8—MOP对体外培养人癌细胞的光敏灭活作用

本文根据MTT只能被活的增殖细胞中线粒体切断形成紫色甲(?)的原理,测定了8—甲氧基补骨脂素(8—MOP)对体外培养人癌细胞系HCT、KB和BEL细胞的光敏灭活作用。结果表明,8—MOP和UVA光照对这几种人癌细胞有肯定的灭活作用,该作用与8—MOP剂量和光照时间以及细胞种类有关;MTT法可以作为光敏剂活性检测的一种快捷方法。     

抑制O~6-甲基鸟嘌呤-DNA甲基转移酶活性与肿瘤细胞对亚硝脲药物敏感性关系的研究

80％以上的肿瘤细胞为O~6-甲基鸟嘌吟-DNA甲基转移酶(O~6-MT)活性较高的Mer~+型,能够修复亚硝脲药物(NU)造成的DNA烷化损伤,对NU不敏感。本实验证明,用0.75,0.50和0.25mmol/L甲基亚硝脲(MNU)分别处理Mer~+型的HeLaS3,SMMC-7721和表现Mer~-型特征的Cc801,均能明显降低细胞中O~6-MT活性,从而显著提高了三种细胞对嘧啶亚硝脲和双氯乙亚硝脲的敏感性,提示降低O~6-MT活性是使用NU对Mer~+型肿瘤进行有效治疗的前提。     

Growth modulation by epidermal growth factor (EGF) in human colonic carcinoma cells: constitutive expression of the human EGF gene

The functional role of epidermal growth factor (EGF) in epithelium-derived human colonic carcinoma cells was investigated by transfection with plasmid pUCDS3, which contained synthetic human EGF encoding sequences, into two human colonic carcinoma cell types with dissimilar phenotypic properties: the moderately differentiated and growth factor-responsive Moser and the highly metastatic KM12SM cells. The Moser cells exhibited a proliferative response to treatment with exogenous EGF, while the KM12SM cells did not. The constitutive expression of the human EGF gene in these colonic carcinoma cell types resulted in elevated expression of EGF mRNA, with concurrent production and secretion of a large amount of EGF, and downmodulation of transforming growth factor-alpha (TGF-alpha) secretion. Growth stimulation and down-modulation of both high and low affinity EGF receptors were observed in the EGF-transfected Moser clones. Results of experiments using anti-EGF and anti-EGF-receptor antibody to block the proliferation of EGF-transfected Moser clones suggested that autocrine stimulatory mechanisms involving both EGF and TGF-alpha were operative in these cells. By comparison, a growth-inhibitory effect, with no apparent EGF receptor modulation, was observed in the EGF-transfected KM12SM clones. Both the parental and EGF-transfected KM12SM clones possessed fewer EGF receptors than the Moser cells, and anti-EGF or anti-EGF-receptor antibody did not affect the cells' growth properties. These results suggested that the mechanisms of growth inhibition in the EGF-transfected KM12SM clones were non-autocrine or intracellular in nature. Thus, constitutive expression of the human EGF gene in two phenotypically different, epithelium-derived human colonic carcinoma cells resulted in divergent altered growth characteristics.     

Alkylation of nucleic acids by DNA-targeted 4-anilinoquinolinium aniline mustards: kinetic studies

The rate of constant for hydrolysis of a series of 4-substituted aniline mustards Ar-X-pC6H4-N(CH2CH2Cl)2, where Ar is 4-anilinoquinolinium and X = O, CH2, CONH and CO, have been measured in water and 0.02 M imidazole buffer at 37 degrees C and in 50% aqueous acetone at 66 degrees C. The equilibrium binding constants of the compounds and their hydrolysis products to nucleic acids of differing base composition have been determined at varying ionic strengths, and the results are consistent with the compounds binding as expected in the DNA minor groove. The alkylating reactivity of the mustards towards these nucleic acids has been measured in water at 37 degrees C and in 0.01 M HEPES buffer over a range of temperatures from 25 degrees C to 60 degrees C. Evaluation of the thermodynamic parameters for these kinetic and equilibrium studies suggests that the interaction with nucleic acids is via an internal SN2 mechanism involving an aziridinium ion.     

Poor efficacy of albendazole for the treatment of human taeniasis

In order to evaluate the efficacy of albendazole for the treatment of taeniasis, regimens of 400 mg x 1 day, 800 mg x 2 days, 800 mg x 3 days, 1200 mg x 2 days, and 1200 mg x 3 days were compared. Of 66 cases treated and investigated 7-14 days after treatment, 52 were still expelling proglottids. Three months posttreatment, these cases were re-treated with atabrine at 1.2 g per case for males and 1.0 g per case for females. Fifty-seven patients expelled worms or parts of tapeworms. The nine negatives may represent the number cured by the treatment with albendazole. The cure rates with albendazole for various regimens were up to 50% for 800 mg x 3 days, 1200 mg x 2 days or 1200 mg x 3 days, 14.3% for 800 mg x 2 days, and 0% for 400 mg x 1 day or 800 mg x 1 day. This study shows that albendazole is not very effective in the treatment for taeniasis.     

ph1b基因在Aegilops有益基因直接遗传转移中利用的可能性

第一次用中国春和中国春ph1b突变体对(中国春phlb突变体×Ae.uariabilis)F_1和(中国春ph1b突变体×Ae.turcomenica)F_1回交获得了成功,并通过连续回交,把Ae.turcomenica的抗白粉基因转移到了普通小麦中。证实了利用ph1b基因从山羊草属的一些种“直接遗传转移”有益基因到普通小麦中的可能性。     

农药的轭合与结合态残留

随着科技水平的不断提高,人们对农药残留影响生态环境的认识不断在更新和完善。农药的轭合与结合残留是在标记农药的出现和高精度分析仪器和技术得到应用后被发现和认识的。国外在这方面的研究开展得较早,工作也较     

日本落叶松人工林针叶中矿质营养元素的季节吸收特点及其相互关系

本文测定了日本落叶松人工林针叶中N、P、K、Ca、Mg、Cu、Zn、Fe、Mn9种矿质营养元素含量并研究了生长期内元素含量的变化规律。结果表明,在生长期内各元素含量随季节变化可用修正指数曲钱描述;探讨了落叶松针叶中常量元素与某些土壤化学因子之间的关系。土壤有机质仅与土壤全量氮、水解氮表现了显著的线性相关,与落叶松针叶中的氮没有直接的线性相关。土壤中钙镁的含量则表现出明显的对针叶中磷、钾的含量的制约关系。在日本落叶松针叶中的氮、磷、钾3个元素之间,氮、磷的比值与钾的含量有显著的线性负相关,而磷与钾之间则表现为显著的线性正相关关系。     

Characterization of the Bacillus subtilis sporulation gene spoVK.

The sporulation gene spoVK of Bacillus subtilis was cloned by use of the insertional mutation spoVK::Tn917 omega HU8. The spoVK gene was shown to be the site of an incorrectly mapped mutation called spoVJ517. Thus, a separate spoVJ gene as defined by the 517 mutation does not exist and is instead identical with spoVK.     

Up-regulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) receptors in murine peritoneal exudate macrophages by both GM-CSF and IL-3.

Murine peritoneal exudate macrophages (PEM) display multiple CSF receptors. In this study, the expression of granulocyte-macrophage (GM)-CSF receptors in PEM was studied. PEM displayed over 5000 single type, high affinity GM-CSF receptors/cell with a Kd = 38 to 42 pM and an apparent molecular mass of 86,000 Da. Treatment of PEM with low, but not high, concentrations of recombinant murine (rMu) GM-CSF continuously for 24 h resulted in a marked up-regulation of GM-CSF receptors in PEM. A similar up-regulation of GM-CSF receptors also was detected in PEM cultures treated with rMuIL-3 (1-100 ng/ml) for 24 h or longer, regardless the doses of rMuIL-3 added in this case. Scatchard analysis of equilibrium binding showed that the enhanced binding activities in both cases were due to an increase in total number of GM-CSF receptors rather than changes in receptor affinity. Contrariwise, treatment with recombinant human macrophage-CSF (greater than 100-1000 ng/ml) partially inhibited the expression of GM-CSF receptors in PEM. Removal of rMuGM-CSF from culture medium 24 h after treatment led to a further up-regulation of GM-CSF receptors over a 4 to 24-h period, depending on the doses of initial treatment. On the other hand, removal of rMuIL-3 from culture medium after prolonged treatment did not result in further increase in GM-CSF receptors. The protein synthesis inhibitor cycloheximide abrogated GM-CSF receptor up-regulation induced by both rMuIL-3 and rMuGM-CSF, whereas actinomycin D inhibited only the second (8-24 h) phase of GM-CSF receptor up-regulation induced by exposure to high concentrations rMuGM-CSF (10 ng/ml). These findings suggest that rMuGM-CSF and rMuIL-3 up-regulate GM-CSF receptors in PEM in part through similar or identical metabolic pathways and provide further evidence of a close linkage between IL-3 and GM-CSF receptors.