Effects of Dryk1A,ASF and alternative splicing of CaMKⅡδ on myocardial hypertrophy in renovascular hypertensive rats

AIM: To investigate the role of dual-specificity tyrosine phosporylation-regulated kinase 1A (Dyrk1A)-alternative splicing factor (ASF)-calcium/calmodulin-dependent protein kinase Ⅱδ (CaMK Ⅱδ) pathway in the progression of myocardial hypertrophy in renovascular hypertensive rats. METHODS: The renovascular hypertension was induced by two-kidney one-clip (2K1C) method. The changes of blood pressure and myocardial hypertrophy were measured. The techniques of RT-PCR and Western blotting were used to detect CaMKⅡδ alternative splicing and the protein expression of Dyrk1A and ASF, respectively. RESULTS: Eight weeks after operation, systolic blood pressure (SBP) and diastolic blood pressure (DBP) in 2K1C rats increased (P<0.05). The increases in left ventricular weight (LVW), the ratio of LVW to body weight (BW) and the area of myocardial cells indicated that the hypertensive rats developed significant cardiac hypertrophy. The protein expression of Dyrk1A and mRNA expression of CaMKⅡδA and δB were significantly increased, while the protein expression of ASF and mRNA expression of CaMKⅡδC were decreased compared with sham-operated control rats (P<0.05). Treatment with Dryk1A inhibitor epigallocatechin gallate (EGCG) or harmine effectively attenuated cardiac hypertrophy and reversed the changes in the protein expression of Dyrk1A, ASF and alternative splicing of CaMKⅡδ (all P<0.05). CONCLUSION: Dyrk1A-ASF-CaMKⅡδ pathway plays a role in the development of myocardial hypertrophy in renovascular hypertensive rats.     

Neuroprotective effect of L-serine on rats with permanent middle cerebral artery occlusion

AIM: To investigate the neuroprotective effect, therapeutic dosage and time window of L-serine against permanent cerebral injury in rats. METHODS: Permanent middle cerebral artery occlusion (pMCAO) was induced in the rats to determine the efficacy of L-serine (ip) by neurological evaluation, TTC staining and Nissl staining.L-serine was used at different doses (56 mg/kg, 168 mg/kg and 504 mg/kg) and for different time periods (1 h, 3 h, 6 h, 12 h and 24 h after pMCAO). Aminooxyacetic acid (AOAA), an inhibitor of serine racemase, was used to alter the efficacy of L-serine. Laser Doppler perfusion monitor was used to observe the regional cerebral blood flow (rCBF) in the ischemic cerebral cortex under the condition with or without L-serine treatment. RESULTS: Treatment with L-serine at doses of 168 mg/kg and 504 mg/kg at time point of 3 h after pMCAO greatly decreased the neurological deficit score and infarct volume,and attenuated the loss of hippocampal CA1 neuronal cells. In the observation of therapeutic time window, L-serine displayed a significant neuroprotective effect if used within 6 h after pMCAO, but did not exert any notable effect if used over 12 h after pMCAO. AOAA hardly changed the effect of L-serine. L-serine treatment notably raised rCBF in the area of ischemic cerebral cortex when it was injected 30 min after pMCAO. However, strychnine, an antagonist of strychnine-sensitive glycine receptor, did not alter this effect of L-serine. CONCLUSION: L-serine has neuroprotective effect on permanent ischemic brain injury in rats if administered early and sufficiently by augmentation of rCBF in the ischemic cerebral cortex.     

大学本科生学习创新能力培养和优良学风建设

学习创新能力,是创新精神和实践能力的一个重要组成部分。优良学风建设一直是高校的重要工作。针对高校学风存在的主要问题,阐述了学习创新能力的内涵及其重要意义,培养大学本科生学习创新能力的方法与途径,以及通过对大学本科生学习创新能力的培养有助于促进优良学风建设的形成。     

钙调素基因启动子序列多态性对京海黄鸡产蛋性状和蛋壳性状的遗传效应

本试验旨在分析钙调素(Calmodulin,CAM)基因启动子区域碱基多态性与京海黄鸡产蛋性状和鸡蛋蛋壳质量性状间的关系。采用PCR-SSCP法检测京海黄鸡CAM基因启动子区域碱基多态性。结果表明:京海黄鸡CAM基因启动子区域有3个SNPs(G326A、A327G、C366T),PCR扩增产物SSCP出现6种基因型:AA、AB、AC、BB、BC和CC。AA基因型个体的300日龄产蛋数和66周龄产蛋数显著高于BB型个体(P<0.05)。AA型个体的蛋壳强度和蛋壳重显著小于AB、BB、AC和BC型个体(P<0.05)。CAM基因座对京海黄鸡300日龄蛋重、蛋型指数、蛋壳强度和壳重百分率的主效应指数(MEI)均大于3%。初步推断CAM基因座可能是影响京海黄鸡产蛋数和蛋壳质量性状重要候选基因。     

基于热流固耦合的LNG低温潜液泵转子部件模态分析

利用UG对LNG潜液泵进行三维造型,再以ANSYS Workbench为平台,对LNG低温潜液泵的转子部件进行热流固耦合计算,得出流场对固体结构部分的热流固耦合力,把热流固耦合力作为预应力添加到转子部件上.分别对转子部件进行无预应力和有预应力作用下的模态分析,基于计算结果,提取了转子部件的前10阶模态,并把2种情况下的模态进行比较.结果表明:除了七阶、八阶振动为轴的摆动,其他各阶的振动变形都表现在叶轮上;添加预应力之后,转子部件的各阶振型没有发生变化,但每一阶的固有频率都有轻微的变化,预应力对转子部件各阶固有频率的影响很小;九阶和十阶的固有频率比较接近泵的3倍叶频,有发生共振的危险,需要对转子部件进行优化设计,使前3倍叶频都能远离各阶固有频率,从而避免泵在运行过程中发生共振;在预应力的作用下,转子部件的各阶振幅也都有小幅度的变化.     

离心泵作透平固液两相流动及磨损的数值模拟

为研究离心泵作透平内部固液两相流动特性,基于Euler-Lagrange模型,应用ANSYS CFX软件对一比转数为82的离心泵作透平进行数值计算,分别模拟颗粒直径为0.1,0.3,0.5 mm及初始体积分数为5%,10%,15%的9组不同工况,以揭示介质中固体颗粒对离心泵作透平运行的影响.计算结果表明:固体颗粒主要分布在叶片吸力面头部、前盖板壁面附近以及蜗壳尾部区域;当固体颗粒质量分数不变时,随着粒径的增大,叶片表面固相体积分数增大,叶片吸力面轮缘处出现了大量颗粒堆积,透平的扬程和功率上升,效率有所下降;当颗粒直径不变时,随着固体颗粒质量分数的增大,固体颗粒在叶轮流道内的分布出现向轮毂处延伸的趋势,堆积区域面积增大,透平的扬程和功率上升,效率变化不大.该研究扩展了液力透平设计方法,可为离心泵作透平设计提供一定的参考.     

山药不同处理方式的保存效果

运用涂抹草木灰、石蜡及自然干燥、吹风机干燥等方法对山药茎段切口进行处理,研究不同切口处理方式对山药外观及品质的影响;比较不同浓度壳聚糖与15%柠檬酸组合对切片的保鲜影响,进行山药茎段切口处理方法及切片表面处理方法的筛选。结果表明:室温下涂抹草木灰对鲜切山药茎段的贮藏效果最好;4℃条件下,15%柠檬酸+0.5%壳聚糖处理对山药切片的保鲜效果最好。     

基于虚拟样机技术的蛇行试验仿真分析

利用MSC.ADAMS/CAR建立了前后悬架、转向、动力等子系统的仿真模型,并组装成整车虚拟样机系统模型。通过驾驶员控制文件DCF和驾驶员控制数据文件DCD的配合使用,设置驾驶员-汽车-外界环境闭环系统的蛇行路径,最后按照国家标准对整车进行蛇行试验仿真,并对分析结果进行评价。     

基于VAR模型的蛋鸡产蛋性能及其影响因素分析

蛋鸡产蛋性能指标包括产蛋率和合格鸡蛋的平均蛋重,该性能受蛋鸡个体、饲养管理、养殖环境、疫病等诸多因素影响.研究各因素对产蛋性能的影响及其时延效果对蛋鸡养殖过程管理十分重要.将蛋鸡的采食、饮水、环境温度和湿度作为主要影响因素,建立向量自回归(vector auto-regressive,VAR)模型,实现了产蛋率的中短期...     

国内残膜回收机脱膜装置的研究现状

介绍了残膜在农业生产中危害及机械化回收残膜的优势,论述了我国残膜回收机的分类和特点,并指出脱膜装置作为残膜回收机核心部件的重要性。针对国内残膜回收机的研究现状,介绍几种不同结构形式的脱膜装置,并对其在实际作业中所存在的问题进行了分析,总结优缺点,为以后残膜回收机脱膜装置的机构参数优化提供参考。