酵母双杂交筛选锥虫早老素蛋白相互作用蛋白

目的筛选寻找锥虫早老素蛋白相互作用蛋白,以了解锥虫早老素蛋白功能。方法体外表达锥虫早老素蛋白片段,装入pGBKT7诱饵质粒,与随机肽库系统共转化酵母,筛选阳性克隆并测序,通过与基因库锥虫功能序列比较,推导可能的相互作用蛋白。结果获得108个阳性克隆,对其中50个进行了序列测定和比较,获得最有可能的4个候选基因,分别为：丝/苏氨酸性磷酸酶2b催化亚基A2;钙激活蛋白,含锚蛋白重复序列蛋白以及一个具有与APP跨膜区结合位点特征序列的功能未知蛋白。结论成功利用随机肽库酵母双杂交系统筛选锥虫早老素蛋白相互作用基因,其相互作用仍有待进一步确认。     

薏苡茎总碱抗氧化性研究

目的：研究薏苡茎总碱的抗氧化性.方法：用超声辅助法（以75％乙醇作为溶剂）和减压蒸发辅助法（利用旋转蒸发仪）提取薏苡茎总碱;用普鲁士法测定其对Fe3＋的还原能力;用紫外分光光度法测定其清除DPPH自由基的能力、清除超氧自由基的能力、用丁基羟基茴香醚（butylated hydroxylanisole,BHA）作对照测定其对Fe2＋的螯合能力.结果：薏苡茎总碱有较强的还原Fe3＋的能力、清除DPPH自由基的能力、清除超氧自由基的能力、螯合金属离子Fe2＋的能力.结论：薏苡茎总碱具有较强的抗氧化性.     

稳定表达β-synuclein的SH-SY5Y细胞株的构建

目的构建稳定表达β-synuclein的SH-SY5Y细胞株。方法利用脂质体转染技术将质粒pcD-NA3.1-β-synuclein转染SH-SY5Y细胞,通过Zeocin进行抗性筛选。采用原位免疫荧光、免疫组织化学染色及Western blot杂交检测β-synuclein在SH-SY5Y细胞中的表达情况;通过MTT比色法检测β-synuclein稳定表达对SH-SY5Y细胞增殖的影响。结果原位免疫荧光、免疫组织化学染色及Western blot检测结果显示β-synuclein在SH-SY5Y细胞中的表达水平较对照组明显升高;稳定表达β-synuclein的细胞增殖程度较对照组明显增高(P<0.05)。结论β-synuclein在SH-SY5Y细胞中稳定表达,为后续的研究提供有用的细胞模型。为进一步研究β-sy-nuclein对帕金森病发病神经保护作用的研究奠定了良好的基础。     

脑深部电刺激的临床应用

脑深部电刺激(deep brain stimulation,DBS)是近20年来神经外科领域发展最迅猛的技术。DBS是通过刺激发生器发出的高频电脉冲信号刺激脑神经核团或神经传导束来调节异常的神经环路。DBS已经成为治疗特发性震颤、帕金森病、肌张力障碍等运动障碍病的常规手术方法。自1997年深部脑刺激通过美国FDA认证用于治疗特发性震颤以来,已有超过数万名运动障碍患者接受该疗法,而国内脑深部电刺激最早在1999年应用于帕金森病临床治疗,迄今也有数千例患者接受了植入手术。近年,脑起搏器的临床适应症不断扩大,从最初的运动障碍病逐渐发展到治疗其他神经和精神疾病,如抽动秽语综合征、强迫症、抑郁症、神经性厌食症、难治性疼痛、癫痫、植物状态和阿尔茨海默病等,虽然DBS的治疗机理还不很清楚,但可以预见未来DBS将成为众多神经和精神疾病的重要治疗方法。     

Quantitative analysis of multiple forest disturbances and their compound influences on tree growth in the western U.S.

As the frequencies of extreme weather increase, forest ecosystems experience stronger influences from various disturbances. Previous research focuses on single disturbances or qualitative analysis of overlaid effects from two disturbances. Studies rarely explored the interactions between three or more disturbances, especially mechanisms behind the multiple disturbances. Our study covered four states (Idaho, Montana, Wyoming, and Utah) in the U.S. which shared similar climate patterns and vegetation distributions. We collected 241 chronologies from the International Tree-Ring Data Bank (ITRDB) and our own field expeditions. We assigned each tree ring to eight possible disturbance combinations. From the correlations between tree indices and climate (monthly temperature and total precipitation), the radial growth of tree rings showed a significant positive correlation with summer precipitation and a negative correlation with summer temperature. With three-factor ANOVA and one-way ANOVA, we ranked the impacts of each disturbance and combination of disturbances on tree growth based on tree-ring index; control (1.038) > insect (1.029) > fire (1.008) > fire & insect (0.963) > drought & insect (0.918) > drought (0.890) > drought, fire & insect (0.803) > drought & fire (0.784). We found that in most cases, the combined impact from two disturbances was larger than the impacts from single disturbances with the inclusion-exclusion principle. This research quantitatively revealed the interactions between disturbances and evaluated the effects from a combination of multiple disturbances.     

Conceptual challenges to the harm threshold

Children are presumptively regarded as incompetent to make their own medical decisions, and the responsibility for making such decisions typically falls to parents. Parental authority is not unlimited, however, and ethical guidelines identifying appropriate bounds on this authority are needed. One proposal currently gaining support is the harm threshold (HT), which asserts that the state may only legitimately intervene in parental decision-making when serious and preventable harm to children is likely. This paper considers two questions: in virtue of what underlying principle or property does the HT gain its purported justification?; and does this underlying principle or property ground the HT as its proponents conceive of it? I identify two separate grounds represented in the literature: (a) J.S. Mill’s Harm Principle; and (b) the liberty interests of parents. I find that the HT is not sufficiently grounded in either of these, revealing a substantial conceptual difficulty for its advocates.     

On the combination of equality and inequality restrictions on regression coefficients

The paper gives a method for using equality and inequality restrictions simultaneously. This is done by combining the estimator for linear equality restrictions and the minimax linear estimator principle which was developed for inequality restraints. The result is a ridge-type estimator, namely a biased so-to-speak minimax-linear estimator (MMLE) which dominates the classical MMLE in the sense of smaller MSE.     

Biomechanical analysis of passive flow of stromatoporoids — morphologic, paleoecologic, and systematic implications

Boyajian, George E. & LaBarbera, Michael 1987 07 15: Biomechanical analysis of passive flow of stromatoporoids - morphologic, paleoecologic, and systematic implications.
Investigation of the functional significance of astrorhizae (surficial canals) in some stromatoporoids is necessary to understand the structure and evolutionary affinities of these organisms. To this end, scale models of stromatoporoids with mamelons and astrorhizae were subjected to laminar flow conditions within a flow tank. Flow patterns were traced using dye streams. Dye was observed to enter the distal ends of the astrorhizae and flow to the top of the mamelon (mounds from which astrorhizae radiate) where it entered the overlying current and was removed. Similar flow patterns were observed in Living sclerosponges which display astrorhizal and mamelon structures. Excurrent (dyed) water was not refiltered by the model, or Living organism, thus demonstrating the ability of astrorhizae to function efficiently as excurrent canals. In the model viscous entrainment may aid the flow, but pressure differentials due to the velocity gradient above the mamelons account for most of the flow. In living sclerosponges, active pumping by the living organism accounts for most of its flow; passive mechanisms aid to an unknown degree. If stromatoporoid morphology is plastic and dependent on local environmental influences, local paleocurrent velocities may be deduced by examining the height and spacing of mamelons in fossil stromatoporoids; consequently, mamelons should not be. used as criteria in stromatoporoid systematics. These findings are consistent with Steam's reconstruction of the stromatoporoid animal and his proposed function of astrorhizae.     

A structural and a functional aspect of stable information processing by the brain

Brain is an expert in producing the same output from a particular set of inputs, even from a very noisy environment. In this article a model of neural circuit in the brain has been proposed which is composed of cyclic sub-circuits. A big loop has been defined to be consisting of a feed forward path from the sensory neurons to the highest processing area of the brain and feed back paths from that region back up to close to the same sensory neurons. It has been mathematically shown how some smaller cycles can amplify signal. A big loop processes information by contrast and amplify principle. How a pair of presynaptic and postsynaptic neurons can be identified by an exact synchronization detection method has also been mentioned. It has been assumed that the spike train coming out of a firing neuron encodes all the information produced by it as output. It is possible to extract this information over a period of time by Fourier transforms. The Fourier coefficients arranged in a vector form will uniquely represent the neural spike train over a period of time. The information emanating out of all the neurons in a given neural circuit over a period of time can be represented by a collection of points in a multidimensional vector space. This cluster of points represents the functional or behavioral form of the neural circuit. It has been proposed that a particular cluster of vectors as the representation of a new behavior is chosen by the brain interactively with respect to the memory stored in that circuit and the amount of emotion involved. It has been proposed that in this situation a Coulomb force like expression governs the dynamics of functioning of the circuit and stability of the system is reached at the minimum of all the minima of a potential function derived from the force like expression. The calculations have been done with respect to a pseudometric defined in a multidimensional vector space.     

Maximum-entropy principle: ecological organization and evolution

In the present paper, we have first studied the role of the maximum-entropy principle to explain the concept of organization of a physical system in the decreasing law of entropy with the increase of external constraints imposed on the system. We have then considered an open ecosystem (living) and determined a quantitative measure of ecological organization from the consideration of the thermodynamics of irreversible processes. Finally, we have tried to explain the evolution of the ecosystem in the light of Prigogine’s principle of “order through fluctuation.”