Aorta-to-right atrium fistula, an unusual complication of endocarditis

Infective endocarditis (IE) remains a serious disease. Aorta-to-right atrium fistula is a rare but very serious complication of IE and predicts a higher mortality. This report describes a 50-year-old man with endocarditis, vegetation, perforation of noncoronary sinus, and formation of two aorta-to-right atrium fistulas with native valves detected by transthoracic echocardiography. This disease is lethal despite developments in cardiac imaging and antibacterial therapy. Early diagnosis, aggressive antibacterial therapy, and surgical treatment may improve the prognosis.     

一种开源语法检查器的改进

选择基于统计的开源Masaru语法检查器为研究对象,分析技术路线与功能特点,提出了增加3元4元模型方法,并在系统中实现了3元4元语言模型.实验结果表明,改进的语法检查器准确度达到了81%,与原系统相比提高了6个百分点.     

Fungal defensins,an emerging source of anti-infective drugs

With the rapid increase of antibiotic-resistantpathogens and the decline of discovery and development ofnew antibiotics, there is an urgent need to exploit alterna-tive anti-infective drugs. Fungal defensin-like peptides areemerging as a class of new source of anti-infective drugsdue to their potent antibacterial activity, low toxicity, andhigh serum stability. Fungal genome sequencing projectscombined with the development of recombinant expressiontechniques will accelerate the discovery of fungal defensin-like peptides.     

Landfill is an important atmospheric mercury emission source

Due to the special physical and chemical properties,mercury is a global pollutant which could be aeriallytransported cross the borders[1,2]. Both natural processesand human activities emit mercury to the air. The majoranthropogenic mercury emission source categories arecoal combustion, waste incineration, chlorine-alkali plant,metal smelting and refining and so on[1—3] . Human activi-ties emit not only elemental mercury (Hg0), which has along lifetime in the air, but also reactive gaseous mer…     

Structure of the sulphiredoxin-peroxiredoxin complex reveals an essential repair embrace

Typical 2-Cys peroxiredoxins (Prxs) have an important role in regulating hydrogen peroxide-mediated cell signalling. In this process, Prxs can become inactivated through the hyperoxidation of an active site Cys residue to Cys sulphinic acid. The unique repair of this moiety by sulphiredoxin (Srx) restores peroxidase activity and terminates the signal. The hyperoxidized form of Prx exists as a stable decameric structure with each active site buried. Therefore, it is unclear how Srx can access the sulphinic acid moiety. Here we present the 2.6 A crystal structure of the human Srx-PrxI complex. This complex reveals the complete unfolding of the carboxy terminus of Prx, and its unexpected packing onto the backside of Srx away from the Srx active site. Binding studies and activity analyses of site-directed mutants at this interface show that the interaction is required for repair to occur. Moreover, rearrangements in the Prx active site lead to a juxtaposition of the Prx Gly-Gly-Leu-Gly and Srx ATP-binding motifs, providing a structural basis for the first step of the catalytic mechanism. The results also suggest that the observed interactions may represent a common mode for other proteins to bind to Prxs.     

Genomic analysis of metastasis reveals an essential role for RhoC

The most damaging change during cancer progression is the switch from a locally growing tumour to a metastatic killer. This switch is believed to involve numerous alterations that allow tumour cells to complete the complex series of events needed for metastasis. Relatively few genes have been implicated in these events. Here we use an in vivo selection scheme to select highly metastatic melanoma cells. By analysing these cells on DNA arrays, we define a pattern of gene expression that correlates with progression to a metastatic phenotype. In particular, we show enhanced expression of several genes involved in extracellular matrix assembly and of a second set of genes that regulate, either directly or indirectly, the actin-based cytoskeleton. One of these, the small GTPase RhoC, enhances metastasis when overexpressed, whereas a dominant-negative Rho inhibits metastasis. Analysis of the phenotype of cells expressing dominant-negative Rho or RhoC indicates that RhoC is important in tumour cell invasion. The genomic approach allows us to identify families of genes involved in a process, not just single genes, and can indicate which molecular and cellular events might be important in complex biological processes such as metastasis.     

Angiotensin-converting enzyme 2 is an essential regulator of heart function

Cardiovascular diseases are predicted to be the most common cause of death worldwide by 2020. Here we show that angiotensin-converting enzyme 2 (ace2) maps to a defined quantitative trait locus (QTL) on the X chromosome in three different rat models of hypertension. In all hypertensive rat strains, ACE2 messenger RNA and protein expression were markedly reduced, suggesting that ace2 is a candidate gene for this QTL. Targeted disruption of ACE2 in mice results in a severe cardiac contractility defect, increased angiotensin II levels, and upregulation of hypoxia-induced genes in the heart. Genetic ablation of ACE on an ACE2 mutant background completely rescues the cardiac phenotype. But disruption of ACER, a Drosophila ACE2 homologue, results in a severe defect of heart morphogenesis. These genetic data for ACE2 show that it is an essential regulator of heart function in vivo.     

arrow encodes an LDL-receptor-related protein essential for Wingless signalling

The Wnt family of secreted molecules functions in cell-fate determination and morphogenesis during development in both vertebrates and invertebrates (reviewed in ref. 1). Drosophila Wingless is a founding member of this family, and many components of its signal transduction cascade have been identified, including the Frizzled class of receptor. But the mechanism by which the Wingless signal is received and transduced across the membrane is not completely understood. Here we describe a gene that is necessary for all Wingless signalling events in Drosophila. We show that arrow gene function is essential in cells receiving Wingless input and that it acts upstream of Dishevelled. arrow encodes a single-pass transmembrane protein, indicating that it may be part of a receptor complex with Frizzled class proteins. Arrow is a low-density lipoprotein (LDL)-receptor-related protein (LRP), strikingly homologous to murine and human LRP5 and LRP6. Thus, our data suggests a new and conserved function for this LRP subfamily in Wingless/Wnt signal reception.     

Hydrogen is an energy source for hydrothermal vent symbioses

The discovery of deep-sea hydrothermal vents in 1977 revolutionized our understanding of the energy sources that fuel primary productivity on Earth. Hydrothermal vent ecosystems are dominated by animals that live in symbiosis with chemosynthetic bacteria. So far, only two energy sources have been shown to power chemosynthetic symbioses: reduced sulphur compounds and methane. Using metagenome sequencing, single-gene fluorescence in situ hybridization, immunohistochemistry, shipboard incubations and in situ mass spectrometry, we show here that the symbionts of the hydrothermal vent mussel Bathymodiolus from the Mid-Atlantic Ridge use hydrogen to power primary production. In addition, we show that the symbionts of Bathymodiolus mussels from Pacific vents have hupL, the key gene for hydrogen oxidation. Furthermore, the symbionts of other vent animals such as the tubeworm Riftia pachyptila and the shrimp Rimicaris exoculata also have hupL. We propose that the ability to use hydrogen as an energy source is widespread in hydrothermal vent symbioses, particularly at sites where hydrogen is abundant.     

镅铍源硼中子γ测井的可行性

为降低测井成本,用镅铍源取代脉冲中子源,研究在储层已注入硼酸溶液的条件下进行中子γ测井即硼中子γ测井的可行性。用Monte-Carlo模拟技术即通用程序MCNP(3B),计算了该测井方法的俘获γ能谱、俘获γ计数与含水饱和度及源距的关系。得出了俘获γ计数随含水饱和度的增加呈指数规律衰减;井眼对俘获γ计数的影响很小,而且俘获γ计数与地层孔隙度具有良好的相关性。从计算结果看,用镅铍源取代脉冲中子源进行硼中子γ测井是可行的,其适应性强,成本低。