Over-expression of SK2 channel in PVN reduces renal sympathetic nerve activity in chronic heart failure rats

AIM：To investigate the effect of over-expression of small-conductance calcium-activated potassium channel subtype 2 (SK2) in the paraventricular nucleus (PVN) of hypothalamus on heart rate(HR), mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) of the rats with chronic heart failure (CHF). METHODS：Adenovirus vector encoding SK2 (pDC316-mCMV-EGFP-rKCNN2) was constructed.The CHF model of the male Sprague Dawley (SD) rats was established by the ligation of anterior descending coronary artery. Echocardiogram was used at the 6th week after the operation to identify the CHF model. Adenovirus vector encoding SK2 (pDC316-mCMV-EGFP-rKCNN2) or control adenovirus vector (pDC316-mCMV-EGFP) were transfected into the PVN in vivo. The cardiac function was monitored by echocardiogram. The expression of SK2 at mRNA and protein levels was determined by RT-PCR, Western blotting and immunofluorescence. The HR, MAP and RSNA were measured by PowerLab 8/30 in anesthetized rats with bilateral PVN microinjection of SK channel blocker apamin. RESULTS：Treatment with pDC316-mCMV-EGFP-rKCNN2 significantly decreased the renal sympathetic nerve activity in the rat with CHF. Injection of pDC316-mCMV-EGFP did not change the renal sympathetic nerve activity in the rats in sham group. CONCLUSION：The expression and function of SK channels in PVN in the heart failure rats were decreased, suggesting a reduced negative regulation of sympathetic activity in central neural system. Increased expression of SK2 in the PVN leads to a reduction in sympathetic outflow under the condition of CHF, which may provide a new target for the treatment of heart failure.     

Alterations in enzyme activities in vital organs of triploid female catfish Heteropneustes fossilis (Bloch)

Triploid Heteropneustes fossilis (Bloch) showed sterility and higher growth potential than the normal diploid fish. Activities of some metabolic enzymes such as cytosolic NADP-malate dehydrogenase (NADP-MDH), mitochondrial NAD-malate dehydrogenase (NAD-MDH) and glutamate pyruvate transaminase (GPT) were evaluated in liver, brain and kidney along with glucose-6-phosphate dehydrogenase (G-6-P D) in ovary of female triploid catfish. Activities of these enzymes showed distinct seasonal periodicity, mostly with highest activities in prespawning and spawning periods, in both diploid and triploid catfish but differed in magnitude. In triploid liver, GPT showed higher activity than the diploid counterpart in prespawning and spawning periods. On the contrary, mitochondrial NAD-MDH and cytosolic NADP-MDH in this organ showed a consistent lower activity than the diploid in all stages or in some stages of reproductive cycle respectively. Interestingly, none of the enzymes in brain and kidney of triploid female catfish showed significant changes in comparison to the diploid counterpart. The triploid ovary maintained a significantly lower level of G-6-P D activity throughout the resting, preparatory and pre-spawning periods compared to the diploid ovary. Lower level of malic enzymes (NAD-MDH and NADP-MDH) in liver and G-6-P D in ovary are in close synchrony with lower level of estradiol-17β in plasma of female triploids as found in earlier study.     

欧洲天然气管道发展特点及事故原因

根据对欧洲天然气管道事故数据组织EGIG的输气管道事故报告的分析和总结,在汲取国外天然气管道事故教训和学习国外天然气管道建设经验的基础上,对国内天然气管道的发展提出了建议。采用事故统计分析的方法,并结合图表,分析了天然气管道总体和局部范围内的事故变化特点和趋势,总结出5种基本原因导致天然气管道事故的失效频率。认为在通过优化管道建设提高本质安全的同时,还应通过管道泄漏监控技术及时发现管道泄漏情况,通过安全预警技术及时预判可能发生的泄漏事故。此外,针对国内天然气管道建设及安全运行管理等方面提出了5条建议,可为国内天然气管道的发展提供支持。（图4,表3,参8）     

中国石油油气管道失效数据管理问题及对策

中国石油对于重大事故的分析与经验分享较为重视,但缺乏对于较轻微事故或事件的分析、发布和共享,不利于发现事故／事件规律,难以保障油气管道等生产设施的本质安全。通过分析国内外油气管道失效数据库的建立与使用情况,阐述了建立、维护油气管道失效数据库的重要性,总结了当前中国石油油气管道失效数据库存在的问题,包括管理标准缺失,缺乏体系约束与政策激励。结合美国、加拿大、欧洲、英国等失效数据库的失效定义、上报流程以及国内管道行业失效信息收集的实际情况,给出了中国石油油气管道失效数据库的进一步推广建议。     

高压燃气管道第三方破坏失效概率计算

介绍了对城镇高压燃气管段进行定量风险评价的重要性,分析认为城镇燃气管道失效的主要原因为第三方破坏。为计算城市高压燃气管道的第三方破坏失效概率,提出了基于修正因子的失效概率计算法和通用失效概率主观修正法两种失效概率计算模型,并针对实际城市高压燃气管道,分别计算得出两个失效概率值,最终取较大值作为定量风险评价的失效概率值。采用两种模型计算管道第三方破坏失效概率能够起到相互比较、相互验证的作用,使计算结果更加准确可靠。该方法可为我国城镇燃气管道定量风险评价研究提供参考。（图1,表4,参15）     

110kV终端变电站接入系统过渡方案分析

指出了110kV终端变电站原接入系统方案由于各种原因无法实施,提出了临时过渡方案及要求,对两种接入系统过渡方案进行了分析,分别从线路N一1分析、系统结构对比、经济角度和远景适应性等4个方面进行了探讨,确定了终端变电站系统过渡方案。     

曲美他嗪治疗冠心病心力衰竭近期疗效评价

目的探讨曲美他嗪治疗冠心病心力衰竭的临床疗效．方法根据治疗方案将114例冠心病心力衰竭患者分为两组,57例患者实施常规治疗为对照组,57例患者在常规治疗基础上加用曲美他嗪治疗为观察组,疗程6个月,比较两组患者的临床指标改变情况、治疗效果、药物不良反应情况．结果治疗后,两组患者左室射血分数、心输出量、左室短轴缩短率、6min步行距离、每搏输出量均显著增加,两组患者左室舒张末期内径、左室收缩末期内径、血浆B型钠尿肽均显著减小;观察组患者左室射血分数、心输出量、左室短轴缩短率、6min步行距离、每搏输出量均明显大于对照组;观察组患者左室舒张末期内径、左室收缩末期内径、血浆B型钠尿肽均明显小于对照组;观察组患者治疗总有效率明显高于对照组,差异均具有统计学意义（P〈0．05）;观察组患者药物不良反应发生率高于对照组,但差异无统计学意义（P〉0．05）．结论曲美他嗪是治疗冠心病心力衰竭的有效药物,可明显改善患者的临床指标,提高治愈率,药物不良反应少,且安全性高,值得临床推广使用．     

电子液压制动系统的安全设计与匹配分析

针对电子液压制动系统的设计缺乏理论指导的问题,在建立电子液压制动系统数学模型的基础上,提出基于安全特性的电子液压制动系统匹配设计方法;通过试验验证所建立的数学模型的有效性,分析电子液压制动系统在普通制动和硬件失效下的制动性能。研究表明:基于安全特性考虑应保证在电机泵失效的情况下蓄能器仍能使车辆完成数次大强度制动;而电机泵的设计应兼顾期望的充液时间以及蓄能器失效下的保持车辆制动性能;备用制动回路作为电子液压制动系统系统的硬件冗余,要求其在蓄能器和电机泵均失效的情况下提供一定的制动能力。仿真分析表明:基于安全特性的电子液压制动系统匹配设计方法能够在正常情况和硬件失效的情况下均能保证车辆的制动安全性。     

微耕机的日常维护和故障排除

微耕机的机手只要做到注意日常维护和了解常见故障与排除方法,就能达到充分发挥该机的最大功效,延长该机的使用寿命,降低保养费用和使用成本。