桂皮醛上调Nrf2改善衰老大鼠血管内皮功能障碍

目的:探讨桂皮醛对衰老大鼠模型血管内皮功能的影响及相关机制。方法:通过建立24月龄自然衰老的Sprague Dawley(SD)大鼠模型及第14代的衰老人脐静脉内皮细胞模型(HUVECs),以桂皮醛(10μM)进行体外干预,分别以DHE染色和DAF-2DA染色观察桂皮醛对颈动脉内膜和HUVEC中超氧阴离子、一氧化氮水平的影响。以微血管张力测定仪观察桂皮醛对乙酰胆碱诱导的颈动脉内皮依赖性舒张功能和硝酸甘油诱导的非内皮依赖性舒张功能的影响。Western blotting观察磷酸化eNOS水平及Nrf2表达。结果:桂皮醛孵育显著减少改善衰老大鼠颈动脉内膜和衰老HUVEC的ROS水平,促进HUVEC中eNOS的磷酸化,增加NO水平,改善乙酰胆碱诱导的血管内皮依赖性舒张功能,对硝酸甘油诱导的非内皮依赖性舒张功能无显著的影响;Nrf2的抑制剂鸦胆子苦醇可显著阻断桂皮醛的作用。结论:桂皮醛通过Nrf2通路减少衰老相关的ROS生成,增加NO水平从而改善衰老大鼠血管内皮依赖性舒张功能。     

超氧阴离子抑制大鼠肠系膜阻力血管内皮依赖性舒张功能

目的:研究超氧阴离子对大鼠肠系膜阻力血管内皮细胞超极化因子(EDHF)和一氧化氮(NO)引起的血管舒张作用的影响及其可能机制.方法:雄性Sprague-Dawley大鼠,取肠系膜血管三级分支约2 mm长血管环,置于DMT 610 M系统,记录张力变化.血管环浴液中加入焦酚建立超氧阴离子损伤模型.结果:焦酚(10,100,300和1 000 μmol/L)可浓度依赖性地引起乙酰胆碱(ACh)诱导的肠系膜阻力血管舒张功能减弱;其中,300 μmol/L焦酚显著减弱肠系膜血管环由ACh诱导的EDHF和NO介导的内皮依赖性血管舒张效应,但对硝普钠和吡那地尔引起的内皮非依赖性的血管舒张作用无明显影响.结论:超氧阴离子可减弱阻力血管内皮依赖性舒张反应,其机制可能与超氧阴离子抑制了阻力血管内皮细胞EDHF和NO的作用有关.     

普伐他汀对溶血磷脂酰胆碱所致血管内皮功能损伤的保护作用及机制探讨

目的:探讨不同剂量的普伐他汀对溶血磷脂酰胆碱(LPC)所致血管内皮功能的影响.方法:用离体血管环和培养的人脐静脉内皮细胞(HUVECs)为实验模型,以血管内皮依赖性舒张反应(EDR)、内皮细胞活力以及生化参数为指标,用LPC作为损伤因子,用普伐他汀作为保护药,观察LPC对内皮的损伤作用及普伐他汀的保护作用.结果:LPC与血管环共孵或内皮细胞显著性地抑制了血管EDR反应,增加了血管MDA含量,并导致培养的内皮细胞的活力、内皮型一氧化氮合酶(eNOS)活性及一氧化氮(NO)含量显著性降低;普伐他汀与血管环或内皮细胞共孵,浓度依赖性地减轻了LPC对血管EDR的抑制作用(P＜0.05),保护了内皮细胞的活力(P＜0.05).恢复了细胞eNOS活性及NO含量(P＜0.05),抑制了内皮细胞活性氧(ROS)的生成(P＜0.05).结论:LPC能直接损伤的血管内皮细胞,普伐他汀对LPC所致的血管内皮细胞损伤有显著性保护作用,其机制可能与LPC触发脂质过氧化反应,从而抑制血管内皮血管内皮细胞NO的合成有关,普伐他汀通过抗氧化而保护血管内皮细胞的功能.     

姜黄素激活AMPK抑制高糖介导的氧化应激水平升高致血管内皮功能障碍

目的:探索姜黄素对高糖介导的血管氧化应激水平的升高和血管功能的保护作用未知及相关的机制。方法:以高糖DMEM培养基复制人脐静脉内皮细胞(HUVECs)的高糖损害模型。姜黄素干预24h后以DHE荧光探针分析姜黄素对高糖介导的活性氧产生的影响;分离健康C57BL/6J小鼠胸主动脉,以高糖DMEM培养基进行体外培养制作高糖介导的血管损害模型,分析姜黄素对高糖介导的血管功能的影响。利用western blotting方法检测血管内皮细胞中p-e NOS及p-AMPK的表达水平。结果:姜黄素可显著减少高糖介导的血管内皮细胞活性氧水平,该作用在给予AMPK抑制剂后显著降低;姜黄素可显著促进高糖环境血管内皮细胞e NOS的磷酸化并可显著改善高糖环境下小鼠胸主动脉的血管内皮依赖性舒张功能。Western blotting结果表明,姜黄素可显著增加p-AMPK的表达。结论:姜黄素显著减轻高糖血管内皮细胞的氧化应激水平,改善血管内皮依赖性舒张功能,而该作用可能与其通过激活AMPK/e NOS通路有关。     

四氢生物蝶呤与血管内皮功能异常

血管内皮功能异常突出表现为内皮依赖性血管舒张功能障碍 ,主要由NO减少及氧自由基增加所致。四氢生物蝶呤 (tetrahydrobiopterin ,BH4 )是NO合酶 (NOS)的必要辅助因子 ,影响NO和氧自由基生成。BH4充足时 ,NOS催化底物L 精氨酸和O2 生成L 胍氨酸和NO ;BH4缺乏时 ,NOS则发生脱偶联 (uncoupling) ,主要催化超氧阴离子产生。BH4缺乏是高血压、糖尿病、动脉粥样硬化等疾病中内皮功能异常的重要原因 ,用BH4替代治疗提高内皮细胞内BH4水平可有效改善内皮功能 ,可望为保护血管内皮功能提供有效途径     

香椿子正丁醇提取物通过激活Nrf2改善高糖引起的肾小球内皮细胞氧化应激

目的探讨香椿子正丁醇提取物(n-butyl alcohol extract of toona sinensis,NBAE)对高糖引起的肾小球内皮细胞氧化应激的影响及机制。方法分别以高糖(high glucose,HG)、HG+NBAE刺激人肾小球内皮细胞,采用DCFDA法检测细胞内活性氧(reactive oxygenspecies,ROS)生成情况,Nitrate/Nitrite Colorimetric法检测细胞内NO的含量,Western blot检测Nrf2、NQO1及HO-1的蛋白表达,免疫荧光方法检测Nrf2、P47phox在细胞内的定位及表达。结果高糖刺激肾小球内皮细胞后出现氧化应激损伤,ROS升高,NO减少,p47phox表达量增高,Nrf2及下游蛋白NQO1、HO-1表达减少;NBAE可明显提高Nrf2的表达,并增加下游蛋白NQO1和HO-1的表达,从而抑制高糖导致的ROS升高,抑制p47phox的表达,并稳定NO的含量。结论NBAE通过激活Nrf2及其下游靶蛋白来改善高糖对肾小球内皮细胞造成的氧化应激损伤。     

增塑剂邻苯二甲酸二丁酯致血管内皮功能损伤及其机制

邻苯二甲酸二丁酯(DBP)是一种常用的增塑剂,在环境中广泛存在.DBP可以经口、呼吸吸入、皮肤接触、医疗暴露等途径进入人体.已报道DBP具有多种生物毒性,包括遗传毒性、神经毒性、生殖毒性和免疫毒性等.本研究以大鼠(Rattus norvegicus)和小鼠(Mus musculus)胸主动脉以及牛(Bovine)主动脉血管内皮细胞为研究对象,揭示增塑剂DBP对血管内皮功能的影响.实验分别采用不同浓度的DBP(0,5,25μmol/L)对大鼠和小鼠胸主动脉进行体外孵育,采用血管张力仪检测血管舒张功能的变化.分别采用一氧化氮(NO)探针和活性氧簇(ROS)探针,检测血管内皮细胞内NO和ROS含量.实时定量PCR和蛋白免疫印迹技术检测DBP对血管内皮细胞NLRP3炎症小体的激活作用.结果表明,DBP浓度依赖性损伤大鼠和小鼠血管舒张功能;在培养的内皮细胞中,DBP减少了NO的释放,增加了ROS的含量;DBP能够激活内皮细胞NLRP3炎症小体,且ROS清除剂二联苯碘能够抑制DBP引起的NLRP3炎症小体的激活,改善DBP引起的血管舒张功能障碍.上述结果提示,增塑剂DBP对血管内皮功能的损伤可能与ROS引起的NLRP3炎症小体的激活以及NO释放减少有关.     

肾上腺髓质素2的降压作用及其机制

目的:研究肾上腺髓质素2(ADM2)拮抗血管紧张素Ⅱ(AngⅡ)发挥舒张血管的作用及机制。方法:将18只180~200 g雄性SD大鼠随机分为3组(n=6):对照组、AngⅡ(150 ng/(kg·min))组和AngⅡ(150 ng/(kg·min))+ADM2(500 ng/(kg·h))组,采用皮下埋植微量渗透泵的方法给药。2周后颈动脉插管法测量大鼠血压,测定血浆一氧化氮(NO)含量和内皮型一氧化氮合酶(eNOS)活性。DHE染色法检测大鼠动脉壁活性氧产生。制备大鼠离体血管环,观察ADM2的舒血管作用。培养人脐静脉内皮细胞系EA.hy 926,用DCFH-DA荧光探针检测AngⅡ和ADM2对血管内皮细胞活性氧释放的影响。结果:与AngⅡ组相比,ADM2显著降低了大鼠血压,血浆中eNOS活性提高、NO含量增加,血管壁活性氧产生减少。ADM2呈浓度依赖性和内皮依赖性舒张血管环,并明显抑制了AngⅡ引起的血管内皮细胞活性氧产生。结论:ADM2可能通过拮抗AngⅡ诱导的血管内皮氧化应激效应,改善内皮功能,发挥舒张血管、降低血压的作用。     

一种新发现的血管内皮依赖性物质——EDHF

日本学者H.Suzuki与G.Chen最近综合报道一种由血管内皮细胞产生的物质,称为内皮依赖性超极化因子(endothelium derived hyperpolarizing factor,EDHF)。这种因子由内皮细胞释放后引起平滑肌细胞膜超极化,从而引起血管舒张。EDHF与内皮依赖性舒张因子(endothelium derive relaxing factor,EDRF)     

大、小动脉内皮细胞乙酰胆碱作用靶标药理学特性的比较

目的 :比较大、小动脉内皮细胞乙酰胆碱作用靶标药理学特性的差异。方法 :采用大鼠尾动脉螺旋状血管条和主动脉离体血管环两种组织 ,对比观察乙酰胆碱 (ACh)诱发大、小动脉内皮依赖性舒张反应特征的差异 ,从而进一步研究小动脉内皮细胞乙酰胆碱作用靶标的药理学特性。结果 :氯化钾 (6 0mmol/L)预致血管收缩的尾动脉和主动脉对不同浓度ACh (10 -8～ 10 -4mol/L)产生内皮依赖性舒张反应 ,且呈剂量依赖性。L Nω 硝基精氨酸甲酯 (L NAME :10 -4mol/L)或美蓝 (MB :10 -5mol/L)与吲哚美辛 (Indo :10 -4mol/L)联用仅可部分地阻断ACh诱发尾动脉内皮依赖性舒张反应 ;而L NAME或MB可完全阻断ACh诱发主动脉内皮依赖性舒张反应。结论 :ACh激活大、小动脉上内皮细胞乙酰胆碱作用靶标诱发内皮依赖性舒张反应的药理学性质不同 ,在小动脉上 ,除了NO和PGI2介导外 ,还有一种非NO和非PGI2 的舒血管因子参与 ;在大动脉上 ,内皮依赖性舒张反应主要由NO介导     

Oviposition by Lobesia botrana is stimulated by sugars detected by contact chemoreceptors

Abstract.  The influence of glucose, fructose and sucrose on oviposition site selection by Lobesia botrana is studied by combining behavioural and electrophysiological experiments. Oviposition choice assays, using surrogate grapes treated with grape berry surface extracts of Vitis vinifera cv. Merlot at different development stages, show that L. botrana females are most stimulated by extracts of mature berries containing the highest concentrations of glucose and fructose. Choice assays reveal that the oviposition response to these sugars is dose-dependant (with a threshold of the applied solution = 10 m m and a maximum stimulation at 1  m ) and that females are more sensitive to fructose than to glucose. Tarsal contact-chemoreceptor sensilla are unresponsive to stimulation with sugars but the ovipositor sensilla contain at least one neurone most sensitive to fructose and sucrose with a threshold of approximately 0.5 m m . Corresponding to the behavioural data, glucose is significantly less stimulatory to sensilla than fructose or sucrose. It is argued that fructose may be of special importance for herbivorous insects exploiting fruit as an oviposition site.     

Log colonization by Ips sexdentatus prevented by increasing host unsuitability signaled by verbenone

Sudden increments of breeding material after windstorms, forest fires, or inappropriate management practices help bark beetles such as Ips sexdentatus Boerner (Coleoptera: Curculionidae: Scolytinae) increase in numbers and colonize standing healthy pine trees. Preventing bark beetles from arriving to susceptible trees or logs may have great relevance for bark beetle management. Recent studies have reported inhibition of the aggregation response of I. sexdentatus using verbenone. Two field experiments were conducted to examine the effect of verbenone on the colonization pattern of this beetle. The first experiment tested the combined effect of trans‐conophthorin, a non‐host bark volatile with known repellent effect, and verbenone on Pinus sylvestris L. (Pinaceae) log piles of two sizes, but failed to protect them against I. sexdentatus attack when these two infochemicals were released at low rates. The results of this experiment suggested an interaction with the associated secondary bark beetle Orthotomicus erosus (Wollaston). A second experiment examined the response of I. sexdentatus and O. erosus to log piles that released verbenone at 0, 2, 10, or 40 mg day^?1. Although I. sexdentatus colonization of Pinus nigra Arnold logs was completely prevented at 40 mg day^?1, O. erosus could be found at all tested verbenone release rates. Besides verbenone, O. erosus colonization density and the height from which logs originated were the variables that best explained I. sexdentatus log colonization pattern. In addition, I. sexdentatus and O. erosus were rarely recorded colonizing the same log, and niche breadth analyses suggested that they excluded each other. The role of verbenone in the colonization process and its potential use in the prevention of population buildups of damaging bark beetles such as I. sexdentatus are discussed.     

Inch by inch, row by row

Bacterial chemotaxis systems have cooperatively interacting clusters of transmembrane receptors and signaling proteins to detect, amplify, integrate and adapt to environmental signals. A recent study provides experimental data to construct a new model of the signaling complex.     

Reactivation by copper of phenolase pre-inactivated by oxalate

The activity of spinach chloroplast phenolase which had been repressed by ammonium oxalate was restored by adding copper. Oxalate appears to bind to the enzyme at a single site, the binding paralleling the inhibition produced at neutral pH. The inhibition of oxalate is due to its binding with copper at the active centre to form an inactive complex, the oxalate moiety of which is releasable when more copper is added. Similar reactivation by copper was obtained with pure mushroom phenolase.     

Anthracenediethanol inhibits lignin degradation by Phanerochaete chrysosporium by competing for oxidation by lignin peroxidase,and not by trapping singlet oxygen

The biodegradation of anthracene-9, 10-diethanol by the ligninolytic fungus Phanerochaete chrysosporium, previously though to involve singlet oxygen, is shown to be catalyzed by lignin peroxidases. Veratryl alcohol stimulated the enzymatic degradation of anthracenediethanol, and anthracenediethanol inhibited enzymatic oxidation of veratryl alcohol. Competition for oxidation by lignin peroxidase is suggested as the mechanism of the inhibition of lignin biodegradation by anthracenediethanol and related anthracene derivatives.Abbreviations ADE anthracene-9,10-diethanol - AES anthracene-9,10-bisethanesulfonic acid - DHP dehydrogenative polymerizate - DMF N,N-dimethylformamide - EPX 9,10-endoperoxide of ADE - PMR proton magnetic resonance     

Separation by capillary electrophoresis followed by dynamic elution

In this study we have explored the behaviour of peptides after capillary electrophoresis (CE) followed by elution under pressure. The use of D2O- rather than H2O-based buffer solutions appears to restrict the diffusion of peptides after CE, resulting in little loss of resolution when peptides are eluted by dynamic flow. In this paper we present results showing that a simple two-step process, involving CE at a low voltage, switching off the power supply, and connecting the fused capillary at the anode end to a syringe pump for dynamic flow, can retain separation characteristics and can be used for the isolation of picomole quantities of peptides for sequence determination.     

Polarity induced by chloramphenicol and relief by suA

The suA allele, known to relieve polarity in Escherichia coli, also relieves a unique polar effect on E. coli tryptophan operon messenger RNA produced by chloramphenicol.     

Chemicomechanical transduction performed by enzymes activated by polymers

Kinetic models for the mode of action of processive and non-processive DNA-helicases are detailed. Fluxes at the steady state are analyzed, and the random walk of the enzymes on the DNA is studied in connection with the rate constants of the chemical reactions involved in the transformation of substrate to products. Finally, the constants of the kinetic model for the processive helicase are related to the parameters of an analogous viscoelastic model.