Simulation of Neural Behavior

The brain is an organ that takes the central role in advanced information processing. There exist great many neurons in our brain, which build complicated neural networks. All information processing in the brain is accomplished by neural activity in the form of neural oscillations. In order to understand the mechanisms of information processing, it is necessary to clarify functions of neurons and neural networks. Although the current progress of experiment technology is remarkable, only experiments by themselves cannot uncover the behavior of only a single neuron. Computational neuroscience is a research field, which fills up the deficiency in experiments. By modeling the essential features of a neuron or a neural network, we can analyze their fundamental properties by computer simulation. In this chapter, one aspect of computational neuroscience is described. At the first, the cell membrane and a neuron can be modeled by using an RC circuit. Next, the Hodgkin-Huxley model is introduced, which has the function of generation of action potentials. Furthermore, many neurons show the subthreshold resonance phenomena, and the cell membrane is necessary to be modeled by an RLC circuit. Finally, some simulation results are shown, and properties of such neuronal behaviors are discussed

Imbalanced expression of polycistronic miRNA in acute myeloid leukemia

miR-1 and miR-133 are clustered on the same chromosomal loci and are transcribed together as a single transcript that is positively regulated by ecotropic virus integration site-1 (EVI1). Previously, we described how miR-133 has anti-tumorigenic potential through repression of EVI1 expression. It has also been reported that miR-1 is oncogenic in the case of acute myeloid leukemia (AML). Here, we show that expression of miR-1 and miR-133, which have distinct functions, is differentially regulated between AML cell lines. Interestingly, the expression of miR-1 and EVI1, which binds to the promoter of the miR-1/miR-133 cluster, is correlative. The expression levels of TDP-43, an RNA-binding protein that has been reported to increase the expression, but inhibits the activity, of miR-1, were not correlated with expression levels of miR-1 in AML cells. Taken together, our observations raise the possibility that the balance of polycistronic miRNAs is regulated post-transcriptionally in a hierarchical manner possibly involving EVI1,suggesting that the deregulation of this balance may play some role in AML cells with high EVI1 expression

ヨード ゾウエイ ザイ ニヨル アナフィラキシー ショック ノ 3レイ : ブンケンテキ コウサツ

造影CT検査は悪性腫瘍の質的診断や病期診断,解離性動脈瘤の診断に欠かせない.しかし,ヨード造影剤で重篤な副作用が生じる危険性がある.気管支喘息など危険因子はいわれているものの,実際,副作用発現は予測不能である.今回,我々は,ここ8ヶ月の間にヨード造影剤による重篤なアナフィラキシーショックを生じた3例を経験したので文献的考察を加えて報告する.Recently, iodinated contrast media are necessary for CT examinations and they occupy an important position in the radiological diagnosis. Nonionic contrast media significantly reduce the prevalence of all degree of adverse reaction to contrast media rather than ionic contrast media. So, generally, iodinated contrast media are safe and widely used, but adverse reaction after intravenous iodinated contrast media are not uncommon. Severe and potentially life-threatening reaction occur by using the iodinated contrast media practically. Patients at risk must be identified before the contrast media study, and all possible measures must be taken to deal effectively with spontaneous anaphylactic reactions. We report three cases of anaphylactic reactions by iodinated contrast media on CT

Contribution of voltage-dependent ion channels to subthreshold resonance

Subthreshold resonance has been observed in many excitatory/'inhibitory neurons in the brain and it is suggested that such resonance phenomena play an important role in behavioral or perceptual functions in animals. Various voltage-dependent channels are thought to be involved in the generation of these resonance oscillations. For a compartmental neuron model with Ca2+-dependent K+ channel and low-threshold Ca2+ channel, conductance-based channel dynamics are linearized around equilibrium states and a neuron model can be treated as an equivalent RLC electric circuit, which indicates that the subthreshold resonance may be attributable to inductive properties of voltage-dependent channels. By computer simulation, we examine how parameters of these voltage-dependent channels, such as an equilibrium potential and the amplitude, effect to generate a subthreshold resonance

Mathematical Modeling of Subthreshold Resonant Properties in Pyloric Dilator Neurons

Various types of neurons exhibit subthreshold resonance oscillation (preferred frequency response) to fluctuating sinusoidal input currents. This phenomenon is well known to influence the synaptic plasticity and frequency of neural network oscillation. This study evaluates the resonant properties of pacemaker pyloric dilator (PD) neurons in the central pattern generator network through mathematical modeling. From the pharmacological point of view, calcium currents cannot be blocked in PD neurons without removing the calcium-dependent potassium current. Thus, the effects of calcium I Ca and calcium-dependent potassium I KCa currents on resonant properties remain unclear. By taking advantage of Hodgkin-Huxley-type model of neuron and its equivalent RLC circuit, we examine the effects of changing resting membrane potential and those ionic currents on the resonance. Results show that changing the resting membrane potential influences the amplitude and frequency of resonance so that the strength of resonance (Q-value) increases by both depolarization and hyperpolarization of the resting membrane potential. Moreover, hyperpolarization-activated inward current I h and I Ca (in association with I KCa) are dominant factors on resonant properties at hyperpolarized and depolarized potentials, respectively. Through mathematical analysis, results indicate that I h and I KCa affect the resonant properties of PD neurons. However, I Ca only has an amplifying effect on the resonance amplitude of these neurons

Study on histological properties of recellularized bioscaffolds from decellularized tissues for vessel regenerative application

The increasing number of arteries and organs needed for cardiovascular disease (CVD) patients with end-stage organ failure and bypass surgery has urge the need for future medical substituents. Transplantation provides an immediate treatment for the patients with end stage of organ failure by replacing tissues or organs with the normally function substitute. However, the need of immunosuppression and shortage of donors limit the impact of transplantation which then propel the evolution of tissue engineering. Recently, sonication decellularization technique is able to to prepare biological decellularized tissue efficiently. It has been established and proven by Azhim et al. and has successfully characterized some properties of the decellularized tissue scaffolds in the previous project (FRGS/1/2015/SG05/UIAM/02/6). However, its remaining research includes recellularized bioscaffolds properties evaluation and in-vitro cell infiltration and proliferation evaluations. It is hypothesized that recellularized bioscaffolds have fully seeded and infiltrated by autologous cells while producing new extracellular matrix (ECM) composition and providing sufficient biomechanical integrity of the ECM before implantation. In previous study, it has demonstrated that the decellularized tissues are able to prepare with lower toxicity level and significantly unchanged biomechanical strength. Henceforth, the objectives of this research are to investigate recellularization rate of the seeded cells onto/ into decellularized bioscaffolds which engineered by sonication decellularization system. The ECM integrity and cell removal of decellularized artery are confirmed by evaluation of histological HE staining, scanning electron microscopy and DNA quantitation. The recellularization of decellularized matrices are evaluated by measuring the coverage of the seeded endothelial cells on the matrices and their capability to infiltrate into the matrices using similar methods as described above. The outcome of this research could give an insight on the potential use of recellularized bioscaffolds in regenerative tissues/organs in future medicine

Identification of Indole Alkaloid Structural Units Important for Stimulus-Selective TRPM8 Inhibition: SAR Study of Naturally Occurring Iboga Derivatives

The iboga alkaloid voacangine (<b>1</b>) has been reported previously to be the first stimulus-selective TRPM8 antagonist. In the present report, a structure–activity relationship (SAR) study is described on the effects of some naturally occurring indole alkaloid analogues on TRPM8 inhibition. Dihydrocatharanthine (<b>10</b>) and catharanthine (<b>11</b>) were found to be inhibitors of TRPM8 activity, and their IC₅₀ values were equivalent to that of BCTC, a potent and representative TRPM8 antagonist. Furthermore, it was shown that the iboga moiety is the most crucial unit for TRPM8 blockade and that its stereostructure, as found in <b>1</b> but not in <b>10</b> and <b>11</b>, is essential for chemical agonist-selective TRPM8 inhibition. These findings should provide useful information for synthesizing additional stimulus-selective and TRPM8-selective blockers