Phorbol ester and diacylglycerol induce protein phosphorylation at tyrosine

The phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA) is an efficient tumour promoter in vivo. In vitro, TPA activates the phospholipid- and Ca2+-dependent protein kinase, kinase C. This activation is believed to reflect the structural similarity between TPA and diacylglycerol, the endogenous protein kinase C activator which is produced in vivo by hydrolysis of phosphatidylinositol (reviewed in ref. 3). Protein kinase C phosphorylates protein substrates at serine and threonine residues in vitro. The effects of TPA on cultured fibroblasts--including enhanced hexose uptake, disruption of actin stress fibres and growth stimulation--are very similar to those induced by certain retrovirus transforming proteins and by peptide growth factors such as epidermal growth factor (EGF), platelet-derived growth factor (PDGF) and multiplication-stimulating activity (MSA). These transforming proteins and mitogenic agents seem to act by inducing tyrosine-specific protein phosphorylation. Such observations suggested that some of the effects of TPA in vivo may be mediated by protein phosphorylation at tyrosine residues. A 42,000-molecular weight (42 K) polypeptide was previously shown to be phosphorylated at tyrosine in cells transformed by avian sarcoma viruses and in cells stimulated by EGF, PDGF or MSA (J. Cooper, personal communication and refs 11 and 12; this polypeptide was originally designated 43 K or spot n in ref. 10). We show here that this polypeptide also becomes phosphorylated at tyrosine in cells treated with TPA. Furthermore, exogenously added diacylglycerol likewise stimulates the phosphorylation of this protein at tyrosine.     

Colony promoting activity and its target 'pre-CFUc' in genetically anemic mice of W/Wv genotype

Incubation of bone marrow cells with supernatant from long-term cultures of bone marrow cells increases the number of granulocyte-macrophage progenitor cells. This study reveals the presence of target cells of the colony promoting activity (CPA) in W/Wv mouse marrow. It is also shown that CPA does not stimulate erythroid colony formation in vitro.     

Functional architecture of cortex revealed by optical imaging of intrinsic signals

Optical imaging of cortical activity offers several advantages over conventional electrophysiological and anatomical techniques. One can map a relatively large region, obtain successive maps to different stimuli in the same cortical area and follow variations in response over time. In the intact mammalian brain this imaging has been accomplished with the aid of voltage sensitive dyes. However, it has been known for many years that some intrinsic changes in the optical properties of the tissue are dependent on electrical or metabolic activity. Here we show that these changes can be used to study the functional architecture of cortex. Optical maps of whisker barrels in the rat and the orientation columns in the cat visual cortex, obtained by reflection measurements of the intrinsic signal, were confirmed with voltage sensitive dyes or by electrophysiological recordings. In addition, we describe an intrinsic signal originating from small arteries which can be used to investigate the communication between local neuronal activity and the microvasculature. One advantage of the method is that it is non-invasive and does not require dyes, a clear benefit for clinical applications.     

过滤器的安全模型框架

采用Ｂｅｌｌ－ＬａＰａｄｕｌａ（ＢＬＰ）模型的风格及其表述方法，讨论了信息过滤器一类系统的安全模型框架。提出的过滤器模型框架扩充了ＢＬＰ模型的适用范围。结果表明，ＢＬＰ模型不仅适用于操作系统的建模，而且还适用于其它的一类系统建模。     

高阶抽象Cauchy问题的解析性与指数稳定性

研究高阶抽象Ｃａｕｃｈｙ问题的解及其传播算子的解析性与指数稳定性，得到一些基本结果。同时给出了所得结果对抛物方程的混合问题的应用例子。     

高速铁路车辆轴承试验机微机监控与诊断系统

介绍了所研制的高速铁路车辆轴承试验机微机监控与诊断系统；重点讨论了工况监视与诊断的实现技术；并把该系统成功地应用于高速铁路车辆轴承的模拟试验中．     

全混洗光互连的矩阵处理与研究

引入矩阵的方法分析处理全混洗互连变换，用矩阵方程形式直观地表达了一些已知的，以及一些新的全混洗互连性质，并阐明了其物理意义，同时提出了全混洗互连、逆全混洗互连的光学实现方法。