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There are 27 papers published in subject: > since this site started. |
Results per page: | 27 Total, 3 Pages | << First < Previous 1 2 3 |
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1. First Spiking Dynamics of Stochastic Neuronal Model with Optimal Control | |||
Wu Yongjun | |||
Biology 23 February 2009 | |||
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Abstract:First-spiking dynamics of optimally controlled neuron under stimulation of colored noise is investigated. The stochastic averaging principle is utilized and the model equation is approximated by diffusion process and depicted by It?stochastic differential equation. The control problems for maximizing the resting probability and maximizing the time to first spike are constructed and the dynamical programming equations associated with the corresponding optimization problem are established. The optimal control law is determined. The corresponding backward Kolmogorov equation and Pontryagin equation are established and solved to yield the resting probability and the time to first spike. The analytical results are verified by Monte Carlo simulation. It has shown that the proposed control strategy can suppress the overactive neuronal firing activity and possesses potential application for some neural diseases treatment. | |||
TO cite this article:Wu Yongjun. First Spiking Dynamics of Stochastic Neuronal Model with Optimal Control[OL].[23 February 2009] http://en.paper.edu.cn/en_releasepaper/content/29445 |
2. Study on the Mechanism of the BtuF Periplasmic-binding Protein for Vitamin B12 | |||
Liu Ming,Sun TingGuang,Hu JianPing,Chen WeiZu,Wang CunXin | |||
Biology 05 March 2008 | |||
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Abstract:BtuF is the periplasmic binding protein (PBP) that binds vitamin B12 and delivers it to the periplasmic surface of the ABC transporter BtuCD. PBPs generally exhibit considerable conformational changes during ligand binding process, however, BtuF belongs to a subclass of PBPs that, doesn’t show such behavior on the basis of the crystal structures. Employing steered molecular dynamics on the B12-bound BtuF, we investigated the energetics and mechanism of BtuF. A potential of mean force along the postulated vitamin B12 unbinding pathway was constructed through Jarzynski’s equality. The large free energy differences of the postulated B12 unbinding process suggests the B12-bound structure is in a stable closed state and some conformation changes may be necessary to the B12 unbinding. From the result of the principal component analysis, we found the BtuF-B12 complex shows clear opening-closing and twisting motion tendencies which may facilitate the unbinding of B12 from the binding pocket. The intrinsic flexibility of BtuF was also explored, and it’s suggested the Trp44-Gln45 pair, which is situated at the mouth of the B12 binding pocket, may act as a gate in the B12 binding and unbinding process. | |||
TO cite this article:Liu Ming,Sun TingGuang,Hu JianPing, et al. Study on the Mechanism of the BtuF Periplasmic-binding Protein for Vitamin B12[OL].[ 5 March 2008] http://en.paper.edu.cn/en_releasepaper/content/19051 |
3. Study on topological properties of weighted conformation space using complex network | |||
Lai Zaizhi,Ji Guo SU,Wei Zu CHEN,Cun Xin WANG | |||
Biology 03 March 2008 | |||
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Abstract:The conformation space generated by a short two-dimensional lattice chain is mapped to a network. The conformations are the vertices of the network and the transitions between them are links. It has been found that this network has the “small-world” properties without considering the interaction energy of the monomer. To illustrate the influence of the interaction energy on the property of the conformation space network, the hydrophobic-polar lattice model was adopted and a method of weighting was proposed to study this network. When the weight based on the interaction energy of the monomer is added to the network, it is found that the weighted network shows the “scale-free” property. The result indicates that the weight is important for the topology of the conformation space network. | |||
TO cite this article:Lai Zaizhi,Ji Guo SU,Wei Zu CHEN, et al. Study on topological properties of weighted conformation space using complex network [OL].[ 3 March 2008] http://en.paper.edu.cn/en_releasepaper/content/18961 |
4. Loading Trehalose into Red Blood Cells by Improved Hypotonic Method | |||
Zhou Xinli,He Hui,Liu Bqolin,Hua ZeZhao | |||
Biology 31 January 2008 | |||
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Abstract:As a first step toward RBCs long-term preservation by freeze-drying, we present an improved hypotonic method for loading RBCs with trehalose. The method is based on the osmotic pressure difference and concentration difference between the inside and the outside of the RBCs. The RBCs are dehydrated in hypertonic glucose solutions to increase the osmotic pressure inside the cells, and then incubated in hypotonic trehalose solutions to allow trehalose to enter into RBCs. The data showed that trehalose uptake by RBCs increased with osmotic pressure difference across the cell membrane, 43.2mM intracellular trehalose was observed when osmotic pressure difference reached 1369.8mOsm/L. Hematology analysis indicated that RBCs shrank in hypertonic glucose solution and swelled in hypotonic trehalose solution, resulting in a few release of cytoplasmic hemoglobin. The level of ATP in trehalose-loaded RBCs recovered to normal value after 4h incubation. Osmotic fragility data showed that trehalose-loaded RBCs are osmotically stable after dehydration and loading processes. | |||
TO cite this article:Zhou Xinli,He Hui,Liu Bqolin, et al. Loading Trehalose into Red Blood Cells by Improved Hypotonic Method[OL].[31 January 2008] http://en.paper.edu.cn/en_releasepaper/content/18527 |
5. An improved predictive assay for radiotherapy to human hepatoma measured by prematurely chromosome condensation technique | |||
Yang Jianshe | |||
Biology 28 December 2005 | |||
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Abstract:To investigate the radiation response of hepatoma, SMMC-7721 cells were irradiated with 60Co γ-rays. Initial chromatid breaks were measured by counting the number of chromatid breaks and isochromatid breaks. A dose-dependent increase in radiation-induced chromatid/isochromatid breaks was observed in G1 and G2 phase respectively. A good relationship was found between cell survival and chromatin breaks. This study implied that low LET radiation-induced chromatid/isochromatid breaks can be possibly used as a good predictor of radiosensitivity of SMMC-7721 hepatoma cells. | |||
TO cite this article:Yang Jianshe. An improved predictive assay for radiotherapy to human hepatoma measured by prematurely chromosome condensation technique[OL].[28 December 2005] http://en.paper.edu.cn/en_releasepaper/content/4728 |
6. Visualization of dynamic correlation among neuron population | |||
Yi Zhou,Ai-hua Chen,Xin Jin,Pei-Ji Liang | |||
Biology 21 December 2005 | |||
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Abstract:A method for visualization of dynamic correlations among multi-neurons is introduced here. Dynamic correlations of multi neurons can be displayed in a simple and clear manner. The correlation histogram and the conventional gravity transform are presented to compare with this approved method. Simulated spike trains based on an I-F model were used for evaluation. | |||
TO cite this article:Yi Zhou,Ai-hua Chen,Xin Jin, et al. Visualization of dynamic correlation among neuron population[OL].[21 December 2005] http://en.paper.edu.cn/en_releasepaper/content/4526 |
7. Reparatory Effects of Nicotine on NMDA Receptor-mediated Synaptic Plasticity in the Hippocampal CA1 Region of Chronically Lead-exposed Rats | |||
Wang Huili,Ruan Di-yun | |||
Biology 05 December 2005 | |||
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Abstract:Activation of neuronal nicotinic acetylcholine receptors (nAChRs) modulates the induction of long-term potentiation (LTP), one of the possible cellular mechanisms for learning. To investigate the effect of nicotine on synaptic plasticity in chronically lead-exposed rats, field excitatory postsynaptic potentials (fEPSPs) and paired-pulse facilitation (PPF) were recorded in the CA1 area of hippocampal slices from chronically lead-exposed rats of 23-30 days old. The results showed that: (1) 1μM nicotine facilitated the induction of LTP in CA1 area of the hippocampus by a weak tetanic stimulation (100 Hz, 20 Pulses), which does not by itself produce LTP in lead-exposed rats. This effect was significantly suppressed by mecamylamine (MEC), a nonselective nicotinic antagonist, suggesting that the facilitation of LTP was through nAChRs. (2) The nicotine-mediated LTP was blocked by dihydro-β-erythroidine (DhβE), a non-α7 nAChR antagonist, while long-term depression (LTD) produced by the combination of nicotine and methyllycaconitine (MLA), a α7-nAChR antagonist and neither LTP nor LTD observed by the combination of nicotine, MLA and DHβE. It implied that several nAChRs subtypes were involved in the nicotine-mediated synaptic plasticity. (3) Nicotine enhanced PPF in hippocampal CA1 region, and the nicotine-mediated LTP in lead-exposed rats was blocked by either D-(-)-2-amino-5-phosphonopentanoic acid (D-AP5), the NMDAs receptor antagonist, or picrotoxin (PTX), an antagonist of γ-aminobutyric acid (GABA)A receptor. It suggested that nicotine-mediated synaptic plasticity was due to the activation of NMDARs by disinhibition of pyramidal cells through presynaptic nAChRs. This may represent the cellular basis of nicotine-mediated cognitive enhancement observed in chronically lead-exposed rats. | |||
TO cite this article:Wang Huili,Ruan Di-yun. Reparatory Effects of Nicotine on NMDA Receptor-mediated Synaptic Plasticity in the Hippocampal CA1 Region of Chronically Lead-exposed Rats[OL].[ 5 December 2005] http://en.paper.edu.cn/en_releasepaper/content/4077 |
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