何首乌苷通过激活BDNF/TrkB信号通路拮抗H2O2诱导的大鼠海马神经元氧化损伤

探讨脑源性神经营养因子/酪氨酸激酶受体B(BDNF/TrkB)信号通路激活参与何首乌苷(PMG)对过氧化氢(H2O2)诱导神经元氧化应激损伤的保护作用。实验采用神经元原代培养,建立大鼠乳鼠海马神经元氧化应激损伤模型。实验结果显示高浓度的H2O2与MTT测定的细胞存活率降低相关,选择细胞存活率在40%~50%之间的200μmol/LH2O2浓度作为氧化应激损伤的实验浓度。与模型组相比,PMG预处理组(200μmol/L)可抑制H2O2诱导的神经元损伤(P<0.001)。TUNEL和β-微管蛋白III荧光染色显示PMG保护H2O2诱导的神经细胞损伤,明显降低细胞凋亡率(P<0.001),细胞骨架形态恢复正常。与PMG+H2O2预处理组相比较,当加入BDNF/TrkB信号转导通路阻断剂K252a后,PMG+H2O2+K252a组神经元细胞存活率大幅度下降(P<0.01),细胞骨架形态呈损伤状态。同时,我们发现PMG预处理恢复H2O2诱导的BDNF和P-TrkB的低表达水平,并且用K252a阻断BDNF/TrkB信号传导抑制了PMG对BDNF和P-TrkB表达水平的影响(P<0.01)。综上所述,何首乌苷可能通过激活BDNF/TrkB信号转导通路及维护神经元骨架的完整,实现对大鼠海马神经元氧化应激损伤的拮抗作用。     

双酚A 对雄性大鼠抗氧化能力影响的初步研究

目的:探讨双酚A(BPA)对成年大鼠抗氧化能力的影响。方法:将健康成年雄性SD大鼠84只随机分为5个双酚A染毒剂量组(200、50、5、0.5、0.0005 mg/kg)和1个对照组,连续灌胃染毒8周,并监测体重变化,染毒结束后测定血浆超氧化物歧化酶(SOD)和谷胱甘肽-过氧化物酶(GSH-Px)含量;此外,提取肝脏组织RNA,用荧光实时定量PCR测定肝脏硫氧还原蛋白过氧化物酶2(prdx2)mRNA的表达水平。结果:随着染毒时间的延长,50 mg/kg及200 mg/kg剂量组的动物体重增长速度逐渐减慢,自4周开始,与对照组相比有显著差异(P<0.05);染毒结束时,其体重分别为对照组的90.52%和91.61%(p<0.05),而其它低剂量组间则无明显差异;大鼠血浆GSH-Px含量总体上呈下降趋势,且5 mg/kg以上剂量组与对照组相比差别均有统计学意义(p<0.01);染毒组血浆SOD水平虽也低于对照组,但无统计显著性;此外,大鼠肝脏组织prdx2 mRNA水平随双酚A剂量增高呈剂量依赖性降低,与对照组相比,其在最低剂量组(0.0005 mg/kg)即有显著差异(p<0.01)。结论:双酚A可造成大鼠抗氧化酶系统失衡,导致氧化损伤效应,prdx2可能是反映其氧化损伤敏感的生物学标志。     

肝郁脾虚证模型大鼠血流变及TXB2、PGFla的变化

目的:探查中医肝郁脾虚证模型的血流变及相关调节因子的状态。方法:采用慢性束缚应激+过度疲劳+饮食失节法建立大鼠肝郁脾虚证模型,测定大鼠造模三周、自然恢复一周时的血流变和血浆TXB2、PGF1a。结果:与正常组相比,模型组大鼠造模三周150/s、38/s、10/s、5/s切变率下的全血粘度、还原粘度均显著升高(P<0.001),红细胞聚集指数显著降低(P<0.001),红细胞压积显著升高(P<0.01),红细胞变形指数无显著性差异(P>0.05);血浆TXB2显著升高(P<0.001),6-keto-PGF1a显著降低(P<0.05),TXB2/PGF1a显著升高(P<0.01);模型组大鼠第四周150/s、38/s、10/s、5/s切变率下的全血粘度、还原粘度仍显著升高(P<0.001或P<0.01);红细胞聚集指数显著降低(P<0.001);红细胞压积与变形指数无显著性差异(P>0.05);血浆TXB2和TXB2/PGF1a显著降低(P<0.05),6-keto-PGF1a显著升高(P<0.05)。结论:肝郁脾虚证大鼠存在血液高粘和血栓易形成状态,恢复期血液高粘同时伴有扩血管因素的加强。提示肝郁脾虚证有血流...     

糖尿病大鼠外周神经山梨醇通路和Na^＋—K^＋—ATP酶活性的变化

本文用四氧嘧啶诱导产生糖尿病动物模型,分别于糖尿病产生后第4,8,12周测定大鼠坐骨神经匀浆山梨醇通路活性,肌醇含量和哇巴因敏感的和不敏感的 ATP 酶活性。与同龄正常对照组比较,糖尿病发生4周后,坐骨神经葡萄糖含量增加3—4倍,果糖增加3—5倍,山梨醇增加6—9倍,肌醇含量降低到对照组的50%,总 ATP 酶和哇巴因敏感的Na~+-K~+-ATP 酶活性均极显著地低于同龄对照组(P<0.01)。结果提示这些代谢变化可能是糖尿病神经病变发病机制中的重要环节。     

急性毛细支气管炎并心衰患儿血小板活化因子,血小板源生长因子的表达及临床意义

目的:探讨血小板活化因子(PAF)、肿瘤坏死因子-α(TNF-α)及血小板源生长因子(PDGF)水平变化在毛细支气管炎并急性心衰的变化,探讨它们在该病的发病中的作用方法:58例心衰组患儿分别于治疗前和临床症状消失后采用双抗体夹心ABC-ELISA法检测PAF、TNF-α及PDGF血清含量,设正常对照组40例比较。结果:心衰组PAF治疗前为370.57±23.6ng/L,明显高于对照组的56.78±19.6ng/L,组间比较差异具有非常显著性意义(t=15.95,P<0.001);治疗后恢复至49.63±14.5 ng/L,与正常对照差异不明显;治疗前后比较,差异具有非常显著性意义(t=3.70,P<0.001)TNF-α治疗前为457.4±40.5 ng/L,明显高于对照组的148.8±21.6ng/L,组间比较差异具有显著性意义(t=2.135,P<0.05);治疗后恢复至162.6±37.61ng/L,与正常对照差异不明显;治疗前后比较,差异具有非常显著性意义(t=7.25,P<0.01)。PDGF治疗前为596.23±199.43)ng/L,较对照组259.76±69.58ng/L增高,组间比较,差异具有非常显著性意义(t=25.52,P<0.01);治疗后降为272.83±116.96ng/L,较治疗前明显恢复,组间比较差异均具有显著性意义(t=7.66,P<0.01)结论:结果表明,PAF、TNF-α、PDGF作为炎症介质不仅参与心衰的发病过程,还提示细胞外基质的异常在心衰发病学中的重要地位     

急性PM2.5暴露对C57BL/6J小鼠和酒精性脂肪肝病模型小鼠肺组织炎症的影响

目的 研究急性PM2.5暴露对C57BL/6J小鼠和酒精性脂肪肝病模型小鼠肺炎症和NLRP3炎性小体的影响,为防治PM2.5暴露所致急性肺损伤提供靶点。方法 将40只雄性C57BL/6J小鼠随机分为对照组、PM2.5染毒组、酒精性脂肪肝病(AFLD)模型组和AFLD+PM2.5染毒组(AFLD+PM2.5)。连续8周给予小鼠Lieber-DeCarli饮食建立AFLD模型,对照组和PM2.5染毒组给予对照饮食。从第9周开始,通过气管滴注法对PM2.5组和AFLD+PM2.5组小鼠连续7 d进行PM2.5染毒;对照组和AFLD组小鼠同时气管滴注生理盐水。末次染毒结束24 h后将动物处死。测定小鼠血细胞计数水平;用HE染色法观察肺组织的组织病理学改变;用ELISA试剂盒检测3组小鼠肺泡灌洗液中白细胞介素(interleukin, IL-1β),IL-6和TNF-α水平;用实时定量PCR检测肺组织NLRP3炎性小体相关蛋白的mRNA表达水平。结果 PM2.5急性暴露导致小鼠肺泡间隔增宽。与对照组相比,PM2.5染毒组和AFLD-PM2.5组小鼠血中白细胞和单核细胞百分以及肺泡灌洗液中炎性细胞...     

肝郁脾虚证模型大鼠血流变及TXB_2、PGFla的变化（英文）

目的：探查中医肝郁脾虚证模型的血流变及相关调节因子的状态。方法：采用慢性束缚应激＋过度疲劳＋饮食失节法建立大鼠肝郁脾虚证模型,测定大鼠造模三周、自然恢复一周时的血流变和血浆TXB2、PGF1a。结果：与正常组相比,模型组大鼠造模三周150/s、38/s、10/s、5/s切变率下的全血粘度、还原粘度均显著升高（P〈0.001）,红细胞聚集指数显著降低（P〈0.001）,红细胞压积显著升高（P〈0.01）,红细胞变形指数无显著性差异（P〉0.05）;血浆TXB2显著升高（P〈0.001）,6-keto-PGF1a显著降低（P〈0.05）,TXB2/PGF1a显著升高（P〈0.01）;模型组大鼠第四周150/s、38/s、10/s、5/s切变率下的全血粘度、还原粘度仍显著升高（P〈0.001或P〈0.01）;红细胞聚集指数显著降低（P〈0.001）;红细胞压积与变形指数无显著性差异（P〉0.05）;血浆TXB2和TXB2/PGF1a显著降低（P〈0.05）,6-keto-PGF1a显著升高（P〈0.05）。结论：肝郁脾虚证大鼠存在血液高粘和血栓易形成状态,恢复期血液高粘同时伴有扩血管因素的加强。提示肝郁脾虚证有血流变的异常和血浆TXB2-PGI2的平衡失调,主要涉及到血小板和血浆因素的参与。     

双酚A对雄性大鼠抗氧化能力影响的初步研究

目的：探讨双酚A（BPA）对成年大鼠抗氧化能力的影响。方法：将健康成年雄性SD大鼠84只随机分为5个双酚A染毒剂量组（200、50、5、0.5、0.0005 mg/kg）和1个对照组,连续灌胃染毒8周,并监测体重变化,染毒结束后测定血浆超氧化物歧化酶（SOD）和谷胱甘肽-过氧化物酶（GSH-Px）含量;此外,提取肝脏组织RNA,用荧光实时定量PCR测定肝脏硫氧还原蛋白过氧化物酶2（prdx2）mRNA的表达水平。结果：随着染毒时间的延长,50 mg/kg及200 mg/kg剂量组的动物体重增长速度逐渐减慢,自4周开始,与对照组相比有显著差异（P〈0.05）;染毒结束时,其体重分别为对照组的90.52%和91.61%（p〈0.05）,而其它低剂量组间则无明显差异;大鼠血浆GSH-Px含量总体上呈下降趋势,且5 mg/kg以上剂量组与对照组相比差别均有统计学意义（p〈0.01）;染毒组血浆SOD水平虽也低于对照组,但无统计显著性;此外,大鼠肝脏组织prdx2 mRNA水平随双酚A剂量增高呈剂量依赖性降低,与对照组相比,其在最低剂量组（0.0005 mg/kg）即有显著差异（p〈0.01）。结论：双酚A可造成大鼠抗氧化酶系统失衡,导致氧化损伤效应,prdx2可能是反映其氧化损伤敏感的生物学标志。     

+G_z暴露时,家兔心率和心水平动脉压关系的研究

在动物离心机上测定了7只轻度麻醉家免暴露于+G_Z时心、眼水平动脉压和心率的变化。+G_Z作用5-12s时、心水平动脉压(HABP)降至最低水平,然后开始代偿性回升。当+G_Z增大到一定值时,于加速度达峰值后,HABP降为0 mmHg、并在峰值后5.5±1.7s降到最大负值,继之代偿性升为正值,并常再度降为负值。我们称HABP的这种变化状态为“临界状态”。+G_Z暴露时,心率以两种型式发生改变:第一种,随着G值增大,心率发生不同程度增快,当加速度达某一G值时,心率突然减慢至2次/秒左右;第二种,当G值≥3时,在暴露过程中,心率逐渐减慢,并在某一G值,心率减慢到2次/秒左右。心率和HABP关系密切。当HABP达临界状态时,心率减慢至2次/秒左右并出现明显节律不整。以心率减慢到2次/秒左右作为家免+G_Z耐力终点是合适的,该指标规律性强,重复性好,实验方法对动物无损伤又易实施。按此标准,测得7只家免的+G_Z耐力为4.85±0.47G。     

培菲康对肝硬化患者内毒素、血氨水平以及数字连接试验的影响

目的观察培菲康对肝硬化伴肝性脑病患者的内毒素、血氨水平以及联字试验的影响。方法肝硬化患者服用培菲康每次2粒,1日3次,疗程为4周。采用血氨测定仪、鲎试剂法及数字连接试验分别测定血氨水平、血浆内毒素水平及数字连接所需时间。结果与培菲康治疗前相比,肝硬化患者血浆内毒素水平显著降低(0.13±0.04 vs 0.27±0.17,EU/m l,P<0.01);血氨水平显著降低(1.36±1.21 vs 2.14±1.82,ng/L,P<0.001);数字连接试验所需时间显著缩短(58±32 vs 101±30,s,P<0.001)。结论微生态制剂(培菲康)可有效防治肝硬化患者肝性脑病及内毒素血症。     

Carbon disulfide oxidation by a microbial consortium from a trickling filter

Biological oxidation rates of CS₂ with a mixed microbial culture obtained from a trickling filter were optimal with 3 mM CS₂, pH 7, 30°C and SO₄ ^2– below 25 g l^–1. Degradation rates were 3.4 mg CS₂/g_proteinmin and 13.8 mg H₂S/g_proteinmin. The concentrations of intermediates (H₂S, COS and S°) and the product (SO₄ ^2–) of CS₂ oxidation were measured. The biological oxidation was due principally to Gram negative bacteria.     

Carbon‐Sheathed MoS2 Nanothorns Epitaxially Grown on CNTs: Electrochemical Application for Highly Stable and Ultrafast Lithium Storage

Molybdenum disulfide (MoS₂), which possesses a layered structure and exhibits a high theoretical capacity, is currently under intensive research as an anode candidate for next generation of Li‐ion batteries. However, unmodified MoS₂ suffers from a poor cycling stability and an inferior rate capability upon charge/discharge processes. Herein, a unique nanocomposite comprising MoS₂ nanothorns epitaxially grown on the backbone of carbon nanotubes (CNTs) and coated by a layer of amorphous carbon is synthesized via a simple method. The epitaxial growth of MoS₂ on CNTs results in a strong chemical coupling between active nanothorns and carbon substrate via C? S bond, providing a high stability as well as a high‐efficiency electron‐conduction/ion‐transportation system on cycling. The outer carbon layer can well‐accommodate the structural strain in the electrode upon lithium‐ion insertion/extraction. When employed as an anode for lithium storage, the prepared material exhibits remarkable electrochemical properties with a high specific capacity of 982 mA h g^?1 at 0.1 A g^?1, as well as excellent long‐cycling stability (905 mA h g^?1 at 1 A g^?1 after 500 cycles) and superior rate capability, confirming its potential application in high‐performance Li‐ion batteries.     

Restriction of intramolecular movements within the Cry1Aa toxin molecule of Bacillus thuringiensis through disulfide bond engineering

Disulfide bridges were introduced into Cry1Aa, a Bacillus thuringiensis lepidopteran toxin, to stabilize different protein domains including domain I α-helical regions thought to be involved in membrane integration and permeation. Bridged mutants could not form functional ion channels in lipid bilayers in the oxidized state, but upon reduction with β-mercaptoethanol, regained parental toxin channel activity. Our results show that unfolding of the protein around a hinge region linking domain I and II is a necessary step for pore formation. They also suggest that membrane insertion of the hydrophobic hairpin made of α-helices 4 and 5 in domain I plays a critical role in the formation of a functional pore.     

Cross‐strand disulfides in the hydrogen bonding site of antiparallel β‐sheet (aCSDhs): Forbidden disulfides that are highly strained,easily broken

Some disulfide bonds perform important structural roles in proteins, but another group has functional roles via redox reactions. Forbidden disulfides are stressed disulfides found in recognizable protein contexts, which currently constitute more than 10% of all disulfides in the PDB. They likely have functional redox roles and constitute a major subset of all redox‐active disulfides. The torsional strain of forbidden disulfides is typically higher than for structural disulfides, but not so high as to render them immediately susceptible to reduction under physionormal conditions. Previously we characterized the most abundant forbidden disulfide in the Protein Data Bank, the aCSDn: a canonical motif in which disulfide‐bonded cysteine residues are positioned directly opposite each other on adjacent anti‐parallel β‐strands such that the backbone hydrogen‐bonded moieties are directed away from each other. Here we perform a similar analysis for the aCSDh, a less common motif in which the opposed cysteine residues are backbone hydrogen bonded. Oxidation of two Cys in this context places significant strain on the protein system, with the β‐chains tilting toward each other to allow disulfide formation. Only left‐handed aCSDh conformations are compatible with the inherent right‐handed twist of β‐sheets. aCSDhs tend to be more highly strained than aCSDns, particularly when both hydrogen bonds are formed. We discuss characterized roles of aCSDh motifs in proteins of the dataset, which include catalytic disulfides in ribonucleotide reductase and ahpC peroxidase as well as a redox‐active disulfide in P1 lysozyme, involved in a major conformation change. The dataset also includes many binding proteins.     

Folding in vitro of bovine pancreatic trypsin inhibitor in the presence of proteins of the endoplasmic reticulum.

The rates of folding and disulfide bond formation in reduced BPTI were measured in vitro in the presence and absence of total protein from the endoplasmic reticulum. The rates were increased substantially by the endoplasmic reticulum proteins, but only to the extent expected from the known content and activity of protein-disulfide-isomerase. No effects of added ATP or Ca2+ were observed, even though protein-disulfide-isomerase binds Ca2+ tightly.     

肽合成中多对二硫键的形成策略及分析方法

二硫键的正确配对是富含二硫键多肽合成的关键。本文综述了含两对二硫键以上的多肽二硫键的形成策略,优化方法、以及二硫键配对方式的测定方法。     

蛋白质二硫键异构酶家族的结构与功能

蛋白质二硫键异构酶（protein disulfide isomerase,PDI）家族是一类在内质网中起作用的巯基-二硫键氧化还原酶.它们通常含有CXXC（Cys-Xaa-Xaa-Cys,CXXC）活性位点,活性位点的两个半胱氨酸残基可催化底物二硫键的形成、异构及还原.所有PDI家族成员包含至少一个约100个氨基酸残基的硫氧还蛋白同源结构域.PDI家族的主要职能是催化内质网中新生肽链的氧化折叠,另外在内质网相关的蛋白质降解途径（ERAD）、蛋白质转运、钙稳态、抗原提呈及病毒入侵等方面也起重要作用.     

Further experimental studies of the disulfide folding transition of ribonuclease A

Two very different mechanisms of folding have been proposed from experimental studies of disulfide formation in reduced ribonuclease A. (1) A pathway in which the rate-limiting step separates fully folded protein from all other disulfide intermediates and occurs solely in three-disulfide intermediates. (2) A multiple pathway mechanism with different rate-limiting steps for each pathway. The various rate-limiting steps involve disulfide breakage, formation, and rearrangement in intermediates with one, two, three, and four protein disulfides. To distinguish between these two mechanisms, we have carried out further studies of both unfolding and refolding. Refolding of reduced ribonuclease A requires three-disulfide intermediates to accumulate; negligible refolding occurs when only the nearly random one- and two-disulfide intermediate species are populated. Therefore, no rate-limiting steps of the type postulated in mechanism (2) occur in intermediates with one and two protein disulfides. Unfolding and disulfide reduction is an all-or-none process; no disulfide intermediates accumulate to detectable levels or precede the rate-limiting step. Mechanism (2) requires that such intermediates precede the rate-limiting step and accumulate to substantial levels. The different proposals were shown not to result from the use of different solution conditions or disulfide reagents; the two sets of data are not inconsistent. Instead, the inappropriate mechanism (2) resulted from an incorrect kinetic analysis and misinterpretation of the kinetics of disulfide formation and breakage.