556例多发伤患者的急诊救治临床分析

目的探讨多发伤患者的救治策略。方法回顾分析我科2000年1月至2008年5月急诊抢救的556例多发伤患者的临床资料。结果 16例患者经抢救无效死亡,死亡率2.88%;其余患者均经紧急抢救及行必要实验室检查,病情稳定,好转率达97.12%。平均抢救时间为(1.37±1.05)h。结论强化多发伤的急诊科早期救治,树立创伤急救"黄金1 h"观念,是提高多发伤患者生存率及降低死亡率的关键。     

Tumour necrosis factor-α stimulates human neutrophils to release preformed activin A

Activin A, a member of the transforming growth factor-β superfamily, is a critical early mediator of acute inflammation. Activin A release coincides with the release of tumour necrosis factor-α (TNF-α) in models of lipopolysaccharide (LPS)-induced inflammation. The source of circulating activin A during acute inflammation has not been identified and the potential contribution of leukocyte subsets was examined in the following study. Human leukocytes from healthy volunteers were fractionated using Ficoll gradients and cultured under serum-free conditions. Freshly isolated human neutrophils contained 20-fold more activin A than blood mononuclear cells as measured by enzyme-linked immunosorbent assay (ELISA), and both dimeric and monomeric forms of activin A were detected in these cells by western blotting. Activin A was predominantly immunolocalized in the neutrophil cytoplasm. Purified neutrophils secreted activin A in culture when stimulated by TNF-α, but were unable to respond to LPS directly. Although TNF-α stimulated activin A release from neutrophils within 1 h, activin subunit mRNA expression did not increase until 12 h of culture, and the amount of activin A released following TNF-α stimulation did not change between 1 and 12 h. Specific inhibition of the p38 MAP kinase signalling pathway blocked TNF-α-induced activin release, and the secretion of activin A was not due to TNF-α-induced neutrophil apoptosis. These data provide the first evidence that neutrophils are a significant source of mature, stored activin A. Stimulation of the release of neutrophil activin A by TNF-α may contribute to the early peak in circulating activin A levels during acute inflammation.     

Evidence for widespread reticulate evolution within human duplicons

Approximately 5% of the human genome consists of segmental duplications that can cause genomic mutations and may play a role in gene innovation. Reticulate evolutionary processes, such as unequal crossing-over and gene conversion, are known to occur within specific duplicon families, but the broader contribution of these processes to the evolution of human duplications remains poorly characterized. Here, we use phylogenetic profiling to analyze multiple alignments of 24 human duplicon families that span >8 Mb of DNA. Our results indicate that none of them are evolving independently, with all alignments showing sharp discontinuities in phylogenetic signal consistent with reticulation. To analyze these results in more detail, we have developed a quartet method that estimates the relative contribution of nucleotide substitution and reticulate processes to sequence evolution. Our data indicate that most of the duplications show a highly significant excess of sites consistent with reticulate evolution, compared with the number expected by nucleotide substitution alone, with 15 of 30 alignments showing a >20-fold excess over that expected. Using permutation tests, we also show that at least 5% of the total sequence shares 100% sequence identity because of reticulation, a figure that includes 74 independent tracts of perfect identity >2 kb in length. Furthermore, analysis of a subset of alignments indicates that the density of reticulation events is as high as 1 every 4 kb. These results indicate that phylogenetic relationships within recently duplicated human DNA can be rapidly disrupted by reticulate evolution. This finding has important implications for efforts to finish the human genome sequence, complicates comparative sequence analysis of duplicon families, and could profoundly influence the tempo of gene-family evolution.     

Novel role for decay-accelerating factor in coxsackievirus A21-mediated cell infectivity

Decay-accelerating factor (DAF) is involved in the cell membrane attachment of many human enteroviruses. Presently, further specific active roles of DAF in mediating productive cell infection and in the pathogenesis of natural enterovirus infection are poorly understood. In an attempt to more fully understand the role of DAF in lytic cell infection we examined the specific interactions of the prototype strain of coxsackievirus A21 (CVA21) with surface-expressed DAF. Investigations into discrete DAF-CVA21 interactions focused on viral binding; viral particle elution with respect to the parameters of time, temperature, and pH; and subsequent cell infection. Radiolabeled-virus binding assays revealed that peak elution of CVA21 from DAF occurred within 15 min of initial attachment and that the DAF-eluted virus increased in a linear fashion with respect to temperature and pH. CVA21 eluted from endogenous surface-expressed DAF was highly infectious, in contrast to CVA21 eluted from intercellular adhesion molecule 1 (ICAM-1), which retained little to no infectivity. Using an adenovirus transduction system, we demonstrate that CVA21 can remain infectious for up to 24 h after DAF binding and is capable of initiating a multicycle lytic infection upon delayed ICAM-1 surface expression. Taken together, the data suggest that a major role of DAF in cell infection by the prototype strain of CVA21 is to provide membrane concentration of infectious virions, effectively increasing viral interactions with endogenous or induced ICAM-1.     

By any other name: heterologous replacement of the Escherichia coli RNase P protein subunit has in vivo fitness consequences

Bacterial RNase P is an essential ribonucleoprotein composed of a catalytic RNA component (encoded by the rnpB gene) and an associated protein moiety (encoded by rnpA). We construct a system that allows for the deletion of the essential endogenous rnpA copy and for its simultaneous replacement by a heterologous version of the gene. Using growth rate as a proxy, we explore the effects on fitness of heterologous replacement by increasingly divergent versions of the RNase P protein. All of the heterologs tested complement the loss of the endogenous rnpA gene, suggesting that all existing bacterial versions of the rnpA sequence retain the elements required for functional interaction with the RNase P RNA. All replacements, however, exact a cost on organismal fitness, and particularly on the rate of growth acceleration, defined as the time required to reach maximal growth rate. Our data suggest that the similarity of the heterolog to the endogenous version--whether defined at the sequence, structure or codon usage level--not predict the fitness costs of the replacement. The common assumption that sequence similarity predicts functional similarity requires experimental confirmation and may prove to be an oversimplification.     

Single-molecule analysis of DNA replication in Xenopus egg extracts

The recent advent in single-molecule imaging and manipulation methods has made a significant impact on the understanding of molecular mechanisms underlying many essential cellular processes. Single-molecule techniques such as electron microscopy and DNA fiber assays have been employed to study the duplication of genome in eukaryotes. Here, we describe a single-molecule assay that allows replication of DNA attached to the functionalized surface of a microfluidic flow cell in a soluble Xenopus leavis egg extract replication system and subsequent visualization of replication products via fluorescence microscopy. We also explain a method for detection of replication proteins, through fluorescently labeled antibodies, on partially replicated DNA immobilized at both ends to the surface.     

Sporogenesis in Eusporangiate Ferns: II. Polyplastidic Meiosis in Ophioglossum (Ophioglossales)

Ophioglossum petiolatum . Unlike Angiopteris (Marattiales), which is monoplastidic, Ophioglossum undergoes polyplastidic meiosis like members of the fern-seed plant clade. The meiotic spindle is distinctly multipolar in origin and is consolidated into a bipolar spindle that is variously twisted and curved to accommodate the large number of chromosomes. Although a phragmoplast forms after first meiosis, no wall is deposited. Instead, an organelle band consisting of intermingled plastids and mitochondria is formed in the equatorial region between the dyad domains. Following second meiosis, a complex of phragmoplasts forms among sister and non-sister nuclei. Cell plates are deposited first between sister nuclei and then in the region of the organelle band resulting in a tetrad of spores each with a equal allotment of organelles. Received 30 January 2001/ Accepted in revised form 24 April 2001     

Flux Analysis of Glucose Metabolism in Rhizopus oryzae for the Purpose of Increasing Lactate Yields

A flux analysis of glucose metabolism in the filamentous fungus Rhizopus oryzae was achieved using a specific radioactivity curve-matching program, TFLUX. Glycolytic and tricarboxylic acid cycle intermediates labeled through the addition of extracellular [U-14C]glucose were isolated and purified for specific radioactivity determinations. This information, together with pool sizes and the rates of glucose utilization and end product production, provided input for flux maps of the metabolic network under two different experimental conditions. Based upon the flux analysis of this system, a mutant of R. oryzae with higher lactate and lower ethanol yields than the parent was sought for and found.