纳米SiO_2对poss复合树脂弯曲和抗压强度的影响

目的:观察纳米SiO2填料对纳米复合树脂poss的弯曲强度和抗压强度的影响,探究纳米SiO2的最佳添加比。方法:将经过硅烷偶联化的纳米SiO2颗粒加入poss复合树脂中,合成SiO2质量分数分别为0.5%,1%,1.5%和2%的SiO2/poss复合树脂,分别为BCDE四组,纯poss组为A组(对照组)。每组试件固定于万能材料测试机上,以1.0mm/min的速度垂直加压直至试样破坏,采用SPSS16.0软件对结果做单因素方差分析。结果:弯曲强度测试结果:C组最高,与其他四组均有统计学差异(P0.05);A、B、D三组无显著性差异,与E组差异明显(P0.05)。抗压强度测试结果:D组最高,与其他四组均有统计学差异(P0.05);B组和E组与A组差异显著(P0.05),与C组无显著差异。结论:纳米SiO2在一定范围内能够提高poss复合树脂的弯曲强度和抗压强度。     

MiRNA在TLR信号通路中的负性调控作用

TLR信号是生物体重要的病原体模式识别信号,在免疫识别和炎症反应中具有重要作用,其信号异常会导致许多免疫和炎症相关疾病的发生,因此探讨和明确TLR信号通路的调控机制具有非常重要的意义。近年来研究发现,作为重要的基因表达调控的小分子RNA,微RNA(microRNA,miRNA)能与TLR信号通路中众多靶基因mRNA的3’UTR区结合,从而抑制翻译过程或降解mRNA来发挥负性调控作用。本文就miRNA对TLR信号通路中的一些受体、信号分子、调节因子和细胞因子的负性调控作用方面进行阐述。     

黄热病病毒检测微阵列的研究制备

目的:制备黄热病病毒寡核苷酸检测微阵列.方法:根据黄热病病毒基因组序列,并应用生物信息学软件设计出寡核苷酸探针用于制备基因芯片,克隆于质粒上的黄热病病毒全长基因DNA经限制性显示技术扩增并标记,完成杂交后对芯片进行扫描和数据分析.结论:微阵列检测技术为检测黄热病病毒提供了一种早期、快速、可靠的方法,具有应用于临床检测的前景.     

Differential use of two AP-3-mediated pathways by lysosomal membrane proteins

The adaptor protein complex AP-3 is involved in the sorting of lysosomal membrane proteins to late endosomes/lysosomes. It is unclear whether AP-3-containing vesicles form at the trans-Golgi network (TGN) or early endosomes. We have compared the trafficking routes of endolyn/CD164 and 'typical' lysosomal membrane glycoproteins (lgp120/lamp-1 and CD63/lamp-3) containing cytosolic YXXPhi-targeting motifs preceded by asparagine and glycine, respectively. Endolyn, which has a NYHTL-motif, is concentrated in lysosomes, but also occurs in endosomes and at the cell surface. We observed predominant interaction of the NYHTL-motif with the mu-subunits of AP-3 in the yeast two-hybrid system. Endolyn was mislocalized to the cell surface in AP-3-deficient pearl cells, confirming a major role of AP-3 in endolyn traffic. However, lysosomal delivery of endolyn (or a NYHTL-reporter), but not GYXXPhi-containing proteins, was practically abolished when AP-2-mediated endocytosis or traffic from early to late endosomes was inhibited in NRK and 3T3 cells. This indicates that endolyn is mostly transported along the indirect lysosomal pathway (via the cell surface), rather than directly from the TGN to late endosomes/lysosomes. Our results suggest that AP-3 mediates lysosomal sorting of some membrane proteins in early endosomes in addition to sorting of proteins with intrinsically strong AP-3-interacting lysosomal targeting motifs at the TGN.     

Effects of melatonin on carbonic anhydrase from human erythrocytes in vitro and from rat erythrocytes in vivo

The in vitro effects of melatonin (N-acetyl-5-methoxy-tryptamine) on human carbonic anhydrase isozymes (HCA-I and HCA-II) from human erythrocytes and in vivo effects on rat erythrocytes carbonic anhydrase (CA) were determined. Human erythrocyte carbonic anhydrase isozymes were purified by haemolysate preparation and Sepharose-4B-L tyrosine-sulfanilamide affinity gel chromatography. The HCA-I enzyme, having a specific activity of 7337.5 EU/mg protein, was purified 843-fold with a yield of 60% and the HCA-II enzyme, having a specific activity of 17067EU/mg protein, was purified 1962-fold with a yield of 22.7%. For in vitro experiments, the enzyme activity was minimal at 2 x 10(-4) M melatonin concentration and increased above this concentration. Ten mgkg(-1) melatonin was administered intraperitoneally and showed a stimulatory effect on the enzyme. Time-dependent in vivo studies were conducted for melatonin in Sprague-Dawley type rats. It was found that CA activity in the rat erythrocytes was decreased by the melatonin after 1 and 3 hours to 2500 +/- 500.0 and 1875 +/- 239.4 respectively which were statistically significant (p < 0.05) differences to the control (2660 +/- 235.8). However, CA activity was restored to its normal level after 6h (2666 +/- 235.7) (p > 0.05) probably due to metabolism of the melatonin. The findings indicate that melatonin may be pharmacologically useful in some diseases.     

The detection of shared and ancestral polymorphisms

There is increasing evidence that closely related species contain many polymorphisms that were present in their common ancestral species. Use of a more distant relative as an outgroup increases the ability to detect such ancestral polymorphisms. We describe a method for further improving estimates of the fraction of polymorphisms that are ancestral, and illustrate this with reference to data on Drosophila pseudoobscura and D. miranda. We also derive formulae for the proportion of fixations arising from ancestral polymorphisms and new mutations, respectively. The results should be useful for tests of selection based on the levels of expected and observed ancestral polymorphisms.     

肿瘤抑制因子Hamartin和Tuberin信号调控机制

结节硬化复合症由tscl、tsc2基因突变引起,这2个基因分别编码hamartin和tuberin,它们均为肿瘤抑制因子,在细胞生长和增殖过程中起关键性的调节作用。生长因子刺激的PI3K／Akt信号通路通过磷酸化tuberin,调控下游效应因子功能,最终影响细胞的生长和增殖。现对hamartin和tuberin信号调控机制的最新进展进行综述,并展望其发展趋势。     

TREM2在阿尔茨海默病发病进程中双重作用的研究进展

阿尔茨海默病(AD)是一种进行性发展的神经退行性疾病,目前尚无确切有效治疗措施。近年来研究发现基因编码的髓样细胞触发受体2(TREM2)可通过加强吞噬β-淀粉样蛋白(Aβ)及抑制中枢神经炎症而改善AD症状,并且TREM2功能缺失或缺陷的变体会加剧Aβ毒性进而增加AD风险。因此,近年来TREM2基因成为AD有效预防和治疗的靶点的研究热点之一。然而,近期的一些研究表明TREM2是一把双刃剑:在AD早期阶段,TREM2缺陷可防止大脑受Aβ的侵害;但是在AD晚期,TREM2功能缺失会加重大脑毒性损伤。本文就从TREM2与AD发病机制的关系的最新进展予以综述。     

基于信息随访平台的延续护理在宫颈癌PICC带管出院患者中的应用

目的探讨PICC带管出院患者延续护理的方法,保证患者带管出院期间安全。方法应用信息随访平台,对238例宫颈癌患者留置PICC导管带管出院期间实施延续护理。结果通过信息随访平台对带管出院患者实施延续护理后,患者在离院期间未发生脱管、断管、化学性静脉炎、血栓性静脉炎等现象,无患者因为维护不便而非计划拔管。结论通过信息随访平台为PICC带管出院患者提供延续护理,简化了护士工作,给患者安心体验,利于PICC导管管理,减少并发症。