Structure of the catalytic domain of human phosphodiesterase 5 with bound drug molecules

Phosphodiesterases (PDEs) are a superfamily of enzymes that degrade the intracellular second messengers cyclic AMP and cyclic GMP. As essential regulators of cyclic nucleotide signalling with diverse physiological functions, PDEs are drug targets for the treatment of various diseases, including heart failure, depression, asthma, inflammation and erectile dysfunction. Of the 12 PDE gene families, cGMP-specific PDE5 carries out the principal cGMP-hydrolysing activity in human corpus cavernosum tissue. It is well known as the target of sildenafil citrate (Viagra) and other similar drugs for the treatment of erectile dysfunction. Despite the pressing need to develop selective PDE inhibitors as therapeutic drugs, only the cAMP-specific PDE4 structures are currently available. Here we present the three-dimensional structures of the catalytic domain (residues 537-860) of human PDE5 complexed with the three drug molecules sildenafil, tadalafil (Cialis) and vardenafil (Levitra). These structures will provide opportunities to design potent and selective PDE inhibitors with improved pharmacological profiles.     

轴对称膜大变形的一个新的理论模型

本文根据美国佐治亚理工学院陈又亮博士提出的轴对称膜大变形的一个新的理论模型,解出内、外固定环膜的变形问题,计算结果与实验基本吻合。同时用此理论模型又解出了平面圆膜的膨胀问题,得到了与其他学者相同的结果。     

黄海周边河流的稀土元素地球化学及沉积物物源示踪

黄海周边的中韩主要河流悬浮沉积物中稀土元素组成不同, 韩国河流的稀土元素分异强于中国长江、黄河和鸭绿江, 表现为上陆壳标准化模式上明显的轻稀土相对富集. 不同级别的流域内源岩组成差异是形成这些河流稀土元素组成差异的主要因素. 稀土元素分异参数(La/Yb)_UCC和(Gd/Yb)_UCC, 以及稳定的La/Sc和Th/Sc元素比是识别进入黄海的中韩河流沉积物的可靠指标, 可以用于中国边缘海沉积物物源研究和古环境分析.     

Spatial aggregations for spatial based decision making in spatial data warehouses

For spatial based decision making such as choice of best place to construct a new department store, spatial data warehousing system is required more and more previous spatial data warehousing systems; however, provided decision making of non-spatial data on a map and so those cannot support enough spatial based decision making. The spatial aggregations are proposed for spatial based decision making in spatial data warehouses. The meaning of aggregation operators for applying spatial data was modified and new spatial aggregations were defined. These aggregations can support hierarchical concept of spatial measure. Using these aggregations, the spatial analysis classified by non-spatial data is provided. In case study, how to use these aggregations and how to support spatial based decision making are shown.     

近红外光谱技术结合主成分聚类鉴别海面溢油

鉴于目前没有一种方法能独立解决溢油鉴别的所有问题[1],本文提出近红外光谱技术结合主成分聚类分析鉴别溢油种类的方法.通过有机溶剂萃取出自行配制的汽油、柴油和润滑油模拟样品中的溢油后记录其近红外光谱,对5 800～6 200 cm-1区段范围内的近红外谱图经过多元散射校正(MSC),Norris一阶导数平滑预处理处理后求其主成分,并在主成分的基础上引入Ward聚类分析法(离差平方和法)对样品分类.     

Crl：CD（SD）IGS BR大鼠繁育体系的维持与进展

遗传标准化的近交系啮齿类动物体系已有较好的描述,由于生物医学研究的国际化,各国的实验动物供应商应对一般常用的非近交系毒理学动物模型和ＳｐｒａｇｕｅＤａｗｌｅｙ及ＨａｎｏｖｅｒＷｉｓｔａｒ大鼠种系等进行全球标准化,本文描述该类繁育体系,即国际生物医学研究机构采用的Ｃｒｌ：ＣＤ（ＳＤ）ＩＧＳＢＲ和Ｃｒｌ：ＷＩ（ＧＬＸ／ＢＲＬ／Ｈａｍ／ＩＧＳ）ＢＲ大鼠的国际遗传学标准体系（ＩＧＳ）。