Cytosolic and nuclear distribution of PPARgamma2 in differentiating 3T3-L1 preadipocytes

In light of the pivotal role that PPARgamma2 plays in the expression of fat specific genes (e.g., A-FABP), we have examined the hypothesis that a rise in PPARgamma2 protein is required for the expression of A-FABP, and that the acceleration of fat cell differentiation by the thiazolidinedione agent, pioglitazone (PIOG), reflects an increase in the abundance of PPARgamma2 mRNA and protein. Western analyses surprisingly revealed that undifferentiated 3T3-L1 fibroblasts contained significant levels of PPARgamma2 protein; that the amount of total cellular PPARgamma2 only increased 2-fold during differentiation; and that the levels of PPARgamma2 protein and mRNA were not increased by PIOG even though fat cell differentiation was accelerated by PIOG as revealed by a 20-fold increase in A-FABP expression. Cell fractionation studies revealed that PPARgamma2 was evenly distributed between the cytosolic and nuclear compartments in both undifferentiated and differentiating 3T3-L1 cells. Immunocytochemical studies with a PPARgamma2-specific antibody indicated that PPARgamma2 was diffusely distributed throughout the cytosol of undifferentiated 3T3-L1 cells, but as the differentiation progressed, the PPARgamma2 became focused around the developing lipid droplets. In contrast to PPARgamma2, undifferentiated 3T3-L1 cells contained no measurable quantities of RXRalpha, but once fat cell differentiation was initiated by treatment with IBMX and dexamethasone, the cellular content of RXRalpha increased several fold. The rise in RXRalpha content paralleled the induction of A-FABP, but the expression of RXRalpha was not enhanced by PIOG. Although the amount of PPARgamma2 and RXRalpha was unaffected by PIOG, gel shift assays revealed that PIOG stimulated PPARgamma2/RXRalpha binding to the adipose response element of A-FABP by 5-fold in less than 12 h. Apparently, RXRalpha rather than PPARgamma2 is the pivotal trans-factor essential for the initiation of terminal fat cell differentiation. However, the high cytsolic content of PPARgamma2 and its association with the lipid droplet of differentiating 3T3-L1 cells suggests PPARgamma2 may possess a cytosolic function in the developing fat cell.     

微波辐射对细胞膜通透性的影响

本实验通过电镜镧细胞化学方法，观察了微波辐射对生物样品细胞膜通透性的影响。在常规化学固定的情况下，镧颗粒沿细胞间隙密集分布而不能进入细胞内。生物样品经微波辐射后，在细胞内甚至在线粒体等细胞器内可观察到较多的镧颗粒。提示：微波辐射使生物膜的通透性发生了改变。     

桥梁基桩在含沙水流冲击作用下的冲蚀磨损数值模拟研究

过水桥梁的基桩外露已成为影响桥梁安全性的重要因素,携沙水流会对外露部分的基桩产生冲蚀作用,加速混凝土的破坏,累积到一定程度,会导致桥梁安全性降低,影响桥梁交通的正常运营。为研究携沙水流对基桩的冲蚀磨损规律及其影响因素,利用ANSYS-Workbench建立三维模型,在FLUENT的工作环境下,模拟水沙两相流的流动特性,并求解得出基桩最大冲蚀磨损速率。通过数值模拟,研究了携沙水流的流场特性,并得出了在不同流速、含沙量及粒径下的冲蚀磨损规律。结果表明:流速、含沙量及粒径都对最大冲蚀率有较大影响,其中,最大冲蚀率随流速的增加而增大,并呈现出明显的指数关系;含沙量与最大冲蚀率呈现出正相关关系;最大冲蚀率随粒径的增大呈现出先减少后趋于稳定的趋势。研究成果可以为后续基桩冲蚀磨损预测的工程应用提供相关依据。     

不同浊度下的泥沙对水体镉、铅、砷去除的影响分析

针对流域突发性重金属污染,不同浊度下的泥沙对重金属有一定的去除效果。以浊度为指示指标,通过试验研究了常温(25 ℃)和低温(5 ℃)条件下浊度50～650 NTU(Nephelometric Turbidity Unit)范围内泥沙对重金属镉、铅、砷吸附去除的影响。试验结果表明:泥沙对重金属镉、铅、砷的去除效果为铅＞镉＞砷,其中铅的去除率达到99%。浊度与能处理达标的最高重金属浓度呈线性关系,常温下浊度与能处理达标的最高镉、铅、砷浓度关系曲线的相关系数分别为0.996、0.998、0.999,低温下其相关系数分别为0.999、0.996、0.998。常温较低温更利于泥沙对重金属镉、铅、砷的去除,能去除更高浓度的重金属,达到生活饮用水卫生标准。     

Oxidative dimerisation of propene to 1,5-hexadiene on Bi-Zn-O catalysts

The oxidative dimerisation of propene to 1,5-hexadiene has been investigated on Bi-Zn-O catalysts. The Bi₄₈ZnO₇₃ phase, observed in the catalysts calcined at 700 ° C is an active and selective catalyst for the formation of 1,5-hexadiene. The best catalytic performance (1,5-hexadiene selectivity 64%) has been obtained at 525 ° C, with a propene to oxygen ratio of 26, on a catalyst formed by Bi₄₈ZnO₇₃ with a small excess of ZnO.     

用质子激发X射线分析方法进行人发微量元素的分析研究

一、序言 质子激发X射线分析方法是瑞典人约翰逊在1970年首先提出来的。由于它具有灵敏度高、取样少、无损伤、快速、适用范围广等特点,使它在十余年中在生物医学、环境科学、地质、冶金、考古学和法学等领域得到了广泛的应用。我们应用质子激发X射线分析方法分析了人发中的微量元素。     

用仪器中子活化分析法检验环境土壤标样的均匀度

近年来,国际上标准参考物质的种类与数量急剧增加,一些重要的领域,象地球化学、环境科学、生物学等都有了相应的SRM。国内研制SRM的工作也十分活跃。 标准样品必须均匀,故在分析定值和样品发行前,需要先作均匀性检验。由于均匀性是一个相对的概念,它与各个元素在SRM中的分布紧密相关。取样量直接影响均匀性的好坏。因此,当给出SRM中某元素的均匀性数值时,必须注明相应的取样量。由于仪器中子活化分析法(INAA)具有灵敏度高、不破坏试样、且可同时测定多种元素等特点,因此可在较小的取样量情况下,实现对SRM中多种痕量元素的均匀性检验。     

The Importance of Therapeutically Targeting the Binary Toxin from Clostridioides difficile

Novel therapeutics are needed to treat pathologies associated with the Clostridioides difficile binary toxin (CDT), particularly when C. difficile infection (CDI) occurs in the elderly or in hospitalized patients having illnesses, in addition to CDI, such as cancer. While therapies are available to block toxicities associated with the large clostridial toxins (TcdA and TcdB) in this nosocomial disease, nothing is available yet to treat toxicities arising from strains of CDI having the binary toxin. Like other binary toxins, the active CDTa catalytic subunit of CDT is delivered into host cells together with an oligomeric assembly of CDTb subunits via host cell receptor-mediated endocytosis. Once CDT arrives in the host cell’s cytoplasm, CDTa catalyzes the ADP-ribosylation of G-actin leading to degradation of the cytoskeleton and rapid cell death. Although a detailed molecular mechanism for CDT entry and host cell toxicity is not yet fully established, structural and functional resemblances to other binary toxins are described. Additionally, unique conformational assemblies of individual CDT components are highlighted herein to refine our mechanistic understanding of this deadly toxin as is needed to develop effective new therapeutic strategies for treating some of the most hypervirulent and lethal strains of CDT-containing strains of CDI.     

云南省白族和哈尼族婴幼儿膳食营养状况及生长发育的调查分析与评价

对云南省剑川县、墨江县的600名6 ～ 24个月龄婴幼儿进行膳食及健康调查,评价两地婴幼儿的生长发育情况,为当地卫生机构普及营养知识和少数民族营养支持计划提供数据支持.采用外科体检和膳食营养调查同步进行的方法对剑川白族和墨江县哈尼族6～24月龄婴幼儿膳食摄入状况及身体发育指标进行调查,并与参考文献中的其他地区同龄进行纵向比较,综合评价两地婴幼儿的健康发育状况.两地6～24月龄婴幼儿的营养摄入低于国家推荐量,并且生长发育指标低于城区的婴幼儿,剑川白族婴幼儿发育指标好于墨江哈尼族婴幼儿发育指标.剑川、墨江等地区的婴幼儿营养及身体发育指标偏低,婴幼儿营养摄入和发育状况均堪忧,有必要加强科学指导和管理,并进行营养包支持.     

基于改进FCM聚类的窃电行为检测

窃电行为检测的主要目的 在于发现窃电用户,降低电力系统运营成本.在此背景下,提出基于改进模糊C均值聚类的窃电行为检测模型,包括因子分析、基于改进模糊C均值聚类的局部离群因子计算、ROC曲线模型评价与调参及最佳检测阈值选取等模块,适用于无大量已知窃电用户样本的情况.首先,通过因子分析对用户用电特征(包括用电负荷数据和电能表异常事件)进行维度规约,提升模型检测效率.再利用遗传模拟退火算法对模糊C均值聚类算法进行改进,对用户用电特征进行检测.最后与现有成熟算法进行比较,验证该模型对窃电行为具有较高的检测准确度.检测模型可输出所有被测用户用电行为离群度得分和窃电概率排序,利用该文检测模型的输出,能够以较高精度检测出窃电行为用户,根据结果进行现场稽查,可提升反窃电工作效率.