科创中国

目的 探讨精液处理前后精子DNA损伤程度的改变及与过氧化氢(H2O2)、过氧化氢酶(CTA)之间的关系.方法 接受体外受精-胚胎移植(IVF-ET)助孕且进行常规IVF受精的夫妇75例,男性患者作为研究对象.在IVF当日精液采集后0.5h留取精液标本1ml,剩余精液以Pure Sperm梯度离心法进行精液处理,于处理后将精子浓度调整为10*106/ml,留取标本1ml.采用精子吖啶橙染色方法测定精子DNA损伤,H2O2及CTA含量测定采用分光光度比色测定法.结果 精液处理后的精子DNA损伤程度与处理前相比明显降低(P<0.05),H2O2浓度亦显著降低(P<0.05),CTA浓度变化不显著.精子DNA损伤率在精液处理前及处理后均与H2O2浓度呈正相关(r值在处理前后分别为0.684和0.753,P<0.05),精子DNA损伤率在精液处理前与CTA浓度呈负相关(r=-0.476,P<0.05),而处理后两者无相关性(r=-0.087,P>0.05).结论 高过氧化物水平可导致精子DNA损伤,精液优化处理可以使精子脱离高活性氧的环境,并且减少DNA损伤的精子.

Lightweight design requires an accurate life prediction for structures and components under service loading histories. However, predicted life with the existing methods seems too conservative in some cases, leading to a heavy structure. Because these methods are established on the basis that load cycles would only cause fatigue damage, ignore the strengthening effect of loads. Based on Palmgren-Miner Rule(PMR), this paper introduces a new method for fatigue life prediction under service loadings by taking into account the strengthening effect of loads below the fatigue limit. In this method, the service loadings are classified into three categories: damaging load, strengthening load and none-effect load, and the process for fatigue life prediction is divided into two stages: stage I and stage II, according to the best strengthening number of cycles. During stage I, fatigue damage is calculated considering both the strengthening and damaging effect of load cycles. While during stage II, only the damaging effect is considered. To validate this method, fatigue lives of automobile half shaft and torsion beam rear axle are calculated based on the new method and traditional methods, such as PMR and Modified Miner Rule(MMR), and fatigue tests of the two components are conducted under service loading histories. The tests results show that the percentage errors of the predicted life with the new method to mean life of tests for the two components are –3.78% and –1.76% separately, much lesser than that with PMR and MMR. By considering the strengthening effect of loads below the fatigue limit, the new method can significantly improve the accuracy for fatigue life prediction. Thus lightweight design can be fully realized in the design stage.

目的 研究围生期营养不良对仔鼠学习记忆的影响,探讨其可能的机制.方法 怀孕14 d的SD大鼠分为实验组(半量饮食组)与对照组(正常饮食组),至哺乳期结束(仔鼠出生21 d)后实验组和对照组的仔鼠均正常饮食.测量仔鼠出生时和成年时的体质量.采用Morris水迷宫测试仔鼠的学习、记忆功能.免疫组化检测DNA氧化损伤(8-OhdG)和Western blot检测DNA氧化损伤修复(OGG1)指标.结果 实验组仔鼠出生和成年后体质量均小于对照组[(4.66±0.28) g vs (6.59±0.16)g,(187.66 ±22.67)g vs(279.50±18.73)g,P<0.01];Morris水迷宫实验中,空间探索实验实验组较对照组潜伏时间长[(37.21 ±4.93) svs (16.41 ±5.21)s,P<0.05],穿越平台次数较少[(6.57 ±1.22)vs(13.12 ±2.34),P<0.05],跨越目标象限时间占整个游泳的时间百分率低[(32.75±4.58)%vs (60.31±6.74)%,P<0.01],Morris水迷宫实验表明实验组学习记忆功能均比对照组下降;8-OHdG的表达在幼年期(22 d)和成年期(90 d)实验组均比较高,与对照组相比具有统计学意义[(18.01±0.05)vs(5.77 ±0.03),(21.15±0.10)vs(10.81 ±0.08),P<0.05];OGG1的表达在幼年期(22 d)和成年期(90 d)实验组均比较低,与对照组相比差异具有统计学意义[(0.32±0.08)vs(0.81±0.06),(1.57 ±0.10) vs (2.78 ±0.53),P<0.05].结论 围生期营养不良对仔鼠成年期的学习记忆功能产生影响,其机制可能与DNA氧化损伤、修复调节的障碍有关.

为探究蚜虫共生菌基因组DNA的提取方案,以桃蚜为试验材料,比较了目前较为常用的4种蚜虫基因组DNA提取方法,从DNA纯度、完整性、PCR扩增效率及稳定性等方面进行了比较和评价,并通过调整蛋白酶K用量和水浴温度及时间对STE法进行了优化.结果表明,4种方法提取的蚜虫共生菌基因组DNA均可用于共生菌的PCR扩增检测;CTAB法和SDS法提取的DNA纯度较高,条带较完整,稳定性相对较高,不易降解,而STE法和PCR缓冲液法操作简便,适于快速提取单头蚜虫共生菌的基因组DNA,但纯度相对较低;可根据试验条件和要求进行选择.STE法优化条件为:用30μL STE缓冲液将蚜虫匀浆,加入1.5μL 20 mg/m L蛋白酶K,于56℃水浴1.5 h;再加入0.1μL 10 mg/L RNA酶,于37℃培养1 h,95℃下处理5 min,5 000 r/min离心3 min,将提取到的DNA于-20℃保存或直接用于PCR扩增.优化后的STE法可作为提取蚜虫共生菌基因组DNA经济而快捷有效的方法.

总结了近年来在鱼类物种鉴定中常用的DNA序列分析、DNA指纹技术、物种特异性聚合酶链式反应和实时荧光PCR技术等DNA检测方法,同时对各类方法的特点和局限性进行了分析.

Many researches on drilling force and temperature have been done with the aim to reduce the labour intensiveness of surgery, avoid unnecessary damage and improve drilling quality. However, there has not been a systematic study of mid- and high-speed drilling under dry and physiological conditions(injection of saline). Furthermore, there is no consensus on optimal drilling parameters. To study these parameters under dry and physiological drilling conditions, pig humerus bones are drilled with medical twist drills operated using a wide range of drilling speeds and feed rates. Drilling force and temperature are measured using a YDZ-II01 W dynamometer and a NEC TVS-500 EX thermal infrared imager, respectively, to evaluate internal bone damage. To evaluate drilling quality, bone debris and hole morphology are observed by SEM(scanning electron microscopy). Changes in drilling force and temperature give similar results during drilling such that the value of each parameter peaks just before the drill penetrates through the osteon of the compact bone into the trabeculae of the spongy bone. Drilling temperatures under physiological conditions are much lower than those observed under dry conditions, while a larger drilling force occurs under physiological conditions than dry conditions. Drilling speed and feed rate have a significant influence on drilling force, temperature, bone debris and hole morphology. The investigation of the effect of drilling force and temperature on internal bone damage reveals that a drilling speed of 4500 r/min and a feed rate of 50 mm/min are recommended for bone drilling under physiological conditions. Drilling quality peaks under these optimal parameter conditions. This paper proposes the optimal drilling parameters under mid- and high-speed surgical drilling, considering internal bone damage and drilling quality, which can be looked as a reference for surgeons performing orthopedic operations.

线粒体是真核细胞内进行氧化磷酸化和三磷酸腺苷(adenosine triphosphate,ATP)合成的细胞器,为细胞活动提供能量,有"细胞动力工厂"之称.此外,线粒体还是细胞内活性氧(reactive oxygen species,ROS)产生的主要场所,并能启动和执行细胞的凋亡[1].线粒体由核基因和线粒体基因组共同编码,其DNA(mitochondrial DNA,mtDNA)和(或)核DNA(nuclear DNA,nDNA)的遗传缺陷均可引起线粒体功能障碍而导致疾病发生.1线粒体DNA

在计算DNA的过程中,所面临的一大难点就是以表达和传递信息为主要目的编码问题,计算DNA的可靠性在一定程度上取决于编码设计的有效性.首先从遗传密码表、用户DNA配置以及文件DNA编码三方面对编码加以阐述,从DNA操作算子以及访问控制的自然计算过程两方面对算法加以介绍.

miRNA的异常表达与肿瘤的发生、发展密切相关,但miRNA的表达调控机制目前尚不清楚。有研究提示,在肿瘤细胞中DNA 甲基化异常会引起 miRNA 的表达改变,即DNA甲基化程度的改变将促进或抑制miRNA的表达,从而抑制或促进肿瘤的发生、发展。因此,DNA甲基化对miRNA的调控作用已成为肿瘤相关研究领域中的“新大陆”。该文就DNA甲基化调控miRNA的表达并参与人类肿瘤发生、发展的有关研究进展作一综述。

目的 探讨吸烟对男性不育患者精子DNA完整性及精子形态的影响.方法 132例男性不育患者根据烟龄分为2组:A组烟龄1~5年;B组烟龄大于5年.正常对照组为100例非吸烟已生育健康男性.对其进行精子DNA完整性检测及精子形态学分析.结果 A组精子DNA碎片指数(DFI)和精子畸形率与正常对照组比较差异有显著性(P<0.05),而B组精子DNA碎片指数和精子畸形率与正常对照组比较差异有非常显著性(P<0.01).结论 长期吸烟可能会损伤男性精子DNA及影响精子形态,是引起男性不育的原因之一.