Evidence for the involvement of protein kinase C isoforms in alpha-1 adrenergic activation of phospholipase A2 in FRTL-5 thyroid cells

BACKGROUND: FRTL-5 thyroid cells are a cell line extensively used for the investigation of thyroid functions. Activation of alpha-1 adrenergic receptors stimulates both arachidonic acid (AA) release and cytosolic Ca2+ increase in this cell line. Cytosolic Ca2+ and arachidonic acid are known to be important second messengers regulating a variety of thyroid functions. The generation of these messengers is regulated primarily by two different types of phospholipases, phospholipase C (PLC) and phospholipase A2 (PLA2). METHODS: Norepinephrine (NE, 10 mumol/L) was used as an alpha-1 adrenergic activator, and cytosolic-free Ca2+ concentration ([Ca2+]i) was determined using the fluorescent dye indo-1. Arachidonic acid release was measured as an indicator of PLA2 activation, and protein kinase C (PKC) activity determination and isoforms identification were performed using commercial kits. RESULTS: Norepinephrine increased [Ca2+]i and AA release. Prevention of NE-induced cytosolic Ca2+ influx, either by removal of extracellular Ca2+ or by use of Ca2+ channel blockers, NiCl2 or CoCl2, inhibited AA generation entirely. Inhibition of NE-induced increase in [Ca2+]i by the Ca2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), also significantly suppressed NE-induced AA release. Inhibition of PKC activity by PKC inhibitors (H-7 or staurosporine) or downregulation induced by prolonged treatment with phorbol 12-myristate 13-acetate (PMA) or thyleametoxin (TX) significantly blocked the NE-induced AA release, which indicates PKC is involved in mediating NE-induced AA release. Protein kinase C activity measurement indicated that NE induced an activation of PKC in 5 minutes. To further characterize the role of PKC or Ca2+ in regulation of AA release, we identified PKC isoforms by immunoblotting with specific antibodies against 8 different Protein kinase C isoforms. PKC-alpha, -beta I, -beta II, -gamma, delta, -epsilon, -zeta, and -eta isoforms were identified. Norepinephrine induced translocation of PKC-alpha, -beta I, -beta II, -gamma, -delta, and -epsilon isoforms but not -zeta and -eta from cytosol to membrane. Chelation of intracellular Ca2+, prevention of Ca2+ influx, or prolonged treatment with thymeleatoxin (TX) completely blocked the NE-induced translocation of PKC-alpha. CONCLUSIONS: These results, taken together with data obtained from AA experiments, suggest that PKC plays a critical role in alpha-1 adrenergic receptor mediated PLA2 activation and subsequent AA release. Extracellular Ca2+ influx is a prerequisite for both PKC-alpha translocation and AA release. Whether Ca2+ acts directly upon the PLA2, or via PKC-alpha, to regulate AA generation is an intriguing question that remains to be clarified.     

Ni对球墨铸铁热处理的影响

采用电子探针，图象分析仪、差质变分析仪和Ｘ射线衍仪定量研究了Ｎｉ在球铁中的分布和Ｎｉ铸态球铁组成相比例奥氏体中含碳量以及贝氏体转变ＴＴＴ曲线线的影响，结果表明，Ｎｉ在球铁中呈连续负偏析，其加入可以影响球铁组成上比例，并使粤氏体中含碳量和贝氏体转变孕育期期增加。     

Cloning and sequencing of a tpr-met oncogene cDNA isolated from MNNG-transformed human XP fibroblasts

A rearranged tpr-met oncogene was identified in a MNNG-transformed human Xeroderma pigmentosum (XP) cell line (ASKMN). A 2016 bp cDNA was cloned and sequenced, disclosing an ORF with a coding capacity for a 523 aa protein. The sequence of this tpr-met cDNA was very similar to that previously reported in another human MNNG-transformed cell line (MNNG-HOS).     

铯原子激光共振电离

用Ｎｄ：ＹＡＧ及其泵浦的染料激光进行铯原子三步共振电离。求解了非饱和共振过程速率方程，计算出基态和激发态共振吸收截面，给出电离效率分别与激发电离速率以及作用时间的变化关系，得到饱和激发电离的流量条件和通量条件。     

人工智能方法用于熔喷过程在线检测的研究

熔喷生产最终产品质量的控制，对于过程优化具有重要的意义。产品质量的在线检测是过程监测与质量控制必不可少的。本文首次在熔喷系统中引入人工智能的研究方法，对熔喷非织造布的厚度与纤维直径进行在线预测。实测数据与人工神经网络的预测结果吻合较好，从而证实了人工神经网络用于模拟熔喷过程的可行性。网络的输入包括：挤出机温度、喷头温度、熔融体挤出速率、空气流率及接收距离。神经元计算的输出是纤维直径与熔喷非织布的厚度。文中进一步提出了将神经网络与专家系统相结合的研究路线，以实现熔喷过程的优化控制。     

可调90°偏振面旋转器

给出一种可调式90°偏振面旋转器。调整复合片快轴的夹角α,便能在可见光范围内使用.     

国外模拟IC的发展现状分析

本文主要根据电子整机的发展要求,从集成化、高性能和高可靠等三方面分析国外模似IC的发展,进而说明模拟IC总的发展趋势及其表现。最后指出,模拟IC正面临一个新的变革时期。     

Hydride Vapor Phase Epitaxy of GaN Thick Films by the Consecutive Deposition Process Using GaCl3

GaN buffer and main layers were grown by the conventional hydride vapor phase epitaxy technique using GaCl₃ consecutively. The deposited buffer layers were investigated by atomic force microscopy and X-ray analysis. To examine the behavior of the buffer layers at main layer growth temperature, heat treatment was conducted at 900°C. Based on the results of the buffer layer study, GaN thick films were grown at 1050°C. Optimum deposition conditions of buffer layer from the buffer and main layer studies generally coincided. On the φ scanning pattern, the GaN films grown on (0001) Al₂O₃ were single-crystalline. Band-edge emission dominated photoluminescence was observed at room temperature.