Evidence of the activity of dissimilatory sulfate-reducing prokaryotes in nonsulfidogenic tropical mobile muds

In spite of the nonsulfidic conditions and abundant reactive iron(III) commonly found in mobile tropical deltaic muds, genes encoding dissimilatory sulfite reductase (dsr) were successfully amplified from the upper approximately 1 m of coastal deposits sampled along French Guiana and in the Gulf of Papua. The dsr sequences retrieved were highly diverse, were generally represented in both study regions and fell into six large phylogenetic groupings: Deltaproteobacteria, Thermodesulfovibrio groups, Firmicutes and three groups without known cultured representatives. The spatial and temporal distribution of dsr sequences strongly supports the contention that the sulfate-reducing prokaryote communities in mobile mud environments are cosmopolitan and stable over a period of years. The decrease in the (35)SO(4) (2-) tracer demonstrates that, despite abundant reactive sedimentary iron(III) ( approximately 350-400 mumol g(-1)), the sulfate-reducing prokaryotes present are active, with the highest levels of sulfide being generated in the upper zones of the cores (0-30 cm). Both the time course of the (35)S-sulfide tracer activity and the lack of reduced sulfur in sediments demonstrate virtually complete anaerobic loss of solid phase sulfides. We propose a pathway of organic matter oxidation involving at least 5-25% of the remineralized carbon, wherein sulfide produced by sulfate-reducing prokaryotes is cyclically oxidized biotically or abiotically by metal oxides.     

形状记忆合金超弹性自扩张血管支架的优化设计

自扩张型镍钛合金血管支架由于其良好的生物相容性与超弹性,可以很好地解决支架植入后的再狭窄问题。利用有限元软件ANSYS对支架在血管中的自扩张行为进行模拟,并对支架的网格形状与尺寸进行优化设计。     

Molecular cloning and characterization of a plant alpha1,3/4-fucosidase based on sequence tags from almond fucosidase I

Our work with almond peptide N-glycosidase A made us interested also in the alpha1,3/4-fucosidase which is used as a specific reagent for glycoconjugate analysis. The enzyme was purified to presumed homogeneity by a series of chromatographic steps including dye affinity and fast-performance anion exchange chromatography. The 63 kDa band was analyzed by tandem mass spectrometry which yielded several partial sequences. A homology search retrieved the hypothetical protein Q8GW72 from Arabidopsis thaliana. This protein has recently been described as being specific for alpha1,2-linkages. However, cDNA cloning and expression in Pichia pastoris of the A. thaliana fucosidase showed that it hydrolyzed fucose in 3- and 4-linkage to GlcNAc in Lewis determinants whereas neither 2-linked fucose nor fucose in 3-linkage to the innermost GlcNAc residue were attacked. This first cloning of a plant alpha1,3/4-fucosidase also confirmed the identity of the purified almond enzyme and thus settles the notorious uncertainty about its molecular mass. The alpha1,3/4-fucosidase from Arabidopsis exhibited striking sequence similarity with an enzyme of similar substrate specificity from Streptomyces sp. (Q9Z4I9) and with putative proteins from rice.     

植入雷帕霉素药物支架长度对围手术期心肌梗死的预测研究

目的:评估植入支架长度对围手术期心肌梗死的预测意义。方法:选择2005年6月到2009年2月解放军第454医院医院及长海医院341名冠心病患者,共植入351枚雷帕霉素药物支架,根据植入支架数目分为单个支架组(22-36mm)及重叠支架组(>36mm);根据植入支架长度分四组:①28-36mm②37-59mm③60-80mm④>80mm。观察支架植入后的急性并发症,术后心电图变化和术后1周内心肌肌钙蛋白的变化。结果:1.手术成功率达98.9%,急性并发症发生率为6.1%。住院期间主要不良心血管事件(MACE)发生率达到14.1%。2.根据植入单个支架组与重叠支架组比较,重叠支架组(>36mm)术后肌钙蛋白I(TNI)显著高于单个支架组(22-36mm):6.0%VS1.1%,P<0.05;而在住院期间MACE发生率上前者也明显高于后者:11.6%VS5.6%,P<0.05。3.在支架长度分组中发现支架长度>60mm组发生围手术期并发症及MACE事件明显高于28-36mm组,P<0.05;其余组间未见显著差异。结论:重叠支架植入方法及植入支架长度>60mm明显增加术后心肌损伤标志物释放,增加围手术期非Q波心肌梗死...     

Liposome Coated Stents: A Method to Deliver Drugs to the Site of Action and Improve Stent Blood-Compatibility

Abstract

N-(phosphonacetyl)-L-aspartic acid (PALA) exhibits a considerable increase in its in vitro growth inhibitory potency when it is incorporated into liposomes. Encapsulation in negatively charged liposomes increases the growth inhibitory potency of PALA by up to 360 times. For CV1-P and L929 cells, encapsulation in liposomes prepared from neutral phospholipids does not increase the potency of PALA. the potency of encapsulated PALA is not dependent on the size of liposomes, being equally effective in all liposomes between 0.1 and 1 µm in diameter. the potency of PALA is greatest when it is incorporated into liposomes prepared from high phase transition temperature lipids. Exposure of cells to 7.5 mM ammonium chloride substantially inhibits the effects of both free and encapsulated PALA. the potency of free PALA is more sensitive to changes in exposure length than is the potency of encapsulated PALA. Consequently the difference in potency between free and encapsulated PALA is greatest when exposure length is short (1-2 hr). the considerable potency of encapsulated PALA makes this drug a possible treatment for tumors and ocular cicatricial diseases.     

α-Syntrophin is required for the hepatocyte growth factor-induced migration of cultured myoblasts

Syntrophins are adaptor proteins that link intracellular signaling molecules to the dystrophin based scaffold. In this study, we investigated the function of syntrophins in cell migration, one of the early steps in myogenic differentiation and in regeneration of adult muscle. Hepatocyte growth factor (HGF) stimulates migration and lamellipodia formation in cultured C2 myoblasts. In the migrating cells, syntrophin concentrated in the rear-lateral region of the cell, opposite of the lamellipodia, instead of being diffusely present throughout the cytoplasm of non-migrating cells. When the expression of α-syntrophin, the major syntrophin isoform of skeletal muscle, was reduced by transfection with the α-syntrophin-specific siRNA, HGF stimulation of lamellipodia formation was prevented. Likewise, migration of myoblasts from α-syntrophin knockout mice could not be stimulated by HGF. However, HGF-induced migration was restored in myoblasts isolated from a transgenic mouse expressing α-syntrophin only in muscle cells. Treatment of C2 myoblasts with inhibitors of PI3-kinase not only reduced the rate of cell migration, but also impaired the accumulation of syntrophins in the rear-lateral region of the migrating cells. Phosphorylation of Akt was reduced in the α-syntrophin siRNA-treated C2 cells. These results suggest that α-syntrophin is required for HGF-induced migration of myoblasts and for proper PI3-kinase/Akt signaling.     

Bistable responses in bacterial genetic networks: designs and dynamical consequences

A key property of living cells is their ability to react to stimuli with specific biochemical responses. These responses can be understood through the dynamics of underlying biochemical and genetic networks. Evolutionary design principles have been well studied in networks that display graded responses, with a continuous relationship between input signal and system output. Alternatively, biochemical networks can exhibit bistable responses so that over a range of signals the network possesses two stable steady states. In this review, we discuss several conceptual examples illustrating network designs that can result in a bistable response of the biochemical network. Next, we examine manifestations of these designs in bacterial master-regulatory genetic circuits. In particular, we discuss mechanisms and dynamic consequences of bistability in three circuits: two-component systems, sigma-factor networks, and a multistep phosphorelay. Analyzing these examples allows us to expand our knowledge of evolutionary design principles networks with bistable responses.     

Impact of Coronary Artery Curvature on the Longitudinal Stent Foreshortening: Real-World Observations

Longitudinal stent foreshortening is a known phenomenon, however, the impact of coronary artery curvature on longitudinal stent foreshortening remains unclear. The aim of this study is to determine the impact of coronary artery curvature on the longitudinal stent foreshortening in the real-world scenarios. A total of 86 consecutive patients underwent coronary stent implantation were included in the present study. The degree of coronary artery curvature was defined as the length of the coronary artery curvature divided by the straight length. Longitudinal stent foreshortening was defined as the stent length after implantation divided by the stent length before implantation. The mean longitudinal foreshortening rate of coronary stents was about 94% in curved coronary arteries. Longitudinal stent foreshortening rate was positively correlated with the degree of coronary artery curvature (r = –0.86, P < 0.01). Coronary artery curvature is associated with significant longitudinal foreshortening of coronary stents, thus longitudinal foreshortening should be considered on deciding the stent length in curved coronary artery and a longer stent is usually needed in curved coronary artery.     

金属血管支架的制备及影响因素

简要概述了血管支架的制备过程.从激光器和加工材料的选择,支架结构的设计,激光切割工艺参数的优化,辅助路径的设置以及血管支架的后序处理等方面探讨了这些因素对血管支架加工质量的影响情况.