氧化型低密度脂蛋白的内皮损伤作用及其对人脐静脉内皮细胞中OX40L表达的影响

目的观察氧化型低密度脂蛋白(Oxidized low-density lipoprotein,ox-LDL)的内皮损伤作用及其对人脐静脉内皮细胞(Human umbilical vein endothelial cell,HUVEC)中OX40L表达的影响。方法采用CCK-8法检测不同浓度ox-LDL(50、100和150 mg/L)对HUVEC增殖活力的影响;流式细胞术检测100 mg/L ox-LDL处理的HUVEC细胞周期及凋亡率的变化;Western blot法检测不同浓度ox-LDL(50、100和150 mg/L)处理的HUVEC中OX40L蛋白的表达水平;免疫荧光及激光共聚焦检测100 mg/L ox-LDL处理的HUVEC中OX40L蛋白的定位,均设加入等量培养基的HUVEC作为对照组。结果与对照组相比,随着ox-LDL浓度的升高,HUVEC的增殖活力明显降低,差异均有统计学意义(P<0.01);ox-LDL 100 mg/L组细胞被阻滞在S期,凋亡率明显增加,差异均有统计学意义(P<0.05);与对照组相比,随着ox-LDL浓度的升高,HUVEC中OX40L的表达量逐渐升高,差异均有统计学意义(P<0.05);ox-LDL100 mg/L组HUVEC表达OX40L的荧光明显增强,差异有统计学意义(P<0.01),且OX40L蛋白定位于细胞膜及细胞质上。结论 ox-LDL对HUVEC具有明显的损伤作用,可促进HUVEC中OX40L的表达,影响OX40/OX40L炎症信号通路。     

15-Lipoxygenase-Mediated Modification of HDL3 Impairs eNOS Activation in Human Endothelial Cells

Caveolae are cholesterol and glycosphingolipids-enriched microdomains of plasma membranes. Caveolin-1 represents the major structural protein of caveolae, that also contain receptors and molecules involved in signal transduction pathways. Caveolae are particularly abundant in endothelial cells, where they play important physiological and pathological roles in regulating endothelial cell functions. Several molecules with relevant functions in endothelial cells are localized in caveolae, including endothelial nitric oxide synthase (eNOS), which regulates the production of nitric oxide, and scavenger receptor class B type I (SR-BI), which plays a key role in the induction of eNOS activity mediated by high density lipoproteins (HDL). HDL have several atheroprotective functions, including a positive effect on endothelial cells, as it is a potent agonist of eNOS through the interaction with SR-BI. However, the oxidative modification of HDL may impair their protective role. In the present study we evaluated the effect of 15-lipoxygenase-mediated modification of HDL₃ on the expression and/or activity of some proteins localized in endothelial caveolae and involved in the nitric oxide generation pathway. We found that after modification, HDL₃ failed to activate eNOS and to induce NO production, due to both a reduced ability to interact with its own receptor SR-BI and to a reduced expression of SR-BI in cells exposed to modified HDL. These findings suggest that modification of HDL may reduce its endothelial-protective role also by interfering with vasodilatory function of HDL.     

High Density Lipoprotein Level is Negatively Associated With the Increase of Oxidized Low Density Lipoprotein Lipids After a Fatty Meal

Recent reports show that a fatty meal can substantially increase the concentration of oxidized lipids in low density lipoprotein (LDL). Knowing the LDL‐specific antioxidant effects of high density lipoprotein (HDL), we aimed to investigate whether HDL can modify the postprandial oxidative stress after a fatty meal. Subjects of the study (n = 71) consumed a test meal (a standard hamburger meal) rich in lipid peroxides, and blood samples were taken before, 120, 240, and 360 min after the meal. The study subjects were divided into four subgroups according to the pre‐meal HDL cholesterol value (HDL subgroup 1, 0.66–0.91; subgroup 2, 0.93–1.13; subgroup 3, 1.16–1.35; subgroup 4, 1.40–2.65 mmol/L). The test meal induced a marked postprandial increase in the concentration of oxidized LDL lipids in all four subgroups. The pre‐meal HDL level was associated with the extent of the postprandial rise in oxidized LDL lipids. From baseline to 6 h after the meal, the concentration of ox‐LDL increased by 48, 31, 24, and 16 % in the HDL subgroup 1, 2, 3, and 4, respectively, and the increase was higher in subgroup 1 compared to subgroup 3 (p = 0.028) and subgroup 4 (p = 0.0081), respectively. The pre‐meal HDL correlated with both the amount and the rate of increase of oxidized LDL lipids. Results of the present study show that HDL is associated with the postprandial appearance of lipid peroxides in LDL. It is therefore likely that the sequestration and transport of atherogenic lipid peroxides is another significant mechanism contributing to cardioprotection by HDL.     

Ground Beef High in Total Fat and Saturated Fatty Acids Decreases X Receptor Signaling Targets in Peripheral Blood Mononuclear Cells of Men and Women

We hypothesized that consumption of saturated fatty acids in the form of high‐fat ground beef for 5 weeks would depress liver X receptor signaling targets in peripheral blood mononuclear cells (PBMC) and that changes in gene expression would be associated with the corresponding changes in lipoprotein cholesterol (C) concentrations. Older men (n = 5, age 68.0 ± 4.6 years) and postmenopausal women (n = 7, age 60.9 ± 3.1 years) were assigned randomly to consume ground‐beef containing 18% total fat (18F) or 25% total fat (25F), five patties per week for 5 weeks with an intervening 4‐week washout period. The 25F and 18F ground‐beef increased (p < 0.05) the intake of saturated fat, monounsaturated fat, palmitic acid, and stearic acid, but the 25F ground‐beef increased only the intake of oleic acid (p < 0.05). The ground‐beefs 18F and 25F increased the plasma concentration of palmitic acid (p < 0.05) and decreased the plasma concentrations of arachidonic, eicosapentaenoic, and docosahexaenic acids (p < 0.05). The interventions of 18F and 25F ground‐beef decreased very low‐density lipoprotein C concentrations and increased particle diameters and low‐density lipoprotein (LDL)‐I‐C and LDL‐II‐C concentrations (p < 0.05). The ground‐beef 25F decreased PBMC mRNA levels for the adenosine triphosphate (ATP) binding cassette A, ATP binding cassette G1, sterol regulatory element binding protein‐1, and LDL receptor (LDLR) (p < 0.05). The ground‐beef 18F increased mRNA levels for stearoyl‐CoA desaturase‐1 (p < 0.05). We conclude that the increased LDL particle size and LDL‐I‐C and LDL‐II‐C concentrations following the 25F ground‐beef intervention may have been caused by decreased hepatic LDLR gene expression.     

PCSK9 is Present in Human Cerebrospinal Fluid and is Maintained at Remarkably Constant Concentrations Throughout the Course of the Day

Proprotein convertase subtilisin kexin type 9 (PCSK9) is a key regulator of serum low density lipoprotein cholesterol levels. PCSK9 is secreted by the liver and binds the hepatic low density lipoprotein receptor, causing its subsequent degradation. PCSK9 has also been shown to regulate the levels of additional membrane-bound proteins in vitro, including very low-density lipoprotein receptor, apolipoprotein E receptor 2, and beta-site amyloid precursor protein-cleaving enzyme 1, which are highly expressed in central nervous system (CNS) and have been implicated in Alzheimer’s disease. Previous studies have demonstrated that human circulating PCSK9 displays a diurnal rhythm. Currently, little is known about PCSK9 levels in human cerebrospinal fluid (CSF). In the present study, we measured PCSK9 concentrations in both serum and CSF collected from healthy human subjects at multiple time points throughout the day. While PCSK9 in serum manifested a distinct diurnal pattern, CSF PCSK9 levels were remarkably constant throughout the course of the day and were also consistently lower than corresponding serum PCSK9 concentrations. Our results indicate that regulation of PCSK9 in human CSF may be different than for plasma PCSK9, suggesting that further study of the role of PCSK9 in the CNS is warranted.     

Polyurethane films modified by antithrombin–heparin complex to enhance endothelialization: An original impedimetric analysis

In this paper, polyurethane (PU) was deposited as a thin layer onto the surface of ITO (indium tin oxide) and was then modified with an antithrombin–heparin complex (ATH). The resulting films were characterized by ATR spectroscopy, contact angle measurements and electrochemical impedance spectroscopy (EIS). Physicochemical characterization confirmed the surface modifications.The obtained films were used as substrates for endothelial cell attachment and growth. These processes were characterized using electrochemical impedance spectroscopy (EIS). We observed that the addition of a small amount of heparin and AT additives onto the polymer surface resulted in a considerable change in the surface characteristics, and we found that PU films that were modified by the ATH complex were able to greatly enhance adhesion and proliferation of endothelial cells (ECs).     

Chemical Characterization of a High‐Oleic Soybean Oil

High‐oleic low‐linolenic acid soybean oil (HOLLSB, Plenish^®) is an emerging new oil with projections of rapid expansion in the USA. HOLLSB has important technological advantages, which are expected to drive a gradual replacement of commodity oils used in food applications such as soybean oil. A key technological advantage of HOLLSB is its relatively high oxidation stability. This oxidation stability is the result of a favorable fatty acid composition, high (76%) oleic acid, low linoleic (6.7%), and alpha‐linolenic (1.6%) acids, and high concentration of tocopherols (936 ppm) after refining, enriched with the gamma‐homolog (586 ppm). A detailed analysis of the fatty acid composition of this HOLLSB by gas chromatography–mass spectrometry allowed the identification and structural determination of 9‐cis‐heptadecenoic acid (or 17:1n‐8). To our knowledge, this is the first time 9‐cis‐heptadecenoic acid has been unequivocally reported in soybean oil. This unusual fatty acid component has the potential to be used as a single authenticity marker for the quantitative assessment of soybean oil. The Rancimat induction period (IP) of Plenish^® (16.1 hours) was higher than those of other commercially available high‐oleic oils, such as canola (13.4 hours), and Vistive^® Gold (10 hours), a different variety of soybean oil. Plenish^® showed the same IP as high‐oleic sunflower oil. Plenish^® shows a modest increase in oxidation stability with the external addition or relatively high concentrations of tocopherols. The characteristic high oxidative stability of Plenish^® may be further enhanced with the use of nontocopherol antioxidants.     

Soybean and Soybean/Beef-Tallow Biodiesel: A Comparative Study on Oxidative Degradation During Long-Term Storage

Vegetable oils are the primary raw materials used in biodiesel production; however, they usually present oxidative stabilities inferior to the EN 14214 specifications. An alternative to improve the oxidative quality of vegetable oil biodiesel is blending it with animal fat biodiesel. In this paper, we studied the oxidative degradation of soybean/beef-tallow biodiesel (SB) 70/30 and 50/50 (w/w) during long-term storage. Soybean biodiesel (SO) was used as a control sample. The biodiesel samples were stored for 350 days and analyzed periodically via oxidative stability, tocopherol content, peroxide value, polar compounds, and kinematic viscosity. The results showed that SB 70/30 and 50/50 biodiesel samples presented higher oxidative stabilities than SO biodiesel. Additionally, the blends met the limits proposed by EN 14214 for oxidative stability (8 h). During long-term storage, the SB biodiesel showed greater resistance to oxidative degradation, which was indicated by the lower formation of hydroperoxides and polar compounds. Similarly, the decline in the tocopherol content was slower in SB biodiesel. Blends of soybean and beef-tallow biodiesel at levels of 70/30 and 50/50 are, therefore, proper alternatives to improve the oxidative quality of this biofuel.     

Plasma HDL Reduces Nonesterified Fatty Acid Hydroperoxides Originating from Oxidized LDL: a Mechanism for Its Antioxidant Ability

The antioxidant property of plasma high-density lipoprotein (HDL) is thought to be involved in potential anti-atherogenic effects but the exact mechanism is not known. We aimed to reveal the contribution of HDL on the elimination of lipid hydroperoxides (LOOH) derived from oxidized low-density lipoprotein (LDL). Oxidized LDL prepared by copper ion-induced oxidation contained nonesterified fatty acid hydroperoxides (FFA-OOH) and lysophosphatidylcholine (lysoPtdCho), in addition to cholesteryl ester hydroperoxides (CE-OOH) and phosphatidylcholine hydroperoxides (PtdCho-OOH). A platelet-activating factor-acetylhydrolase (PAF-AH) inhibitor suppressed formation of FFA-OOH and lysoPtdCho in oxidized LDL. Among LOOH species, FFA-OOH was preferentially reduced by incubating oxidized LDL with HDL. HDL exhibited selective FFA-OOH reducing ability if it was mixed with a liposomal solution containing FFA-OOH, CE-OOH and PtdCho-OOH. Two-electron reduction of the hydroperoxy group to the hydroxy group was confirmed by the formation of 13-hydroxyoctadecadienoic acid from 13-hydroperoxyoctadecadienoic acid in HPLC analyses. This reducing effect was also found in apolipoprotein A-1 (apoA-1). FFA-OOH released from PtdCho-OOH due to PAF-AH activity in oxidized LDL undergo two-electron reduction by the reducing ability of apoA1 in HDL. This preferential reduction of FFA-OOH may participate in the mechanism of the antioxidant property of HDL.     

Proteomic Analysis Reveals PGAM1 Altering cis‐9, trans‐11 Conjugated Linoleic Acid Synthesis in Bovine Mammary Gland

cis‐9, trans‐11 Conjugated linoleic acid (CLA) is one of the most extensively studied CLA isomers due to its multiple isomer‐specific effects. However, the molecular mechanisms of cis‐9,trans‐11 CLA synthesis in ruminant mammary gland are still not clearly understood. This process may be mediated, to a certain extent, by trans‐11 C18:1 regulated by stearoyl‐CoA desaturase‐1 (SCD1) and/or its syntrophic proteins. This study aimed to investigate the effects of TVA on SCD1‐mediated cis‐9,trans‐11 CLA synthesis in MAC‐T cells and its potential molecular mechanism. Results showed that trans‐11 C18:1 was continually taken up and converted into cis‐9,trans‐11 CLA in MAC‐T cells during the 4‐h incubation of 50 μM trans‐11 C18:1. SCD1 protein expression increased more than twofold at 2 h (P < 0.01) and 2.5 h (P < 0.05) before decreasing to less than half of the normal level at 4 h (P < 0.05). One up‐regulated (RAS guanyl releasing protein 4 isoform 1 [RASGRP4]) and six down‐regulated proteins (glucosamine‐6‐phosphate deaminase 1 [GNPDA1], triosephosphate isomerase [TPI1], phosphoglycerate mutase 1 [PGAM1], heat shock protein beta‐1 [HSPB1], annexin A3 [ANXA3], thiopurine S‐methyltransferase [TPMT]) were found in MAC‐T cells treated with trans‐11 C18:1. Of these seven identified proteins, the presence of GNPDA1 and PGAM1 was verified in several models. More trans‐11 C18:1 was taken up after PGAM1 knockdown by small interfering RNA (siRNA). In conclusion, our data suggested that PGAM1 may have a negative relationship with SCD1 and seemed to be involved in cis‐9, trans‐11 CLA synthesis by facilitating the absorption of trans‐11 C18:1 in the bovine mammary gland.     

Direct ethanol fuel cells with catalysed metal mesh anodes

Platinum based binary and ternary catalysts prepared by thermal decomposition on titanium mesh were characterised and compared in terms of the electrochemical activity for ethanol oxidation. An enhancement in the catalytic activity was observed for the binary catalyst containing tin and ruthenium in their compositions with platinum. The catalysts were tested in single direct ethanol fuel cells and the result obtained with PtRu and PtSn showed that the mesh based electrodes show competitive performance in comparison to the conventional carbon based anodes.