高场强电磁脉冲辐射对小鼠肝细胞DNA含量和倍体影响的定量学研究

目的　动态观察高场强电磁脉冲辐射 (EMP)对小鼠肝细胞核DNA含量及倍体的影响 ,探讨电磁辐射的生物学效应。方法　应用高场强EMP发射源对二级昆明小鼠进行全身辐射 ,场强分别选用 8× 10 3、2× 10 4 和 6× 10 4 V m ,发射源相关技术参数 :脉冲上升时间 2 0ns,脉宽 30 μs ,2min内发射 5个单脉冲 ;采用Feulgen染色动态观察小鼠肝细胞核内DNA含量的变化 ,观察时间 1年 ,共设 10个时相点 (n =6 ) ,并用德国IBSA显微数字图像分析系统作DNA含量定量分析和倍体分型。结果　小鼠经高场强EMP辐射后 3个月内 ,肝细胞核DNA含量与正常对照组差异无显著性 ,以二倍体细胞 (2C)为主 ,四、六倍体 (4C ,6C)较少 ,八倍体 (8C)偶见 ;辐射后 6个月 ,8× 10 3V m辐射组比对照组DNA含量高 (P <0 0 5 ) ,2C数量减少 ,4C和 6C增加 ;至辐射后 9个月和 12个月 ,各辐射组肝细胞核DNA含量比其他各时相点辐射组及同一时相点对照组显著增高 (P <0 0 1) ,并且以 4C为主 ,6C和 8C增加 ,而 2C明显减少。结论　高场强EMP对小鼠肝DNA含量及倍体有影响 ,且表现为远后效应 ,推测电磁辐射对肝的生物学效应中肝细胞核酸可能是一个重要的靶点 ,这将为进一步研究其损伤效应及其作用机制提供实验性依据。此外 ,本研究结果提示要注重电磁辐射远     

α粒子辐射对ROS介导src激酶活性和自噬的影响

目的 通过检测人胚肾上皮细胞HEK293受不同剂量α粒子照射后,src激酶活性和细胞自噬系统的变化,探讨调控细胞自噬对高剂量辐射诱导细胞死亡的影响.方法 将人胚肾上皮细胞HEK293分为3组:0 cGy(对照)组、241Am α粒子照射低剂量(10 cGy)组和高剂量(300 cGy)组.应用免疫印迹实验检测细胞内源性蛋白LC3Ⅰ/Ⅱ和src激酶的变化;分子探针检测细胞内活性氧(ROS)水平;用ROS淬灭剂DMSO预处理照射细胞,并用免疫印迹法检测照射后src激酶的变化;使用自噬诱导剂雷帕霉素预处理照射细胞,以PI染色流式细胞术测定细胞死亡率.结果 与0 cGy相比,10 cGy α射线照射后LC3 Ⅰ/Ⅱ比例降低(=4.07,P＜0.05),胞质内具有绿色荧光点状GFP-LC3的细胞比例升高(t=12.29,P＜0.05),自噬被诱导;而300 cGy照射后,LC3Ⅰ/Ⅱ比例升高(t=2.93,P＜0.05),胞质内GFP-LC3形态无明显变化,自噬被抑制.与0 cGy相比,10和300 cGy照射后4h均能提升细胞内ROS水平(t=17.93、22.88,P＜0.05),且300 cGy比10 cGy照射诱发的ROS更多(t=15.76、22.66、14.22,P＜0.05).与0 cGy相比,10 cGy照射使src激酶419位酪氨酸磷酸化水平升高(t=5.66,P＜0.05),而300 cGy照射则降低其磷酸化水平(=4.67,P＜0.05).DMSO能够部分逆转高低剂量照射对src激酶活性的影响.辐照前以自噬诱导剂雷帕霉素处理细胞则能降低300 cGy照射诱发的细胞死亡率(t=12.14,P＜0.05).结论 高低剂量α粒子分别抑制和激活src激酶以及细胞自噬,ROS参与介导辐照对src激酶活性及自噬系统的影响.对自噬系统的干预能够降低细胞的辐射敏感性.     

125I粒子持续照射对Sw1990及Panc-1细胞生物学效应的影响

目的采用125I粒子对胰腺癌细胞Sw1990及Panc-1行体外持续照射,研究其生物学效应,探讨连续照射对胰腺癌细胞增殖、DNA合成、细胞周期及凋亡的影响,并为胰腺癌放射实验细胞的选择提供参考。方法将胰腺癌细胞Sw1990及Panc-1体外培养至对数生长期,行125I粒子持续照射,在初始剂量率为12.13 cGy/h时,分别给予总剂量为0、2、4、6、8 Gy的照射,采用克隆形成实验检测照射后细胞的增殖能力,绘制生存曲线,计算细胞存活率(SF2),检测细胞凋亡率和细胞周期,以及3H-TDR掺入实验探究照射后细胞DNA合成情况。结果经过拟合,计算出Sw1990和Panc-1细胞的SF2值分别为0.766±0.063和0.729±0.045,随着照射剂量增高,两种细胞凋亡率也逐渐升高,Panc-1细胞的最大凋亡率出现在6 Gy,Sw1990出现在8 Gy。G2/M期阻滞分数均逐渐升高,3H-TDR掺入放射量逐渐降低。结论125I持续照射胰腺癌细胞时,细胞凋亡及G2/M期阻滞是抑制细胞增殖的主要原因,在剂量为0、2、4、6、8 Gy时,Sw1990及Panc-1细胞生物学效应差异无统计学意义。     

细胞种类及孵育时间对血卟啉单甲醚在细胞内分布的影响

目的探讨细胞种类和孵育时间对光敏剂血卟啉单甲醚(HMME)在细胞内分布的影响。方法传代培养小鼠肺内皮细胞(1H11)和A549肺癌细胞,分别与光敏剂HMME孵育2h和12h。应用由荧光显微镜及CCD组成的高分辨率荧光显微成像系统,结合荧光探针标记技术,采用细胞器-细胞荧光强度比值法研究HMME在不同条件下的亚细胞分布情况。结果在2h和12h2个孵育时间点高尔基体的J1/J2值都最高;随着孵育时间延长,A549细胞的4种细胞器的J1/J2值都升高且溶酶体幅度最大,而小鼠肺内皮细胞只有溶酶体的J1/J2值呈升高趋势,高尔基体、内质网和线粒体等细胞器的J1/J2值均呈下降趋势;A549细胞溶酶体的J1/J2值升高的幅度明显高于鼠肺内皮细胞。结论HMME在不同种类细胞内的亚细胞分布是不同的。孵育时间对HMME亚细胞分布的影响显著。随着孵育时间的延长,A549肺癌细胞各细胞器吸收HMME能力逐渐增强,尤以溶酶体显著;小鼠肺内皮细胞中除溶酶体外各细胞器吸收HMME能力逐渐减弱。孵育12h后,A549肺癌细胞各细胞器吸收HMME能力均强于鼠肺内皮细胞。     

血卟啉单甲醚光动力学疗法对体外培养的人角质形成细胞增生的影响

目的观察人角质形成细胞株Hacat对血卟啉单甲醚(hematoporphyrinmonomethylether,HMME)的吸收特性及HMME-PDT对角质形成细胞增生的影响。方法对数生长期的Hacat细胞分别与浓度为0、10、20和40μg/ml的HMME孵育1h;同时将另一实验组的Hacat细胞与10μg/ml的HMME分别孵育0和30min、1和2h,分别以流式细胞仪检测孵育时间和孵育浓度对Hacat细胞吸收HMME的影响;在此基础上,将Hacat细胞分别与0、2·5、5、10、20和40μg/ml的HMME孵育2h,用532nm的倍频Nd∶YAG激光以20mW/cm2的功率密度分别照射0、2·5、5、10、20min,同时设立完全空白对照组和单纯光敏剂组,24h后以MTT法检测Hacat细胞的存活率。结果Hacat细胞对HMME吸收量随着孵育浓度的增高和孵育时间的增加而增多。单独照光或以高达40μg/ml的HMME孵育对Hacat无明显杀伤(P>0·05)。在激光功率密度相同的情况下,HMME-PDT对Hacat细胞的杀伤呈孵育浓度和激光能量密度相关性。结论Hacat细胞对HMME吸收呈孵育浓度和孵育时间相关性,孵育浓度及激光能量密度是影响HMME-PDT杀伤效应非常重要的影响因素,在实验范围内的HMME-PDT能对Hacat细胞产生明显的杀伤作用。     

CT扫描对囊性肾癌的诊断价值

囊性肾细胞癌是一种较少见的特殊类型肾细胞癌,特点是肿瘤呈乳头状向囊腔突出或肿瘤位于囊壁及分隔,占肾癌的3%¹4%^[1]。由于囊性肾癌难与复杂良性囊性肾脏疾病相鉴别^[2],易被误诊。囊性肾癌可分为肾癌囊性变、单房囊性肾癌、多房囊性肾癌及单房性肾囊肿附壁癌结节4种类型^[3]。本文通过分析手术病理证实的21例囊性肾癌的CT资料,旨在提高对囊性肾癌的认知及诊断的准确率。1资料与方法     

探讨能谱CT单能量图像对计算机辅助检测系统肺栓塞检出率的影响

【摘要】目的：探讨不同水平单能量图像对计算机辅助检测系统（CAD）检出肺栓塞准确率的影响。方法：20例确诊为肺栓塞的患者均行能谱扫描模式CT肺动脉成像（CTPA）。重建40、45、50、55、60、65、70、75和80keV共9组单能量图像,然后应用CAD软件分别对各组单能量图进行分析。由两位有经验的放射科医师分析所有图像并标记出栓子,记录数量和部位,以两位医师的诊断结果作为金标准,计算各单能量图像结合CAD对栓子的检出率和假阳性率。结果：两位医师共检出120个栓子。在40~80keV的各组单能量图像上CAD对栓子的检出检出率和假阳性率分别为40.00%和0%、54.17%和2.99%、51.17%和1.59%、68.33%和5.75%、81.67%和7.55%、84.17%和12.17%、80.00%和30.77%、82.50%和36.94%、85.38%和54.42%。低keV（＜60keV）单能量水平CAD检出栓子的敏感度较低;高keV（＞65keV）单能量水平假阳性率较高。在60和65keV单能量水平时的敏感度相对较高且假阳性率相对较低。结论：能谱CT不同水平单能量图像与CAD结合能够影响栓子检出的准确性,在60~65keV单能量图像上CAD对栓子检出的敏感性较高且假阳性较低。     

西妥昔单抗对125Ⅰ粒子照射结直肠癌细胞DNA修复能力和信号传导通路的影响

目的 探讨西妥昔单抗(C225)对125Ⅰ粒子照射下结直肠癌CL187细胞DNA损伤修复和信号传导通路的影响.方法 实验分为空白对照组,100 nmol/L C225处理组,单独125Ⅰ粒子持续低剂量率照射组和C225联合125Ⅰ粒子持续低剂量率照射组.在吸收剂量达4 Gy后48 h,经细胞免疫荧光检测各组细胞中γH2AX聚集点数量以及γH2AX聚集点阳性细胞比例.提取细胞内总蛋白,Western blot检测DNA修复蛋白的变化.在吸收剂量达4 Gy后即刻提取总蛋白,Western blot分析在照射过程中C225对EGFR下游信号通路中蛋白分子的影响.结果 与单独125Ⅰ粒子持续低剂量率照射组细胞相比,C225联合125Ⅰ持续低剂量率照射组细胞内残余的γH2AX聚集点数量和γH2AX聚集点阳性的细胞比例均高(t=8.0和6.8,P＜0.05),并且细胞中DNA修复蛋白Ku70和DNA-PKcs的含量偏低(t=6.6和5.7,P＜0.05).Western blot结果显示,在125Ⅰ粒子持续低剂量率照射过程中,C225能够降低细胞内EGFR的水平(t=4.9,P＜0.05),抑制Akt的活化(t=5.5,P＜0.05).结论 在125Ⅰ放射性粒子持续低剂量率照射下,C225可以降低细胞内Ku70和DNA-PKcs的含量,并抑制Akt活化,减弱CL187细胞的DNA损伤修复能力.     

西妥昔单抗对125I粒子照射结直肠癌细胞DNA修复能力和信号传导通路的影响

目的 探讨西妥昔单抗(C225)对¹²⁵I 粒子照射下结直肠癌CL187细胞DNA损伤修复和信号传导通路的影响。方法 实验分为空白对照组,100 nmol/L C225处理组,单独¹²⁵I粒子持续低剂量率照射组和C225联合¹²⁵I粒子持续低剂量率照射组。在吸收剂量达4 Gy后48 h,经细胞免疫荧光检测各组细胞中γH2AX聚集点数量以及γH2AX聚集点阳性细胞比例。提取细胞内总蛋白,Western blot检测DNA修复蛋白的变化。在吸收剂量达4 Gy后即刻提取总蛋白,Western blot分析在照射过程中C225对EGFR下游信号通路中蛋白分子的影响。结果 与单独¹²⁵I粒子持续低剂量率照射组细胞相比,C225联合¹²⁵I持续低剂量率照射组细胞内残余的γH2AX聚集点数量和γH2AX聚集点阳性的细胞比例均高(t=8.0和6.8,P<0.05),并且细胞中DNA修复蛋白Ku70和DNA-PKcs的含量偏低(t=6.6和5.7,P<0.05)。Western blot结果显示,在¹²⁵I粒子持续低剂量率照射过程中,C225能够降低细胞内EGFR的水平(t=4.9,P<0.05),抑制Akt的活化(t=5.5,P<0.05)。结论 在¹²⁵I放射性粒子持续低剂量率照射下,C225可以降低细胞内Ku70和DNA-PKcs的含量,并抑制Akt活化,减弱CL187细胞的DNA损伤修复能力。     

高营养状态对肿瘤细胞形态和成瘤性的影响

目的 营养状态在癌症治疗中的作用一直受到广泛关注.该文旨在研究高营养状态对肿瘤细胞的影响.方法 在肿瘤细胞的培养体系中添加不同浓度的胎牛血清(FBS,5％、10％、25％、50％),以模拟不同的营养状态.培养3周后,CCK-8法测定细胞增殖;克隆形成和体内成瘤实验评价肿瘤细胞成瘤性;最后通过油红染色、流式细胞术、电镜和蛋白质印迹检测探讨可能的机制.结果 高血清浓度能促进人乳腺癌细胞系SKBR3细胞和人前列腺癌细胞系PC3M细胞的增殖,但会引起细胞空泡化,并抑制其克隆形成和成瘤能力.诱导后的PC3M细胞,自噬过程特征蛋白轻链3(LC3)Ⅱ/Ⅰ比例上调,电镜中观察到自噬小体增多,表明高浓度的血清可能通过激活自噬来抑制肿瘤细胞的成瘤性.结论高营养状态对肿瘤细胞成瘤性有明显抑制作用,有望成为新的癌症治疗策略.     

T细胞斑点实验与结核杆菌DNA检测对肠结核的诊断价值

目的 探讨结核杆菌T细胞斑点实验（T-spot-TB）与结核杆菌DNA检测在肠结核诊断中的应用价值.方法 对2009年6月～2013年4月我科行T-spot-TB与结核杆菌DNA检测的可疑肠结核患者128例进行回顾性分析,其中确诊肠结核72例,非肠结核56例.对比分析两种方法诊断肠结核的灵敏度及特异度.结果 T-spot-TB诊断肠结核灵敏度为90.3％,特异性为91.1％;结核杆菌DNA检测灵敏度为73.6％,特异性为100.0％.T-spot-TB诊断肠结核灵敏度高于DNA检测,但其特异性低于DNA检测;两种方法检测阳性率在不同病理表现的肠结核患者中无显著差异.两种方法同时检测的阳性预测值及阴性预测值均为100％.结论 T-spot-TB与结核杆菌DNA联合检测有助于提高肠结核诊断的灵敏度和特异度.     

Comparative study of the sensitivity and specificity of the zinc and acid phosphatase spot tests for the detection of seminal stains

Summary The sensitivity and specificity of a zinc spot test for the detection of semen were compared with those of an acid phosphatase detection method. As screening techniques both tests were found to be very sensitive, but the zinc test was more specific and was more reliable in older and especially in deteriorated specimens. It is concluded that the zinc spot test deserves at least the same place as the acid phosphatase test in the primary investigation of suspected semen stains and might well be the test of choice in older and poorly preserved stains.     

视频终端尺寸对儿童视疲劳的影响

目的 探讨视频终端尺寸对儿童视疲劳的影响。方法 选取儿童30名为研究对象,年龄8～13岁,所有受检者在相同条件下,每人均通过手机、平板和电视3种视频终端观看2节20 min的课程视频,比较观看后的视力、瞬目次数及Schirmer试验数据。结果 (1)观看课程视频后,3种终端双眼视力较测前(右眼5.00±0.00,左眼5.00±0.00)均有所下降(P<0.05),手机组(右眼4.90±0.05,左眼4.86±0.07)低于电视组(右眼4.98±0.02,左眼4.94±0.05),差异有统计学意义(P<0.05)。(2)观看视频35 min时,各组瞬目次数较基础值(12.10±0.88)显著增加,其中手机组(22.80±1.48)高于平板组(19.70±2.06)和电视组(17.10±1.52),差异有统计学意义(P<0.05)。(3) Schirmer试验显示,观看视频后,各组双眼泪液分泌量较基础[右眼(12.30±1.06)mm,左眼(12.30±1.49)mm]明显增加,其中手机组[右眼(20.40±1.84)mm,左眼(20.70±2.45) mm]多于平板组[...     

The effect of image display size on observer performance an assessment of variance components

RATIONALE AND OBJECTIVE: Our goal was to investigate the effect of the displayed image size on variance components during the performance of an observer performance study to detect masses on abdominal computed tomography (CT) examinations. MATERIALS AND METHODS: A previously performed receiver operating characteristic (ROC) study with eight observers to detect abdominal masses on 166 CT examinations was reanalyzed to assess variance components when comparing two similar modes with displayed image sizes varying by a factor of 2. Case, mode, and reader-related variance components were estimated for the group of eight observers and subsets of readers after excluding each of the participants. RESULTS: There was no significant difference in the average area under the ROC curves between the two modes using the two image sizes (P > .05). Reader and reader-by-case variability were substantially larger for the mode displaying enlarged images for the group and all subsets formed by excluding a single reader. Reader variability was affected by one observer who actually performed better with the enlarged images. CONCLUSION: Sequential viewing of enlarged CT images for the detection of abdominal masses did not improve performance and increased reader variability.     

Some technical parameters influencing the precision and accuracy of fragment size determination for RFLP's

Summary A comparison was carried out between 3 computer-assisted systems for the estimation of DNA fragment length: (1) the Digitab system (developed at our institute), (2) the FBI analysis system (FBI Quantico, USA) and (3) the BioImage system (Waters/Millipore, USA). Both the FBI system and the Biolmage system were found to be much more precise than the manual Digitab system. In an additional experiment, a possible influence of the field strength on the accuracy of fragment size measurement was checked. Lowering the field strength to approx. 1 V/cm led to a statistically significant increase in the measured fragment size.     

Detection of latent DNA on tape-lifts using fluorescent in situ detection

Tape-lifts can be used for the removal of a range of evidence types without damaging the substrate. In addition to loosely adhering material such as hairs and fibres, tape-lifts can be used to remove latent cellular material on clothing that had originated from the wearer’s body or mouth. Common forensic practice is to examine the entire tape-lift in a non-targeted approach. An innovative field of research uses DNA binding dyes for the detection of latent DNA. This research describes the use of these DNA binding dyes as a DNA-targeted screening tool for tape-lifts. The individual cells can be visualized allowing the relevant area of the tape to be removed for subsequent DNA typing. Full single source DNA profiles were generated that matched the expected control sample after staining tape-lifts with two different dyes. Direct amplification was undertaken from tape-lifts of samples where biological material had been deposited over 12 months previously, from which a DNA profile matching the donor was obtained. The process outlines an effective means to visualize the presence of cellular material from which STR profiles can be generated allowing a targeted approach to be performed.     

Effect of exposure parameters and voxel size on bone structure analysis in CBCT

Objective:

To evaluate the effect of exposure parameters and voxel size on bone structure analysis in dental CBCT.

Methods:

20 cylindrical bone samples underwent CBCT scanning (3D Accuitomo 170; J. Morita, Kyoto, Japan) using three combinations of tube voltage (kV) and tube current-exposure time product (mAs), corresponding with a CT dose index of 3.4 mGy: 90 kV and 62 mAs, 73 kV and 108.5 mAs, and 64 kV and 155 mAs. Images were reconstructed with a voxel size of 0.080 mm. In addition, the 90 kV scan was reconstructed at voxel sizes of 0.125, 0.160, 0.200, 0.250 and 0.300 mm. The following parameters were measured: bone surface (BS) and bone volume (BV) per total volume (TV), fractal dimension, connectivity density, anisotropy, trabecular thickness (Tb. Th.) and trabecular spacing (Tb. Sp.), structure model index (SMI), plateness, branches, junctions, branch length and triple points.

Results:

For most parameters, there was no significant effect of the kV value. For BV/TV, “90 kV” differed significantly from the other kV settings; for SMI, “64 vs 73 kV” was significant. For BS/TV, fractal dimension, connectivity density, branches, junctions and triple points values incrementally decreased at larger voxel sizes, whereas an increase was seen for Tb. Th., Tb. Sp., SMI and branch length. For anisotropy and plateness, no (or little) effect of voxel size was seen; for BV/TV, the effect was inconsistent.

Conclusions:

Most bone structure parameters are not affected by the kV if the radiation dose is constant. Parameters dealing with the trabecular structure are heavily affected by the voxel size.     

Investigative strategy for the forensic detection of sperm traces

In a retrospective study, the results from 786 samples of alleged sexual assaults during a 5-year period were evaluated. Of the samples, 758 were from female victims and 28 were from male victims. The material examined during this 5-year period consisted of 561 cotton swabs with swabs taken from the genitals, mouth, anus, or skin surface. In addition, textile products were examined 191 times, paper products 23 times, and other evidentiary materials 11 times. The acid phosphatase (acP) test was performed as a preliminary test for all samples, followed by microscopy after Baecchi staining. DNA analysis was performed on 74 samples following individual court orders. The retrospectively evaluated results from this period indicate that additional tests for the detection of sperm on textiles and paper products are dispensable after a negative acP test. This is different for genital swabs, since sperm could be found microscopically in 3% of cases with a negative acP test, and DNA analysis was also successful. However, an individual investigative strategy has to be determined for each case, as, depending on the structure of the case, the evidence of male DNA on a female victim, or on her clothes, for instance, can also have evidentiary value without microscopic proof for sperm.     

Improvement on detectability of early ischemic changes for acute stroke using nonenhanced computed tomography: Effect of matrix size

Purpose

It has recently been reported that intravenous recombinant tissue plasminogen activator improves the clinical outcome after acute stroke. Computed tomography (CT) is the standard imaging method used to determine the indication for thrombolysis. However, detection of early ischemic change often results in an increase in local radiation exposure. Therefore, the effects of decreased matrix size and use of a noise reduction filter were evaluated.

Materials and methods

The low contrast resolution was compared for different matrix sizes and imaging filters using a contrast-detail phantom. In addition, early ischemic change in clinical images with matrix sizes of 256 × 256 and 128 × 128 processed using three imaging filters (Gaussian, smoothing, and unsharp mask) from 11 patients within 3 h of stroke onset was evaluated by seven radiologists in a blind manner.

Results

The use of images with a matrix size of 256 × 256 and processed with the Gaussian filter increased the detection of early signs of acute stroke.

Conclusions

This study was performed to determine whether the converted matrix size and use of imaging filters could improve the detectability of early ischemic change on CT images in acute stroke. To reduce the dose of radiation exposure for patients, it was effective to use an optimal noise reduction filter and reasonable matrix size. In particular, changing the matrix size to 256 × 256 was the most effective for detection of early ischemic change in examinations using clinical images.