Submitochondrial distribution of three key steroidogenic proteins (steroidogenic acute regulatory protein and cytochrome p450scc and 3beta-hydroxysteroid dehydrogenase isomerase enzymes) upon stimulation by intracellular calcium in adrenal glomerulosa cells

In adrenal glomerulosa cells, angiotensin II (Ang II) and potassium stimulate aldosterone synthesis through activation of the calcium messenger system. The rate-limiting step in steroidogenesis is the transfer of cholesterol to the inner mitochondrial membrane. This transfer is believed to depend upon the presence of the steroidogenic acute regulatory (StAR) protein. The aim of this study was 1) to examine the effect of changes in cytosolic free calcium concentration and of Ang II on intramitochondrial cholesterol and 2) to study the distribution of StAR protein in submitochondrial fractions during activation by Ca2+ and Ang II. To this end, freshly prepared bovine zona glomerulosa cells were submitted to a high cytosolic Ca2+ clamp (600 nM) or stimulated with Ang II (10 nM) for 2 h. Mitochondria were isolated and subfractionated into outer membranes, inner membranes (IM), and contact sites (CS). Stimulation of intact cells with Ca2+ or Ang II led to a marked, cycloheximide-sensitive increase in cholesterol in CS (to 143 +/- 3. 2 and 151.1 +/- 18.1% of controls, respectively) and in IM (to 119 +/- 5.1 and 124.5 +/- 6.5% of controls, respectively). Western blot analysis revealed a cycloheximide-sensitive increase in StAR protein in mitochondrial extracts of Ca2+-clamped glomerulosa cells (to 159 +/- 23% of controls). In submitochondrial fractions, there was a selective accumulation of StAR protein in IM following stimulation with Ca2+ (228 +/- 50%). Similarly, Ang II increased StAR protein in IM, and this effect was prevented by cycloheximide. In contrast, neither Ca2+ nor Ang II had any effect on the submitochondrial distribution of cytochrome P450scc and 3beta-hydroxysteroid dehydrogenase isomerase. The intramitochondrial presence of the latter enzyme was further confirmed by immunogold staining in rat adrenal fasciculata cells and by immunoblot analysis in MA-10 mouse testicular Leydig cells. These findings demonstrate that under acute stimulation with Ca2+-mobilizing agents, newly synthesized StAR protein accumulates in IM after transiting through CS. Moreover, our results suggest that the import of StAR protein into IM may be associated with cholesterol transfer, thus promoting precursor supply to the two first enzymes of the steroidogenic cascade within the mitochondria and thereby activating mineralocorticoid synthesis.     

特低渗透油层含油饱和度的一种校正方法

松辽盆地北部扶杨油层属特低渗透油层，即使采用油基泥浆取心或密闭取心样品，束缚水饱和度也难以测准。蒸馏法试验表明，若试验温度低，则束缚水蒸发不彻底，实测含水饱和度偏低；若试验温度高，则容易造成岩样粘土矿物晶间水脱水，实测含水饱和度偏高，影响了储量计算精度。为搞清特低渗透油层流体蒸发特征，开展了蒸发率试验，试验过程是：将岩样洗油后重新饱和水，再在与蒸馏法试验相同的试验条件下测定蒸发的水量。试验结果表明，有效孔隙度越小，蒸发率越低。由于两个试验过程的蒸发率近似相等，用蒸发率试验可以模拟蒸馏法试验，由此推导出束缚水饱和度计算公式。应用该公式对榆树林油田进行测算，校正前后原始含油饱和度相差１２％以上，储量相差２０×１０６ｔ以上。图２（郭海莉摘）     

光学系统中离轴性公差的计算机设计

运用不共轴光学系统的光路计算和象质评价理论，通过共轴光学系统中光学表面，光学元件，部件的小位移和微倾斜，对切比雪夫综合象质函数计算相应的有关限差分，以掌握各种离轴性误差对象质的危害程度，再按多元函数的极值理论和适应度性优化技术自动妥共轴光学系统中各种轴性公差，并进行反馈和非线性处理；达到公差的最优化分配。     

The role of glutathione in dopaminergic neuronal survival

An increased production of reactive oxygen species is thought to be critical to the pathogenesis of Parkinson's disease. At autopsy, patients with either presymptomatic or symptomatic Parkinson's disease have a decreased level of glutathione in the substantia nigra pars compacta. This change represents the earliest index of oxidative stress in Parkinson's disease discovered to this point. This study compares the sensitivity of dopaminergic and nondopaminergic neurons in dissociated mesencephalic cultures to the depletion of glutathione. We have found that dopaminergic neurons are more resistant to the toxicity of glutathione depletion than nondopaminergic neurons. The possibility that dopaminergic neurons have a higher baseline glutathione level than nondopaminergic neurons is suggested by measurements of levels of cellular glutathione in a parallel system of immortalized embryonic dopaminergic and nondopaminergic cell lines. We also examined the role of glutathione in 1-methyl-4-phenylpyridinium toxicity. Decreasing the glutathione level of dopaminergic neurons potentiates their susceptibility to 1-methyl-4-phenylpyridinium toxicity, although 1-methyl-4-phenylpyridinium does not deplete glutathione from primary mesencephalic cultures. Our data suggest that although a decreased glutathione content is not likely to be the sole cause of dopaminergic neuronal loss in Parkinson's disease, decreased glutathione content may act in conjunction with other factors such as 1-methyl-4-phenylpyridinium to cause the selective death of dopaminergic neurons.     

浅谈托辊的开发与实践

本钢１７００连轧机应用的托辊原由外企业制作，为了减少公司资金外流，公司技术人员和工人结合现有的生产条件，先后攻克了辊身铸造和加工，托辊装配等工艺方面的难关，研制成功了合格的产品，年创经济效益８０万元。     

Digital Connectivity and Extended Well-Composed Sets for Gray Images

In this paper, we propose a new definition of digital connectivity for gray images on a 2D space for arbitrary grid systems. We extend a digital version of the Jordan curve theorem and its converse proved earlier by Rosenfeld for the rectangular grid system. We also extend in two directions the concept of well-composed sets introduced by Lateckiet al.(1995,Comput. Vision Image Understanding61,70–83). First, we extend the definition of well-composed sets from the quadratic grid system to an arbitrary grid system. Then, by using the concept of parameter-dependent connected components introduced by us in a previous work, we allow the pixels in a connected component of a well-composed set to have different gray values so that the connectivity of connected components accommodates a wider meaning.     

Role of hepatic resection in surgery for bilateral intrahepatic stones

The effect of phenylephrine-induced reflex parasympathetic stimulation on QT interval and its dispersion was studied in 16 healthy subjects with a history of paroxysmal supraventricular tachycardia, both during sinus rhythm and during atrial pacing. Results demonstrate that rapid reflex parasympathetic stimulation does not influence QT interval duration or QT dispersion, and also emphasize the inappropriateness of Bazett's formula, the need for comparison of QT intervals during identical heart rates, and the importance of analyzing all 12 leads of a standard electrocardiogram when assessing the effects of various interventions on the QT interval.     

水力喷砂割缝增产增注技术的作用原理及展望

本文对从俄罗斯引进的水力喷砂割缝技术的发展过程、工作原理及该技术在大庆油田的试验情况做了详细的阐述。并对它的改进及其将来的推广与发展前景做了展望。     

鲁布革水电厂计算机监控系统的更新改造

鲁布革水电厂原Ｒ３０计算机监控系统更新改造过程中，重点研究了与原西门子ＲＴＵ的数据交换，机组功率调节和线路定功率调节的实现有关问题，在对３号机组计算机监控系统改造试验的基础上，成功地实现了计算机监控系统的整体改造，改造后采用的国产ＮＡＲＩＳＳＪ－３０００计算机监控系统实用可靠，功能完善，配置灵活，具有国际，国内领先水平。     

认真总结经验继续做好大坝安全定检工作

我国电力系统的水电站大坝，大多数为高坝大库，确保这些大坝的安全，事关国民经济的发展和社会稳定的大局。因此，加强水电站大坝安全管理工作，是摆在各级电力主管部门面前的一项重大社会责任。１９８５年大坝安全监察中心（以下简称“大坝中心”）成立后，依法行使大坝安全监察职能，在国家电力主管部门的直接领导和各大坝安全责任单位的支持下，做了大量开创性工作。水电站大坝安全定期检查就是其中的一项重要内容。首轮定检从１９８７年古田溪一级开始试点到１９９８年底为止，已圆满完成９６座水电站大坝的定检工作。通过首轮定检，对…