红花黄色素调控p38MAPK对H2O2诱导的星形胶质细胞损伤的保护作用

目的中药红花具有悠久的神经保护应用历史,近代研究发现,红花黄色素也具有保护神经作用,但其发挥作用的机制尚未清楚。因此,研究红花黄色素对H_2O_2诱导的星形胶质细胞氧化应激和凋亡的影响并探讨其机制。方法运用H_2O_2诱导建立星形胶质细胞HAs的损伤模型;用红花黄色素(10、50、100 mg/L)治疗损伤细胞;用ELISA检测细胞的LDH、SOD、GSHPX、MDA含量;MTT法检测细胞活性;Western blot检测细胞中Bax、Bcl-2、Caspase-3、p-p38、T-p38MAPK的蛋白表达;流式细胞术检测细胞的凋亡率。结果成功构建H_2O_2诱导的星形胶质细胞HAs损伤模型;与H_2O_2组相比,红花黄色素(10、50、100 mg/L)治疗组细胞中LDH、MDA均显著降低,SOD、GSH-PX均显著升高,细胞活性均显著降低,细胞凋亡率均显著降低,Bcl-2蛋白表达显著升高,Bax、Caspase-3、p-p38蛋白表达均显著降低(P0.05),且此种影响随与红花黄色素呈浓度依赖性。结论红花黄色素可保护H_2O_2诱导建立星形胶质细胞损伤,将可为红花黄色素的临床应用提供支持。     

去泛素化酶USP14调控H_2O_2诱导的H9c2细胞氧化应激损伤

目的:观察抑制泛素特异性蛋白酶14(ubiquitin-specific protease 14,USP14)的活性对H_2O_2诱导的H9c2细胞氧化应激损伤的影响。方法:体外培养H9c2心肌细胞,用H_2O_2(25μmol/L)处理2 h,建立心肌细胞氧化应激损伤模型。将细胞分为对照(control,CON)组、模型组(H_2O_2组)、USP14抑制剂IU1处理组(IU1组)和IU1处理后建模组(IU1+H_2O_2组)。MTS法检测H9c2心肌细胞活力;流式细胞术检测细胞内活性氧簇(ROS)的产生和细胞存活率;Western blot法检测丝裂原活化蛋白激酶家族相关蛋白的表达变化。结果:与CON组相比,H_2O_2组细胞活力、细胞存活率显著降低,细胞内ROS含量、Bax/Bcl-2、P53、p-ERK1/2、p-JNK和p-P38的蛋白水平显著增加(P0.05);与H_2O_2组比较,IU1+H_2O_2组细胞活力、细胞存活率显著增加,细胞内ROS含量、Bax/Bcl-2、P53、p-ERK1/2、p-JNK和p-P38蛋白水平显著降低(P0.05)。结论:抑制USP14活性可以减轻氧化应激条件下H9c2心肌细胞的损伤,其机制可能与抑制丝裂原活化蛋白激酶信号活化和下调凋亡相关蛋白有关。     

白桦脂酸对 H2O2 诱导的 PC12 神经细胞氧化损伤和细胞凋亡影响 #br#

目的探讨白桦脂酸对 H2O2诱导的 PC12 神经细胞氧化损伤和凋亡的影响。 方法PC12 神经细胞分成 Control、 Model (H2O2刺激)、 BA-L (1 μmol / L 的白桦脂酸和 H2O2刺激)、 BA-M (2 μmol / L 的白桦脂酸和 H2O2刺激)、 BA-H (4 μmol / L 的白桦脂酸和 H2O2 刺激)、 BA-H + PMA 组 (1 μmol / L 的白桦脂酸、H2O2 、 NF-κB 信号通路激活剂 PMA 刺激), CCK-8 方法分析细胞增殖活性变化, 流式细胞术分析细胞凋亡水平变化, Western 印迹分析细胞中 Bax、 Bcl-2、 P65 蛋白表达变化, 黄嘌呤氧化法检测 SOD 水平, 比色法检测 GSH-Px 水平、 硫代巴比妥酸法检测 MDA 水平、 CellROX Green 荧光法检测 ROS 水平。 结果与 Control 组比较, Model 组 PC12 神经细胞增殖活性降低, 细胞凋亡率升高, 细胞中 Bax 蛋白表达水平升高, Bcl-2蛋白表达水平降低, SOD、 GSH-Px 活性降低, MDA、 ROS 水平升高, P65 蛋白水平升高。 与 Model 组比较,BA-L、 BA-M、 BA-H 组 PC12 神经细胞增殖活性逐渐升高, 细胞凋亡率逐渐降低, 细胞中 Bax 蛋白表达逐渐减少, Bcl-2 蛋白表达逐渐增加, SOD、 GSH-Px 活性逐渐升高, MDA、 ROS 水平逐渐降低, P65 蛋白水平逐渐降低。 与 BA-H 组比较, BA-H + PMA 组 C12 神经细胞增殖活性降低, 细胞凋亡率升高, 细胞中 Bax、P65 蛋白表达增多, Bcl-2 蛋白表达减少, SOD、 GSH-Px 活性降低, MDA、 ROS 水平升高。 结论白桦脂酸通过下调 NF-κB 信号抑制 H2O2诱导的 PC12 神经细胞氧化损伤和细胞凋亡。     

连翘苷通过APPL1对缺氧/复氧诱导心肌细胞损伤的影响

目的:研究连翘苷通过转接蛋白APPL1对缺氧/复氧(H/R)诱导的心肌细胞氧化应激和凋亡的影响。方法:将大鼠心肌细胞H9C2分为Con组、H/R组、H/R+连翘苷低剂量组、H/R+连翘苷中剂量组、H/R+连翘苷高剂量组、H/R+pcDNA组、H/R+pcDNA-APPL1组、H/R+连翘苷+si-NC组和H/R+连翘苷+si-APPL1组。ELISA检测丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性和谷胱甘肽过氧化物酶(GSH-Px)活性;流式细胞术检测心肌细胞凋亡率;蛋白质印迹法(Western blot)检测B细胞淋巴瘤/白血病-2(Bcl-2)、Bcl-2相关X蛋白(Bax)及APPL1蛋白;实时荧光定量PCR(qPCR)检测APPL1 mRNA表达。采用单因素方差分析和多重两两比较t检验进行统计学分析。结果:与Con组比较,H/R组心肌细胞MDA含量、凋亡率和Bax蛋白表达明显增加,SOD、GSH-Px活性、Bcl-2蛋白水平、APPL1 mRNA和蛋白表达显著降低(均P<0.01)。与H/R组比较,H/R+连翘苷各剂量组心肌细胞MDA含量、凋亡率、Bax蛋白表达明显减少,SOD、GSH-Px活性、Bcl-2蛋白水平、APPL1 mRNA和蛋白表达显著升高(均P<0.01)。连翘苷各剂量组APPL1 mRNA和蛋白表达高于H/R组(P<0.01)。与H/R+pcDNA组比较,H/R+pcDNA-APPL1组心肌细胞SOD和GSH-Px活性、Bcl-2蛋白水平显著升高,MDA含量、凋亡率、Bax蛋白表达显著降低(均P<0.01)。H/R+连翘苷+si-APPL1组与H/R+连翘苷+si-NC组比较,心肌细胞中MDA含量、凋亡率、Bax蛋白显著升高,SOD和GSH-Px活性、Bcl-2蛋白水平明显降低(P<0.05)。结论:连翘苷可能通过提高H/R心肌细胞的APPL1表达实现对H/R心肌细胞损伤的治疗作用。     

靶向TLR4 的siRNA 慢病毒感染减少过氧化氢诱导的心肌H9C2 细胞凋亡及氧化损伤

目的:研究沉默TLR4对过氧化氢(H_2O_2)诱导的心肌H9C2细胞凋亡及氧化损伤的影响。方法:用H_2O_2处理心肌H9C2细胞,qRT-PCR和Western blot检测细胞中Toll样受体4(TLR4) mRNA和蛋白水平。用siRNA TLR4慢病毒感染心肌H9C2细胞,H_2O_2诱导以后,流式细胞术检测细胞凋亡,Western blot检测细胞中凋亡蛋白Bcl-2相关X蛋白(Bax)和剪切型Caspase-3(Cleaved Caspase-3)水平,硫代巴比妥酸法检测细胞中丙二醛(MDA)水平,黄嘌呤氧化法检测细胞中超氧化物歧化酶(SOD)活性,二硝基苯肼显色法检测上清中乳酸脱氢酶(LDH)含量,二氯二氢荧光素-乙酰乙酸酯(DCFH-DA)法检测活性氧(ROS)水平,ELISA法检测培养液上清中TNF-α、IL-6水平。结果:H_2O_2诱导处理以后的心肌H9C2细胞中TLR4mRNA和蛋白水平均明显高于未经诱导的心肌H9C2细胞(P0. 05)。siRNA TLR4慢病毒感染后可以降低心肌H9C2细胞中TLR4 mRNA和蛋白水平。H_2O_2诱导后的心肌H9C2细胞凋亡率升高,Bax和Cleaved Caspase-3蛋白水平升高,细胞中SOD活性降低,MDA水平升高,ROS水平也升高,同时细胞培养液中LDH水平升高,细胞分泌的TNF-α、IL-6增多,与未经诱导的心肌H9C2细胞比较,差异有统计学意义(P0. 05)。敲低TLR4后的心肌H9C2细胞经H_2O_2诱导处理以后,细胞凋亡率降低,细胞中Bax和Cleaved Caspase-3蛋白水平降低,细胞中SOD活性升高,MDA水平降低,ROS水平也降低,同时细胞培养液中LDH水平降低,细胞分泌的TNF-α、IL-6减少,与单纯经H_2O_2诱导处理的心肌H9C2细胞比较,差异有统计学意义(P0. 05)。结论:沉默TLR4减弱H_2O_2诱导的心肌H9C2细胞凋亡及氧化损伤,减少细胞中ROS的聚集,减少心肌H9C2细胞分泌炎症因子。     

丙泊酚减轻H2O2诱导的心肌细胞系H9C2损伤

目的研究丙泊酚对过氧化氢(H_2O_2)诱导的心肌细胞系H9C2损伤及活性氧(ROS)水平的影响。方法将心肌细胞分成对照组、H_2O_2处理组和15、30和60μmol/L丙泊酚干预组。MTT检测细胞活力;二硝基苯肼显色法检测乳酸脱氢酶(LDH)漏出率;流式细胞计量术检测细胞凋亡;Western blot检测细胞中激活型caspase-3(cleaved caspase-3)、胞质和线粒体中细胞色素C(cytochrome C)蛋白水平;黄嘌呤氧化法检测超氧化物歧化酶(SOD)活性;钼酸铵法检测过氧化氢酶(CAT)活性;二硫代二硝基苯甲酸法检测谷胱甘肽过氧化物酶(GSH-Px)活性;硫代巴比妥酸法检测丙二醛(MDA)含量;二氯二氢荧光素-乙酰乙酸酯法检测ROS活性;JC-1法检测线粒体膜电位。结果与对照组比较,H_2O_2处理组细胞活力降低;LDH漏出率和凋亡率升高;cleaved caspase-3蛋白水平及胞质中cytochrome C水平升高;线粒体cytochrome C水平降低;SOD、CAT和GSH-Px活性降低;MDA及ROS含量升高;线粒体膜电位下降(P0.05)。与H_2O_2处理组比较,15、30和60μmol/L丙泊酚组细胞活性升高;LDH漏出率降低;凋亡率和cleaved caspase-3水平降低;胞质中cytochrome C蛋白水平减少;线粒体中cytochrome C水平升高;细胞SOD活性、CAT活性和GSH-Px活性升高;MDA含量和ROS含量降低;线粒体膜电位升高(P0.05)。结论丙泊酚可以减轻H_2O_2诱导的心肌细胞损伤,减少细胞凋亡并降低细胞ROS水平。     

槲皮素对INH诱导的大鼠肝损伤及肝组织Bcl-2和Bax表达的影响

目的探讨槲皮素对异烟肼(INH)致大鼠肝损伤的保护作用。方法将动物随机分为正常对照组、INH组、槲皮素低剂量组、槲皮素高剂量组,灌胃染毒,每天1次,14d后测定大鼠血清中天冬氨酸氨基转移酶(AST)和丙氨酸氨基转移酶(ALT)的活性,肝匀浆中丙二醛(MDA)含量、谷胱甘肽过氧化物酶(GSH-Px)和超氧化物歧化酶(SOD)活性,用Westernblot法检测肝组织中Bcl-2和Bax蛋白的表达。结果与正常对照组比较,INH组大鼠血清AST和ALT的活性增强,肝组织的MDA含量升高,SOD和GSH-Px活性降低,Bcl-2蛋白表达减少,而Bax蛋白表达增加;高剂量槲皮素可减轻INH所致的损伤。结论槲皮素对INH所致的大鼠肝损伤具有保护作用,可能与其抗脂质过氧化作用及调节凋亡相关蛋白Bcl-2和Bax的表达有关。     

地佐辛通过上调miR-204-3p减轻LPS诱导的心肌细胞H9C2损伤北大核心CSCD

目的:探讨地佐辛对脂多糖(LPS)诱导的心肌细胞损伤的影响及可能机制。方法:体外培养心肌细胞H9C2,分为Con组、LPS组、不同剂量(4、8、16μmol/L)地佐辛组、16μmol/L地佐辛+anti-miR-NC组和16μmol/L地佐辛+anti-miR-204-3p组,CCK-8检测细胞增殖,流式细胞仪检测细胞凋亡,Western blot检测CyclinD1、p21、Bcl-2和Bax蛋白表达,试剂盒检测细胞培养上清中LDH水平及细胞中MDA、SOD和GSH-Px水平,RT-qPCR检测细胞miR-204-3p表达。结果:与Con组比较,LPS组H9C2细胞OD值、CyclinD1和Bcl-2蛋白表达、SOD和GSH-Px活性及miR-204-3p表达降低(P<0.05),细胞凋亡率、p21和Bax蛋白表达及MDA和LDH含量升高(P<0.05)。与LPS组比较,不同剂量(4、8、16μmol/L)地佐辛组H9C2细胞OD值、CyclinD1和Bcl-2蛋白表达、SOD和GSH-Px活性及miR-204-3p表达升高(P<0.05),细胞凋亡率、p21和Bax蛋白表达及MDA和LDH含量降低(P<0.05),且呈剂量依赖性。与16μmol/L地佐辛+anti-miR-NC组比较,16μmol/L地佐辛+anti-miR-204-3p组H9C2细胞OD值、CyclinD1和Bcl-2蛋白表达、SOD和GSH-Px活性及miR-204-3p表达降低(P<0.05),细胞凋亡率、p21和Bax蛋白表达及MDA和LDH含量升高(P<0.05)。结论:地佐辛可能通过上调miR-204-3p表达促进LPS诱导的心肌细胞H9C2增殖,并抑制H9C2细胞凋亡和氧化应激,减轻LPS诱导的H9C2细胞损伤。     

维生素E在体内外具有抗氧化作用

目的探讨维生素E在体内外的应激损伤。方法体外实验:人肝RBL细胞系根据H_2O_2损伤及损伤前后给予维生素E分为4组,对照组(C)、H_2O_2损伤组(Ec)、H_2O_2损伤前(Eb)及后(Ea)给维生素E组;体内实验:将20只清洁级雄性Wistar大鼠分为对照组和大及小剂量维生素E组,每天进行一次35和15 mg/kg溶液2 m L灌胃,连续3 d。体外实验应用MTT和TUNEL法检测细胞存活率和凋亡率,免疫印迹和免疫组化方法检测细胞中NF-κB、Hsp-70、Bcl-2、Bax及caspase-3的表达水平;体内实验应用生化法检测3和6 d后血浆内T-AOC、SOD、GSH和MDA的水平。结果 H_2O_2损伤组(Ec)细胞凋亡率增加(P0.01),细胞内Bax、Hsp-70、NF-κB及caspase-3显著升高(P0.01),而Bcl-2显著下降(P0.01),维生素E干预后能显著缓解上述变化(P0.01),H_2O_2损伤前干预效果优于后干预。灌胃后3 d血浆中T-AOC、SOD、GSH的水平增高,MDA降低(P0.01),6 d后其相关指标变化更加显著(P0.05)。结论维生素E可通过调节人肝RBL细胞相关蛋白表达水平和Wistar大鼠血浆中抗氧化酶体系而发挥抗氧化作用。     

脯氨酰异构酶1 沉默抑制缺氧/ 复氧H9c2 心肌细胞凋亡

目的:肽基脯氨酰顺反异构酶1(Pin1)在心血管疾病发病过程中发挥重要作用,本研究检测RNA 干扰沉默Pin1 对缺氧/ 复氧诱导的大鼠胚胎心肌细胞H9c2 凋亡的影响及机制。方法:体外培养大鼠H9c2 细胞,建立缺氧/ 复氧损伤模型,模拟体内缺血再灌注损伤;RT-qPCR 和Western blot 法检测Pin1 的表达;将细胞分为空白对照组、缺氧/ 复氧组、缺氧/ 复氧组+转染Pin1 siRNA 组、缺氧/ 复氧组+转染scramble siRNA 组;MTT 法测H9c2 细胞存活率;用流式细胞术Annexin V/ PI 双染法检测细胞凋亡率;用Western blot 法检测H9c2 细胞Bax 和Bcl-2 蛋白表达;生化法检测Caspase-3 的活性水平。结果:Pin1 在缺氧/ 复氧H9c2 细胞中呈现高表达;转染Pin1 siRNA 后,Pin1 的mRNA 和蛋白表达水平均显著降低(P<0.05);与缺氧/ 复氧组比较,Pin1 siRNA 组的细胞存活率增加,凋亡率降低,Bcl-2 蛋白表达升高,Bax 蛋白表达降低,Bcl-2/ Bax 升高,Caspase-3 活性降低,差异均有统计学意义(P<0.05)。结论:Pin1 下调可减少缺氧/ 复氧诱导的心肌细胞凋亡,可能是通过上调Bcl-2,下调Bax 蛋白表达,降低Caspase-3 活性而发挥作用。     

CaO-MgO-P_2O_5-SiO_2-CaF_2系统自硬性玻璃的研究

为研究钙离子、镁离子在体内环境中对自硬性玻璃结晶行为的影响,为自硬性生物活性玻璃的临床应用提供依据,本文设计了CaO-P2O5-SiO2-CaF2(Ca-glass)和CaO-MgO-P2O5-SiO2-CaF2(CaMg-glass)系统玻璃并使用模拟体液(simulated body flu id,SBF)进行了研究。首先采用磷酸氢二氨[(NH4)2HPO4]/[NH4H2PO4]硬化液与Ca-glass、CaMg-glass制成硬化体,然后使用X射线衍射(XRD)、扫描电镜(SEM)、失重、力学分析等方法,研究硬化体在SBF中的结晶性、降解性和力学性能。实验结果表明,玻璃粉末与磷酸铵缓冲溶液反应形成了磷酸铵钙[(NH4)2.Ca(HPO4)2.H2O]硬化体。硬化体经过SBF浸泡,Ca-glass系统硬化体中部分磷酸铵钙转化成羟基磷灰石,而CaMg-glass系统硬化体仍然为磷酸铵钙。Ca-glass与CaMg-glass硬化体在SBF中浸泡28天分别降解19.4%和31.3%,抗压强度分别为93.14MPa和64.52MPa。镁离子的歧化作用是导致Ca-glass、CaMg-glass硬化体结晶性能、降解性能以及力学性能差别的主要原因。     

2-Perbromomethyl-2-oxazoline: a novel trifunctional initiator for the ring-opening polymerization of 2-methyl-2-oxazoline

Polymerization of 2-methyl-2-oxazoline was carried out using a trifunctional initiator, 2-perbromomethyl-2-oxazoline. The degree of polymerization (DP) of the resulting polymer was very close to the feed mole ratio of the monomer to initiator. The number-average molecular weight M?_n increased linearly with conversion, indicating the living nature of the propagating chain end. ¹H NMR and end-group analyses results are consistent with the proposal that the polymer possesses a star-shaped structure.     

Corticosteroid-interleukin 2 interactions: inhibition of binding of interleukin 2 to interleukin 2 receptors.

PHA activated human peripheral blood mononuclear cells (MNC) were incubated with human interleukin 2 (IL-2) in the absence or in the presence of 10(-6)-10(-9) M hydrocortisone (HC). HC suppressed the proliferative response of the activated MNC to highly purified human leucocyte IL-2 in a dose dependent manner. This suppression was in full accordance with an inhibition of the IL-2 binding capacity, whereby the high affinity binding sites were reduced by 85%, while the low affinity sites were less affected. The mechanism by which HC inhibits the binding of IL-2 is still unknown. Evidence is presented that HC binds only weakly to IL-2. We conclude that HC interferes with the IL-2 binding by modulating the binding and/or signal processing function of the IL-2 receptor.     

13C NMR spectroscopy of 2-formamido-2-methylpropyl acrylate and poly(2-formamido-2-methylpropyl acrylate)

The synthesis and characterization of 2-formamido-2-methylpropyl acrylate (FMPA) is reported. ¹³C NMR spectra of FMPA in CDCl₃, CD₃OD, DMSO-d₆, DMF-d₇, and D₂O exhibit two pairs of lines for all seven carbon atoms at room temperature; the ratio of the two conformers varies moderately with solvent (21 : 79 to 41 : 59). The conformers are believed to involve strong internal hydrogen bonding which is not completely broken even by the addition of trifluoroacetic acid to CDCl₃ (1/1, v/v). However, the pairs of lines coalesce in turn as the temperature is raised to 120°C in DMSO-d₆. FMPA was polymerized at 35°C in DMF and CHCl₃, using a free radical initiator and the polymer was characterized by ¹³C NMR spectroscopy.     

Isolation of a novel KIR2DL3-specific mAb: comparative analysis of the surface distribution and function of KIR2DL2, KIR2DL3 and KIR2DS2

In recent years an increasing number of sequences coding for new KIRs have been described. However, the limited availability of mAbs with unique KIR specificities has hindered an exhaustive assessment of their actual function, HLA-specificity, expression at the cell surface and distribution in different cell populations. In this study we report the generation of a novel mAb (ECM41) specific for KIR2DL3 molecules. By the use of cell transfectants expressing one or other KIR we show that this reagent allows discrimination of KIR2DL3 from other GL183 mAb-reactive molecules such as KIR2DL2 and KIR2DS2. Moreover we show that this novel mAb can be used to assess the surface expression and distribution of KIR2DL3 in different polyclonal NK populations and in NK cell clones. Along this line, we were able to analyze the HLA class I specificity of NK clones expressing either KIR2DL3 or KIR2DL2, two inhibitory receptors that were so far serologically undistinguishable. Finally, the combined use of GL183 and ECM41 mAbs in redirected killing assays allowed us to investigate the functional outcome of the simultaneous engagement of KIR2DL3 and KIR2DS2 in NK cell clones co-expressing KIRs that display opposite (inhibitory vs activating) function.     

肌肽减轻H_2O_2诱导的N2a细胞损伤

目的探究肌肽对H2O2诱导的N2a细胞损伤的保护作用及其机制。方法将N2a细胞分为对照组、损伤组(给予H2O2)和肌肽保护组(预先加入肌肽)。用相差显微镜观察了细胞形态,用免疫荧光染色和免疫印迹实验检测细胞AKT1和FAS-L的蛋白表达。结果肌肽显著增加了N2a细胞增殖能力(P0.05);与对照组比较,H2O2损伤组细胞形态发生明显改变,细胞皱缩,胞膜变厚并出现发泡现象;而肌肽保护组细胞形态较损伤组明显改善;免疫荧光染色和免疫印迹实验显示,损伤组AKT1的表达显著低于对照组,FAS-L的表达显著高于对照组。而肌肽保护组AKT1的表达显著高于对照组,FAS-L的表达显著低于对照组(P0.05)。结论肌肽能够减轻N2a细胞对H2O2诱导的细胞损伤。     

An apparent KIR2DS2-negative KIR2DL2-positive genotype discloses the novel allele KIR2DS2*00104

KIR2DS2*00104 lacks a distinctive synonymous substitution of KIR2DS2 in nucleotide 418 that affects KIR genotyping.     

Synthesis and copolymerization of macromonomers based on 2-nonyl- and 2-phenyl-2-oxazoline

Several macromonomers were prepared by cationic ring-opening polymerization of 2-nonyl- and 2-phenyl-2-oxazoline using different techniques of functionalization. Introduction of the unsaturated functional group directly via a suitable termination agent proved to be superior to the use of a phenol-functionalized initiator and to the introduction of hydroxyl end groups via hydrolysis of the reactive cationic chain end and subsequent esterification with methacryloyl chloride. The macromonomers were characterized by spectroscopic techniques as well as GPC. One of the 4-vinylbenzyl-terminated macromonomers was copolymerized with MMA in different ratios. The copolymerization parameter r₁ was determined to be 0.75. The resulting graft copolymers were characterized regarding number of grafts per chain, molar mass, and glass transition temperature.     

NDRG2对肝癌细胞HepG2凋亡的诱导作用

目的：探讨NDRG2对肝癌细胞HepG2凋亡的诱导作用。方法：用RT-PCR获取NDRG2基因。测序判断正确后，将其克隆入含绿色荧光蛋白(GFP)基因的真核表达载体pIRES2-EGFP中，并转染NDRG2表达阴性的HepG2细胞。用光镜观察转染细胞的形态变化；荧光显微镜观察NDRG2蛋白的定位；流式细胞仪分析细胞周期的改变；透射电镜进一步观察细胞超微结构的改变。结果：获得了NDRG2基因，成功地构建了pIRES2-EGFP-NDRG2真核表达载体。转染HepG2细胞后，细胞生长受抑，结构破坏并死亡。荧光显微镜观察到NDRG2在胞质中表达，流式细胞仪检测出现G1期阻滞和凋亡峰，透射电镜观察到典型的细胞凋亡特征。结论：NDRG2基因具有诱导HepG2细胞凋亡的作用，其机制有待进一步研究。     

Synthesis and polymerization of 2-cyano-2-methyltrimethylene carbonate

2-Cyano -methyltrimethylene carbonate (CMTC, 2 ) was synthesized starting from 2-methylacrolein (6), propionaldehyde (8) or 2-hydroxymethyl-2-methyl-1,3-propanediol (9). A key position in this synthesis is held by 2,2-bis(hydroxymethyl)propionitrile ( 3 ), which in a first step, is reacted — in conjunction with 2,2-dimethyl-1,3-propanediol ( 20 0) — with diphenyl carbonate ( 17 ) to result in a statistical copolycarbonate. Ring-closing depolymerization of this polymer, with a catalyst based on tin, yields in a second step the title monomer, CMTC (2), along with 2,2-dimethyltrimethylene carbonate (DTC, 1b ). Separation of the two monomers can be achieved by selective solubilization of the latter in toluene. Polymerization of CMTC is performed preferentially by using weak nucleophiles as initiators, such as Et₂AlOEt, Al(O-secBu)₃ or MgBu₂, since strong nucleophiles such as BuLi or ZnEt₂ tend to give side reactions with the cyano group. Copolymerization of CMTC with DTC results in statistical copolymers. With Et₂AlOEt as initiator copolymers with Bernoulli statistics are obtained, with a ratio of diads DTC/DTC : (DTC/CMTC + CMTC/DTC) : CMTC/CMTC equal to 1:2:1 for equimolar feed composition. With MgBu₂ as initiator and the same feed composition, a copolymer with the diad ratio 1:5:1 is obtained. Poly(CMTC) is a crystalline polymer with a melting point of 132.9°C and a glass transition temperature of 68.8 °C.