共查询到19条相似文献,搜索用时 78 毫秒
1.
通过研究饮茶对香烟中特异性亚硝胺-NNK诱发小鼠肺癌基因表达的影响,对饮茶可拮抗香烟致癌作用的结果做进一步验证,并对其作用机理进行探讨。所使用方法为国内外尚属新的技术,即非同位素标记探针测定基因表达。其结果表明阳性小鼠给NNK4周后,c-myc和c-raf基因表达水平明显增高,而小鼠若同时饮绿茶则可抑制这种增高,抑制率达50%和20%,到第8周时阳性对照组的c-myc和c-raf基因水平恢复正常。与此相对应,c-H-ras基因在第8周时表达增高,约为阴性组3倍,饮茶对此同样有抑制作用,抑制率为50%。在第2、4和8周均未见阳性对照组vsis基因表达水平的改变。 相似文献
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茶对促癌物(TPA)诱发小鼠皮肤癌基因表达的影响 总被引:7,自引:0,他引:7
通过研究在小鼠皮肤上涂抹儿茶素EGCG对促癌物(TPA)诱发小鼠皮肤组织某些癌症发生有重要关系的基因(c-myc,ODC、蛋白激酶C即PKC基因)表达水平的影响,对茶叶抗皮肤癌的机制做了较深入的探讨。其结果表明阳性小鼠皮肤涂10nmolTPA4h后,上皮组织中ODC基因表达水平比阴性组高出4.5倍,而EGCG对其有明显的抑制作用,1μmol和5μmolEGCG剂量组的抑制率分别为16%和56%,有一定的剂量-反应关系。C-myc与pKC基因表达水平在阳性组也有明显的升高,分别为5.0和1.9倍,EGCG同样具有抑制作用,5μmol的抑制率分别为24%和21%。 相似文献
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接触苯工人白细胞癌基因激活的研究 总被引:5,自引:1,他引:4
应用PCR-Blot和Dot-Blot技术检测了103名接触苯工人和70名对照组工人外周血白细胞c-Ki-ras2基因和c-myc基因。结果表明,103名接苯者中有4例其外周血白细胞检出c-Ki-ras2基因12位点G→T突变,其接苯工龄在6~10年,而70名对照者未检出该突变;c-Ki-ras2基因12位点(G→A突变在两组工人中均未检出阳性;c-myc基因亦未在两组工人中检出扩增现象。结果提示,c-Ki-ras2基因12位点G→T突变与慢性接触苯有关,有可能是苯白血病发生的分子机理。 相似文献
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本文对由致癌物苯并芘诱发的人肺癌建立的细胞系(BT)进行了染色体分析及myc,Rb和p53基因研究。发现许多异常染色体,以3号,5号,11号,13号,17号染色体改变较多,对定位于这些染色体上的Ha-ras,raf-1,p53,Rb和c-myc的表达、扩增及重排情况进行了分析,发现c-myc,p53,Rb三个基因发生了改变,说明染色体异常导致的基因改变与苯并芘诱发人肺癌的发生机制可能密切相关。 相似文献
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用免疫组化LSAB方法检测5例正常卵巢组织和35例卵巢肿瘤组织中的C-myc(原癌基因)和p53(抑癌基因)蛋白的表达水平。结果从良性卵巢腺瘤、交界性到恶性卵巢囊腺癌,C-myc和p53阳性表达呈增高趋势。其阳性表达率与卵巢肿瘤的细胞增殖状态、肿瘤分化及临床分期有关。检测卵巢肿瘤中C-myc及p53基因表达可了解卵巢囊腺癌的发生、发展,找出原癌基因及抑癌基因表达与卵巢瘤生物学行为间的关系。 相似文献
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本文观察了非选择性阳离子通道阻断剂链霉素(在脊椎动物心肌阻断牵张激活的钠离子跨膜内流)对缺氧大鼠右心室肥大和缺氧大鼠心肌中c─myc基因表达的影响。结果如下:(1)急性缺氧时,右心室收缩压明显增高,慢性间断性缺氧进一步增高右心室收缩压并明显增高右心室重量指数。(2)链霉素对急性缺氧性肺动脉增压反应无影响,但可明显降低慢性缺氧大鼠右心室收缩压和右心室重量指数。(3)缺氧引起右室心肌迅速一过性的c-myc基因表达增强,链霉素可降低c-myc表达水平。提示Na内流和C-myc表达可能参与了缺氧性右心室肥大的发生。 相似文献
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镉对小鼠肢芽细胞增殖细胞核抗原和c—myc基因表达的影响 总被引:2,自引:0,他引:2
目的探讨镉对胚胎肢芽细胞增殖抑制的机制。方法运用免疫组化SP法结合图像分析技术观察了CdCl2对增殖细胞核抗原(PCNA)和c-myc基因表达的影响。结果PCNA和c-myc基因在正常增殖的胚胎肢芽细胞中均呈强阳性免疫反应;0.1~0.8μg/mlCdCl2对细胞中PCNA和c-myc的表达均有明显的抑制作用,并呈现明显的剂量-效应关系。结论CdCl2可通过抑制PCNA和c-myc的表达而对胚胎细胞增殖产生抑制作用。 相似文献
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甲基叔丁基醚对原癌基因和功能基因表达的影响 总被引:3,自引:0,他引:3
甲基叔丁基醚(MTBE)是一种新型的汽油添加剂,被用来提高汽油燃烧效率,减少汽车尾气中有害物质的排放。MTBE具有一定的动物致癌性,但其机制目前并不清楚。本研究采用免疫组织化学方法,检测了MTBE对体外培养的NIH3T3细胞中c-myc和p21蛋白表达的影响;采用点杂交方法,从RNA水平检测了MTBE亚慢性染毒大鼠肝组织中原癌基因c-myc基因和功能基因GST-P基因的表达情况。免疫组化结果显示,MTBE可诱导c-myc基因的高表达,对p21蛋白的表达未见明显影响。点杂交结果显示,MTBE可明显诱导大鼠肝组织中c-myc基因的高表达,而对GST-P基因的表达未见明显影响。上述结果提示,MTBE可诱导细胞中c-myc基因表达活性增高,可能是其动物致癌性的机制之一。 相似文献
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茶对小鼠免疫功能的保护作用 总被引:9,自引:0,他引:9
目的探讨茶叶防癌的免疫调节机理。方法用致癌剂4甲基亚硝胺1(3吡啶)1丁酮(NNK)诱发小鼠肿瘤的实验模型,观察NNK所致小鼠免疫功能的改变及绿茶(GT)、复合茶(MT)和茶多酚(TP)的保护作用。结果小鼠注射NNK后,在观察的4周内,腹腔巨噬细胞吞噬功能、外周血白细胞化学发光、迟发型变态反应、脾细胞抗体生成细胞数、以及脾NK活性等免疫指标,与正常对照组比较均出现不同程度的增高或降低;而GT、MT和TP对所有这些免疫功能的不良改变有明显的保护作用。结论茶及其成分对NNK诱发小鼠肿瘤过程中早期所致免疫功能的改变具有保护作用 相似文献
10.
目的甲基叔丁基醚(MTBE)是一种新型的汽油添加剂,动物试验显示其具有一定的致癌性。为了解其动物致癌性的可能机制,我们检测了经MTBE亚慢性染毒的大鼠肝组织中原癌基因cmyc基因和功能基因谷胱甘肽S转移酶P(GSTP)基因的表达情况。方法40只雄性SD大鼠,体重180~200g,随机分为4组。将MTBE溶于适量豆油中,灌胃染毒,染毒剂量分别为200mg/kg,600mg/kg,1000mg/kg和对照组。每天1次,每周5天,共13周。动物肝组织于液氮速冻后,一步法提取总RNA。随机引物法地高辛标记cmyc和GSTP探针,与RNA进行点杂交,图像分析仪分析结果。结果大鼠肝组织中cmyc基因表达水平明显增高,GSTP基因表达未见增强。结论MTBE可明显诱导cmyc基因的高表达,提示其具有促进细胞增殖的作用,这是其动物致癌性的可能机制之一。 相似文献
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Two new complexes ZnL2·2H2O (1) and CuL2·2H2O (2) (HL = 1-hydroxy-6-(2-(1-piperidinyl)ethoxy)xanthone) have been synthesized and characterized. Their interactions with calf thymus DNA (ct DNA) were investigated by absorption spectroscopy, fluorescence spectroscopy, ethidium bromide (EB) displacement experiments, circular dichroism spectroscopy and viscosity measurements. Experimental results suggested that there were intercalative interactions of the complexes with DNA. The binding affinity of complex 2 was higher than that of 1. In addition, the cytotoxic effects of both complexes were evaluated with lung adenocarcinoma (GLC-82), esophagus squamous cancer (ECA109) and human gastric cancer (SGC7901) cells using MTT assay. Both were potent exhibiting significant cytotoxicity in vitro. 相似文献
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目的:探讨1,25-(OH)2D3抑制肝癌细胞增殖的机制。方法:体外培养肝癌细胞株SMMC-7721,培养基因10、50及100(nmol/L)1,25-(OH)2D3作用2d,4d,6d后,用四唑盐比色试验(MTT)和平板克隆形成实验检测细胞的存活和生长;台盼蓝拒染法绘制生长曲线;DNA凝胶电泳检测肝癌细胞凋亡。结果:MTT和平板克隆形成实验检测结果显示10-100nmol/L的1,25-(OH)2D3均对SMMC-7721细胞株有显的抑制作用,且呈剂量-效应关系。DNA凝胶电泳结果显示,1,25-(OH)2D3能够诱导SMMC-7721细胞凋亡。结论:1,25-(OH)2D3对于人肝癌细胞株SMMC-7721的增殖有显的抑制,其机理可能是通过干扰肝癌细胞的DNA代谢和诱导肝癌细胞凋亡。 相似文献
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目的研制一种新型卫生杀虫剂--右旋反式氯丙炔菊酯.方法采用右旋反式DV菊酸与S-炔丙醇酮为原料,经化学拆分、酰氯化及酯化等反应合成右旋反式氯丙炔菊酯,并采用GB/T13917.1-1992和GB/T17322.2-1998标准方法测定了对致倦库蚊和德国小蠊的药效.结果右旋反式氯丙炔菊酯对致倦库蚊及德国小蠊的KT50值分别为8.5 min和3.46min.结论右旋反式氯丙炔菊酯对蚊虫和蟑螂等害虫具有良好的击倒作用和杀灭能力,可以作为一种新型卫生杀虫剂加以推广和应用. 相似文献
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《Nutrition reviews》1978,36(5):154-155
It is postulated that the primary action of vitamin D sterols in the intestine is to enhance the ability of the mucosal cell to accumulate phosphate. 相似文献
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Neithnadka Premsai Rai Venugopala Katharigatta Narayanaswamy Sheena Shashikanth Pirama Nayagam Arunachalam 《European journal of medicinal chemistry》2009,44(11):4522-4527
In the present investigation a series of novel 2-[1-(5-chloro-2-methoxy-phenyl)-5-methyl-1H-pyrazol-4-yl]-5-(substituted-phenyl)-[1,3,4]oxadiazoles (4a–j) were synthesized by cyclization of substituted-benzoic acid N′-[1-(5-chloro-2-methoxy-phenyl)-5-methyl-1H-pyrazole-4-carbonyl]-hydrazide by using phosphorousoxychloride at 120 °C. The chemical structure of the newly synthesized compounds was characterized by analytical and spectral (IR, 1H NMR, 13C NMR and LC–MS) methods. The title compounds were screened for qualitative (zone of inhibition) and quantitative antibacterial activity (MIC) by agar cup plate and microtitration methods, respectively. Among the synthesized compounds in this series compound 2-[1-(5-chloro-2-methoxyphenyl)-5-methyl-1H-pyrazol-4-yl]-5-(4-fluorophenyl)-1,3,4-oxadiazole (4b) was found to exhibit significant antibacterial activity with MICs of 22.4, 29.8, 29.6 and 30.0 μg/mL against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae, respectively. The other compounds exhibited moderate activity when compared to standard substance Ampicillin. 相似文献
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Isocyanate thermal degradation characterization by liquid chromatography coupled with electrospray tandem mass spectrometry has been performed to elucidate the methylene diphenyl diisocyanate (MDI) thermal degradation structure emitted in a generation chamber using a temperature between 50°C and 180°C to produce MDI vapors. [M+H]+ ions containing an isocyanate functional group were studied by tandem mass spectrometry. The [M+H]+ ion analyses based on the combination of full scans and precursor ion scans were useful for identifying all structures. The compounds emitted were identified and validated as a mixture of compounds containing amine and isocyanate functions. Residual MDI, methylene diphenyl amino-isocyanate, and methylene diphenyl diamine were identified. Polymerized forms of these structures were also observed because amine and isocyanate chemical functions react rapidly to polymerize. These results must be used with special care by scientists establishing sensitization diagnostics and developing sampling devices using generation chambers as they must be related to MDI behavior in workplaces. Even if pure MDI is introduced in the generation chamber, several different compounds are generated when the MDI is heated at a high temperature. This can result in some misleading interpretations for non-specific isocyanate sampling device development and sensitization diagnostics as MDI is present in the chamber with other compounds with known adverse effects. 相似文献
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Group B streptococcus (GBS) is a major cause of neonatal sepsis and meningitis. Despite aggressive campaigns using antenatal prophylactic antibiotic therapy, infections continue. Developing an effective maternal vaccine is a public health priority. Antibody (Ab) to the capsular polysaccharide (CPS) is considered the dominant "protective" immune mediator. Here we study the fine specificity and potential host reactivity of a panel of well-characterized murine monoclonal Abs against the type III CPS by examining the binding of the Abs to intact and neuraminidase-digested GBS, purified CPS, synthetic carbohydrate structures, and cells. The results showed marked differences in the fine specificity among these mAbs to a single carbohydrate structure. Cross-reactions with synthetic GD3 and GT3 carbohydrates, representing structures found on surfaces of neural and developing cells, were demonstrated using carbohydrate array technology. The anti-CPS(III) mAbs did not react with cells expressing GD3 and GT3, nor did mAbs specific for the host carbohydrates cross-react with GBS, raising questions about the physiological relevance of this cross-reaction. But in the process of these investigations, we serendipitously demonstrated cross-reactions of some anti-CPS(III) mAbs with antigens, likely carbohydrates, found on human leukocytes. These studies suggest caution in the development of a maternal vaccine to prevent infection by this important human pathogen. 相似文献