Identification of NCAM-binding peptides promoting neurite outgrowth via a heterotrimeric G-protein-coupled pathway

A combinatorial library of undecapeptides was produced and utilized for the isolation of peptide binding to the fibronectin type 3 modules (F3I–F3II) of the neural cell adhesion molecule (NCAM). The isolated peptides were sequenced and produced as dendrimers. Two of the peptides (denoted ENFIN2 and ENFIN11) were confirmed to bind to F3I–F3II of NCAM by surface plasmon resonance. The peptides induced neurite outgrowth in primary cerebellar neurons and PC12E2 cells, but had no apparent neuroprotective properties. NCAM is known to activate different intracellular pathways, including signaling through the fibroblast growth factor receptor, the Src-related non-receptor tyrosine kinase Fyn, and heterotrimeric G-proteins. Interestingly, neurite outgrowth stimulated by ENFIN2 and ENFIN11 was independent of signaling through fibroblast growth factor receptor and Fyn, but could be inhibited with pertussis toxin, an inhibitor of certain heterotrimeric G-proteins. Neurite outgrowth induced by trans- homophilic NCAM was unaffected by the peptides, whereas knockdown of NCAM completely abrogated ENFIN2- and ENFIN11-induced neuritogenesis. These observations suggest that ENFIN2 and ENFIN11 induce neurite outgrowth in an NCAM-dependent manner through G-protein-coupled signal transduction pathways. Thus, ENFIN2 and ENFIN11 may be valuable for exploring this particular type of NCAM-mediated signaling.     

节律性听觉刺激下的神经振荡同步化及其应用

大脑的感觉、情绪、认知等功能与其神经振荡模式有密切的联系。通过施加节律性刺激可以调控大脑的神经振荡模式,进而影响个体感受、情绪状态和认知功能等。与近年来常见的非侵入性电刺激和磁刺激相比,同样依赖于外部刺激输入的节律性感觉刺激具有成本低、易操作等优点,被认为是一种极具潜力的神经调控手段。本文以节律性听觉刺激为例,系统综述了不同类型的节律性听觉刺激如何影响大脑的神经振荡模式,进而影响相关状态和功能;并通过总结外部节律性听觉刺激对个体感知觉、情绪与认知功能的影响,讨论其生理机制和应用前景。     

Rhombomere formation and hind-brain crest cell migration from prorhombomeric origins in mouse embryos

Prior to rhombomere development, structures called prorhombomeres appear in the mammalian hindbrain. This study clarifies the developmental relationship between prorhombomeres and their descendent rhombomeres and hindbrain crest cells in mouse embryos by focal dye injections at various levels of prorhombomere A (proRhA), proRhB, and proRhC, as well as at their boundaries. ProRhA gives rise to two rhombomeres, rhombomeres 1 and 2 (r1 and r2), as well as to crest cells that migrate into the first pharyngeal arch, including the trigeminal ganglion. ProRhB develops into r3 and r4 and produces crest cells populating the second arch and acousticofacial ganglion. The anterior portion of proRhC gives rise to r5 and r6 and to crest cells migrating into the third pharyngeal arch and the IXth ganglion; its posterior portion develops into r7 and releases crest cells into the fourth pharyngeal arch region as well as the Xth ganglion. These results suggest that the boundaries between prorhombomeres serve as lineage restrictions for both hind-brain neuroepithelial cells and for segmental origins of crest cell populations in mouse embryos. The Hox code of the mouse head can be schematized in a much simpler way based on this prorhombomeric organization of the hind-brain, suggesting that prorhombomeres primarily underlie mammalian hind-brain segmentation.     

Cranial variation in European populations: a spatial autocorrelation study at three time periods

This study reports on spatial variation of 10 cranial variables in European populations at 3 time periods. Means for these variables, based on 137, 108, and 183 samples from the Early Medieval, Late Medieval, and Recent periods, were subjected to one-dimensional and directional spatial autocorrelation analyses. Significant spatial structure was found for most variables. It becomes more pronounced as time progresses. The spatial patterns are not strongly clinal. Correlograms based on distances computed from all variables are monotonic only to 900, 1,650, and 1,350 km for the three periods. Regional patterns are seen for most variables and become more structured and significant with time. There is little similarity among the correlograms of the variables at any one period and virtually none among periods. Inferences about spatial structure of these populations, based on spatial autocorrelation analysis, suggest a pattern dominated by migration, followed by expansion and admixture rather than selection or chance fluctuations. The patterns of morphometric change seem to reflect the patterns of linguistic change in these areas.     

基于神经网络的马尾松叶绿素含量高光谱估算模型

分析不同生长期的马尾松冠层反射光谱特征与相应叶绿素含量的相关关系.利用36个红边参数逐一筛选,最终确定7个与叶绿素含量相关性较高的红边参数作为光谱特征参数,分别应用逐步分析法与BP神经网络构建叶绿素含量的高光谱估算模型;同样,筛选出4个植被指数作为光谱特征参数,同时,将对原始光谱进行主成分分析降维后的前4个主成分作为BP神经网络的输入变量,分别应用逐步分析法与BP神经网络构建叶绿素含量的高光谱估算模型.结果表明: 将红边参数作为输入变量建立的逐步回归模型和BP神经网络模型的决定系数(R²)分别为0.5205、0.7253,均方根误差(RMSE)分别为0.1004、0.0848,相对误差分别为6.3%、5.7%.将植被指数作为输入变量建立的逐步回归模型和BP神经网络模型的R²分别为0.5392、0.7064,RMSE分别为0.0978、0.0871,相对误差分别为6.2%、6.0%.基于主成分分析的BP神经网络模型的预测效果最好,R²为0.7475,RMSE为0.0540,相对误差为4.8%.     

Rapid screening for metabolite overproduction in fermentor broths, using pyrolysis mass spectrometry with multivariate calibration and artificial neural networks

Binary mixtures of model systems consisting of the antibiotic ampicillin with either Escherichia coli or Staphylococcus auresu were subjected to pyrolysis mass spectrometry (PyMS). To deconvolute the pyrolysis mass spectra, so as to obtain quantitative information on the concentration of ampicilin in the mixtures, partial least squares regression (PLS), principal components regression (PCR), and fully interconnected feedforward artificial neural networks (ANNs) were studied. In the latter case, the weights were modified using the standard backpropagation algorithm, and the nodes used a sigmoidal squsahing funciton. It was found that each of the methods could be used to provide calibration models which gave excellent predictions for the concentrations of ampicillin in samples on which they had not been trained. Furthermore, ANNs trained to predict the amount of ampicilin in E. coli were able to generalise so as to predict the concentration of ampicillin in a S. aureus background, illustrating the robustness of ANNs to rather substantial variations in the biological background. The PyMS of the complex mixture of ampicilin in bacteria could not be expressed simply in terms of additive combinations of the spectra describing the pure components of the mixtures and their relative concentrations. Intermolecular reactions took place in the pyrolysate, leading to a lack of superposition of the spectral components and to a dependence of the normalized mass spectrum on sample size. Samples from fermentations of a single organism in a complex production medium were also analyzed quantitatively for a drug of commercial interest. The drug could also be quantified in a variety of mutant-producing strains cultivated in the same medium. The combination of PyMS and ANNs constitutes a novel, rapid, and convenient method for exploitation in strain improvement screening programs. (c) 1994 John Wiley & Sons, Inc.     

Integrin alpha5beta1 supports the migration of Xenopus cranial neural crest on fibronectin

During early embryonic development, cranial neural crest cells emerge from the developing mid- and hindbrain. While numerous studies have focused on integrin involvement in trunk neural crest cell migration, comparatively little is known about mechanisms of cranial neural crest cell migration. We show that fibronectin, but not laminin, vitronectin, or type I collagen can support cranial neural crest cell migration and segmentation in vitro. These behaviors require both the RGD and "synergy" sites located within the central cell-binding domain of fibronectin. While these two sites are sufficient for cranial neural crest cell migration, we find that the second Heparin-binding domain of fibronectin can provide additional support for cranial neural crest cell migration in vitro. Finally, using a function blocking monoclonal antibody, we show that cranial neural crest cell migration on fibronectin requires the integrin alpha5beta1.     

A gait index may underestimate changes of gait: a comparison of the Movement Deviation Profile and the Gait Deviation Index

The ability of the Movement Deviation Profile (MDP) and Gait Deviation Index (GDI) to detect gait changes was compared in a child with cerebral palsy who underwent game training. Conventional gait analysis showed that sagittal plane angles became mirrored about normality after training. Despite considerable gait changes, the GDI showed minimal change, while the MDP detected a difference equal to a shift between 10-9 on the Functional Assessment Questionnaire scale. Responses of the GDI and MDP were examined during a synthetic transition of the patient's curves from before intervention to a state mirrored about normality. The GDI showed a symmetric response on the two opposite sides of normality but the neural network based MDP gave an asymmetric response reflecting faithfully the unequal biomechanical consequences of joint angle changes. In conclusion, the MDP can detect altered gait even if the changes are missed by the GDI.