Neuronal autophagy and neurodegenerative diseases

Autophagy is a dynamic cellular pathway involved in the turnover of proteins, protein complexes, and organelles through lysosomal degradation. The integrity of postmitotic neurons is heavily dependent on high basal autophagy compared to non-neuronal cells as misfolded proteins and damaged organelles cannot be diluted through cell division. Moreover, neurons contain the specialized structures for intercellular communication, such as axons, dendrites and synapses, which require the reciprocal transport of proteins, organelles and autophagosomes over significant distances from the soma. Defects in autophagy affect the intercellular communication and subsequently, contributing to neurodegeneration. The presence of abnormal autophagic activity is frequently observed in selective neuronal populations afflicted in common neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis. These observations have provoked controversy regarding whether the increase in autophagosomes observed in the degenerating neurons play a protective role or instead contribute to pathogenic neuronal cell death. It is still unknown what factors may determine whether active autophagy is beneficial or pathogenic during neurodegeneration. In this review, we consider both the normal and pathophysiological roles of neuronal autophagy and its potential therapeutic implications for common neurodegenerative diseases.     

Conducting swift heavy ion track networks

In this paper, the electronic behavior of conducting swift heavy ion track networks is studied. On the one hand, the transient conductivity of ion tracks in metal oxides on silicon in status nascendi is exploited for this purpose, and on the other hand, conducting tracks are produced by ion irradiation of insulating membranes (either self-supported or deposited onto silicon substrates), subsequent etching and finally inserting conducting materials of whatever provenience (in this work preferentially electrolytes). Depending on their manufacture, the conducting tracks either act as electronically active or passive elements. When applying a voltage across individual tracks in the first case, one observes current spikes with negative differential resistances. These tracks interact among themselves, leading to phase-locked synchronous coupled oscillations with complex patterns that are quite similar to those emerging from neural networks. The other case corresponds to networks of electronically passive conducting tracks which become overall electronically active only through their collective interactions. Though the aforementioned effects had been experimentally described earlier, they are re-visited here to make clear that the corresponding systems have to be considered as being artificial neural networks. On this occasion, some new findings are added.     

连续多阈值神经元反馈神经网络盲检测光基带信号

空间分集接收可补偿信道衰落,提出了一种基于幅相联合激励法的连续多阈值神经元反馈神经网络(RNNCMVN)的光基带信号直接盲检测方法。针对多进制相移键控(MPSK)信号的特点,设计了两种连续相位多阈值激励函数形式,并简要讨论了该两类激励函数参数的选择;分别推演基于幅相联合激励法的RNNCMVN光基带信号盲检测方法工作于同步和异步两种模式下的新能量函数及其相关证明。同时针对正交调幅(QAM)信号的特点,分别设计出连续振幅和相位多阈值激励函数形式,最后通过仿真验证了该方法的有效性。     

Electric Field-induced dynamical evolution of spiral wave in the regular networks of Hodgkin-Huxley neurons

An additional gradient force is often used to simulate the polarization effect induced by the external field in the reaction-diffusion systems. The polarization effect of weak electric field on the regular networks of Hodgkin-Huxley neurons is measured by imposing an additive term V_E on physiological membrane potential at the cellular level, and the dynamical evolution of spiral wave subjected to the external electric field is investigated. A statistical variable is defined to study the dynamical evolution of spiral wave due to polarization effect. In the numerical simulation, 40000 neurons placed in the 200 × 200 square array with nearest neighbor connection type. It is found that spiral wave encounters death and the networks become homogeneous when the intensity of electric field exceeds the critical value, otherwise, spiral wave keeps alive completely. On the other hand, breakup of spiral wave occurs as the intensity of electric field exceeds the critical value in the presence of weak channel noise, otherwise, spiral wave keeps robustness to the external field completely. The critical value can be detected from the abrupt changes in the curve for factors of synchronization vs. control parameter, a smaller factor of synchronization is detected when the spiral wave keeps alive.     

Examples of Scientific Problems and Data Analyses in Demography,Neurophysiology, and Seismology

Examples of scientific problems and data analyses are presented for the fields of demography, neurophysiology, and seismology. The examples are connected by the involvement of space or time. The demographic problem is to display quantities derived from spatially aggregated data and associated measures of uncertainty. The neurophysiological problem is to infer the presence of complex pathways among groups of neurons given sequences of firing times. There are two seismological problems: (1) to determine isoseismals of recorded intensities following the Loma Prieta earthquake and (2) to relate intensity and acceleration values measured at distinct locations. The statistical analyses are connected to each other by the application of smoothing in some form and by the provision of consequent graphical displays.     

LMI-based robust adaptive synchronization of FitzHugh-Nagumo neurons with unknown parameters under uncertain external electrical stimulation

This Letter addresses a nonlinear robust adaptive control that utilizes linear matrix inequalities for asymptotic synchronization of two coupled chaotic FitzHugh-Nagumo neurons under unknown parameters and uncertain stimulation current amplitudes and phase shifts. Synchronization of chaotic neurons using the proposed control method through numerical simulation is demonstrated.     

镧对仔鼠嗅感觉神经元分化中β—Ⅲ微管蛋白的作用

为观察发育期氯化镧暴露对仔鼠嗅觉功能及β-Ⅲ微管蛋白表达的影响,将16只Wistar孕鼠随机分为两组（对照组、氯化镧组）,对照组母鼠饮用蒸馏水,氯化镧组饮用0．25％氯化镧溶液;仔鼠出生后25d采用嗅觉迷宫试验检测仔鼠嗅觉功能的差异;于出生后28d采用免疫荧光和免疫印迹观察仔鼠β-Ⅲ微管蛋白在嗅上皮的表达变化。结果表明,氯化镧组仔鼠在嗅觉迷宫试验寻找食物的时间较对照组长,差异具有统计学意义（P〈0．05）;氯化镧组下调仔鼠嗅上皮β-Ⅲ微管蛋白在嗅感觉神经元的表达。提示镧暴露损害子代嗅觉功能,可能与镧损害嗅上皮β-Ⅲ微管蛋白的表达有关。     

关于周期神经网络逼近阶的研究

借助于有关Fourier级数的Riesz平均构造出了一类含有一个隐含层的周期神经网络与平移网络,与已有的讨论相比较,在获得相同的逼近阶的情况下,此类网络的隐层单元要求较少的神经元个数.     

Quercetin-albumin nano-complex as an antioxidant agent against hydrogen peroxide-induced death of spinal cord neurons as a model of preventive care study

Herein, the quercetin-human serum albumin (HSA) nano-complex was formulated and its capability to decrease H₂O₂-stimulated cytotoxicity against spinal cord neurons as a model of preventive care study was investigated by cellular assays. Quercetin molecules were first encapsulated into HSA as a shell and the loading efficiency along with drug release and different properties of formulated nano-complex were determined using TEM, SEM, and DLS approaches. Afterwards using CD spectroscopic method and theoritical analysis, the structural changes and binding redisues of HSA after interaction with quercetin were investigated, respectively. Finally, the antioxidant activity of quercetin-HSA nano-complex against H₂O₂ (200 µM)-stimulated cytotoxicity in spinal cord neurons was explored by MTT, SOD and CAT activity, and morphological changes assays. It was shown that the fabrication of quercetin-HSA nano-complex resulted in the improved bioavailability of quercetin with an entrapment efficiency of 68.99% and percent yield of 53.19%. Also, molecular docking study showed that quercetin molecules spontaneously bind to HSA through hydrogen bonds and van der Waals interactions. Furthermore, CD data indicated that the quercetin did not change the secondary structure of HSA. Finally, cellular assays displayed that the pre-treatments of spinal cord neurons with quercetin-HSA nano-complex attenuated the H₂O₂-triggerd neuron mortality through a significant increase in the activity of SOD and CAT and prevention of morphological changes. In conclusion, it may be suggested that the formulation of quercetin into nano-complex can improve its medical properties and this new developed drug formulation may hold a great promise in the advancement of antioxidant compounds in preventive care services.