Synthesis and biological evaluation of pyrimidine derivatives as novel human Pin1 inhibitors

Pin1 (Protein interacting with NIMA1) is a cis–trans isomerase and promotes the amide bond rotation of phosphoSer/Thr-Pro motifs in its substrates. Inhibition of Pin1 might be a novel strategy for developing anticancer agents. Herein, a series of pyrimidine derivatives were synthesized and their Pin1 inhibitory activities were evaluated. Among them, four compounds (2a, 2f, 2h and 2l) displayed potent inhibitory activities against Pin1 with IC₅₀ values lower than 3?µM. This series of pyrimidine-based inhibitors presented time-dependent inhibition against Pin1. The structure–activity relationships on the 2-, 4- and 5-positions of the pyrimidine ring were analyzed in details, which would facilitate further exploration of new Pin1 inhibitors.     

Use of chemically modified PMMA microspheres for enzyme immobilization

Modified poly(methyl methacrylate) (PMMA) microspheres, about 7microm in diameter, carrying aldehyde groups on their surfaces were synthesized and used as the support for enzyme immobilization. The immobilizing behavior as well as the properties of immobilized enzyme was studied. The amount of bound enzyme can be extended to 76.8mg g(-1) support, which is relatively much higher than other supports. The kinetic investigation derived from three typical models shows that the practical process is more complicated than the ideal condition, with one or more interactions being involved in the immobilization process. The K(m) value is actually larger and V(max) is smaller in the immobilized form than those in the free form. The increased resistance of the immobilized enzyme against the changes of temperature indicates that immobilizing enzyme onto the modified microspheres is useful for enzyme immobilization.     

Properties of immobilized pepsin on Modified PMMA microspheres

In this work we use micro-size poly(methyl methacrylate)/acrylaldehyde microspheres as a support for pepsin immobilization. The aldehyde groups on the microspheres offer a very simple, mild and firm combination for enzyme immobilization. The amount of enzyme we can bind to this support reaches 82 mg/g, which is much higher than for other supports (mostly less than 10 mg/g). Compared to free enzyme, the Km of immobilized enzyme is increased, whereas the Vmax is decreased. Further, the Vmax/Km value for immobilized pepsin is about 50% of the value for free enzyme. This is better than values reported previously, generally lower than 35%. The optimum temperature shifts from 43 degrees C for free pepsin to 47 degrees C. However, the optimum pH does not change between free and immobilized enzyme. This improved resistance of the immobilized enzyme towards changes in temperature and pH also shows that the aldehyde modified poly(methyl methacrylate)/acrylaldehyde microspheres can be a valuable support for pepsin immobilization.     

基于GIS的沿海地区生态安全时空测度与演变——以大连市瓦房店为例

以大连瓦房店市2000年、2005年和2010年Landsat TM遥感影像(轨道号为120/32,120/33)作为数据源,在景观格局分析的基础上,基于压力-状态-响应(P-S-R)框架构建沿海地区生态安全评价体系,在GIS格网技术下量化多源数据,创建区域生态安全格网数据库,采用加权-模糊隶属度评价方法进行生态安全状态评价,并通过空间统计学方法对研究区生态安全格局时空演变进行分析,揭示沿海地区生态安全时空演变特点。结果表明:12000—2010年瓦房店市生态安全指数平均值分别为0.4636、0.3878和0.3980,说明研究区生态安全恶化后又有缓升趋势,但西部沿海地区生态安全依然需要重视。2Moran's I从2000年到2010年分别为0.9015、0.8738和0.8703,表明瓦房店市生态安全指数在空间上存在较强的正相关关系,生态安全格局表现为高值区域倾向于与生态安全程度高的区域相毗邻,而生态安全程度低的区域倾向于与生态安全程度低的区域毗邻,2000—2005年表现极为明显。32000—2010年瓦房店市生态安全指数的块金值分别为0.0030、0.0007和0.0009,表明非结构因素对研究区生态安全空间分布影响效应逐渐增强,这与10年来瓦房店城市建设用地扩张、人类活动频繁的实际情况相符。CO/(CO+C)值也是先增加后减少,表明非结构因素对研究区生态安全空间分异的影响效应先增强后减弱,2005年以来随着大连市土地政策的实施与管理,城镇建设、人类活动等非结构因素对生态安全演变影响有所消减。     

Synthesis and biological evaluation of novel quinazoline-derived human Pin1 inhibitors

A series of novel 2,4-disubstituted quinazoline derivatives were prepared and their inhibitory activities on hPin1 were evaluated. Of all the synthesized compounds, eight compounds displayed inhibitory activities with IC(50) value at the level of 10(-6)mol/L. Preliminary structure-activity relationships were analyzed in details and the binding mode of the titled compounds was predicted using FlexX algorithm. The design and optimization of novel small molecule Pin1 inhibitors will be guided by the results of this report.     

内蒙古草甸草原与典型草原地下生物量与生产力季节动态及其碳库潜力

地下根系是草原生态系统的重要组成部分,其生物量及其净生产力对地下碳库具有直接与间接作用,分析地下生物量季节动态与周转对深入揭示草原生态系统碳库动态及其固碳速率与潜力具有重要意义。应用钻土芯法对不同利用方式或管理措施下内蒙古草甸草原、典型草原地下生物量动态及其与温度、降水的相关性研究表明:草甸草原和典型草原地上生物量季节动态均为单峰型曲线,与上月降水显著正相关(P0.05),但地下生物量季节动态表现为草甸草原呈"S"型曲线,典型草原则是双峰型曲线,与温度、降水相关性均不显著(P0.05);两种草原根冠比和地下生物量垂直分布均为指数函数曲线,根茎型草原地下生物量集中在土壤0—5 cm,丛生型草原地下生物量集中于土壤5—10 cm,根冠比值在生长旺季(7—8月份)最小。草甸草原地下净生产力及碳储量范围分别为2167—2953 g m-2a-1和975—1329 gC m-2a-1,典型草原为2342—3333 g m-2a-1和1054—1450 gC m-2a-1,地下净生产力及其碳储量约为地上净生产力及其碳储量的10倍,具有较大的年固碳能力,且相对稳定;地下净生产力与地上净生产力呈显著负相关性(P0.05);地下生物量碳库是地上生物量碳库的10倍左右,适度放牧可增加地下生产力,但长期过度放牧显著降低其地下生物量与生产力,并使其垂直分布趋向于浅层化。     

JNK and STAT3 signaling pathways converge on Akt-mediated phosphorylation of EZH2 in bronchial epithelial cells induced by arsenic

The molecular mechanisms by which arsenic (As³⁺) causes human cancers remain to be fully elucidated. Enhancer of zeste homolog 2 (EZH2) is the catalytic subunit of polycomb-repressive complexes 2 (PRC2) that promotes trimethylation of lysine 27 of histone H3, leading to altered expression of tumor suppressors or oncogenes. In the present study, we determined the effect of As³⁺ on EZH2 phosphorylation and the signaling pathways important for As³⁺-induced EZH2 phosphorylation in human bronchial epithelial cell line BEAS-2B. The involvement of kinases in As³⁺-induced EZH2 phosphorylation was validated by siRNA-based gene silencing. The data showed that As³⁺ can induce phosphorylation of EZH2 at serine 21 in human bronchial epithelial cells and that the phosphorylation of EZH2 requires an As³⁺-activated signaling cascade from JNK and STAT3 to Akt. Transfection of the cells with siRNA specific for JNK1 revealed that JNK silencing reduced serine727 phosphorylation of STAT3, Akt activation and EZH2 phosphorylation, suggesting that JNK is the upstream kinase involved in As³⁺-induced EZH2 phosphorylation. Because As³⁺ is capable of inducing miRNA-21 (miR-21), a STAT3-regulated miRNA that represses protein translation of PTEN or Spry2, we also tested the role of STAT3 and miR-21 in As³⁺-induced EZH2 phosphorylation. Ectopic overexpression of miR-21 promoted Akt activation and phosphorylation of EZH2, whereas inhibiting miR-21 by transfecting the cells with anti-miR-21 inhibited Akt activation and EZH2 phosphorylation. Taken together, these results demonstrate a contribution of the JNK, STAT3 and Akt signaling axis to As³⁺-induced EZH2 phosphorylation. Importantly, these findings may reveal new molecular mechanisms underlying As³⁺-induced carcinogenesis.     

Synthesis and biological evaluation of novel human Pin1 inhibitors with benzophenone skeleton

A series of novel benzophenone derivatives were prepared and their inhibitory activities were evaluated on hPin1. Of all the synthesized compounds, the most active compound displayed inhibitory activities with an IC(50) value of 5.99 μmol/L. Preliminary structure-activity relationships were analyzed in details and the binding mode of the titled compounds was predicted using FlexX algorithm. The results of this research will shed light on further design and optimization of novel small molecule Pin1 inhibitors.     

Covalent immobilization of glucose oxidase onto poly(styrene-co-glycidyl methacrylate) monodisperse fluorescent microspheres synthesized by dispersion polymerization

In this study, micron-sized poly(styrene-co-glycidyl methacrylate) (PSt-GMA) fluorescent microspheres of 5.1microm in diameter were synthesized via dispersion polymerization of styrene and glycidyl methacrylate in the presence of 1,4-bis(5-phenyloxazol-2-yl) benzene (POPOP), which provided surface functional groups for covalent immobilization of enzymes. In an effort to study the biocompatibility of the microspheres' surface, glucose oxidase and beta-d-(+)-glucose were selected as a catalytic system for enzymatic assays. A colorimetric method was adopted in evaluating enzymatic activity by introducing horseradish peroxidase (HRP). Both the immobilization amount and the apparent activity of immobilized glucose oxidase from Aspergillus niger (GOD) were determined at different conditions. The results show that the immobilized enzymes retained approximately 28 to 34% activity, as compared with free enzymes, without pronounced alteration of the optimum pH and temperature. Kinetics studies show that the corresponding values of K(m) and V(max) are 23.2944 mM and 21.6450M/min.mg GOD for free enzymes and 35.1780 mM and 15.4799M/min.mg GOD for immobilized enzymes. The operational stability studies show that immobilized GOD could retain nearly 50% initial activity after being washed 20 times. The results suggest that the resultant PSt-GMA fluorescent microspheres provide a suitable surface for covalent immobilizing biomolecules; therefore, they have the potential of being used in fluorescence-based immunoassays in high-throughput screening or biosensors.     

慢病毒载体介导Bdnf基因修饰的骨髓间质干细胞移植治疗脑梗死

为研究经Bdnf基因修饰的骨髓间质干细胞(Mesenchymal stem cells, MSCs)对脑梗死的协同治疗作用, 构建带有大鼠Bdnf基因之慢病毒载体, 并感染大鼠骨髓间质干细胞(Rat mesenchymal stem cells, rMSCs)。运用线栓法制备大鼠大脑中动脉栓塞模型, 经尾静脉注射移植, 对照组注射0.1 mol/L磷酸盐缓冲液(PBS)1 mL, Bdnf-rMSCs和Mock-rMSCs组分别注射Bdnf-rMSCs细胞悬液以及未插入目的基因的空病毒载体感染后的rMSCs细胞悬液各1 mL。各组大鼠分别于术后24 h、移植后2周及2月应用modified Neurological Severity Scores (mNSS)评价神经功能状况。结果显示, 与对照组相比, Mock-rMSCs及Bdnf-rMSCs移植组神经功能改善明显, mNSS评分差异有统计学意义(P<0.001), 而且Bdnf-rMSCs移植组明显优于Mock-rMSCs移植组(P<0.001)。移植后2周及2月, 与对照组相比两移植组梗死区脑组织结构恢复较好, 均可见EGFP阳性细胞在梗死区及其周边区聚集并存活, 并有部分细胞出现神经元样改变。Bdnf- rMSCs移植组中移植细胞大量表达BDNF, 两移植组中均有部分植入细胞表达神经细胞表面标志物。研究表明Bdnf基因修饰的rMSCs经静脉移植后可迁移至脑梗死灶周围, 向神经细胞分化并长期存活。移植后的干细胞可与其分泌的BDNF协同促进脑梗死后神经功能恢复, 这为将来基因工程干细胞移植治疗脑梗死提供了实验依据。