4-Ba2GeO4-Ba2SiO4

The reciprocal salt pair Sr₂SiO₄-Sr₂GeO₄-Ba₂GeO₄-Ba₂SiO₄ was investigated using X-ray powder diffraction and DTA. Unlimited solubility in the low-K₂SO₄ structure type (α') occurs throughout the system above 85°C. The nonlinear changes of some lattice constants of the solid solutions are discussed. A stable monoclinic low-temperature (β) form of Sr₂SiO₄ was found which converts reversibly to the high-temperature α'-modification at 85°C. The enthalpy of the β-α' transition is 51 cal/mol. In the reciprocal salt pair the β-form solid solutions occur in a very narrow region below 85°C.     

Boosting selective C2H2/CH4, C2H4/CH4 and CO2/CH4 adsorption performance via 1,2,3-triazole functionalized triazine-based porous organic polymers

Nitrogen-rich porous organic polymers have shown great potentials in gas adsorption/separation, photocatalysis, electrochemistry, sensing and so on. Herein, 1,2,3-triazole functionalized triazine-based porous organic polymers (TT-POPs) have been synthesized by the copper-catalyzed azide-alkyne cycloaddition (Cu-AAC) polymerization reactions of 1,3,5-tris(4-azidophenyl)-triazine with 1,4-diacetylene benzene and 1,3,5-triacetylenebenzene, respectively. The characterizations of N₂ adsorption at 77 K show TT-POPs possess permanent porosity with BET surface areas of 666 m²·g^-1 (TT-POP-1) and 406 m²·g^-1 (TT-POP-2). The adsorption capacities of TT-POPs for CO₂, CH₄, C₂H₂ and C₂H₄, as well as the selective separation abilities of CO₂/N₂, CO₂/CH₄, C₂H₂/CH₄ and C₂H₄/CH₄ were evaluated. The gas selective separation ratio of TT-POPs was calculated by the ideal adsorbed solution theory (IAST) method, wherein the selective separation ratios of C₂H₂/CH₄ and C₂H₄/CH₄ of TT-POP-2 was 48.4 and 13.6 (298 K, 0.1 MPa), which is comparable to other adsorbents (5.6-120.6 for C₂H₂/CH₄, 10-26 for C₂H₄/CH₄). This work shows that the 1,2,3-triazole functionalized triazine-based porous organic polymer has a good application prospect in natural gas purification.     

Pro/E技术讲座(四)Pro/E模具设计基础

本文在上期了解模具设计入门知识的基础上，以1个手柄模具为实例，详细地介绍了使用Pro／MOLDESIGN软件进行模具设计的过程，包括从模型建立、工作目录设置、文件建立、模板选择、参照模型加入到工件建立的全过程，最后重点介绍了一下模具收缩率的设置及计算方法以及在计算的过程中可能碰到和需要注意的几个问题。     

A facile synthesis of 4-hydroxy-2(E)-nonenal

A facile, efficient synthesis of 4-hydroxy-2(E)-nonenal is presented as an alternative to the approaches published previously, which either employed four to six separate steps or furnished low yields. The commercially available 3(Z)-nonenol was sequentially oxidized into 3,4-epoxynonanol by 3-chloroperoxybenzoic acid followed by oxidation of the alcohol by periodinane to afford 4-hydroxy-2(E)-nonenal by this two-step procedure in 48±7% yield.     

2-烷硫基-4H-咪唑啉-4-酮杀菌剂的有效合成方法

用2-硫代-3-正丁基-5-苯基亚甲基-4-咪唑啉二酮(1)的S-烷基化反应合成了新型2-烷硫基-3-正丁基-5-苯基亚甲基-4H-咪唑啉-4-酮衍生物(2)。对影响S-烷基化反应的条件进行了优化,优化条件如下:2-硫代-4-咪唑啉二酮5mmol、卤代烷6mmol和无水碳酸钾8mmol;反应温度50°C或室温;反应时间2～3h。优化条件下2a～2e的收率为43%～81%。探讨了所合成化合物的波谱性质,其结构经元素分析、IR、1HNMR和MS确证。     

The comparison of mechanical behavior of MgO-MgAl2O4 with MgO-ZrO2 and MgO-MgAl2O4-ZrSiO4 composite refractories

Mechanical properties of different compositions obtained from the additions of 5, 10, 20 and 30 wt.% zircon (ZrSiO₄) into the MgO-spinel composite refractories and ZrO₂ into MgO have been examined, the variations that occurred have been determined, and the parameters affecting those factors have been investigated with the reasons. The density, strength, Young's modulus, fracture toughness, fracture surface energy and work of fracture were measured and evaluated. Microstructural variations and fracture surfaces have been examined and the formation of new phases has been identified depending on the additive type and quantity. The relationships between mechanical properties and structural variations for different compositions have been examined. In MgO-spinel materials, strength, Young's modulus and fracture toughness values decrease up to 20% spinel addition and stay almost constant for further loads. ZrO₂ addition displays same trend but not as effective as spinel. Besides, since ZrO₂ is stable in cubic form, it does not show any toughening mechanism. Forsterite formation is the most important factor for 2-fold improvement in the mechanical properties of MgO-spinel-zircon refractories. The more the zircon addition, the more the mechanical properties improve. The generation of natural bonding between matrix particles with forsterite formation, on the other hand, causes the fracture path to turn to transgranular fracture with an increase in fracture surface energy and a decrease in work of fracture, among which the latter is considered as an indicator of thermal shock resistance of the materials being high.     

Structural characterization by computer experiments of the lipid-free LDL-receptor-binding domain of apolipoprotein E

The structure and dynamics of the lipid-free LDL-receptor-bindingdomain of apolipoprotein E (apoE-RBD) has been investigatedby Molecular Dynamics Simulations. ApoE-RBD in its monomericlipid-free form is a singular four-helix bundle made up of fourelongated amphipathic helices. Analysis of one 1.5 ns moleculardynamics trajectory of apoE-RBD performed in water indicatesthat the lipid-free domain adopts a structure that exhibitscharacteristics found in native proteins: it has very stablehelices and presents a compact structure. Yet its interior exhibitsa larger number of transient atomic-size cavities relative tothat found in other proteins of similar size and its apolarside chains are more mobile. The latter features distinguishthe elongated four-helix bundle as a slightly disordered structure,which shows a structural likeness with some de novo designedfour-helix bundle proteins and shares with the latter a leucine-richresidue composition. We anticipate that these unique propertiescompared with other native helix bundles may be related to thepostulated ability of apoE-RBD to undergo an opening of itsbundle upon interaction with phospholipids. The distributionof empty cavities computed along the trajectory in the interfaceregions between the different pairs of helices reveals thatthe tertiary contacts in one of the interfaces are weaker suggestingthat this particular interface could be more easily rupturedupon lipid association.     

Modification of SO4 2--ZrO2 and Pt/SO4 2--ZrO2 properties during n-hexane isomerization

The modification of the textural properties and crystalline structure of SO₄ ^2--ZrO₂ and Pt/SO₄ ^2--ZrO₂ during n-hexane reaction at 473 K and 6 kg cm^-2 has been studied in the presence of either hydrogen or nitrogen. Sulfur content before and after reaction and the amount of coke at the end of the reaction were measured. The coke deposited on the catalysts blocks the pores of small size and decreases the surface area of the used catalysts. After regeneration, surface area is not completely restored. The loss of sulfur during reaction, probably associated to the reaction medium, also produces a decrease in surface area by the collapse of the smallest pores which generates larger ones. The transformation of tetragonal to monoclinic crystalline structure of zirconia begins to occur when sulfur content drops below a critical value. This revised version was published online in July 2006 with corrections to the Cover Date.     

Membranes for CO2 /CH4 and CO2/N2 Gas Separation

Membrane technology has emerged as a leading tool worldwide for effective CO₂ separation because of its well-known advantages, including high surface area, compact design, ease of maintenance, environmentally friendly nature, and cost-effectiveness. Polymeric and inorganic membranes are generally utilized for the separation of gas mixtures. The mixed-matrix membrane (MMM) utilizes the advantages of both polymeric and inorganic membranes to surpass the trade-off limits. The high permeability and selectivity of MMMs by incorporating different types of fillers exhibit the best performance for CO₂ separation from natural gas and other flue gases. The recent progress made in the field of MMMs having different types of fillers is emphasized. Specifically, CO₂/CH₄ and CO₂/N₂ separation from various types of MMMs are comprehensively reviewed that are closely relevant to natural gas purification and compositional flue gas treatment