Selective protection of cells against X-irradiation. Isoproterenol protects only those cells that possesβ-adrenoreceptors

Summary In mixed culture of Chinese hamster fibroblatst, clone 431, and transformed murine L fibroblasts, clone B-82, isoproterenol was found to protect only 431 cells against ionizing radiation. It was shown that 431 cells, in contrast to B-82 cells, possess-adrenoreceptors, and the radioprotective effect of isoproterenol can be realized only if this agent interacts with-adrenoreceptors coupled with the cAMP system. Since malignization often causes the disappearance of-adrenergic and other hormone receptors, the combined culturing and irradiation of the cells studied can be regarded as a model of the growth of malignant cells (B-82) among normal tissue cells (431 cells) under conditions of radiation therapy. A possibility of selective protection against radiation damage of normal tissue cells, with retention of the former radiosensitivity of tumor cells, is discussed.     

Structure of the human CLC-7/Ostm1 complex reveals a novel state

CLC-7 functions as a Cl?/H+ exchanger in lysosomes. Defects in CLC-7 and its β-subunit, Ostm1, result in osteopetrosis and neurodegeneration. Here, we present the cryogenic electron microscopy (cryo-EM) structure of the human CLC-7/Ostm1 complex (HsCLC-7/Ostm1) at a resolution of 3.6 ?. Our structure reveals a new state of the CLC-7/Ostm1 heterotetramer, in which the cytoplasmic domain of CLC-7 is absent, likely due to high flexibility. The disordered cytoplasmic domain is probably not able to restrain CLC-7 subunits and thus allow their relative movements. The movements result in an approximately half smaller interface between the CLC-7 transmembrane domains than that in a previously reported CLC-7/Ostm1 structure with a well-folded cytoplasmic domain. Key interactions involving multiple osteopetrosis-related residues are affected by the interface change.     

Metabolism of 3β-hydroxycholest-5-en-26-oic acid in hamsters

Summary Metabolism of 26-hydroxycholesterol to 3-hydroxychol-5-en-24-oic acid and other C24-bile acids has been expected to occur by way of 3-hydroxycholest-5-en-26-oic acid in studies in vitro. 3-Hydroxycholest-5-en-26-oic acid was infused intravenously into bile fistula hamsters and the following C24-bile acids were identified: 3-hydroxychol-5-en-24-oic acid, lithocholic acid, chenodeoxycholic acid, and a small amount of cholic acid.     

〔23，12，7〕Golay码的改进译码算法

ＭａｒｉｏＢｌａｕｍ和ＪｅｈｏｓｈｕａＢｒｕｃｋ提出了一种基于［２３,１２,７］Ｇｏｌａｙ码校验矩阵＂设计＂特性的译码算法,和其它的Ｇｏｌａｙ码译码算法相比,这种译码算法的复杂度最小,但它不便于用集成器件实现和不便于完全集成化,作者对该算法进行了改进,使其易于集成实现;同时使［２３,１２,７］Ｇｏｌａｙ码译码算法进一步简化．对其复杂度分析证明,当误码率≤１０％时,作者所设计的译码算法优于其它译码算法。     

Spontaneous transformation of C60Br24 to C60 in solvents

It was found that C₆₀Br₂₄ transforms to C₆₀ spontaneously in some solvents. The intermediate, C₆₀Br₈, can be separated in some cases. When the bromine trap, phenol, was added,p-bromophenol and other brominated product were obtained and identified. The influences of time, the kind of solvent, etc were investigated. Possible mechanism was suggested. Supported by the National Natural Science Foundation of China Liu Ying: born in 1969, Ph. D     

再生丝心蛋白和羧甲基纤维素复合膜的特性及其在有机相葡萄糖生物传感器中的应用

用再生丝心蛋白和羧甲基纤维素构成的复合膜作为固定葡萄糖氧化酶的基质,并用红外光谱测试了该复合膜的结构,用扫描电子显微镜观察了其形态．用上述复合膜材料固定葡萄糖氧化酶和羧酸二茂铁（或７,７,８,８－四氰代二甲基苯醌,ＴＣＮＱ）制成的葡萄糖生物传感器具有较好的灵敏度与稳定性     

7,8-二甲基-3,6-二苯基-5-氧-8-氮螺[2.6]壬-4,9-二酮的合成及其晶体结构

利用手性源（2R,3S）－3,4-二甲基-2-苯基-1,4-氧氮杂-5,7-二酮（1）合成了具有光学活性的7,8-二甲基-3,6-二苯基-5-氧-8-氮螺[2．6]壬-4,9-二酮（3）．测定了化合物（3）的晶体结构,并讨论了在环加成反应中的不对称诱导作用的机理．     

薄层色谱法测定戊二酰基-7-氨基头孢烷酸酰化酶的活力

用薄板层析分离ＧＬ＿７＿ＡＣＡ酰化酶反应的产物和底物,然后用薄层扫描仪进行扫描定量,经过与ＧＬ＿７＿ＡＣＡ和７＿ＡＣＡ标准品的薄层扫描相比较,得出酶反应液中的７＿ＡＣＡ浓度,从而计算出ＧＬ＿７＿ＡＣＡ酰化酶的活力     

LaCeCuMn/γ-Al2O3纳米稀土催化剂的制备及性能研究

以纳米纤维状γ-Al₂O₃为载体，采用工艺路线简单的浸渍法制备了La_xCe_1-xCuMn纳米稀土催化剂，并应用微反活性评价装置测试了对CO和C₃H₈的氧化活性。利用XRD，TEM，BET等手段，分析了产品的结构和粒子形貌。实验结果表明，催化剂活性组分在载体上分散比较均匀，平均粒径在15～20nm之间，为纳米级催化剂。La物质的量为0.4mol、活性组分质量分数为15.04%时，制得了较为纯净的钙钛矿催化剂，CO和 C₃H₈氧化反应中起燃温度分别可以达到161，186℃，且二者的最终转化率均在99%以上。     

大肠杆菌O157:H7基因组研究进展

对大肠杆菌O157：H7基因组的结构、特点等近年来的研究进展进行了综述。