RNAi and heterochromatin repress centromeric meiotic recombination

During meiosis, the formation of viable haploid gametes from diploid precursors requires that each homologous chromosome pair be properly segregated to produce an exact haploid set of chromosomes. Genetic recombination, which provides a physical connection between homologous chromosomes, is essential in most species for proper homologue segregation. Nevertheless, recombination is repressed specifically in and around the centromeres of chromosomes, apparently because rare centromeric (or pericentromeric) recombination events, when they do occur, can disrupt proper segregation and lead to genetic disabilities, including birth defects. The basis by which centromeric meiotic recombination is repressed has been largely unknown. We report here that, in fission yeast, RNAi functions and Clr4-Rik1 (histone H3 lysine 9 methyltransferase) are required for repression of centromeric recombination. Surprisingly, one mutant derepressed for recombination in the heterochromatic mating-type region during meiosis and several mutants derepressed for centromeric gene expression during mitotic growth are not derepressed for centromeric recombination during meiosis. These results reveal a complex relation between types of repression by heterochromatin. Our results also reveal a previously undemonstrated role for RNAi and heterochromatin in the repression of meiotic centromeric recombination and, potentially, in the prevention of birth defects by maintenance of proper chromosome segregation during meiosis.     

Control of Mechanical Properties of Thermoplastic Polyurethane Elastomers by Restriction of Crystallization of Soft Segment

Mechanical properties of thermoplastic polyurethane elastomers based on either polyether or polycarbonate (PC)-glycols, 4,4’-dipheylmethane diisocyanate (1,1’-methylenebis(4-isocyanatobenzene)), 1,4-butanediol, were controlled by restriction of crystallization of polymer glycols. For the polyether glycol based-polyurethane elastomers (PUEs), poly(oxytetramethylene) glycol (PTMG), and PTMG incorporating dimethyl groups (PTG-X) and methyl side groups (PTG-L) were employed as a polymer glycol. For the PC-glycol, the randomly copolymerized PC-glycols with hexamethylene (C₆) and tetramethylene (C₄) units between carbonate groups with various composition ratios (C₄/C₆ = 0/100, 50/50, 70/30 and 90/10) were employed. The degree of microphase separation and mechanical properties of both the PUEs were investigated using differential scanning calorimetry, dynamic viscoelastic property measurements and tensile testing. Mechanical properties could be controlled by changing the molar ratio of two different monomer components.     

雷达式非接触检测中呼吸和心跳信号分离算法的研究

为了有效地从生物雷达的体动信号中分离出呼吸和心跳信号,实现生理特征参数（呼吸率和心率）实时监测,本文在自适应噪声抵消模型的基础上,提取呼吸信号的谐波组合作为模型的参考输入,将生物雷达检测到的体动信号作为模型的原始输入,构建了一套适用于生物雷达检测中分离呼吸、心跳信号的自适应谐波抵消算法。仿真实验结果表明,该算法简单、易于实现,能够实时地分离呼吸和心跳信号。     

关于制药分离工程精品课程建设的探索与实践

总结了制药分离工程课程被评为郑州大学精品课程后,所做的教学实践与教学改革工作,通过总结课程建设的经验,反映制药分离工程精品课程建设的特色。     

金黄色葡萄球菌临床监测与葡萄球菌A蛋白快速检验研究

目的分析临床金黄色葡萄球菌(SA)分布特征及耐药性,并建立可用于检测葡萄糖球菌A蛋白(SPA)的新方法。方法分析132株SA菌株的分布特征与耐药性。构建金属螯合免疫磁性微球,对其表面形态、大小、表面基团吸收峰进行测定,用该磁性微球分离SPA,并用于SA检测。结果 132株SA分离自痰液74株(占56.06%)、分泌物43株(占32.58%)、血液10株(占7.57%)、胆汁3株(占2.23%)、器械导管2株(占1.52%)。检出甲氧西林敏感SA(MSSA)61株(占46.21%),对青霉素G、左氧氟沙星、庆大霉素、克林霉素、红霉素的耐药率分别为93.12%、13.23%、23.12%、56.87%、54.23%;甲氧西林耐药SA(MRSA)71株(占53.79%),对青霉素G、复方磺胺甲噁唑、左氧氟沙星、庆大霉素、克林霉素的耐药率分别为92.12%、21.21%、61.21%、29.21%、76.23%。磁性微球分散性良好,对SA样品的检测灵敏度可达100CFU,在一定条件下可维持高活性3周。结论 SA菌株耐药性较强;免疫磁性微球技术可用于SA的快速检测,值得推广应用。     

膜分离与沉淀剂结合提取腌肠衣盐水中肝素纳的工艺研究

目的探讨膜分离与沉淀剂结合提取腌肠衣盐水中肝素纳的工艺改进。方法采用盐解-离子交换-膜分离及蛋白沉淀除杂法从中提取肝素纳。结果从废弃的腌肠衣盐水中提取肝素钠取得了成功,与传统工艺（盐解-离子交换法）比较,洗脱液体积可浓缩至原体积的15％左右,乙醇用量可减少85％左右,而效价分别从传统工艺的96．82U／mg增加到157．58U／mg,总收率比传统工艺提高了12．5％。结论工艺方法可行、可靠,适宜于中、小型规模的生产。     

Catastrophic failure of a modular revision total hip polyethylene insert

Early catastrophic failure of a modular polyethylene component is a potential problem after revision total hip arthroplasty. We describe an unusual case of polyethylene failure that occurred within 18 months of implantation in which no obvious technical error or mechanical failure was identified. The acetabular polyethylene insert was prepared with gas plasma sterilization, and the shelf life was 4 months. Radiographic evaluation used generalized Hough transforms to assess the cup articulation. We identified cup penetration of 2.8 mm before revision and catastrophic destruction of the polyethylene liner at the time of revision. Possible factors implicated for failure included a thin polyethylene liner, increased hip separation, femoral head mismatch, and the high activity level of a younger patient. We believe that this case report highlights the need for future investigations of these subtle factors.     

Late fiber metal shedding of the first and second-generation Harris Galante acetabular component. A report of 5 cases

Five patients presented with fiber metal mesh shedding of a Harris Galante II acetabular cup detected between 11 and 15 years after implantation. All patients presented with hip pain and 4 demonstrated gross acetabular loosening and fiber metal separation on preoperative radiographs. The remaining patient underwent revision surgery because of a liner dislodgment and had a radiographically well fixed shell. Loosening and fiber metal separation were detected intraoperatively. Scanning electron microscopy of the retrieved shells demonstrated isolated diffusion bonding marks in the areas where the mesh separated from the substrate and no evidence of corrosion. Progressive osteolysis in the iliac bone was evident in 4 of our cases. Progressive iliac osteolysis may lead to loss of bone support in well-fixed cups and excessive stresses transferred to the interface between the fiber metal mesh and the titanium substrate leading to the separation of the 2 layers. Fiber metal separation may contribute to long-term loosening in the Harris Galante acetabular component.     

药房托管的现状、问题及对策

药房托管作为一种医药分开的过渡模式,顺应专业化管理的社会分工趋势,有利于减轻患者的疾病经济负担。但是,药房托管模式在运行中存在“内部人控制”,受托企业利润低、人事管理困难,在三级医院推广困难等问题。本文对此进行了分析,并提出了对策。     

肝卵圆细胞及其定向诱导分化为胰岛细胞的相关研究

胰岛细胞移植是治愈糖尿病的可能方法 ,但胰岛细胞数量有限,不能满足临床需要. 肝卵圆细胞可以在体外诱导分化为胰岛细胞,因此可以作为胰岛细胞潜在的替代资源.文章就肝卵圆细胞及其定向诱导分化为胰岛细胞的相关研究作一综述.