TCDD对乳腺癌细胞端粒酶活性的影响

探讨了2,3,7,8-四氯二苯并-ρ-二噁英(TCDD)在体外对雌激素依赖性乳腺癌细胞MCF-7端粒酶活性的影响.用0.5μmol·L-1的2,3,7,8-四氯二苯并-ρ二噁英(TCDD)作用于MCF-7细胞,裂解后提取MCF.7细胞端粒酶.采用BCA方法定量蛋白、重复序列扩增-银染法检测端粒酶活性.结果表明.TCDD作用MCF-7细胞后,细胞端粒酶活性增强,且随作用时间端粒酶活性减弱,但明显高于对照组(P<0.05).结果表明:TCDD有显著增强MCF-7细胞端粒酶活性的作用.     

Assessing possible exposures of ground troops to agent orange during the vietnam War: The use of contemporary military records

BACKGROUND: Potential exposure of ground troops in Vietnam to Agent Orange and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) remains controversial despite the passage of 30 years since the Vietnam War. Because of uncertainty over the serum dioxin levels in ground troops at the end of their service in Vietnam, attempts have been made to develop a methodology for characterizing exposure of ground troops in Vietnam to Agent Orange and other herbicides based upon historical reconstruction from military records. Historical information is often useful in evaluating and modeling exposure, but such information should be reasonably accurate, complete, and reliable. METHODS: This paper reviews the procedures and supporting historical information related to the spraying of herbicides in Vietnam. The historical information is classified into two categories: procedural information and operational information. Procedural information covered the process and procedures followed in spraying herbicides from US Air Force fixed wing aircraft (Operation RANCH HAND) in Vietnam, and included approval procedures for spray missions, the criteria required to conduct a mission, the control exercised by the Forward Air Controller and the Tactical Air Control Center and the characteristics of the equipment used to apply the herbicides. Operational information includes data from the RANCH HAND Daily Air Activities Reports, which included geographic locations of specific spray missions, the amount of herbicide sprayed by a specific mission, reports of battle damage to spray aircraft, reports of fighter aircraft support for aerial spray missions, and any comments, such as reasons for canceling a mission. RESULTS: Historical information demonstrates that herbicide spray missions were carefully planned and that spraying only occurred when friendly forces were not located in the target area. RANCH HAND spray missions were either not approved or cancelled if approved when there were friendly forces in the area designated for spraying. Stringent criteria had to be met before spray missions could be approved. The operational information shows that spray missions for both defoliation and crop destruction were conducted in an extremely hostile environment. Heavy 'fighter suppression' with antipersonnel ordnance was used to minimize the impact of hostile ground fire on RANCH HAND aircraft. Procedures were in place that prohibited movement of troops into sprayed areas immediately after a mission due to the possible presence of unexploded ordnance delivered by fighter aircraft supporting RANCH HAND missions. The optimal nature of the spray equipment and application procedures minimized the possibility of significant spray drift. Conclusions. Few friendly troops were sprayed by fixed wing aircraft during Operation RANCH HAND, which delivered 95% of all defoliants used in Vietnam. Similarly, few troops were sprayed during helicopter or surface-based spray operations, which constituted the remaining 5% of defoliants. Detailed policies and procedures for approval and execution of spray missions ensured that friendly forces were not located in the areas targeted for spraying. Fighter aircraft assigned to accompany each spray mission frequently suppressed much of the hostile fire with bombs and other ordnance. Confirmed clearance of the target area was necessary to avoid friendly casualties. Historical records establish that these policies and procedures were strictly followed. Exposure of troops whether from direct spraying or movement through areas recently sprayed was very unlikely. The wartime military records of troop positions and herbicide operations are valuable for some purposes, but have specific limitations in exposure reconstruction. The completeness and accuracy of the geographic data (maps used by RANCH HAND and military ground units) were dependent upon the inherent precision of the map, the accuracy with which it depicted surface features, and the completeness and accuracy of the information on which it is based. Navigation by the crew using visual orientation and reference to the map was the only means that aircrew on spray missions had for establishing their locations. A Forward Air Controller independent of Operation RANCH HAND was present at the location of each spray target immediately before and during spraying operations to verify the target location and ensure that friendly forces were clear of the target area. Anecdotal reports of direct spraying of troops in Vietnam likely reflect the RANCH HAND missions spraying insecticide for mosquito control at regular intervals from March 1967 through February 1972. Outlook. The distribution and levels of serum dioxin in RANCH HAND veterans and the US Army Chemical Corps Vietnam veterans (the unit responsible for helicopter and ground-based spray operations) are distinguishable from typical levels in the population decades after the Vietnam conflict. An exposure model similar to that proposed in the 2003 report of the Institute of Medicine's Committee on 'Characterizing Exposure of Veterans to Agent Orange and Other Herbicides Used in Vietnam' was tested in 1988 by the Centers for Disease Control and Prevention and found to be a poor predictor of absorbed dose of TCDD. Military records during the Vietnam War lack the precision to determine that troops were directly sprayed with herbicides during Operation RANCH HAND, especially given the procedures in place to ensure clearance of friendly forces from the target area and the lack of elevated serum levels of TCDD in ground troops judged to have operated in heavily sprayed areas.     

13C同位素稀释法测定国产多氯联苯的2,3,7,8－TCDD毒性当量

应用质量控制方法测定了２种国产商品多氯联苯中１７个，２，３，７，８位有氯取代的二ｅｙｉｎｇ同族体，获得准确的定量结果，加入＾１３Ｃ标记物的ＰＣＢｓ样品用多级酸碱硅胶柱和氧化铝柱提取分离，用毛细管色谱／高分辨质谱定量，２种样品中都含有较多的２，３，７，８－ＴＣＤＦ和２，３，７，８Ｐ５ＣＤＦ，１＾＃ＰＣＢ的２，３，７，８－ＴＣＤＤ毒性当量值为２１７ｎｇ／ｇ，２＾＃ＰＣＢ为４１７ｎｇ／ｇ，毒性主要来自Ｐ     

吉林省典型湖库中无机氮含量变化规律初探

通过对吉林省典型湖库1992－1997年的连续水质水文监测，探讨了吉林省主要湖库中无机氮含量的季节变化、年际变化规律及其成因，吉林省大多数湖库中的总氮处于中等富营养化程度，城市湖库（南湖）已超过富营养水平下降，受到外源性补给、温度和湖库使用功能的影响，湖库中各类型无机氮含量季节变化不一，总氮在全年出现波状起伏变化，大多数湖库中的无机氮和总氮出现逐年增加的趋势，湖库中无机氮含量受到水体中各种水质因素的综合作用。与其它单个水质之间的关系不明显。     

~（13）C同位素稀释法测定国产多氯联苯的2，3，7，8－TCDD毒性当量

应用质量控制方法测定了２种国产商品多氯联苯（ＰＣＢｓ）中１７个２，３，７，８位有氯取代的二　同族体，获得准确的定量结果，加入￣（１３）Ｃ标记物的ＰＣＢｓ样品用多级酸碱硅胶柱和氧化铝柱提取分离，用毛细管色谱／高分辨质谱定量，２种样品中都含有较多的２，３，７，８－ＴＣＤＦ和２，３，７，８－Ｐ＿５ＣＤＦ。１￣＃ＰＣＢ的２，３，７，８－ＴＣＤＤ毒性当量值为２１７ｎｇ／ｇ，２￣＃ＰＣＢ为４１７ｎｇ／ｇ，毒性主要来自ＰＣＤＦｓ，并与国外同类商品ＰＣＢｓ作了比较。     

Trisomy 8 mosaicism in chorionic villus sampling: Case report and counselling issues

We report an unusual case involving chorionic villus sampling (CVS) and trisomy 8 mosaicism. CVS showed a normal direct preparation while the culture showed mosaicism for trisomy 8. Subsequent amniocentesis revealed only normal chromosomes. A peripheral blood culture after birth revealed low-level trisomy 8 mosaicism. The patient appeared phenotypically and developmentally normal at 30 months of age. We conclude that prenatal counselling for similar cases needs to include the rare but real possibility that chromosome mosaicism detected prenatally may be found postnatally with largely unknown consequences. Secondly, low-level chromosomal mosaicism may be more common than previously recognized. Thirdly, very low-level trisomy 8 mosaicism may be compatible with a normal phenotype but long-term follow-up is required. And lastly, the use of fetal blood sampling is questionable in these cases because the phenotype may not be accurately predicted. Further studies of such cases are needed to address these important and unanswered issues, including the potential implication of mosaicism on academic performance and cognitive functioning.     

中国臭氧时空分布特征及与社会经济因素影响分析

本文根据2015～2017年中国大陆338个城市空气质量监测站臭氧(O_3)浓度数据,综合利用空间插值法、全局自相关法和地理加权回归模型(GWR),探讨了O_3浓度的时空变化特征及其与社会经济因素的关系。结果表明,2015～2017年中国大陆338个城市的O_3日最大8小时浓度为2～300μg/m~3,其中超标天数比例为5. 9%,323个城市达标率在85%以上; O_3月均值变化曲线基本呈"单峰状",5月达到峰值,12月最低; O_3浓度季节变化为夏季春季秋季冬季; O_3日变化特征为夜间到清晨O_3浓度很低,上午8∶00左右开始升高,下午16∶00达到峰值;中国华北地区、华东地区和华中地区O_3污染严重,华南地区、西南地区、西北地区和东北地区整体污染较低。O_3浓度在全国尺度上的集聚性呈上升趋势,GWR表明,人口密度、人均私家车保有量与O_3浓度显著正相关,第一产业占比与O_3浓度显著负相关。     

基于Landsat-8的城市湖泊水体总悬浮物吸收系数的遥感反演——以杭州西湖为例

近年来城市湖泊水质受到广泛关注.总悬浮物(total suspended matter,TSM)是水质和水环境评价的重要参数之一,其直接决定着水下光场分布,进而影响水体的初级生产力.本研究基于在杭州西湖的各湖区收集的遥感反射率(R_(rs),sr~(-1))数据和总悬浮物的吸收系数(a_p(440),m~(-1))进行高光谱建模,比较不同经验函数形式和不同模型输入的效果,得到高光谱下的最佳函数是指数函数,最佳模型输入是B1/B2或(B1-B2)/(B1+B2).其中,当模型输入为B1/B2和(B1-B2)/(B1+B2)时,模型R~20.6,波段B1和B2范围分别是580～690 nm和515～535 nm,及700～720 nm和515～615 nm.参照最佳波段范围和Landsat-8的波段设置,选定Landsat-8红色和绿色波段反演模型.并根据卫星数据验证结果,选定最优模型a_p(440)=51.17e~(-7.75x),x=(OLI3-OLI4)/(OLI3+OLI4),在3幅Landsat-8图像上应用模型,观察西湖TSM的变化.研究结果发现人类活动可能对西湖的TSM有很大的影响,并且我们的研究和结果有望为未来城市湖泊水质管理提供方法、数据和指导.     

欧洲规范关于延性桥梁抗震设计方法的安全性评价

评价了欧洲桥梁抗震设计规范 (Eurocode 8,part2 ) [1] 关于延性桥梁抗震设计方法的安全性。以一座高架桥横向抗震设计为例 ,按 3个不同的性能系数设计圆柱式桥墩 ,根据欧规规定的最小配箍率配置箍筋 ,使用自编程序MCAP[2 ] 评价其实际达到的延性水平 ,并通过非线性时程分析评价其抗震性能。结果表明 ,欧洲规范规定的最小配箍率足以保证结构达到预期的最低延性能力 ,性能系数具有相当大的安全储备。同时可以借鉴欧洲规范 ,作为延性桥梁抗震设计的一种安全设计方法。     

Enhanced hepatotoxicity induced by repeated exposure to polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin in combination in male rats

2,3,7,8-Tetrachlorodibenzo-p-dioxin(TCDD) and polychlorinated biphenyls(PCBs) are among persistent polyhalogenated aromatic hydrocarbons that exist as complex mixtures in the environment worldwide.The present study was attempted to investigate the hepatotoxicity following repeated exposure to TCDD and PCBs in combination in male rats,and to reveal the involvement of potential mechanisms.Male Sprague-Dawley rats were exposed to TCDD(10 μg/kg) and Aroclor 1254(10 mg/kg,a representative mixture of PCBs) alone ...