Induction of membrane ruffling and fluid-phase pinocytosis in quiescent fibroblasts by ras proteins

Expression of the ras oncogene is thought to be one of the contributing events in the initiation of certain types of human cancer. To determine the cellular activities that are directly triggered by ras proteins, the early consequences of microinjection of the human H-ras proteins into quiescent rat embryo fibroblasts were investigated. Within 30 minutes to 1 hour after injection, cells show a marked increase in surface ruffles and fluid-phase pinocytosis. The rapid enhancement of membrane ruffling and pinocytosis is induced by both the proto-oncogenic and the oncogenic forms of the H-ras protein. The effects produced by the oncogenic protein persist for more than 15 hours after injection, whereas the effects of the proto-oncogenic protein are short-lived, being restricted to a 3-hour interval after injection. The stimulatory effect of the ras oncogene protein on ruffling and pinocytosis is dependent on the amount of injected protein and is accompanied by an apparent stimulation of phospholipase A2 activity. These rapid changes in cell membrane activities induced by ras proteins may represent primary events in the mechanism of action of ras proteins.     

Nonsteroidal anti-inflammatory drugs can lower amyloidogenic Abeta42 by inhibiting Rho

A subset of nonsteroidal anti-inflammatory drugs (NSAIDs) has been shown to preferentially reduce the secretion of the highly amyloidogenic, 42-residue amyloid-beta peptide Abeta42. We found that Rho and its effector, Rho-associated kinase, preferentially regulated the amount of Abeta42 produced in vitro and that only those NSAIDs effective as Rho inhibitors lowered Abeta42. Administration of Y-27632, a selective Rock inhibitor, also preferentially lowered brain levels of Abeta42 in a transgenic mouse model of Alzheimer's disease. Thus, the Rho-Rock pathway may regulate amyloid precursor protein processing, and a subset of NSAIDs can reduce Abeta42 through inhibition of Rho activity.     

牧马豆生物碱抑菌抗炎作用研究

将牧马豆生物碱配制成不同的质量浓度,通过试管法测定其最小抑菌质量浓度.结果表明,牧马豆生物碱对大肠埃希氏菌、巴氏杆菌、链球菌、金黄色葡萄球菌均有一定的抑制作用.以小鼠为实验动物,选用不同质量浓度的牧马豆生物碱注射剂对二甲苯所致小鼠耳壳肿胀均有显著抑制作用.     

5种非甾体类抗炎药对小鼠的肝损伤作用

【目的】探讨阿司匹林(ASA)、保泰松(PTZ)、吲哚美辛(IDM)、吡罗昔康(PRX)、氟比洛芬(FBP)等5种非甾体类抗炎药(NSAIDs)对小鼠肝脏的损伤作用,为研究NSAIDs对肝损伤的作用机制提供参考。【方法】将70只昆明小白鼠,随机分为正常对照组(NC)、对乙酰氨基酚阳性对照组(APAP)、ASA组、PTZ组、IDM组、PRX组和FBP组,每组10只,NC组灌胃质量分数0.5%CMC-Na, APAP组灌胃70 mg/kg APAP,ASA组、PTZ组、IDM组、PRX组和FBP组分别灌胃50,54,2.4,2.6和7.5 mg/kg剂量的相应NSAIDs,每天2次,连续3 d;末次给药12 h后,眼丛静脉采血分离血清并采集肝脏样品,检测血清谷丙转氨酶(ALT)和谷草转氨酶(AST)水平及肝脏氧化指标(丙二醛(MDA)、谷胱甘肽(GSH)含量及超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)的活性);苏木精-伊红染色进行肝组织病理组织形态学观察,评价肝脏损伤程度;体外提取正常小鼠肝线粒体,将5种NSAIDS梯度稀释,使ASA、PTZ和PRX配置浓度均为64,128,256和512μmol/L,IDM和FBP配制浓度为32,64,128和256μmol/L,然后与线粒体共孵育并检测CYP2E1的活性,检测5种NSAIDs对肝脏CYP2E1活性的影响,进一步探究NSAIDs诱导肝损伤的潜在作用机制。【结果】除PRX外,其余4种NSAIDs均可不同程度使小鼠AST、ALT和MDA水平升高,降低抗氧化防御系统SOD、GSH和GSH-Px的水平;肝脏病理学观察发现,PRX对肝组织几乎无损伤作用,ASA的急性肝损伤作用较弱,IDM、FBP和PTZ对小鼠肝脏损伤作用较强,主要表现为边缘圆钝,肝体发黄;镜下观察为肝细胞颗粒变性,并伴有肝细胞坏死,小叶间结构不清晰,沿中央静脉和肝索分布有一定数量的炎性细胞。体内外试验均表明,IDM、FBP和PTZ能够诱导CYP2E1,而PRX和ASA对CYP2E1几乎无显著诱导作用。【结论】5种NSAIDs类药物中,PRX对肝组织无损伤作用,ASA对小鼠肝脏损伤作用较小,IDM、FBP和PTZ可能通过诱导CYP2E1导致线粒体功能障碍而引发肝脏损伤。     

Induction of cellular senescence in immortalized cells by human chromosome 1

The control of cellular senescence by specific human chromosomes was examined in interspecies cell hybrids between diploid human fibroblasts and an immortal, Syrian hamster cell line. Most such hybrids exhibited a limited life span comparable to that of the human fibroblasts, indicating that cellular senescence is dominant in these hybrids. Karyotypic analyses of the hybrid clones that did not senesce revealed that all these clones had lost both copies of human chromosome 1, whereas all other human chromosomes were observed in at least some of the immortal hybrids. The application of selective pressure for retention of human chromosome 1 to the cell hybrids resulted in an increased percentage of hybrids that senesced. Further, the introduction of a single copy of human chromosome 1 to the hamster cells by microcell fusion caused typical signs of cellular senescence. Transfer of chromosome 11 had no effect on the growth of the cells. These findings indicate that human chromosome 1 may participate in the control of cellular senescence and further support a genetic basis for cellular senescence.     

Morphological transformation in vitro of human fibroblasts by Epstein-Barr virus: preliminary observations

Human embryo fibroblasts have undergone morphological transformation in vitro after infection by Epstein-Barr virus. The fibroblasts were maintained in suspension during exposure to the virus, and further treatment with inactivated Sendai virus increased the transformation rate. The transformed cells were large and polygonal and grew in discrete, heaped up, foci.     

Induction of the c-fos oncogene by thyrotropic hormone in rat thyroid cells in culture

Rat thyroid cells in culture, rendered quiescent by hormone deprivation, can be stimulated to undergo DNA synthesis in the absence of serum by the addition of purified thyrotropin. The primary effect in response to thyrotropin action in thyroid cells is the induction of the c-fos oncogene, followed by c-myc expression. This suggests that thyrotropin acts as a competence growth factor.     

Mutant enzymatic and cytological phenotypes in cultured human fibroblasts

Fibroblasts were cultured from the cells of two children who shared some characteristics of Hurler syndrome, but they did not show corneal clouding and excessive excretion of mucopolysaccharides. The fibroblasts differ from those of controls and of patients with typical Hurler syndrome or other mucopolysaccharidoses in that they have abundant cytoplasmic inclusions, striking diminutions in beta-glucuronidase, and elevations in acid phosphatase.     

Genotoxicity of formaldehyde in cultured human bronchial fibroblasts

Formaldehyde, a common environmental pollutant, inhibits repair of O6-methylguanine and potentiates the mutagenicity of an alkylating agent, N-methyl-N-nitrosourea, in normal human fibroblasts. Because formaldehyde alone also causes mutations in human cells, the compound may cause genotoxicity by a dual mechanism of directly damaging DNA and inhibiting repair of mutagenic and carcinogenic DNA lesions caused by other chemical and physical carcinogens.     

Induction of hemoglobin accumulation in human K562 cells by hemin is reversible

Twenty micromolar hemin causes no change in the rate of division of K562 cells but results in accumulation of 11 to 14 picograms of embryonic and fetal hemoglobins per cell. This effect is reversible, and hemoglobin induction in response to hemin, and loss of hemoglobin upon removal of hemin, can be cyclically repeated. The cells can be indefinitely subcultured in the presence of the inducer. Thus, the control of hemoglobin levels in K562 cells does not depend on irreversible differentiation.     

山苍子油抗炎抗癌活性及保鲜效果研究

以山苍子果实精油为材料,采用小鼠巨噬细胞Raw264.7和小鼠肝癌细胞Hepa 1c1c7为模型,以一氧化氮抑制率为抗炎指标、醌还原酶活性为抗癌指标研究山苍子油及其硅胶柱层析分离产物的抗炎抗癌活性,并将山苍子油与Vc、VE制成复合型保鲜剂涂膜到冷却猪肉表面进行肉类保鲜试验.结果表明,山苍子果实精油具有一定的抗炎抗癌活性,其一氧化氮抑制率≥50％的浓度为31.25～62.50 μg/mL,诱导醌还原酶活性倍增的浓度为15.63～31.25μg/mL.3个层析物中即包括精油A、B、C,只有精油B同时具有抗炎抗癌活性,其浓度分别为25.00～50.00 μg/mL与2.50～5.00 μg/mL;而精油C仅表现抗癌活性,其浓度为5.00～10.00 μg/mL;精油A在该浓度范围内未表现抗炎抗癌活性.同时,山苍子油对冷却猪肉具有较好的保鲜效果,复合保鲜剂最佳配比为山苍子油0.25％、VC0.20％、VE0.25％.上述研究将为山苍子油的开发应用提供理论依据.     

Diploid azaguanine-resistant mutants of cultured human fibroblasts

Two azaguanine-resistant clones of cultured, human fibroblasts were isolated from unrelated strains of karyotypically normal, male cells. The most resistant mutant has little hypoxanthine-guanine phosphoribosyltransferase activity, is virtually unable to incorporate hypoxanthine (a normal substrate of the enzyme), and resembles fibroblasts cultured from boys with the Lesch-Nyhan syndrome. The less resistant mutant has about one-third as much enzyme activity as its parent strain and is less able to utilize hypoxanthine. Both mutants are morphologically and karyotypically normal. These mutations may have occurred at the X-chromosomal, hypoxanthine-guanine phosphoribosyltransferase locus and may provide a realistic experimental model for studying mutation in human genetic material.     

湿地植物根系分泌物中有机酸对NSAIDs胁迫的响应

以人工湿地典型植物芦苇（Phragmites australis）为研究对象,探索芦苇根系分泌物中有机酸对非甾体类消炎药（NSAIDs）混合物（双氯芬酸、布洛芬、吲哚美辛、酮洛芬、萘普生）长期胁迫的响应。首先,优化测定有机酸的高效液相色谱（HPLC）法;然后,构建水培和人工湿地两种体系,于NSAIDs胁迫下（地表水浓度...     

茉莉酸对棉花单宁含量和抗虫相关酶活性的诱导效应

以植物生长调节物茉莉酸(Jasmonic acid,JA)为诱导子,以常规棉为研究对象,探讨了外源茉莉酸对棉花幼苗单宁和蛋白酶抑制素以及其它抗虫相关酶活性诱导的浓度依赖性和持久性,讨论了棉花抗虫相关物质的抗虫效果.结果表明,0.01、0.1和1.0 mmol/L茉莉酸都能在2周内诱导棉花单宁和胰蛋白酶抑制素(Proteinase inhibitors,PIs)含量增加,诱导多酚氧化酶(Polyphenol oxidase,PPO)、苯丙氨酸解氨酶(Phenylalanine ammonia-lyase,PAL)、过氧化物酶(Peroxidase,POD)和过氧化氢酶(Catalase,CAT)活性升高.对3种浓度茉莉酸的诱导效应进行分析表明,0.1 mmol/L茉莉酸对于诱导PIs、PPO、POD和CAT最有效,0.1和1.0 mmol/L茉莉酸对于诱导棉花单宁和苯丙氨酸解氨酶等效,二者的诱导效应均高于0.01 mmol/L.对茉莉酸诱导抗性的持久性进行分析表明,最佳诱导效应发生的时间各不相同:POD活性在JA处理后第1天最高,随后呈下降趋势,PIs和单宁含量分别在JA处理后第7天和第14天达最大值;JA处理后第1天和第7天的PPO活性无明显差异,但明显高于第14天;JA处理后第7天和第14天的PAL活性无明显差异,但明显高于第1天;JA处理后第1、7和14天棉花叶片的CAT活性均无明显差异.以上结果表明,茉莉酸可通过增加棉叶单宁和PIs含量、提高棉叶PAL、PPO、POD和CAT活性等增强棉花幼苗的抗虫性.     

人α-乳白蛋白质基因的克隆及其在奶山羊胎儿成纤维细胞中的表达

采用PCR方法从人类基因组DNA中扩增hα-LA基因,将扩增产物克隆到pMD19-T载体,并进行测序验证。通过双酶切法将测序正确的hα-LA亚克隆至真核表达载体pCEP4,构建真核表达载体pCLA并进行酶切鉴定。用脂质体法将pCLA转染至奶山羊胎儿成纤维细胞中,用RT-PCR法检测细胞中hα-LA基因mRNA的表达,用Western-blotting法检测培养上清液中hα-LA蛋白质的表达。结果显示:克隆的hα-LA基因序列完全正确,pCLA酶切鉴定正确,RT-PCR检测到转染细胞中hα-LA基因mRNA的表达,Western-blotting检测到转染细胞培养上清液中hα-LA蛋白质。表明所克隆的hα-LA基因组DNA能够在奶山羊胎儿成纤维细胞中正确转录和翻译。