THE STUDIES OF MALIGNANT TRANSFORMATION OF HUMAN EPITHELIAL CELLS INDUCED BY DIETHYL-NITROSAMINE (NDEA) IN VITRO

This is the first report on the diethylnitrosamine-induced malignant transformaton of hu-man epithelial cells derived from fetal kidney. The transformed cells have prolonged life span and aneuploid karyotypes. They also form anchorage independent colonies in soft agar. With additional one or two NDEA treatments, those cells could elicit poorly differontiated carcinomas in immunosuppressed new-born rats. This experiment indicates that the human fetal kidney cells seem to be a good material for studying the mechanisms of carcinogenesis of human epithelial cell.     

MALIGNANT TRANSFORMATION OF BABY HAMSTER LUNG FIBROBLASTS INDUCED IN VITRO BY A NEW NITROSAMINE COMPOUND

A new nitrosamine compound, N-1-methylacetonyl-N-3-methylbutyl-nitrosamine (MAMB-NA), isolated from corn bread inoculated with moulds commonly occurring in Linxian County,a high incidence area for esophageal cancer in North China was tested for its potentialcarcinogenicity in vitro. Baby hamster lung fibroblasts (BHL) were treated with MAMBNAin tissue culture medium containing liver microsome preparation of Aroclor 1254 treatedrat. Cell transformation was assessed by morphological changes, loss of density-dependentinhibition and unlimited growth in vitro, chromosome changes, colony formation on softagar, growth at low serum concentration, Con A agglutinability and tumor formation afterheterotransplantation into immunosuppressed newborne rats. Like the known carcinogensN-methyl-N'-nitro-N-nitroso-guanidine and diethylnitrosamine, MAMBNA was able to causemalignant transformation of cells cultured in vitro.     

食管癌癌旁上皮细胞的G显带染色体分析——出现某种规律性染色体改变

本实验首次用G显带的方法分析了食管癌癌旁上皮原代培养细胞的染色体,在7例标本中至少有二例出现规律性的染色体改变,其标记染色体与食管癌细胞系EC8501中出现的标记染色体十分相似,证明食管癌癌旁粘膜上皮细胞的染色体已经在数目和结构上发生了明显的畸变,本工作开辟了探明食管癌癌变早期的染色体重排的途径。     

痕量硒的流动注射,在线还原,氢化物发生原子吸收测定法

本实验采用了流动注射分析（ＦＩＡ）技术，使试样溶液中以不同氧化态存在的待测元素，在线还原为易生成氢化物的形式，用氢化物发生原子吸收光谱法直接测定硒的含量。在加热的管路中混合还原抑制剂不仅使待测元素在线还原为易生成氢化物的形式，又可抑制基体元素的干扰。生成的氢化物经我们自制的带雾化器的气液分离器分离后，进入原子化器。用本法分析地质标样的结果与推荐值能很好吻合，其检出限为１．０８×１０－１０ｇ／ｍＬ，相对标准偏差为１．４４％。     

C-myc反义RNA特异性诱发人食管癌细胞程序性死亡

本文报道以含有neo基因序列的逆转录病毒为载体,按1:1感染强度(细胞:病毒颗粒)向人食管癌细胞系EC8712中导入可持续产生互补于c-myc基因第二外显子及其两侧序列共1.53kb片段的反义RNA基因,得到G418抗性细胞。后者表型发生明显的改变,细胞生长抑制率为86.3％,c-Myc蛋白含量降低80％左右,而胎儿和成人食管上皮原代培养细胞的形态和生长速度没有明显改变。在1:10感染强度下,不经G418筛选,感染后12h行Southern blot(DNA)和Northern blot(RNA)分析,分别发现外源反义c-myc基因完整地整合到癌细胞基因组中并能有效表达,同时使内源性c-myc基因的表达降低了73.6％。病毒感染的瘤细胞在裸鼠体内形成肿瘤的能力明显下降。首次发现,反义c-myc RNA可抑制c-myc高表达的人食管癌细胞生长、诱导分化和程序性细胞死亡,同时,不损害或很少影响myc表达低的正常细胞。     

Effect of misfit strain on the electrocaloric effect of polydomain epitaxial ferroelectric thin films

The effect of misfit strain on the electrocaloric effect in polydomain epitaxial BaTiO 3 thin films at room temperature is investigated using the Ginzburg-Landau-Devonshire thermodynamic theory. Numerical calculations indicate that the misfit strain has a large impact on the ferroelectric polarization states and the electrocaloric effect. Most importantly, the electrocaloric effect in the polydomain ca 1 /ca 2 /ca 1 /ca 2 phase is much larger than that in the monodomain c phase and the other polydomain phases. Consequently, a large electrocaloric effect can be obtained by carefully controlling the misfit strain, which may provide potential applications in refrigeration devices.     

Composition and misfit strain dependence of electrocaloric effect of Pb1-x SrxTiO3 thin films

A Landau-Devonshire thermodynamic theory is employed to investigate the effects of composition and misfit strain on the room-temperature electrocaloric effect of epitaxial Pb1-xSrxTiO3 thin films. The "temperature-misfit strain" phase diagrams with the Sr composition x of 0.1, 0.3, and 0.5 are constructed. The introduction of Sr composition reduces the Curie temperature greatly, and enhances the electrocaloric effect. Moreover, the electrocaloric effect largely depends on the misfit strain. Therefore, the Sr composition and the misfit strain can be controlled to obtain the giant room-temperature electrocaloric effect.     

空中加油最优分配建模与实现

确定最佳空中加油方案,既有一定难度,又有重要的实用价值.本文针对加油机可以多次上天情况,对这一问题展开研究,确定了使主机飞行距离最大的空中加油方案.我们将飞机飞行过程分为出航和返航两个阶段,首先利用数学归纳法得出出航阶段的最佳加油方案;然后对返航过程建立约束方程组,求出返航阶段的最佳加油方案.利用这一模型结果可以对任意多架加油机的情况确定全程最佳加油方案.最后结合出航、返航编队及飞行姿态调整对模型作了一定范围的定量扩展,使本文的研究更具有实用价值.     

A STRATEGY FOR ISOLATING DIFFERENTIATIONINDUCING COMPLEMENTARY DNAs FROM HUMAN ESOPHAGEAL CANCER CELL LINE TREATED WITH RETINOIC ACID

Treatment of the human esophageal cancer cell line EC8712 with retinoic acid (RA) stopped the cell growth significantly and gave rise to terminal differentiation of the cells characterized by increased expression of involucrin gene. Two cDNA libraries were constructed from the parental and RA-treated cells respectively. Repeated subtractive hybridization of single-stranded plasmid DNA prepared from pooled colonies of cDNA library of the parental cells with cDNA probe generated from the RA-treated cells exhausted sequences common to both libraries of the cell. The unhybridized cDNA probe represented, therefore, the genes activated after RA-treatment. By using these enriched cDNAs as probe to screen the cDNA library constructed from the RA-treated cells thirty-nine positive colonies were obtained, of which two were specifically due to RA-induction. One of these two cDNA clones, designated as pRA538, has undergone further analysis and shown differentiation-inducing effect on parental cancer cells. A novel     

体外化学诱发人食管成纤维细胞恶性转化

从一例52岁食管鳞癌患者的食管组织得到的原代成纤维细胞.经用化学致癌物(N-methyl-N’-nitro-N-nitrosoguanidine,MNNG)处理后。诱发了恶性转化.细胞显示恶性细胞的生物学及形态学特性,如失去接触抑制、体外无限制的生长、非整倍体性、ConA凝集性、细胞表面微绒毛形成,在琼脂固体培养基上生长,在免疫抑制的新生小鼠上接种形成肿瘤(低分化纤维肉瘤).