电离辐射诱发人肝细胞凋亡的研究

目的 对⁶⁰Coγ射线诱发人正常肝细胞7702凋亡情况进行研究,为探讨辐射诱导细胞凋亡的机制及辐射诱发基因组不稳定性所产生的延迟效应提供重要的实验依据。方法 采用⁶⁰Coγ射线照射人正常肝细胞7702,利用Annexin-V-PI复染法、流式细胞术对辐射诱导细胞凋亡进行检测。结果 首次照射中,照射剂量与细胞凋亡率具有明显的剂量-效应关系;二次照射后的细胞凋亡率与首次照射剂量存在明显的剂量-效应关系;传代细胞的细胞凋亡率与首次照射剂量存在明显的剂量-效应关系。结论 电离辐射诱发细胞凋亡存在明显的剂量-效应关系,辐射使细胞敏感性增加,所产生的损伤使整个基因组处于一种不稳定状态,可以传递到细胞的子代中,持续影响子代细胞的遗传效应。     

^147Pm诱发人白血病细胞凋亡的电镜形态及DNA凝胶电泳研究

研究了受荧光涂料激发能源１４７Ｐｍ 辐照人白血病ＨＬ－ ６０ 细胞所诱发的细胞凋亡。实验中估算了１４７Ｐｍ 在不同阶段培养细胞中的辐射累积吸收剂量。通过透射电镜的形态观察,发现当ＨＬ－６０ 细胞在受１４７Ｐｍ 辐照时,可诱发明显的核断裂、核边聚,以及呈现膜包裹着的凋亡小体形成为特征的细胞凋亡。进而抽提了ＨＬ－ ６０ 细胞的ＤＮＡ,进行琼脂糖凝胶电泳观察,显示出阶梯状条带形成的细胞凋亡特征。从而提示了１４７Ｐｍ 辐照可导致人白血病ＨＬ－ ６０ 细胞凋亡。     

喉癌自发性与放射诱发细胞凋亡关系的研究

目的通过对细胞凋亡情况进行检测,对比探讨喉癌自发性及放射诱发凋亡情况,以及两者之间的关系。从而分析喉癌的最佳放射治疗剂量。通过研究喉癌自发性与放射诱发细胞凋亡关系及其临床应用。观察喉癌放疗前及放疗中细胞凋亡的变化及其意义,从细胞凋亡的角度重新认识喉癌,从而指导临床喉癌放疗剂量与水准,对于早期喉癌患者在保存其各种生理功能的前提下治疗甚至治愈肿瘤。对于早期喉癌患者在保存     

浓缩铀诱发培养免疫细胞凋亡的电镜观察及CHX和ActD的防护作用

对浓缩铀＾２３５Ｕ内照射人淋巴细胞白血病细胞株Ｍｏｌｔ－４细胞和巨噬细胞株Ａｎａ－１细胞诱发的细胞凋亡及其防护因子进行了研究，实验中估算了＾２３５Ｕ在不同阶段培养细胞中的辐射累积吸收剂量，通过透射电镜的形态观察，发现Ｍｏｌｔ－４和Ａｎａ－１两株免疫细胞在受＾２３５Ｕ内照射作用下，可诱发核断裂，核染质边聚，以及呈现膜包裹着的凋亡小体形成的特征的细胞凋亡，而蛋白质合成抑制剂ＣＨＸ和ＲＮＡ的合成抑制剂，     

浓缩铀诱发细胞凋亡的形态及基因调控

目的　研究浓缩铀诱发人白血病HL 6 0细胞凋亡的电镜形态特征 ,以及对相关基因bcl 2和bax的调控作用。方法　探讨受浓缩铀内照射不同时间 ,诱发HL 6 0细胞凋亡的电镜形态 ;运用免疫组织化学技术探讨浓缩铀对HL 6 0细胞bcl 2和bax蛋白的表达 ,运用RNA分子杂交技术探讨浓缩铀对HL 6 0细胞bcl 2mRNA的转录水平表达的影响。结果　人白血病HL 6 0细胞在浓缩铀辐照作用下 ,可呈现核断裂和核染质边聚。对照的HL 6 0细胞中bcl 2蛋白呈高度表达 ,为 (88± 7) % ,而受浓缩铀辐照下 ,可下调至(6 1± 5 ) %。bax在对照细胞中表达很低 ,在浓缩铀作用下 ,未见明显改变。经浓缩铀辐照后 ,可使HL 6 0细胞中的bcl 2mRNA表达呈明显下调。结论　浓缩铀内照射可诱发人白血病HL 6 0细胞凋亡发生 ,且其诱发HL 6 0细胞的凋亡作用与其下调凋亡相关基因bcl 2的表达相关联     

氯化镉诱发肾上腺皮质细胞凋亡与应激活化蛋白激酶活性的 …

目的 了解氯化镉诱发肾上腺皮质细胞凋亡的发生及应激活化蛋白激酶（ＳＡＰＫ）活性的变化。方法 体外分离培养豚鼠肾上腺皮质细胞,以蛋白因子添加素Ⅴ和碘化丙啶联合标记,流式细胞仪检测,观察氯化镉诱发细胞凋亡的特征;采用免疫沉淀－化学发光法测定ＳＡＰＫ活性。结果 ６．２５～２００．００μｍｏｌ／Ｌ剂量氯化镉处理２ｈ,凋亡细胞百分率随剂量增加而增加,平均为９．９０％、１５．４７％、３３．６７％、５３．７０％     

不同浓度幽门螺杆菌对胃癌上皮细胞SGC-7901生长的影响

[目的]探讨幽门螺杆菌(Helicobacter pylori,Hp)对体外培养胃上皮细胞的增殖与凋亡作用.[方法]6种浓度Hp标准株NCTC11637分别感染SGC-7901细胞,观察细胞形态,测定增殖细胞核抗原(PCNA)表达、细胞增殖指数(PI)和凋亡率.[结果](1)Hp感染细胞形态均出现早期细胞凋亡的特征性改变; (2)Hp≥9.6×105 cfu/ml时,细胞凋亡率显著升高(P＜0.01); (3)细胞PCNA表达率和PI在Hp≤1.9×105 cfu/ml时明显增高(P＜0.05);而Hp≥4.8×106 cfu/ml时显著降低(P＜0.05).[结论]Hp感染可直接诱发胃上皮细胞的增殖与凋亡,增殖与凋亡的菌量依赖性不同.     

氯化镉诱发肾上腺皮质细胞凋亡与蛋白激酶B活力的关系

目的 了解氯化镉(CdCl2)诱发肾上腺皮质细胞凋亡的发生与蛋白激酶B(protein kinase B,PKB,又称Akt)活力变化的关系.方法 体外分离培养豚鼠肾上腺皮质细胞,以蛋白因子添加素V和碘化丙啶联合标记,流式细胞仪检测,观察CdCl2诱发细胞凋亡的特征;采用免疫沉淀-化学发光法测定PKB/Akt活力.结果 6.25～100.00 μmol/L剂量CdCl2处理肾上腺皮质细胞2 h,细胞凋亡发生率随剂量增加而增加,25.00 μmol/L及更高剂量组与对照组比较,差异有统计学意义(P＜0.01);回归分析表明,CdCl2剂量与凋亡发生率呈剂量-效应关系.以50.00 μmol/L CdCl2处理细胞,细胞凋亡发生率随时间的延长而增加,CdCl2作用15 min～4h,平均凋亡率为5.58%-73.08%,其中1、2、4h时间点与对照相比,差异有统计学意义(P＜0.05);CdCl2处理时间与凋亡发生率呈时间-效应关系.6.25～200.00 μmol/L剂量CdCl2处理30 min,显示CdCl2可引起肾上腺皮质细胞PKB/Akt表达降低,在一定剂量范围内呈线性关系.结论 CdCl2诱发肾上腺皮质细胞凋亡的同时引起细胞内PKB/Akt表达水平的降低.     

细胞凋亡与卵巢肿瘤

细胞凋亡是与坏死不同的另一种细胞死亡,研究发现其与肿瘤的发生及治疗关系密切。本文概述了细胞凋亡与卵巢肿瘤的关系。     

细胞凋亡与肿瘤的发生

细胞凋亡是一种凋亡相关基因调控的自身程序化死亡,是细胞有序而协调激活凋亡刺激基因和凋亡抑制基因双向共同调控的过程.随着细胞凋亡研究的深入,人类逐渐认识到细胞凋亡与肿瘤的发生密切相关,并成为当今研究热点之一.     

The Effect of In Vitro Exposure to Tributyltin on the Immune Competence of Chinook Salmon (Oncorhynchus tshawytscha) Leukocytes

We evaluated the direct effects of in vitro exposures to tributyltin (TBT), a widely used biocide, on the cell-mediated immune system of Chinook salmon (Oncorhynchus tshawytscha). Splenic and pronephric leukocytes isolated from juvenile Chinook salmon were exposed to TBT (0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 mg/l) in cell cultures for 24 h. Effects of TBT on cell viability, induction of apoptosis, and mitogenic responses were measured by flow cytometry. Splenic and pronephric leukocytes in the presence of TBT experienced a concentration-dependent decrease in viability in cell cultures. Apoptosis was detected as one of the mechanisms of cell death after TBT exposure. In addition, pronephric lymphocytes exhibited a greater sensitivity to TBT exposure than pronephric granulocytes. The functional ability of splenic B-cells to undergo blastogenesis upon lipopolysaccharide stimulation was also significantly inhibited in the presence of 0.05, 0.07, or 0.10 mg/l of TBT in the cell cultures. Flow cytometric assay using a fluorescent conjugated monoclonal antibody against salmon surface immunoglobulin was employed for the conclusive identification of B-cells in the Chinook salmon leukocytes. Our findings suggest that adverse effects of TBT on the function or development of fish immune systems could lead to an increase in disease susceptibility and its subsequent ecological implications.     

Effects of tributyltin, benzo[a]pyrene, and their mixture on antioxidant defense systems in Sebastiscus marmoratus

It has been reported that there is a metabolic interaction between tributyltin (TBT), an organometal used as an antifouling biocide, and benzo[a]pyrene (BaP), a widespread carcinogenic polycyclic aromatic hydrocarbon. This study was therefore designed to examine the potential in vivo influence of TBT, BaP, and their mixture on hepatic antioxidant defense systems of Sebastiscus marmoratus, which were given a single ip injection of TBT (0.5, 1, 5, and 10mg/kg), BaP (0.5, 1, 5, and 10mg/kg), or both in combination (0.5, 1, 5, and 10mg/kg); control fish received olive oil vehicle only. Samples were collected for biochemical analysis after injection for 7 days. Cotreatment with BaP caused a significant inhibition of TBT-mediated malondialdehyde contents elevation. Cotreatment with TBT decreased BaP-mediated glutathione peroxidase activity induction. Cotreatment with TBT and BaP did not significantly alter the reduced glutathione levels, which were significantly induced by TBT or BaP alone. TBT-induced suppression of BaP bioactivation or BaP-induced stimulation of the phase II metabolism of TBT and its biliary excretion, both of which have been reported previously, could explain the observed antagonism. The results suggest that combined exposure of TBT and BaP increases the vulnerability of the fish to oxidative stress. BaP cotreatment decreased the induction of glutathione S-transferase (GST) activity by the lower dose of TBT, while cotreatment with TBT and BaP at the highest dose (10mg/kg) resulted in inhibition of the GST activity by 4.8-fold. The results suggest that these biomarkers should be interpreted with caution in biomonitoring studies. Combined effects of TBT and BaP exposure at environmental levels on these biomarkers should be further researched.     

Horizontal and vertical distribution of butyltin compounds in sediments from shipyards in Korea

Butyltin compounds were quantitatively determined in surface sediment and sediment core samples near shipyards in the south coast of Korea, which is one of the major ship building industries in the world. Tributyltin (TBT) concentrations reached up to 46,100 ng Sn/g on a dry-weight basis at the front of the shipyard. Horizontal distribution of butyltin compounds was closely related to dry-docking activities. Butyltin concentrations were relatively low where remote from the sources. The vertical distribution of TBT in sediment cores showed active use of TBT in Korean peninsula for the past decades. The increase of TBT concentrations in sediment core according to estimated sediment age demonstrated a positive correlation with the increase of gross tonnage of ships built in the shipyard for 20 years. High TBT residue levels in sediment core samples raise concerns over persistence of the compound in the marine environment. Received: 2 August 2001/Accepted: 25 March 2002     

Tributyltin-sulfhydryl interaction as a cause of immunotoxicity in phagocytes of tunicates

We reported elsewhere that tributyltin (TBT) has detrimental effects on the immune system of the colonial ascidian Botryllus schlosseri, through interaction with calmodulin and alteration of Ca2+ homeostasis. Here, we studied the capability of TBT to react with intracellular thiols. After exposure to 0.1 microM TBT, a significant decrease in B. schlosseri hemocytes stained for total thiols and reduced glutathione (GSH) was detected. Exogenous sulfhydryl and sulfide compounds can prevent TBT-induced cell morphology alterations and decrease the percentage of tin-containing hemocytes, indicating the scavenging ability of thiol peptides. No effects were observed with disulfides, N-acetylcysteine, or the GSH fragment Cys-Gly. No interactions were observed with TBT and carmustine, whereas TBT and N-ethylmaleimide (NEM) showed a combined antagonistic action, suggesting direct interaction of TBT with thiol-containing compounds. Regulation of Ca2+ efflux from internal stores seems to depend on stimulation of the inositol 1,4,5-trisphosphate (InsP3) receptor by oxidized glutathione (GSSG), which results from interactions of both TBT-GSH and TBT-GSH reductase.     

Butyltin accumulation in two marine bivalves along a pollution gradient

In the present study, we describe a field survey regarding the effect of ambient water conditions in the accumulation of tributyltin (TBT) and its metabolites in green mussels (Perna viridis) and Pacific oysters (Crassostrea gigas). The results showed that following the changes in TBT pollution levels, the accumulation of butyltins exhibited clear differences between oysters and mussels. The ratio of TBT to total butyltin (TBT:SigmaBT) decreased from 0.87 to 0.31 with increasing TBT burdens in the oysters. This status suggests that following the increases of TBT burdens, the metabolic rates of TBT were clearly enhanced in oysters; however, this phenomenon was not shown in mussels. The TBT:SigmaBT remained relatively constant at approximately 0.7 in the mussels despite the TBT burdens. Because of this phenomenon, the opposite status of different TBT burdens between oysters and mussels were present at different TBT pollution levels. These observations may provide valuable insight when evaluating or comparing TBT pollution in the environment using oysters and/or mussels as bioindicators.     

Alteration of [14C]-Testosterone Metabolism After Chronic Exposure of Daphnia magna to Tributyltin

Tributyltin (TBT) is a marine biocide that has been shown to alter the activity of cytochrome P450 monooxygenases and elicit toxicity indicative of androgenization in some species. The present study was conducted to determine whether TBT altered P450-, reductase-, and transferase-mediated testosterone metabolic processes in Daphnia magna at sublethal exposure concentrations. Two generations of daphnids were continuously exposed for 21 days to nominal TBT concentrations ranging from 0.31 to 2.5 μg/L TBT. The highest TBT concentration (2.5 μg/L) was lethal to 60% of the exposed organisms. Lower TBT concentrations elicited no adverse effects on molting or reproduction of the daphnids. No differences were observed in the response of the first- and second-generation daphnids to the toxicity of TBT. The ability of daphnids to metabolize [¹⁴C]-testosterone in vivo was assessed following exposure of each generation to TBT. Production of hydroxylated, reduced/dehydrogenated, and glucose-conjugated metabolites of testosterone were all elevated following exposure of both generations to 1.25 μg/L TBT. These findings indicate that, under these conditions, TBT elicits no discernible effects on molting and reproduction of daphnids at sublethal concentrations, and testosterone metabolism is enhanced at concentrations approaching those that are lethal to organisms. Alterations of steroid metabolism by xenobiotics can be used as a more sensitive indicator of sublethal exposure in daphnids than reproductive endpoints. Received: 10 March 1997/Accepted: 27 May 1997     

Effects of tributyltin exposure in hermit crabs: Clibanarius vittatus as a model

Tributyltin (TBT) contamination affects the reproductive system of many species of invertebrates worldwide. The present study was designed to evaluate the effects of exposure to TBT pollution on the reproduction of the hermit crab Clibanarius vittatus. An orthogonal experiment was designed with two treatments: contamination (with or without TBT in the food) and crab sex (males and females). The animals were reared in the laboratory for nine months, and macroscopic and histological analyses of reproductive organs were carried out after the end of the experiment. Tributyltin was recorded in exposed crabs, but no morphological alterations were detected in the gonads of males, regardless of whether they were exposed to TBT. In contrast, females exposed to TBT displayed disorganization and atrophy of their ovaries, thus directly affecting reproduction in this hermit crab species. This effect observed in female hermit crabs may harm populations located in harbor regions, where TBT concentration is high, even after the worldwide TBT ban.     

Reed beds may facilitate transfer of tributyltin from aquatic to terrestrial ecosystems through insect vectors in the Archipelago Sea, SW Finland

Due to their adsorptive behavior, organotin compounds (OTCs), such as tributyltin (TBT), are accumulated in aquatic sediments. They resist biodegradation and, despite a ban in 2008, are a potential source for future exposure. Sediment OTCs have mostly been measured from sites of known high concentrations such as ports, shipping lanes, and marine dredging waste sites. The possible flow of OTCs from marine to terrestrial ecosystems, however, has not been studied. In the present study, the authors assessed whether sediments in common reed beds (Phragmites australis) accumulate TBT and whether chironomid (Diptera: Chironomidae) communities developing in reed-bed sediments act as vectors in the transfer of TBT from aquatic to terrestrial ecosystems in the Airisto channel, Archipelago Sea. The authors also investigated whether distance from the only known source and depth and TBT concentration of the adjacent shipping lane affect reed-bed concentrations. Thirty-six sites along the Airisto channel were sampled at 2-km intervals with triplicate samples from reed beds and the adjacent shipping lane for sediment and seven reed-bed sites for chironomids, and these were analyzed with an solid phase extraction liquid chromatography tamdem mass spectrometry method. The closer to the source the sample site was, the higher the measured TBT concentrations were; and the deeper the shipping lane, the lower the concentration of TBT in reed-bed sediments. The chironomid TBT concentrations correlated with reed-bed sediment TBT concentrations and showed evidence of accumulation. Therefore, TBT may be transferred, through the food web, from aquatic to terrestrial ecosystems relatively close to a source through ecosystem boundaries, such as common reed beds, which are areas of high insect biomass production in the Archipelago Sea.     

Tributyltin uptake and depuration in Hyalella azteca: implications for experimental design

The purpose of this study was to address four aspects of the kinetics of tributyltin (TBT) in the freshwater amphipod Hyalella azteca: time to steady state, route of uptake, depuration rates, and effect of gut clearance. The amphipods accumulated TBT rapidly, reaching steady state within 14 d. Body concentrations were similar between caged and sediment-exposed animals, indicating that the primary route of uptake is via dissolved TBT. However, the rate of uptake was significantly higher in sediment-exposed amphipods. During depuration, body concentrations of TBT exhibited a biphasic decline, with a stronger decrease over the first 24 h that is attributed primarily to gut clearance, followed by a more gradual decrease most likely due to excretion from the body. Gut contents contributed significantly to body concentrations of TBT, accounting for 30% of the initial total body burden in sediment-exposed amphipods. Half-lives of TBT in gut-cleared H. azteca were 8 d and 14 d for amphipods exposed to spiked water and spiked sediment, respectively. The results of this study have significant implications in the experimental design and interpretation of studies involving the effects of TBT in H. azteca.