植物种子萌发过程的多胺氧化酶定位方法研究

多胺氧化酶 (PAO)在植物的生长发育过程起着重要作用。开展PAO的细胞定位研究是探讨该酶生理功能的有效途径。氯化铈法是常用的电镜PAO定位方法 ,此法利用PAO能与铈离子结合形成不溶性的电子致密物 铈沉淀 ,用电镜观察确定PAO在细胞超微结构中所存在的部位。1　材料与方法花生种子、菜豆种子、黄豆种子。种子经消毒处理后 ,浸泡后于湿润的滤纸上发芽。取萌发 5日的幼叶、顶芽、子叶、胚轴、根 ,4 %戊二醛固定洗涤 ,常温孵育 30～ 6 0min(孵育液每样用10mmol LCeCl 3∶10mmol L腐胺∶pH7.0磷酸缓冲液 =2∶2∶1,对照 10mmol LCeCl …     

Lymphocyte proliferation and differentiation in chronic lympholeukemia

Proliferative activity and differentiation levels of lymphocytes of lymph nodes and peripheral blood of practically healthy people and patients with chronic lymphocytic leukemia have been studied using the present physicochemical methods (autoradiography with labelled DNA and RNA precursors, microspectrocytometry, NMR spectroscopy, kinetic formaldehyde method, etc.). The following points have been stated: stage character of changes in normal and leukemic cells, differences in synthesis of nucleic acids in different periods of the cell cycle in norm and under chronic lymphocytic leukemia, proliferation peculiarities of lymphocytes in lymph nodes and in blood, presence of DNA defects in the process development, changes in lipids of lymphocytes and blood plasma at early stages of the disease and in the process of its development.     

Models of boron redistribution during thermal oxidation withgeneral oxidation rate

It has been shown that the redistribution of boron in SiO₂ is negligible in the practical temperature range between 900 and 1100°C. Utilizing this fact, we derived a model for boron redistribution with a general oxidation rate, and obtained close agreement between experimental and theoretical data     

生物细胞氧化应激模型探讨

缺血再灌注、药物代谢、金属中毒等使体内促氧化剂 :过氧化氢 ( H2 O2 )、超氧阴离子 ( O　·2 )、羟自由基 ( OH· )等自由基的大量形成 ,使机体氧化与抗氧化系统失去平衡 ,引生物细胞氧化应激 ,导致蛋白、脂质的过氧化 ,目前已知铁盐或 Fe2 + 可催化体内最强促氧化剂 OH· (羟自由基 )的大量形成 ,如 O　·2 + H2 O2 OH· + O2 ,H2 O2 + Fe2 + Fe3+ + OH- + OH· 。而且 H2 O2 易发生均裂形成 OH· 。促氧化剂 H2 O2 除自身具有氧化作用外其过量产生 ,可导致 OH· 的大量形成进而加剧蛋白质及脂质的氧化损伤。经多次实验结果…     

Multi-scale engineering for neuronal cell growth and differentiation

In this paper we investigate the role of micropatterning and molecular coating for cell culture and differentiation of neuronal cells (Neuro2a cell line) on a polydimethylsiloxane substrate. We investigate arrays of micrometric grooves (line and space) capable to guide neurite along their axis. We demonstrate that pattern dimensions play a major role due to the deformation of the cell occasioned by grooves narrower than typical cell dimension. A technological compromise for optimizing cell density, differentiation rate and neurite alignment has been obtained for 20 μm wide grooves which is a dimension comparable with the average cell dimension. This topographical engineered pattern combined with double-wall carbon nanotubes coating enabled us to obtain adherent cell densities in the order of 10⁴ cells/cm² and a differentiation rate close to 100%.     

Vector synthesis problem of random geometry antenna differentiation conditions

The problem definition of general random geometry continuous and discontinuous antenna vector synthesis is discussed. Conditions are formulated which allow presenting the initial antenna vector synthesis problem in the form of array of some scalar synthesis problems while locating the antenna in the free space and near the surface. On plane, cylinder and sphere examples antenna synthesis problems division possibilities of scalar problems are examined.     

人参总皂苷对K562细胞的增殖抑制及诱导分化作用

目的:研究人参总皂苷TSPG对人慢性粒细胞白血病细胞株(K562细胞)增殖及分化的影响,探讨TSPG抗肿瘤作用.方法:取对数生长期K562细胞,分为阴性对照组、不同浓度TSPG组及阳性对照组进行体外培养,以噻唑蓝(MTT)比色法、台盼蓝活细胞计数法观察TSPG对K562细胞增殖的影响;用联苯胺染色及血红蛋白测定检测其诱...     

Predictive significance of parameters of tumor cell proliferation

Recent publications on prognostic significance of tumour cell proliferation parameters (mitotic index, 3H-thymidine labelling index, cell cycle distributions using DNA-measurements) in certain human tumours are reviewed. Data on acute leukaemia are controversial. In all other haematological and non-haematological malignancies the cell proliferation parameters correlated inversely with survival rate of patients and with the duration of the relapse-free period. Practical application of these data are discussed.     

Photonic effects during low-temperature ultraviolet-assisted oxidation of SiGe

The behavior of Ge atoms during dry oxidation of Si_0.8Ge_0.2 films at 300°C under 10 mbar of oxygen induced by vacuum-ultraviolet (VUV) illumination from an array of Xe₂* excimer lamps (λ=172 nm) has been studied. During VUV oxidation, samples are exposed to both a high concentration of ozone and atomic oxygen and a large flux of energetic photons. X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) spectroscopy investigations showed that the layers grown for shorter periods of time contain mostly SiO₂ with a few percent GeO₂. Most of the Ge atoms, initially present uniformly within the SiGe layer, were segregated and accumulated at the interface between the grown oxide and remaining SiGe. Angle-resolved XPS showed that the amount of GeO₂ within the grown oxide layer decreased for longer irradiation times and was located adjacent to the SiGe layer. When the grown SiO₂ layer reached a thickness around ～70 Å and the amount of Ge that had accumulated in the segregated layer more than doubled, a sharp increase in the Ge oxidation rate was observed. Continuing the oxidation for longer irradiation times resulted in the formation of a mixed oxide layer. The Ge segregation was not previously observed during other low-temperature oxidation treatments, including ozone-assisted oxidation, which provides the same oxidation species as VUV-assisted oxidation and similar growth rates. It is, therefore, concluded that a VUV photon-irradiation enhancement effect on Si and Ge interdiffusion has been introduced, possibly involving either Si-Si or Si-Ge bond softening or even breaking.     

Proliferation and differentiation of hematopoietic stem cells during tumor growth

The influence of transplantable tumour on migration, proliferation and differentiation of haemopoietic stem cells was studied. It is shown that in the initial period of tumour development the migration and proliferation of stem cells intensify. In the final stage of the tumour growth the quantity of haemopoietic stem cells decreases considerably in the bone marrow, spleen, and peripheral blood. It is established that during the tumour growth the differentiation of stem cells from the spleen changed towards erythropoiesis.     

人工林毛白杨次生木质部细胞分化过程中木质素沉积的动态变化

本文以高锰酸钾(KMnO4)染色及醋酸双氧铀和柠檬酸铅双染色两种方法,利用透射电镜技术(TEM)研究人工林毛白杨(Populus tomerttosa Carr．)木质部细胞分化过程中木质素在细胞壁上的沉积方式,并讨论了细胞壁结构与木质素沉积之间的关系。观察结果表明,木质素最早出现在位于初生壁的细胞角隅处,以分散的条形颗粒状沉积。随着S1和S2层纤维素微纤丝(CMfs)的沉积,木质素开始沿初生壁角隅处,向胞间层其它区域和次生壁各层同时扩展,整个木质化过程并不是由胞间层依次向次生壁各层推进。S3层的CMfs沉积后,木质素在整个次生壁开始迅速沉积。次生壁上的木质素主要以不均匀团块状方式沉积,且各层交界处的木质素沉积较少。胞问层沉积的木质素多且较次生壁沉积的更为致密。木质素的沉积方式可能与细胞壁各层纤维素微纤丝骨架的不同结构密切相关。     

Ultracytochemistry of enzymes in cell biology of the retina.

In matured chick retina, alkaline phosphatase activity is specifically localized in the outer plexiform layer and in the horizontal and Müller cells. In developing chick retina, the activity is recognized in growing neurites from horizontal cells, when synaptogenesis begins in the outer plexiform layer. Using levamisole, a potent inhibitor of alkaline phosphatase, on chick retina in vivo and in vitro, the enzyme was shown to play a significant role in retinal cell differentiation. 5'-Nucleotidase is used as a marker for the rod photoreceptors. It became apparent that the 'displaced' rod cells are localized in the inner nuclear layer of postnatal retina. High activity of glucose-6-phosphatase is confirmed in the cisternae of the smooth and rough endoplasmic reticulum, together with the space of the perinuclear envelope in the pigment epithelium of rat. The process of disc membrane recycling in the rod outer segment was investigated cytochemically to reveal sequential changes in lysosomal digestion both by conventional enzyme cytochemistry and by high voltage electron microscopy. With conventional enzyme histochemistry as well as with rapid freeze substitution enzyme cytochemistry, all enzyme for cGMP metabolism were observed to be on the cytoplasmic side of the disc membranes.     

Enhancement of Signal-to-Noise Ratio during the Detection of Weak Video Pulses

A device has been proposed for enhancing the signal-to-noise ratio at the output of optimal filter during the detection of weak video pulses. This effect was achieved at the expense of cutting off the negative surges of noise by the instantaneous nonlinear circuit having the characteristic of “linear detector” (diode with resistive load) connected before the optimal filter. The computational relationships were presented and the calculation results were corroborated by experimental data     

Generation kinetics of oxide charges and surface states during oxidation of silicon

A simple model to account for the generation kinetics of oxide charges and surface states during oxidation of silicon is presented. In the model, oxide charges and surface states are generated by a reaction between silicon and oxygen within the mono-molecular layer of the Si/SiO₂ interface and are thermally annealed independently of this reaction. A two step oxidation technique was used to investigate the electronic structure of the Si/SiO₂ interface and it was found that centers of fast surface states are located within 1.4–2.0 Å of the interface and that the centroid of oxide charges is located at about 8 Å from the interface. These results agreed with the model.     

水稻胚乳细胞淀粉质体被膜与其增殖的关系

水稻胚乳细胞经高锰酸钾固定法固定后，显示出十分清晰的内膜结构，尤其展现了淀粉质体被膜与淀粉质体增殖在结构上的密切关系。常见的淀粉质体出芽、缢缩和形成中间隔板的增殖方式分别与淀粉质体外层被膜、内外层被膜、内层被膜的活动有关。另外，淀粉质体外层被膜也能出芽，形成双层膜小泡，再积累淀粉形成淀粉质体；而淀粉质体内层被膜向内出泡或内外层被膜同时内陷，在淀粉体内形成新淀粉质体，这是淀粉质体增殖的两种新方式。对淀粉质体被膜在淀粉质体增殖中的作用进行了讨论。     

Leakage power analysis and reduction during behavioral synthesis

This paper presents a high-level leakage power analysis and reduction algorithm. The algorithm uses device-level models for leakage to precharacterize a given register-transfer level module library. This is used to estimate the power consumption of a circuit due to leakage. The algorithm can also identify and extract the frequently idle modules in the datapath, which may be targeted for low-leakage optimization. Leakage optimization is based on the use of dual threshold voltage (V/sub T/) technology. The algorithm prioritizes modules giving a high-level synthesis system an indication of where most gains for leakage reduction may be found. We tested our algorithm using a number of benchmarks from various sources. We ran a series of experiments by integrating our algorithm into a low-power high-level synthesis system. In addition to reducing the power consumption due to switching activity, our algorithm provides the high-level synthesis system with the ability to detect and reduce leakage power consumption, hence, further reducing total power consumption. This is shown over a number of technology generations. The trend in these generations indicates that leakage becomes the dominant component of power at smaller feature size and lower supply voltages. Results show that using a dual-V/sub T/ library during high-level synthesis can reduce leakage power by an average of 58% for the different technology generations. Total power can be reduced by an average of 15.0%-45.0% for 0.18-0.07 /spl mu/m technologies, respectively. The contribution of leakage power to overall power consumption ranges from 22.6% to 56.2%. Our approach reduced these values to 11.7%-26.9%.     

低强度激光对软骨胶原合成和细胞增殖影响

研究了810 nm低强度Ga-Al-As半导体激光对兔软骨细胞增殖和胶原合成的影响.取新西兰白兔的关节软骨细胞,用浓度为2%的新生牛血清(NCS)培养媒介培养.激光功率密度分别为1.75、3.50、5.25、7.00和8.75 mW/cm2,以连续方式每天照射软骨细胞5 min,共5 d.分别用四甲基氮唑盐(MTT)法和氯胺T消化法检测细胞的增殖和胶原蛋白合成.结果发现:第8天实验结束时,各激光照射组细胞数量随激光强度线性增加,与无激光照射组的差异有统计学意义(P＜0.01),其中最佳照射功率密度为7.00 mW/cm2;第8天实验结束时,激光照射组胶原含量显著低于对照组(P＜0.01),8.75 mW/cm2组与3.50～7.00 mW/cm2组有显著差异(P＜0.05).激光照射7.00 mW/cm2组与对照组第2、4、6和8天胶原含量的测定表明,照射组胶原含量先增加后降低,其中第6天照射组胶原含量最高,与相应对照组有极显著差异(P＜0.01),对照组胶原含量在第6天后急剧增加,第8天与照射组有极显著差异(P＜0.01).研究结果表明,低强度Ga-Al-As半导体激光能促进兔关节软骨细胞的生长,有望成为临床治疗软骨损伤的一种有效方法.     

DNA alkylation during endogenous synthesis of N-nitrosodimethylamine

The simultaneous administration of 14C-dimethylamine and sodium nitrite to rat stomach produces the formation of O6-methylguanine and 7-methylguanine in the liver DNA as a result of the endogenic synthesis of N-nitrosodimethylamine (NDMA). Methylation of DNA was also observed in the rat kidney and lung. Alkylation of O6-position of guanine and removal of its methylated product from the DNA occurred in the liver to a greater extent than in the other NDMA target organs. Pretreatment of rats with sodium nitrite increased the alkylation of liver DNA caused by endogenic synthesis of NDMA. The formation of alkylated products in DNA may be used as a marker for the endogenic formation of NDMA from precursors.     

Approximate solution for the redistribution of impurities during second oxidation

The impurity profile for the second oxidation, used in MOST fabrication, has been obtained by Margalit et al. [1]. The disadvantage of this technique is that the accuracy of their solution is directly dependent on the computer time. In this article, an analytical solution is presented using the approximation of linearizing the second oxidation procedure.