Deleted in colorectal carcinoma suppresses metastasis in p53-deficient mammary tumours

Since its discovery in the early 1990s the deleted in colorectal cancer (DCC) gene, located on chromosome 18q21, has been proposed as a tumour suppressor gene as its loss is implicated in the majority of advanced colorectal and many other cancers. DCC belongs to the family of netrin 1 receptors, which function as dependence receptors as they control survival or apoptosis depending on ligand binding. However, the role of DCC as a tumour suppressor remains controversial because of the rarity of DCC-specific mutations and the presence of other tumour suppressor genes in the same chromosomal region. Here we show that in a mouse model of mammary carcinoma based on somatic inactivation of p53, additional loss of DCC promotes metastasis formation without affecting the primary tumour phenotype. Furthermore, we demonstrate that in cell cultures derived from p53-deficient mouse mammary tumours DCC expression controls netrin-1-dependent cell survival, providing a mechanistic basis for the enhanced metastatic capacity of tumour cells lacking DCC. Consistent with this idea, in vivo tumour-cell survival is enhanced by DCC loss. Together, our data support the function of DCC as a context-dependent tumour suppressor that limits survival of disseminated tumour cells.     

宁夏贺兰山东麓扬黄新灌区土壤质量的演变

为系统认识宁夏贺兰山东麓扬黄新灌区土地在利用变化背景下,土壤质量演变的一般规律,用空间换时间的田间取样方法,分别从利用方式、土壤分层、利用年限的角度构建数据体系.结果表明,相对未利用对照地,耕地土壤中有机碳和盐分发生表聚现象,园地20～60cm土层中有机碳和盐分明显富集;随利用年限的延长,早期耕地和园地表层中有机碳和盐分含量都呈现先降后升的格局,但后期变化趋势出现分异.园地和耕地表层土壤中wC/N,wC/P随利用年限的延长表现出近似的变化趋势,但后期土壤中wC/N开始趋近于未利用对照地,土壤中C-N循环并未发生实质性改变.耕地、园地各自具有其独特的土地退化防治价值,但是园地具有更突出的生态适宜性,耕地长期利用下的次生退化问题依然需要关注.     

蚕丝蛋白仿生多肽RAGA16的纳米结构与性能研究

利用天然蛋白质氨基酸序列设计生物仿生材料是近年来兴起的一个热门研究领域.本文中将蚕丝蛋白特征氨基酸序列(Gly-Ala-Gly-Ala-Gly-Ser)部分引入离子互补型多肽RA-DA16-Ⅰ中,设计了新型多肽RAGA16.采用原子力显微镜(AFM)、旋转流变仪(Rheometer)、傅立叶变换红外光谱仪(FTIR)、倒置荧光显微镜等技术对多肽RAGA16的自组装结构、肽链的二级结构、流变学性能以及细胞相容性等进行研究.结果表明,蚕丝蛋白多肽序列引入后,多肽RAGA16具有自组装特性,能够自组装形成致密的纳米级三维网络结构,所形成的水凝胶力学性能明显提高,通过分析得知这可能是由于多肽二级结构中Silk Ⅰ结构成分比例增加所致.荧光染色显示,绝大多数接种于多肽水凝胶中的小鼠前成骨细胞MC3T3-E1能存活,且在不同的三维平面上生长增殖.综上,利用蚕丝蛋白特征序列对RADA16-Ⅰ进行仿生改性后,对拓展多肽材料在生物医学领域的应用具有重要意义.     

Petrogenesis of Aoyougou high-silica adakite in the North Qilian orogen, NW China: Evidence for decompression melting of oceanic slab

A trondhjemitic body occurs in the Aoyougou area,the western part of the North Qilian orogen.It is geochemically characterized by high SiO 2,Na 2 O (high Na/K),elevated Sr/Y and (La/Yb) N,positive Sr anomaly,relatively enriched large ion lithophile elements (LILEs) and light rare earth elements (LREEs),and depleted Nb,Ta,Ti,resembling the high-silica adakite.Zircon U-Pb SHRIMP dating yields a weighted mean age of 438±3 Ma.This age is significantly younger than eclogitization ages of 460-490 Ma in the North Qilian orogen,suggesting that formation of the adakite postdates the subduction of oceanic crust in association with closure of the ancient Qilian Ocean.Whole-rock Sr and Nd isotopic analyses give initial ratios of I Sr =0.7044 0.7047 and Nd (t)=3.0 4.1,indicating that they are derived from partial melting of the juvenile oceanic crust.In view of the tectonic evolution of the North Qilian orogen,the high-silica adakite was probably derived from decompression melting of the exhumed eclogite at the depth of ～60 km.     

Leptomeningeal metastasis from central nervous system tumors: A study of classification and stage in the spinal canal of 58 patients

Leptomeningeal metastasis (LM) is caused by the spread of malignant tumor cells into the subarachnoid space.However,classification and staging of LM in the spinal canal is rare in the literature.The authors reviewed the records of 58 Chinese patients with LM for clinical features,neuroimaging,and treatments.Gadolinium-enhanced magnetic resonance imaging (MRI) of brain and spinal cord were performed in all patients.Removal of intracranial tumors was performed in all patients and diagnoses were confirmed by histology.The study group consisted of 58 patients,with 29 cases presenting with intraspinal symptoms.Of the 58,8 patients underwent intraspinal tumor removal,8 received radiotherapy alone,9 received chemotherapy alone,and 34 patients received combined radiochemotherapy.We classified LM into 3 types:type L or leptomeninges LM,is subdivided into 2 subtypes (subtype LI and LII (a,b)),type N or nerve root LM is subdivided into 2 subtypes (subtype NI and NII (a,b)),and type M or mixed-type LM.We also divided LM into stages of I-IV according to the symptoms and the volume of the tumor based on spinal axial MRI.Type LI LM often occurs in patients with intracranial and intraspinal tumors found simultaneously.Patients who receive surgery for intracranial tumors may present with type N LM.Surgery is suitable for patients with NI LM and LIIb LM in stages III-IV,presenting with severe spinal symptoms.The prognosis is better for type N LM than type L LM.     

Degradation of the antibiotic sulfamonomethoxine sodium in aqueous solution by photo-Fenton oxidation

In this study, photo-Fenton oxidation was applied to degradation of sulfamonomethoxine sodium (SMMS) in aqueous solution. The operation parameters of pH, temperature, and concentrations of H2O2, Fe2+ and SMMS were investigated. The optimum conditions for the photo-Fenton process were determined as follows: [SMMS]=4.53 mg/L, pH 4.0, [H2O2]=0.49 mmol/L, [Fe2+]= 19.51 μmol/L and T=25°C. Under these conditions 98.5% of the SMMS degraded. The kinetics were also studied, and degradation of SMMS by the photo-Fenton process could be described by first-order kinetics. The apparent activation energy was calculated as 23.95 kJ/mol. Mineralization of the process was investigated by measuring the chemical oxygen demand (COD), and the COD decreased by 99% after 120 min. This process could be used as a pretreatment method for wastewater containing sulfamonomethoxine sodium.     

Web服务组合中异构数据的解决方案

从定义的接口功能上看,用于Web服务组合的Web服务之间的异构主要表现为数据定义抽象层次的异构、数据实体定义的异构及数据定义领域的异构.针对Web服务组合中存在的这些问题,提出了基于语义本体的异构数据转换模型,详细阐述了实现异构数据转换的关键技术,给出了基于语义本体的异构数据转换的实现过程.     

新型垂直流人工湿地组合工艺处理剩余污泥实验研究

剩余污泥是污水处理过程产生的主要副产品和有机废物,它的处理与处置是污水处理的重要组成部分.通过6个月的实验室模拟,研究了一种新型垂直流人工湿地组合工艺对剩余污泥的脱水和渗滤液的净化效果.结果表明,随着停留时间的增长污泥含水率和挥发性固体呈下降趋势,脱水后污泥含水率为40%,挥发性固体去除率达48.2%.在实验期间,共有392 L新鲜剩余污泥得到处理,获得10.3 L干污泥,污泥体积减小97.4%.湿地床表面污泥以平均每月0.87 cm的速度增厚,到试验结束时为5.23 cm深.组合系统以20.0 L(/m2.d)的污泥负荷间歇进泥方式运行,其污泥渗滤液的TN,TP和COD的平均去除率可分别达75.2%,97.3%和78.4%.结果说明该垂直流人工湿地组合系统可以作为传统污泥处置的一个替代方法,是一种建造简单、维护成本低的生态处理方法.     

MIMO干扰信道下基于功率分配的干扰抑制算法

为了抑制MIMO干扰信道下的多小区干扰,采用子空间干扰抑制算法和功率分配相结合的干扰抑制方案,该方案充分利用系统总功率,将多小区干扰尽可能地重叠,以提高系统的性能.理论分析及仿真结果表明,与传统干扰抑制方案相比,该方案仅牺牲极微小的系统容量,却明显地降低了系统的干扰功率.