A novel direction of arrival estimator

A Direction Of Arrival(DOA) estimator based on the signal separation principle is introduced, and one of representative multidimensional estimators is established by introducing Matrix Operator projection signal steering Vector Excision(MOVE) operation. Thanks to Alternating Separation (AS) technique, the multidimensional problem is transformed into a series of one-dimensional optimal ones. Furthermore, an equivalent simplified implementation of the AS is obtained. Finally the definiteness and uniqueness of the estimator are analyzed.     

利用Cre/loxP位点特异性重组酶系统从转基因植物生产非转基因食品

转基因植物中的外源基因是引起转基因植物食品安全性问题的主要原因。通过对Cre／loxP系统介导转基因植物中外源基因选择性切除的最新研究成果进行综述分析,指出利用果实、花粉等组织特异性启动子对重组酶基因的表达进行调控,将转基因植物食用部位的外源基因选择性的切除,是将转基因植物转化为非转基因食品的一条有效途径。     

非小细胞肺癌患者ERCC1表达与铂类药物化疗敏感性的相关性的系统分析

目的: 分析非小细胞肺癌患者切除修复交叉互补基因1(ERCC1)表达与对铂类药物治疗敏感性的相关性。方法: 电子检索Medline(1991.1-2009.12)、Pubmed、CBMDisc等数据库,对回顾性病例研究和随机对照临床试验进行总结分析。结果: 共纳入10篇文献,包括9篇回顾性病例研究和1篇随机对照临床试验。9篇回顾性病例研究资料中,7篇结果表明ERCC1表达阴性患者对铂类药物的联合化疗方案的反应率高于阳性患者(2篇结果具有统计学意义),另2篇ERCC1表达阴性患者对铂类药物的联合化疗方案的反应率低于阳性患者;1篇文献报道化疗后肿瘤进展时间ERCC1阴性组患者显著长于ERCC1阳性组患者(P<0.05);化疗后中位生存期具有统计学差异的2篇报道均为ERCC1阴性组高于ERCC1阳性组 (P<0.05)。RCT研究结果表明辅助化疗可以明显延长ERCC1阴性患者的生存期,但不能延长ERCC1阳性患者的生存期。结论: 非小细胞肺癌患者中ERCC1低表达者可以从铂类化疗方案中受益,高表达者对铂类药物的化疗敏感性差,需要更好的辅助治疗方案。ERCC1作为预测NSCLC对铂类药物化疗方案敏感性的指标并指导临床个体化治疗具有临床意义。     

Development and testing of a prototype automatic trim sampler

The N60 method currently mandated by regulatory bodies in North America for routine testing of beef trim for Escherichia coli O157:H7 requires that 60 slices of beef, up to 375 g, be removed from combo bins containing up to 10,000 lb of beef trim. The objective of this study was to design and test a prototype automatic trim sampler that would reduce the resource demands of, and result in more representative sampling than, N60. Ten commercial combo bins were each sampled at five locations of each of four levels, by swabbing an area of 1000 cm² and by excision of up to five meat pieces with a total area of 100 cm². The samples were enriched in modified Tryptone Soy Broth supplemented with novobiocin at 20 mg/L, and tested for generic E. coli using real-time PCR. A prototype trim sampler was constructed and tested for recovery of aerobes, coliforms and E. coli and was compared to manual swabbing, using beef trim artificially contaminated with E. coli. Overall, 21.5% of excision samples and 38.0% of swab samples from combo bins were positive for E. coli. Of the 40 levels that were sampled, 50.0% were positive by excision, 70.0% were positive by swabbing. The sampler, designed based on swab sampling, could process trim of ≤1 kg. Of the 12 pairs of manual sampling and automatic sampling compared, ≥ 8 were not significantly different for recovering each of the three groups of indicator organisms (P > 0.05). The findings of this study show that swab sampling can be more sensitive and representative than excision sampling for recovering small numbers of E. coli from beef trim and the prototype sampler can have efficacy comparable to manual swabbing for recovering all three groups of indicator organisms from beef.     

Chromatin Dynamics during Nucleotide Excision Repair: Histones on the Move

It has been a long-standing question how DNA damage repair proceeds in a nuclear environment where DNA is packaged into chromatin. Several decades of analysis combining in vitro and in vivo studies in various model organisms ranging from yeast to human have markedly increased our understanding of the mechanisms underlying chromatin disorganization upon damage detection and re-assembly after repair. Here, we review the methods that have been developed over the years to delineate chromatin alterations in response to DNA damage by focusing on the well-characterized Nucleotide Excision Repair (NER) pathway. We also highlight how these methods have provided key mechanistic insight into histone dynamics coupled to repair in mammals, raising new issues about the maintenance of chromatin integrity. In particular, we discuss how NER factors and central players in chromatin dynamics such as histone modifiers, nucleosome remodeling factors, and histone chaperones function to mobilize histones during repair.     

耐辐射球菌Deinococcus radiodurans辐射抗性的研究进展

耐辐射球菌（Deinococcus radiodurans）是迄今为止发现的对电离辐射、紫外线、过氧化氢等一些DNA损伤剂都具有极强抗性的微小球菌，研究表明，这种独特抗性归因于其具有高效而准确的DNA修复系统。公认的耐辐射球菌有3种DNA修复方式：碱基切除修复、核苷酸切除修复和重组修复。对于耐辐射球菌是否具有SOS易错修复尚存争议，染色体DNA的降解和排除细胞外有利于DNA修复的正确和顺利进行，但DNA修复过程的分子柚是了解却甚少。     

Alzheimer’s Disease-Associated Neurotoxic Peptide Amyloid-β Impairs Base Excision Repair in Human Neuroblastoma Cells

Alzheimer’s disease (AD) is the leading cause of dementia in developed countries. It is characterized by two major pathological hallmarks, one of which is the extracellular aggregation of the neurotoxic peptide amyloid-β (Aβ), which is known to generate oxidative stress. In this study, we showed that the presence of Aβ in a neuroblastoma cell line led to an increase in both nuclear and mitochondrial DNA damage. Unexpectedly, a concomitant decrease in basal level of base excision repair, a major route for repairing oxidative DNA damage, was observed at the levels of both gene expression and protein activity. Moreover, the addition of copper sulfate or hydrogen peroxide, used to mimic the oxidative stress observed in AD-affected brains, potentiates Aβ-mediated perturbation of DNA damage/repair systems in the “Aβ cell line”. Taken together, these findings indicate that Aβ could act as double-edged sword by both increasing oxidative nuclear/mitochondrial damage and preventing its repair. The synergistic effects of increased ROS production, accumulated DNA damage and impaired DNA repair could participate in, and partly explain, the massive loss of neurons observed in Alzheimer’s disease since both oxidative stress and DNA damage can trigger apoptosis.