雷帕霉素脂质体对ox-LDL诱导的血管平滑肌细胞迁移的抑制作用

目的]探讨雷帕霉素脂质体(RL)对氧化型低密度脂蛋白(ox-LDL)诱导的人主动脉血管平滑肌细胞(HA-VSMC)迁移的影响及其与S100钙结合白蛋白A4(S100A4)相关的作用机制。 [方法]使用敲低S100A4基因的慢病毒转染HA-VSMC,随后加入嘌呤霉素筛选S100A4基因敲低的稳定株。50 mg/L ox-LDL处理HA-VSMC,加入不同剂量的RL(3、6及12 mg/L),观察处理前后对细胞迁移的影响。采用细胞划痕法、Transwell实验检测细胞迁移,Western blot检测S100A4、磷酸化磷脂酰肌醇3激酶(p-PI3K)、磷酸化蛋白激酶B(p-Akt)、磷酸化哺乳动物雷帕霉素靶蛋白(p-mTOR)、Ⅰ型胶原蛋白(COLⅠ)、波形蛋白的表达。 [结果]ox-LDL处理细胞48 h后,与空白对照组相比,S100A4、p-PI3K、p-Akt、p-mTOR、COLⅠ及波形蛋白的表达明显升高(P＜0.05),细胞迁移速度明显加快(P＜0.05)。与ox-LDL组相比,不同剂量的RL处理48 h后显著抑制S100A4、p-PI3K、p-Akt、p-mTOR、COLⅠ及波形蛋白的表达并显著抑制细胞迁移(P＜0.05),其中6 mg/L、12 mg/L RL的抑制作用更明显(P＜0.05)。敲低S100A4基因后细胞迁移率显著降低(P＜0.05)。 [结论]RL能显著抑制ox-LDL诱导的HA-VSMC迁移,可能与RL下调S100A4、p-PI3K、p-Akt、p-mTOR、COLⅠ及波形蛋白的表达相关。     

替米沙坦诱导大鼠肝细胞自噬促进肝脏胆固醇代谢的机制研究

目的探讨替米沙坦诱导大鼠肝细胞自噬对肝脏胆固醇代谢的影响及作用机制。方法将肝脏原代细胞分为正常对照组(Con)、替米沙坦1μmol/L组(Tel 1组)、替米沙坦3μmol/L组(Tel 3组)、替米沙坦10μmol/L组(Tel 10组)、替米沙坦10μmol/L联合PPARγ抑制剂GW 9662组(Tel+G组)。Tel 1、Tel 3、Tel 10组分别按1、3、10μmol/L浓度加入替米沙坦,Tel+G组加入10μmol/L替米沙坦及PPARγ抑制剂GW9662,培养24 h。检测肝细胞胆固醇浓度,Western blot法检测微管相关蛋白轻链3(LC3)、自噬蛋白区域(Beclin-1)、腺苷酸活化蛋白激酶(AMPK)、雷帕霉素靶分子(mTOR)表达水平。结果 Tel 3、Tel 10组胆固醇水平低于Con、Tel 1组(P<0.05)。Tel 1、Tel 3、Tel 10组LC3Ⅱ/Ⅰ比值、Beclin-1蛋白水平依次升高(P<0.05)。与Con、Tel 1组比较,Tel 3、Tel 10组p-AMPK/AMPK蛋白比值升高(P<0.05),p-mTOR/mTOR蛋白比值降低(P<0.05)。与Tel 10组比较,Tel+G组胆固醇水平、p-mTOR/mTOR蛋白比值升高(P<0.05),LC3II/I比值、p-AMPK/AMPK蛋白水平降低(P<0.05)。结论替米沙坦可通过诱导大鼠肝细胞自噬影响肝脏细胞胆固醇代谢,其机制可能与激活AMPK/mTOR途径和上调PPARγ有关。     

Quercetin对人气道平滑肌细胞增殖和迁移的影响及机制

目的 体外培养人气道平滑肌细胞(human airway smooth muscle cells,HASMCs),探讨槲皮素(Quercetin,Que)对血小板源性生长因子BB(PDGF-BB)刺激的HASMCs增殖和迁移的影响及其机制.方法体外培养HASMCs,分为六组；对照组、PdGF-BB组、Que与PDGF-BB联合干预组、Que组、U0126组、U0126与PDGF-BB联合干预组.四甲基偶氮唑蓝(MTT)微量比色法测定HASMCs增殖,transwell法观察细胞迁移,Western blot法检测ERK的磷酸化及Cyclin D1表达水平.结果 与对照组相比,PDGF-BB(20μg/L)显著诱导HASMCs增殖和迁移(P＜0.05),Que(20～80μmol/L)呈浓度依赖性抑制PDGF-BB诱导的HASMCs的增殖和迁移(P＜0.05).PDGF-BB组ERK磷酸化及Cyclin D1 表达水平较对照组明显增高(P＜0.05).Que(80μmol/L)及PDGF-BB干预组其表达量低于PDGF-BB组,此抑制作用与ERK特异性拮抗剂U0126作用相当(P＞0.05).结论 Que抑制PDGF-BB诱导的HASMCs的增殖和迁移,可能是通过调节ERK/Cyelin D1通路起作用.     

罗格列酮对血管紧张素Ⅱ诱导血管平滑肌细胞增殖的影响

目的 探讨罗格列酮对血管紧张素Ⅱ诱导血管平滑肌细胞增殖的影响及可能的机制.方法 原代培养大鼠血管平滑肌细胞,取第4～8代细胞进行实验.用终浓度为1 μmol/L血管紧张素Ⅱ诱导6 h,随机分成对照组(含10% FBS的DMEM培养基)、1 μmol/L血管紧张素Ⅱ组、不同浓度罗格列酮(20、30、40及50μmol/L) 干预组,30 μmol/L罗格列酮干预不同时间组 (6、12、18及24 h).分别采用MTT和流式细胞术观察血管平滑肌细胞增殖和增殖周期的变化;逆转录聚合酶链反应和免疫印迹法测定不同干预条件下血管平滑肌细胞血管紧张素Ⅱ2型受体mRNA和蛋白的表达水平.结果 血管紧张素Ⅱ组吸光值明显高于对照组(P<0.01),20、30、40及50μmol/L罗格列酮干预12 h及30μmol/L 罗格列酮干预6、12、18及24 h后,吸光值明显降低(P<0.05或P<0.01);血管紧张素Ⅱ组增殖指数和S期细胞分数明显高于对照组(P<0.01).随着罗格列酮干预浓度的增加或干预时间的延长,增殖指数、S期细胞分数及处于S期分数均明显下降(P<0.05或P<0.01).与血管紧张素Ⅱ组相比,不同浓度(20、30及50μmol/L)罗格列酮干预12 h及同一浓度(30μmol/L)干预不同时间(6、12及24 h)显著升高血管紧张素Ⅱ2型受体mRNA和蛋白的表达(P<0.05或P<0.01).结论 罗格列酮至少部分通过上调血管紧张素Ⅱ2型受体表达,阻止血管平滑肌细胞从G0/G1期向S期、G2/M期转化,从而抑制血管紧张素Ⅱ诱导血管平滑肌细胞的增殖、迁移,发挥血管保护作用.     

黄芪多糖和水蛭素联合干预对巨噬细胞脂质积聚的影响及其机制

目的]明确黄芪多糖和水蛭素联合干预对氧化型低密度脂蛋白(ox-LDL)诱导的巨噬细胞内脂质积聚、线粒体膜电位和细胞凋亡相关蛋白的影响。 [方法]采用100 mg/L ox-LDL孵育RAW264.7细胞24 h建立泡沫细胞模型,采用优化浓度的黄芪多糖和水蛭素联合干预,设立对照组、模型组、黄芪多糖组、水蛭素组和二者联合干预组。采用油红O染色和氧化酶法检测ox-LDL诱导的巨噬细胞内胆固醇含量,流式细胞仪检测巨噬细胞早期凋亡率、晚期凋亡率和总凋亡率,激光共聚焦显微镜检测细胞线粒体膜电位的变化,Western blot检测抗凋亡蛋白Bcl-2及促凋亡蛋白Caspase-3和Bax的表达水平。 [结果]与水蛭素组、黄芪多糖组相比,黄芪多糖和水蛭素联合干预组细胞内胆固醇含量降低更明显(P＜0.05)。与模型组相比,黄芪多糖＋水蛭素联合干预组可显著降低ox-LDL诱导的巨噬细胞早期凋亡率和总凋亡率(P＜0.01)、上调巨噬细胞线粒体膜电位(P＜0.01),并显著降低Caspase-3和Bax蛋白表达量,升高Bcl-2蛋白表达量(P＜0.05)。 [结论]黄芪多糖和水蛭素联合干预可降低巨噬细胞内脂质积聚,且优于单独用药干预,两者联合干预可降低ox-LDL诱导的巨噬细胞凋亡率,其作用机制可能与调控线粒体膜电位和改善促凋亡蛋白Caspase-3、Bax以及抗凋亡蛋白Bcl-2的表达有关。     

剪切修复基因D通过下调mTOR/LOX-1抑制ox-LDL诱导的人脐静脉平滑肌细胞增殖

[目的]探讨剪切修复基因D(XPD)在氧化型低密度脂蛋白(ox-LDL)促血管平滑肌细胞增殖中的作用及分子机制。[方法]将重组质粒pEGFP-N2/XPD利用脂质体转染人脐静脉平滑肌细胞(HUVSMC),沉默哺乳动物雷帕霉素靶蛋白(mTOR)基因,用MTT、EdU法测定各组细胞的增殖;流式细胞仪检测各组凋亡率;利用Western blot检测XPD、血凝素样氧化型低密度脂蛋白受体1(LOX-1)、mTOR、p-mTOR、Bcl-2及Bax的表达。[结果]与对照组比较,ox-LDL组XPD表达明显下调(P<0.05),Bax蛋白表达下调(P<0.05),Bcl-2蛋白、Bcl-2/Bax、mTOR磷酸化活性及LOX-1蛋白表达升高(P<0.05);MTT、BdU结果显示,ox-LDL组细胞增殖较对照组上调(P<0.05)。转染pEGFP-N2/XPD重组质粒能上调Bax蛋白表达(P<0.05)并抑制Bcl-2蛋白、mTOR磷酸化活性及LOX-1蛋白表达(P<0.05),Bcl-2/Bax比值下调(P<0.05);流式细胞仪检测结果显示,转染pEG...     

H2S拮抗HUVEC衰老与促进SIRT1巯基化和减少FOXO1乙酰化有关

目的]探讨沉默信息调节因子1(SIRT1)/叉头转录因子O1(FOXO1)在H₂S拮抗H₂O₂诱导内皮细胞衰老过程中的作用。 [方法]建立内皮细胞衰老模型,通过衰老相关β-半乳糖苷酶(SA-β-gal)染色在光学显微镜下观察到的蓝染细胞数(即衰老细胞)计算阳性细胞率。采用Western blot检测细胞P21、P53、纤溶酶原激活物抑制剂1(PAI-1)、叉头转录因子O1(FOXO1)、乙酰化FOXO1(ac-FOXO1)、锰超氧化物歧化酶(MnSOD)及过氧化氢酶的蛋白表达水平,采用生物素转换法测定S-巯基化SIRT1的表达,采用活性氧(ROS)检测定量评估细胞内ROS水平。 [结果]经100 μmol/L H₂O₂处理可显著提高SA-β-gal染色阳性细胞率和P21、P53、PAI-1的蛋白表达,提示衰老细胞模型成功建立,而100 μmol/L NaHS可明显拮抗这一作用,SA-β-gal染色阳性细胞数明显下降(P＜0.01),P21、P53、PAI-1的蛋白表达显著降低(P＜0.01)。与对照组相比,H₂O₂组SIRT1、FOXO1、ac-FOXO1、MnSOD及过氧化氢酶的蛋白表达显著降低(P＜0.05或P＜0.01),ac-FOXO1/FOXO1比值显著增加(P＜0.01),ROS水平明显升高(P＜0.01)。与H₂O₂组相比,NaHS＋H₂O₂组SIRT1、S-巯基化SIRT1、FOXO1、ac-FOXO1、MnSOD及过氧化氢酶的蛋白表达显著升高((P＜0.05或P＜0.01),ac-FOXO1/FOXO1比值显著下降(P＜0.01),ROS水平明显降低(P＜0.05)。 [结论]H₂S可拮抗H₂O₂诱导的HUVEC衰老,其机制与促进SIRT1巯基化和减少FOXO1乙酰化有关。     

β-榄香烯对血管紧张素Ⅱ诱导的HSC T6细胞增殖和迁移及RhoA的影响

目的 探讨β榄香烯对血管紧张素(ANG)Ⅱ诱导的肝星状细胞(HSC)增殖迁移及RhoA信号的影响. 方法体外培养HSC,应用ANGⅡ诱导HSC增殖迁移,采用四甲基偶氮唑盐法测定细胞增殖,Transwell小室检测细胞迁移,RT-PCR检测RhoA mRNA,Western blot检测RhoA蛋白.结果 1、2、4、8、10 μmol/L ANGⅡ组A490分别为0.129±0.004、0.143±0.016、0.166±0.012、0.183±0.004、0.283+0.014,与空白对照组(0.110+0.002)比较,ANGⅡ可显著促进HSC增殖,F=112.640,P<0.01;10、8、4 μmol/L的ANG Ⅱ可显著诱导HSC迁移,细胞迁移数分别为每高倍视野(17.40±2.07)、(12.60±1.14)、(9.00±1.58)个,与空白对照组[(1.60±0.55)个]比较,F=117.496,P<0.01.10、5、2.5mg/L的β榄香烯组A490分别为0.076±0.005、0.086±0.003、0.105±0.038,显著低于4μmol/L ANG Ⅱ组,F=95.706,P<0.01;10、5、2.5 mg/L的β-榄香烯组细胞迁移数分别为每高倍视野(1.33±0.58),(2.67±0.58)、(1.67±0.58)个,与4μmol/L ANGⅡ组比较,F=55.600,P<0.01,差异有统计学意义.4 μmol/L ANGⅡ组可显著诱导RhoA蛋白(相对表达量0.975±0.001)及mRNA(相对表达量0.951±0.045)表达,经10、5、2.5 mg/L的β-榄香烯作用后RhoA蛋白相对表达量分别为0.077±0.032、0.538 ± 0.026、0.701±0.078,RhoA mRNA相对表达量分别为0.734±0.038、0.845±0.036、0.881±0.027,较4 μ mol/L ANG Ⅱ组显著下降,F值分别为217.119,18.010,P值均<0.01.结论 ANG Ⅱ可显著诱导HSC增殖、辽移,随剂量的增加诱导作用加强,β-榄香烯可有效抑制ANG Ⅱ诱导的HSC增殖迁移,并能抑制HSC表达RhoA.     

血管紧张素Ⅱ对肝星状细胞迁移和增殖的影响

目的探讨血管紧张素Ⅱ(ANGⅡ)对肝星状细胞(HSC)增殖、迁移活性的影响.方法体外培养HSC,在不同浓度的ANGⅡ作用下,观察HSCs生长情况并绘制生长曲线,采用MTT法测定细胞增殖、Transwell小室检测细胞迁移.结果1,2,4,8,10 μmol/LANGⅡ可显著促进HSC增殖,与空白对照组相比有显著差异(F=2.305,P＜0.05;F=4.003,6.833,8.855,21.066,P＜0.01).随作用浓度的增加,细胞增殖活性显著提高,相关分析显示呈正相关(r=0.917,P＜0.01).10,8,4 μmol/L的ANGⅡ可显著诱导HSC迁移,与空白对照组相比差异显著(F=22.084,15.155,10.392,P＜0.01).随ANGⅡ浓度的增加,细胞迁移率显著升高,相关分析显示呈正相关(r=0.952,P＜0.01).结论ANGⅡ可显著诱导HSC增殖与迁移,并随剂量的增加作用加强.     

antagomiR-21上调SIRT1激活PI3K/Akt/eNOS信号通路改善T2DM大鼠冠状动脉内皮依赖性舒张

目的]探讨miR-21抑制剂antagomiR-21调控沉默信息调节因子1(SIRT1)对2型糖尿病(T2DM)大鼠冠状动脉内皮依赖性舒张的影响及其机制。 [方法]以腹腔注射链脲佐菌素加高脂饲料喂养的方法建立T2DM大鼠模型,将28只成模大鼠随机分为模型组、antagomiR-NC组、antagomiR-21组、antagomiR-21＋SIRT1抑制剂EX527组,每组7只；另将7只普通饲料喂养的正常大鼠作为对照组。观察大鼠冠状动脉血流变化,采用离体血管环灌流技术观察大鼠冠状动脉的舒张功能。将体外培养的人冠状动脉内皮细胞(HCAEC)分为甘露醇组、高糖组、高糖＋antagomiR-NC组、高糖＋antagomiR-21组、高糖＋antagomiR-21＋EX527组,采用qRT-PCR检测miR-21、SIRT1的mRNA表达,Western blot检测SIRT1、磷脂酰肌醇3-激酶(PI3K)、蛋白激酶B(Akt)、内皮型一氧化氮合酶(eNOS)及其磷酸化蛋白的表达。 [结果]与对照组相比,T2DM模型大鼠冠状动脉中miR-21水平升高96.88%,而SIRT1蛋白和mRNA水平、冠状动脉流量分别降低40.85%、64.29%、22.15%(P＜0.05)；与甘露醇组比较,体外高糖处理的HCAEC中miR-21表达升高285.71%,SIRT1蛋白和mRNA表达水平分别降低44.78%、74.51%(P＜0.05)；antagomiR-21干预后体内外miR-21水平分别降低77.42%、58.66%,SIRT1蛋白水平分别升高55.56%、91.43%,SIRT1 mRNA水平分别升高88.57%、97.30%(P＜0.05)；与模型组相比,antagomiR-21干预后大鼠冠状动脉流量升高19.23%,10－8 mol/L、10－7 mol/L、10－6 mol/L及10－5 mol/L乙酰胆碱(Ach)诱导的大鼠冠状动脉舒张率分别升高111.89%、41.88%、41.98%、30.01%(P＜0.05),10－8 mol/L、10－7 mol/L、10－6 mol/L及10－5 mol/L去氧肾上腺素(Phe)诱导的大鼠冠状动脉收缩率分别降低36.71%、47.90%、49.19%、45.27%(P＜0.05)；antagomiR-21干预后HCAEC中PI3K、Akt、eNOS的磷酸化水平较高糖组分别升高48.48%、81.40%、134.29%(P＜0.05)；EX527处理可明显逆转体内外antagomiR-21引起的上述变化(P＜0.05)。 [结论]antagomiR-21可通过上调SIRT1表达激活PI3K/Akt/eNOS信号通路,从而改善T2DM大鼠冠状动脉内皮依赖性舒张。     

消化系恶性肿瘤病人LAK细胞和NK细胞功能与表型的变化

通过观察20例正常人和24例消化系恶性肿瘤病人外周血自然杀伤细胞(NK)和淋巴因子激活的杀伤细胞(LAK)的活性变化,以及加用重组白细胞介素2(rIL-2)刺激前后T淋巴细胞表型变化。结果发现肿瘤病人的NK细胞活性明显下降,但经rIL-2激活后LAK细胞活性得到明显提高,其溶解率接近正常水平。肿瘤病人的总T淋巴细胞(CD_(3+))和辅助/诱导T淋巴细胞(CD_(4+))水平低于正常,但抑制/杀伤淋巴细胞(CD_(8+))水平正常。辅助/诱导淋巴细胞与抑制/杀伤淋巴细胞之比为1.18,低于正常水平(1.55)。经加入rIL-2培养后,CD_(3+)和CD_(8+)淋巴细胞的比率明显升高并达正常水平。而在正常人此变化不明显,且加用rIL-2培养与不加者无显著差异。IL-2受体的表达正常人与肿瘤病人无异。结果显示胃肠道恶性肿瘤病人的免疫机制受到抑制,但能被IL-2提高至正常水平。     

Robust measurement of telomere length in single cells

Measurement of telomere length currently requires a large population of cells, which masks telomere length heterogeneity in single cells, or requires FISH in metaphase arrested cells, posing technical challenges. A practical method for measuring telomere length in single cells has been lacking. We established a simple and robust approach for single-cell telomere length measurement (SCT-pqPCR). We first optimized a multiplex preamplification specific for telomeres and reference genes from individual cells, such that the amplicon provides a consistent ratio (T/R) of telomeres (T) to the reference genes (R) by quantitative PCR (qPCR). The average T/R ratio of multiple single cells corresponded closely to that of a given cell population measured by regular qPCR, and correlated with those of telomere restriction fragments (TRF) and quantitative FISH measurements. Furthermore, SCT-pqPCR detected the telomere length for quiescent cells that are inaccessible by quantitative FISH. The reliability of SCT-pqPCR also was confirmed using sister cells from two cell embryos. Telomere length heterogeneity was identified by SCT-pqPCR among cells of various human and mouse cell types. We found that the T/R values of human fibroblasts at later passages and from old donors were lower and more heterogeneous than those of early passages and from young donors, that cancer cell lines show heterogeneous telomere lengths, that human oocytes and polar bodies have nearly identical telomere lengths, and that the telomere lengths progressively increase from the zygote, two-cell to four-cell embryo. This method will facilitate understanding of telomere heterogeneity and its role in tumorigenesis, aging, and associated diseases.Telomeres are the ribonucleoprotein structures that cap and protect linear chromosome ends from genomic instability and tumorigenesis (1, 2). Intriguingly, telomere shortening protects against tumorigenesis by limiting cell growth (3, 4), but also can impair tissue regenerative capability and cell viability (5, 6).Thus far, most assays of telomere length measure average telomere length from aggregates of many cells derived from dissected tissues, cultured cells, or blood (7). Telomere restriction fragment (TRF) determination (1, 8), a Southern blot-based technique, remains the “gold standard” for determining absolute telomere length, but requires a large amount of starting material (0.5–5 µg DNA) and several days for processing. Moreover, the requirements for gel electrophoresis and hybridization limit the scalability of this assay. Recently, a quantitative PCR (qPCR)-based method for telomere length measurement was developed, providing the convenience and scalability of PCR (9). Although the DNA requirement (35 ng) for qPCR is significantly less than TRF, it still relies on populations of cells to derive sufficient amount of DNA.Quantitative FISH (Q-FISH) allows sensitive visualization of relative telomere length from individual cells and individual telomeres, but this method requires many cells or metaphase arrested cells, which precludes its application to many sample types, including postmitotic cells, senescent cells, and other nondividing cells, and when only one actual cell is required to test. In addition, preparing chromosome spreads requires significant technical skill, and only proliferating cells within a population reach metaphase stage, so this analysis potentially biases the estimates of telomere length for a given cell population (10–12). High-throughput Q-FISH, flow FISH, and single telomere length analysis can be used for telomere measurement of dividing, nondividing, and senescent cells, but these methods also require large cell populations (13–15).The ability to measure telomere length in single cells rather than relying upon average telomere length in cell populations or the entire tissue enables the study of biological heterogeneity on a cell-by-cell basis, an issue of fundamental importance for studies of aging, development, carcinogenesis, and many other diseases. Here, we demonstrate an accurate determination of telomere length in individual cells, with the resolution and scalability of the qPCR telomere length assay.The basis of qPCR is that within a given cell, the ratio of the copy number of telomere repeats to the copy number of a multicopy reference gene is fixed (3), and this method, because of its simplicity, has been widely used to investigate a variety of telomere shortening-associated diseases (7), even sensitive enough to identify mild telomere dysfunction resulting from chronological life stress (16, 17). We adapted qPCR to measure telomere length in individual cells by using a preamplification step that specifically targets both the telomere and multicopy genes, followed by a qPCR assay to obtain telomere to reference gene (T/R) ratio. A single-cell telomere (SCT) length measurement method (SCT-pqPCR) runs robustly, and shows an identical T/R ratio for two sister blastomeres from two-cell–stage mouse embryos. The average result from SCT-qPCR with multiple single cells is linearly correlated to Q-FISH, TRF, and conventional qPCR assays designed for a large number of cells. The heterogeneity of telomere length among several populations of cells by SCT-pqPCR run on multiple single cells is consistent with—and sometimes superior to—results obtained by Q-FISH. Application of SCT-pqPCR to study telomere length during early embryo development, aging, and cancer demonstrate the value of this single-cell telomere length assay method.     

Processivity of peptidoglycan synthesis provides a built-in mechanism for the robustness of straight-rod cell morphology

The propagation of cell shape across generations is remarkably robust in most bacteria. Even when deformations are acquired, growing cells progressively recover their original shape once the deforming factors are eliminated. For instance, straight-rod-shaped bacteria grow curved when confined to circular microchambers, but straighten in a growth-dependent fashion when released. Bacterial cell shape is maintained by the peptidoglycan (PG) cell wall, a giant macromolecule of glycan strands that are synthesized by processive enzymes and cross-linked by peptide chains. Changes in cell geometry require modifying the PG and therefore depend directly on the molecular-scale properties of PG structure and synthesis. Using a mathematical model we quantify the straightening of curved Caulobacter crescentus cells after disruption of the cell-curving crescentin structure. We observe that cells straighten at a rate that is about half (57%) the cell growth rate. Next we show that in the absence of other effects there exists a mathematical relationship between the rate of cell straightening and the processivity of PG synthesis—the number of subunits incorporated before termination of synthesis. From the measured rate of cell straightening this relationship predicts processivity values that are in good agreement with our estimates from published data. Finally, we consider the possible role of three other mechanisms in cell straightening. We conclude that regardless of the involvement of other factors, intrinsic properties of PG processivity provide a robust mechanism for cell straightening that is hardwired to the cell wall synthesis machinery.     

特应性皮炎的免疫学发病机制

特应性皮炎是慢性复发性炎症性皮肤疾病，发病机制复杂，其中变态反应因素在发病机制中扮演着重要角色。目前认为Th1／Th2平衡失调是特应性皮炎重要的发病机制。本文围绕这一机制综述T细胞、树突状细胞、角质形成细胞及IgE在特应性皮炎发病机制中的作用。     

Regenerative medicine for the treatment of heart disease

Heart failure is a major cause of mortality worldwide with a steady increase in prevalence. There is currently no available cure beyond orthotopic heart transplantation, which for a number of reasons is an option only for a small fraction of all patients. Considerable hope has therefore been placed on the possibility of treating a failing heart by replacing lost cardiomyocytes, either through transplantation of various types of stem cells or by boosting endogenous regenerative mechanisms in the heart. Here, we review the current status of stem and progenitor cell‐based therapies for heart disease. We discuss the pros and cons of different stem and progenitor cell types that can be considered for transplantation and describe recent advances in the understanding of how cardiomyocytes normally differentiate and how these cells can be generated from more immature cells ex vivo. Finally, we consider the possibility of activation of endogenous stem and progenitor cells to treat heart failure.     

白藜芦醇对人肾癌细胞增殖和细胞周期的影响

目的探讨白藜芦醇（Res）对人肾癌细胞786-0（以下简称肾癌细胞）增殖和周期的影响。方法分别采用12.5、25、50、100μmol/L的白藜芦醇（Res）作用于肾癌细胞24 h;并设空白对照组。流式细胞仪检测细胞细胞周期。结果各浓度Res对肾癌细胞增殖均具有明显的抑制作用,表现为G1期及G2期细胞比例明显降低,S期比例明显升高,与对照组比较,P均〈0.05。Res 12.5μmol/L与25、50及100μmol/L比较,P均〈0.05;但25μmol/L与50、100μmol/L比较,P〉0.05。12.5μmol/L的Res抑制作用明显,当浓度达到25μmol/L时,抑制作用达最强;而继续升高浓度不能提高抑制作用。结论 Res对人肾癌细胞增殖有抑制作用,且具有剂量依赖性。     

Propagation of large numbers of T cells with natural killer cell markers

Summary. Previously, a subset of T cells co-expressing the NK cell antigen CD56 has been described. These CD3⁺CD56⁺ cells are rare in peripheral blood collections and have been poorly characterized. We have developed culture conditions which allow for the rapid expansion of CD3⁺CD56⁺ cells. The protocol for cellular expansion includes the addition of interferon-gamma on day O, interleukin-1, interleukin-2 and a monoclonal antibody against CD3 on day 1 to peripheral blood lymphocytes. Cells of the CD3⁺CD56⁺ phenotype increased up to 6000-fold using this protocol after 16 d in culture. These cells have been characterized by flow cytometry and have been found to express the alpha, beta T cell receptor, co-express the CD5 and CD8 antigens and do not express the CD16 antigen. Morphologically, these cells cannot be distinguished from NK cells. CD3⁺CD56⁺ killer cells lyse a variety of tumour cells with intermediate activity between CD3^?CD56⁺ NK cells and CD3⁺CD56^? T cells.     

骨髓干细胞移植在心血管疾病中的应用

近年来的研究表明，骨髓干细胞向心肌细胞分化已成为可能，动物模型及临床应用均证实，将骨髓干细胞移植于受损心肌可改善心肌缺血及心脏功能。     

肺干细胞研究进展

干细胞研究是现代医学领域研究热点之一.肺部疾病所导致的不同程度呼吸系统病理改变和功能受损,都伴随着肺组织的修复和重塑过程.对于肺部疾病的干细胞研究和应用尚有许多问题有待进一步的明确和探索.肺干细胞包括了肺组织自身的干细胞修复和肺外组织来源的干细胞修复.肺组织内的干细胞包括肺内上皮性干细胞、肺问充质干细胞、肺侧群细胞;其中肺内上皮性干细胞又包括了基底细胞、Clara细胞、Ⅱ型肺泡上皮细胞、"芽孢"样细胞.肺外组织来源的干细胞修复包括骨髓间充质干细胞和造血干细胞.干细胞治疗方法在临床上有巨大的应用前景.