Noradrenaline hyperalgesia is mediated through interaction with sympathetic postganglionic neurone terminals rather than activation of primary afferent nociceptors

In hyperalgesic states, observed commonly as a major symptom of tissue inflammation or after central or peripheral nerve injury, non-noxious stimuli produce pain and noxious stimuli are perceived as more painful than usual. The mechanisms underlying the generation of hyperalgesia are not known. In patients with causalgia (burning pain and severe hyperalgesia after a nerve injury) activation of sympathetic post-ganglionic neurones or application of noradrenaline to painful skin exacerbates pain and hyperalgesia while sympathectomy may afford complete relief. One suggestion is that noradrenaline released from sympathetic post-ganglionic neurons increases the discharge of damaged small-diameter afferents by a direct action on the primary afferents. Here we present a new model for noradrenaline-sensitive hyperalgesia and demonstrate that the site of action of noradrenaline is not on the primary afferents but rather is presynaptic on the sympathetic post-ganglionic terminals.     

大型结构振动分析的快速矩阵指数法

提出了快速矩阵指数法，并将它应用于大型结构的振动分析．以高层建筑为对象，分别计算了10层和30层楼房在外激励作用下的位移响应，在快速矩阵指数法中，每一时间步长是其前一时间步长的2倍．而且能够提供较多的系统信息．实例计算表明，该方法收敛速度快、计算效率高、具有良好的精确度。     

活性染料废水对环境污染程度的预测

近年来,公众对保护环境的意识不断提高,因而令政府更关注环境污染的问题。为了保障市民的健康及保护生态环境,香港政府便制订了更严格的环保法例及废水排放标准,因此在染色时,厂商不但需要考虑染色成本及产品的坚牢度,更要考虑染料的环境属性,从而减低染色废水对环境的污染及符合政府制订的排放标准。如果能对染料的环境属性预先进行评估,那么染色废水对环境污染的程度便可于染色前预测得到,从而可于染色前选择一些污染度较低的染料进行染色。但由于不同染料类别的废水有不同的特性,因此,在这研究内,我们便选择了活性染料作为分析对象。     

Water exchange between the subglacial Lake Vostok and the overlying ice sheet

It has now been known for several years that a 200-km-long lake, called Lake Vostok, lies beneath the ice sheet on which sits Vostok Station in Antarctica. The conditions at the base of the ice sheet above this subglacial lake can provide information about the environment within the lake, including the likelihood that it supports life. Here we present an analysis of the ice-sheet structure from airborne 60-MHz radar studies, which indicates that distinct zones of basal ice loss and accretion occur at the ice-water interface. Subglacial melting and net ice loss occur in the north of the lake and across its 200-km-long western margin, whereas about 150 m of ice is gained by subglacial freezing in the south. This indicates that significant quantities of water are exchanged between the base of the ice sheet and the lake waters, which will enrich the lake with gas hydrates, cause sediment deposition and encourage circulation of the lake water.     

A map of human genome sequence variation containing 1.42 million single nucleotide polymorphisms

We describe a map of 1.42 million single nucleotide polymorphisms (SNPs) distributed throughout the human genome, providing an average density on available sequence of one SNP every 1.9 kilobases. These SNPs were primarily discovered by two projects: The SNP Consortium and the analysis of clone overlaps by the International Human Genome Sequencing Consortium. The map integrates all publicly available SNPs with described genes and other genomic features. We estimate that 60,000 SNPs fall within exon (coding and untranslated regions), and 85% of exons are within 5 kb of the nearest SNP. Nucleotide diversity varies greatly across the genome, in a manner broadly consistent with a standard population genetic model of human history. This high-density SNP map provides a public resource for defining haplotype variation across the genome, and should help to identify biomedically important genes for diagnosis and therapy.     

Effect of Splice Marking on Fabric Roll Planning

Minimising the fabric loss during spreading can reduce the total production costs of garment manufacturing. Although marker planning is a major determinant of material utilisation, considerable savings on materials also will be made from the area of spreading loss. In the spreading process, it is general to have variance on the fabric yardage between each fabric roll, and the number of splice markings on each cutting lay is also varied. This paper aim to study how the fabric roll planning and the number of splice marks of a cutting lay will affect the material usage in the spreading process. By using a genetic algorithm approach, the amount of fabric to be saved by optimising the fabric roll sequence was derived by comparing the best arrangement and the worst arrangement of the fabric roll sequences of a cutting lay. The result of the study showed that both fabric roll planning and the number of splice marking have effect on the fabric loss. The findings could help the apparel manufacturer to reduce the     

Structure of the spliceosomal U4 snRNP core domain and its implication for snRNP biogenesis

The spliceosome is a dynamic macromolecular machine that assembles on pre-messenger RNA substrates and catalyses the excision of non-coding intervening sequences (introns). Four of the five major components of the spliceosome, U1, U2, U4 and U5 small nuclear ribonucleoproteins (snRNPs), contain seven Sm proteins (SmB/B', SmD1, SmD2, SmD3, SmE, SmF and SmG) in common. Following export of the U1, U2, U4 and U5 snRNAs to the cytoplasm, the seven Sm proteins, chaperoned by the survival of motor neurons (SMN) complex, assemble around a single-stranded, U-rich sequence called the Sm site in each small nuclear RNA (snRNA), to form the core domain of the respective snRNP particle. Core domain formation is a prerequisite for re-import into the nucleus, where these snRNPs mature via addition of their particle-specific proteins. Here we present a crystal structure of the U4 snRNP core domain at 3.6?? resolution, detailing how the Sm site heptad (AUUUUUG) binds inside the central hole of the heptameric ring of Sm proteins, interacting one-to-one with SmE-SmG-SmD3-SmB-SmD1-SmD2-SmF. An irregular backbone conformation of the Sm site sequence combined with the asymmetric structure of the heteromeric protein ring allows each base to interact in a distinct manner with four key residues at equivalent positions in the L3 and L5 loops of the Sm fold. A comparison of this structure with the U1 snRNP at 5.5?? resolution reveals snRNA-dependent structural changes outside the Sm fold, which may facilitate the binding of particle-specific proteins that are crucial to biogenesis of spliceosomal snRNPs.     

双酚A对微小小环藻的毒性效应

以微小小环藻(Cyclotella caspia)为测试藻种,研究了不同浓度的双酚A对微小小环藻的急性毒性效应。在双酚A(4,6,8,10,12 mg/L)作用下,藻细胞生长受到不同程度的抑制;藻细胞叶绿素a含量随着双酚A浓度的增加呈下降趋势;藻细胞SOD活性随着双酚A浓度和作用时间的变化基本呈现为从诱导到抑制的动态过程;4~6 mg/L双酚A对藻细胞形态影响不大,8~12 mg/L双酚A可导致藻细胞不易分裂,细胞体积增大,细胞内含物增多,细胞器受到不同程度的破坏。