Sample records for purkinje cell model

  1. The 40-year history of modeling active dendrites in cerebellar Purkinje cells: Emergence of the first single cell 'Community Model'

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    James M Bower


    Full Text Available The subject of the effects of the active properties of the Purkinje cell dendrite on neuronal function has been an active subject of study for more than 40 years. Somewhat unusually, some of these investigations, from the outset have involved an interacting combination of experimental and model-based techniques. This paper recounts that 40-year history, and the view of the functional significance of the active properties of the Purkinje cell dendrite that has emerged. It specifically considers the emergence from these efforts of what is arguably the first single cell ‘community’ model in neuroscience. The paper also considers the implications of the development of this model for future studies of the complex properties of neuronal dendrites.

  2. Increased protein kinase C gamma activity induces Purkinje cell pathology in a mouse model of spinocerebellar ataxia 14. (United States)

    Ji, Jingmin; Hassler, Melanie L; Shimobayashi, Etsuko; Paka, Nagendher; Streit, Raphael; Kapfhammer, Josef P


    Spinocerebellar ataxias (SCAs) are hereditary diseases leading to Purkinje cell degeneration and cerebellar dysfunction. Most forms of SCA are caused by expansion of CAG repeats similar to other polyglutamine disorders such as Huntington's disease. In contrast, in the autosomal dominant SCA-14 the disease is caused by mutations in the protein kinase C gamma (PKCγ) gene which is a well characterized signaling molecule in cerebellar Purkinje cells. The study of SCA-14, therefore, offers the unique opportunity to reveal the molecular and pathological mechanism eventually leading to Purkinje cell dysfunction and degeneration. We have created a mouse model of SCA-14 in which PKCγ protein with a mutation found in SCA-14 is specifically expressed in cerebellar Purkinje cells. We find that in mice expressing the mutated PKCγ protein the morphology of Purkinje cells in cerebellar slice cultures is drastically altered and mimics closely the morphology seen after pharmacological PKC activation. Similar morphological abnormalities were seen in localized areas of the cerebellum of juvenile transgenic mice in vivo. In adult transgenic mice there is evidence for some localized loss of Purkinje cells but there is no overall cerebellar atrophy. Transgenic mice show a mild cerebellar ataxia revealed by testing on the rotarod and on the walking beam. Our findings provide evidence for both an increased PKCγ activity in Purkinje cells in vivo and for pathological changes typical for cerebellar disease thus linking the increased and dysregulated activity of PKCγ tightly to the development of cerebellar disease in SCA-14 and possibly also in other forms of SCA.

  3. Parallel fiber to Purkinje cell synaptic impairment in a mouse model of spinocerebellar ataxia type 27

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    Filippo eTempia


    Full Text Available Genetically inherited mutations in the fibroblast growth factor 14 (FGF14 gene lead to spinocerebellar ataxia type 27 (SCA27, an autosomal dominant disorder characterized by severe heterogeneous motor and cognitive impairments. Consistently, genetic deletion of Fgf14 in Fgf14-/- mice recapitulates salient features of the SCA27 human disease. In vitro molecular studies in cultured neurons indicate that the FGF14F145S SCA27 allele acts as a dominant negative mutant suppressing the FGF14 wild type function and resulting in inhibition of voltage-gated Na+ and Ca2+ channels. To gain insights in the cerebellar deficits in the animal model of the human disease, we applied whole-cell voltage-clamp in the acute cerebellar slice preparation to examine the properties of parallel fibers (PF to Purkinje neuron synapses in Fgf14-/- mice and wild type littermates. We found that the AMPA receptor-mediated excitatory postsynaptic currents evoked by PF stimulation (PF-EPSCs were significantly reduced in Fgf14-/- animals, while short-term plasticity, measured as paired-pulse facilitation (PPF, was enhanced. Measuring Sr2+-induced release of quanta from stimulated synapses, we found that the size of the PF-EPSCs was unchanged, ruling out a postsynaptic deficit. This phenotype was corroborated by decreased expression of VGLUT1, a specific presynaptic marker at PF-Purkinje neuron synapses. We next examined the mGluR1 receptor-induced response (mGluR1-EPSC that under normal conditions requires a gradual build-up of glutamate concentration in the synaptic cleft, and found no changes in these responses in Fgf14-/- mice. These results provide evidence of a critical role of FGF14 in maintaining presynaptic function at PF-Purkinje neuron synapses highlighting critical target mechanisms to recapitulate the complexity of the SCA27 disease.

  4. Mapping the development of cerebellar Purkinje cells in zebrafish. (United States)

    Hamling, Kyla R; Tobias, Zachary J C; Weissman, Tamily A


    The cells that comprise the cerebellum perform a complex integration of neural inputs to influence motor control and coordination. The functioning of this circuit depends upon Purkinje cells and other cerebellar neurons forming in the precise place and time during development. Zebrafish provide a useful platform for modeling disease and studying gene function, thus a quantitative metric of normal zebrafish cerebellar development is key for understanding how gene mutations affect the cerebellum. To begin to quantitatively measure cerebellar development in zebrafish, we have characterized the spatial and temporal patterning of Purkinje cells during the first 2 weeks of development. Differentiated Purkinje cells first emerged by 2.8 days post fertilization and were spatially patterned into separate dorsomedial and ventrolateral clusters that merged at around 4 days. Quantification of the Purkinje cell layer revealed that there was a logarithmic increase in both Purkinje cell number as well as overall volume during the first 2 weeks, while the entire region curved forward in an anterior, then ventral direction. Purkinje cell dendrites were positioned next to parallel fibers as early as 3.3 days, and Purkinje cell diameter decreased significantly from 3.3 to 14 days, possibly due to cytoplasmic reappropriation into maturing dendritic arbors. A nearest neighbor analysis showed that Purkinje cells moved slightly apart from each other from 3 to 14 days, perhaps spreading as the organized monolayer forms. This study establishes a quantitative spatiotemporal map of Purkinje cell development in zebrafish that provides an important metric for studies of cerebellar development and disease.

  5. A cell model study of calcium influx mechanism regulated by calcium-dependent potassium channels in Purkinje cell dendrites. (United States)

    Chono, Koji; Takagi, Hiroshi; Koyama, Shozo; Suzuki, Hideo; Ito, Etsuro


    The present study was designed to elucidate the roles of dendritic voltage-gated K+ channels in Ca2+ influx mechanism of a rat Purkinje cell using a computer simulation program. First, we improved the channel descriptions and the maximum conductance in the Purkinje cell model to mimic both the kinetics of ion channels and the Ca2+ spikes, which had failed in previous studies. Our cell model is, therefore, much more authentic than those in previous studies. Second, synaptic inputs that mimic stimulation of parallel fibers and induce sub-threshold excitability were simultaneously applied to the spiny dendrites. As a result, transient Ca2+ responses were observed in the stimulation points and they decreased with the faster decay rate in the cell model including high-threshold Ca2+-dependent K+ channels than in those excluding these channels. Third, when a single synaptic input was applied into a spiny dendrite, Ca2+-dependent K+ channels suppressed Ca2+ increases at stimulation and recording points. Finally, Ca2+-dependent K+ channels were also found to suppress the time to peak Ca2+ values in the recording points. These results suggest that the opening of Ca2+-dependent K+ channels by Ca2+ influx through voltage-gated Ca2+ channels hyperpolarizes the membrane potentials and deactivates these Ca2+ channels in a negative feedback manner, resulting in local, weak Ca2+ responses in spiny dendrites of Purkinje cells.

  6. A spiking network model of cerebellar Purkinje cells and molecular layer interneurons exhibiting irregular firing

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    William eLennon


    Full Text Available While the anatomy of the cerebellar microcircuit is well studied, how it implements cerebellar function is not understood. A number of models have been proposed to describe this mechanism but few emphasize the role of the vast network Purkinje cells (PKJs form with the molecular layer interneurons (MLIs – the stellate and basket cells. We propose a model of the MLI-PKJ network composed of simple spiking neurons incorporating the major anatomical and physiological features. In computer simulations, the model reproduces the irregular firing patterns observed in PKJs and MLIs in vitro and a shift toward faster, more regular firing patterns when inhibitory synaptic currents are blocked. In the model, the time between PKJ spikes is shown to be proportional to the amount of feedforward inhibition from an MLI on average. The two key elements of the model are: (1 spontaneously active PKJs and MLIs due to an endogenous depolarizing current, and (2 adherence to known anatomical connectivity along a parasagittal strip of cerebellar cortex. We propose this model to extend previous spiking network models of the cerebellum and for further computational investigation into the role of irregular firing and MLIs in cerebellar learning and function.

  7. Purkinje cell activity during classical conditioning with different conditional stimuli explains central tenet of Rescorla–Wagner model [corrected]. (United States)

    Rasmussen, Anders; Zucca, Riccardo; Johansson, Fredrik; Jirenhed, Dan-Anders; Hesslow, Germund


    A central tenet of Rescorla and Wagner's model of associative learning is that the reinforcement value of a paired trial diminishes as the associative strength between the presented stimuli increases. Despite its fundamental importance to behavioral sciences, the neural mechanisms underlying the model have not been fully explored. Here, we present findings that, taken together, can explain why a stronger association leads to a reduced reinforcement value, within the context of eyeblink conditioning. Specifically, we show that learned pause responses in Purkinje cells, which trigger adaptively timed conditioned eyeblinks, suppress the unconditional stimulus (US) signal in a graded manner. Furthermore, by examining how Purkinje cells respond to two distinct conditional stimuli and to a compound stimulus, we provide evidence that could potentially help explain the somewhat counterintuitive overexpectation phenomenon, which was derived from the Rescorla-Wagner model.

  8. Downregulation of the Glial GLT1 Glutamate Transporter and Purkinje Cell Dysfunction in a Mouse Model of Myotonic Dystrophy

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    Géraldine Sicot


    Full Text Available Brain function is compromised in myotonic dystrophy type 1 (DM1, but the underlying mechanisms are not fully understood. To gain insight into the cellular and molecular pathways primarily affected, we studied a mouse model of DM1 and brains of adult patients. We found pronounced RNA toxicity in the Bergmann glia of the cerebellum, in association with abnormal Purkinje cell firing and fine motor incoordination in DM1 mice. A global proteomics approach revealed downregulation of the GLT1 glutamate transporter in DM1 mice and human patients, which we found to be the result of MBNL1 inactivation. GLT1 downregulation in DM1 astrocytes increases glutamate neurotoxicity and is detrimental to neurons. Finally, we demonstrated that the upregulation of GLT1 corrected Purkinje cell firing and motor incoordination in DM1 mice. Our findings show that glial defects are critical in DM1 brain pathophysiology and open promising therapeutic perspectives through the modulation of glutamate levels.

  9. Action potential processing in a detailed Purkinje cell model reveals a critical role for axonal compartmentalization

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    Stefano eMasoli


    Full Text Available The Purkinje cell (PC is among the most complex neurons in the brain and plays a critical role for cerebellar functioning. PCs operate as fast pacemakers modulated by synaptic inputs but can switch from simple spikes to complex bursts and, in some conditions, show bistability. In contrast to original works emphasizing dendritic Ca-dependent mechanisms, recent experiments have supported a primary role for axonal Na-dependent processing, which could effectively regulate spike generation and transmission to deep cerebellar nuclei (DCN. In order to account for the numerous ionic mechanisms involved (at present including Nav1.6, Cav2.1, Cav3.1, Cav3.2, Cav3.3, Kv1.1, Kv1.5, Kv3.3, Kv3.4, Kv4.3, KCa1.1, KCa2.2, KCa3.1, Kir2.x, HCN1, we have elaborated a multicompartmental model incorporating available knowledge on localization and gating of PC ionic channels. The axon, including initial segment (AIS and Ranvier nodes (RNs, proved critical to obtain appropriate pacemaking and firing frequency modulation. Simple spikes initiated in the AIS and protracted discharges were stabilized in the soma through Na-dependent mechanisms, while somato-dendritic Ca channels contributed to sustain pacemaking and to generate complex bursting at high discharge regimes. Bistability occurred only following Na and Ca channel down-regulation. In addition, specific properties in RNs K currents were required to limit spike transmission frequency along the axon. The model showed how organized electroresponsive functions could emerge from the molecular complexity of PCs and showed that the axon is fundamental to complement ionic channel compartmentalization enabling action potential processing and transmission of specific spike patterns to DCN.

  10. Ataxia with loss of Purkinje cells in a mouse model for Refsum disease. (United States)

    Ferdinandusse, Sacha; Zomer, Anna W M; Komen, Jasper C; van den Brink, Christina E; Thanos, Melissa; Hamers, Frank P T; Wanders, Ronald J A; van der Saag, Paul T; Poll-The, Bwee Tien; Brites, Pedro


    Refsum disease is caused by a deficiency of phytanoyl-CoA hydroxylase (PHYH), the first enzyme of the peroxisomal alpha-oxidation system, resulting in the accumulation of the branched-chain fatty acid phytanic acid. The main clinical symptoms are polyneuropathy, cerebellar ataxia, and retinitis pigmentosa. To study the pathogenesis of Refsum disease, we generated and characterized a Phyh knockout mouse. We studied the pathological effects of phytanic acid accumulation in Phyh(-/-) mice fed a diet supplemented with phytol, the precursor of phytanic acid. Phytanic acid accumulation caused a reduction in body weight, hepatic steatosis, and testicular atrophy with loss of spermatogonia. Phenotype assessment using the SHIRPA protocol and subsequent automated gait analysis using the CatWalk system revealed unsteady gait with strongly reduced paw print area for both fore- and hindpaws and reduced base of support for the hindpaws. Histochemical analyses in the CNS showed astrocytosis and up-regulation of calcium-binding proteins. In addition, a loss of Purkinje cells in the cerebellum was observed. No demyelination was present in the CNS. Motor nerve conduction velocity measurements revealed a peripheral neuropathy. Our results show that, in the mouse, high phytanic acid levels cause a peripheral neuropathy and ataxia with loss of Purkinje cells. These findings provide important insights in the pathophysiology of Refsum disease.

  11. Physiology, morphology and detailed passive models of guinea-pig cerebellar Purkinje cells. (United States)

    Rapp, M; Segev, I; Yarom, Y


    1. Purkinje cells (PCs) from guinea-pig cerebellar slices were physiologically characterized using intracellular techniques. Extracellular caesium ions were used to linearize the membrane properties of PCs near the resting potential. Under these conditions the average input resistance, RN, was 29 M omega, the average system time constant, tau 0, was 82 ms and the average cable length, LN, was 0.59. 2. Three PCs were fully reconstructed following physiological measurements and staining with horseradish peroxidase. Assuming that each spine has an area of 1 micron 2 and that the spine density over the spiny dendrites is ten spines per micrometre length, the total membrane area of each PC is approximately 150,000 microns 2, of which approximately 100,000 microns 2 is in the spines. 3. Detailed passive cable and compartmental models were built for each of the three reconstructed PCs. Computational methods were devised to incorporate globally the huge number of spines into these models. In all three cells the models predict that the specific membrane resistivity, Rm, of the soma is much lower than the dendritic Rm (approximately 500 and approximately 100,000 omega cm2 respectively). The specific membrane capacitance, Cm, is estimated to be 1.5-2 muF cm-2 and the specific cytoplasm resistivity, Ri, is 250 omega cm. 4. The average cable length of the dendrites according to the model is 0.13 lambda, suggesting that under caesium conditions PCs are electrically very compact. Brief somatic spikes, however, are expected to attenuate 30-fold when spreading passively into the dendritic terminals. A simulated 200 Hz train of fast, 90 mV somatic spikes produced a smooth 12 mV steady depolarization at the dendritic terminals. 5. A transient synaptic conductance increase, with a 1 nS peak at 0.5 ms and a driving force of 60 mV, is expected to produce approximately 20 mV peak depolarization at the spine head membrane. This EPSP then attenuates between 200- and 900-fold into the soma

  12. Encoding of whisker input by cerebellar Purkinje cells (United States)

    Bosman, Laurens W J; Koekkoek, Sebastiaan K E; Shapiro, Joël; Rijken, Bianca F M; Zandstra, Froukje; van der Ende, Barry; Owens, Cullen B; Potters, Jan-Willem; de Gruijl, Jornt R; Ruigrok, Tom J H; De Zeeuw, Chris I


    The cerebellar cortex is crucial for sensorimotor integration. Sensorimotor inputs converge on cerebellar Purkinje cells via two afferent pathways: the climbing fibre pathway triggering complex spikes, and the mossy fibre–parallel fibre pathway, modulating the simple spike activities of Purkinje cells. We used, for the first time, the mouse whisker system as a model system to study the encoding of somatosensory input by Purkinje cells. We show that most Purkinje cells in ipsilateral crus 1 and crus 2 of awake mice respond to whisker stimulation with complex spike and/or simple spike responses. Single-whisker stimulation in anaesthetised mice revealed that the receptive fields of complex spike and simple spike responses were strikingly different. Complex spike responses, which proved to be sensitive to the amplitude, speed and direction of whisker movement, were evoked by only one or a few whiskers. Simple spike responses, which were not affected by the direction of movement, could be evoked by many individual whiskers. The receptive fields of Purkinje cells were largely intermingled, and we suggest that this facilitates the rapid integration of sensory inputs from different sources. Furthermore, we describe that individual Purkinje cells, at least under anaesthesia, may be bound in two functional ensembles based on the receptive fields and the synchrony of the complex spike and simple spike responses. The ‘complex spike ensembles’ were oriented in the sagittal plane, following the anatomical organization of the climbing fibres, while the ‘simple spike ensembles’ were oriented in the transversal plane, as are the beams of parallel fibres. PMID:20724365

  13. Heat Shock Protein Beta-1 Modifies Anterior to Posterior Purkinje Cell Vulnerability in a Mouse Model of Niemann-Pick Type C Disease.

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    Chan Chung


    Full Text Available Selective neuronal vulnerability is characteristic of most degenerative disorders of the CNS, yet mechanisms underlying this phenomenon remain poorly characterized. Many forms of cerebellar degeneration exhibit an anterior-to-posterior gradient of Purkinje cell loss including Niemann-Pick type C1 (NPC disease, a lysosomal storage disorder characterized by progressive neurological deficits that often begin in childhood. Here, we sought to identify candidate genes underlying vulnerability of Purkinje cells in anterior cerebellar lobules using data freely available in the Allen Brain Atlas. This approach led to the identification of 16 candidate neuroprotective or susceptibility genes. We demonstrate that one candidate gene, heat shock protein beta-1 (HSPB1, promoted neuronal survival in cellular models of NPC disease through a mechanism that involved inhibition of apoptosis. Additionally, we show that over-expression of wild type HSPB1 or a phosphomimetic mutant in NPC mice slowed the progression of motor impairment and diminished cerebellar Purkinje cell loss. We confirmed the modulatory effect of Hspb1 on Purkinje cell degeneration in vivo, as knockdown by Hspb1 shRNA significantly enhanced neuron loss. These results suggest that strategies to promote HSPB1 activity may slow the rate of cerebellar degeneration in NPC disease and highlight the use of bioinformatics tools to uncover pathways leading to neuronal protection in neurodegenerative disorders.

  14. Dendritic differentiation of cerebellar Purkinje cells is promoted by ryanodine receptors expressed by Purkinje and granule cells. (United States)

    Ohashi, Ryo; Sakata, Shin-ichi; Naito, Asami; Hirashima, Naohide; Tanaka, Masahiko


    Cerebellar Purkinje cells have the most elaborate dendritic trees among neurons in the brain. We examined the roles of ryanodine receptor (RyR), an intracellular Ca(2+) release channel, in the dendrite formation of Purkinje cells using cerebellar cell cultures. In the cerebellum, Purkinje cells express RyR1 and RyR2, whereas granule cells express RyR2. When ryanodine (10 µM), a blocker of RyR, was added to the culture medium, the elongation and branching of Purkinje cell dendrites were markedly inhibited. When we transferred small interfering RNA (siRNA) against RyR1 into Purkinje cells using single-cell electroporation, dendritic branching but not elongation of the electroporated Purkinje cells was inhibited. On the other hand, transfection of RyR2 siRNA into granule cells also inhibited dendritic branching of Purkinje cells. Furthermore, ryanodine reduced the levels of brain-derived neurotrophic factor (BDNF) in the culture medium. The ryanodine-induced inhibition of dendritic differentiation was partially rescued when BDNF was exogenously added to the culture medium in addition to ryanodine. Overall, these results suggest that RyRs expressed by both Purkinje and granule cells play important roles in promoting the dendritic differentiation of Purkinje cells and that RyR2 expressed by granule cells is involved in the secretion of BDNF from granule cells.

  15. The analysis of purkinje cell dendritic morphology in organotypic slice cultures. (United States)

    Kapfhammer, Josef P; Gugger, Olivia S


    Purkinje cells are an attractive model system for studying dendritic development, because they have an impressive dendritic tree which is strictly oriented in the sagittal plane and develops mostly in the postnatal period in small rodents (3). Furthermore, several antibodies are available which selectively and intensively label Purkinje cells including all processes, with anti-Calbindin D28K being the most widely used. For viewing of dendrites in living cells, mice expressing EGFP selectively in Purkinje cells (11) are available through Jackson labs. Organotypic cerebellar slice cultures cells allow easy experimental manipulation of Purkinje cell dendritic development because most of the dendritic expansion of the Purkinje cell dendritic tree is actually taking place during the culture period (4). We present here a short, reliable and easy protocol for viewing and analyzing the dendritic morphology of Purkinje cells grown in organotypic cerebellar slice cultures. For many purposes, a quantitative evaluation of the Purkinje cell dendritic tree is desirable. We focus here on two parameters, dendritic tree size and branch point numbers, which can be rapidly and easily determined from anti-calbindin stained cerebellar slice cultures. These two parameters yield a reliable and sensitive measure of changes of the Purkinje cell dendritic tree. Using the example of treatments with the protein kinase C (PKC) activator PMA and the metabotropic glutamate receptor 1 (mGluR1) we demonstrate how differences in the dendritic development are visualized and quantitatively assessed. The combination of the presence of an extensive dendritic tree, selective and intense immunostaining methods, organotypic slice cultures which cover the period of dendritic growth and a mouse model with Purkinje cell specific EGFP expression make Purkinje cells a powerful model system for revealing the mechanisms of dendritic development.

  16. Remodeling of monoplanar Purkinje cell dendrites during cerebellar circuit formation.

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    Megumi Kaneko

    Full Text Available Dendrite arborization patterns are critical determinants of neuronal connectivity and integration. Planar and highly branched dendrites of the cerebellar Purkinje cell receive specific topographical projections from two major afferent pathways; a single climbing fiber axon from the inferior olive that extend along Purkinje dendrites, and parallel fiber axons of granule cells that contact vertically to the plane of dendrites. It has been believed that murine Purkinje cell dendrites extend in a single parasagittal plane in the molecular layer after the cell polarity is determined during the early postnatal development. By three-dimensional confocal analysis of growing Purkinje cells, we observed that mouse Purkinje cells underwent dynamic dendritic remodeling during circuit maturation in the third postnatal week. After dendrites were polarized and flattened in the early second postnatal week, dendritic arbors gradually expanded in multiple sagittal planes in the molecular layer by intensive growth and branching by the third postnatal week. Dendrites then became confined to a single plane in the fourth postnatal week. Multiplanar Purkinje cells in the third week were often associated by ectopic climbing fibers innervating nearby Purkinje cells in distinct sagittal planes. The mature monoplanar arborization was disrupted in mutant mice with abnormal Purkinje cell connectivity and motor discoordination. The dendrite remodeling was also impaired by pharmacological disruption of normal afferent activity during the second or third postnatal week. Our results suggest that the monoplanar arborization of Purkinje cells is coupled with functional development of the cerebellar circuitry.

  17. Image-Based Structural Modeling of the Cardiac Purkinje Network

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    Benjamin R. Liu


    Full Text Available The Purkinje network is a specialized conduction system within the heart that ensures the proper activation of the ventricles to produce effective contraction. Its role during ventricular arrhythmias is less clear, but some experimental studies have suggested that the Purkinje network may significantly affect the genesis and maintenance of ventricular arrhythmias. Despite its importance, few structural models of the Purkinje network have been developed, primarily because current physical limitations prevent examination of the intact Purkinje network. In previous modeling efforts Purkinje-like structures have been developed through either automated or hand-drawn procedures, but these networks have been created according to general principles rather than based on real networks. To allow for greater realism in Purkinje structural models, we present a method for creating three-dimensional Purkinje networks based directly on imaging data. Our approach uses Purkinje network structures extracted from photographs of dissected ventricles and projects these flat networks onto realistic endocardial surfaces. Using this method, we create models for the combined ventricle-Purkinje system that can fully activate the ventricles through a stimulus delivered to the Purkinje network and can produce simulated activation sequences that match experimental observations. The combined models have the potential to help elucidate Purkinje network contributions during ventricular arrhythmias.

  18. The AMPA antagonist, NBQX, protects against ischemia-induced loss of cerebellar Purkinje cells

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    Balchen, T.; Diemer, Nils Henrik


    Neuropathology, NBQX, AMPA antagonist, cerebellar cells, ischemia, rats, Purkinje, neuronal death......Neuropathology, NBQX, AMPA antagonist, cerebellar cells, ischemia, rats, Purkinje, neuronal death...

  19. Dendritic planarity of Purkinje cells is independent of Reelin signaling. (United States)

    Kim, Jinkyung; Park, Tae-Ju; Kwon, Namseop; Lee, Dongmyeong; Kim, Seunghwan; Kohmura, Yoshiki; Ishikawa, Tetsuya; Kim, Kyong-Tai; Curran, Tom; Je, Jung Ho


    The dendritic planarity of Purkinje cells is critical for cerebellar circuit formation. In the absence of Crk and CrkL, the Reelin pathway does not function resulting in partial Purkinje cell migration and defective dendritogenesis. However, the relationships among Purkinje cell migration, dendritic development and Reelin signaling have not been clearly delineated. Here, we use synchrotron X-ray microscopy to obtain 3-D images of Golgi-stained Purkinje cell dendrites. Purkinje cells that failed to migrate completely exhibited conical dendrites with abnormal 3-D arborization and reduced dendritic complexity. Furthermore, their spines were fewer in number with a distorted morphology. In contrast, Purkinje cells that migrated successfully displayed planar dendritic and spine morphologies similar to normal cells, despite reduced dendritic complexity. These results indicate that, during cerebellar formation, Purkinje cells migrate into an environment that supports development of dendritic planarity and spine formation. While Reelin signaling is important for the migration process, it does not make a direct major contribution to dendrite formation.

  20. The Analysis of Purkinje Cell Dendritic Morphology in Organotypic Slice Cultures


    Kapfhammer, Josef P.; Gugger, Olivia S.


    Purkinje cells are an attractive model system for studying dendritic development, because they have an impressive dendritic tree which is strictly oriented in the sagittal plane and develops mostly in the postnatal period in small rodents 3. Furthermore, several antibodies are available which selectively and intensively label Purkinje cells including all processes, with anti-Calbindin D28K being the most widely used. For viewing of dendrites in living cells, mice expressing EGFP selectively i...

  1. The developmental loss of the ability of Purkinje cells to regenerate their axons occurs in the absence of myelin: an in vitro model to prevent myelination. (United States)

    Bouslama-Oueghlani, Lamia; Wehrlé, Rosine; Sotelo, Constantino; Dusart, Isabelle


    Axonal regeneration in the mammalian CNS is a property of immature neurons that is lost during development. Using organotypic culture of cerebellum, we have shown that in vitro Purkinje cells lose their regenerative capacity in parallel with the process of myelination. We have investigated whether myelination is involved in the age-dependent loss of regeneration of these neurons. By applying a high dose of bromodeoxyuridine in the culture medium of newborn cerebellar slices during the first 3 d in vitro, we have succeeded in obtaining cultures with oligodendrocyte depletion, together with a lack of ameboid microglia and enhancement of Purkinje cell survival. These cultures, after 14 d in vitro, are completely devoid of myelin. We have compared the ability of Purkinje cells to regenerate their axons in the presence or absence of myelin. Purkinje cells in cerebellar explants taken at birth, treated with bromodeoxyuridine and axotomized after 7 d in vitro, survive better than similar neurons in untreated cultures. However, despite the lack of myelin and the enhanced survival, Purkinje cells do not regenerate, whereas they do regenerate when the axotomy is done at postnatal day 0. Thus, the Purkinje cell developmental switch from axonal regeneration to lack of regeneration does not appear to be regulated by myelin.

  2. The role of Cbln1 on Purkinje cell synapse formation. (United States)

    Ito-Ishida, Aya; Okabe, Shigeo; Yuzaki, Michisuke


    Cbln1 is a glycoprotein which belongs to the C1q family. In the cerebellum, Cbln1 is produced and secreted from granule cells and works as a strong synapse organizer between Purkinje cells and parallel fibers, the axons of the granule cells. In this update article, we will describe the molecular mechanisms by which Cbln1 induces synapse formation and will review our findings on the axonal structural changes which occur specifically during this process. We will also describe our recent finding that Cbln1 has a suppressive role in inhibitory synapse formation between Purkinje cells and molecular layer interneurons. Our results have revealed that Cbln1 plays an essential role to establish parallel fiber-Purkinje cell synapses and to regulate balance between excitatory and inhibitory input on Purkinje cells.

  3. Purkinje cell intrinsic excitability increases after synaptic long term depression. (United States)

    Yang, Zhen; Santamaria, Fidel


    Coding in cerebellar Purkinje cells not only depends on synaptic plasticity but also on their intrinsic membrane excitability. We performed whole cell patch-clamp recordings of Purkinje cells in sagittal cerebellar slices in mice. We found that inducing long-term depression (LTD) in the parallel fiber to Purkinje cell synapses results in an increase in the gain of the firing rate response. This increase in excitability is accompanied by an increase in the input resistance and a decrease in the amplitude of the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel-mediated voltage sag. Application of a HCN channel blocker prevents the increase in input resistance and excitability without blocking the expression of synaptic LTD. We conclude that the induction of parallel fiber-Purkinje cell LTD is accompanied by an increase in excitability of Purkinje cells through downregulation of the HCN-mediated h current. We suggest that HCN downregulation is linked to the biochemical pathway that sustains synaptic LTD. Given the diversity of information carried by the parallel fiber system, we suggest that changes in intrinsic excitability enhance the coding capacity of the Purkinje cell to specific input sources.

  4. Altered dendritic development of cerebellar Purkinje cells in slice cultures from protein kinase C gamma-deficient mice

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    Schrenk, K; Kapfhammer, JP; Metzger, F


    Protein kinase C (PKC) is a key molecule for the expression of long-term depression at the parallel fiber-Purkinje cell synapse in the cerebellum, a well known model for synaptic plasticity, We have recently shown that activity of PKC also profoundly affects the dendritic morphology of Purkinje cell

  5. Axonal abnormalities in cerebellar Purkinje cells of the Ts65Dn mouse. (United States)

    Necchi, Daniela; Lomoio, Selene; Scherini, Elda


    Ts65Dn mice are a genetic model for Down syndrome. Among others, these mice have cerebellar pathology features which parallel those seen in Down syndrome patients. Both individuals with Down syndrome and Ts65Dn mice have reduced cerebellar volume and numbers of granule and Purkinje cells. In this report, we describe morphological abnormalities of axons of Purkinje cells in the cerebellum of Ts65Dn mice, by using anti-calbindin immunocytochemistry. A consistent number of Purkinje cells shows axons bearing giant varicosities along their transit through the granular layer. The cerebellar arbor vitae made by fasciculated Purkinje cell axons has a patchy appearance, some tracks being devoid of calbindin staining. The infraganglionic plexus, formed by recurrent collaterals of Purkinje cell axons, has enormously increased density, which is evidence for a compensatory reaction to degeneration of distal segments of axons. These alterations are accompanied by strong glial reaction as evidenced by GFAP immunocytochemistry. Moreover, the alterations are more consistent in the anterior lobules of the vermis and intermediate cortex. The axonal pathology of Purkinje cells may explain the impairment in cerebellar functions observed in Ts65Dn mice at the adulthood.

  6. Cerebellar endocannabinoids: retrograde signaling from purkinje cells. (United States)

    Marcaggi, Païkan


    The cerebellar cortex exhibits a strikingly high expression of type 1 cannabinoid receptor (CB1), the cannabinoid binding protein responsible for the psychoactive effects of marijuana. CB1 is primarily found in presynaptic elements in the molecular layer. While the functional importance of cerebellar CB1 is supported by the effect of gene deletion or exogenous cannabinoids on animal behavior, evidence for a role of endocannabinoids in synaptic signaling is provided by in vitro experiments on superfused acute rodent cerebellar slices. These studies have demonstrated that endocannabinoids can be transiently released by Purkinje cells and signal at synapses in a direction opposite to information transfer (retrograde). Here, following a description of the reported expression pattern of the endocannabinoid system in the cerebellum, I review the accumulated in vitro data, which have addressed the mechanism of retrograde endocannabinoid signaling and identified 2-arachidonoylglycerol as the mediator of this signaling. The mechanisms leading to endocannabinoid release, the effects of CB1 activation, and the associated synaptic plasticity mechanisms are discussed and the remaining unknowns are pointed. Notably, it is argued that the spatial specificity of this signaling and the physiological conditions required for its induction need to be determined in order to understand endocannabinoid function in the cerebellar cortex.

  7. Purkinje cell activity in the cerebellar anterior lobe after rabbit eyeblink conditioning (United States)

    Green, John T.; Steinmetz, Joseph E.


    The cerebellar anterior lobe may play a critical role in the execution and proper timing of learned responses. The current study was designed to monitor Purkinje cell activity in the rabbit cerebellar anterior lobe after eyeblink conditioning, and to assess whether Purkinje cells in recording locations may project to the interpositus nucleus. Rabbits were trained in an interstimulus interval discrimination procedure in which one tone signaled a 250-msec conditioned stimulus-unconditioned stimulus (CS-US) interval and a second tone signaled a 750-msec CS-US interval. All rabbits showed conditioned responses to each CS with mean onset and peak latencies that coincided with the CS-US interval. Many anterior lobe Purkinje cells showed significant learning-related activity after eyeblink conditioning to one or both of the CSs. More Purkinje cells responded with inhibition than with excitation to CS presentation. In addition, when the firing patterns of all conditioning-related Purkinje cells were pooled, it appeared that the population showed a pattern of excitation followed by inhibition during the CS-US interval. Using cholera toxin-conjugated horseradish peroxidase, Purkinje cells in recording areas were found to project to the interpositus nucleus. These data support previous studies that have suggested a role for the anterior cerebellar cortex in eyeblink conditioning as well as models of cerebellar-mediated CR timing that postulate that Purkinje cell activity inhibits conditioned response (CR) generation during the early portion of a trial by inhibiting the deep cerebellar nuclei and permits CR generation during the later portion of a trial through disinhibition of the cerebellar nuclei. PMID:15897252

  8. A signal processing analysis of Purkinje cells in vitro

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    Ze'ev R Abrams


    Full Text Available Cerebellar Purkinje cells in vitro fire recurrent sequences of Sodium and Calcium spikes. Here, we analyze the Purkinje cell using harmonic analysis, and our experiments reveal that its output signal is comprised of three distinct frequency bands, which are combined using Amplitude and Frequency Modulation (AM/FM. We find that the three characteristic frequencies - Sodium, Calcium and Switching – occur in various combinations in all waveforms observed using whole-cell current clamp recordings. We found that the Calcium frequency can display a frequency doubling of its frequency mode, and the Switching frequency can act as a possible generator of pauses that are typically seen in Purkinje output recordings. Using a reversibly photo-switchable kainate receptor agonist, we demonstrate the external modulation of the Calcium and Switching frequencies. These experiments and Fourier analysis suggest that the Purkinje cell can be understood as a harmonic signal oscillator, enabling a higher level of interpretation of Purkinje signaling based on modern signal processing techniques.

  9. A note on the definition and the development of cerebellar purkinje cell zones

    NARCIS (Netherlands)

    J. Voogd (Jan)


    textabstractThe definition of Purkinje cell zones by their white matter comprtments, their physiological properties, and their molecular identity and the birthdate of their Purkinje cells will be reviewed.

  10. Modulation, plasticity and pathophysiology of the parallel fiber-Purkinje cell synapse

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    Eriola Hoxha


    Full Text Available The parallel fiber-Purkinje cell synapse represents the point of maximal signal divergence in the cerebellar cortex with an estimated number of about 60 billion synaptic contacts in the rat and 100,000 billions in humans. At the same time, the Purkinje cell dendritic tree is a site of remarkable convergence of more than 100,000 parallel fiber synapses. Parallel fibers activity generates fast postsynaptic currents via AMPA receptors, and slower signals, mediated by mGlu1 receptors, resulting in Purkinje cell depolarization accompanied by sharp calcium elevation within dendritic regions. Long-term depression and long-term potentiation have been widely described for the parallel fiber-Purkinje cell synapse and have been proposed as mechanisms for motor learning. The mechanisms of induction for LTP and LTD involve different signaling mechanisms within the presynaptic terminal and/or at the postsynaptic site, promoting enduring modification in the neurotransmitter release and change in responsiveness to the neurotransmitter. The parallel fiber-Purkinje cell synapse is finely modulated by several neurotransmitters, including serotonin, noradrenaline, and acetylcholine. The ability of these neuromodulators to gate LTP and LTD at the parallel fiber-Purkinje cell synapse could, at least in part, explain their effect on cerebellar-dependent learning and memory paradigms. Overall, these findings have important implications for understanding the cerebellar involvement in a series of pathological conditions, ranging from ataxia to autism. For example, parallel fiber-Purkinje cell synapse dysfunctions have been identified in several murine models of spinocerebellar ataxia (SCA types 1, 3, 5 and 27. In some cases, the defect is specific for the AMPA receptor signaling (SCA27, while in others the mGlu1 pathway is affected (SCA1, 3, 5. Interestingly, the parallel fiber-Purkinje cell synapse has been shown to be hyper-functional in a mutant mouse model of autism

  11. Calcium, synaptic plasticity and intrinsic homeostasis in Purkinje neuron models

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    Pablo Achard


    Full Text Available We recently reproduced the complex electrical activity of a Purkinje cell (PC with very different combinations of ionic channel maximum conductances, suggesting that a large parameter space is available to homeostatic mechanisms. It has been hypothesized that cytoplasmic calcium concentrations control the homeostatic activity sensors. This raises many questions for PCs since in these neurons calcium plays an important role in the induction of synaptic plasticity. To address this question, we generated 148 new PC models. In these models the somatic membrane voltages are stable, but the somatic calcium dynamics are very variable, in agreement with experimental results. Conversely, the calcium signal in spiny dendrites shows only small variability. We demonstrate that this localized control of calcium conductances preserves the induction of long-term depression for all models. We conclude that calcium is unlikely to be the sole activity-sensor in this cell but that there is a strong relationship between activity homeostasis and synaptic plasticity.

  12. Encoding of whisker input by cerebellar Purkinje cells

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    L.W.J. Bosman (Laurens); S.K.E. Koekkoek (Bas); J. Shapiro (Joël); B.F.M. Rijken (Bianca); F. Zandstra (Froukje); B. van der Ende (Barry); C.B. Owens (Cullen); J.W. Potters (Jan Willem); J.R. de Gruijl (Jornt); T.J.H. Ruigrok (Tom); C.I. de Zeeuw (Chris)


    textabstractThe cerebellar cortex is crucial for sensorimotor integration. Sensorimotor inputs converge on cerebellar Purkinje cells via two afferent pathways: the climbing fibre pathway triggering complex spikes, and the mossy fibre-parallel fibre pathway, modulating the simple spike activities of

  13. Cerebellar Purkinje cells incorporate immunoglobulins and immunotoxins in vitro: implications for human neurological disease and immunotherapeutics

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    Rose John W


    Full Text Available Abstract Background Immunoglobulin G (IgG antibodies reactive with intracellular neuronal proteins have been described in paraneoplastic and other autoimmune disorders. Because neurons have been thought impermeable to immunoglobulins, however, such antibodies have been considered unable to enter neurons and bind to their specific antigens during life. Cerebellar Purkinje cells - an important target in paraneoplastic and other autoimmune diseases - have been shown in experimental animals to incorporate a number of molecules from cerebrospinal fluid. IgG has also been detected in Purkinje cells studied post mortem. Despite the possible significance of these findings for human disease, immunoglobulin uptake by Purkinje cells has not been demonstrated in living tissue or studied systematically. Methods To assess Purkinje cell uptake of immunoglobulins, organotypic cultures of rat cerebellum incubated with rat IgGs, human IgG, fluorescein-conjugated IgG, and rat IgM were studied by confocal microscopy in real time and following fixation. An IgG-daunorubicin immunotoxin was used to determine whether conjugation of pharmacological agents to IgG could be used to achieve Purkinje cell-specific drug delivery. Results IgG uptake was detected in Purkinje cell processes after 4 hours of incubation and in Purkinje cell cytoplasm and nuclei by 24-48 hours. Uptake could be followed in real time using IgG-fluorochrome conjugates. Purkinje cells also incorporated IgM. Intracellular immunoglobulin did not affect Purkinje cell viability, and Purkinje cells cleared intracellular IgG or IgM within 24-48 hours after transfer to media lacking immunoglobulins. The IgG-daunomycin immunotoxin was also rapidly incorporated into Purkinje cells and caused extensive, cell-specific death within 8 hours. Purkinje cell death was not produced by unconjugated daunorubicin or control IgG. Conclusion Purkinje cells in rat organotypic cultures incorporate and clear host (rat and non

  14. Transient developmental Purkinje cell axonal torpedoes in healthy and ataxic mouse cerebellum

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    Lovisa Ljungberg


    Full Text Available Information is carried out of the cerebellar cortical microcircuit via action potentials propagated along Purkinje cell axons. In several human neurodegenerative diseases, focal axonal swellings on Purkinje cells – known as torpedoes – have been associated with Purkinje cell loss. Interestingly, torpedoes are also reported to appear transiently during development in rat cerebellum. The function of Purkinje cell axonal torpedoes in health as well as in disease is poorly understood. We investigated the properties of developmental torpedoes in the postnatal mouse cerebellum of wildtype and transgenic mice. We found that Purkinje cell axonal torpedoes transiently appeared on axons of Purkinje neurons, with the largest number of torpedoes observed at postnatal day 11 (P11. This was after peak developmental apoptosis had occurred, when Purkinje cell counts in a lobule were static, suggesting that most developmental torpedoes appear on axons of neurons that persist into adulthood. We found that developmental torpedoes were not associated with a presynaptic GABAergic marker, indicating that they are not synapses. They were seldom found at axonal collateral branch points, and lacked microglia enrichment, suggesting that they are unlikely to be involved in axonal refinement. Interestingly, we found several differences between developmental torpedoes and disease-related torpedoes: developmental torpedoes occured largely on myelinated axons, and were not associated with changes in basket cell innervation on their parent soma. Disease-related torpedoes are typically reported to contain neurofilament; while the majority of developmental torpedoes did as well, a fraction of smaller developmental torpedoes did not. These differences indicate that developmental torpedoes may not be functionally identical to disease-related torpedoes. To study this further, we used a mouse model of spinocerebellar ataxia type 6 (SCA6, and found elevated disease

  15. Emergence of endoplasmic reticulum stress and activated microglia in Purkinje cell degeneration mice. (United States)

    Kyuhou, Shin-ichi; Kato, Nobuo; Gemba, Hisae


    In the current studies, we characterized the molecular and cellular mechanism of cell death in Purkinje cell degeneration (pcd) mice using real-time quantitative PCR, immunohistochemistry, and Western blotting. It appears that endoplasmic reticulum (ER) stress is involved in this degeneration of Purkinje cells because ER stress-related substrates, such as CHOP and caspase 12, were strongly activated in Purkinje cells of pcd mice during the third postnatal (P) week. A significant increase in the expression of the ER-specific chaperone BiP suggested that unfolded protein responses were induced. We also found that Purkinje cells underwent apoptosis via the activation of caspase 3 and subsequent fragmentation of DNA. In addition to the activation of apoptosis in Purkinje cells, many activated microglial cells are found to be present in the molecular layer of the cerebellar cortex. In the later phase of degeneration, there was conspicuous expression of inducible nitric oxide synthase (iNOS), and some Purkinje cells were strongly labeled with an antibody to nitrotyrosine, suggesting that Purkinje cells in pcd mice are damaged by nitric oxide released from microglial cells. Administration of minocycline, which may inhibit iNOS expression, delayed the death of Purkinje cells in pcd mice and mildly improved their motor abilities. These findings suggest that ER stress participates in the degeneration of Purkinje cells and that activation of microglia accelerates Purkinje cell death in pcd mice.

  16. Quantitative neuroanatomy of all Purkinje cells with light sheet microscopy and high-throughput image analysis

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    Ludovico eSilvestri


    Full Text Available Characterizing the cytoarchitecture of mammalian central nervous system on a brain-wide scale is becoming a compelling need in neuroscience. For example, realistic modeling of brain activity requires the definition of quantitative features of large neuronal populations in the whole brain. Quantitative anatomical maps will also be crucial to classify the cytoarchtitectonic abnormalities associated with neuronal pathologies in a high reproducible and reliable manner. In this paper, we apply recent advances in optical microscopy and image analysis to characterize the spatial distribution of Purkinje cells across the whole cerebellum. Light sheet microscopy was used to image with micron-scale resolution a fixed and cleared cerebellum of an L7-GFP transgenic mouse, in which all Purkinje cells are fluorescently labeled. A fast and scalable algorithm for fully automated cell identification was applied on the image to extract the position of all the fluorescent Purkinje cells. This vectorized representation of the cell population allows a thorough characterization of the complex three-dimensional distribution of the neurons, highlighting the presence of gaps inside the lamellar organization of Purkinje cells, whose density is believed to play a significant role in autism spectrum disorders. Furthermore, clustering analysis of the localized somata permits dividing the whole cerebellum in groups of Purkinje cells with high spatial correlation, suggesting new possibilities of anatomical partition. The quantitative approach presented here can be extended to study the distribution of different types of cell in many brain regions and across the whole encephalon, providing a robust base for building realistic computational models of the brain, and for unbiased morphological tissue screening in presence of pathologies and/or drug treatments.

  17. Vulnerability of Purkinje Cells Generated from Spinocerebellar Ataxia Type 6 Patient-Derived iPSCs

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    Yoshihito Ishida


    Full Text Available Spinocerebellar ataxia type 6 (SCA6 is a dominantly inherited neurodegenerative disease characterized by loss of Purkinje cells in the cerebellum. SCA6 is caused by CAG trinucleotide repeat expansion in CACNA1A, which encodes Cav2.1, α1A subunit of P/Q-type calcium channel. However, the pathogenic mechanism and effective therapeutic treatments are still unknown. Here, we have succeeded in generating differentiated Purkinje cells that carry patient genes by combining disease-specific iPSCs and self-organizing culture technologies. Patient-derived Purkinje cells exhibit increased levels of full-length Cav2.1 protein but decreased levels of its C-terminal fragment and downregulation of the transcriptional targets TAF1 and BTG1. We further demonstrate that SCA6 Purkinje cells exhibit thyroid hormone depletion-dependent degeneration, which can be suppressed by two compounds, thyroid releasing hormone and Riluzole. Thus, we have constructed an in vitro disease model recapitulating both ontogenesis and pathogenesis. This model may be useful for pathogenic investigation and drug screening.

  18. Time‐invariant feed‐forward inhibition of Purkinje cells in the cerebellar cortex in vivo (United States)

    Blot, Antonin; de Solages, Camille; Ostojic, Srdjan; Szapiro, German; Hakim, Vincent; Léna, Clément


    Key points We performed extracellular recording of pairs of interneuron–Purkinje cells in vivo.A single interneuron produces a substantial, short‐lasting, inhibition of Purkinje cells.Feed‐forward inhibition is associated with characteristic asymmetric cross‐correlograms. In vivo, Purkinje cell spikes only depend on the most recent synaptic activity. Abstract Cerebellar molecular layer interneurons are considered to control the firing rate and spike timing of Purkinje cells. However, interactions between these cell types are largely unexplored in vivo. Using tetrodes, we performed simultaneous extracellular recordings of neighbouring Purkinje cells and molecular layer interneurons, presumably basket cells, in adult rats in vivo. The high levels of afferent synaptic activity encountered in vivo yield irregular spiking and reveal discharge patterns characteristic of feed‐forward inhibition, thus suggesting an overlap of the afferent excitatory inputs between Purkinje cells and basket cells. Under conditions of intense background synaptic inputs, interneuron spikes exert a short‐lasting inhibitory effect, delaying the following Purkinje cell spike by an amount remarkably independent of the Purkinje cell firing cycle. This effect can be explained by the short memory time of the Purkinje cell potential as a result of the intense incoming synaptic activity. Finally, we found little evidence for any involvement of the interneurons that we recorded with the cerebellar high‐frequency oscillations promoting Purkinje cell synchrony. The rapid interactions between interneurons and Purkinje cells might be of particular importance in fine motor control because the inhibitory action of interneurons on Purkinje cells leads to deep cerebellar nuclear disinhibition and hence increased cerebellar output. PMID:26918702

  19. Atypical protein kinase C regulates primary dendrite specification of cerebellar Purkinje cells by localizing Golgi apparatus. (United States)

    Tanabe, Koji; Kani, Shuichi; Shimizu, Takashi; Bae, Young-Ki; Abe, Takaya; Hibi, Masahiko


    Neurons have highly polarized structures that determine what parts of the soma elaborate the axon and dendrites. However, little is known about the mechanisms that establish neuronal polarity in vivo. Cerebellar Purkinje cells extend a single primary dendrite from the soma that ramifies into a highly branched dendritic arbor. We used the zebrafish cerebellum to investigate the mechanisms by which Purkinje cells acquire these characteristics. To examine dendritic morphogenesis in individual Purkinje cells, we marked the cell membrane using a Purkinje cell-specific promoter to drive membrane-targeted fluorescent proteins. We found that zebrafish Purkinje cells initially extend multiple neurites from the soma and subsequently retract all but one, which becomes the primary dendrite. In addition, the Golgi apparatus specifically locates to the root of the primary dendrite, and its localization is already established in immature Purkinje cells that have multiple neurites. Inhibiting secretory trafficking through the Golgi apparatus reduces dendritic growth, suggesting that the Golgi apparatus is involved in the dendritic morphogenesis. We also demonstrated that in a mutant of an atypical protein kinase C (aPKC), Prkci, Purkinje cells retain multiple primary dendrites and show disrupted localization of the Golgi apparatus. Furthermore, a mosaic inhibition of Prkci in Purkinje cells recapitulates the aPKC mutant phenotype. These results suggest that the aPKC cell autonomously controls the Golgi localization and thereby regulates the specification of the primary dendrite of Purkinje cells.

  20. Voltage-gated sodium channels in cerebellar Purkinje cells of mormyrid fish

    NARCIS (Netherlands)

    M.M. de Ruiter (Martijn); C.I. de Zeeuw (Chris); C.R.W. Hansel (Christian)


    textabstractCerebellar Purkinje cells of mormyrid fish differ in some morphological as well as physiological parameters from their counterparts in mammals. Morphologically, Purkinje cells of mormyrids have larger dendrites that are characterized by a lower degree of branching in the molecular layer.

  1. Calcium Imaging Reveals Coordinated Simple Spike Pauses in Populations of Cerebellar Purkinje Cells

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    Jorge E. Ramirez


    Full Text Available The brain’s control of movement is thought to involve coordinated activity between cerebellar Purkinje cells. The results reported here demonstrate that somatic Ca2+ imaging is a faithful reporter of Na+-dependent “simple spike” pauses and enables us to optically record changes in firing rates in populations of Purkinje cells in brain slices and in vivo. This simultaneous calcium imaging of populations of Purkinje cells reveals a striking spatial organization of pauses in Purkinje cell activity between neighboring cells. The source of this organization is shown to be the presynaptic gamma-Aminobutyric acid producing (GABAergic network, and blocking ionotropic gamma-Aminobutyric acid receptor (GABAARs abolishes the synchrony. These data suggest that presynaptic interneurons synchronize (inactivity between neighboring Purkinje cells, and thereby maximize their effect on downstream targets in the deep cerebellar nuclei.

  2. Fear conditioning-related changes in cerebellar Purkinje cell activities in goldfish

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    Yoshida Masayuki


    Full Text Available Abstract Background Fear conditioning-induced changes in cerebellar Purkinje cell responses to a conditioned stimulus have been reported in rabbits. It has been suggested that synaptic long-term potentiation and the resulting increases in firing rates of Purkinje cells are related to the acquisition of conditioned fear in mammals. However, Purkinje cell activities during acquisition of conditioned fear have not been analysed, and changes in Purkinje cell activities throughout the development of conditioned fear have not yet been investigated. In the present study, we tracked Purkinje cell activities throughout a fear conditioning procedure and aimed to elucidate further how cerebellar circuits function during the acquisition and expression of conditioned fear. Methods Activities of single Purkinje cells in the corpus cerebelli were tracked throughout a classical fear conditioning procedure in goldfish. A delayed conditioning paradigm was used with cardiac deceleration as the conditioned response. Conditioning-related changes of Purkinje cell responses to a conditioned stimulus and unconditioned stimulus were examined. Results The majority of Purkinje cells sampled responded to the conditioned stimulus by either increasing or decreasing their firing rates before training. Although there were various types of conditioning-related changes in Purkinje cells, more than half of the cells showed suppressed activities in response to the conditioned stimulus after acquisition of conditioned fear. Purkinje cells that showed unconditioned stimulus-coupled complex-spike firings also exhibited conditioning-related suppression of simple-spike responses to the conditioned stimulus. A small number of Purkinje cells showed increased excitatory responses in the acquisition sessions. We found that the magnitudes of changes in the firing frequencies of some Purkinje cells in response to the conditioned stimulus correlated with the magnitudes of the conditioned

  3. Determinants of action potential propagation in cerebellar Purkinje cell axons. (United States)

    Monsivais, Pablo; Clark, Beverley A; Roth, Arnd; Häusser, Michael


    Axons have traditionally been viewed as highly faithful transmitters of action potentials. Recently, however, experimental evidence has accumulated to support the idea that under some circumstances axonal propagation may fail. Cerebellar Purkinje neurons fire highfrequency simple spikes, as well as bursts of spikes in response to climbing fiber activation (the "complex spike"). Here we have visualized the axon of individual Purkinje cells to directly investigate the relationship between somatic spikes and axonal spikes using simultaneous somatic whole-cell and cell-attached axonal patch-clamp recordings at 200-800 microm from the soma. We demonstrate that sodium action potentials propagate at frequencies up to approximately 260 Hz, higher than simple spike rates normally observed in vivo. Complex spikes, however, did not propagate reliably, with usually only the first and last spikes in the complex spike waveform being propagated. On average, only 1.7 +/- 0.2 spikes in the complex spike were propagated during resting firing, with propagation limited to interspike intervals above approximately 4 msec. Hyperpolarization improved propagation efficacy without affecting total axonal spike number, whereas strong depolarization could abolish propagation of the complex spike. These findings indicate that the complex spike waveform is not faithfully transmitted to downstream synapses and that propagation of the climbing fiber response may be modulated by background activity.

  4. Ataxia and Purkinje cell degeneration in mice lacking the CAMTA1 transcription factor (United States)

    Long, Chengzu; Grueter, Chad E.; Song, Kunhua; Qin, Song; Qi, Xiaoxia; Kong, Y. Megan; Shelton, John M.; Richardson, James A.; Zhang, Chun-Li; Bassel-Duby, Rhonda; Olson, Eric N.


    Members of the calmodulin-binding transcription activator (CAMTA) family of proteins function as calcium-sensitive regulators of gene expression in multicellular organisms ranging from plants to humans. Here, we show that global or nervous system deletion of CAMTA1 in mice causes severe ataxia with Purkinje cell degeneration and cerebellar atrophy, partially resembling the consequences of haploinsufficiency of the human CAMTA1 locus. Gene-expression analysis identified a large collection of neuronal genes that were dysregulated in the brains of CAMTA1-mutant mice, and elucidation of a consensus sequence for binding of CAMTA proteins to DNA revealed the association of CAMTA-binding sites with many of these genes. We conclude that CAMTA1 plays an essential role in the control of Purkinje cell function and survival. CAMTA1-mutant mice provide a model to study the molecular mechanisms of neurodegenerative diseases and for screening potential therapeutic interventions for such disorders. PMID:25049392

  5. Temporal effects of thyroid hormone (TH) and decabrominated diphenyl ether (BDE209) on Purkinje cell dendrite arborization. (United States)

    Ibhazehiebo, K; Koibuchi, N


    Thyroid hormones (TH) 3,3',4-tri-iodothyronine (T3) and 3,3',4,4'-tetra-iodothyronine (T4) plays crucial role in cerebellar development. Deficiency of TH consistently results in aberrant growth and development of the cerebellum including reduced growth and branching of the Purkinje cells. In rodents, the critical period of thyroid hormone action on cerebellum development is within the first two to three weeks, after which thyroid hormone replacement cannot fully reverse abnormal cerebellar development induced by thyroid hormone insult. Decabrominated diphenyl ether (BDE209) is an industrial reagent used as an additive flame retardant to reduce flammability of various commercial and household produce. BDE209 has bio-accumulative potential and is neurotoxic. Previously, we have shown that T4 (10-8 M) induced extensive dendrite arborization of Purkinje cells and low dose BDE209 (10-10 M) remarkably suppressed TH-induced Purkinje cell dendrite arborization. In the present study, we show that the critical period for TH-induced Purkinje cell growth and dendrite arborization in culture is much earlier than reported in animal models. Also, we show for the first time that low dose BDE209 suppressed TH-induced dendrite arborization in a time-dependent manner. Taken together, our study indicates that hypothyroidism and exposure to BDE209 during critical stage of cerebellar development can lead to impaired Purkinje cell growth and dendrite arborization and may consequently disrupt normal cerebellar functions.

  6. Regional Regulation of Purkinje Cell Dendritic Spines by Integrins and Eph/Ephrins. (United States)

    Heintz, Tristan G; Eva, Richard; Fawcett, James W


    Climbing fibres and parallel fibres compete for dendritic space on Purkinje cells in the cerebellum. Normally, climbing fibres populate the proximal dendrites, where they suppress the multiple small spines typical of parallel fibres, leading to their replacement by the few large spines that contact climbing fibres. Previous work has shown that ephrins acting via EphA4 are a signal for this change in spine type and density. We have used an in vitro culture model in which to investigate the ephrin effect on Purkinje cell dendritic spines and the role of integrins in these changes. We found that integrins α3, α5 and β4 are present in many of the dendritic spines of cultured Purkinje cells. pFAK, the main downstream signalling molecule from integrins, has a similar distribution, although the intenstity of pFAK staining and the percentage of pFAK+ spines was consistently higher in the proximal dendrites. Activating integrins with Mg2+ led to an increase in the intensity of pFAK staining and an increase in the proportion of pFAK+ spines in both the proximal and distal dendrites, but no change in spine length, density or morphology. Blocking integrin binding with an RGD-containing peptide led to a reduction in spine length, with more stubby spines on both proximal and distal dendrites. Treatment of the cultures with ephrinA3-Fc chimera suppressed dendritic spines specifically on the proximal dendrites and there was also a decrease of pFAK in spines on this domain. This effect was blocked by simultaneous activation of integrins with Mn2+. We conclude that Eph/ephrin signaling regulates proximal dendritic spines in Purkinje cells by inactivating integrin downstream signalling.

  7. The autosomal dominant spinocerebellar ataxias: emerging mechanistic themes suggest pervasive Purkinje cell vulnerability. (United States)

    Hekman, Katherine E; Gomez, Christopher M


    The spinocerebellar ataxias are a genetically heterogeneous group of disorders with clinically overlapping phenotypes arising from Purkinje cell degeneration, cerebellar atrophy and varying degrees of degeneration of other grey matter regions. For 22 of the 32 subtypes, a genetic cause has been identified. While recurring themes are emerging, there is no clear correlation between the clinical phenotype or penetrance, the type of genetic defect or the category of the disease mechanism, or the neuronal types involved beyond Purkinje cells. These phenomena suggest that cerebellar Purkinje cells may be a uniquely vulnerable neuronal cell type, more susceptible to a wider variety of genetic/cellular insults than most other neuron types.

  8. Purkinje cell heterotopy with cerebellar hypoplasia in two free-living American kestrels (Falco sparverius). (United States)

    Armién, A G; McRuer, D L; Ruder, M G; Wünschmann, A


    Two wild fledgling kestrels exhibited lack of motor coordination, postural reaction deficits, and abnormal propioception. At necropsy, the cerebellum and brainstem were markedly underdeveloped. Microscopically, there was Purkinje cells heterotopy, abnormal circuitry, and hypoplasia with defective foliation. Heterotopic neurons were identified as immature Purkinje cells by their size, location, immunoreactivity for calbindin D-28 K, and ultrastructural features. The authors suggest that this cerebellar abnormality was likely due to a disruption of molecular mechanisms that dictate Purkinje cell migration, placement, and maturation in early embryonic development. The etiology of this condition remains undetermined. Congenital central nervous system disorders have rarely been reported in birds.

  9. Modeling tissue- and mutation- specific electrophysiological effects in the long QT syndrome: role of the Purkinje fiber.

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    Vivek Iyer

    Full Text Available Congenital long QT syndrome is a heritable family of arrhythmias caused by mutations in 13 genes encoding ion channel complex proteins. Mounting evidence has implicated the Purkinje fiber network in the genesis of ventricular arrhythmias. In this study, we explore the hypothesis that long QT mutations can demonstrate different phenotypes depending on the tissue type of expression. Using computational models of the human ventricular myocyte and the Purkinje fiber cell, the biophysical alteration in channel function in LQT1, LQT2, LQT3, and LQT7 are modeled. We identified that the plateau potential was important in LQT1 and LQT2, in which mutation led to minimal action potential prolongation in Purkinje fiber cells. The phenotype of LQT3 mutation was dependent on the biophysical alteration induced as well as tissue type. The canonical ΔKPQ mutation causes severe action potential prolongation in both tissue types. For LQT3 mutation F1473C, characterized by shifted channel availability, a more severe phenotype was seen in Purkinje fiber cells with action potential prolongation and early afterdepolarizations. The LQT3 mutation S1904L demonstrated striking effects on action potential duration restitution and more severe action potential prolongation in Purkinje fiber cells at higher heart rates. Voltage clamp simulations highlight the mechanism of effect of these mutations in different tissue types, and impact of drug therapy is explored. We conclude that arrhythmia formation in long QT syndrome may depend not only on the basis of mutation and biophysical alteration, but also upon tissue of expression. The Purkinje fiber network may represent an important therapeutic target in the management of patients with heritable channelopathies.

  10. Purkinje cell heterotopy with cerebellar hypoplasia in two free-living American kestrels (Falco sparverius) (United States)

    Two wild fledgling kestrels exhibited lack of motor coordination, postural reaction deficits, and abnormal propioception. At necropsy, the cerebellum and brainstem were markedly underdeveloped. Microscopically, there was Purkinje cells heterotopy, abnormal circuitry, and hypoplasia with defective fo...

  11. Cbln1 downregulates the formation and function of inhibitory synapses in mouse cerebellar Purkinje cells. (United States)

    Ito-Ishida, Aya; Kakegawa, Wataru; Kohda, Kazuhisa; Miura, Eriko; Okabe, Shigeo; Yuzaki, Michisuke


    The formation of excitatory and inhibitory synapses must be tightly coordinated to establish functional neuronal circuitry during development. In the cerebellum, the formation of excitatory synapses between parallel fibers and Purkinje cells is strongly induced by Cbln1, which is released from parallel fibers and binds to the postsynaptic δ2 glutamate receptor (GluD2). However, Cbln1's role, if any, in inhibitory synapse formation has been unknown. Here, we show that Cbln1 downregulates the formation and function of inhibitory synapses between Purkinje cells and interneurons. Immunohistochemical analyses with an anti-vesicular GABA transporter antibody revealed an increased density of interneuron-Purkinje cell synapses in the cbln1-null cerebellum. Whole-cell patch-clamp recordings from Purkinje cells showed that both the amplitude and frequency of miniature inhibitory postsynaptic currents were increased in cbln1-null cerebellar slices. A 3-h incubation with recombinant Cbln1 reversed the increased amplitude of inhibitory currents in Purkinje cells in acutely prepared cbln1-null slices. Furthermore, an 8-day incubation with recombinant Cbln1 reversed the increased interneuron-Purkinje cell synapse density in cultured cbln1-null slices. In contrast, recombinant Cbln1 did not affect cerebellar slices from mice lacking both Cbln1 and GluD2. Finally, we found that tyrosine phosphorylation was upregulated in the cbln1-null cerebellum, and acute inhibition of Src-family kinases suppressed the increased inhibitory postsynaptic currents in cbln1-null Purkinje cells. These findings indicate that Cbln1-GluD2 signaling inhibits the number and function of inhibitory synapses, and shifts the excitatory-inhibitory balance towards excitation in Purkinje cells. Cbln1's effect on inhibitory synaptic transmission is probably mediated by a tyrosine kinase pathway.

  12. Purkinje cell-specific ablation of Cav2.1 channels is sufficient to cause cerebellar ataxia in mice. (United States)

    Todorov, Boyan; Kros, Lieke; Shyti, Reinald; Plak, Petra; Haasdijk, Elize D; Raike, Robert S; Frants, Rune R; Hess, Ellen J; Hoebeek, Freek E; De Zeeuw, Chris I; van den Maagdenberg, Arn M J M


    The Cacna1a gene encodes the α(1A) subunit of voltage-gated Ca(V)2.1 Ca(2+) channels that are involved in neurotransmission at central synapses. Ca(V)2.1-α(1)-knockout (α1KO) mice, which lack Ca(V)2.1 channels in all neurons, have a very severe phenotype of cerebellar ataxia and dystonia, and usually die around postnatal day 20. This early lethality, combined with the wide expression of Ca(V)2.1 channels throughout the cerebellar cortex and nuclei, prohibited determination of the contribution of particular cerebellar cell types to the development of the severe neurobiological phenotype in Cacna1a mutant mice. Here, we crossed conditional Cacna1a mice with transgenic mice expressing Cre recombinase, driven by the Purkinje cell-specific Pcp2 promoter, to specifically ablate the Ca(V)2.1-α(1A) subunit and thereby Ca(V)2.1 channels in Purkinje cells. Purkinje cell Ca(V)2.1-α(1A)-knockout (PCα1KO) mice aged without difficulties, rescuing the lethal phenotype seen in α1KO mice. PCα1KO mice exhibited cerebellar ataxia starting around P12, much earlier than the first signs of progressive Purkinje cell loss, which appears in these mice between P30 and P45. Secondary cell loss was observed in the granular and molecular layers of the cerebellum and the volume of all individual cerebellar nuclei was reduced. In this mouse model with a cell type-specific ablation of Ca(V)2.1 channels, we show that ablation of Ca(V)2.1 channels restricted to Purkinje cells is sufficient to cause cerebellar ataxia. We demonstrate that spatial ablation of Ca(V)2.1 channels may help in unraveling mechanisms of human disease.

  13. The volume of Purkinje cells decreases in the cerebellum of acrylamide-intoxicated rats, but no cells are lost

    DEFF Research Database (Denmark)

    Larsen, Jytte Overgaard; Tandrup, T; Braendgaard, H


    The effects of acrylamide intoxication on the numbers of granule and Purkinje cells and the volume of Purkinje cell perikarya have been evaluated with stereological methods. The analysis was carried out in the cerebella of rats that had received a dose of 33.3 mg/kg acrylamide, twice a week, for 7...

  14. Morphometry of purkinje cell body of cerebellum in bangladeshi cadaver. (United States)

    Haque, M A; Khalil, M; Khalil, M; Sultana, S Z; Mannan, S; Rahman, M; Ara, A; Begum, T; Choudhury, S; Haque, N


    This cross sectional descriptive study was performed by examining 30 (thirty) relatively fresh cerebellum. Out of them 20 postmortem human cerebellum collected from Bangladeshi cadavers of both sexes (male 10 and female 10) age ranging from 5 to 60 years and 10 cerebellums from caesarian section of dead fetuses of both sexes (male 6 and female 4) age ranging from 34 weeks to 41 weeks. Specimen containing cerebellum was collected from dead bodies autopsied on different dates from April'2009 to September'2009 at the autopsy laboratory of department of Forensic Medicine and Gynaecology and Obstetrics of Mymensingh Medical College, Mymensingh. Samples were collected by using nonprobability sampling technique. The collected sample was grouped in to three age groups like Group A (34 to 41 weeks of gestation), Group B (5 to 30 years) and Group C (31 to 60 years) and two sex groups (male and female). Ten cerebellums were studied from each age group for this histological study. Sections were processed following standard histological procedure and were stained with Hematoxylin and Eosin stain. Slides were examined under 15X40 magnifications and measurement of vertical and transverse diameter of the cell body were taken with the help of ocular micrometer. In this study, the mean difference of mean vertical and transverse diameter of Purkinje cell body between Groups A & B and Groups A & C was statistically highly significant (p<0.001) but differences between Groups B & C was statistically significant only in case of transverse diameter.

  15. An improved method for culturing cerebellar Purkinje cells with differentiated dendrites under a mixed monolayer setting. (United States)

    Furuya, S; Makino, A; Hirabayashi, Y


    We report here a novel cell culture protocol which facilitates in vitro survival and dendritic differentiation of cerebellar Purkinje cells in a monolayer, mixed culture setting. We found that the type of culture medium is a critical factor for the maintenance of these cells. Purkinje cells present in the single cell suspension of embryonic rat cerebellum were best maintained in a medium based on Dulbecco's modified Eagle's medium (DMEM)/F-12 without the addition of known neurotrophic factors. These cells maintained in DMEM/F-12-based media displayed an approximately 2.5-3.5-fold increase in survival compared with cells maintained in the widely used Basal Medium Eagle's (BME)-based serum-free culture medium with the same supplements. This novel protocol permits not only enhanced survival but also accelerated, improved dendritic differentiation of these cells. Purkinje cells developed highly branched spiny dendrites by 14-16 days in vitro, which matches the time course of the dendritic growth of these cells in vivo. The Purkinje cells expressed metabotropic glutamate receptor 1alpha in the cell bodies and branched dendrites, and the intradendritic calcium concentration increased when trans-ACPD, a selective agonist of this receptor, was applied. This novel protocol allows the development of functional branched dendrites and therefore is useful for electrophysiological and ion-imaging studies on dendrites of Purkinje cells grown in vitro.

  16. Prenatal infection decreases calbindin, decreases Purkinje cell volume and density and produces long-term motor deficits in Sprague-Dawley rats. (United States)

    Wallace, K; Veerisetty, S; Paul, I; May, W; Miguel-Hidalgo, J J; Bennett, W


    The cerebellum is involved in the control of motor functions with Purkinje cells serving as the only output from the cerebellum. Purkinje cells are important targets for toxic substances and are vulnerable to prenatal insults. Intrauterine infection (IUI) has been shown to selectively target the developing cerebral white matter through lesioning, necrosis and inflammatory cytokine activation. Developmental and cognitive delays have been associated with animal models of IUI. The aim of this study was to determine if IUI leads to damage to Purkinje cells in the developing cerebellum and if any damage is associated with decreases in calbindin and motor behaviors in surviving pups. Pregnant rats were injected with Escherichia coli (1 × 10⁵ colony-forming units) or sterile saline at gestational day 17. Beginning at postnatal day (PND) 2, the pups were subjected to a series of developmental tests to examine developmental milestones. At PND 16, some pups were sacrificed and their brains extracted and processed for histology or protein studies. Hematoxylin and eosin (HE) staining was done to examine the general morphology of the Purkinje cells and to examine Purkinje cell density, area and volume. Calbindin expression was examined in the cerebellum via immunohistochemistry and Western blot techniques. The remaining rat pups were used to examine motor coordination and balance on a rotating rotarod at the prepubertal and adult ages. Prenatal E. coli injection did not significantly change birth weight or delivery time, but did delay surface righting and negative geotaxis in pups. Pups in the E. coli group also had a decrease in the number of Purkinje cells, as well as a decrease in Purkinje cell density and volume. HE staining demonstrated a change in Purkinje cell morphology. Calbindin expression was decreased in rats from the E. coli group as well. Locomotor tests indicated that while there were no significant changes in gross motor activity, motor coordination and

  17. Molecular mechanisms governing competitive synaptic wiring in cerebellar Purkinje cells. (United States)

    Watanabe, Masahiko


    Cerebellar Purkinje cells (PCs) play a principal role in motor coordination and motor learning. To fulfill these functions, PCs receive and integrate two types of excitatory inputs, climbing fiber (CF) and parallel fiber (PF). CFs are projection axons from the inferior olive, and convey error signals to PCs. On the other hand, PFs are T-shaped axons of cerebellar granule cells, and convey sensory and motor information carried through the pontocerebellar and spinocerebellar mossy fiber pathways. The most remarkable feature of PC circuits is the highly territorial innervation by these two excitatory afferents. A single climbing CF powerfully and exclusively innervates proximal PC dendrites, whereas hundreds of thousands of PFs innervate distal PC dendrites. Recent studies using gene-manipulated mice have been elucidating that the PC circuitry is formed and maintained by molecular mechanisms that fuel homosynaptic competition among CFs and heterosynaptic competition between CFs and PFs. GluRdelta2 (a PC-specific glutamate receptor) and precerebellin or Cbln1 (a granule cell-derived secretory protein) cooperatively work for selective strengthening of PF-PC synapses, and prevent excessive distal extension of CFs that eventually causes multiple innervation at distal dendrites. In contrast, P/Q-type Ca2+ channels, which mediate Ca2+ influx upon CF activity, selectively strengthen the innervation by a single main CF, and expel PFs and other CFs from proximal dendrites that it innervates. Therefore, we now understand that owing to these mechanisms, territorial innervation by CFs and PFs is properly structured and mono-innervation by CFs is established. Several key issues for future study are also discussed.

  18. Regulation and functional roles of rebound potentiation at cerebellar stellate cell - Purkinje cell synapses

    Directory of Open Access Journals (Sweden)

    Tomoo eHirano


    Full Text Available Purkinje cells receive both excitatory and inhibitory synaptic inputs and send sole output from the cerebellar cortex. Long-term depression, a type of synaptic plasticity, at excitatory parallel fiber–Purkinje cell synapses has been studied extensively as a primary cellular mechanism of motor learning. On the other hand, at inhibitory synapses on a Purkinje cell, postsynaptic depolarization induces long-lasting potentiation of GABAergic synaptic transmission. This synaptic plasticity is called rebound potentiation (RP, and its molecular regulatory mechanisms have been studied. The increase in intracellular Ca2+ concentration caused by depolarization induces RP through enhancement of GABAA receptor (GABAAR responsiveness. RP induction depends on binding of GABAAR with GABAAR associated protein (GABARAP which is regulated by Ca2+/calmodulin-dependent kinase II (CaMKII. Whether RP is induced or not is determined by the balance between phosphorylation and de-phosphorylation activities regulated by intracellular Ca2+ and by metabotropic GABA and glutamate receptors. Recent studies have revealed that the subunit composition of CaMKII has significant impact on RP induction. A Purkinje cell expresses both alpha- and beta-CaMKII, and the latter has much higher affinity for Ca2+/calmodulin than the former. It was shown that when the relative amount of alpha- to beta-CaMKII is large, RP induction is suppressed. The functional significance of RP has also been studied using transgenic mice in which a peptide inhibiting association of GABARAP and GABAAR is expressed selectively in Purkinje cells. The transgenic mice show abrogation of RP and subnormal adaptation of vestibulo-ocular reflex, a type of motor learning. Thus, RP is involved in a certain type of motor learning.

  19. Alteration in 5-hydroxymethylcytosine-mediated epigenetic regulation leads to Purkinje cell vulnerability in ATM deficiency. (United States)

    Jiang, Dewei; Zhang, Ying; Hart, Ronald P; Chen, Jianmin; Herrup, Karl; Li, Jiali


    A long-standing mystery surrounding ataxia-telangiectasia is why it is mainly cerebellar neurons, Purkinje cells in particular, that appear vulnerable to ATM deficiency. Here we present data showing that 5-hydroxymethylcytosine (5hmC), a newly recognized epigenetic marker found at high levels in neurons, is substantially reduced in human ataxia-telangiectasia and Atm(-/-) mouse cerebellar Purkinje cells. We further show that TET1, an enzyme that converts 5-methylcytosine (5mC) to 5hmC, responds to DNA damage and manipulation of TET1 activity directly affects the DNA damage signalling and ATM-deficient neuronal cell cycle re-entry and death. Quantitative genome-wide analysis of 5hmC-containing sequences shows that in ATM deficiency there is a cerebellum- and Purkinje cell-specific shift in 5hmC enrichment in both regulatory elements and repeated sequences. Finally, we verify that TET1-mediated 5hmC production is linked to the degenerative process of Purkinje cells and behavioural deficits in Atm(-/-) mice. Taken together, the selective loss of 5hmC plays a critical role in driving Purkinje cell vulnerability in ATM deficiency.

  20. Toluene decreases Purkinje cell output by enhancing inhibitory synaptic transmission in the cerebellar cortex. (United States)

    Gmaz, Jimmie M; McKay, Bruce E


    Toluene belongs to a class of psychoactive drugs known as inhalants. Found in common household products such as adhesives, paint products, and aerosols, toluene is inhaled for its intoxicating and euphoric properties. Additionally, exposure to toluene disrupts motor behaviors in a manner consistent with impairments to cerebellar function. Previous work has suggested a role of GABA in mediating toluene's neurobehavioral effects, but how this manifests in the cerebellar cortex is not yet understood. In the present study, we examined the effects of toluene on cerebellar Purkinje cell action potential output and inhibitory synaptic transmission onto Purkinje cells using patch clamp electrophysiology in acute rat cerebellar slices. Toluene (1mM) reduced the frequency of Purkinje cell action potential output without affecting input resistance. Furthermore, toluene dose-dependently enhanced inhibitory synaptic transmission onto Purkinje cells, increasing the amplitude and frequency of inhibitory postsynaptic currents; no change in the frequency of action potentials from molecular layer interneurons was noted. The observed decreases in Purkinje cell action potential output could contribute to toluene-evoked impairments in cerebellar and motor functions. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  1. Systematic regional variations in Purkinje cell spiking patterns.

    Directory of Open Access Journals (Sweden)

    Jianqiang Xiao

    Full Text Available In contrast to the uniform anatomy of the cerebellar cortex, molecular and physiological studies indicate that significant differences exist between cortical regions, suggesting that the spiking activity of Purkinje cells (PCs in different regions could also show distinct characteristics. To investigate this possibility we obtained extracellular recordings from PCs in different zebrin bands in crus IIa and vermis lobules VIII and IX in anesthetized rats in order to compare PC firing characteristics between zebrin positive (Z+ and negative (Z- bands. In addition, we analyzed recordings from PCs in the A2 and C1 zones of several lobules in the posterior lobe, which largely contain Z+ and Z- PCs, respectively. In both datasets significant differences in simple spike (SS activity were observed between cortical regions. Specifically, Z- and C1 PCs had higher SS firing rates than Z+ and A2 PCs, respectively. The irregularity of SS firing (as assessed by measures of interspike interval distribution was greater in Z+ bands in both absolute and relative terms. The results regarding systematic variations in complex spike (CS activity were less consistent, suggesting that while real differences can exist, they may be sensitive to other factors than the cortical location of the PC. However, differences in the interactions between SSs and CSs, including the post-CS pause in SSs and post-pause modulation of SSs, were also consistently observed between bands. Similar, though less strong trends were observed in the zonal recordings. These systematic variations in spontaneous firing characteristics of PCs between zebrin bands in vivo, raises the possibility that fundamental differences in information encoding exist between cerebellar cortical regions.

  2. Molecular mechanism of parallel fiber-Purkinje cell synapse formation. (United States)

    Mishina, Masayoshi; Uemura, Takeshi; Yasumura, Misato; Yoshida, Tomoyuki


    The cerebellum receives two excitatory afferents, the climbing fiber (CF) and the mossy fiber-parallel fiber (PF) pathway, both converging onto Purkinje cells (PCs) that are the sole neurons sending outputs from the cerebellar cortex. Glutamate receptor δ2 (GluRδ2) is expressed selectively in cerebellar PCs and localized exclusively at the PF-PC synapses. We found that a significant number of PC spines lack synaptic contacts with PF terminals and some of residual PF-PC synapses show mismatching between pre- and postsynaptic specializations in conventional and conditional GluRδ2 knockout mice. Studies with mutant mice revealed that in addition to PF-PC synapse formation, GluRδ2 is essential for synaptic plasticity, motor learning, and the restriction of CF territory. GluRδ2 regulates synapse formation through the amino-terminal domain, while the control of synaptic plasticity, motor learning, and CF territory is mediated through the carboxyl-terminal domain. Thus, GluRδ2 is the molecule that bridges synapse formation and motor learning. We found that the trans-synaptic interaction of postsynaptic GluRδ2 and presynaptic neurexins (NRXNs) through cerebellin 1 (Cbln1) mediates PF-PC synapse formation. The synaptogenic triad is composed of one molecule of tetrameric GluRδ2, two molecules of hexameric Cbln1 and four molecules of monomeric NRXN. Thus, GluRδ2 triggers synapse formation by clustering four NRXNs. These findings provide a molecular insight into the mechanism of synapse formation in the brain.

  3. Molecular mechanism of parallel fiber-Purkinje cell synapse formation

    Directory of Open Access Journals (Sweden)

    Masayoshi eMishina


    Full Text Available The cerebellum receives two excitatory afferents, the climbing fiber (CF and the mossy fiber-parallel fiber (PF pathway, both converging onto Purkinje cells (PCs that are the sole neurons sending outputs from the cerebellar cortex. Glutamate receptor δ2 (GluRδ2 is expressed selectively in cerebellar PCs and localized exclusively at the PF-PC synapses. We found that a significant number of PC spines lack synaptic contacts with PF terminals and some of residual PF-PC synapses show mismatching between pre- and postsynaptic specializations in conventional and conditional GluRδ2 knockout mice. Studies with mutant mice revealed that in addition to PF-PC synapse formation, GluRδ2 is essential for synaptic plasticity, motor learning and the restriction of CF territory. GluRδ2 regulates synapse formation through the amino-terminal domain, while the control of synaptic plasticity, motor learning and CF territory is mediated through the carboxyl-terminal domain. Thus, GluRδ2 is the molecule that bridges synapse formation and motor learning. We found that the trans-synaptic interaction of postsynaptic GluRδ2 and presynaptic neurexins (NRXNs through Cbln1 mediates PF-PC synapse formation. The synaptogenic triad is composed of one molecule of tetrameric GluRδ2, two molecules of hexameric Cbln1 and four molecules of monomeric NRXN. Thus, GluRδ2 triggers synapse formation by clustering four NRXNs. These findings provide a molecular insight into the mechanism of synapse formation in the brain.

  4. Climbing fiber synapse elimination in cerebellar Purkinje cells. (United States)

    Watanabe, Masahiko; Kano, Masanobu


    Innervation of Purkinje cells (PCs) by multiple climbing fibers (CFs) is refined into mono-innervation during the first three postnatal weeks of rodents' lives. In this review article, we will integrate the current knowledge on developmental process and mechanisms of CF synapse elimination. In the 'creeper' stage of CF innervation (postnatal day 0 (P0)∼), CFs creep among PC somata to form transient synapses on immature dendrites. In the 'pericellular nest' stage (P5∼), CFs densely surround and innervate PC somata. CF innervation is then displaced to the apical portion of PC somata in the 'capuchon' stage (P9∼), and translocate to dendrites in the 'dendritic' (P12∼) stage. Along with the developmental changes in CF wiring, functional and morphological distinctions become larger among CF inputs. PCs are initially innervated by more than five CFs with similar strengths (∼P3). During P3-7 only a single CF is selectively strengthened (functional differentiation), and it undergoes dendritic translocation from P9 on (dendritic translocation). Following the functional differentiation, perisomatic CF synapses are eliminated nonselectively; this proceeds in two distinct phases. The early phase (P7-11) is conducted independently of parallel fiber (PF)-PC synapse formation, while the late phase (P12-17) critically depends on it. The P/Q-type voltage-dependent Ca(2+) channel in PCs triggers selective strengthening of single CF inputs, promotes dendritic translocation of the strengthened CFs, and drives the early phase of CF synapse elimination. In contrast, the late phase is mediated by the mGluR1-Gαq-PLCβ4-PKCγ signaling cascade in PCs driven at PF-PC synapses, whose structural connectivity is stabilized and maintained by the GluRδ2-Cbln1-neurexin system.

  5. Immuno-histochemistry and three-dimensional architecture of the intermediate filaments in Purkinje cells in mammalian hearts. (United States)

    Yoshimura, Akira; Yamaguchi, Takeshi; Kawazato, Hiroaki; Takahashi, Naohiko; Shimada, Tatsuo


    In mammalian hearts, Purkinje cells varied greatly in morphological appearance in different species, and were divided into three groups. Bovine Purkinje cells corresponding to group I were a large size, and had a few myofibrils and abundant intermediate filaments throughout the cytoplasm. The aim of the present study was to clarify the more detailed distribution and three-dimensional architecture of intermediate filaments in Purkinje cells. The hearts in various mammals including humans were investigated by both immuno-histochemistry and scanning electron microscopy (SEM).Immuno-histochemical studies demonstrated that sheep Purkinje cells in group I had a great number of intermediate filaments of 10 nm positive for desmin antibody. Purkinje cells in group II (humans, monkeys and dogs) and group III (mice) were somewhat larger or smaller in size than myocardial cells, but also showed a strong positive reaction for desmin antibody. The saponin or NaOH treatment of cardiac tissues in sheep and humans enabled us to view intermediate filaments by SEM three-dimensionally. Intermediate filaments in sheep Purkinje cells formed a considerably delicate network, and were distributed throughout the cytoplasm. In contrast, those in human Purkinje cells were lower in density, and were present around the nucleus and between myofibrils. It was concluded that a delicate network of intermediate filaments in Purkinje cells of mammalian hearts acted as the cytoskeleton to maintain intercellular stability.

  6. The role of Purkinje-myocardial coupling during ventricular arrhythmia: a modeling study. (United States)

    Behradfar, Elham; Nygren, Anders; Vigmond, Edward J


    The Purkinje system is the fast conduction network of the heart which couples to the myocardium at discrete sites called Purkinje-Myocyte Junctions (PMJs). However, the distribution and number of PMJs remains elusive, as does whether a particular PMJ is functional. We hypothesized that the Purkinje system plays a role during reentry and that the number of functional PMJs affect reentry dynamics. We used a computer finite element model of rabbit ventricles in which we varied the number of PMJs. Sustained, complex reentry was induced by applying an electric shock and the role of the Purkinje system in maintaining the arrhythmia was assessed by analyzing phase singularities, frequency of activation, and bidirectional propagation at PMJs. For larger junctional resistances, increasing PMJ density increased the mean firing rate in the Purkinje system, the percentage of successful retrograde conduction at PMJs, and the incidence of wave break on the epicardium. However, the mean firing of the ventricles was not affected. Furthermore, increasing PMJ density above 13/[Formula: see text] did not alter reentry dynamics. For lower junctional resistances, the trend was not as clear. We conclude that Purkinje system topology affects reentry dynamics and conditions which alter PMJ density can alter reentry dynamics.

  7. The role of Purkinje-myocardial coupling during ventricular arrhythmia: a modeling study.

    Directory of Open Access Journals (Sweden)

    Elham Behradfar

    Full Text Available The Purkinje system is the fast conduction network of the heart which couples to the myocardium at discrete sites called Purkinje-Myocyte Junctions (PMJs. However, the distribution and number of PMJs remains elusive, as does whether a particular PMJ is functional. We hypothesized that the Purkinje system plays a role during reentry and that the number of functional PMJs affect reentry dynamics. We used a computer finite element model of rabbit ventricles in which we varied the number of PMJs. Sustained, complex reentry was induced by applying an electric shock and the role of the Purkinje system in maintaining the arrhythmia was assessed by analyzing phase singularities, frequency of activation, and bidirectional propagation at PMJs. For larger junctional resistances, increasing PMJ density increased the mean firing rate in the Purkinje system, the percentage of successful retrograde conduction at PMJs, and the incidence of wave break on the epicardium. However, the mean firing of the ventricles was not affected. Furthermore, increasing PMJ density above 13/[Formula: see text] did not alter reentry dynamics. For lower junctional resistances, the trend was not as clear. We conclude that Purkinje system topology affects reentry dynamics and conditions which alter PMJ density can alter reentry dynamics.

  8. Activity-dependent accumulation of calcium in Purkinje cell dendritic spines.


    Andrews, S.B.; Leapman, R D; Landis, D M; Reese, T S


    The calcium content of synapses of parallel fibers on Purkinje cell dendritic spines was determined by electron probe x-ray microanalysis of freeze-dried cryosections from directly frozen slices of mouse cerebellar cortex. In fresh slices frozen within 20-30 sec of excision, calcium concentrations ranging from 0.8 to 18.6 mmol/kg of dry weight were measured in cisterns of smooth endoplasmic reticulum within Purkinje cell dendritic spines. The average calcium content of spine cisterns in rapid...

  9. Properties and expression of Kv3 channels in cerebellar Purkinje cells. (United States)

    Sacco, Tiziana; De Luca, Annarita; Tempia, Filippo


    In cerebellar Purkinje cells, Kv3 potassium channels are indispensable for firing at high frequencies. In Purkinje cells from young mice (P4-P7), Kv3 currents, recorded in whole-cell in slices, activated at -30 mV, with rapid activation and deactivation kinetics, and they were partially blocked by blood depressing substance-I (BDS-I, 1 microM). At positive potentials, Kv3 currents were slowly but completely inactivating, while the recovery from inactivation was about eightfold slower, suggesting that a previous firing activity or a small change of the resting potential could in principle accumulate inactivated Kv3 channels, thereby finely tuning Kv3 current availability for subsequent action potentials. Single-cell RT-PCR analysis showed the expression by all Purkinje cells (n=10 for each subunit) of Kv3.1, Kv3.3 and Kv3.4 mRNA, while Kv3.2 was not expressed. These results add to the framework for interpreting the physiological function and the molecular determinants of Kv3 currents in cerebellar Purkinje cells.

  10. Role of synchronous activation of cerebellar purkinje cell ensembles in multi-joint movement control

    NARCIS (Netherlands)

    T.M. Hoogland (Tycho); J.R. de Gruijl (Jornt); L. Witter (Laurens); M.I. Canto (Marcia Irene); C.I. de Zeeuw (Chris)


    textabstractIt is a longstanding question in neuroscience how elaborate multi-joint movements are coordinated coherently. Microzones of cerebellar Purkinje cells (PCs) are thought to mediate this coordination by controlling the timing of particular motor domains. However, it remains to be elucidated

  11. Role of Synchronous Activation of Cerebellar Purkinje Cell Ensembles in Multi-joint Movement Control

    NARCIS (Netherlands)

    Hoogland, Tycho M; De Gruijl, Jornt R; Witter, Laurens; Canto, Cathrin B; De Zeeuw, Chris I


    It is a longstanding question in neuroscience how elaborate multi-joint movements are coordinated coherently. Microzones of cerebellar Purkinje cells (PCs) are thought to mediate this coordination by controlling the timing of particular motor domains. However, it remains to be elucidated to what

  12. [Mathematical simulation of induction of long-term depression in cerebellar Purkinje cells]. (United States)

    Murzina, G B


    Mechanisms of associative and homosynaptic long-term depression (LTD) in cerebellar Purkinje cells are discussed. The possibility of LTD induction related to a decrease in efficacy of AMPA receptors through either their dephosphorylation or phosphorylation is investigated by mathematical simulation.

  13. Mathematical simulation of the induction of long-term depression in cerebellar Purkinje cells. (United States)

    Murzina, G B


    The question of the mechanisms underlying the induction of associative and homosynaptic long-term depression in cerebellar Purkinje cells is addressed. Mathematical simulation was used to investigate the possibility that long-term depression, which is associated with a decrease in the efficiency of AMPA receptors, could be induced both by phosphorylation and dephosphorylation of these receptors.

  14. Role of synchronous activation of cerebellar purkinje cell ensembles in multi-joint movement control

    NARCIS (Netherlands)

    T.M. Hoogland (Tycho); J.R. de Gruijl (Jornt); L. Witter (Laurens); M.I. Canto (Marcia Irene); C.I. de Zeeuw (Chris)


    textabstractIt is a longstanding question in neuroscience how elaborate multi-joint movements are coordinated coherently. Microzones of cerebellar Purkinje cells (PCs) are thought to mediate this coordination by controlling the timing of particular motor domains. However, it remains to be elucidated

  15. Role of Synchronous Activation of Cerebellar Purkinje Cell Ensembles in Multi-joint Movement Control

    NARCIS (Netherlands)

    Hoogland, Tycho M; De Gruijl, Jornt R; Witter, Laurens; Canto, Cathrin B; De Zeeuw, Chris I


    It is a longstanding question in neuroscience how elaborate multi-joint movements are coordinated coherently. Microzones of cerebellar Purkinje cells (PCs) are thought to mediate this coordination by controlling the timing of particular motor domains. However, it remains to be elucidated to what ext

  16. Mitochondrial fission protein Drp1 regulates mitochondrial transport and dendritic arborization in cerebellar Purkinje cells. (United States)

    Fukumitsu, Kansai; Hatsukano, Tetsu; Yoshimura, Azumi; Heuser, John; Fujishima, Kazuto; Kengaku, Mineko


    Mitochondria dynamically change their shape by repeated fission and fusion in response to physiological and pathological conditions. Recent studies have uncovered significant roles of mitochondrial fission and fusion in neuronal functions, such as neurotransmission and spine formation. However, the contribution of mitochondrial fission to the development of dendrites remains controversial. We analyzed the function of the mitochondrial fission GTPase Drp1 in dendritic arborization in cerebellar Purkinje cells. Overexpression of a dominant-negative mutant of Drp1 in postmitotic Purkinje cells enlarged and clustered mitochondria, which failed to exit from the soma into the dendrites. The emerging dendrites lacking mitochondrial transport remained short and unstable in culture and in vivo. The dominant-negative Drp1 affected neither the basal respiratory function of mitochondria nor the survival of Purkinje cells. Enhanced ATP supply by creatine treatment, but not reduced ROS production by antioxidant treatment, restored the hypomorphic dendrites caused by inhibition of Drp1 function. Collectively, our results suggest that Drp1 is required for dendritic distribution of mitochondria and thereby regulates energy supply in growing dendritic branches in developing Purkinje cells.

  17. Optogenetics in the cerebellum: Purkinje cell-specific approaches for understanding local cerebellar functions. (United States)

    Tsubota, Tadashi; Ohashi, Yohei; Tamura, Keita


    The cerebellum consists of the cerebellar cortex and the cerebellar nuclei. Although the basic neuronal circuitry of the cerebellar cortex is uniform everywhere, anatomical data demonstrate that the input and output relationships of the cortex are spatially segregated between different cortical areas, which suggests that there are functional distinctions between these different areas. Perturbation of cerebellar cortical functions in a spatially restricted fashion is thus essential for investigating the distinctions among different cortical areas. In the cerebellar cortex, Purkinje cells are the sole output neurons that send information to downstream cerebellar and vestibular nuclei. Therefore, selective manipulation of Purkinje cell activities, without disturbing other neuronal types and passing fibers within the cortex, is a direct approach to spatially restrict the effects of perturbations. Although this type of approach has for many years been technically difficult, recent advances in optogenetics now enable selective activation or inhibition of Purkinje cell activities, with high temporal resolution. Here we discuss the effectiveness of using Purkinje cell-specific optogenetic approaches to elucidate the functions of local cerebellar cortex regions. We also discuss what improvements to current methods are necessary for future investigations of cerebellar functions to provide further advances.

  18. A new approach for determining phase response curves reveals that Purkinje cells can act as perfect integrators.

    Directory of Open Access Journals (Sweden)

    Elena Phoka


    Full Text Available Cerebellar Purkinje cells display complex intrinsic dynamics. They fire spontaneously, exhibit bistability, and via mutual network interactions are involved in the generation of high frequency oscillations and travelling waves of activity. To probe the dynamical properties of Purkinje cells we measured their phase response curves (PRCs. PRCs quantify the change in spike phase caused by a stimulus as a function of its temporal position within the interspike interval, and are widely used to predict neuronal responses to more complex stimulus patterns. Significant variability in the interspike interval during spontaneous firing can lead to PRCs with a low signal-to-noise ratio, requiring averaging over thousands of trials. We show using electrophysiological experiments and simulations that the PRC calculated in the traditional way by sampling the interspike interval with brief current pulses is biased. We introduce a corrected approach for calculating PRCs which eliminates this bias. Using our new approach, we show that Purkinje cell PRCs change qualitatively depending on the firing frequency of the cell. At high firing rates, Purkinje cells exhibit single-peaked, or monophasic PRCs. Surprisingly, at low firing rates, Purkinje cell PRCs are largely independent of phase, resembling PRCs of ideal non-leaky integrate-and-fire neurons. These results indicate that Purkinje cells can act as perfect integrators at low firing rates, and that the integration mode of Purkinje cells depends on their firing rate.

  19. Ultrastructure of Purkinje cell perikarya and their dendritic processes in the rat cerebellar cortex in experimental encephalopathy induced by chronic application of valproate. (United States)

    Sobaniec-Lotowska, M E


    Long-term intragastric administration of the antiepileptic drug sodium valproate (Vuprol Polfa) to rats for 1, 3, 6, 9 and 12 months, once daily at the effective dose of 200 mg/kg body weight showed morphological evidence of encephalopathy, manifested by numerous nonspecific changes within Purkinje cell perikarya and their dendritic processes. The first ultrastructural abnormalities appeared after 3 months. They became more severe in animals with longer survival and were most pronounced after 12 months. The changes were maintained both 1 and 3 months after drug withdrawal. Mitochondria of Purkinje cell perikarya were most severely affected. Damage to mitochondria was accompanied by disintegration and fragmentation of granular endoplasmic reticulum, dilation of channels and cisterns of Golgi apparatus, enlargement of smooth endoplasmic reticulum elements including submembranous cisterns, and accumulation of profuse lipofuscin deposits. Frequently, Purkinje cells appeared as dark ischemic neurones, with focally damaged cellular membrane and features of disintegration. Swollen Bergmann's astrocytes were seen among damaged Purkinje cells or at the site of their loss. The general pattern of submicroscopic alterations of Purkinje cell perikarya suggested severe disorders in several intercellular biochemical extents, including inhibition of oxidative phosphorylation and abnormal protein synthesis, both of which could lead to lethal damage. Ultrastructural abnormalities within dendrites were characterized by damage to elements of smooth endoplasmic reticulum, which was considerably enlarged, with formation of large vacuolar structures situated deep in the dendroplasm. Mitochondrial lesions and alterations in cytoskeletal elements--disintegration of microtubules or even their complete loss--were also observed. The general pattern of abnormalities within the organelles and cytoskeletal elements of dendritic processes in Purkinje cells in the VPA chronic experimental model

  20. Cadm1-expressing synapses on Purkinje cell dendrites are involved in mouse ultrasonic vocalization activity.

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    Eriko Fujita

    Full Text Available Foxp2(R552H knock-in (KI mouse pups with a mutation related to human speech-language disorders exhibit poor development of cerebellar Purkinje cells and impaired ultrasonic vocalization (USV, a communication tool for mother-offspring interactions. Thus, human speech and mouse USV appear to have a Foxp2-mediated common molecular basis in the cerebellum. Mutations in the gene encoding the synaptic adhesion molecule CADM1 (RA175/Necl2/SynCAM1/Cadm1 have been identified in people with autism spectrum disorder (ASD who have impaired speech and language. In the present study, we show that both Cadm1-deficient knockout (KO pups and Foxp2(R552H KI pups exhibit impaired USV and smaller cerebellums. Cadm1 was preferentially localized to the apical-distal portion of the dendritic arbor of Purkinje cells in the molecular layer of wild-type pups, and VGluT1 level decreased in the cerebellum of Cadm1 KO mice. In addition, we detected reduced immunoreactivity of Cadm1 and VGluT1 on the poorly developed dendritic arbor of Purkinje cells in the Foxp2(R552H KI pups. However, Cadm1 mRNA expression was not altered in the Foxp2(R552H KI pups. These results suggest that although the Foxp2 transcription factor does not target Cadm1, Cadm1 at the synapses of Purkinje cells and parallel fibers is necessary for USV function. The loss of Cadm1-expressing synapses on the dendrites of Purkinje cells may be associated with the USV impairment that Cadm1 KO and Foxp2(R552H KI mice exhibit.

  1. Mesenchymal stem cell transplantation ameliorates motor function deterioration of spinocerebellar ataxia by rescuing cerebellar Purkinje cells

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    Ma Wei-Hsien


    Full Text Available Abstract Background Spinocerebellar ataxia (SCA refers to a disease entity in which polyglutamine aggregates are over-produced in Purkinje cells (PCs of the cerebellum as well as other neurons in the central nervous system, and the formation of intracellular polyglutamine aggregates result in the loss of neurons as well as deterioration of motor functions. So far there is no effective neuroprotective treatment for this debilitating disease although numerous efforts have been made. Mesenchymal stem cells (MSCs possess multi-lineage differentiation potentials as well as immuno-modulatory properties, and are theoretically good candidates for SCA treatment. The purpose of this study is to investigate whether transplantation of human MSCs (hMSCs can rescue cerebellar PCs and ameliorate motor function deterioration in SCA in a pre-clinical animal model. Method Transgenic mice bearing poly-glutamine mutation in ataxin-2 gene (C57BL/6J SCA2 transgenic mice were serially transplanted with hMSCs intravenously or intracranially before and after the onset of motor function loss. Motor function of mice was evaluated by an accelerating protocol of rotarod test every 8 weeks. Immunohistochemical stain of whole brain sections was adopted to demonstrate the neuroprotective effect of hMSC transplantation on cerebellar PCs and engraftment of hMSCs into mice brain. Results Intravenous transplantation of hMSCs effectively improved rotarod performance of SCA2 transgenic mice and delayed the onset of motor function deterioration; while intracranial transplantation failed to achieve such neuroprotective effect. Immunohistochemistry revealed that intravenous transplantation was more effective in the preservation of the survival of cerebellar PCs and engraftment of hMSCs than intracranial injection, which was compatible to rotarod performance of transplanted mice. Conclusion Intravenous transplantation of hMSCs can indeed delay the onset as well as improve the motor

  2. Acid-sensitive channel inhibition prevents fetal alcohol spectrum disorders cerebellar Purkinje cell loss. (United States)

    Ramadoss, Jayanth; Lunde, Emilie R; Ouyang, Nengtai; Chen, Wei-Jung A; Cudd, Timothy A


    Ethanol is now considered the most common human teratogen. Educational campaigns have not reduced the incidence of ethanol-mediated teratogenesis, leading to a growing interest in the development of therapeutic prevention or mitigation strategies. On the basis of the observation that maternal ethanol consumption reduces maternal and fetal pH, we hypothesized that a pH-sensitive pathway involving the TWIK-related acid-sensitive potassium channels (TASKs) is implicated in ethanol-induced injury to the fetal cerebellum, one of the most sensitive targets of prenatal ethanol exposure. Pregnant ewes were intravenously infused with ethanol (258+/-10 mg/dl peak blood ethanol concentration) or saline in a "3 days/wk binge" pattern throughout the third trimester. Quantitative stereological analysis demonstrated that ethanol resulted in a 45% reduction in the total number of fetal cerebellar Purkinje cells, the cell type most sensitive to developmental ethanol exposure. Extracellular pH manipulation to create the same degree and pattern of pH fall caused by ethanol (manipulations large enough to inhibit TASK 1 channels), resulted in a 24% decrease in Purkinje cell number. We determined immunohistochemically that TASK 1 channels are expressed in Purkinje cells and that the TASK 3 isoform is expressed in granule cells of the ovine fetal cerebellum. Pharmacological blockade of both TASK 1 and TASK 3 channels simultaneous with ethanol effectively prevented any reduction in fetal cerebellar Purkinje cell number. These results demonstrate for the first time functional significance of fetal cerebellar two-pore domain pH-sensitive channels and establishes them as a potential therapeutic target for prevention of ethanol teratogenesis.

  3. Diacylglycerol kinase ε localizes to subsurface cisterns of cerebellar Purkinje cells. (United States)

    Hozumi, Yasukazu; Fujiwara, Hiroki; Kaneko, Kenya; Fujii, Satoshi; Topham, Matthew K; Watanabe, Masahiko; Goto, Kaoru


    Following activation of Gq protein-coupled receptors, phospholipase C yields a pair of second messengers: diacylglycerol (DG) and inositol 1,4,5-trisphosphate. Diacylglycerol kinase (DGK) phosphorylates DG to produce phosphatidic acid, another second messenger. Of the DGK family, DGKε is the only DGK isoform that exhibits substrate specificity for DG with an arachidonoyl acyl chain at the sn-2 position. Recently, we demonstrated that hydrophobic residues in the N-terminus of DGKε play an important role in targeting the endoplasmic reticulum in transfected cells. However, its cellular expression and subcellular localization in the brain remain elusive. In the present study, we investigate this issue using specific DGKε antibody. DGKε was richly expressed in principal neurons of higher brain regions, including pyramidal cells in the hippocampus and neocortex, medium spiny neurons in the striatum and Purkinje cells in the cerebellum. In Purkinje cells, DGKε was localized to the subsurface cisterns and colocalized with inositol 1,4,5-trisphosphate receptor-1 in dendrites and axons. In dendrites of Purkinje cells, DGKε was also distributed in close apposition to DG lipase-α, which catalyzes arachidonoyl-DG to produce 2-arachidonoyl glycerol, a major endocannabinoid in the brain. Behaviorally, DGKε-knockout mice exhibited hyper-locomotive activities and impaired motor coordination and learning. These findings suggest that DGKε plays an important role in neuronal and brain functions through its distinct neuronal expression and subcellular localization and also through coordinated arrangement with other molecules involving the phosphoinositide signaling pathway.

  4. Alcohol Impairs Long-Term Depression at the Cerebellar Parallel Fiber–Purkinje Cell Synapse (United States)

    Belmeguenai, Amor; Botta, Paolo; Weber, John T.; Carta, Mario; De Ruiter, Martijn; De Zeeuw, Chris I.; Valenzuela, C. Fernando; Hansel, Christian


    Acute alcohol consumption causes deficits in motor coordination and gait, suggesting an involvement of cerebellar circuits, which play a role in the fine adjustment of movements and in motor learning. It has previously been shown that ethanol modulates inhibitory transmission in the cerebellum and affects synaptic transmission and plasticity at excitatory climbing fiber (CF) to Purkinje cell synapses. However, it has not been examined thus far how acute ethanol application affects long-term depression (LTD) and long-term potentiation (LTP) at excitatory parallel fiber (PF) to Purkinje cell synapses, which are assumed to mediate forms of cerebellar motor learning. To examine ethanol effects on PF synaptic transmission and plasticity, we performed whole cell patch-clamp recordings from Purkinje cells in rat cerebellar slices. We found that ethanol (50 mM) selectively blocked PF–LTD induction, whereas it did not change the amplitude of excitatory postsynaptic currents at PF synapses. In contrast, ethanol application reduced voltage-gated calcium currents and type 1 metabotropic glutamate receptor (mGluR1)–dependent responses in Purkinje cells, both of which are involved in PF–LTD induction. The selectivity of these effects is emphasized by the observation that ethanol did not impair PF–LTP and that PF–LTP could readily be induced in the presence of the group I mGluR antagonist AIDA or the mGluR1a antagonist LY367385. Taken together, these findings identify calcium currents and mGluR1-dependent signaling pathways as potential ethanol targets and suggest that an ethanol-induced blockade of PF–LTD could contribute to the motor coordination deficits resulting from alcohol consumption. PMID:18922952

  5. Activation of a Temporal Memory in Purkinje Cells by the mGluR7 Receptor

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    Fredrik Johansson


    Full Text Available Cerebellar Purkinje cells can learn to respond to a conditioned stimulus with an adaptively timed pause in firing. This response was usually ascribed to long-term depression of parallel fiber to Purkinje cell synapses but has recently been shown to be due to a previously unknown form of learning involving an intrinsic cellular timing mechanism. Here, we investigate how these responses are elicited. They are resistant to blockade of GABAergic inhibition, suggesting that they are caused by glutamate release rather than by a changed balance between GABA and glutamate. We show that the responses are abolished by antagonists of the mGlu7 receptor but not significantly affected by other glutamate antagonists. These results support the existence of a distinct learning mechanism, different from changes in synaptic strength. They also demonstrate in vivo post-synaptic inhibition mediated by glutamate and show that the mGlu7 receptor is involved in activating intrinsic temporal memory.

  6. Purkinje-like cells of the rat cochlear nucleus: a combined functional and morphological study


    Kőszeghy Áron (1983-) (Ph.D hallgató, élettanász); Pál Balázs (1975-) (élettanász); Pap Pál (1981-) (élettanász); Pocsai Krisztina (1978-) (élettanász); Nagy Zsuzsanna (1986-) (élettanász); Szűcs Géza (1948-) (élettanász); Rusznák Zoltán (1965-) (élettanász)


    Purkinje-like cells (PLCs) of the cochlear nucleus (CN) are strongly calbindin positive neurones with unknown function. In the present work functional and morphological methods have been employed to provide data about PLCs in general, and about their possible involvement in the synaptic organisation of the CN in particular. PLCs had slightly elongated soma, from which a complex dendritic arborisation extended with highly variable dimensions. On the basis of their morphology, three classes of ...

  7. Parametric study of the Noble's action potential model for cardiac Purkinje fibers

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    Wang, P.K.C. [Department of Electrical Engineering, University of California, Los Angeles, CA 90095-1594 (United States); Kogan, B.Y. [Department of Computer Science, University of California, Los Angeles, CA 90095-1594 (United States)]. E-mail:


    The effect of parameter variation on repolarization processes in the Noble model (Hodjkin-Huxley type) for action potential (AP) generation in Purkinje cells is studied using a combination of computer simulation and nonlinear dynamic system theory including Hopf bifurcation analysis. Both the original Noble model and a simplified Noble model are used in this study. It is shown that these models have similar qualitative dynamic behavior in the presence of parameter variations. In particular, it is demonstrated that both normal and abnormal modes of cell performance can be obtained by varying the potassium and anion conductances. The abnormal mode (cardiac arrest) may play a significant role in disorganizing the electrical activities in the heart muscles. The existence of Hopf bifurcation with respect to variations in the anion conductance and fixed values of potassium conductances is studied in detail. The regions corresponding to spontaneous AP excitation, and various types of cardiac arrest in the ion-conductance parameter space of both full and simplified Noble models with and without external stimuli are mapped out using computer simulation.

  8. SK2 channel modulation contributes to compartment-specific dendritic plasticity in cerebellar Purkinje cells. (United States)

    Ohtsuki, Gen; Piochon, Claire; Adelman, John P; Hansel, Christian


    Small-conductance Ca(2+)-activated K(+) channels (SK channels) modulate excitability and curtail excitatory postsynaptic potentials (EPSPs) in neuronal dendrites. Here, we demonstrate long-lasting plasticity of intrinsic excitability (IE) in dendrites that results from changes in the gain of this regulatory mechanism. Using dendritic patch-clamp recordings from rat cerebellar Purkinje cells, we find that somatic depolarization or parallel fiber (PF) burst stimulation induce long-term amplification of synaptic responses to climbing fiber (CF) or PF stimulation and enhance the amplitude of passively propagated sodium spikes. Dendritic plasticity is mimicked and occluded by the SK channel blocker apamin and is absent in Purkinje cells from SK2 null mice. Triple-patch recordings from two dendritic sites and the soma and confocal calcium imaging studies show that local stimulation limits dendritic plasticity to the activated compartment of the dendrite. This plasticity mechanism allows Purkinje cells to adjust the SK2-mediated control of dendritic excitability in an activity-dependent manner.

  9. The Phospholipase D2 Knock Out Mouse Has Ectopic Purkinje Cells and Suffers from Early Adult-Onset Anosmia (United States)

    Zhang, Qifeng; Smethurst, Elizabeth; Segonds-Pichon, Anne; Schrewe, Heinrich; Wakelam, Michael J. O.


    Phospholipase D2 (PLD2) is an enzyme that produces phosphatidic acid (PA), a lipid messenger molecule involved in a number of cellular events including, through its membrane curvature properties, endocytosis. The PLD2 knock out (PLD2KO) mouse has been previously reported to be protected from insult in a model of Alzheimer's disease. We have further analysed a PLD2KO mouse using mass spectrophotometry of its lipids and found significant differences in PA species throughout its brain. We have examined the expression pattern of PLD2 which allowed us to define which region of the brain to analyse for defect, notably PLD2 was not detected in glial-rich regions. The expression pattern lead us to specifically examine the mitral cells of olfactory bulbs, the Cornus Amonis (CA) regions of the hippocampus and the Purkinje cells of the cerebellum. We find that the change to longer PA species correlates with subtle architectural defect in the cerebellum, exemplified by ectopic Purkinje cells and an adult-onset deficit of olfaction. These observations draw parallels to defects in the reelin heterozygote as well as the effect of high fat diet on olfaction. PMID:27658289

  10. The ionic bases of the action potential in isolated mouse cardiac Purkinje cell. (United States)

    Vaidyanathan, Ravi; O'Connell, Ryan P; Deo, Makarand; Milstein, Michelle L; Furspan, Philip; Herron, Todd J; Pandit, Sandeep V; Musa, Hassan; Berenfeld, Omer; Jalife, José; Anumonwo, Justus M B


    Collecting electrophysiological and molecular data from the murine conduction system presents technical challenges. Thus, only little advantage has been taken of numerous genetically engineered murine models to study excitation through the cardiac conduction system of the mouse. To develop an approach for isolating murine cardiac Purkinje cells (PCs), to characterize major ionic currents and to use the data to simulate action potentials (APs) recorded from PCs. Light microscopy was used to isolate and identify PCs from apical and septal cells. Current and voltage clamp techniques were used to record APs and whole cell currents. We then simulated a PC AP on the basis of our experimental data. APs recorded from PCs were significantly longer than those recorded from ventricular cells. The prominent plateau phase of the PC AP was very negative (≈-40 mV). Spontaneous activity was observed only in PCs. The inward rectifier current demonstrated no significant differences compared to ventricular myocytes (VMs). However, sodium current density was larger, and the voltage-gated potassium current density was significantly less in PCs compared with myocytes. T-type Ca(2+) currents (I(Ca,T)) were present in PCs but not VMs. Computer simulations suggest that I(Ca,T) and cytosolic calcium diffusion significantly modulate AP profile recorded in PCs, as compared to VMs. Our study provides the first comprehensive ionic profile of murine PCs. The data show unique features of PC ionic mechanisms that govern its excitation process. Experimental data and numerical modeling results suggest that a smaller voltage-gated potassium current and the presence of I(Ca,T) are important determinants of the longer and relatively negative plateau phase of the APs. Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  11. The ins and outs of GluD2--why and how Purkinje cells use the special glutamate receptor. (United States)

    Yuzaki, Michisuke


    The δ2 glutamate receptor (GluD2) is predominantly expressed in cerebellar Purkinje cells and plays crucial roles in cerebellar functions. Indeed, the number of synapses between parallel fibers (PFs) and Purkinje cells is specifically and severely reduced in GluD2-null cerebellum. In addition, long-term depression (LTD) at PF-Purkinje cell synapses is impaired in these mice. Nevertheless, the mechanism by which GluD2 regulate these two functions-morphological and functional synaptic plasticity at PF synapses-has remained unclear. Recently, we found that Cbln1, a glycoprotein released from granule cells, was bound to the N-terminal domain of GluD2 and regulated formation and maintenance of PF-Purkinje cell synapses. Furthermore, we found that D: -Ser released from Bergmann glia bound the ligand-binding domain of GluD2 and mediated LTD in a manner dependent on the C-terminus. These findings indicate how GluD2 is activated and regulates functions at PF-Purkinje cell synapses. A hypothesis about why GluD2 is employed by PF synapses is also discussed.

  12. Kv3 K+ channels enable burst output in rat cerebellar Purkinje cells. (United States)

    McKay, B E; Turner, R W


    The ability of cells to generate an appropriate spike output depends on a balance between membrane depolarizations and the repolarizing actions of K(+) currents. The high-voltage-activated Kv3 class of K(+) channels repolarizes Na(+) spikes to maintain high frequencies of discharge. However, little is known of the ability for these K(+) channels to shape Ca(2+) spike discharge or their ability to regulate Ca(2+) spike-dependent burst output. Here we identify the role of Kv3 K(+) channels in the regulation of Na(+) and Ca(2+) spike discharge, as well as burst output, using somatic and dendritic recordings in rat cerebellar Purkinje cells. Kv3 currents pharmacologically isolated in outside-out somatic membrane patches accounted for approximately 40% of the total K(+) current, were very fast and high voltage activating, and required more than 1 s to fully inactivate. Kv3 currents were differentiated from other tetraethylammonium-sensitive currents to establish their role in Purkinje cells under physiological conditions with current-clamp recordings. Dual somatic-dendritic recordings indicated that Kv3 channels repolarize Na(+) and Ca(2+) spikes, enabling high-frequency discharge for both types of cell output. We further show that during burst output Kv3 channels act together with large-conductance Ca(2+)-activated K(+) channels to ensure an effective coupling between Ca(2+) and Na(+) spike discharge by preventing Na(+) spike inactivation. By contributing significantly to the repolarization of Na(+) and especially Ca(2+) spikes, our data reveal a novel function for Kv3 K(+) channels in the maintenance of high-frequency burst output for cerebellar Purkinje cells.

  13. Cerebellar transcriptional alterations with Purkinje cell dysfunction and loss in mice lacking PGC-1α (United States)

    Lucas, Elizabeth K.; Reid, Courtney S.; McMeekin, Laura J.; Dougherty, Sarah E.; Floyd, Candace L.; Cowell, Rita M.


    Alterations in the expression and activity of the transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator-1α (ppargc1a or PGC-1α) have been reported in multiple movement disorders, yet it is unclear how a lack of PGC-1α impacts transcription and function of the cerebellum, a region with high PGC-1α expression. We show here that mice lacking PGC-1α exhibit ataxia in addition to the previously described deficits in motor coordination. Using q-RT-PCR in cerebellar homogenates from PGC-1α−/− mice, we measured expression of 37 microarray-identified transcripts upregulated by PGC-1α in SH-SY5Y neuroblastoma cells with neuroanatomical overlap with PGC-1α or parvalbumin (PV), a calcium buffer highly expressed by Purkinje cells. We found significant reductions in transcripts with synaptic (complexin1, Cplx1; Pacsin2), structural (neurofilament heavy chain, Nefh), and metabolic (isocitrate dehydrogenase 3a, Idh3a; neutral cholesterol ester hydrolase 1, Nceh1; pyruvate dehydrogenase alpha 1, Pdha1; phytanoyl-CoA hydroxylase, Phyh; ubiquinol-cytochrome c reductase, Rieske iron-sulfur polypeptide 1, Uqcrfs1) functions. Using conditional deletion of PGC-1α in PV-positive neurons, we determined that 50% of PGC-1α expression and a reduction in a subset of these transcripts could be explained by its concentration in PV-positive neuronal populations in the cerbellum. To determine whether there were functional consequences associated with these changes, we conducted stereological counts and spike rate analysis in Purkinje cells, a cell type rich in PV, from PGC-1α−/− mice. We observed a significant loss of Purkinje cells by 6 weeks of age, and the remaining Purkinje cells exhibited a 50% reduction in spike rate. Together, these data highlight the complexity of PGC-1α's actions in the central nervous system and suggest that dysfunction in multiple cell types contribute to motor deficits in the context of PGC-1α deficiency. PMID

  14. Cerebellar transcriptional alterations with Purkinje cell dysfunction and loss in mice lacking PGC-1α

    Directory of Open Access Journals (Sweden)

    Elizabeth K Lucas


    Full Text Available Alterations in the expression and activity of the transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator-1α (ppargc1a or PGC-1α have been reported in multiple movement disorders, yet it is unclear how a lack of PGC-1α impacts transcription and function of the cerebellum, a region with high PGC-1α expression. We show here that mice lacking PGC-1α exhibit ataxia in addition to the previously described deficits in motor coordination. Using q-RT-PCR in cerebellar homogenates from PGC-1α -/- mice, we measured expression of 37 microarray-identified transcripts upregulated by PGC-1α in SH-SY5Y neuroblastoma cells with neuroanatomical overlap with PGC-1α or parvalbumin (PV, a calcium buffer highly expressed by Purkinje cells. We found significant reductions in transcripts with synaptic (complexin1, Cplx1; Pacsin2, structural (neurofilament heavy chain, Nefh, and metabolic (isocitrate dehydrogenase 3a, Idh3a; neutral cholesterol ester hydrolase 1, Nceh1; pyruvate dehydrogenase alpha 1, Pdha1; phytanoyl-CoA hydroxylase, Phyh; ubiquinol-cytochrome c reductase, Rieske iron-sulfur polypeptide 1, Uqcrfs1 functions. Using conditional deletion of PGC-1α in PV-positive neurons, we determined that 50% of PGC-1α expression and a reduction in a subset of these transcripts could be explained by its concentration in PV-positive neuronal populations in the cerbellum. To determine whether there were functional consequences associated with these changes, we conducted stereological counts and spike rate analysis in Purkinje cells, a cell type rich in PV, from PGC-1α -/- mice. We observed a significant loss of Purkinje cells by six weeks of age, and the remaining Purkinje cells exhibited a 50% reduction in spike rate. Together, these data highlight the complexity of PGC-1α’s actions in the central nervous system and suggest that dysfunction in multiple cell types contribute to motor deficits in the context of PGC-1α deficiency.

  15. Alterações quantitativas das células de purkinje na moléstia de chagas experimental no camundongo Quantitative study of Purkinje cells in the acute phase of experimental Chagas' disease

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    Edymar Jardim


    Full Text Available O autor estudou quantitativamente as células de Purkinje em cortes semi-seriados do cerebelo de camundongos inoculados experimentalmente com T. cruzi,tendo verificado considerável destruição neuronal na fase aguda da enfermidade.A quantitative study of Purkinje cells was done through semi-serial sections of cerebellum of mice experimentally innoculated by Trypanosoma cruzi. Avery marked neuronal destruction was found in the acute phase of Chagas' disease.

  16. Cbln1 binds to specific postsynaptic sites at parallel fiber-Purkinje cell synapses in the cerebellum. (United States)

    Matsuda, Keiko; Kondo, Tetsuro; Iijima, Takatoshi; Matsuda, Shinji; Watanabe, Masahiko; Yuzaki, Michisuke


    Cbln1, which belongs to the C1q/tumor necrosis factor superfamily, is a unique molecule that is not only required for maintaining normal parallel fiber (PF)-Purkinje cell synapses, but is also capable of inducing new PF synapses in adult cerebellum. Although Cbln1 is reportedly released from granule cells, where and how Cbln1 binds in the cerebellum has remained largely unclear, partly because Cbln1 undergoes proteolysis to yield various fragments that are differentially detected by different antibodies. To circumvent this problem, we characterized the Cbln1-binding site using recombinant Cbln1. An immunohistochemical analysis revealed that recombinant Cbln1 preferentially bound to PF-Purkinje cell synapses in primary cultures and acute slice preparations in a saturable and replaceable manner. Specific binding was observed for intact Cbln1 that had formed a hexamer, but not for the N-terminal or C-terminal fragments of Cbln1 fused to other proteins. Similarly, mutant Cbln1 that had formed a trimer did not bind to the Purkinje cells. Immunoreactivity for the recombinant Cbln1 was observed in weaver cerebellum (which lacks granule cells) but was absent in pcd cerebellum (which lacks Purkinje cells), suggesting that the binding site was located on the postsynaptic sites of PF-Purkinje cell synapses. Finally, a subcellular fractionation analysis revealed that recombinant Cbln1 bound to the synaptosomal and postsynaptic density fractions. These results indicate that Cbln1, released from granule cells as hexamers, specifically binds to a putative receptor located at the postsynaptic sites of PF-Purkinje cell synapses, where it induces synaptogenesis.

  17. Rapid development of Purkinje cell excitability, functional cerebellar circuit, and afferent sensory input to cerebellum in zebrafish. (United States)

    Hsieh, Jui-Yi; Ulrich, Brittany; Issa, Fadi A; Wan, Jijun; Papazian, Diane M


    The zebrafish has significant advantages for studying the morphological development of the brain. However, little is known about the functional development of the zebrafish brain. We used patch clamp electrophysiology in live animals to investigate the emergence of excitability in cerebellar Purkinje cells, functional maturation of the cerebellar circuit, and establishment of sensory input to the cerebellum. Purkinje cells are born at 3 days post-fertilization (dpf). By 4 dpf, Purkinje cells spontaneously fired action potentials in an irregular pattern. By 5 dpf, the frequency and regularity of tonic firing had increased significantly and most cells fired complex spikes in response to climbing fiber activation. Our data suggest that, as in mammals, Purkinje cells are initially innervated by multiple climbing fibers that are winnowed to a single input. To probe the development of functional sensory input to the cerebellum, we investigated the response of Purkinje cells to a visual stimulus consisting of a rapid change in light intensity. At 4 dpf, sudden darkness increased the rate of tonic firing, suggesting that afferent pathways carrying visual information are already active by this stage. By 5 dpf, visual stimuli also activated climbing fibers, increasing the frequency of complex spiking. Our results indicate that the electrical properties of zebrafish and mammalian Purkinje cells are highly conserved and suggest that the same ion channels, Nav1.6 and Kv3.3, underlie spontaneous pacemaking activity. Interestingly, functional development of the cerebellum is temporally correlated with the emergence of complex, visually-guided behaviors such as prey capture. Because of the rapid formation of an electrically-active cerebellum, optical transparency, and ease of genetic manipulation, the zebrafish has great potential for functionally mapping cerebellar afferent and efferent pathways and for investigating cerebellar control of motor behavior.

  18. The postnatal development of cerebellar Purkinje cells in the Gottingen minipig estimated with a new stereological sampling technique--the vertical bar fractionator

    DEFF Research Database (Denmark)

    Jelsing, Jacob; Gundersen, Hans Jørgen Gottlieb; Nielsen, Rune;


    demonstrates that a pronounced postnatal neurogenesis in Purkinje cell number and perikaryon volume is part of the growth and development of the cerebellum in the Gottingen minipig. The Purkinje cells of the Gottingen minipig were found to be substantially large compared with human and represents the largest...

  19. Deranged calcium signaling in Purkinje cells and pathogenesis in spinocerebellar ataxia 2 (SCA2) and other ataxias. (United States)

    Kasumu, Adebimpe; Bezprozvanny, Ilya


    Spinocerebellar ataxias (SCAs) constitute a heterogeneous group of more than 30 autosomal-dominant genetic and neurodegenerative disorders. SCAs are generally characterized by progressive ataxia and cerebellar atrophy. Although all SCA patients present with the phenotypic overlap of cerebellar atrophy and ataxia, 17 different gene loci have so far been implicated as culprits in these SCAs. It is not currently understood how mutations in these 17 proteins lead to the cerebellar atrophy and ataxia. Several pathogenic mechanisms have been studied in SCAs but there is yet to be a promising target for successful treatment of SCAs. Emerging research suggests that a fundamental cellular signaling pathway is disrupted by a majority of these mutated genes, which could explain the characteristic death of Purkinje cells, cerebellar atrophy, and ataxia that occur in many SCAs. We propose that mutations in SCA genes cause disruptions in multiple cellular pathways but the characteristic SCA pathogenesis does not begin until calcium signaling pathways are disrupted in cerebellar Purkinje cells either as a result of an excitotoxic increase or a compensatory suppression of calcium signaling. We argue that disruptions in Purkinje cell calcium signaling lead to initial cerebellar dysfunction and ataxic sympoms and eventually proceed to Purkinje cell death. Here, we discuss a calcium hypothesis of Purkinje cell neurodegeneration in SCAs by primarily focusing on an example of spinocerebellar ataxia 2 (SCA2). We will also present evidence linking deranged calcium signaling to the pathogenesis of other SCAs (SCA1, 3, 5, 6, 14, 15/16) that lead to significant Purkinje cell dysfunction and loss in patients.

  20. Effect of treadmill exercise on Purkinje cell loss and astrocytic reaction in the cerebellum after traumatic brain injury. (United States)

    Seo, Tae-Beom; Kim, Bo-Kyun; Ko, Il-Gyu; Kim, Dong-Hyun; Shin, Mal-Soon; Kim, Chang-Ju; Yoon, Jin-Hwan; Kim, Hong


    The cerebellum is one of the brain areas, which is selectively vulnerable to forebrain traumatic brain injuries (TBI). Physical exercise in animals is known to promote cell survival and functional recovery after brain injuries. However, the detailed pathologic and functional alterations by exercise following an indirect cerebellar injury induced by a TBI are largely unknown. We determined the effects of treadmill exercise on survival of Purkinje neurons and on a population of reactive astrocytes in the gyrus of lobules VIII and IX of the cerebellum after TBI. The rats were divided into four groups: the sham-operation group, the sham-operation with exercise group, the TBI-induction group, and the TBI-induction with exercise group. Cell biological changes of Purkinje neurons following indirect cerebellar injury were analyzed by immunohistochemistry. TBI-induced loss of calbindin-stained Purkinje neurons in the posterior region of the cerebellum and TBI also increased formation of reactive astroyctes in both the granular and molecular layers of the cerebellar posterior region. Treadmill exercise for 10 days after TBI increased the number of calbindin-stained Purkinje neurons and suppressed formation of reactive astroyctes. The present study provides the possibility that treadmill exercise may be an important mediator to enhance survival of Purkinje neurons in TBI-induced indirect cerebellar injury.

  1. Interneuron- and GABAA receptor-specific inhibitory synaptic plasticity in cerebellar Purkinje cells (United States)

    He, Qionger; Duguid, Ian; Clark, Beverley; Panzanelli, Patrizia; Patel, Bijal; Thomas, Philip; Fritschy, Jean-Marc; Smart, Trevor G.


    Inhibitory synaptic plasticity is important for shaping both neuronal excitability and network activity. Here we investigate the input and GABAA receptor subunit specificity of inhibitory synaptic plasticity by studying cerebellar interneuron-Purkinje cell (PC) synapses. Depolarizing PCs initiated a long-lasting increase in GABA-mediated synaptic currents. By stimulating individual interneurons, this plasticity was observed at somatodendritic basket cell synapses, but not at distal dendritic stellate cell synapses. Basket cell synapses predominantly express β2-subunit-containing GABAA receptors; deletion of the β2-subunit ablates this plasticity, demonstrating its reliance on GABAA receptor subunit composition. The increase in synaptic currents is dependent upon an increase in newly synthesized cell surface synaptic GABAA receptors and is abolished by preventing CaMKII phosphorylation of GABAA receptors. Our results reveal a novel GABAA receptor subunit- and input-specific form of inhibitory synaptic plasticity that regulates the temporal firing pattern of the principal output cells of the cerebellum.

  2. Purkinje Cells as Sources of Arrhythmias in Long QT Syndrome Type 3. (United States)

    Iyer, Vivek; Roman-Campos, Danilo; Sampson, Kevin J; Kang, Guoxin; Fishman, Glenn I; Kass, Robert S


    Long QT syndrome (LQTS) is characterized by ventricular arrhythmias and sudden cardiac death. Purkinje cells (PC) within the specialized cardiac conduction system have unique electrophysiological properties that we hypothesize may produce the primary sources of arrhythmia in heritable LQTS. LQTS type 3 (LQT3) transgenic mice harboring the ΔKPQ(+/-) mutation were crossed with Contactin2-EGFP BAC transgenic mice, which express a fluorescent reporter gene within the Purkinje fiber network. Isolated ventricular myocytes (VMs) (EGFP(-)) and PCs (EGFP(+)) from wild type and ΔKPQ mutant hearts were compared using the whole-cell patch clamp technique and microfluorimetry of calcium transients. Increased late sodium current was seen in ΔKPQ-PCs and ΔKPQ-VMs, with larger density in ΔKPQ-PCs. Marked prolongation of action potential duration of ΔKPQ-PCs was seen compared to ΔKPQ-VMs. ΔKPQ-PCs, but not ΔKPQ-VMs, exhibited frequent early afterdepolarizations, which corresponded to repetitive oscillations of intracellular calcium. Abnormalities in cell repolarization were reversed with exposure to mexiletine. We present the first direct experimental evidence that PCs are uniquely sensitive to LQT3 mutations, displaying electrophysiological behavior that is highly pro-arrhythmic.

  3. Purkinje-like cells of the rat cochlear nucleus: a combined functional and morphological study. (United States)

    Koszeghy, Aron; Pál, Balázs; Pap, Pál; Pocsai, Krisztina; Nagy, Zsuzsanna; Szucs, Géza; Rusznák, Zoltán


    Purkinje-like cells (PLCs) of the cochlear nucleus (CN) are strongly calbindin positive neurones with unknown function. In the present work functional and morphological methods have been employed to provide data about PLCs in general, and about their possible involvement in the synaptic organisation of the CN in particular. PLCs had slightly elongated soma, from which a complex dendritic arborisation extended with highly variable dimensions. On the basis of their morphology, three classes of PLCs were identified. Positively identified PLCs fired a train of action potentials on sustained depolarization. When hyperpolarizing stimuli were applied, the presence of a slowly activating, ZD7288-sensitive inward current was noted that corresponded to the h-current. PLCs received both excitatory and inhibitory synaptic inputs. Functional experiments revealed that 76% and 14% of the spontaneous inhibitory postsynaptic currents recorded from the cell bodies of the PLCs were mediated via glycinergic and GABAergic synapses, respectively. PLCs presented strong cerebellin1-like immunoreactivity, but its distribution differed from that seen in cerebellar Purkinje cells. Our results indicate that PLCs are parts of the synaptic circuitry of the CN, thus they may be actively involved in the processing and analysis of auditory information.

  4. Releasing dentate nucleus cells from Purkinje cell inhibition generates output from the cerebrocerebellum.

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    Takahiro Ishikawa

    Full Text Available The cerebellum generates its vast amount of output to the cerebral cortex through the dentate nucleus (DN that is essential for precise limb movements in primates. Nuclear cells in DN generate burst activity prior to limb movement, and inactivation of DN results in cerebellar ataxia. The question is how DN cells become active under intensive inhibitory drive from Purkinje cells (PCs. There are two excitatory inputs to DN, mossy fiber and climbing fiber collaterals, but neither of them appears to have sufficient strength for generation of burst activity in DN. Therefore, we can assume two possible mechanisms: post-inhibitory rebound excitation and disinhibition. If rebound excitation works, phasic excitation of PCs and a concomitant inhibition of DN cells should precede the excitation of DN cells. On the other hand, if disinhibition plays a primary role, phasic suppression of PCs and activation of DN cells should be observed at the same timing. To examine these two hypotheses, we compared the activity patterns of PCs in the cerebrocerebellum and DN cells during step-tracking wrist movements in three Japanese monkeys. As a result, we found that the majority of wrist-movement-related PCs were suppressed prior to movement onset and the majority of wrist-movement-related DN cells showed concurrent burst activity without prior suppression. In a minority of PCs and DN cells, movement-related increases and decreases in activity, respectively, developed later. These activity patterns suggest that the initial burst activity in DN cells is generated by reduced inhibition from PCs, i.e., by disinhibition. Our results indicate that suppression of PCs, which has been considered secondary to facilitation, plays the primary role in generating outputs from DN. Our findings provide a new perspective on the mechanisms used by PCs to influence limb motor control and on the plastic changes that underlie motor learning in the cerebrocerebellum.

  5. Beyond “all-or-nothing” climbing fibers: graded representation of teaching signals in Purkinje cells (United States)

    Najafi, Farzaneh; Medina, Javier F.


    Arguments about the function of the climbing fiber (CF) input to the cerebellar cortex have fueled a rabid debate that started over 40 years ago, and continues to polarize the field to this day. The origin of the controversy can be traced back to 1969, the year David Marr published part of his dissertation work in a paper entitled “A theory of cerebellar cortex.” In Marr’s theory, CFs play a key role during the process of motor learning, providing an instructive signal that serves as a “teacher” for the post-synaptic Purkinje cells. Although this influential idea has found its way into the mainstream, a number of objections have been raised. For example, several investigators have pointed out that the seemingly “all-or-nothing” activation of the CF input provides little information and is too ambiguous to serve as an effective instructive signal. Here, we take a fresh look at these arguments in light of new evidence about the peculiar physiology of CFs. Based on recent findings we propose that at the level of an individual Purkinje cell, a graded instructive signal can be effectively encoded via pre- or post-synaptic modulation of its one and only CF input. PMID:23847473

  6. Persistent posttetanic depression at cerebellar parallel fiber to Purkinje cell synapses.

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    Astrid Bergerot

    Full Text Available Plasticity at the cerebellar parallel fiber to Purkinje cell synapse may underlie information processing and motor learning. In vivo, parallel fibers appear to fire in short high frequency bursts likely to activate sparsely distributed synapses over the Purkinje cell dendritic tree. Here, we report that short parallel fiber tetanic stimulation evokes a ∼7-15% depression which develops over 2 min and lasts for at least 20 min. In contrast to the concomitantly evoked short-term endocannabinoid-mediated depression, this persistent posttetanic depression (PTD does not exhibit a dependency on the spatial pattern of synapse activation and is not caused by any detectable change in presynaptic calcium signaling. This persistent PTD is however associated with increased paired-pulse facilitation and coefficient of variation of synaptic responses, suggesting that its expression is presynaptic. The chelation of postsynaptic calcium prevents its induction, suggesting that post- to presynaptic (retrograde signaling is required. We rule out endocannabinoid signaling since the inhibition of type 1 cannabinoid receptors, monoacylglycerol lipase or vanilloid receptor 1, or incubation with anandamide had no detectable effect. The persistent PTD is maximal in pre-adolescent mice, abolished by adrenergic and dopaminergic receptors block, but unaffected by adrenergic and dopaminergic agonists. Our data unveils a novel form of plasticity at parallel fiber synapses: a persistent PTD induced by physiologically relevant input patterns, age-dependent, and strongly modulated by the monoaminergic system. We further provide evidence supporting that the plasticity mechanism involves retrograde signaling and presynaptic diacylglycerol.

  7. A deficiency of ceramide biosynthesis causes cerebellar purkinje cell neurodegeneration and lipofuscin accumulation.

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    Lihong Zhao


    Full Text Available Sphingolipids, lipids with a common sphingoid base (also termed long chain base backbone, play essential cellular structural and signaling functions. Alterations of sphingolipid levels have been implicated in many diseases, including neurodegenerative disorders. However, it remains largely unclear whether sphingolipid changes in these diseases are pathological events or homeostatic responses. Furthermore, how changes in sphingolipid homeostasis shape the progression of aging and neurodegeneration remains to be clarified. We identified two mouse strains, flincher (fln and toppler (to, with spontaneous recessive mutations that cause cerebellar ataxia and Purkinje cell degeneration. Positional cloning demonstrated that these mutations reside in the Lass1 gene. Lass1 encodes (dihydroceramide synthase 1 (CerS1, which is highly expressed in neurons. Both fln and to mutations caused complete loss of CerS1 catalytic activity, which resulted in a reduction in sphingolipid biosynthesis in the brain and dramatic changes in steady-state levels of sphingolipids and sphingoid bases. In addition to Purkinje cell death, deficiency of CerS1 function also induced accumulation of lipofuscin with ubiquitylated proteins in many brain regions. Our results demonstrate clearly that ceramide biosynthesis deficiency can cause neurodegeneration and suggest a novel mechanism of lipofuscin formation, a common phenomenon that occurs during normal aging and in some neurodegenerative diseases.

  8. Topography of Purkinje cells and other calbindin-immunoreactive cells within adult and hatchling turtle cerebellum. (United States)

    Ariel, Michael; Ward, Kyle C; Tolbert, Daniel L


    The turtle's cerebellum (Cb) is an unfoliated sheet, so the topography of its entire cortex can be easily studied physiologically by optical recordings. However, unlike the mammalian Cb, little is known about the topography of turtle Purkinje cells (PCs). Here, topography was examined using calbindin-D(28K) immunohistochemistry of adult and hatchling turtles (Trachemys scripta elegans, 2.5-15 cm carapace length). Each Cb was flattened between two Sylgard sheets and fixed in paraformaldehyde. Sections (52 microm thick) were cut parallel to the flattened cortex (tangential), resulting in calbindin-immunolabeled PCs being localized to three to six sections for each turtle. PC position and size were quantified using Neurolucida Image Analysis system. Although hatchling Cb were medial-laterally narrower (3.0 vs. 6.5 mm) and rostral-caudally shorter (2.5 vs. 5.5 mm) than adult Cb, both averaged near 15,000 PCs distributed uniformly. Hatchling PCs were smaller than adult PCs (178 vs. 551 microm(2)) and more densely packed (2,180 vs. 625 cells/mm(2)). Calbindin immunoreactivity also labeled non-PCs along the Cb's marginal rim and its caudal pole. Many of these were very small (22.9 microm(2)) ovoid-shaped cells clustered together, possibly proliferating external granule layer cells. Other labeled cells were larger and fusiform-shaped (12.6 x 33.4 microm) adjacent to inner granule cells along the marginal rim, suggestive of migrating cells. It is not known whether these are new neurons being generated within the adult and hatchling Cb and if they connect to efferent and afferent paths. Based on these anatomical findings, we suggest that unique physiological features may exist along the rim of the turtle Cb.

  9. Dose response relationship of disturbed migration of Purkinje cells in the cerebellum due to X-irradiation

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    Darmanto, W.; Inouye, Minoru; Hayasaka, Shizu; Takagishi, Yoshiko; Aolad, H.; Murata, Yoshiharu [Nagoya Univ. (Japan). Research Inst. of Environmental Medicine


    Pregnant rats were exposed to 2.0, 2.25 or 2.5 Gy X-irradiation on gestation day 21. Pups were sacrificed 12 hr after exposure, and on postnatal day 5 (P5), P7 and P9. Their cerebella were observed immunohistochemically using anti-inositol 1,4,5 triphosphate (IP3) receptor antibody to identify Purkinje cells. These cells were disturbed to migrate and remained in the internal granular layer and white matter of the cerebellum. They had short dendrites, and some showed an abnormal direction of dendrites in rats exposed to 2.25 or 2.5 Gy. Alignment of Purkinje cells was also disturbed when examined either on P5, P7 or P9 especially by doses of 2.25 and 2.5 Gy. There was a relationship between X-ray doses and the number of cells piling up in the Purkinje cell layer of the cerebellum. The dose-response relationship with the number of ectopic Purkinje cells was noted in the anterior lobes of the cerebellum. (author)

  10. Increased GAD67 mRNA expression in cerebellar interneurons in autism: implications for Purkinje cell dysfunction. (United States)

    Yip, Jane; Soghomonian, Jean-Jacques; Blatt, Gene J


    It has been widely reported that in autism, the number of Purkinje cells (PCs) is decreased, and recently, decreased expression of glutamic acid decarboxylase 67 (GAD67) mRNA in Purkinje cells also has been observed. However, the autism literature has not addressed key GABAergic inputs into Purkinje cells. Inhibitory basket and stellate cell interneurons in the molecular layer of the cerebellar cortex provide direct key GABAergic input into Purkinje cells and could potently influence the output of Purkinje cells to deep cerebellar nuclei. We investigated the capacity for interneuronal synthesis of gamma-amino butyric acid (GABA) in both types of interneurons that innervate the remaining PCs in the posterolateral cerebellar hemisphere in autism. The level of GAD67 mRNA, one of the isoforms of the key synthesizing enzymes for GABA, was quantified at the single-cell level using in situ hybridization in brains of autistic and aged-matched controls. The National Institutes of Health imaging system showed that expression of GAD67 mRNA in basket cells was significantly up-regulated, by 28%, in eight autistic brains compared with that in eight control brains (mean +/- SEM pixels per cell, 1.03 +/- 0.05 versus 0.69 +/- 0.05, respectively; P levels, but this did not reach significance. The results suggest that basket cells likely provide increased GABAergic feed-forward inhibition to PCs in autism, directly affecting PC output to target neurons in the dentate nucleus and potentially disrupting its modulatory role in key motor and/or cognitive behaviors in autistic individuals.

  11. Ectopic overexpression of engrailed-2 in cerebellar Purkinje cells causes restricted cell loss and retarded external germinal layer development at lobule junctions. (United States)

    Baader, S L; Sanlioglu, S; Berrebi, A S; Parker-Thornburg, J; Oberdick, J


    Members of the En and Wnt gene families seem to play a key role in the early specification of the brain territory that gives rise to the cerebellum, the midhindbrain junction. To analyze the possible continuous role of the En and Wnt signaling pathway in later cerebellar patterning and function, we expressed En-2 ectopically in Purkinje cells during late embryonic and postnatal cerebellar development. As a result of this expression, the cerebellum is greatly reduced in size, and Purkinje cell numbers throughout the cerebellum are reduced by more than one-third relative to normal animals. Detailed analysis of both adult and developing cerebella reveals a pattern of selectivity to the loss of Purkinje cells and other cerebellar neurons. This is observed as a general loss of prominence of cerebellar fissures that is highlighted by a total loss of sublobular fissures. In contrast, mediolateral patterning is generally only subtly affected. That En-2 overexpression selectively affects Purkinje cells in the transition zone between lobules is evidenced by direct observation of selective Purkinje cell loss in certain fissures and by the observation that growth and migration of the external germinal layer (EGL) is selectively retarded in the deep fissures during early postnatal development. Thus, in addition to demonstrating the critical role of Purkinje cells in the generation and migration of granule cells, the heterogeneous distribution of cellular effects induced by ectopic En expression suggests a relatively late morphogenetic role for this and other segment polarity proteins, mainly oriented at lobule junctions.

  12. Prophylactic role of melatonin against radiation induced damage in mouse cerebellum with special reference to Purkinje cells

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    Sisodia, Rashmi; Kumari, Seema; Verma, Rajesh Kumar; Bhatia, A L [Neurobiology Laboratory, Department of Zoology, University of Rajasthan, Jaipur 302004 (India)


    Melatonin, a hormone with a proven antioxidative efficacy, crosses all morphophysiological barriers, including the blood-brain barrier, and distributes throughout the cell. The present study is an attempt to investigate the prophylactic influence of a chronic low level of melatonin against an acute radiation induced oxidative stress in the cerebellum of Swiss albino mice, with special reference to Purkinje cells. After 15 days of treatment the mice were sacrificed at various intervals from 1 to 30 days. Biochemical parameters included lipid peroxidation (LPO) and glutathione (GSH) levels as the endpoints. The quantitative study included alterations in number and volume of Purkinje cells. Swiss albino mice were orally administered a very low dose of melatonin (0.25 mg/mouse/day) for 15 consecutive days before single exposure to 4 Gy gamma radiation. Melatonin checked the augmented levels of LPO, by approximately 55%, by day 30 day post-exposure. Radiation induced depleted levels of GSH could be raised by 68.9% by day 30 post-exposure. Radiation exposure resulted in a reduction of the volume of Purkinje cells and their total number. The administration of melatonin significantly protected against the radiation induced decreases in Purkinje cell volume and number. Results indicate the antioxidative properties of melatonin resulting in its prophylactic property against radiation induced biochemical and cellular alterations in the cerebellum. The findings support the idea that melatonin may be used as an anti-irradiation drug due to its potent free radical scavenging and antioxidative efficacy.

  13. Kv3.3 channels at the Purkinje cell soma are necessary for generation of the classical complex spike waveform. (United States)

    Zagha, Edward; Lang, Eric J; Rudy, Bernardo


    Voltage-gated potassium channel subunit Kv3.3 is prominently expressed in cerebellar Purkinje cells and is known to be important for cerebellar function, as human and mouse movement disorders result from mutations in Kv3.3. To understand these behavioral deficits, it is necessary to know the role of Kv3.3 channels on the physiological responses of Purkinje cells. We studied the function of Kv3.3 channels in regulating the synaptically evoked Purkinje cell complex spike, the massive postsynaptic response to the activation of climbing fiber afferents, believed to be fundamental to cerebellar physiology. Acute slice recordings revealed that Kv3.3 channels are required for generation of the repetitive spikelets of the complex spike. We found that spikelet expression is regulated by somatic, and not by dendritic, Kv3 activity, which is consistent with dual somatic-dendritic recordings that demonstrate spikelet generation at axosomatic membranes. Simulations of Purkinje cell Na+ currents show that the unique electrical properties of Kv3 and resurgent Na+ channels are coordinated to limit accumulation of Na+ channel inactivation and enable rapid, repetitive firing. We additionally show that Kv3.3 knock-out mice produce altered complex spikes in vitro and in vivo, which is likely a cellular substrate of the cerebellar phenotypes observed in these mice. This characterization presents new tools to study complex spike function, cerebellar signaling, and Kv3.3-dependent human and mouse phenotypes.

  14. High dosage of monosodium glutamate causes deficits of the motor coordination and the number of cerebellar Purkinje cells of rats. (United States)

    Prastiwi, D; Djunaidi, A; Partadiredja, G


    Monosodium glutamate (MSG) has been widely used throughout the world as a flavoring agent of food. However, MSG at certain dosages is also thought to cause damage to many organs, including cerebellum. This study aimed at investigating the effects of different doses of MSG on the motor coordination and the number of Purkinje cells of the cerebellum of Wistar rats. A total of 24 male rats aged 4 to 5 weeks were divided into four groups, namely, control (C), T2.5, T3, and T3.5 groups, which received intraperitoneal injection of 0.9% sodium chloride solution, 2.5 mg/g body weight (bw) of MSG, 3.0 mg/g bw of MSG, and 3.5 mg/g bw of MSG, respectively, for 10 consecutive days. The motor coordination of the rats was examined prior and subsequent to the treatment. The number of cerebellar Purkinje cells was estimated using physical fractionator method. It has been found that the administration of MSG at a dosage of 3.5 mg/g bw, but not at lower dosages, caused a significant decrease of motor coordination and the estimated total number of Purkinje cells of rats. There was also a significant correlation between motor coordination and the total number of Purkinje cells.

  15. Early hypergravity exposure effects calbindin-D28k and inositol-3-phosphate expression in Purkinje cells

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    Bouet, [No Value; Dijk, F; Ijkema-Paassen, J; Wubbels, RJ; van der Want, JJ; Gramsbergen, A


    In this study the effects of hypergravity were analyzed on cerebellar Purkinje cells during early development in rats. The cerebellum is a key structure in the control and the adaptation of posture and anti-gravity activities. This holds particularly when external conditions are modified. Three grou

  16. In Vivo Detection of Reduced Purkinje Cell Fibers with Diffusion MRI Tractography in Children with Autistic Spectrum Disorders

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    Jeong-Won eJeong


    Full Text Available Postmortem neuropathology studies report reduced number and size of Purkinje cells (PC in a majority of cerebellum specimens from persons with autism spectrum disorders (ASD. In this study using diffusion weighted MRI, we investigated whether structural changes related to decreased number and size of PC could be detected in vivo by measuring streamlines connecting the posterior-lateral region of the cerebellar cortex to the dentate nucleus using an independent component analysis with a ball and stick model (ICA+BSM. The tractography was performed in 14 typically developing children (TD and 15 children with ASD, using a cerebellar cortex seed region (crus I and II and two sorting regions, the dorsal dentate nucleus (DDN and the ventral dentate nucleus (VDN. Decreased numbers of streamlines were found in the children with ASD in the pathway connecting cerebellar cortex to right VDN (p-value = 0.015. Reduced fractional anisotropy values were observed in pathways connecting the cerebellar cortex to the right DDN (p-value=0.008, the right VDN (p-value=0.010 and left VDN (p-value=0.020 in children with ASD compared to the TD group. In an analysis of single subjects, reduced FA in the pathway connecting cerebellar cortex to the right VDN was found in 73% of the children in the ASD group using a threshold of 3 standards errors of the TD group. The detection of diffusion changes in cerebellum may provide an in vivo biomarker of Purkinje cell pathology in children with ASD.

  17. A new Purkinje cell antibody (anti-Ca associated with subacute cerebellar ataxia: immunological characterization

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    Horn Sigrun


    Full Text Available Abstract We report on a newly discovered serum and cerebrospinal fluid (CSF reactivity to Purkinje cells (PCs associated with subacute inflammatory cerebellar ataxia. The patient, a previously healthy 33-year-old lady, presented with severe limb and gait ataxia, dysarthria, and diplopia two weeks after she had recovered from a common cold. Immunohistochemical studies on mouse, rat, and monkey brain sections revealed binding of a high-titer (up to 1:10,000 IgG antibody to the cerebellar molecular layer, Purkinje cell (PC layer, and white matter. The antibody is highly specific for PCs and binds to the cytoplasm as well as to the inner side of the membrane of PC somata, dendrites and axons. It is produced by B cell clones within the CNS, belongs to the IgG1 subclass, and activates complement in vitro. Western blotting of primate cerebellum extract revealed binding of CSF and serum IgG to an 80-97 kDa protein. Extensive control studies were performed to rule out a broad panel of previously described paraneoplastic and non-paraneoplastic antibodies known to be associated with cerebellar ataxia. Screening of >9000 human full length proteins by means of a protein array and additional confirmatory experiments revealed Rho GTPase activating protein 26 (ARHGAP26, GRAF, oligophrenin-1-like protein as the target antigen. Preadsorption of the patient's serum with human ARHGAP26 but not preadsorption with other proteins resulted in complete loss of PC staining. Our findings suggest a role of autoimmunity against ARHGAP26 in the pathogenesis of subacute inflammatory cerebellar ataxia, and extend the panel of diagnostic markers for this devastating disease.

  18. Sensory-Driven Enhancement of Calcium Signals in Individual Purkinje Cell Dendrites of Awake Mice

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    Farzaneh Najafi


    Full Text Available Climbing fibers (CFs are thought to contribute to cerebellar plasticity and learning by triggering a large influx of dendritic calcium in the postsynaptic Purkinje cell (PC to signal the occurrence of an unexpected sensory event. However, CFs fire about once per second whether or not an event occurs, raising the question of how sensory-driven signals might be distinguished from a background of ongoing spontaneous activity. Here, we report that in PC dendrites of awake mice, CF-triggered calcium signals are enhanced when the trigger is a sensory event. In addition, we show that a large fraction of the total enhancement in each PC dendrite can be accounted for by an additional boost of calcium provided by sensory activation of a non-CF input. We suggest that sensory stimulation may modulate dendritic voltage and calcium concentration in PCs to increase the strength of plasticity signals during cerebellar learning.

  19. Multiple subclasses of Purkinje cells in the primate floccular complex provide similar signals to guide learning in the vestibulo-ocular reflex (United States)

    Raymond, J. L.; Lisberger, S. G.


    The neural "learning rules" governing the induction of plasticity in the cerebellum were analyzed by recording the patterns of neural activity in awake, behaving animals during stimuli that induce a form of cerebellum-dependent learning. We recorded the simple- and complex-spike responses of a broad sample of Purkinje cells in the floccular complex during a number of stimulus conditions that induce motor learning in the vestibulo-ocular reflex (VOR). Each subclass of Purkinje cells carried essentially the same information about required changes in the gain of the VOR. The correlation of simple-spike activity in Purkinje cells with activity in vestibular pathways could guide learning during low-frequency but not high-frequency stimuli. Climbing fiber activity could guide learning during all stimuli tested but only if compared with the activity present approximately 100 msec earlier in either vestibular pathways or Purkinje cells.

  20. Signals and Circuits in the Purkinje Neuron

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    Ze'ev R Abrams


    Full Text Available Purkinje neurons in the cerebellum have over 100,000 inputs organized in an orthogonal geometry, and a single output channel. As the sole output of the cerebellar cortex layer, their complex firing pattern has been associated with motor control and learning. As such they have been extensively modeled and measured using tools ranging from electrophysiology and neuroanatomy, to dynamic systems and artificial intelligence methods. However, there is an alternative approach to analyze and describe the neuronal output of these cells using concepts from Electrical Engineering, particularly signal processing and digital/analog circuits. By viewing the Purkinje neuron as an unknown circuit to be reverse-engineered, we can use the tools that provide the foundations of today’s integrated circuits and communication systems to analyze the Purkinje system at the circuit level. We use Fourier transforms to analyze and isolate the inherent frequency modes in the Purkinje neuron and define 3 unique frequency ranges associated with the cells’ output. Comparing the Purkinje neuron to a signal generator that can be externally modulated adds an entire level of complexity to the functional role of these neurons both in terms of data analysis and information processing, relying on Fourier analysis methods in place of statistical ones. We also re-describe some of the recent literature in the field, using the nomenclature of signal processing. Furthermore, by comparing the experimental data of the past decade with basic electronic circuitry, we can resolve the outstanding controversy in the field, by recognizing that the Purkinje neuron can act as a multivibrator circuit.

  1. Cbln1 regulates rapid formation and maintenance of excitatory synapses in mature cerebellar Purkinje cells in vitro and in vivo. (United States)

    Ito-Ishida, Aya; Miura, Eriko; Emi, Kyoichi; Matsuda, Keiko; Iijima, Takatoshi; Kondo, Tetsuro; Kohda, Kazuhisa; Watanabe, Masahiko; Yuzaki, Michisuke


    Although many synapse-organizing molecules have been identified in vitro, their functions in mature neurons in vivo have been mostly unexplored. Cbln1, which belongs to the C1q/tumor necrosis factor superfamily, is the most recently identified protein involved in synapse formation in the mammalian CNS. In the cerebellum, Cbln1 is predominantly produced and secreted from granule cells; cbln1-null mice show ataxia and a severe reduction in the number of synapses between Purkinje cells and parallel fibers (PFs), the axon bundle of granule cells. Here, we show that application of recombinant Cbln1 specifically and reversibly induced PF synapse formation in dissociated cbln1-null Purkinje cells in culture. Cbln1 also rapidly induced electrophysiologically functional and ultrastructurally normal PF synapses in acutely prepared cbln1-null cerebellar slices. Furthermore, a single injection of recombinant Cbln1 rescued severe ataxia in adult cbln1-null mice in vivo by completely, but transiently, restoring PF synapses. Therefore, Cbln1 is a unique synapse organizer that is required not only for the normal development of PF-Purkinje cell synapses but also for their maintenance in the mature cerebellum both in vitro and in vivo. Furthermore, our results indicate that Cbln1 can also rapidly organize new synapses in adult cerebellum, implying its therapeutic potential for cerebellar ataxic disorders.


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    Peter E. Ekanem


    Full Text Available Introduction: Datura stramonium (DS is a tropical ubiquitous shrub which is often used to increase intoxication in some beverages and is also freely used as a hallucinogen. It is a depressant of the central nervous system, yet commonly smoked in like manner tobacco. The present study investigated changes induced by intoxication with DS on the purkinje cells and parallel fibres of the cerebellum in Wistar rats to further elucidate the effects of this drug on cerebellar structure. Materials and Methods: The study was conducted on both male and female Wistar rats (200-250 g. They were placed into three batches and four groups were derived from each batch, with eight animals per group. Ethanolic dried seed extract of DS was diluted in normal saline and administered intraperitoneally (I.P. at a dose of 750mg/kg and given to the treatment groups: once in batch 1, twice in batch 2, twelve hourly and thrice in batch 3, eight hourly per day respectively for 4 weeks, while the control groups received an equivalent of normal saline. The rats were euthanized and sections of the cerebellum were histologically processed in all groups. Silver impregnation stain for degenerating axons and neurons was used to elucidate the actions of DS on purkinje cells and the parallel fibres of the cerebellum. Results: The result of IP administration of DS extract (750 mg/kg given three times daily to the treated rats showed significant histological changes, which included atrophy of the parallel fibres but no significant changes in the purkinje cells of the cerebellum. Conclusions: Intoxication of DS seed as a result of excessive ingestion may have a selective degenerative effect on the parallel fibres of the granule cells of the cerebellum while the purkinje cells are spared; the implication being motor dysfunction.

  3. Dendritic Kv3.3 potassium channels in cerebellar purkinje cells regulate generation and spatial dynamics of dendritic Ca2+ spikes. (United States)

    Zagha, Edward; Manita, Satoshi; Ross, William N; Rudy, Bernardo


    Purkinje cell dendrites are excitable structures with intrinsic and synaptic conductances contributing to the generation and propagation of electrical activity. Voltage-gated potassium channel subunit Kv3.3 is expressed in the distal dendrites of Purkinje cells. However, the functional relevance of this dendritic distribution is not understood. Moreover, mutations in Kv3.3 cause movement disorders in mice and cerebellar atrophy and ataxia in humans, emphasizing the importance of understanding the role of these channels. In this study, we explore functional implications of this dendritic channel expression and compare Purkinje cell dendritic excitability in wild-type and Kv3.3 knockout mice. We demonstrate enhanced excitability of Purkinje cell dendrites in Kv3.3 knockout mice, despite normal resting membrane properties. Combined data from local application pharmacology, voltage clamp analysis of ionic currents, and assessment of dendritic Ca(2+) spike threshold in Purkinje cells suggest a role for Kv3.3 channels in opposing Ca(2+) spike initiation. To study the physiological relevance of altered dendritic excitability, we measured [Ca(2+)](i) changes throughout the dendritic tree in response to climbing fiber activation. Ca(2+) signals were specifically enhanced in distal dendrites of Kv3.3 knockout Purkinje cells, suggesting a role for dendritic Kv3.3 channels in regulating propagation of electrical activity and Ca(2+) influx in distal dendrites. These findings characterize unique roles of Kv3.3 channels in dendrites, with implications for synaptic integration, plasticity, and human disease.

  4. Bergmann glia and the recognition molecule CHL1 organize GABAergic axons and direct innervation of Purkinje cell dendrites.

    Directory of Open Access Journals (Sweden)

    Fabrice Ango


    Full Text Available The geometric and subcellular organization of axon arbors distributes and regulates electrical signaling in neurons and networks, but the underlying mechanisms have remained elusive. In rodent cerebellar cortex, stellate interneurons elaborate characteristic axon arbors that selectively innervate Purkinje cell dendrites and likely regulate dendritic integration. We used GFP BAC transgenic reporter mice to examine the cellular processes and molecular mechanisms underlying the development of stellate cell axons and their innervation pattern. We show that stellate axons are organized and guided towards Purkinje cell dendrites by an intermediate scaffold of Bergmann glial (BG fibers. The L1 family immunoglobulin protein Close Homologue of L1 (CHL1 is localized to apical BG fibers and stellate cells during the development of stellate axon arbors. In the absence of CHL1, stellate axons deviate from BG fibers and show aberrant branching and orientation. Furthermore, synapse formation between aberrant stellate axons and Purkinje dendrites is reduced and cannot be maintained, leading to progressive atrophy of axon terminals. These results establish BG fibers as a guiding scaffold and CHL1 a molecular signal in the organization of stellate axon arbors and in directing their dendritic innervation.

  5. Curcumin alters motor coordination but not total number of Purkinje cells in the cerebellum of adolescent male Wistar rats

    Institute of Scientific and Technical Information of China (English)

    Ginus Partadiredja; Sutarman; Taufik Nur Yahya; Christiana Tri Nuryana; Rina Susilowati


    OBJECTIVE:The present study aimed at investigating the effects of curcumin on the motor coordination and the estimate of the total number of cerebellar Purkinje cells of adolescent Wistar rats exposed to ethanol.METHODS:The total of 21 male Wistar rats aged 37 d old were divided into three groups,namely ethanol,ethanol-curcumin,and control groups.The ethanol group received 1.5 g/kg ethanol injected intraperitoneally and water given per oral; the ethanol-curcumin group received 1.5 g/kg ethanol injected intraperitoneally and curcumin extract given per oral; the control group received saline injection and oral water.The treatment was carried out daily for one month,after which the motor coordination performance of the rats was examined using revolving drum apparatus at test days 1,8,and 15.The rats were finally sacrificed and the cerebellum of the rats was further processed for stereological analysis.The estimate of the total number of Purkinje cells was calculated using physical fractionator method.RESULTS:The ethanol-curcumin group performed better than both ethanol and control groups in the motor coordination ability at day 8 of testing (P< 0.01).No Purkinje cell loss was observed as a result of one month intraperitoneal injection of ethanol.CONCLUSION:Curcumin may exert beneficial effects on the motor coordination of adolescent rats exposed to ethanol via undetermined hormetic mechanisms.

  6. The sorting receptor Rer1 controls Purkinje cell function via voltage gated sodium channels (United States)

    Valkova, Christina; Liebmann, Lutz; Krämer, Andreas; Hübner, Christian A.; Kaether, Christoph


    Rer1 is a sorting receptor in the early secretory pathway that controls the assembly and the cell surface transport of selected multimeric membrane protein complexes. Mice with a Purkinje cell (PC) specific deletion of Rer1 showed normal polarization and differentiation of PCs and normal development of the cerebellum. However, PC-specific loss of Rer1 led to age-dependent motor deficits in beam walk, ladder climbing and gait. Analysis of brain sections revealed a specific degeneration of PCs in the anterior cerebellar lobe in old animals. Electrophysiological recordings demonstrated severe deficits in spontaneous action potential generation. Measurements of resurgent currents indicated decreased surface densities of voltage-gated sodium channels (Nav), but not changes in individual channels. Analysis of mice with a whole brain Rer1-deletion demonstrated a strong down-regulation of Nav1.6 and 1.1 in the absence of Rer1, whereas protein levels of the related Cav2.1 and of Kv3.3 and 7.2 channels were not affected. The data suggest that Rer1 controls the assembly and transport of Nav1.1 and 1.6, the principal sodium channels responsible for recurrent firing, in PCs. PMID:28117367

  7. Comparative morphology of dendritic arbors in populations of Purkinje cells in mouse sulcus and apex. (United States)

    Nedelescu, Hermina; Abdelhack, Mohamed


    Foliation divides the mammalian cerebellum into structurally distinct subdivisions, including the concave sulcus and the convex apex. Purkinje cell (PC) dendritic morphology varies between subdivisions and changes significantly ontogenetically. Since dendritic morphology both enables and limits sensory-motor circuit function, it is important to understand how neuronal architectures differ between brain regions. This study employed quantitative confocal microcopy to reconstruct dendritic arbors of cerebellar PCs expressing green fluorescent protein and compared arbor morphology between PCs of sulcus and apex in young and old mice. Arbors were digitized from high z-resolution (0.25 µm) image stacks using an adaptation of Neurolucida's (MBF Bioscience) continuous contour tracing tool, designed for drawing neuronal somata. Reconstructed morphologies reveal that dendritic arbors of sulcus and apex exhibit profound differences. In sulcus, 72% of the young PC population possesses two primary dendrites, whereas in apex, only 28% do. Spatial constraints in the young sulcus cause significantly more dendritic arbor overlap than in young apex, a distinction that disappears in adulthood. However, adult sulcus PC arbors develop a greater number of branch crossings. These results suggest developmental neuronal plasticity that enables cerebellar PCs to attain correct functional adult architecture under different spatial constraints.

  8. Purkinje cell cytoplasmic antibody type 1 (anti-Yo) autoimmunity in a child with Down syndrome. (United States)

    Philipps, Guillermo; Alisanski, Susan B; Pranzatelli, Michael; Clardy, Stacey L; Lennon, Vanda A; McKeon, Andrew


    Purkinje cell cytoplasmic antibody type 1 (PCA-1)-IgG (or anti-Yo) is characteristically detected in women with gynecological or breast adenocarcinoma. We describe 2 unique scenarios occurring in 1 patient: PCA-1 paraneoplastic autoimmunity in a child, and a paraneoplastic neurological disorder in the context of Down syndrome. A child with Down syndrome and a history of adrenocortical carcinoma resected at age 1 year presented at age 7 years with cerebellar ataxia of subacute onset. Paraneoplastic serological and cerebrospinal fluid evaluations revealed PCA-1. Serological and biochemical studies also supported a diagnosis of subclinical autoimmune hypothyroidism. Extensive serum, urine, and radiological testing did not reveal a new or recurrent neoplasm. Neurological improvements after standard immunotherapy were lacking. Solid organ neoplasms are uncommon among patients with Down syndrome, but organ-specific autoimmune diseases are common. In our patient, Down syndrome-related impaired T regulatory lymphocyte function (previously reported) may have resulted in both enhanced immunity against an undetected solid neoplasm and paraneoplastic neurological (PCA-1) autoimmunity.

  9. Oxygen-glucose deprivation increases firing of unipolar brush cells and enhances spontaneous EPSCs in Purkinje cells in the vestibulo-cerebellum. (United States)

    Takayasu, Yukihiro; Shino, Masato; Nikkuni, Osamu; Yoshida, Yukari; Furuya, Nobuhiko; Chikamatsu, Kazuaki


    Unipolar brush cells (UBCs) are excitatory interneurons in the granular layer of the cerebellar cortex, which are predominantly distributed in the vestibulo-cerebellar region. The unique firing properties and synaptic connections of UBCs may underlie lobular heterogeneity of excitability in the granular layer and the susceptibility to ischemia-induced excitotoxicity. In this study, we investigated the effects of oxygen-glucose deprivation (OGD) on the firing properties of UBCs and granule cells and spontaneous excitatory postsynaptic currents (sEPSCs) of Purkinje cells using whole-cell recordings. Short-term OGD induced increases in spontaneous firing of UBCs by causing membrane depolarization via the activation of NMDA receptors. UBC firing indirectly affected Purkinje cells by altering parallel fiber inputs of a subset granule cells, resulting in a marked increase in sEPSCs in Purkinje cells in vestibulo-cerebellar lobules IX-X, but not in lobules IV-VI, which have fewer UBCs. Similarly, the frequency and amplitude of sEPSCs in Purkinje cells were significantly greater in lobules IX-X than in IV-VI, even in control conditions. These results reveal that UBCs play key roles in regulating local excitability in the granular layer, resulting in lobular heterogeneity in the susceptibility to ischemic insult in the cerebellum.

  10. Modulation of Purkinje cell complex spike waveform by synchrony levels in the olivocerebellar system. (United States)

    Lang, Eric J; Tang, Tianyu; Suh, Colleen Y; Xiao, Jianqiang; Kotsurovskyy, Yuriy; Blenkinsop, Timothy A; Marshall, Sarah P; Sugihara, Izumi


    Purkinje cells (PCs) generate complex spikes (CSs) when activated by the olivocerebellar system. Unlike most spikes, the CS waveform is highly variable, with the number, amplitude, and timing of the spikelets that comprise it varying with each occurrence. This variability suggests that CS waveform could be an important control parameter of olivocerebellar activity. The origin of this variation is not well known. Thus, we obtained extracellular recordings of CSs to investigate the possibility that the electrical coupling state of the inferior olive (IO) affects the CS waveform. Using multielectrode recordings from arrays of PCs we showed that the variance in the recording signal during the period when the spikelets occur is correlated with CS synchrony levels in local groups of PCs. The correlation was demonstrated under both ketamine and urethane, indicating that it is robust. Moreover, climbing fiber reflex evoked CSs showed an analogous positive correlation between spikelet-related variance and the number of cells that responded to a stimulus. Intra-IO injections of GABA-A receptor antagonists or the gap junction blocker carbenoxolone produced correlated changes in the variance and synchrony levels, indicating the presence of a causal relationship. Control experiments showed that changes in variance with synchrony were primarily due to changes in the CS waveform, as opposed to changes in the strength of field potentials from surrounding cells. Direct counts of spikelets showed that their number increased with synchronization of CS activity. In sum, these results provide evidence of a causal link between two of the distinguishing characteristics of the olivocerebellar system, its ability to generate synchronous activity and the waveform of the CS.

  11. Nucleolar disruption and cajal body disassembly are nuclear hallmarks of DNA damage-induced neurodegeneration in purkinje cells. (United States)

    Baltanás, Fernando C; Casafont, Iñigo; Weruaga, Eduardo; Alonso, José R; Berciano, María T; Lafarga, Miguel


    The Purkinje cell (PC) degeneration (pcd) phenotype results from mutation in nna1 gene and is associated with the degeneration and death of PCs during the postnatal life. Although the pcd mutation is a model of the ataxic mouse, it shares clinical and pathological characteristics of inherited human spinocerebellar ataxias. PC degeneration in pcd mice provides a useful neuronal system to study nuclear mechanisms involved in DNA damage-dependent neurodegeneration, particularly the contribution of nucleoli and Cajal bodies (CBs). Both nuclear structures are engaged in housekeeping functions for neuronal survival, the biogenesis of ribosomes and the maturation of snRNPs and snoRNPs required for pre-mRNA and pre-rRNA processing, respectively. In this study, we use ultrastructural analysis, in situ transcription assay and molecular markers for DNA damage, nucleoli and CB components to demonstrate that PC degeneration involves the progressive accumulation of nuclear DNA damage associated with disruption of nucleoli and CBs, disassembly of polyribosomes into monoribosomes, ribophagy and shut down of nucleolar and extranucleolar transcription. Microarray analysis reveals that four genes encoding repressors of nucleolar rRNA synthesis (p53, Rb, PTEN and SNF2) are upregulated in the cerebellum of pcd mice. Collectively, these data support that nucleolar and CB alterations are hallmarks of DNA damage-induced neurodegeneration.

  12. Differential GABAergic and glycinergic inputs of inhibitory interneurons and Purkinje cells to principal cells of the cerebellar nuclei. (United States)

    Husson, Zoé; Rousseau, Charly V; Broll, Ilja; Zeilhofer, Hanns Ulrich; Dieudonné, Stéphane


    The principal neurons of the cerebellar nuclei (CN), the sole output of the olivo-cerebellar system, receive a massive inhibitory input from Purkinje cells (PCs) of the cerebellar cortex. Morphological evidence suggests that CN principal cells are also contacted by inhibitory interneurons, but the properties of this connection are unknown. Using transgenic, tracing, and immunohistochemical approaches in mice, we show that CN interneurons form a large heterogeneous population with GABA/glycinergic phenotypes, distinct from GABAergic olive-projecting neurons. CN interneurons are found to contact principal output neurons, via glycine receptor (GlyR)-enriched synapses, virtually devoid of the main GABA receptor (GABAR) subunits α1 and γ2. Those clusters account for 5% of the total number of inhibitory receptor clusters on principal neurons. Brief optogenetic stimulations of CN interneurons, through selective expression of channelrhodopsin 2 after viral-mediated transfection of the flexed gene in GlyT2-Cre transgenic mice, evoked fast IPSCs in principal cells. GlyR activation accounted for 15% of interneuron IPSC amplitude, while the remaining current was mediated by activation of GABAR. Surprisingly, small GlyR clusters were also found at PC synapses onto principal CN neurons in addition to α1 and γ2 GABAR subunits. However, GlyR activation was found to account for <3% of the PC inhibitory synaptic currents evoked by electrical stimulation. This work establishes CN glycinergic neurons as a significant source of inhibition to CN principal cells, forming contacts molecularly distinct from, but functionally similar to, Purkinje cell synapses. Their impact on CN output, motor learning, and motor execution deserves further investigation.

  13. Intracellular correlates of acquisition and long-term memory of classical conditioning in Purkinje cell dendrites in slices of rabbit cerebellar lobule HVI. (United States)

    Schreurs, B G; Gusev, P A; Tomsic, D; Alkon, D L; Shi, T


    Intradendritic recordings in Purkinje cells from a defined area in parasaggital slices of cerebellar lobule HVI, obtained after rabbits were given either paired (classical conditioning) or explicitly unpaired (control) presentations of tone and periorbital electrical stimulation, were used to assess the nature and duration of conditioning-specific changes in Purkinje cell dendritic membrane excitability. We found a strong relationship between the level of conditioning and Purkinje cell dendritic membrane excitability after initial acquisition of the conditioned response. Moreover, conditioning-specific increases in Purkinje cell excitability were still present 1 month after classical conditioning. Although dendritically recorded membrane potential, input resistance, and amplitude of somatic and dendritic spikes were not different in cells from paired or control animals, the size of a potassium channel-mediated transient hyperpolarization was significantly smaller in cells from animals that received classical conditioning. In slices of lobule HVI obtained from naive rabbits, the conditioning-related increases in membrane excitability could be mimicked by application of potassium channel antagonist tetraethylammonium chloride, iberiotoxin, or 4-aminopyridine. However, only 4-aminopyridine was able to reduce the transient hyperpolarization. The pharmacological data suggest a role for potassium channels and, possibly, channels mediating an IA-like current, in learning-specific changes in membrane excitability. The conditioning-specific increase in Purkinje cell dendritic excitability produces an afterhyperpolarization, which is hypothesized to release the cerebellar deep nuclei from inhibition, allowing conditioned responses to be elicited via the red nucleus and accessory abducens motorneurons.

  14. Ethanol Modulates the Spontaneous Complex Spike Waveform of Cerebellar Purkinje Cells Recorded in vivo in Mice (United States)

    Zhang, Guang-Jian; Wu, Mao-Cheng; Shi, Jin-Di; Xu, Yin-Hua; Chu, Chun-Ping; Cui, Song-Biao; Qiu, De-Lai


    Cerebellar Purkinje cells (PCs) are sensitive to ethanol, but the effect of ethanol on spontaneous complex spike (CS) activity in these cells in vivo is currently unknown. Here, we investigated the effect of ethanol on spontaneous CS activity in PCs in urethane-anesthetized mice using in vivo patch-clamp recordings and pharmacological manipulation. Ethanol (300 mM) induced a decrease in the CS-evoked pause in simple spike (SS) firing and in the amplitude of the afterhyperpolarization (AHP) under current clamp conditions. Under voltage-clamp conditions, ethanol significantly decreased the area under the curve (AUC) and the number of CS spikelets, without changing the spontaneous frequency of the CSs or the instantaneous frequency of the CS spikelets. Ethanol-induced a decrease in the AUC of spontaneous CSs was concentration dependent. The EC50 of ethanol for decreasing the AUC of spontaneous CSs was 168.5 mM. Blocking N-methyl-D-aspartate receptors (NMDARs) failed to prevent the ethanol-induced decreases in the CS waveform parameters. However, blockade of cannabinoid receptor 1 (CB1) significantly suppressed the ethanol-induced effects on the CS-evoked pause in SS firing, amplitude of the AHP, spikelet number and the AUC of CSs. Moreover, a CB1 receptor agonist not only reduced the number of spikelets and the AUC of CSs, but also prevented the ethanol-induced inhibition of CS activity. Our results indicate that ethanol inhibits CS activity via activation of the CB1 receptor in vivo in mice, suggesting that excessive ethanol intake inhibits climbing fiber (CF)–PC synaptic transmission by modulating CB1 receptors in the cerebellar cortex. PMID:28293172

  15. Larger rate dependence of late sodium current in cardiac Purkinje cells: A potential link to arrhythmogenesis. (United States)

    Li, Wei; Yu, Ying; Hou, Jian-Wen; Zhou, Zhi-Wen; Guo, Kai; Zhang, Peng-Pai; Wang, Zhi-Quan; Yan, Jian-Hua; Sun, Jian; Zhou, Qing; Wang, Yue-Peng; Li, Yi-Gang


    Purkinje cells (PCs) have a steeper rate dependence of repolarization and are more susceptible to arrhythmic activity than do ventricular myocytes (VMs). Late sodium current (INaL) is rate dependent and contributes to rate dependence of repolarization. This study sought to test our hypothesis that PCs have a larger rate dependence of INaL, contributing to their steeper rate dependence of repolarization and higher susceptibility to arrhythmic activity, than do VMs. INaL was recorded in isolated rabbit PCs and VMs with the whole-cell patch clamp technique. Action potential was examined using the microelectrode technique. Compared with VMs, PCs exhibited a significantly larger rate dependence of INaL with a larger INaL to basic cycle length (BCL) slope. Moreover, PCs had a larger rate dependence of INaL decay and slower recovery kinetics. Interestingly, the larger rate dependence of INaL matched to a steeper rate dependence of action potential duration (APD) in PCs. The INaL blocker tetrodotoxin significantly blunted, while the INaL enhancer anemone toxin (ATX-II) significantly increased, the rate dependence of INaL and APD in PCs and VMs. In the presence of ATX-II, the rate dependence of INaL in PCs was markedly larger than that in VMs, causing a much steeper rate dependence of APD in PCs. Accordingly, PCs exhibited greater rate-dependent electrical instability and were more prone to ATX-II-induced early afterdepolarizations, which were completely inhibited by the INaL inhibitor ranolazine. PCs have a significantly larger rate dependence of INaL than do VMs because of distinctive INaL decay and recovery kinetics, which contributes to their larger rate adaptation, and simultaneously predisposes them to a higher risk of arrhythmogenesis. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  16. Inositol Hexakisphosphate Kinase-3 Regulates the Morphology and Synapse Formation of Cerebellar Purkinje Cells via Spectrin/Adducin


    Fu, Chenglai; Xu, Jing; Li, Ruo-Jing; Crawford, Joshua A.; Khan, A. Basit; Ma, Ting Martin; Cha, Jiyoung Y.; Snowman, Adele M.; Pletnikov, Mikhail V.; Snyder, Solomon H.


    The inositol hexakisphosphate kinases (IP6Ks) are the principal enzymes that generate inositol pyrophosphates. There are three IP6Ks (IP6K1, 2, and 3). Functions of IP6K1 and IP6K2 have been substantially delineated, but little is known of IP6K3's role in normal physiology, especially in the brain. To elucidate functions of IP6K3, we generated mice with targeted deletion of IP6K3. We demonstrate that IP6K3 is highly concentrated in the brain in cerebellar Purkinje cells. IP6K3 physiologically...

  17. Embryonic origins of ZebrinII parasagittal stripes and establishment of topographic Purkinje cell projections. (United States)

    Sillitoe, R V; Gopal, N; Joyner, A L


    The establishment of neural circuits involves both the precise positioning of cells within brain regions and projection of axons to specific target cells. In the cerebellum (Cb), the medial-lateral (M-L) and anterior-posterior (A-P) position of each Purkinje cell (PC) and the topography of its axon can be defined with respect to two coordinate systems within the Cb; one based on the pattern of lobules and the other on PC gene expression in parasagittal clusters in the embryo (e.g. Pcp2) and stripes in the adult (e.g. ZebrinII). The relationship between the embryonic clusters of molecularly defined PCs and particular adult PC stripes is not clear. Using a mouse genetic inducible fate mapping (GIFM) approach and a Pcp2-CreER-IRES-hAP transgene, we marked three bilateral clusters of PC clusters with myristolated green fluorescent protein (mGfp) on approximately embryonic day (E) 15 and followed their fate into adulthood. We found that these three clusters contributed specifically to ZebrinII-expressing PCs, including nine of the adult stripes. This result suggests that embryonic PCs maintain a particular molecular identity, and that each embryonic cluster can contribute PCs to more than one adult M-L stripe. Each PC projects a primary axon to one of the deep cerebellar nuclei (DCN) or the vestibular nuclei in the brainstem in an organized fashion that relates to the position of the PCs along the M-L axis. We characterized when PC axons from the three M-L clusters acquire topographic projections. Using a combination of GIFM to mark the PC clusters with mGfp and staining for human placental alkaline phosphatase (hAP) in Pcp2-CreER-IRES-hAP transgenic embryos we found that axons from each embryonic PC cluster intermingled with neurons within particular DCN or projected out of the Cb toward the vestibular nuclei by E14.5. These studies show that PC molecular patterning, efferent circuitry, and DCN nucleogenesis occur simultaneously, suggesting a link between these

  18. Cerebellar cortex development in the weaver condition presents regional and age-dependent abnormalities without differences in Purkinje cells neurogenesis. (United States)

    Martí, Joaquín; Santa-Cruz, María C; Hervás, José P; Bayer, Shirley A; Villegas, Sandra


    Ataxias are neurological disorders associated with the degeneration of Purkinje cells (PCs). Homozygous weaver mice (wv/wv) have been proposed as a model for hereditary cerebellar ataxia because they present motor abnormalities and PC loss. To ascertain the physiopathology of the weaver condition, the development of the cerebellar cortex lobes was examined at postnatal day (P): P8, P20 and P90. Three approaches were used: 1) quantitative determination of several cerebellar features; 2) qualitative evaluation of the developmental changes occurring in the cortical lobes; and 3) autoradiographic analyses of PC generation and placement. Our results revealed a reduction in the size of the wv/wv cerebellum as a whole, confirming previous results. However, as distinguished from these reports, we observed that quantified parameters contribute differently to the abnormal growth of the wv/wv cerebellar lobes. Qualitative analysis showed anomalies in wv/wv cerebellar cytoarchitecture, depending on the age and lobe analyzed. Such abnormalities included the presence of the external granular layer after P20 and, at P90, ectopic cells located in the molecular layer following several placement patterns. Finally, we obtained autoradiographic evidence that wild-type and wv/wv PCs presented similar neurogenetic timetables, as reported. However, the innovative character of this current work lies in the fact that the neurogenetic gradients of wv/wv PCs were not modified from P8 to P90. A tendency for the accumulation of late-formed PCs in the anterior and posterior lobes was found, whereas early-generated PCs were concentrated in the central and inferior lobes. These data suggested that wv/wv PCs may migrate properly to their final destinations. The extrapolation of our results to patients affected with cerebellar ataxias suggests that all cerebellar cortex lobes are affected with several age-dependent alterations in cytoarchitectonics. We also propose that PC loss may be regionally

  19. Frequency-dependent reliability of spike propagation is function of axonal voltage-gated sodium channels in cerebellar Purkinje cells. (United States)

    Yang, Zhilai; Wang, Jin-Hui


    The spike propagation on nerve axons, like synaptic transmission, is essential to ensure neuronal communication. The secure propagation of sequential spikes toward axonal terminals has been challenged in the neurons with a high firing rate, such as cerebellar Purkinje cells. The shortfall of spike propagation makes some digital spikes disappearing at axonal terminals, such that the elucidation of the mechanisms underlying spike propagation reliability is crucial to find the strategy of preventing loss of neuronal codes. As the spike propagation failure is influenced by the membrane potentials, this process is likely caused by altering the functional status of voltage-gated sodium channels (VGSC). We examined this hypothesis in Purkinje cells by using pair-recordings at their somata and axonal blebs in cerebellar slices. The reliability of spike propagation was deteriorated by elevating spike frequency. The frequency-dependent reliability of spike propagation was attenuated by inactivating VGSCs and improved by removing their inactivation. Thus, the functional status of axonal VGSCs influences the reliability of spike propagation.

  20. Purkinje-cell-restricted restoration of Kv3.3 function restores complex spikes and rescues motor coordination in Kcnc3 mutants. (United States)

    Hurlock, Edward C; McMahon, Anne; Joho, Rolf H


    The fast-activating/deactivating voltage-gated potassium channel Kv3.3 (Kcnc3) is expressed in various neuronal cell types involved in motor function, including cerebellar Purkinje cells. Spinocerebellar ataxia type 13 (SCA13) patients carrying dominant-negative mutations in Kcnc3 and Kcnc3-null mutant mice both display motor incoordination, suggested in mice by increased lateral deviation while ambulating and slips on a narrow beam. Motor skill learning, however, is spared. Mice lacking Kcnc3 also exhibit muscle twitches. In addition to broadened spikes, recordings of Kcnc3-null Purkinje cells revealed fewer spikelets in complex spikes and a lower intraburst frequency. Targeted reexpression of Kv3.3 channels exclusively in Purkinje cells in Kcnc3-null mice as well as in mice also heterozygous for Kv3.1 sufficed to restore simple spike brevity along with normal complex spikes and to rescue specifically coordination. Therefore, spike parameters requiring Kv3.3 function in Purkinje cells are involved in the ataxic null phenotype and motor coordination, but not motor learning.

  1. Rescue of motor coordination by Purkinje cell-targeted restoration of Kv3.3 channels in Kcnc3-null mice requires Kcnc1. (United States)

    Hurlock, Edward C; Bose, Mitali; Pierce, Ganon; Joho, Rolf H


    The role of cerebellar Kv3.1 and Kv3.3 channels in motor coordination was examined with an emphasis on the deep cerebellar nuclei (DCN). Kv3 channel subunits encoded by Kcnc genes are distinguished by rapid activation and deactivation kinetics that support high-frequency, narrow action potential firing. Previously we reported that increased lateral deviation while ambulating and slips while traversing a narrow beam of ataxic Kcnc3-null mice were corrected by restoration of Kv3.3 channels specifically to Purkinje cells, whereas Kcnc3-mutant mice additionally lacking one Kcnc1 allele were partially rescued. Here, we report mice lacking all Kcnc1 and Kcnc3 alleles exhibit no such rescue. For Purkinje cell output to reach the rest of the brain it must be conveyed by neurons of the DCN or vestibular nuclei. As Kcnc1, but not Kcnc3, alleles are lost, mutant mice exhibit increasing gait ataxia accompanied by spike broadening and deceleration in DCN neurons, suggesting the facet of coordination rescued by Purkinje-cell-restricted Kv3.3 restoration in mice lacking just Kcnc3 is hypermetria, while gait ataxia emerges when additionally Kcnc1 alleles are lost. Thus, fast repolarization in Purkinje cells appears important for normal movement velocity, whereas DCN neurons are a prime candidate locus where fast repolarization is necessary for normal gait patterning.

  2. Rescue of Motor Coordination by Purkinje Cell-Targeted Restoration of Kv3.3 Channels in Kcnc3-Null Mice Requires Kcnc1 (United States)

    Hurlock, Edward C.; Bose, Mitali; Pierce, Ganon


    The role of cerebellar Kv3.1 and Kv3.3 channels in motor coordination was examined with an emphasis on the deep cerebellar nuclei (DCN). Kv3 channel subunits encoded by Kcnc genes are distinguished by rapid activation and deactivation kinetics that support high-frequency, narrow action potential firing. Previously we reported that increased lateral deviation while ambulating and slips while traversing a narrow beam of ataxic Kcnc3-null mice were corrected by restoration of Kv3.3 channels specifically to Purkinje cells, whereas Kcnc3-mutant mice additionally lacking one Kcnc1 allele were partially rescued. Here, we report mice lacking all Kcnc1 and Kcnc3 alleles exhibit no such rescue. For Purkinje cell output to reach the rest of the brain it must be conveyed by neurons of the DCN or vestibular nuclei. As Kcnc1, but not Kcnc3, alleles are lost, mutant mice exhibit increasing gait ataxia accompanied by spike broadening and deceleration in DCN neurons, suggesting the facet of coordination rescued by Purkinje-cell-restricted Kv3.3 restoration in mice lacking just Kcnc3 is hypermetria, while gait ataxia emerges when additionally Kcnc1 alleles are lost. Thus, fast repolarization in Purkinje cells appears important for normal movement velocity, whereas DCN neurons are a prime candidate locus where fast repolarization is necessary for normal gait patterning. PMID:20016089

  3. The postnatal development of cerebellar Purkinje cells in the Gottingen minipig estimated with a new stereological sampling technique--the vertical bar fractionator

    DEFF Research Database (Denmark)

    Jelsing, Jacob; Gundersen, Hans Jørgen Gottlieb; Nielsen, Rune


    The postnatal development of total number and perikaryon volume of cerebellar Purkinje cells was estimated in the Gottingen minipig cerebellar cortex using a new stereological approach, the vertical bar fractionator. Data were obtained from the brains of five neonate and five adult female Gotting...

  4. Anti-Yo antibody uptake and interaction with its intracellular target antigen causes Purkinje cell death in rat cerebellar slice cultures: a possible mechanism for paraneoplastic cerebellar degeneration in humans with gynecological or breast cancers.

    Directory of Open Access Journals (Sweden)

    John E Greenlee

    Full Text Available Anti-Yo antibodies are immunoglobulin G (IgG autoantibodies reactive with a 62 kDa Purkinje cell cytoplasmic protein. These antibodies are closely associated with paraneoplastic cerebellar degeneration in the setting of gynecological and breast malignancies. We have previously demonstrated that incubation of rat cerebellar slice cultures with patient sera and cerebrospinal fluid containing anti-Yo antibodies resulted in Purkinje cell death. The present study addressed three fundamental questions regarding the role of anti-Yo antibodies in disease pathogenesis: 1 Whether the Purkinje cell cytotoxicity required binding of anti-Yo antibody to its intraneuronal 62 kDa target antigen; 2 whether Purkinje cell death might be initiated by antibody-dependent cellular cytotoxicity rather than intracellular antibody binding; and 3 whether Purkinje cell death might simply be a more general result of intracellular antibody accumulation, rather than of specific antibody-antigen interaction. In our study, incubation of rat cerebellar slice cultures with anti-Yo IgG resulted in intracellular antibody binding, and cell death. Infiltration of the Purkinje cell layer by cells of macrophage/microglia lineage was not observed until extensive cell death was already present. Adsorption of anti-Yo IgG with its 62 kDa target antigen abolished both antibody accumulation and cytotoxicity. Antibodies to other intracellular Purkinje cell proteins were also taken up by Purkinje cells and accumulated intracellularly; these included calbindin, calmodulin, PCP-2, and patient anti-Purkinje cell antibodies not reactive with the 62 kDa Yo antigen. However, intracellular accumulation of these antibodies did not affect Purkinje cell viability. The present study is the first to demonstrate that anti-Yo antibodies cause Purkinje cell death by binding to the intracellular 62 kDa Yo antigen. Anti-Yo antibody cytotoxicity did not involve other antibodies or factors present in patient

  5. Alternative splicing generates a smaller assortment of CaV2.1 transcripts in cerebellar Purkinje cells than in the cerebellum. (United States)

    Kanumilli, Srinivasan; Tringham, Elizabeth W; Payne, C Elizabeth; Dupere, Jonathan R B; Venkateswarlu, Kanamarlapudi; Usowicz, Maria M


    P/Q-type calcium channels control many calcium-driven functions in the brain. The CACNA1A gene encoding the pore-forming CaV2.1 (alpha1A) subunit of P/Q-type channels undergoes alternative splicing at multiple loci. This results in channel variants with different phenotypes. However, the combinatorial patterns of alternative splice events at two or more loci, and hence the diversity of CaV2.1 transcripts, are incompletely defined for specific brain regions and types of brain neurons. Using RT-PCR and splice variant-specific primers, we have identified multiple CaV2.1 transcript variants defined by different pairs of splice events in the cerebellum of adult rat. We have uncovered new splice variations between exons 28 and 34 (some of which predict a premature stop codon) and a new variation in exon 47 (which predicts a novel extended COOH-terminus). Single cell RT-PCR reveals that each individual cerebellar Purkinje neuron also expresses multiple alternative CaV2.1 transcripts, but the assortment is smaller than in the cerebellum. Two of these variants encode different extended COOH-termini which are not the same as those previously reported in Purkinje cells of the mouse. Our patch-clamp recordings show that calcium channel currents in the soma and dendrites of Purkinje cells are largely inhibited by a concentration of omega-agatoxin IVA selective for P-type over Q-type channels, suggesting that the different transcripts may form phenotypic variants of P-type calcium channels in Purkinje cells. These results expand the known diversity of CaV2.1 transcripts in cerebellar Purkinje cells, and propose the selective expression of distinct assortments of CaV2.1 transcripts in different brain neurons and species.

  6. Critical role of JSAP1 and JLP in axonal transport in the cerebellar Purkinje cells of mice. (United States)

    Sato, Tokiharu; Ishikawa, Momoe; Yoshihara, Toru; Nakazato, Ryota; Higashida, Haruhiro; Asano, Masahide; Yoshioka, Katsuji


    JNK/stress-activated protein kinase-associated protein 1 (JSAP1) and JNK-associated leucine zipper protein (JLP) are structurally related scaffolding proteins that are highly expressed in the brain. Here, we found that JSAP1 and JLP play functionally redundant and essential roles in mouse cerebellar Purkinje cell (PC) survival. Mice containing PCs with deletions in both JSAP1 and JLP exhibited PC axonal dystrophy, followed by gradual, progressive neuronal loss. Kinesin-1 cargoes accumulated selectively in the swollen axons of Jsap1/Jlp-deficient PCs. In addition, autophagy inactivation in these mice markedly accelerated PC degeneration. These findings suggest that JSAP1 and JLP play critical roles in kinesin-1-dependent axonal transport, which prevents brain neuronal degeneration. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  7. Preferential Transport and Metabolism of Glucose in Bergmann Glia over Purkinje Cells: A Multiphoton Study of Cerebellar Slices

    Institute of Scientific and Technical Information of China (English)



    了解不同类型的细胞如何处理葡萄糖有助于解释能量供应是如何是如何根据大脑能量需求来进行调整的.荧光追踪结合共聚焦显微镜技术已用于研究培养的脑细胞摄取葡萄糖的实时动态过程.本文采用这种技术利用多光子显微镜观察急性制备的大鼠小脑脑片.带荧光的葡萄糖类似物2NBDG和6NBDG在小脑皮质的分子层中的转运速度比其在蒲肯野细胞胞体和颗粒细胞中快若干倍.洗脱游离示踪剂后,可见大部分磷酸化示踪剂都位于Bergmann胶质细胞,用胶质细胞标记物sulforhodamine 101免疫染色后进一步确认这一结果.有效回收荧光光漂白后显示,2NBDG-P可通过Bergmann胶质细胞之间的缝隙连接沿着分子层水平扩散.本文的结果表明在急性小脑切片中,Bergmann胶质细胞对葡萄糖的转运能力和糖酵解率高于蒲肯野细胞若干倍.由于小脑主要由葡萄糖提供能量,蒲肯野神经元被认为比Bergmann胶质细胞更耗能量,这些结果表明,在胶质细胞和神经元之间存在类似乳酸的能量代谢物介导的环路.%Knowing how different cell types handle glucose should help to decipher how energy supply is adjusted to energy demand in the brain. Previously, the uptake of glucose by cultured brain cells was studied in real-time using fluorescent tracers and confocal microscopy. Here, we have adapted this technique to acute slices prepared from the rat cerebellum by means of multiphoton microscopy. The transport of the fluorescent glucose analogs 2NBDG and 6NBDG was several-fold faster in the molecular layer of the cerebellar cortex than in Purkinje cell somata and granule cells. After washout of free tracer, it became apparent that most phosphorylated tracer was located in Bergmann glia, which was confirmed by counterstaining with the glial marker sulforhodamine 101. The effective recovery of fluorescence after photobleaching showed that 2NBDG-P can diffuse

  8. Motor dysfunction and altered synaptic transmission at the parallel fiber-Purkinje cell synapse in mice lacking potassium channels Kv3.1 and Kv3.3. (United States)

    Matsukawa, Hiroshi; Wolf, Alexander M; Matsushita, Shinichi; Joho, Rolf H; Knöpfel, Thomas


    Micelacking both Kv3.1 and both Kv3.3 K+ channel alleles display severe motor deficits such as tremor, myoclonus, and ataxic gait. Micelacking one to three alleles at the Kv3.1 and Kv3.3 loci exhibit in an allele dose-dependent manner a modest degree of ataxia. Cerebellar granule cells coexpress Kv3.1 and Kv3.3 K+ channels and are therefore candidate neurons that might be involved in these behavioral deficits. Hence, we investigated the synaptic mechanisms of transmission in the parallel fiber-Purkinje cell system. Action potentials of parallel fibers were broader in mice lacking both Kv3.1 and both Kv3.3 alleles and in mice lacking both Kv3.1 and a single Kv3.3 allele compared with those of wild-type mice. The transmission of high-frequency trains of action potentials was only impaired at 200 Hz but not at 100 Hz in mice lacking both Kv3.1 and Kv3.3 genes. However, paired-pulse facilitation (PPF) at parallel fiber-Purkinje cell synapses was dramatically reduced in a gene dose-dependent manner in mice lacking Kv3.1 or Kv3.3 alleles. Normal PPF could be restored by reducing the extracellular Ca2+ concentration indicating that increased activity-dependent presynaptic Ca2+ influx, at least in part caused the altered PPF in mutant mice. Induction of metabotropic glutamate receptor-mediated EPSCs was facilitated, whereas longterm depression was not impaired but rather facilitated in Kv3.1/Kv3.3 double-knockout mice. These results demonstrate the importance of Kv3 potassium channels in regulating the dynamics of synaptic transmission at the parallel fiber-Purkinje cell synapse and suggest a correlation between short-term plasticity at the parallel fiber-Purkinje cell synapse and motor performance.

  9. Pairing-specific long-term depression of Purkinje cell excitatory postsynaptic potentials results from a classical conditioning procedure in the rabbit cerebellar slice. (United States)

    Schreurs, B G; Oh, M M; Alkon, D L


    1. Using a rabbit cerebellar slice preparation, we stimulated a classical conditioning procedure by stimulating parallel fiber inputs to Purkinje cells with the use of a brief, high-frequency train of eight constant-current pulses 80 ms before climbing fiber inputs to the same Purkinje cell were stimulated with the use of a brief, lower frequency train of three constant-current pulses. In all experiments, we assessed the effects of stimulation by measuring the peak amplitude of Purkinje cell excitatory postsynaptic potentials (EPSPs) to single parallel fiber test pulses. 2. Intradendritically recorded Purkinje cell EPSPs underwent a long-term (> 20 min) reduction in peak amplitude (30%) after paired stimulation of the parallel and climbing fibers but not after unpaired or parallel fiber alone stimulation. We call this phenomenon pairing-specific long-term depression (PSD). 3. Facilitation of the peak amplitude of a second EPSP elicited by a parallel fiber train occurred both before and after paired stimulation suggesting that the locus of depression was not presynaptic. Depression of the peak amplitude of a depolarizing response to focal application of glutamate following pairings of parallel and climbing fiber stimulation added support to a suggested postsynaptic locus of the PSD effect. 4. The application of aniracetam potentiated EPSP peak amplitude by 40%, but these values returned to baseline as a result of pairings. With the removal of aniracetam from the bath 20 min after pairings, normal levels of pairing-specific EPSP depression were observed, indicating that the effect did not result from direct desensitization of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-proprionic acid (AMPA) receptors. 5. Incubation of slices in the protein kinase inhibitor H-7 potentiated EPSP peak amplitudes slightly (9%), but peak amplitudes returned to baseline levels after pairings. The net reduction in EPSP peak amplitude of classical conditioning.

  10. Development of "Pinceaux" formations and dendritic translocation of climbing fibers during the acquisition of the balance between glutamatergic and gamma-aminobutyric acidergic inputs in developing Purkinje cells. (United States)

    Sotelo, Constantino


    The acquisition of the dynamic balance between excitation and inhibition in developing Purkinje cells, necessary for their proper function, is analyzed. Newborn (P0) mouse cerebellum contains glutamatergic (VGLUT2-IR) and gamma-aminobutyric acid (GABA)-ergic (VIAAT-IR) axons. The former prevail and belong to climbing fibers, whereas the latter neither colabel with calbindin-expressing fibers nor belong to axons of the cortical GABAergic interneurons. During the first postnatal week, VIAAT-IR axons in the Purkinje cell neighborhood remains very low, and the first synapses with basket fibers are formed at P7, when climbing fibers have already established dense pericellular nets. The descending basket fibers reach the Purkinje cell axon initial segment by P9, immediately establishing axoaxonic synapses. The pinceaux appear as primitive vortex-like arrangements by P12, and by P20 interbasket fiber septate-like junctions, typical of fully mature pinceaux, are still missing. The climbing fiber's somatodendritic translocation occurs later than expected, after the regression of the multiple innervation, and follows the ascending collaterals of the basket axons, which are apparently the optimal substrate for the proper subcellular targeting of the climbing fibers. These results emphasize that chemical transmission in the axon initial segment precedes the electrical inhibition generated by field effects. In addition, GABAergic Purkinje cells, as opposed to glutamatergic projection neurons in other cortical structures, do not begin to receive their excitation to inhibition balance until the end of the first postnatal week, despite the early presence of potentially functional GABAergic axons that possess the required vesicular transport system.

  11. Effects of low-level x-irradiation on cat cerebella at different postnatal intervals. II. Changes in Purkinje cell morphology

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    Anderson, W.J.; Stromberg, M.W.


    The whole-head of infant kittens was irradiated with fractionated doses of 150 R and 200 R at different postnatal intervals. Experimental age conditions consisted of an irradiated newborn, 1-week, 2-week, 3-week, and a 4-week age condition while the age of sacrifice remained constant at 70 days. The molecular layer thickness was reduced by 47 percent in the newborn, 40 percent in the 1-week group, 17 percent in the 2-week group, 19 percent in the 3-week group and by 9 percent in the 4-week group. An evaluation of Golgi impregnated material revealed that the dendritic arborizations of Purkinje cells were consistently reduced the earlier the age at which radiation was begun. A reduction in spiny branchlets was seen in all of the experimental conditions. Climbing fibers were found to conform to the abnormal dendritic arborizations of the Purkinje cells, and were reduced in complexity in the early radiation treatment groups. This suggested that climbing fibers had no influence upon the dendritic growth pattern, but instead were under the influence of the Purkinje cell dendritic growth.

  12. A vermal Purkinje cell simple spike population response encodes the changes in eye movement kinematics due to smooth pursuit adaptation.

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    Suryadeep eDash


    Full Text Available Smooth pursuit adaptation (SPA is an example of cerebellum-dependent motor learning that depends on the integrity of the oculomotor vermis (OMV. In an attempt to unveil the neuronal basis of the role of the OMV in SPA, we recorded Purkinje cells simple spikes (PC SS of trained monkeys. Individual PC SS exhibited specific changes of their discharge patterns during the course of SPA. However, these individual changes did not provide a reliable explanation of the behavioural changes. On the other hand, the population response of PC SS perfectly reflected the changes resulting from adaptation. Population vector was calculated using all cells recorded independent of their location. A population code conveying the behavioural changes is in full accordance with the anatomical convergence of PC axons on target neurons in the cerebellar nuclei. Its computational advantage is the ease with which it can be adjusted to the needs of the behavior by changing the contribution of individual PC SS based on error feedback.

  13. Kv3.3b expression defines the shape of the complex spike in the Purkinje cell. (United States)

    Veys, Ken; Snyders, Dirk; De Schutter, Erik


    The complex spike (CS) in cerebellar Purkinje Cells (PC) is not an all-or-nothing phenomena as originally proposed, but shows variability depending on the spiking behavior of the Inferior Olive and intrinsic variability in the number and shape of spikelets. The potassium channel Kv3.3b, which has been proposed to undergo developmental changes during the postnatal PC maturation, has been shown to be crucial for the repolarization of the spikelets in the CS. We address here the regulation of the intrinsic CS variability by the expression of inactivating Kv3.3 channels in PCs by combining patch-clamp recordings and single-cell PCR methods on the same neurons, using a technique that we recently optimized to correlate single cell transcription levels with membrane ion channel electrophysiology. We show that while the inactivating TEA sensitive Kv3.3 current peak intensity increases with postnatal age, the channel density does not, arguing against postnatal developmental changes of Kv3.3b expression. Real time PCR of Kv3.3b showed a high variability from cell to cell, correlated with the Kv3.3 current density, and suggesting that there are no mechanisms regulating these currents beyond the mRNA pool. We show a significant correlation between normalized quantity of Kv3.3b mRNA and both the number of CS spikelets and their rate of voltage fluctuation, linking the intrinsic CS shape directly to the Kv3.3b mRNA pool. Comparing the observed cell-to-cell variance with studies on transcriptional noise suggests that fluctuations of the Kv3.3b mRNA pool are possibly not regulated but represent merely transcriptional noise, resulting in intrinsic variability of the CS.

  14. GABA-A Inhibition Shapes the Spatial and Temporal Response Properties of Purkinje Cells in the Macaque Cerebellum

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    Pablo M. Blazquez


    Full Text Available Data from in vitro and anesthetized preparations indicate that inhibition plays a major role in cerebellar cortex function. We investigated the role of GABA-A inhibition in the macaque cerebellar ventral-paraflocculus while animals performed oculomotor behaviors that are known to engage the circuit. We recorded Purkinje cell responses to these behaviors with and without application of gabazine, a GABA-A receptor antagonist, near the recorded neuron. Gabazine increased the neuronal responsiveness to saccades in all directions and the neuronal gain to VOR cancellation and pursuit, most significantly the eye and head velocity sensitivity. L-glutamate application indicated that these changes were not the consequence of increases in baseline firing rate. Importantly, gabazine did not affect behavior or efference copy, suggesting that only local computations were disrupted. Our data, collected while the cerebellum performs behaviorally relevant computations, indicate that inhibition is a potent regulatory mechanism for the control of input-output gain and spatial tuning in the cerebellar cortex.

  15. Facial stimulation induces long-term depression at cerebellar molecular layer interneuron–Purkinje cell synapses in vivo in mice

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    De-Lai eQiu


    Full Text Available Cerebellar long-term synaptic plasticity has been proposed to provide a cellular mechanism for motor learning. Numerous studies have demonstrated the induction and mechanisms of synaptic plasticity at parallel fiber–Purkinje cell (PF–PC, parallel fiber–molecular layer interneurons (PF–MLI and mossy fiber–granule cell (MF–GC synapses, but no study has investigated sensory stimulation-evoked synaptic plasticity at MLI–PC synapses in the cerebellar cortex of living animals. We studied the expression and mechanism of MLI–PC GABAergic synaptic plasticity induced by a train of facial stimulation in urethane-anesthetized mice by cell-attached recordings and pharmacological methods. We found that 1 Hz, but not a 2 Hz or 4 Hz, facial stimulation induced a long-term depression (LTD of GABAergic transmission at MLI–PC synapses, which was accompanied with a decrease in the stimulation-evoked pause of spike firing in PCs, but did not induce a significant change in the properties of the sensory-evoked spike events of MLIs. The MLI–PC GABAergic LTD could be prevented by blocking cannabinoid type 1 (CB1 receptors, and could be pharmacologically induced by a CB1 receptor agonist. Additionally, 1 Hz facial stimulation delivered in the presence of a metabotropic glutamate receptor 1 (mGluR1 antagonist, JNJ16259685, still induced the MLI–PC GABAergic LTD, whereas blocking N-methyl-D-aspartate (NMDA receptors during 1 Hz facial stimulation abolished the expression of MLI–PC GABAergic LTD. These results indicate that sensory stimulation can induce an endocannabinoid (eCB-dependent LTD of GABAergic transmission at MLI–PC synapses via activation of NMDA receptors in cerebellar cortical Crus II in vivo in mice. Our results suggest that the sensory stimulation-evoked MLI–PC GABAergic synaptic plasticity may play a critical role in motor learning in animals.

  16. Selective loss of Purkinje cells in a patient with anti-gliadin-antibody-positive autoimmune cerebellar ataxia

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    Hasegawa Akira


    Full Text Available Abstract The patient was an 84-year-old woman who had the onset of truncal ataxia at age 77 and a history of Basedow's disease. Her ataxic gait gradually deteriorated. She could not walk without support at age 81 and she was admitted to our hospital at age 83. Gaze-evoked nystagmus and dysarthria were observed. Mild ataxia was observed in all limbs. Her deep tendon reflex and sense of position were normal. IgA anti-gliadin antibody, IgG anti-gliadin antibody, anti-SS-A/Ro antibody, anti-SS-B/La antibody and anti-TPO antibody were positive. A conventional brain MRI did not show obvious cerebellar atrophy. However, MRI voxel based morphometry (VBM and SPECT-eZIS revealed cortical cerebellar atrophy and reduced cerebellar blood flow. IVIg treatment was performed and was moderately effective. After her death at age 85, the patient was autopsied. Neuropathological findings were as follows: selective loss of Purkinje cells; no apparent degenerative change in the efferent pathways, such as the dentate nuclei or vestibular nuclei; no prominent inflammatory reaction. From these findings, we diagnosed this case as autoimmune cerebellar atrophy associated with gluten ataxia. All 3 autopsies previously reported on gluten ataxia have noted infiltration of inflammatory cells in the cerebellum. In this case, we postulated that the infiltration of inflammatory cells was not found because the patient's condition was based on humoral immunity. The clinical conditions of gluten ataxia have not yet been properly elucidated, but are expected to be revealed as the number of autopsied cases increases.

  17. Low-threshold Ca2+ currents in dendritic recordings from Purkinje cells in rat cerebellar slice cultures. (United States)

    Mouginot, D; Bossu, J L; Gähwiler, B H


    Voltage-dependent Ca2+ conductances were investigated in Purkinje cells in rat cerebellar slice cultures using the whole-cell and cell-attached configurations of the patch-clamp technique. In the presence of 0.5 mM Ca2+ in the extracellular solution, the inward current activated with a threshold of -55 +/- 1.5 mV and reached a maximal amplitude of 2.3 +/- 0.4 nA at -31 +/- 2 mV. Decay kinetics revealed three distinct components: a fast (24.6 +/- 2 msec time constant), a slow (304 +/- 46 msec time constant), and a nondecaying component. Rundown of the slow and sustained components of the current, or application of antagonists for the P/Q-type Ca2+ channels, allowed isolation of the fast-inactivating Ca2+ current, which had a threshold for activation of -60 mV and reached a maximal amplitude of 0.7 nA at a membrane potential of -33 mV. Both activation and steady-state inactivation of this fast-inactivating Ca2+ current were described with Boltzmann equations, with half-activation and inactivation at -51 mV and -86 mV, respectively. This Ca2+ current was nifedipine-insensitive, but its amplitude was reduced reversibly by bath-application of NiCl2 and amiloride, thus allowing its identification as a T-type Ca2+ current. Channels with a conductance of 7 pS giving rise to a fast T-type ensemble current (insensitive to omega-Aga-IVA) were localized with a high density on the dendritic membrane. Channel activity responsible for the ensemble current sensitive to omega-Aga-IVA was detected with 10 mM Ba2+ as the charge carrier. These channels were distributed with a high density on dendritic membranes and in rare cases were also seen in somatic membrane patches.

  18. Estudo estereológico das células de Purkinje cerebelares submetidas à intoxicação alcoólica em ratos Wistar Stereologic study of the cerebellar Purkinje cells submitted to alcoholic intoxication in Wistar rats

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    Mara Ibis Rodrigues Apfel


    Full Text Available MOTIVO DO ESTUDO: Analisar o efeito do álcool sobre as células de Purkinje de ratos. MÉTODO: Ratos Wistar receberam oralmente soluções alcoólicas em diferentes concentrações 4%, 12% e 24%. Os animais foram sacrificados com 4, 8 e 12 semanas e os cerebelos foram clivados em cortes aleatórios e uniformemente isotrópicos e incluídos em parafina. Cortes de 6µm (H & E foram analisados por estereologia. RESULTADOS: As diferenças entre a densidade por área e densidade de superfície das células de Purkinje de todos os grupos experimentais (E e os respectivos controles (C foram significativas. Com 12 semanas, a densidade volumétrica da célula de Purkinje diminuiu entre os grupos C e E nas concentrações de 4% e 12%, mas não para a concentração de 24%, provavelmente devido a menor ingestão de líquido pelos animais. CONCLUSÃO: O álcool exerceu efeito tóxico sobre o corpo celular da célula de Purkinje nas três concentrações estudadas a partir de 4 semanas.BACKGROUND: to analyze the effect of the alcohol on the cells of Purkinje. METHOD: Wistar rats received alcoholic solutions orally in different concentrations 4%, 12% and 24%. The animals were sacrificed with 4, 8 and 12 weeks and the cerebella were randomly cut and embedded in paraffin. Sections of 6µm (H&E were stereologically analyzed. RESULTS: The differences among the density for area and density of surface of the cells of Purkinje of all of the experimental groups (E and the respective controls (C were significant. With 12 weeks the cell of Purkinje volume density decreased among the groups C and E in the concentrations of 4% and 12%, but not for the concentration of 24%, probably due to smaller liquid ingestion by the animals. CONCLUSION: The alcohol has toxic effect on the Purkinje cellular body in the three studied concentrations from 4 weeks.

  19. Developmental Hypothyroxinemia and Hypothyroidism Reduce Parallel Fiber-Purkinje Cell Synapses in Rat Offspring by Downregulation of Neurexin1/Cbln1/GluD2 Tripartite Complex. (United States)

    Wang, Yuan; Dong, Jing; Wang, Yi; Wei, Wei; Song, Binbin; Shan, Zhongyan; Teng, Weiping; Chen, Jie


    Iodine is a significant micronutrient. Iodine deficiency (ID)-induced hypothyroxinemia and hypothyroidism during developmental period can cause cerebellar dysfunction. However, mechanisms are still unclear. Therefore, the present research aims to study effects of developmental hypothyroxinemia caused by mild ID and hypothyroidism caused by severe ID or methimazole (MMZ) on parallel fiber-Purkinje cell (PF-PC) synapses in filial cerebellum. Maternal hypothyroxinemia and hypothyroidism models were established in Wistar rats using ID diet and deionized water supplemented with different concentrations of potassium iodide or MMZ water. Birth weight and cerebellum weight were measured. We also examined PF-PC synapses using immunofluorescence, and western blot analysis was conducted to investigate the activity of Neurexin1/cerebellin1 (Cbln1)/glutamate receptor d2 (GluD2) tripartite complex. Our results showed that hypothyroxinemia and hypothyroidism decreased birth weight and cerebellum weight and reduced the PF-PC synapses on postnatal day (PN) 14 and PN21. Accordingly, the mean intensity of vesicular glutamate transporter (VGluT1) and Calbindin immunofluorescence was reduced in mild ID, severe ID, and MMZ groups. Moreover, maternal hypothyroxinemia and hypothyroidism reduced expression of Neurexin1/Cbln1/GluD2 tripartite complex. Our study supports the hypothesis that developmental hypothyroxinemia and hypothyroidism reduce PF-PC synapses, which may be attributed to the downregulation of Neurexin1/Cbln1/GluD2 tripartite complex.

  20. Motor learning in common marmosets: vestibulo-ocular reflex adaptation and its sensitivity to inhibitors of Purkinje cell long-term depression. (United States)

    Anzai, Mari; Nagao, Soich


    Adaptation of the horizontal vestibulo-ocular reflex (HVOR) provides an experimental model for cerebellum-dependent motor learning. We developed an eye movement measuring system and a paradigm for induction of HVOR adaptation for the common marmoset. The HVOR gain in dark measured by 10° (peak-to-peak amplitude) and 0.11-0.5Hz turntable oscillation was around unity. The gain-up and gain-down HVOR adaptation was induced by 1h of sustained out-of-phase and in-phase 10°-0.33Hz combined turntable-screen oscillation in the light, respectively. To examine the role of long-term depression (LTD) of parallel fiber-Purkinje cell synapses, we intraperitonially applied T-588 or nimesulide, which block the induction of LTD in vitro or in vivo preparations, 1h before the test of HVOR adaptation. T-588 (3 and 5mg/kg body weight) did not affect nonadapted HVOR gains, and impaired both gain-up and gain-down HVOR adaptation. Nimesulide (3 and 6mg/kg) did not affect nonadapted HVOR gains, and impaired gain-up HVOR adaptation dose-dependently; however, it very little affected gain-down HVOR adaptation. These findings are consistent with the results of our study of nimesulide on the adaptation of horizontal optokinetic response in mice (Le et al., 2010), and support the view that LTD underlies HVOR adaptation.

  1. Understanding the Role of TSC1/2 in Cerebellar Purkinje Neurons (United States)


    AWARD NUMBER: W81XWH-15-1-0189 TITLE: Understanding the role of TSC1/2 in cerebellar Purkinje neurons PRINCIPAL INVESTIGATOR: Mustafa Sahin...5a. CONTRACT NUMBER Understanding the role of TSC1/2 in cerebellar Purkinje neurons 5b. GRANT NUMBER W81XWH-15-1-0189 5c. PROGRAM ELEMENT...Purkinje cells are the sole output neuron of the cerebellum, and previously we have shown that Tsc1 mutant Purkinje cells cause autistic-like

  2. Synaptic responses evoked by tactile stimuli in Purkinje cells in mouse cerebellar cortex Crus II in vivo.

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    Chun-Ping Chu

    Full Text Available BACKGROUND: Sensory stimuli evoke responses in cerebellar Purkinje cells (PCs via the mossy fiber-granule cell pathway. However, the properties of synaptic responses evoked by tactile stimulation in cerebellar PCs are unknown. The present study investigated the synaptic responses of PCs in response to an air-puff stimulation on the ipsilateral whisker pad in urethane-anesthetized mice. METHODS AND MAIN RESULTS: Thirty-three PCs were recorded from 48 urethane-anesthetized adult (6-8-week-old HA/ICR mice by somatic or dendritic patch-clamp recording and pharmacological methods. Tactile stimulation to the ipsilateral whisker pad was delivered by an air-puff through a 12-gauge stainless steel tube connected with a pressurized injection system. Under current-clamp conditions (I = 0, the air-puff stimulation evoked strong inhibitory postsynaptic potentials (IPSPs in the somata of PCs. Application of SR95531, a specific GABA(A receptor antagonist, blocked IPSPs and revealed stimulation-evoked simple spike firing. Under voltage-clamp conditions, tactile stimulation evoked a sequence of transient inward currents followed by strong outward currents in the somata and dendrites in PCs. Application of SR95531 blocked outward currents and revealed excitatory postsynaptic currents (EPSCs in somata and a temporal summation of parallel fiber EPSCs in PC dendrites. We also demonstrated that PCs respond to both the onset and offset of the air-puff stimulation. CONCLUSIONS: These findings indicated that tactile stimulation induced asynchronous parallel fiber excitatory inputs onto the dendrites of PCs, and failed to evoke strong EPSCs and spike firing in PCs, but induced the rapid activation of strong GABA(A receptor-mediated inhibitory postsynaptic currents in the somata and dendrites of PCs in the cerebellar cortex Crus II in urethane-anesthetized mice.

  3. Cbln1 accumulates and colocalizes with Cbln3 and GluRδ2 at parallel fiber-Purkinje cell synapses in the mouse cerebellum


    Miura, Eriko; Matsuda, Keiko; Morgan, James I.; Yuzaki, Michisuke; Watanabe, Masahiko


    Cbln1 (a.k.a. precerebellin) is secreted from cerebellar granule cells as homohexamer or in heteromeric complexes with Cbln3. Cbln1 plays crucial roles in regulating morphological integrity of parallel fiber (PF)-Purkinje cell (PC) synapses and synaptic plasticity; Cbln1-knockout mice display severe cerebellar phenotypes that are essentially indistinguishable from those in glutamate receptor GluRδ2-null mice and include, severe reduction in the number of PF-PC synapses and loss of long-term d...

  4. Pairing of pre- and postsynaptic activities in cerebellar Purkinje cells induces long-term changes in synaptic efficacy in vitro. (United States)

    Crepel, F; Jaillard, D


    1. An in vitro slice preparation of rat cerebellar cortex was used to analyse long-lasting modifications of synaptic transmission at parallel fibre (PF)-Purkinje cell (PC) synapses. These use-dependent changes were induced by pairing PF-mediated EPSPs evoked at low frequency (1 Hz) with different levels of membrane polarization (or bioelectrical activities) of PCs for 15 min. 2. Experiments were performed on forty-eight PCs recorded intracellularly in a conventional perfused chamber, and in fifty other cells maintained in a static chamber either in the presence (n = 21) or in the absence (n = 29) of 400 nM-phorbol 12,13-dibutyrate (PDBu). 3. In these three experimental conditions, PF-mediated EPSPs were always measured on PCs maintained at a holding potential of -75 mV, and further hyperpolarized by constant hyperpolarizing pulses. This allowed us both to test the input resistance of PCs and to avoid their firing during PF-mediated EPSPs. 4. In all cells retained for the present study, latencies of PF-mediated EPSPs evoked at 0.2 Hz were stable during the pre-pairing period, and the same was true for their amplitude and time course. 5. In the perfused chamber, pairing of PF-mediated EPSPs with the same hyperpolarization of PCs as that used for measurements of synaptic responses had no effect on these EPSPs in 30% of PCs. It induced long-term depression (LTD) and long-term potentiation (LTP) in 23 and 47% of the tested cells respectively (n = 17). 6. In the perfused chamber, pairing of PF-mediated EPSPs with moderate depolarization of PCs (n = 19) giving rise to a sustained firing of sodium spikes significantly favoured the appearance of LTP as compared to the previous pairing protocol. However, there were still 27 and 15% of cells which showed no modification and LTD respectively. 7. In contrast, pairing of PF-mediated EPSPs with calcium (Ca2+) spikes evoked by strong depolarization of PCs (n = 12) led to LTD of synaptic transmission in nearly half of the tested

  5. Transferences of Purkinje systems

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    W. F. Harris


    Full Text Available The transferences of heterocentric astigmatic Purkinje systems are special: submatrices B and C, that is, the disjugacy and the divergence of the system, are symmetric and submatrix D (the divarication is the transpose of submatrix A (the dilation.  It is the primary purpose of this paper to provide a proof.  The paper also derives other relationships among the fundamental properties and compact expressions for the transference and optical axis locator of a Purkinje system. (S Afr Optom 2011 70(2 57-60

  6. Tunable Oscillations in the Purkinje Neuron

    CERN Document Server

    Abrams, Ze'ev R; Wang, Yuan; Trauner, Dirk; Zhang, Xiang


    In this paper, we study the dynamics of slow oscillations in Purkinje neurons in vitro, and derive a strong association with a forced parametric oscillator model. We demonstrate the precise rhythmicity of the oscillations in Purkinje neurons, as well as a dynamic tunability of this oscillation using a photo-switchable compound. We show that this slow oscillation can be induced in every Purkinje neuron, having periods ranging between 10-25 seconds. Starting from a Hodgkin-Huxley model, we also demonstrate that this oscillation can be externally modulated, and that the neurons will return to their intrinsic firing frequency after the forced oscillation is concluded. These results signify an additional functional role of tunable oscillations within the cerebellum, as well as a dynamic control of a time scale in the brain in the range of seconds.

  7. Protein-kinase C : its role in activity-dependent Purkinje cell dendritic development and plasticity

    NARCIS (Netherlands)

    Metzger, F; Kapfhammer, JP


    The cerebellum is a central organ in the control of motor learning and performance. In this respect, the cellular plasticity model systems of multiple climbing fiber elimination and long-term depression have been intensively studied. The signalling pathways involved in these plastic changes are now

  8. Constitutive Intracellular Na+ Excess in Purkinje Cells Promotes Arrhythmogenesis at Lower Levels of Stress Than Ventricular Myocytes From Mice With Catecholaminergic Polymorphic Ventricular Tachycardia. (United States)

    Willis, B Cicero; Pandit, Sandeep V; Ponce-Balbuena, Daniela; Zarzoso, Manuel; Guerrero-Serna, Guadalupe; Limbu, Bijay; Deo, Makarand; Camors, Emmanuel; Ramirez, Rafael J; Mironov, Sergey; Herron, Todd J; Valdivia, Héctor H; Jalife, José


    In catecholaminergic polymorphic ventricular tachycardia (CPVT), cardiac Purkinje cells (PCs) appear more susceptible to Ca(2+) dysfunction than ventricular myocytes (VMs). The underlying mechanisms remain unknown. Using a CPVT mouse (RyR2(R4496C+/Cx40eGFP)), we tested whether PC intracellular Ca(2+) ([Ca(2+)]i) dysregulation results from a constitutive [Na(+)]i surplus relative to VMs. Simultaneous optical mapping of voltage and [Ca(2+)]i in CPVT hearts showed that spontaneous Ca(2+) release preceded pacing-induced triggered activity at subendocardial PCs. On simultaneous current-clamp and Ca(2+) imaging, early and delayed afterdepolarizations trailed spontaneous Ca(2+) release and were more frequent in CPVT PCs than CPVT VMs. As a result of increased activity of mutant ryanodine receptor type 2 channels, sarcoplasmic reticulum Ca(2+) load, measured by caffeine-induced Ca(2+) transients, was lower in CPVT VMs and PCs than respective controls, and sarcoplasmic reticulum fractional release was greater in both CPVT PCs and VMs than respective controls. [Na(+)]i was higher in both control and CPVT PCs than VMs, whereas the density of the Na(+)/Ca(2+) exchanger current was not different between PCs and VMs. Computer simulations using a PC model predicted that the elevated [Na(+)]i of PCs promoted delayed afterdepolarizations, which were always preceded by spontaneous Ca(2+) release events from hyperactive ryanodine receptor type 2 channels. Increasing [Na(+)]i monotonically increased delayed afterdepolarization frequency. Confocal imaging experiments showed that postpacing Ca(2+) spark frequency was highest in intact CPVT PCs, but such differences were reversed on saponin-induced membrane permeabilization, indicating that differences in [Na(+)]i played a central role. In CPVT mice, the constitutive [Na(+)]i excess of PCs promotes triggered activity and arrhythmogenesis at lower levels of stress than VMs. © 2016 The Authors.

  9. Constitutive Intracellular Na+ Excess in Purkinje Cells Promotes Arrhythmogenesis at Lower Levels of Stress Than Ventricular Myocytes From Mice With Catecholaminergic Polymorphic Ventricular Tachycardia (United States)

    Willis, B. Cicero; Pandit, Sandeep V.; Ponce-Balbuena, Daniela; Zarzoso, Manuel; Guerrero-Serna, Guadalupe; Limbu, Bijay; Deo, Makarand; Camors, Emmanuel; Ramirez, Rafael J.; Mironov, Sergey; Herron, Todd J.; Valdivia, Héctor H.


    Background— In catecholaminergic polymorphic ventricular tachycardia (CPVT), cardiac Purkinje cells (PCs) appear more susceptible to Ca2+ dysfunction than ventricular myocytes (VMs). The underlying mechanisms remain unknown. Using a CPVT mouse (RyR2R4496C+/Cx40eGFP), we tested whether PC intracellular Ca2+ ([Ca2+]i) dysregulation results from a constitutive [Na+]i surplus relative to VMs. Methods and Results— Simultaneous optical mapping of voltage and [Ca2+]i in CPVT hearts showed that spontaneous Ca2+ release preceded pacing-induced triggered activity at subendocardial PCs. On simultaneous current-clamp and Ca2+ imaging, early and delayed afterdepolarizations trailed spontaneous Ca2+ release and were more frequent in CPVT PCs than CPVT VMs. As a result of increased activity of mutant ryanodine receptor type 2 channels, sarcoplasmic reticulum Ca2+ load, measured by caffeine-induced Ca2+ transients, was lower in CPVT VMs and PCs than respective controls, and sarcoplasmic reticulum fractional release was greater in both CPVT PCs and VMs than respective controls. [Na+]i was higher in both control and CPVT PCs than VMs, whereas the density of the Na+/Ca2+ exchanger current was not different between PCs and VMs. Computer simulations using a PC model predicted that the elevated [Na+]i of PCs promoted delayed afterdepolarizations, which were always preceded by spontaneous Ca2+ release events from hyperactive ryanodine receptor type 2 channels. Increasing [Na+]i monotonically increased delayed afterdepolarization frequency. Confocal imaging experiments showed that postpacing Ca2+ spark frequency was highest in intact CPVT PCs, but such differences were reversed on saponin-induced membrane permeabilization, indicating that differences in [Na+]i played a central role. Conclusions— In CPVT mice, the constitutive [Na+]i excess of PCs promotes triggered activity and arrhythmogenesis at lower levels of stress than VMs. PMID:27169737

  10. 阿片样肽类的微离子透入对猫小脑浦肯野氏细胞的作用%Effects of microiontophoretically-applied opioid peptides on Purkinje cells in the cat cerebellum

    Institute of Scientific and Technical Information of China (English)

    Kyoji TAGUCHI; Kenji ABE; Touichiro CHYUMA; Masatoshi KATO; Toshiro SHIGENAGA; Kazuki KUSHIDA; Toshiyuki CHIKUMA


    AIM: The purpose of the present study was to examine the effects of microiontophoretically-applied opioid peptides on Purkinje cell of the cerebellum. METHODS:The effects of microiontophoretically-applied morphine,leucine-enkephalin ( Leu-Enk ), methionine-enkephalin (Met-Enk), and dynorphin 1- 13 (Dyn) on the spontaneous discharge of Purkinje cells in the cerebellum of the anesthetized cat were examined. RESULTS: Microiontophoretic applications of Leu-Enk and morphine produced inhibitory and excitatory responses, respectively in Purkinje cells. Application of both morphine and Leu-Enk induced dose-dependent responses. The excitatory responses were antagonized by naloxone, whereas the inhibitory responses were not. Bicuculline, a GABA-Aantagonist, completely abolished both the Leu-Enk-and morphine-induced-inhibitory responses. Iontophoretic application of Met-Enk and dyn produced inhibitory responses only. Met-enk- and dyn-induced inhibition was antagonized by naloxone. CONCLUSION: In Purkinje cell activity, microiontophoretically applied Leu-Enk-and morphine-induced excitation is connected with opiate receptors, whereas inhibition is related to the GABA receptor. However, Met-Enk and dyn produced only inhibitory effects via an opiate receptor in the cerebellum of cats.

  11. Progressive Purkinje cell degeneration in tambaleante mutant mice is a consequence of a missense mutation in HERC1 E3 ubiquitin ligase.

    Directory of Open Access Journals (Sweden)

    Tomoji Mashimo


    Full Text Available The HERC gene family encodes proteins with two characteristic domains: HECT and RCC1-like. Proteins with HECT domains have been described to function as ubiquitin ligases, and those that contain RCC1-like domains have been reported to function as GTPases regulators. These two activities are essential in a number of important cellular processes such as cell cycle, cell signaling, and membrane trafficking. Mutations affecting these domains have been found associated with retinitis pigmentosa, amyotrophic lateral sclerosis, and cancer. In humans, six HERC genes have been reported which encode two subgroups of HERC proteins: large (HERC1-2 and small (HERC3-6. The giant HERC1 protein was the first to be identified. It has been involved in membrane trafficking and cell proliferation/growth through its interactions with clathrin, M2-pyruvate kinase, and TSC2 proteins. Mutations affecting other members of the HERC family have been found to be associated with sterility and growth retardation. Here, we report the characterization of a recessive mutation named tambaleante, which causes progressive Purkinje cell degeneration leading to severe ataxia with reduced growth and lifespan in homozygous mice aged over two months. We mapped this mutation in mouse chromosome 9 and then performed positional cloning. We found a GA transition at position 1448, causing a Gly to Glu substitution (Gly483Glu in the highly conserved N-terminal RCC1-like domain of the HERC1 protein. Successful transgenic rescue, with either a mouse BAC containing the normal copy of Herc1 or with the human HERC1 cDNA, validated our findings. Histological and biochemical studies revealed extensive autophagy associated with an increase of the mutant protein level and a decrease of mTOR activity. Our observations concerning this first mutation in the Herc1 gene contribute to the functional annotation of the encoded E3 ubiquitin ligase and underline the crucial and unexpected role of this protein

  12. Kv3.3 channels harbouring a mutation of spinocerebellar ataxia type 13 alter excitability and induce cell death in cultured cerebellar Purkinje cells. (United States)

    Irie, Tomohiko; Matsuzaki, Yasunori; Sekino, Yuko; Hirai, Hirokazu


    The cerebellum plays crucial roles in controlling sensorimotor functions. The neural output from the cerebellar cortex is transmitted solely by Purkinje cells (PCs), whose impairment causes cerebellar ataxia. Spinocerebellar ataxia type 13 (SCA13) is an autosomal dominant disease, and SCA13 patients exhibit cerebellar atrophy and cerebellar symptoms. Recent studies have shown that missense mutations in the voltage-gated K(+) channel Kv3.3 are responsible for SCA13. In the rodent brain, Kv3.3 mRNAs are expressed most strongly in PCs, suggesting that the mutations severely affect PCs in SCA13 patients. Nevertheless, how these mutations affect the function of Kv3.3 in PCs and, consequently, the morphology and neuronal excitability of PCs remains unclear. To address these questions, we used lentiviral vectors to express mutant mouse Kv3.3 (mKv3.3) channels harbouring an R424H missense mutation, which corresponds to the R423H mutation in the Kv3.3 channels of SCA13 patients, in mouse cerebellar cultures. The R424H mutant-expressing PCs showed decreased outward current density, broadened action potentials and elevated basal [Ca(2+)]i compared with PCs expressing wild-type mKv3.3 subunits or those expressing green fluorescent protein alone. Moreover, expression of R424H mutant subunits induced impaired dendrite development and cell death selectively in PCs, both of which were rescued by blocking P/Q-type Ca(2+) channels in the culture conditions. We therefore concluded that expression of R424H mutant subunits in PCs markedly affects the function of endogenous Kv3 channels, neuronal excitability and, eventually, basal [Ca(2+)]i, leading to cell death. These results suggest that PCs in SCA13 patients also exhibit similar defects in PC excitability and induced cell death, which may explain the pathology of SCA13.

  13. Effects of gadolinium-based contrast agents on thyroid hormone receptor action and thyroid hormone-induced cerebellar Purkinje cell morphogenesis

    Directory of Open Access Journals (Sweden)

    Noriyuki Koibuchi


    Full Text Available Gadolinium (Gd-based contrast agents (GBCAs are used in diagnostic imaging to enhance the quality of magnetic resonance imaging or angiography. After intravenous injection, GBCAs can accumulate in the brain. Thyroid hormones (THs are critical to the development and functional maintenance of the central nervous system. TH actions in brain are mainly exerted through nuclear TH receptors (TRs. We examined the effects of GBCAs on TR-mediated transcription in CV-1 cells using transient transfection-based reporter assay and thyroid hormone-mediated cerebellar Purkinje cell morphogenesis in primary culture. We also measured the cellular accumulation and viability of Gd after representative GBCA treatments in cultured CV-1 cells. Both linear (Gd-diethylene triamine pentaacetic acid-bis methyl acid, Gd-DTPA-BMA and macrocyclic (Gd-tetraazacyclododecane tetraacetic acid, Gd-DOTA GBCAs were accumulated without inducing cell death in CV-1 cells. In contrast, Gd chloride (GdCl3 treatment induced approximately 100 times higher Gd accumulation and significantly reduced the number of cells. Low doses of Gd-DTPA-BMA (10−8–10−6 M augmented TR-mediated transcription, but the transcription was suppressed at higher dose (10−5 – 10−4 M, with decreased β-galactosidase activity indicating cellular toxicity. TR-mediated transcription was not altered by Gd-DOTA or GdCl3, but the latter induced a significant reduction in β-galactosidase activity at high doses, indicating cellular toxicity. In cerebellar cultures, the dendrite arborization of Purkinje cells induced by 10-9 M T4 was augmented by low-dose Gd-DTPA-BMA (10−7 M but was suppressed by higher dose (10−5 M. Such augmentation by low-dose Gd-DTPA-BMA was not observed with 10-9 M T3, probably because of the greater dendrite arborization by T3; however, the arborization by T3 was suppressed by a higher dose of Gd-DTPA-BMA (10-5 M as seen in T4 treatment. The effect of Gd-DOTA on dendrite arborization

  14. Pathological changes in Purkinje cells of the cerebellum in acrylamide-intoxicated Ola mice and 6J mice%丙烯酰胺中毒Ola和6J鼠小脑Purkinje细胞的病理改变

    Institute of Scientific and Technical Information of China (English)

    赫秋月; 韩漫夫; 饶明俐


    Objective To observe the differential pathological changes in Purkinje cells of the cerebellum in Ola mice and 6J mice after acrylamide intoxication. Methods Purkinje cells were studied by light microscope and electron microscope. Results Under light microscope,Purkinje cells in 6J mice were densely stained and irregular in cell shape.Under electron microscope,parts of the plasma membrane projection containing some smooth tubular endoplasmic reticula were found occasionally,and the membrane became split and thickened.These abnormal changes were not found in Ola mice. Conclusion Acrylamide intoxication may induce pathological changes in Purkinje cells of 6J mice which may be the pathological basis of ataxia.%目的 观察丙烯酰胺(ACR)中毒后Ola和6J鼠小脑的不同病理改变。方法 采用病理学技术对小脑Purkinje细胞进行光镜和电镜定性分析。结果 光镜下小脑整个Purkinje细胞深染,形态不规则;电镜下偶见胞膜限局性膨出,内含一些管状滑面内质网,在突起的表面部分胞膜分层、变厚。上述改变仅见于6J鼠,而Ola鼠未见异常变化。结论 丙烯酰胺中毒导致6J鼠小脑Purkinje细胞病理改变,这种变化可能是产生共济失调的病理基础。

  15. Effect of long-chain triglyceride lipid emulsion on bupivacaine-induced changes in electrophysiological parameters of rabbit Purkinje cells. (United States)

    Lemoine, Sandrine; Rouet, René; Manrique, Alain; Hanouz, Jean-Luc


    Lipid emulsions are used in the reversal of local anesthetic toxicity. The aim of this study was to investigate the cellular electrophysiological effects of long-chain triglyceride lipid emulsion (LCTE) on cardiac action potential characteristics and conduction disturbances induced by bupivacaine. Purkinje fibers were dissected from the left ventricle of New Zealand white rabbit hearts and superfused with either Tyrode's solution during 30 min (control group), with bupivacaine 10(-6) M, 10(-5) M, and 5.10(-5) M alone, or in the presence of LCTE 0.5%, in addition, LCTE at 0.1%, 0.5%, and 1% was perfused alone. Electrophysiological parameters were recorded using the conventional microelectrode technique (37 °C, 1 Hz frequency). Bupivacaine 5.10(-5) M-induced conduction blocks (8/8 preparations): LCTE 0.5% suppressed the bupivacaine 5.10(-5) M-induced conduction blocks (1/8 preparations). Exposure to bupivacaine 10(-6) M, 10(-5) M, and 5.10(-5) M resulted in a significant decrease in the maximal rate of depolarization (Vmax) (respectively, 25%, 55%, 75%; P bupivacaine 10(-6) M did not significantly decreased Vmax (13%; P = 0.10 vs. control group). The decrease in Vmax resulting from bupivacaine 10(-5) M alone was significantly less in the presence of LCTE 0.5% (P bupivacaine 10(-5) M alone). Exposure to bupivacaine 10(-6) M, 10(-5) M, and 5.10(-5) M alone or in the presence of LCTE 0.5% resulted in a significant decrease in action potential duration measured at 50% and 90% repolarization (APD50 and APD90; P bupivacaine. Moreover, LCTE 0.5% attenuates the decrease in Vmax induced by bupivacaine 10(-6) M and 10(-5) M.

  16. Cbln1 accumulates and colocalizes with Cbln3 and GluRdelta2 at parallel fiber-Purkinje cell synapses in the mouse cerebellum. (United States)

    Miura, Eriko; Matsuda, Keiko; Morgan, James I; Yuzaki, Michisuke; Watanabe, Masahiko


    Cbln1 (a.k.a. precerebellin) is secreted from cerebellar granule cells as homohexamer or in heteromeric complexes with Cbln3. Cbln1 plays crucial roles in regulating morphological integrity of parallel fiber (PF)-Purkinje cell (PC) synapses and synaptic plasticity. Cbln1-knockout mice display severe cerebellar phenotypes that are essentially indistinguishable from those in glutamate receptor GluRdelta2-null mice, and include severe reduction in the number of PF-PC synapses and loss of long-term depression of synaptic transmission. To understand better the relationship between Cbln1, Cbln3 and GluRdelta2, we performed light and electron microscopic immunohistochemical analyses using highly specific antibodies and antigen-exposing methods, i.e. pepsin pretreatment for light microscopy and postembedding immunogold for electron microscopy. In conventional immunohistochemistry, Cbln1 was preferentially associated with non-terminal portions of PF axons in the molecular layer but rarely overlapped with Cbln3. In contrast, antigen-exposing methods not only greatly intensified Cbln1 immunoreactivity in the molecular layer, but also revealed its high accumulation in the synaptic cleft of PF-PC synapses. No such synaptic accumulation was evident at other PC synapses. Furthermore, Cbln1 now came to overlap almost completely with Cbln3 and GluRdelta2 at PF-PC synapses. Therefore, the convergence of all three molecules provides the anatomical basis for a common signaling pathway regulating circuit development and synaptic plasticity in the cerebellum.

  17. A Comparison on Stain of Purkinje Cell in Cerebellum by Two Different Methods%两种染色方法对小脑浦肯野细胞显示效果的比较

    Institute of Scientific and Technical Information of China (English)

    邵康; 张长征; 陈肖肖


    用常规Nissl染色和成年动物Golgi染色方法分别标记小脑浦肯野细胞(Purkinje cell,PC),比较其染色效果,结果显示,常规Nissl染色只能观察到PC胞体,胞体内的胞核及核仁也清晰可见,但树突和轴突不着色;成年动物Golgi染色能清晰地显示PC树突、轴突及树突棘的形态结构,但胞体结构不清楚.

  18. Postnatal Loss of P/Q-type Channels Confined to Rhombic Lip Derived Neurons Alters Synaptic Transmission at the Parallel Fiber to Purkinje Cell Synapse and Replicates Genomic Cacna1a Mutation Phenotype of Ataxia and Seizures in Mice (United States)

    Maejima, Takashi; Wollenweber, Patric; Teusner, Lena U. C.; Noebels, Jeffrey L.; Herlitze, Stefan; Mark, Melanie D.


    Ataxia, episodic dyskinesia and thalamocortical seizures are associated with an inherited loss of P/Q-type voltage-gated Ca2+ channel function. P/Q-type channels are widely expressed throughout the neuraxis, obscuring identification of the critical networks underlying these complex neurological disorders. We recently showed that the conditional postnatal loss of P/Q-type channels in cerebellar Purkinje cells (PCs) in mice (purky) leads to these aberrant phenotypes, suggesting that intrinsic alteration in PC output is a sufficient pathogenic factor for disease initiation. The question arises whether P/Q-type channel deletion confined to a single upstream cerebellar synapse might induce the pathophysiological abnormality of genomically inherited P/Q-type channel disorders. PCs integrate two excitatory inputs, climbing fibers from inferior olive and parallel fibers (PFs) from granule cells (GCs) that receive mossy fiber (MF) input derived from precerebellar nuclei. In this paper, we introduce a new mouse model with a selective knock-out of P/Q-type channels in rhombic lip derived neurons including PF- and MF-pathways (quirky). We found that in quirky mice, PF-PC synaptic transmission is reduced during low-frequency stimulation. Using focal light stimulation of GCs that express optogenetic light-sensitive channels, channelrhodopsin-2, we found that modulation of PC firing via GC input is reduced in quirky mice. Phenotypic analysis revealed that quirky mice display ataxia, dyskinesia and absence epilepsy. These results suggest that developmental alteration of patterned input confined to only one of the main afferent cerebellar excitatory synaptic pathways has a significant role in generating the neurological phenotype associated with the global genomic loss of P/Q-type channel function. PMID:23516282

  19. Profound morphological and functional changes of rodent Purkinje cellsbetween the first and the second postnatal weeks: a metamorphosis?

    Directory of Open Access Journals (Sweden)

    Isabelle eDusart


    Full Text Available Between the first and the second postnatal week, the development of rodent Purkinje cells is characterized by several profound transitions. Purkinje cells acquire their typical dendritic espalier tree morphology and form distal spines. During the first postnatal week, they are multi-innervated by climbing fibers and numerous collateral branches sprout from their axons, whereas from the second postnatal week, the regression of climbing fiber multi-innervation begins, and Purkinje cells become innervated by parallel fibers and inhibitory molecular layer interneurons. Furthermore, their periods of developmental cell death and ability to regenerate their axon stop and their axons become myelinated. Thus a Purkinje cell during the first postnatal week looks and functions differently from a Purkinje cell during the second postnatal week. These fundamental changes occur in parallel with a peak of circulating thyroid hormone in the mouse. All these features suggest to some extent an interesting analogy with amphibian metamorphosis.

  20. IgG from Amyotrophic Lateral Sclerosis Patients Increases Current Through P-Type Calcium Channels in Mammalian Cerebellar Purkinje Cells and in Isolated Channel Protein in Lipid Bilayer (United States)

    Llinas, R.; Sugimori, M.; Cherksey, B. D.; Smith, R. Glenn; Delbono, O.; Stefani, E.; Appel, S.


    The effect of the IgG from amyotrophic lateral sclerosis (ALS) patients was tested on the voltage-dependent barium currents (IBa) in mammalian dissociated Purkinje cells and in isolated P-type calcium channels in lipid bilayers. Whole cell clamp of Purkinje cells demonstrates that ALS IgG increases the amplitude of IBa without modifying their voltage kinetics. This increased IBa could be blocked by a purified nonpeptide toxin from Agelenopsis aperta venom (purified funnel-web spider toxin) or by a synthetic polyamine analog (synthetic funnel-web spider toxin) and by a peptide toxin from the same spider venom, ω-Aga-IVA. Similar results were obtained on single-channel recordings from purified P channel protein. The addition of ALS IgG increased single-channel IBa open time without affecting slope conductance. The results described above were not seen with normal human IgG nor with boiled ALS IgG. It is concluded that ALS IgG enhances inward current through P-type calcium channels. Since P-type Ca2+ channels are present in motoneuron axon terminals, we propose that the enhanced calcium current triggered by ALS IgG may contribute to neuronal damage in ALS.

  1. Dual transgene expression in murine cerebellar Purkinje neurons by viral transduction in vivo.

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    Marie K Bosch

    Full Text Available Viral-vector mediated gene transfer to cerebellar Purkinje neurons in vivo is a promising avenue for gene therapy of cerebellar ataxias and for genetic manipulation in functional studies of animal models of cerebellar disease. Here, we report the results of experiments designed to identify efficient methods for viral transduction of adult murine Purkinje neurons in vivo. For these analyses, several lentiviral and an adeno-associated virus (AAV, serotype 1, vector with various promoter combinations were generated and compared for in situ transduction efficiency, assayed by fluorescent reporter protein expression in Purkinje neurons. Additional experiments were also conducted to identify the optimal experimental strategy for co-expression of two proteins in individual Purkinje neurons. Of the viruses tested, AAV1 with a CAG promoter exhibited the highest specificity for Purkinje neurons. To deliver two proteins to the same Purkinje neuron, several methods were tested, including: an internal ribosome entry site (IRES, a 2A sequence, a dual promoter vector, and co-injection of two viruses. Efficient expression of both proteins in the same Purkinje neuron was only achieved by co-injecting two AAV1-CAG viruses. We found that use of an AAV1-CAG virus outperformed similar lentivirus vectors and that co-injection of two AAV1-CAG viruses could be used to efficiently deliver two proteins to the same Purkinje neuron in adult mice. AAV1 with a CAG promoter is highly efficient and selective at transducing adult cerebellar Purkinje neurons and two AAV-CAG viruses can be used to efficiently express two proteins in the same neuron in vivo.

  2. P/Q-type and T-type calcium channels, but not type 3 transient receptor potential cation channels, are involved in inhibition of dendritic growth after chronic metabotropic glutamate receptor type 1 and protein kinase C activation in cerebellar Purkinje cells. (United States)

    Gugger, Olivia S; Hartmann, Jana; Birnbaumer, Lutz; Kapfhammer, Josef P


    The development of a neuronal dendritic tree is modulated both by signals from afferent fibers and by an intrinsic program. We have previously shown that chronic activation of either type 1 metabotropic glutamate receptors (mGluR1s) or protein kinase C (PKC) in organotypic cerebellar slice cultures of mice and rats severely inhibits the growth and development of the Purkinje cell dendritic tree. The signaling events linking receptor activation to the regulation of dendritic growth remain largely unknown. We have studied whether channels allowing the entry of Ca(2+) into Purkinje cells, in particular the type 3 transient receptor potential cation channels (TRPC3s), P/Q-type Ca(2+) channels, and T-type Ca(2+) channels, might be involved in signaling after mGluR1 or PKC stimulation. We show that the inhibition of dendritic growth seen after mGluR1 or PKC stimulation is partially rescued by pharmacological blockade of P/Q-type and T-type Ca(2+) channels, indicating that activation of these channels mediating Ca(2+) influx contributes to the inhibition of dendritic growth. In contrast, the absence of Ca(2+) -permeable TRPC3s in TRPC3-deficient mice or pharmacological blockade had no effect on mGluR1-mediated and PKC-mediated inhibition of Purkinje cell dendritic growth. Similarly, blockade of Ca(2+) influx through glutamate receptor δ2 or R-type Ca(2+) channels or inhibition of release from intracellular stores did not influence mGluR1-mediated and PKC-mediated inhibition of Purkinje cell dendritic growth. These findings suggest that both T-type and P/Q-type Ca(2+) channels, but not TRPC3 or other Ca(2+) -permeable channels, are involved in mGluR1 and PKC signaling leading to the inhibition of dendritic growth in cerebellar Purkinje cells.

  3. STD-dependent and independent encoding of input irregularity as spike rate in a computational model of a cerebellar nucleus neuron. (United States)

    Luthman, Johannes; Hoebeek, Freek E; Maex, Reinoud; Davey, Neil; Adams, Rod; De Zeeuw, Chris I; Steuber, Volker


    Neurons in the cerebellar nuclei (CN) receive inhibitory inputs from Purkinje cells in the cerebellar cortex and provide the major output from the cerebellum, but their computational function is not well understood. It has recently been shown that the spike activity of Purkinje cells is more regular than previously assumed and that this regularity can affect motor behaviour. We use a conductance-based model of a CN neuron to study the effect of the regularity of Purkinje cell spiking on CN neuron activity. We find that increasing the irregularity of Purkinje cell activity accelerates the CN neuron spike rate and that the mechanism of this recoding of input irregularity as output spike rate depends on the number of Purkinje cells converging onto a CN neuron. For high convergence ratios, the irregularity induced spike rate acceleration depends on short-term depression (STD) at the Purkinje cell synapses. At low convergence ratios, or for synchronised Purkinje cell input, the firing rate increase is independent of STD. The transformation of input irregularity into output spike rate occurs in response to artificial input spike trains as well as to spike trains recorded from Purkinje cells in tottering mice, which show highly irregular spiking patterns. Our results suggest that STD may contribute to the accelerated CN spike rate in tottering mice and they raise the possibility that the deficits in motor control in these mutants partly result as a pathological consequence of this natural form of plasticity.

  4. Ataxia with loss of Purkinje cells in a mouse model for Refsum disease.

    NARCIS (Netherlands)

    Ferdinandusse, S.; Zomer, A.W.M.; Komen, J.C.; van den Brink, C.; Thanos, M.; Hamers, F.P.T.; Wanders, R.J.A.T.; van der Saag, P.T.; Poll-The, B.T.; Brites, P.


    Refsum disease is caused by a deficiency of phytanoyl-CoA hydroxylase (PHYH), the first enzyme of the peroxisomal alpha-oxidation system, resulting in the accumulation of the branched-chain fatty acid phytanic acid. The main clinical symptoms are polyneuropathy, cerebellar ataxia, and retinitis pigm

  5. Ca2+ Signaling in Cerebellar Purkinje Neurons - EDITORIAL (United States)

    Gruol, Donna; Manto, Mario; Haines, Duane


    Tight regulation of calcium (Ca2+) dynamics is critical for all neurons. Ca2+ is a major mediator of cellular excitability, synaptic plasticity, regulation of transcription, amongst others. Recent years have seen major developments in terms of understanding the roles of Ca2+ signals in the cerebellar circuitry, especially for Purkinje neurons and granule cells. The unique morphology of Purkinje neurons serves as a platform to unravel the secrets of Ca2+ homeostasis in cerebellar microcircuits. This special issue covers recent advances in Ca2+ signaling and imaging, and highlights the importance of spatio-temporal compartmentalization underlying Ca2+ dynamics. Sorting out the pieces of the puzzle of homeostatic regulation of Ca2+ remains an instrumental step to start rational therapies of Ca2+ deregulation. PMID:22806980

  6. Frequency of evident Barr and "F" corpuscles in tetraploid Purkinje neurons. (United States)

    Zapata-Gayón, N; Márquez-Monter, H; González-Angulo, A


    A study was carried out with the purpose of establishing the frequency of female sex chromatin (Barr corpuscle) and male sex chromatin or ("F") fluorescent corpuscles in the Purkinje cerebellar neurones, that are tetraploid cells. Two Barr corpuscles were observed in 18 per cent of Purkinje cells in hematoxylin-eosin stained histological sections in five females and none in a similar number of male sex individuals. In the cerebellar smears stained according to Klinger's method, Barr corpuscles were observed in Purkinje cells in 30 per cent of females different to what was observed in male sex individuals. Smears stained with quinacrine dihydrochloride showed two "F" corpuscles in Purkinje cells of male individuals and only one fluorescent corpuscle in a lower percentage of glial cells and of the granule cell layer in this same material. "F" corpuscles were not observed in females. This study shows that in tetraploidy, as the case of Purkinje neurones, an X gonosome is expressed for each set of chromosomes in female individuals and an "F" corpuscle, corresponding to the Y gonosome of each chromosomic set is found in male sex individuals.

  7. Cerebellar Nuclear Neurons Use Time and Rate Coding to Transmit Purkinje Neuron Pauses. (United States)

    Sudhakar, Shyam Kumar; Torben-Nielsen, Benjamin; De Schutter, Erik


    Neurons of the cerebellar nuclei convey the final output of the cerebellum to their targets in various parts of the brain. Within the cerebellum their direct upstream connections originate from inhibitory Purkinje neurons. Purkinje neurons have a complex firing pattern of regular spikes interrupted by intermittent pauses of variable length. How can the cerebellar nucleus process this complex input pattern? In this modeling study, we investigate different forms of Purkinje neuron simple spike pause synchrony and its influence on candidate coding strategies in the cerebellar nuclei. That is, we investigate how different alignments of synchronous pauses in synthetic Purkinje neuron spike trains affect either time-locking or rate-changes in the downstream nuclei. We find that Purkinje neuron synchrony is mainly represented by changes in the firing rate of cerebellar nuclei neurons. Pause beginning synchronization produced a unique effect on nuclei neuron firing, while the effect of pause ending and pause overlapping synchronization could not be distinguished from each other. Pause beginning synchronization produced better time-locking of nuclear neurons for short length pauses. We also characterize the effect of pause length and spike jitter on the nuclear neuron firing. Additionally, we find that the rate of rebound responses in nuclear neurons after a synchronous pause is controlled by the firing rate of Purkinje neurons preceding it.

  8. 小脑肽1对浦肯野细胞突触形成作用的最新研究进展%The Advance on Studies of Cerebellin 1 Effects on Synapses Formation of Purkinje Cells

    Institute of Scientific and Technical Information of China (English)

    遇春霖; 张忠玲


    Cerebellin 1 is a glycoprotein in the cerebellum, which is produced and secreted from granule cells and works as a strong synapse organizer between Purkinje cells and parallel ifbers, the axons of the granule cells. The molecular mechanisms by which Cbln1 induces synapse formation were described and the related literature was reviewed.%小脑肽1是一种小脑中的特异性糖蛋白,由颗粒细胞生成并分泌,在颗粒细胞的平行纤维和浦肯野细胞之间的兴奋性突触形成过程中发挥重要作用。文中将详细描述小脑肽1诱导新生突触形成的分子机制。复习相关方面的文献,就小脑肽1对于浦肯野细胞上突触的形成以及兴奋与抑制传入的调节作用的研究现状作详细介绍。

  9. Intraocular lens alignment from an en face optical coherence tomography image Purkinje-like method (United States)

    Sun, Mengchan; de Castro, Alberto; Ortiz, Sergio; Perez-Merino, Pablo; Birkenfeld, Judith; Marcos, Susana


    Measurement of intraocular lens (IOL) alignment implanted in patients in cataract surgery is important to understand their optical performance. We present a method to estimate tilt and decentration of IOLs based on optical coherence tomography (OCT) images. En face OCT images show Purkinje-like images that correspond to the specular reflections from the corneal and IOL surfaces. Unlike in standard Purkinje-imaging, the tomographic nature of OCT allows unequivocal association of the reflection with the corresponding surface. The locations of the Purkinje-like images are linear combinations of IOL tilt, IOL decentration, and eye rotation. The weighting coefficients depend on the individual anterior segment geometry, obtained from the same OCT datasets. The methodology was demonstrated on an artificial model eye with set amounts of lens tilt and decentration and five pseudophakic eyes. Measured tilt and decentration in the artificial eye differed by 3.7% and 0.9%, respectively, from nominal values. In patients, average IOL tilt and decentration from Purkinje were 3.30±4.68 deg and 0.16±0.16 mm, respectively, and differed on average by 0.5 deg and 0.09 mm, respectively, from direct measurements on distortion-corrected OCT images. Purkinje-based methodology from anterior segment en face OCT imaging provided, therefore, reliable measurements of IOL tilt and decentration.

  10. Interaction of Kv3 potassium channels and resurgent sodium current influences the rate of spontaneous firing of Purkinje neurons. (United States)

    Akemann, Walther; Knöpfel, Thomas


    Purkinje neurons spontaneously generate action potentials in the absence of synaptic drive and thereby exert a tonic, yet plastic, input to their target cells in the deep cerebellar nuclei. Purkinje neurons express two ionic currents with biophysical properties that are specialized for high-frequency firing: resurgent sodium currents and potassium currents mediated by Kv3.3. How these ionic currents determine the intrinsic activity of Purkinje neurons has only partially been understood. Purkinje neurons from mutant mice lacking Kv3.3 have a reduced rate of spontaneous firing. Dynamic-clamp recordings demonstrated that normal firing rates are rescued by inserting artificial Kv3 currents into Kv3.3 knock-out Purkinje neurons. Numerical simulations indicated that Kv3.3 increases the spontaneous firing rate via cooperation with resurgent sodium currents. We conclude that the rate of spontaneous action potential firing of Purkinje neurons is controlled by the interaction of Kv3.3 potassium currents and resurgent sodium currents.

  11. Differential sensitivity of cerebellar purkinje neurons to ethanol in selectively outbred lines of mice: maintenance in vitro independent of synaptic transmission. (United States)

    Basile, A; Hoffer, B; Dunwiddie, T


    The effects of ethanol on spontaneous firing of cerebellar Purkinje neurons were examined in outbred lines of mice (short-sleep, SS; and long-sleep, LS) which exhibit differential behavioral sensitivity to ethanol. In order to determine whether the differences in Purkinje cell ethanol sensitivity which are observed in situ reflect differences in intrinsic properties of Purkinje neurons, we developed an isolated in vitro preparation of mouse cerebellum. Even when synaptic transmission was largely inhibited by elevating Mg2+ and decreasing Ca2+ concentrations, Purkinje cells demonstrated stable long-term firing rates quite similar to those observed in vivo. Purkinje cells responded to superfusion of ethanol with both increases and decreases in firing rate. Inhibition of rate was more commonly observed, and was the only response which was demonstrably dose-dependent. The differential sensitivity to ethanol which we have previously reported in vivo was maintained even under under these conditions, with the LS mice being approximately 5 times more sensitive to the depressant effects of ethanol. In addition, it was shown that ethanol, at the concentrations used in these experiments, decreased the amplitude and increased the duration of single action potentials. Thus, taken together, these results suggest that the differential sensitivity of outbred lines to the soporific effects of ethanol are paralleled by differences in the sensitivity of Purkinje neurons in vitro to superfusion with ethanol. Because these differences can be observed even when synaptic transmission is largely suppressed, it would appear that these differences are intrinsic to the purkinje neurons themselves.

  12. A coupled 3D-1D numerical monodomain solver for cardiac electrical activation in the myocardium with detailed Purkinje network (United States)

    Vergara, Christian; Lange, Matthias; Palamara, Simone; Lassila, Toni; Frangi, Alejandro F.; Quarteroni, Alfio


    We present a model for the electrophysiology in the heart to handle the electrical propagation through the Purkinje system and in the myocardium, with two-way coupling at the Purkinje-muscle junctions. In both the subproblems the monodomain model is considered, whereas at the junctions a resistor element is included that induces an orthodromic propagation delay from the Purkinje network towards the heart muscle. We prove a sufficient condition for convergence of a fixed-point iterative algorithm to the numerical solution of the coupled problem. Numerical comparison of activation patterns is made with two different combinations of models for the coupled Purkinje network/myocardium system, the eikonal/eikonal and the monodomain/monodomain models. Test cases are investigated for both physiological and pathological activation of a model left ventricle. Finally, we prove the reliability of the monodomain/monodomain coupling on a realistic scenario. Our results underlie the importance of using physiologically realistic Purkinje-trees with propagation solved using the monodomain model for simulating cardiac activation.

  13. An effective algorithm for the generation of patient-specific Purkinje networks in computational electrocardiology (United States)

    Palamara, Simone; Vergara, Christian; Faggiano, Elena; Nobile, Fabio


    The Purkinje network is responsible for the fast and coordinated distribution of the electrical impulse in the ventricle that triggers its contraction. Therefore, it is necessary to model its presence to obtain an accurate patient-specific model of the ventricular electrical activation. In this paper, we present an efficient algorithm for the generation of a patient-specific Purkinje network, driven by measures of the electrical activation acquired on the endocardium. The proposed method provides a correction of an initial network, generated by means of a fractal law, and it is based on the solution of Eikonal problems both in the muscle and in the Purkinje network. We present several numerical results both in an ideal geometry with synthetic data and in a real geometry with patient-specific clinical measures. These results highlight an improvement of the accuracy provided by the patient-specific Purkinje network with respect to the initial one. In particular, a cross-validation test shows an accuracy increase of 19% when only the 3% of the total points are used to generate the network, whereas an increment of 44% is observed when a random noise equal to 20% of the maximum value of the clinical data is added to the measures.

  14. Ionic mechanisms of burst firing in dissociated Purkinje neurons. (United States)

    Swensen, Andrew M; Bean, Bruce P


    Cerebellar Purkinje neurons have intrinsic membrane properties that favor burst firing, seen not only during complex spikes elicited by climbing fiber input but also with direct electrical stimulation of cell bodies. We examined the ionic conductances that underlie all-or-none burst firing elicited in acutely dissociated mouse Purkinje neurons by short depolarizing current injections. Blocking voltage-dependent calcium entry by cadmium or replacement of external calcium by magnesium enhanced burst firing, but it was blocked by cobalt replacement of calcium, probably reflecting block of sodium channels. In voltage-clamp experiments, we used the burst waveform of each cell as a voltage command and used ionic substitutions and pharmacological manipulations to isolate tetrodotoxin (TTX)-sensitive sodium current, P-type and T-type calcium current, hyperpolarization-activated cation current (Ih), voltage-activated potassium current, large-conductance calcium-activated potassium current, and small-conductance calcium-activated potassium (SK) current. Measured near the middle of the first interspike interval, TTX-sensitive sodium current carried the largest inward current, and T-type calcium current was also substantial. Current through P-type channels was large immediately after a spike but decayed rapidly. These inward currents were opposed by substantial components of voltage-dependent and calcium-dependent potassium current. Termination of the burst is caused partly by decay of sodium current, together with a progressive buildup of SK current after the first interspike interval. Although burst firing depends on the net balance between multiple large currents flowing after a spike, it is surprisingly robust, probably reflecting complex interactions between the exact voltage waveform and voltage and calcium dependence of the various currents.

  15. 电鱼小脑浦肯野细胞对急性缺氧的功能反应%Functional responses of mormyrid cerebellar Purkinje cells to acute hypoxia insult

    Institute of Scientific and Technical Information of China (English)

    李晶; 师长宏; 成胜权; 李果; 谭小丽; 杜永平; 张月萍


    目的:通过研究急性缺氧对电鱼(mormyrid electric fish)小脑浦肯野细胞(Purkinje cell,PC)的功能影响,阐明缺氧耐受动物神经元在缺氧条件下的电生理特征.方法:采用全细胞膜片钳记录法,观察急性缺氧对电鱼小脑主神经元PC膜电位、兴奋性和平行纤维(parallel fiber,PF)-PC突触传递的影响.结果:(1)短暂缺氧使电鱼小脑PC膜电位发生迅速而持久的超极化,可持续30 min以上,同时伴随自发放电频率的显著下降.谷氨酸AMPA受体阻断剂CNQX不影响PC缺氧性超极化的产生,但可阻断缺氧性超极化的持续存在;而GABAA受体阻断剂Bicuculline则完全阻断缺氧性超极化的产生,并使膜电位在缺氧开始后发生短暂的去极化.(2)缺氧使PC诱发动作电位的阈值增高,频率减低,幅值减小.(3)急性缺氧使刺激PF诱发的PC兴奋性突触后电流(excitatory postsynaptic current,EPSC)呈现长时程增强(long term potentiation,LTP),同时使EPSC双脉冲增强现象(pair-pulse facilitation,PPF)显著衰减.CNQX逆转了PF EPSC的缺氧性LTP,表现为长时程抑制(Long Term Depression,LTD);而Bicuculline则使PF EPSC的缺氧性LTP增强.结论:耐缺氧动物电鱼小脑神经元的缺氧反应特征与哺乳类动物显著不同,AMPA受体和GABAA受体均参与电鱼小脑PC的缺氧性超极化和PF LTP的产生,表明维持GABA能突触和谷氨酸能突触活动的适度平衡,可能是电鱼以及其他耐缺氧动物脑保护机制的关键.%Objective: To evaluate the electrophysiological characteristics of neuron in anorexia tolerant animal under hypoxia condition by discovering the functional responses of Mormyrid cerebellar Purkinje cells (PCs) to acute hypoxia insult. Methods: The whole cell patch clamp was used for the intracellular recording from PCs of the mormyrid cerebellar slices to evaluate the changes of the membrane potential and the excitability of PCs and the PF-PC synaptic transmission induced by acute

  16. Developmental disorders of the brain can be caused by PCBs; low doses of hydroxy-PCBs disrupt thyroid hormone-dependent dendrite formation from Purkinje neurons in culture

    Energy Technology Data Exchange (ETDEWEB)

    Kuroda, Y.; Kimura-Kuroda, J. [Tokyo Metropol. Inst. for Neuroscience, Tokyo (Japan); Nagata, I. [CREST/ JST, Tokyo (Japan)


    Exposure to some environmental chemicals during the perinatal period causes developmental disorders of the brain. Cognitive impairment and hyperactivity in infants were reported in Taiwan, known as Yu-cheng incidents caused by the accidental contamination of polychlorinated biphenyls (PCBs). Together with recent experimental data, Kuroda proposes a hypothesis that spatio-temporal disruptions of developing neuronal circuits by PCB exposure can cause the comobidity of learning disorders (LD), attention deficit hyperactivity disorder (ADHD) and autsm with the co-exposure to other environmental chemicals. PCBs and hydroxylated PCBs (OH-PCBs) have similar chemical structures to thyroid hormones (TH), thyroxine (T4) and triiodothyronine (T3). TH deficiency in the perinatal period causes cretinism children with severe cognitive and mental retardation. In primate model, Rice demonstrates that postnatal exposure to PCBs can dramatically influence later behavioral function. Epidemiological studies also indicate the possible developmental neurotoxicity of PCBs accumulated in human bodies. However, the precise underlying mechanisms and which types of PCB or OH-PCB with such effects have yet to be elucidated. It is important to establish a simple, reproducible, and sensitive in vitro assay for determining the effects of PCBs and OH-PCBs on the development of the central nervous system. Recently Iwasaki et al. established a reporter assay system and disclosed that low doses of PCBs potentially interfere TH-dependent gene expressions. This is the first demonstration that PCBs and OH-PCBs directly affect TH-receptor (TR)-mediated gene expressions crucial to the brain development, through unique mechanism. We also have demonstrated TH-dependent development of Purkinje neurons in vitro using a serum-free chemically defined medium. The degree of dendritic development of Purkinje cells is TH dose-dependent and exhibits high sensitivity in the pM order. Therefore, in the present study

  17. The role of the calcium transporter protein plasma membrane calcium ATPase PMCA2 in cerebellar Purkinje neuron function. (United States)

    Empson, R M; Akemann, W; Knöpfel, Thomas


    Genetic deletion of the plasma membrane calcium ATPase type 2 (PMCA2), a calcium transporter protein, is associated with an overtly ataxic phenotype in mice. PMCA2 is expressed at high levels in cerebellar Purkinje neurons (PNs) where functional integrity is essential for normal cerebellar function. Indeed, loss of PN function accompanies cerebellar ataxia in humans and mouse models. In the ataxic PMCA2 knockout (PMCA2-/-) mouse the ability of the PNs to control their cytosolic calcium levels was severely impaired; basal calcium levels were high and calcium recovery kinetics slow. Whole cell patch clamp recordings from PMCA2-/- PNs revealed that they possessed hyperpolarised membrane potentials, reduced frequency and increased irregularity of spontaneous action potential firing, curtailed complex spikes and sustained calcium-dependent outward K+ currents. We propose that these alterations limit pathological excursions in PN cytosolic calcium as an aid to survival but that they are insufficient to prevent loss of functional cerebellar output.

  18. Evaluation of intraocular lens implant location in the eyeball basing on the Purkinje images (United States)

    Jóźwik, A.; Siedlecki, D.; Zajac, M.


    Intraocular lens (IOL) is an artificial implant substituting natural crystalline lens which is non-transparent due to cataract. Incorrect location of the IOL in the eyeball (e.g. its shift or tilt) causes significant deterioration of patient's vision. The analysis of Purkinje images (i.e. reflections from successive refracting surfaces in the eye) enables to determine the real IOL location and thus helps in evaluating the retinal image quality. The experimental setup for Purkinje images recording consists of illuminator, composed of a number of infrared LEDs, telecentric lens and detector (CCD camera). Analysis of mutual position of particular reflections enables to evaluate the lens location in respect to the corneal axis. The actual measurements are realized on artificial eye model, what allows to estimate the precision of the algorithm applied in the calculations. In the future the experimental set-up will be adapted to measure the eyes of real patients.

  19. Effects of new antiarrhythmic agent SS-68 on excitation conduction, electrical activity in Purkinje fibers and pulmonary veins: Assessment of safety and side effects risk. (United States)

    Bogus, Saida K; Kuzmin, Vladislav S; Abramochkin, Denis V; Suzdalev, Konstantin F; Galenko-Yaroshevsky, Pavel A


    The compound SS-68 has been selected among numerous new derivatives of indole and demonstrated antiarrhythmic effects in animal models. The present study concerns several aspects of SS-68 safety and efficacy as a potential antiarrhythmic drug. The first estimation of atrioventricular conduction in mammalian heart under SS-68 has been carried out; effects of SS-68 in Purkinje fibers and myocardium of pulmonary veins have been investigated. The drug weakly affects cardiac atrioventricular conduction: only high concentrations of SS-68 (≥10 μmol/L) significantly decrease this parameter. Also, the drug weakly affects Purkinje fibers automaticity, but effectively alters action potential waveform in Purkinje fibers in a concentration-dependent manner. SS-68 (0.1-100 μmol/L) failed to induce any early or delayed afterdepolarizations in Purkinje fibers both in basal conditions and under provocation of proarrhythmic activity by norepinephrine (NE). Moreover, 10 μmol/L SS-68 suppressed NE-induced extra-beats and rapid firing in Purkinje fibers. In pulmonary veins only high concentrations of SS-68 significantly increased action potential duration, while lower concentrations (0.1-1 μmol/L) were ineffective. Also, 0.1-100 μmol/L SS-68 was unable to elicit arrhythmogenic alternations of action potential waveform in pulmonary veins. In conclusion, SS-68 has no proarrhythmic effects, such as afterdepolarizations or abnormal automaticity in used experimental models.

  20. Microglia-derived proinflammatory cytokines tumor necrosis factor-alpha and interleukin-1beta induce Purkinje neuronal apoptosis via their receptors in hypoxic neonatal rat brain. (United States)

    Kaur, Charanjit; Sivakumar, Viswanathan; Zou, Zhirong; Ling, Eng-Ang


    The developing cerebellum is extremely vulnerable to hypoxia which can damage the Purkinje neurons. We hypothesized that this might be mediated by tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) derived from activated microglia as in other brain areas. One-day-old rats were subjected to hypoxia following, which the expression changes of various proteins in the cerebellum including hypoxia inducible factor-1α, TNF-α, IL-1β, TNF-R1 and IL-1R1 were analyzed. Following hypoxic exposure, TNF-α and IL-1β immunoexpression in microglia was enhanced coupled by that of TNF-R1 and IL-1R1 in the Purkinje neurons. Along with this, hypoxic microglia in vitro showed enhanced release of TNF-α and IL-1β whose receptor expression was concomitantly increased in the Purkinje neurons. In addition, nitric oxide (NO) level was significantly increased in the cerebellum and cultured microglia subjected to hypoxic exposure. Moreover, cultured Purkinje neurons treated with conditioned medium derived from hypoxic microglia underwent apoptosis but the incidence was significantly reduced when the cells were treated with the same medium that was neutralized with TNF-α/IL-1β antibody. We conclude that hypoxic microglia in the neonatal cerebellum produce increased amounts of NO, TNF-α and IL-1β which when acting via their respective receptors could induce Purkinje neuron death.

  1. Computational analysis of calcium signaling and membrane electrophysiology in cerebellar Purkinje neurons associated with ataxia

    Directory of Open Access Journals (Sweden)

    Brown Sherry-Ann


    important link between calcium metabolism and membrane potential in Purkinje cell function. Conclusion Thus, we have established an initial platform for computational evaluation and prediction of ataxia pathophysiology. Specifically, the model has been used to investigate SCA15/16, SCA1, SCA2, and SCA3. Results suggest that experimental studies treating mouse models of any of these ataxias with appropriately chosen peptides resembling the C-terminal of IP3R1 could adjust receptor sensitivity, and thereby modulate calcium release and normalize IP3 response. In addition, the model supports the hypothesis of IP3R1 supersensitivity in SCA1.

  2. A cerebellar learning model of vestibulo-ocular reflex adaptation in wild-type and mutant mice. (United States)

    Clopath, Claudia; Badura, Aleksandra; De Zeeuw, Chris I; Brunel, Nicolas


    Mechanisms of cerebellar motor learning are still poorly understood. The standard Marr-Albus-Ito theory posits that learning involves plasticity at the parallel fiber to Purkinje cell synapses under control of the climbing fiber input, which provides an error signal as in classical supervised learning paradigms. However, a growing body of evidence challenges this theory, in that additional sites of plasticity appear to contribute to motor adaptation. Here, we consider phase-reversal training of the vestibulo-ocular reflex (VOR), a simple form of motor learning for which a large body of experimental data is available in wild-type and mutant mice, in which the excitability of granule cells or inhibition of Purkinje cells was affected in a cell-specific fashion. We present novel electrophysiological recordings of Purkinje cell activity measured in naive wild-type mice subjected to this VOR adaptation task. We then introduce a minimal model that consists of learning at the parallel fibers to Purkinje cells with the help of the climbing fibers. Although the minimal model reproduces the behavior of the wild-type animals and is analytically tractable, it fails at reproducing the behavior of mutant mice and the electrophysiology data. Therefore, we build a detailed model involving plasticity at the parallel fibers to Purkinje cells' synapse guided by climbing fibers, feedforward inhibition of Purkinje cells, and plasticity at the mossy fiber to vestibular nuclei neuron synapse. The detailed model reproduces both the behavioral and electrophysiological data of both the wild-type and mutant mice and allows for experimentally testable predictions.

  3. Effects of Chronic Ethanol Intoxication on the Ultrastructures of Cerebellar Purkinje Cells in Adult Mice%慢性酒精中毒对成年小鼠小脑浦肯野细胞超微结构的影响

    Institute of Scientific and Technical Information of China (English)

    张长征; 朱庆丰


    目的 观察慢性酒精中毒所致的成年小鼠小脑皮质浦肯野细胞(Purkinje cell,PC)胞体的超微结构变化,探讨其对神经元超微结构的影响方式及生理意义.方法 用15%酒精饲喂3月龄小白鼠3个月,经行为学检测后,取小脑前叶做电镜包埋,切片,染色,透射电镜下观察并拍照.结果 酒精中毒组PC核周质中线粒体膨解,基质囊泡化;高尔基复合体扁平囊扩张;粗面内质网碎裂,核糖体颗粒减少;"空泡变性"出现;双层核膜界限不清;染色质边集等变化.结论 慢性酒精中毒可导致小脑浦肯野细胞多种细胞器出现异常改变,推测这些变化可引起胞内物质合成减少,空间构筑紊乱,神经元死亡,最终导致小脑功能损伤.%Objective We observed chronic ethanol-induced ultrastructural alterations of Purkinje cell (PC) somata in the mouse cerebellar cortex, in order to explore the manner of ethanol impacts on neuronal ultrastructures and the physiological influences underlying these alterations. Methods 3-month old mice were fed with 15% alcohol for 3 months. After the behavioral test to manifest the symptoms of ethanol intoxication, the anterior lobe from each mouse cerebellum was selected for embedding , sectioning, and staining. Undera transmission electron microscope, the organelles of PC somata were observed and photos were taken. Results The organelles in ethanol-intoxicated PCs exhibited the following changes: the mitochondria swelled and the matrix decomposed; the sacs of Golgi apparatus dilated; the rough endoplasmic reticulum (rER) collapsed, accompanied with a great loss of the ribosomes; the "vacuolation" emerged;the double nuclear membrane became illegible; and the chromatin marginally condensed in the nucleus.Conclusion Chronic ethanol intoxication induces degenerative alterations in the organelles of cerebellar PCs, which might result in the decrease in substance synthesis, the disorder in intraneuronal configuration, the

  4. How the Purkinje System Determines the Ventricular Activation Sequence (United States)


    Zipes, Purkinje- muscle coupling and endocardial response to hyperkalemia , hypoxia, and acidosis Am.J.Physiol., vol. 247, pp. H303-H3111984. [12...R.D. Veenstra, R.W. Joyner, R.T. Wiedmann, M.L. Young, and R.C. Tan, Effects of hypoxia, hyperkalemia , and metabolic acidosis on canine subendocardial

  5. Distribution and Structure of Purkinje Fibers in the Heart of Ostrich (Struthio camelus with the Special References on the Ultrastructure

    Directory of Open Access Journals (Sweden)

    Paria Parto


    Full Text Available Purkinje fibers or Purkinje cardiomyocytes are part of the whole complex of the cardiac conduction system, which is today classified as specific heart muscle tissue responsible for the generation of the heart impulses. From the point of view of their distribution, structure and ultrastructural composition of the cardiac conduction system in the ostrich heart were studied by light and electron microscopy. These cells were distributed in cardiac conducting system including SA node, AV node, His bundle and branches as well as endocardium, pericardium, myocardium around the coronary arteries, moderator bands, white fibrous sheet in right atrium, and left septal attachment of AV valve. The great part of the Purkinje fiber is composed of clear, structure less sarcoplasm, and the myofibrils tend to be confined to a thin ring around the periphery of the cells. They have one or more large nuclei centrally located within the fiber. Ultrastructurally, they are easily distinguished. The main distinction feature is the lack of electron density and having a light appearance, due to the absence of organized myofibrils. P-cells usually have two nuclei with a mass of short, delicate microfilaments scattered randomly in the cytoplasm; they contain short sarcomeres and myofibrillar insertion plaque. They do not have T-tubules.

  6. Posturography of ataxia induced by Coriolis- and Purkinje-effects. (United States)

    Fitger, C; Brandt, T


    Vestibular Coriolis- and Purkinje-effect, which are known to induce vertigo, were investigated with respect to body posture. One aim of this investigation was to provide information concerning clinical vertigo symptoms. Standing on a rotatable stabilometer, 25 healthy subjects had to execute lateral head tilts during (Coriolis), or after (Purkinje), rotation varied with different constant velocities. The conditions were varied with respect to eyes open vs. eyes closed, head upright vs. head tilt to the right and left, direction of rotation clockwise vs. counterclockwise, active vs. passive head tilt, and active vs. passive body rotation. The results supported the expectation that destabilization was less severe with open than with closed eyes and that sway amplitudes were increased after head tilt as well as with a higher velocity of rotation. The direction of the induced body shift was, as expected, opposite to the initial vestibular stimulus. A forward shift after stop without head tilt was frequently found, being independent of the previous direction of rotation. Reported perceptions coincided mostly not with the initial vestibular signal but rather with the actual movement of compensation. Active instead of passive movements did not produce clearly different effects. The Purkinje experiment appeared to be equivalent to the situation when a patient with an acute lesion of a horizontal vestibular canal bends his head. The stabilogram under this condition may allow a prediction of the side of the lesion.

  7. Activation of steroid-sensitive TRPM3 channels potentiates glutamatergic transmission at cerebellar Purkinje neurons from developing rats. (United States)

    Zamudio-Bulcock, Paula A; Everett, Julie; Harteneck, Christian; Valenzuela, C Fernando


    The functional implications of transient receptor potential melastatin 3 (TRPM3) activation, the most recently described member of the melastatin subfamily of cation permeable TRP channels, have begun to be elucidated in recent years. The discovery of TRPM3 activation by the steroid pregnenolone sulfate (PregS) has shed new light on the physiological role of this channel. For example, TRPM3 activation enhances insulin secretion from β pancreatic cells, induces contraction of vascular smooth muscle, and is also involved in the detection of noxious heat. Although TRPM3 expression has been detected in several regions of the developing and mature brain, little is known about the roles of TRPM3 in brain physiology. In this study, we demonstrate the abundant expression of TRPM3 steroid-sensitive channels in the developing cerebellar cortex. We also show that TRPM3-like channels are expressed at glutamatergic synapses in neonatal Purkinje cells. We recently showed that PregS potentiates spontaneous glutamate release onto neonatal Purkinje cells during a period of active glutamatergic synapse formation; we now show that this effect of PregS is mediated by TRPM3-like channels. Mefenamic acid, a recently discovered TRPM3 antagonist, blocked the effect of PregS on glutamate release. The PregS effect on glutamate release was mimicked by other TRPM3 agonists (nifedipine and epipregnanolone sulfate) but not by a TRMP3-inactive steroid (progesterone). Our findings identify TRPM3 channels as novel modulators of glutamatergic transmission in the developing brain.

  8. Electrophysiological effects of haloperidol on isolated rabbit Purkinje fibers and guinea pigs papillary muscles under normal and simulated ischemia

    Institute of Scientific and Technical Information of China (English)

    Dong YAN; Lu-feng CHENG; Hong-yan SONG; Subat TURDI; Parhat KERRAM


    Aim: Overdoses of haloperidol are associated with major ventricular arrhythmias,cardiac conduction block, and sudden death. The aim of this experiment was to study the effect of haloperidol on the action potentials in cardiac Purkinje fibers and papillary muscles under normal and simulated ischemia conditions in rabbits and guinea pigs. Methods: Using the standard intracellular microelectrode technique, we examined the effects of haloperidol on the action potential param-eters [action potential amplitude (APA), phase 0 maximum upstroke velocity (Vmax),action potential amplitude at 90% of repolarization (APD90), and effective refrac-tory period (ERP)] in rabbit cardiac Purkinje fibers and guinea pig cardiac papillary cells, in which both tissues were under simulated ischemic conditions. Results: Under ischemic conditions, different concentrations of haloperidol depressed APA and prolonged APD90 in a concentration-dependent manner in rabbit Purkinje fibers. Haloperidol (3 μmol/L) significantly depressed APA and prolonged APD90,and from 1 μmol/L, haloperidol showed significant depression on Vmax; ERP was not significantly affected. In guinea pig cardiac papillary muscles, the thresholds of significant reduction in APA, Vmax, EPR, and APD90 were 10, 0.3, 1, and 1 μmol/L, respectively, for haloperidol. Conclusion: Compared with cardiac con-ductive tissues, papillary muscles were more sensitive to ischemic conditions. Under ischemia, haloperidol prolonged ERP and APD90 in a concentration-depen-dent manner and precipitated the decrease in Vmax induced by ischemia. The shortening of ERP and APD90 in papillary muscle action potentials may be inhibi-ted by haloperidol.

  9. Functional effects of the late sodium current inhibition by AZD7009 and lidocaine in rabbit isolated atrial and ventricular tissue and Purkinje fibre. (United States)

    Persson, Frida; Andersson, Birgit; Duker, Göran; Jacobson, Ingemar; Carlsson, Leif


    AZD7009 (tert-Butyl-2-(7-[(2S)-3-(4-cyanophenoxy)-2-hydroxypropyl]-9-oxa-3,7-diazabicyclo[3.3.1]non-3-yl)ethylcarbamate) is an antiarrhythmic agent that increases atrial refractoriness, shows high antiarrhythmic efficacy and has low proarrhythmic potential. This study was primarily undertaken to determine the effects of AZD7009 on the late sodium current and to examine the impact of late sodium current inhibition on action potential duration in various myocardial cells. AZD7009 inhibited the late sodium current in Chinese Hamster Ovary K1 (CHO K1) cells expressing hNa(v)1.5 with an IC(50) of 11+/-2 microM. The late sodium current in isolated rabbit atrial and ventricular myocytes was also concentration dependently inhibited by AZD7009. Action potentials were recorded during exposure to 5 microM E-4031 (1-[2-(6-methyl-2pyridyl)ethyl]-4-(4-methylsulfonyl aminobenzoyl)piperidine), a compound that selectively inhibits the rapid delayed rectifier potassium current (I(Kr)), and to E-4031 in combination with AZD7009 or lidocaine in rabbit atrial and ventricular tissue and Purkinje fibres. In Purkinje fibres, but not in ventricular tissue, AZD7009 and lidocaine attenuated the E-4031-induced action potential duration prolongation. In atrial cells, AZD7009, but not lidocaine, further prolonged the E-4031-induced action potential duration. E-4031 induced early afterdepolarisations (EADs) in Purkinje fibres, EADs that were totally suppressed by AZD7009 or lidocaine. In conclusion, excessive action potential duration prolongation induced by E-4031 was attenuated by AZD7009 and lidocaine in rabbit Purkinje fibre, but not in atrial or ventricular tissue, most likely by inhibiting the late sodium current. Furthermore, the opposite effect by AZD7009 on action potential duration in atrial tissue suggests that AZD7009, in addition to inhibiting I(Kr), also inhibits other repolarising currents in the atria.

  10. Action potentials initiate in the axon initial segment and propagate through axon collaterals reliably in cerebellar Purkinje neurons. (United States)

    Foust, Amanda; Popovic, Marko; Zecevic, Dejan; McCormick, David A


    Purkinje neurons are the output cells of the cerebellar cortex and generate spikes in two distinct modes, known as simple and complex spikes. Revealing the point of origin of these action potentials, and how they conduct into local axon collaterals, is important for understanding local and distal neuronal processing and communication. By using a recent improvement in voltage-sensitive dye imaging technique that provided exceptional spatial and temporal resolution, we were able to resolve the region of spike initiation as well as follow spike propagation into axon collaterals for each action potential initiated on single trials. All fast action potentials, for both simple and complex spikes, whether occurring spontaneously or in response to a somatic current pulse or synaptic input, initiated in the axon initial segment. At discharge frequencies of less than approximately 250 Hz, spikes propagated faithfully through the axon and axon collaterals, in a saltatory manner. Propagation failures were only observed for very high frequencies or for the spikelets associated with complex spikes. These results demonstrate that the axon initial segment is a critical decision point in Purkinje cell processing and that the properties of axon branch points are adjusted to maintain faithful transmission.

  11. Rethinking cell growth models. (United States)

    Kafri, Moshe; Metzl-Raz, Eyal; Jonas, Felix; Barkai, Naama


    The minimal description of a growing cell consists of self-replicating ribosomes translating the cellular proteome. While neglecting all other cellular components, this model provides key insights into the control and limitations of growth rate. It shows, for example, that growth rate is maximized when ribosomes work at full capacity, explains the linear relation between growth rate and the ribosome fraction of the proteome and defines the maximal possible growth rate. This ribosome-centered model also highlights the challenge of coordinating cell growth with related processes such as cell division or nutrient production. Coordination is promoted when ribosomes don't translate at maximal capacity, as it allows escaping strict exponential growth. Recent data support the notion that multiple cellular processes limit growth. In particular, increasing transcriptional demand may be as deleterious as increasing translational demand, depending on growth conditions. Consistent with the idea of trade-off, cells may forgo maximal growth to enable more efficient interprocess coordination and faster adaptation to changing conditions. © FEMS 2016. All rights reserved. For permissions, please e-mail:

  12. Voltage-dependent potassium currents during fast spikes of rat cerebellar Purkinje neurons: inhibition by BDS-I toxin. (United States)

    Martina, Marco; Metz, Alexia E; Bean, Bruce P


    We characterized the kinetics and pharmacological properties of voltage-activated potassium currents in rat cerebellar Purkinje neurons using recordings from nucleated patches, which allowed high resolution of activation and deactivation kinetics. Activation was exceptionally rapid, with 10-90% activation in about 400 mus at +30 mV, near the peak of the spike. Deactivation was also extremely rapid, with a decay time constant of about 300 mus near -80 mV. These rapid activation and deactivation kinetics are consistent with mediation by Kv3-family channels but are even faster than reported for Kv3-family channels in other neurons. The peptide toxin BDS-I had very little blocking effect on potassium currents elicited by 100-ms depolarizing steps, but the potassium current evoked by action potential waveforms was inhibited nearly completely. The mechanism of inhibition by BDS-I involves slowing of activation rather than total channel block, consistent with the effects described in cloned Kv3-family channels and this explains the dramatically different effects on currents evoked by short spikes versus voltage steps. As predicted from this mechanism, the effects of toxin on spike width were relatively modest (broadening by roughly 25%). These results show that BDS-I-sensitive channels with ultrafast activation and deactivation kinetics carry virtually all of the voltage-dependent potassium current underlying repolarization during normal Purkinje cell spikes.

  13. Is bilirubin able to affect the cell cycle in Gunn rat brain? - An in vivo and in vitro study -


    Robert, Maria Celeste


    The hyperbilirubinemic jj Gunn rat is a well established animal model for Crigler-Najjar type I Syndrome and neonatal jaundice. Similarly to humans, they present neurological deficits and what is more a marked cerebellar hypoplasia with a prominent loss and degeneration of Purkinje cells and granule neurons. Since high levels of bilirubin have been proven to arrest the cell cycle progression, we addressed the question if the cerebellar hypoplasia observed in the hyperbilirubinemic Gunn rat co...

  14. Modeling: driving fuel cells

    Directory of Open Access Journals (Sweden)

    Michael Francis


    Fuel cells were invented in 1839 by Sir William Grove, a Welsh judge and gentleman scientist, as a result of his experiments on the electrolysis of water. To put it simply, fuel cells are electrochemical devices that take hydrogen gas from fuel, combine it with oxygen from the air, and generate electricity and heat, with water as the only by-product.

  15. Low in situ expression of antioxidative enzymes in rat cerebellar granular cells susceptible to methylmercury. (United States)

    Fujimura, M; Usuki, F


    Methylmercury (MeHg), an environmental neurotoxicant, induces site-specific toxicity in the brain. Although oxidative stress has been demonstrated with MeHg toxicity, the site-specific toxicity is not completely understood. Among the cerebellar neurons, cerebellar granule cells (CGCs) appear vulnerable to MeHg, whereas Purkinje cells and molecular layer neurons are resistant. Here, we use a MeHg-intoxicated rat model to investigate these cerebellar neurons for the different causes of susceptibility to MeHg. Rats were exposed to 20 ppm MeHg for 4 weeks and subsequently exhibited neuropathological changes in the cerebellum that were similar to those observed in humans. We first isolated the three cerebellar neuron types using a microdissection system and then performed real-time PCR analyses for antioxidative enzymes. We observed that expression of manganese-superoxide dismutase (Mn-SOD), glutathione peroxidase 1 (GPx1), and thioredoxin reductase 1 (TRxR1) was significantly higher in Purkinje cells and molecular layer neurons than in CGCs. Finally, we performed immunohistochemical analyses on the cerebellum. Immunohistochemistry showed increased expression of Mn-SOD, GPx1, and TRxR1 in Purkinje cells and molecular layer neurons, which was coincident with the mRNA expression patterns. Considering Mn-SOD, GPx1, and TRxR1 are critical for protecting cells against MeHg intoxication, the results indicate that low expression of these antioxidative enzymes increases CGCs vulnerability to MeHg toxicity.

  16. Stochastic models of cell motility

    DEFF Research Database (Denmark)

    Gradinaru, Cristian


    Cell motility and migration are central to the development and maintenance of multicellular organisms, and errors during this process can lead to major diseases. Consequently, the mechanisms and phenomenology of cell motility are currently under intense study. In recent years, a new...... interdisciplinary field focusing on the study of biological processes at the nanoscale level, with a range of technological applications in medicine and biological research, has emerged. The work presented in this thesis is at the interface of cell biology, image processing, and stochastic modeling. The stochastic...... models introduced here are based on persistent random motion, which I apply to real-life studies of cell motility on flat and nanostructured surfaces. These models aim to predict the time-dependent position of cell centroids in a stochastic manner, and conversely determine directly from experimental...

  17. A Discrete Cell Migration Model

    Energy Technology Data Exchange (ETDEWEB)

    Nutaro, James J [ORNL; Kruse, Kara L [ORNL; Ward, Richard C [ORNL; O' Quinn, Elizabeth [Wofford College; Woerner, Matthew M [ORNL; Beckerman, Barbara G [ORNL


    Migration of vascular smooth muscle cells is a fundamental process in the development of intimal hyperplasia, a precursor to development of cardiovascular disease and a potential response to injury of an arterial wall. Boyden chamber experiments are used to quantify the motion of cell populations in response to a chemoattractant gradient (i.e., cell chemotaxis). We are developing a mathematical model of cell migration within the Boyden chamber, while simultaneously conducting experiments to obtain parameter values for the migration process. In the future, the model and parameters will be used as building blocks for a detailed model of the process that causes intimal hyperplasia. The cell migration model presented in this paper is based on the notion of a cell as a moving sensor that responds to an evolving chemoattractant gradient. We compare the results of our three-dimensional hybrid model with results from a one-dimensional continuum model. Some preliminary experimental data that is being used to refine the model is also presented.

  18. Simple model of cell crawling

    CERN Document Server

    Ohta, Takao; Sano, Masaki


    Based on symmetry consideration of migration and shape deformations, we formulate phenomenologically the dynamics of cell crawling in two dimensions. Forces are introduced to change the cell shape. The shape deformations induce migration of the cell on a substrate. For time-independent forces we show that not only a stationary motion but also a limit cycle oscillation of the migration velocity and the shape occurs as a result of nonlinear coupling between different deformation modes. Time-dependent forces are generated in a stochastic manner by utilizing the so-called coherence resonance of an excitable system. The present coarse-grained model has a flexibility that it can be applied, e.g., both to keratocyte cells and to Dictyostelium cells, which exhibit quite different dynamics from each other. The key factors for the motile behavior inherent in each cell type are identified in our model.

  19. Simple model of cell crawling (United States)

    Ohta, T.; Tarama, M.; Sano, M.


    Based on symmetry consideration of migration and shape deformations, we formulate phenomenologically the dynamics of cell crawling in two dimensions. Forces are introduced to change the cell shape. The shape deformations induce migration of the cell on a substrate. For time-independent forces we show that not only a stationary motion but also a limit cycle oscillation of the migration velocity and the shape occurs as a result of nonlinear coupling between different deformation modes. Time-dependent forces are generated in a stochastic manner by utilizing the so-called coherence resonance of an excitable system. The present coarse-grained model has a flexibility that it can be applied, e.g., both to keratocyte cells and to Dictyostelium cells, which exhibit quite different dynamics from each other. The key factors for the motile behavior inherent in each cell type are identified in our model.

  20. I(Kr) vs. I(Ks) blockade and arrhythmogenicity in normoxic rabbit Purkinje fibers: does it really make a difference? (United States)

    Puddu, Paolo Emilio; Legrand, Jean-Christophe; Sallé, Laurent; Rouet, René; Ducroq, Joffrey


    The electrophysiological (standard intracellular microelectrode technique) and pro-arrhythmic (occurrence of early after-depolarization) effects of five class III agents acting on delayed rectifier current (I(K)), rapid (I(Kr)), and/or slow (I(Ks)) components have been studied in rabbit Purkinje fibers taken near the septum and submitted in vitro to reduced stimulation rate (from 1 to 0.5 Hz) in the absence or presence of epinephrine (10 nm) during normoxic conditions. There were two I(Kr) blockers (d-sotalol and dofetilide), two I(Ks) blockers (chromanol 293B and HMR 1556), and a non-selective I(K) blocker (azimilide). d-sotalol, dofetilide, and azimilide lengthened APD(60) and APD(90) in a concentration-dependent manner. Both d-sotalol and dofetilide showed pro-arrhythmia at highest concentrations and in the presence of epinephrine and lower stimulation rate. Despite azimilide markedly lengthened APD(90), it was globally less pro-arrhythmic than dofetilide. Thus, in normoxic rabbit Purkinje fibers, I(Kr) blockade prolonged action potential duration (APD) and increased the incidence of early after-depolarizations, particularly so in the presence of adrenergic stimulation and bradycardia, I(Ks) blockade did neither, and non-selective I(K) blockade (by azimilide) behaved principally as I(Kr) blockade. It is concluded that in normoxic rabbit Purkinje fibers, I(Ks) blockade was neutral, whereas I(Kr) blockade was pro-arrhythmic, which may make a difference worth exploration in more complex models.

  1. Cell Fusion along the Anterior-Posterior Neuroaxis in Mice with Experimental Autoimmune Encephalomyelitis.

    Directory of Open Access Journals (Sweden)

    Sreenivasa R Sankavaram

    Full Text Available It is well documented that bone marrow-derived cells can fuse with a diverse range of cells, including brain cells, under normal or pathological conditions. Inflammation leads to robust fusion of bone marrow-derived cells with Purkinje cells and the formation of binucleate heterokaryons in the cerebellum. Heterokaryons form through the fusion of two developmentally differential cells and as a result contain two distinct nuclei without subsequent nuclear or chromosome loss.In the brain, fusion of bone marrow-derived cells appears to be restricted to the complex and large Purkinje cells, raising the question whether the size of the recipient cell is important for cell fusion in the central nervous system. Purkinje cells are among the largest neurons in the central nervous system and accordingly can harbor two nuclei.Using a well-characterized model for heterokaryon formation in the cerebellum (experimental autoimmune encephalomyelitis - a mouse model of multiple sclerosis, we report for the first time that green fluorescent protein-labeled bone marrow-derived cells can fuse and form heterokaryons with spinal cord motor neurons. These spinal cord heterokaryons are predominantly located in or adjacent to an active or previously active inflammation site, demonstrating that inflammation and infiltration of immune cells are key for cell fusion in the central nervous system. While some motor neurons were found to contain two nuclei, co-expressing green fluorescent protein and the neuronal marker, neuron-specific nuclear protein, a number of small interneurons also co-expressed green fluorescent protein and the neuronal marker, neuron-specific nuclear protein. These small heterokaryons were scattered in the gray matter of the spinal cord.This novel finding expands the repertoire of neurons that can form heterokaryons with bone marrow-derived cells in the central nervous system, albeit in low numbers, possibly leading to a novel therapy for spinal cord

  2. Model cell membranes

    DEFF Research Database (Denmark)

    Günther-Pomorski, Thomas; Nylander, Tommy; Cardenas Gomez, Marite


    The high complexity of biological membranes has motivated the development and application of a wide range of model membrane systems to study biochemical and biophysical aspects of membranes in situ under well defined conditions. The aim is to provide fundamental understanding of processes...... controlled by membrane structure, permeability and curvature as well as membrane proteins by using a wide range of biochemical, biophysical and microscopic techniques. This review gives an overview of some currently used model biomembrane systems. We will also discuss some key membrane protein properties...... that are relevant for protein-membrane interactions in terms of protein structure and how it is affected by membrane composition, phase behavior and curvature....

  3. Physical models of cell motility

    CERN Document Server


    This book surveys the most recent advances in physics-inspired cell movement models. This synergetic, cross-disciplinary effort to increase the fidelity of computational algorithms will lead to a better understanding of the complex biomechanics of cell movement, and stimulate progress in research on related active matter systems, from suspensions of bacteria and synthetic swimmers to cell tissues and cytoskeleton.Cell motility and collective motion are among the most important themes in biology and statistical physics of out-of-equilibrium systems, and crucial for morphogenesis, wound healing, and immune response in eukaryotic organisms. It is also relevant for the development of effective treatment strategies for diseases such as cancer, and for the design of bioactive surfaces for cell sorting and manipulation. Substrate-based cell motility is, however, a very complex process as regulatory pathways and physical force generation mechanisms are intertwined. To understand the interplay between adhesion, force ...

  4. Effect of Methamidophos on cerebellar neuronal cells

    African Journals Online (AJOL)


    TH-mediated cerebellar neuronal cell development and function, and consequently could interfere with TH-regulated neuronal ... 1972), decreased number of synapses between the. Purkinje .... 0.008%DNase and triturated in same solution to ...

  5. STD-dependent and independent encoding of input irregularity as spike rate in a computational model of a cerebellar nucleus neuron

    NARCIS (Netherlands)

    J. Luthman (Johannes); F.E. Hoebeek (Freek); R. Maex (Reinoud); N. Davey (Neil); R. Adams (Rod); C.I. de Zeeuw (Chris); V. Steuber (Volker)


    textabstractNeurons in the cerebellar nuclei (CN) receive inhibitory inputs from Purkinje cells in the cerebellar cortex and provide the major output from the cerebellum, but their computational function is not well understood. It has recently been shown that the spike activity of Purkinje cells is

  6. Densità e distribuzione delle cellule di Purkinje nel cervelletto di cane: studio immunoistochimico


    Ruffini, Alessia


    Nella letteratura, gli studi morfologici e morfometrici del cervelletto di animali ed esseri umani, hanno valutato il numero di cellule di Purkinje (CP) solo su alcuni campi a random. Gli studi sono stati spesso condotti su cervelletti fissati in formalina e inclusi in paraffina; gli studi effettuati su campioni congelati sono molto rari. Gli scopi del presente studio sono stati: quantificare il numero e la distribuzione delle CP in tutto il tessuto cerebellare; valutare lo spessore del gr...


    Institute of Scientific and Technical Information of China (English)

    金奇; 沈卫峰; 吴立群


    Long-duration ventricular fibrillation (LDVF) often occurring out-of-hospital has been presented several minutes before electrical shocks. It is important to understand the mechanism by which LDVF is maintained and defibrillated. Purkinje fibers (PFs) have been demonstrated to play a key role in the onset of certain types of ventricular fibrillation. In this review, we discuss the electrophysiological difference between PFs and working myocardium, and the role of the PFs in the maintenance and termination o...

  8. Mathematical Model for Photovoltaic Cells

    Directory of Open Access Journals (Sweden)

    Wafaa ABD EL-BASIT


    Full Text Available The study of photovoltaic systems in an efficient manner requires a precise knowledge of the (I-V and (P-V characteristic curves of photovoltaic modules. So, the aim of the present paper is to estimate such characteristics based on different operating conditions. In this concern, a simple one diode mathematical model was implemented using MATLAB script. The output characteristics of PV cell depend on the environmental conditions. For any solar cell, the model parameters are function of the irradiance and the temperature values of the site where the panel is placed. In this paper, the numerical values of the equivalent circuit parameters are generated by the program. As well, the dependence of the cells electrical parameters are analyzed under the influence of different irradiance and temperature levels. The variation of slopes of the (I–V curves of a cell at short-circuit and open-circuit conditions with intensity of illumination in small span of intensity and different temperature levels have been applied to determine the cell parameters, shunt resistance, series resistance. The results show that the efficiency of solar cells has an inverse relationship with temperature, irradiance levels are affected by the change of the photo-generation current and the series resistance in the single diode model.

  9. Cerebellar Fastigial Nucleus Electrical Stimulation Alleviates Depressive-Like Behaviors in Post-Stroke Depression Rat Model and Potential Mechanisms

    Directory of Open Access Journals (Sweden)

    Lei Zhang


    Full Text Available Objective: To identify the molecular mechanism of post-stroke depression (PSD, and observe the therapeutic effects of cerebellar fastigial nucleus electrical stimulation (FNS on the behaviors and regional cerebral blood flow (rCBF in a PSD rat model. Methods: Healthy SD rats were randomly divided into four groups (sham, stroke, post-stroke depress and FNS group. Sham group (n = 6 underwent sham operation. The other three groups (n = 6*3 underwent MCAO. Rats were examined twice a week in open filed test. Moreover, neuroprotective effect on cerebellar Purkinje cells and expression of cytokines in hippocampal tissue were examined. Results: The PSD group showed a significant weight loss, decreased consumption of sucrose water, reduced rearing and locomotor activities. The FNS significantly alleviates the body weight loss and sucrose preference, locomotor and rearing activities. The bilateral rCBF was also restored after FNS treatment. Moreover, FNS improved the neuroprotection via suppressing apoptosis of cerebellar Purkinje cells. And the inflammatory cytokines mRNA level in hippocampus was significantly decreased. Conclusion: FNS treatment alleviates depressive-like behaviors and rCBF in PSD rats model, which could be attributed to its ability to protect cerebellar Purkinje cells and decrease the mRNA level of inflammatory cytokines.

  10. FGF14 modulates resurgent sodium current in mouse cerebellar Purkinje neurons. (United States)

    Yan, Haidun; Pablo, Juan L; Wang, Chaojian; Pitt, Geoffrey S


    Rapid firing of cerebellar Purkinje neurons is facilitated in part by a voltage-gated Na(+) (NaV) 'resurgent' current, which allows renewed Na(+) influx during membrane repolarization. Resurgent current results from unbinding of a blocking particle that competes with normal channel inactivation. The underlying molecular components contributing to resurgent current have not been fully identified. In this study, we show that the NaV channel auxiliary subunit FGF14 'b' isoform, a locus for inherited spinocerebellar ataxias, controls resurgent current and repetitive firing in Purkinje neurons. FGF14 knockdown biased NaV channels towards the inactivated state by decreasing channel availability, diminishing the 'late' NaV current, and accelerating channel inactivation rate, thereby reducing resurgent current and repetitive spiking. Critical for these effects was both the alternatively spliced FGF14b N-terminus and direct interaction between FGF14b and the NaV C-terminus. Together, these data suggest that the FGF14b N-terminus is a potent regulator of resurgent NaV current in cerebellar Purkinje neurons.

  11. Simulation of Cardiac Arrhythmias Using a 2D Heterogeneous Whole Heart Model. (United States)

    Balakrishnan, Minimol; Chakravarthy, V Srinivasa; Guhathakurta, Soma


    Simulation studies of cardiac arrhythmias at the whole heart level with electrocardiogram (ECG) gives an understanding of how the underlying cell and tissue level changes manifest as rhythm disturbances in the ECG. We present a 2D whole heart model (WHM2D) which can accommodate variations at the cellular level and can generate the ECG waveform. It is shown that, by varying cellular-level parameters like the gap junction conductance (GJC), excitability, action potential duration (APD) and frequency of oscillations of the auto-rhythmic cell in WHM2D a large variety of cardiac arrhythmias can be generated including sinus tachycardia, sinus bradycardia, sinus arrhythmia, sinus pause, junctional rhythm, Wolf Parkinson White syndrome and all types of AV conduction blocks. WHM2D includes key components of the electrical conduction system of the heart like the SA (Sino atrial) node cells, fast conducting intranodal pathways, slow conducting atriovenctricular (AV) node, bundle of His cells, Purkinje network, atrial, and ventricular myocardial cells. SA nodal cells, AV nodal cells, bundle of His cells, and Purkinje cells are represented by the Fitzhugh-Nagumo (FN) model which is a reduced model of the Hodgkin-Huxley neuron model. The atrial and ventricular myocardial cells are modeled by the Aliev-Panfilov (AP) two-variable model proposed for cardiac excitation. WHM2D can prove to be a valuable clinical tool for understanding cardiac arrhythmias.

  12. Garcinia kola aqueous suspension prevents cerebellar neurodegeneration in long-term diabetic rat - a type 1 diabetes mellitus model. (United States)

    Farahna, Mohammed; Seke Etet, Paul F; Osman, Sayed Y; Yurt, Kıymet K; Amir, Naheed; Vecchio, Lorella; Aydin, Isınsu; Aldebasi, Yousef H; Sheikh, Azimullah; Chijuka, John C; Kaplan, Süleyman; Adem, Abdu


    The development of compounds able to improve metabolic syndrome and mitigate complications caused by inappropriate glycemic control in type 1 diabetes mellitus is challenging. The medicinal plant with established hypoglycemic properties Garcinia kola Heckel might have the potential to mitigate diabetes mellitus metabolic syndrome and complications. We have investigated the neuroprotective properties of a suspension of G. kola seeds in long-term type 1 diabetes mellitus rat model. Wistar rats, made diabetic by single injection of streptozotocin were monitored for 8 months. Then, they were administered with distilled water or G. kola oral aqueous suspension daily for 30 days. Body weight and glycemia were determined before and after treatment. After sacrifice, cerebella were dissected out and processed for stereological quantification of Purkinje cells. Histopathological and immunohistochemical analyses of markers of neuroinflammation and neurodegeneration were performed. Purkinje cell counts were significantly increased, and histopathological signs of apoptosis and neuroinflammation decreased, in diabetic animals treated with G. kola compared to diabetic rats given distilled water. Glycemia was also markedly improved and body weight restored to non-diabetic control values, following G. kola treatment. These results suggest that G. kola treatment improved the general condition of long-term diabetic rats and protected Purkinje cells partly by improving the systemic glycemia and mitigating neuroinflammation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  13. PEM Fuel Cells - Fundamentals, Modeling and Applications

    Directory of Open Access Journals (Sweden)

    Maher A.R. Sadiq Al-Baghdadi


    Full Text Available Part I: Fundamentals Chapter 1: Introduction. Chapter 2: PEM fuel cell thermodynamics, electrochemistry, and performance. Chapter 3: PEM fuel cell components. Chapter 4: PEM fuel cell failure modes. Part II: Modeling and Simulation Chapter 5: PEM fuel cell models based on semi-empirical simulation. Chapter 6: PEM fuel cell models based on computational fluid dynamics. Part III: Applications Chapter 7: PEM fuel cell system design and applications.

  14. Demonstration of Purkinje potential during idiopathic left ventricular tachycardia: a marker for ablation site by transient entrainment. (United States)

    Nishizaki, M; Arita, M; Sakurada, H; Ashikaga, T; Yamawake, N; Numano, F; Hiraoka, M


    During VT of QRS morphology with right bundle branch block and left axis deviation in a patient without obvious structural heart disease, entrainment by pacing from the right ventricular outflow tract and high right atrium was demonstrated. During entrainment of VT, a Purkinje potential preceding the QRS and recorded at the left ventricular mid-septum was activated by orthodromic impulses in the reentry circuit. The interval between the Purkinje potential and the earliest left ventricular activation was decrementally prolonged with shortening of pacing cycle length. Radiofrequency energy was applied to this site, resulting in successful elimination of VT. Therefore, the Purkinje potential represented activation by an orthodromic wavefront in the reentry circuit, while the orthodromically distal site to this potential showed an area of slow conduction with decremental property.

  15. Physical models of collective cell motility: from cell to tissue (United States)

    Camley, B. A.; Rappel, W.-J.


    In this article, we review physics-based models of collective cell motility. We discuss a range of techniques at different scales, ranging from models that represent cells as simple self-propelled particles to phase field models that can represent a cell’s shape and dynamics in great detail. We also extensively review the ways in which cells within a tissue choose their direction, the statistics of cell motion, and some simple examples of how cell–cell signaling can interact with collective cell motility. This review also covers in more detail selected recent works on collective cell motion of small numbers of cells on micropatterns, in wound healing, and the chemotaxis of clusters of cells.

  16. Single-cell model of prokaryotic cell cycle. (United States)

    Abner, Kristo; Aaviksaar, Tõnis; Adamberg, Kaarel; Vilu, Raivo


    One of the recognized prokaryotic cell cycle theories is Cooper-Helmstetter (CH) theory which relates start of DNA replication to particular (initiation) cell mass, cell growth and division. Different aspects of this theory have been extensively studied in the past. In the present study CH theory was applied at single cell level. Universal equations were derived for different cell parameters (cell mass and volume, surface area, DNA amount and content) depending on constructivist cell cycle parameters (unit mass, replication and division times, cell age, cell cycle duration) based on selected growth laws of cell mass (linear, exponential). The equations derived can be integrated into single-cell models for the analysis and design of bacterial cells. © 2013 Published by Elsevier Ltd.

  17. Modeling Rett Syndrome with Stem Cells


    Walsh, Ryan M.; Hochedlinger, Konrad


    The discovery that somatic cells can be reprogrammed into induced pluripotent stem cells (iPSCs) raised the exciting possibility of modeling diseases with patient-specific cells. Marchetto et al. (2010) now use iPSC technology to generate, characterize, and treat an in vitro model for the autism spectrum disorder, Rett syndrome.

  18. Cell Division in the Light of Modeling. (United States)

    Bellaïche, Yohanns


    Theoretical modeling is central to elucidating underlying principles of emergent properties of complex systems. In cell and developmental biology, the last 15 years have witnessed a convergence of empirical and modeling approaches for fresh perspectives. The role of cell division in coordinating size, shape, and fate in particular illustrates the ever-growing impact of modeling.

  19. Long-term potentiation of inhibitory synaptic transmission onto cerebellar Purkinje neurons contributes to adaptation of vestibulo-ocular reflex. (United States)

    Tanaka, Shinsuke; Kawaguchi, Shin-Ya; Shioi, Go; Hirano, Tomoo


    Synaptic plasticity in the cerebellum is thought to contribute to motor learning. In particular, long-term depression (LTD) at parallel fiber (PF) to Purkinje neuron (PN) excitatory synapses has attracted much attention of neuroscientists as a primary cellular mechanism for motor learning. In contrast, roles of plasticity at cerebellar inhibitory synapses in vivo remain unknown. Here, we have investigated the roles of long-lasting enhancement of transmission at GABAergic synapses on a PN that is known as rebound potentiation (RP). Previous studies demonstrated that binding of GABAA receptor with GABAA receptor-associated protein (GABARAP) is required for RP, and that a peptide that blocks this binding suppresses RP induction. To address the functional roles of RP, we generated transgenic mice that express this peptide fused to a fluorescent protein selectively in PNs using the PN-specific L7 promoter. These mice failed to show RP, although they showed no changes in the basal amplitude or frequency of miniature IPSCs. The transgenic mice also showed no abnormality in gross cerebellar morphology, LTD, or other excitatory synaptic properties, or intrinsic excitability of PNs. Next, we attempted to evaluate their motor control and learning ability by examining reflex eye movements. The basal dynamic properties of the vestibulo-ocular reflex and optokinetic response, and adaptation of the latter, were normal in the transgenic mice. In contrast, the transgenic mice showed defects in the adaptation of vestibulo-ocular reflex, a model paradigm of cerebellum-dependent motor learning. These results together suggest that RP contributes to a certain type of motor learning.

  20. Adaptive Mesh Refinement and Adaptive Time Integration for Electrical Wave Propagation on the Purkinje System

    Directory of Open Access Journals (Sweden)

    Wenjun Ying


    Full Text Available A both space and time adaptive algorithm is presented for simulating electrical wave propagation in the Purkinje system of the heart. The equations governing the distribution of electric potential over the system are solved in time with the method of lines. At each timestep, by an operator splitting technique, the space-dependent but linear diffusion part and the nonlinear but space-independent reactions part in the partial differential equations are integrated separately with implicit schemes, which have better stability and allow larger timesteps than explicit ones. The linear diffusion equation on each edge of the system is spatially discretized with the continuous piecewise linear finite element method. The adaptive algorithm can automatically recognize when and where the electrical wave starts to leave or enter the computational domain due to external current/voltage stimulation, self-excitation, or local change of membrane properties. Numerical examples demonstrating efficiency and accuracy of the adaptive algorithm are presented.

  1. Modeling the Shapes of Cells (United States)

    Garimella, Umadevi I.; Robertson, Belinda M.


    A solid understanding of the structure and function of cells can help establish the foundation for learning advanced concepts in the biological sciences. The concept of the cell is introduced in middle school life science courses and is continued at the undergraduate level in college (NRC 2012; Reece et al. 2014). Cells are introduced to students…

  2. Modeling the Shapes of Cells (United States)

    Garimella, Umadevi I.; Robertson, Belinda M.


    A solid understanding of the structure and function of cells can help establish the foundation for learning advanced concepts in the biological sciences. The concept of the cell is introduced in middle school life science courses and is continued at the undergraduate level in college (NRC 2012; Reece et al. 2014). Cells are introduced to students…

  3. Memory B cells in mouse models. (United States)

    Bergmann, B; Grimsholm, O; Thorarinsdottir, K; Ren, W; Jirholt, P; Gjertsson, I; Mårtensson, I-L


    One of the principles behind vaccination, as shown by Edward Jenner in 1796, and host protection is immunological memory, and one of the cells central to this is the antigen-experienced memory B cell that responds rapidly upon re-exposure to the initiating antigen. Classically, memory B cells have been defined as progenies of germinal centre (GC) B cells expressing isotype-switched and substantially mutated B cell receptors (BCRs), that is, membrane-bound antibodies. However, it has become apparent over the last decade that this is not the only pathway to B cell memory. Here, we will discuss memory B cells in mice, as defined by (1) cell surface markers; (2) multiple layers; (3) formation in a T cell-dependent and either GC-dependent or GC-independent manner; (4) formation in a T cell-independent fashion. Lastly, we will touch upon memory B cells in; (5) mouse models of autoimmune diseases.

  4. The effects of low concentrations of cardiotonic steroids on membrane currents and tension in sheep Purkinje fibres. (United States)

    Hart, G; Noble, D; Shimoni, Y


    lengthening of the action potential duration. Positive inotropy and action potential shortening occurred with higher doses.10. A computer model of ionic currents and distributions in Purkinje fibres satisfactorily reproduced the changes in membrane currents and ionic gradients observed with cardiotonic steroids. The only perturbations capable of explaining our results were Na pump stimulation and inhibition.11. It is concluded that cardiotonic steroids possess two inotropic mechanisms. The first is a low-dose positive inotropic mechanism causally unrelated to changes in sodium pump activity and possibly a direct release of a membrane-associated calcium fraction. Should this mechanism be unavailable then net pump stimulation at low doses will produce negative inotropy. The second mechanism is the well known Na-lag process.

  5. Evolving Models of Pavlovian Conditioning : Cerebellar Cortical Dynamics in Awake Behaving Mice

    NARCIS (Netherlands)

    Ten Brinke, Michiel M; Boele, Henk-Jan; Spanke, Jochen K; Potters, Jan-Willem; Kornysheva, Katja; Wulff, Peer; IJpelaar, Anna C H G; Koekkoek, Sebastiaan K E; De Zeeuw, Chris I


    Three decades of electrophysiological research on cerebellar cortical activity underlying Pavlovian conditioning have expanded our understanding of motor learning in the brain. Purkinje cell simple spike suppression is considered to be crucial in the expression of conditional blink responses (CRs).

  6. Stochastic Gompertz model of tumour cell growth. (United States)

    Lo, C F


    In this communication, based upon the deterministic Gompertz law of cell growth, a stochastic model in tumour growth is proposed. This model takes account of both cell fission and mortality too. The corresponding density function of the size of the tumour cells obeys a functional Fokker--Planck equation which can be solved analytically. It is found that the density function exhibits an interesting "multi-peak" structure generated by cell fission as time evolves. Within this framework the action of therapy is also examined by simply incorporating a therapy term into the deterministic cell growth term.

  7. Active Gel Model of Amoeboid Cell Motility

    CERN Document Server

    Callan-Jones, A C


    We develop a model of amoeboid cell motility based on active gel theory. Modeling the motile apparatus of a eukaryotic cell as a confined layer of finite length of poroelastic active gel permeated by a solvent, we first show that, due to active stress and gel turnover, an initially static and homogeneous layer can undergo a contractile-type instability to a polarized moving state in which the rear is enriched in gel polymer. This agrees qualitatively with motile cells containing an actomyosin-rich uropod at their rear. We find that the gel layer settles into a steadily moving, inhomogeneous state at long times, sustained by a balance between contractility and filament turnover. In addition, our model predicts an optimal value of the gel-susbstrate adhesion leading to maximum layer speed, in agreement with cell motility assays. The model may be relevant to motility of cells translocating in complex, confining environments that can be mimicked experimentally by cell migration through microchannels.

  8. Mathematical model of electrotaxis in osteoblastic cells

    NARCIS (Netherlands)

    Vanegas-Acosta, J.C.; Garzón-Alvarado, D.A.; Zwamborn, A.P.M.


    Electrotaxis is the cell migration in the presence of an electric field (EF). This migration is parallel to the EF vector and overrides chemical migration cues. In this paper we introduce a mathematical model for the electrotaxis in osteoblastic cells. The model is evaluated using different EF stren

  9. The first knockin mouse model of episodic ataxia type 2. (United States)

    Rose, Samuel J; Kriener, Lisa H; Heinzer, Ann K; Fan, Xueliang; Raike, Robert S; van den Maagdenberg, Arn M J M; Hess, Ellen J


    Episodic ataxia type 2 (EA2) is an autosomal dominant disorder associated with attacks of ataxia that are typically precipitated by stress, ethanol, caffeine or exercise. EA2 is caused by loss-of-function mutations in the CACNA1A gene, which encodes the α1A subunit of the CaV2.1 voltage-gated Ca(2+) channel. To better understand the pathomechanisms of this disorder in vivo, we created the first genetic animal model of EA2 by engineering a mouse line carrying the EA2-causing c.4486T>G (p.F1406C) missense mutation in the orthologous mouse Cacna1a gene. Mice homozygous for the mutated allele exhibit a ~70% reduction in CaV2.1 current density in Purkinje cells, though surprisingly do not exhibit an overt motor phenotype. Mice hemizygous for the knockin allele (EA2/- mice) did exhibit motor dysfunction measurable by rotarod and pole test. Studies using Cre-flox conditional genetics explored the role of cerebellar Purkinje cells or cerebellar granule cells in the poor motor performance of EA2/- mice and demonstrate that manipulation of either cell type alone did not cause poor motor performance. Thus, it is possible that subtle dysfunction arising from multiple cell types is necessary for the expression of certain ataxia syndromes. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Malaria modeling: In vitro stem cells vs in vivo models

    Institute of Scientific and Technical Information of China (English)

    Florian; Noulin


    The recent development of stem cell research and the possibility of generating cells that can be stably and permanently modified in their genome open a broad horizon in the world of in vitro modeling. The malaria field is gaining new opportunities from this importantbreakthrough and novel tools were adapted and opened new frontiers for malaria research. In addition to the new in vitro systems, in recent years there were also significant advances in the development of new animal models that allows studying the entire cell cycle of human malaria. In this paper, we review the different protocols available to study human Plasmodium species either by using stem cell or alternative animal models.

  11. Malaria modeling: In vitro stem cells vs in vivo models. (United States)

    Noulin, Florian


    The recent development of stem cell research and the possibility of generating cells that can be stably and permanently modified in their genome open a broad horizon in the world of in vitro modeling. The malaria field is gaining new opportunities from this important breakthrough and novel tools were adapted and opened new frontiers for malaria research. In addition to the new in vitro systems, in recent years there were also significant advances in the development of new animal models that allows studying the entire cell cycle of human malaria. In this paper, we review the different protocols available to study human Plasmodium species either by using stem cell or alternative animal models.

  12. Cytoview: Development of a cell modelling framework

    Indian Academy of Sciences (India)

    Prashant Khodade; Samta Malhotra; Nirmal Kumar; M Sriram Iyengar; N Balakrishnan; Nagasuma Chandra


    The biological cell, a natural self-contained unit of prime biological importance, is an enormously complex machine that can be understood at many levels. A higher-level perspective of the entire cell requires integration of various features into coherent, biologically meaningful descriptions. There are some efforts to model cells based on their genome, proteome or metabolome descriptions. However, there are no established methods as yet to describe cell morphologies, capture similarities and differences between different cells or between healthy and disease states. Here we report a framework to model various aspects of a cell and integrate knowledge encoded at different levels of abstraction, with cell morphologies at one end to atomic structures at the other. The different issues that have been addressed are ontologies, feature description and model building. The framework describes dotted representations and tree data structures to integrate diverse pieces of data and parametric models enabling size, shape and location descriptions. The framework serves as a first step in integrating different levels of data available for a biological cell and has the potential to lead to development of computational models in our pursuit to model cell structure and function, from which several applications can flow out.

  13. Stochastic biophysical modeling of irradiated cells

    CERN Document Server

    Fornalski, Krzysztof Wojciech


    The paper presents a computational stochastic model of virtual cells irradiation, based on Quasi-Markov Chain Monte Carlo method and using biophysical input. The model is based on a stochastic tree of probabilities for each cell of the entire colony. Biophysics of the cells is described by probabilities and probability distributions provided as the input. The adaptation of nucleation and catastrophe theories, well known in physics, yields sigmoidal relationships for carcinogenic risk as a function of the irradiation. Adaptive response and bystander effect, incorporated into the model, improves its application. The results show that behavior of virtual cells can be successfully modeled, e.g. cancer transformation, creation of mutations, radioadaptation or radiotherapy. The used methodology makes the model universal and practical for simulations of general processes. Potential biophysical curves and relationships are also widely discussed in the paper. However, the presented theoretical model does not describe ...

  14. Retinal Cell Degeneration in Animal Models


    Masayuki Niwa; Hitomi Aoki; Akihiro Hirata; Hiroyuki Tomita; Green, Paul G.; Akira Hara


    The aim of this review is to provide an overview of various retinal cell degeneration models in animal induced by chemicals (N-methyl-d-aspartate- and CoCl2-induced), autoimmune (experimental autoimmune encephalomyelitis), mechanical stress (optic nerve crush-induced, light-induced) and ischemia (transient retinal ischemia-induced). The target regions, pathology and proposed mechanism of each model are described in a comparative fashion. Animal models of retinal cell degeneration provide insi...

  15. Mathematical modeling of polymer electrolyte fuel cells (United States)

    Sousa, Ruy; Gonzalez, Ernesto R.

    Fuel cells with a polymer electrolyte membrane have been receiving more and more attention. Modeling plays an important role in the development of fuel cells. In this paper, the state-of-the-art regarding modeling of fuel cells with a polymer electrolyte membrane is reviewed. Modeling has allowed detailed studies concerning the development of these cells, e.g. in discussing the electrocatalysis of the reactions and the design of water-management schemes to cope with membrane dehydration. Two-dimensional models have been used to represent reality, but three-dimensional models can cope with some important additional aspects. Consideration of two-phase transport in the air cathode of a proton exchange membrane fuel cell seems to be very appropriate. Most fuel cells use hydrogen as a fuel. Besides safety concerns, there are problems associated with production, storage and distribution of this fuel. Methanol, as a liquid fuel, can be the solution to these problems and direct methanol fuel cells (DMFCs) are attractive for several applications. Mass transport is a factor that may limit the performance of the cell. Adsorption steps may be coupled to Tafel kinetics to describe methanol oxidation and methanol crossover must also be taken into account. Extending the two-phase approach to the DMFC modeling is a recent, important point.

  16. Modeled changes of cerebellar activity in mutant mice are predictive of their learning impairments (United States)

    Badura, Aleksandra; Clopath, Claudia; Schonewille, Martijn; de Zeeuw, Chris I.


    Translating neuronal activity to measurable behavioral changes has been a long-standing goal of systems neuroscience. Recently, we have developed a model of phase-reversal learning of the vestibulo-ocular reflex, a well-established, cerebellar-dependent task. The model, comprising both the cerebellar cortex and vestibular nuclei, reproduces behavioral data and accounts for the changes in neural activity during learning in wild type mice. Here, we used our model to predict Purkinje cell spiking as well as behavior before and after learning of five different lines of mutant mice with distinct cell-specific alterations of the cerebellar cortical circuitry. We tested these predictions by obtaining electrophysiological data depicting changes in neuronal spiking. We show that our data is largely consistent with the model predictions for simple spike modulation of Purkinje cells and concomitant behavioral learning in four of the mutants. In addition, our model accurately predicts a shift in simple spike activity in a mutant mouse with a brainstem specific mutation. This combination of electrophysiological and computational techniques opens a possibility of predicting behavioral impairments from neural activity.

  17. Modeling cell behavior: moving beyond intuition

    Directory of Open Access Journals (Sweden)

    Mario Jolicoeur


    Full Text Available In the context of the launching of this new journal, we propose a forum to the community of researchers interested and involved in, or even simply questioning the why, what, how, and when of modeling cell or cell culture behavior. To start the discussion, we review some of the usual questions we are routinely asked on the pertinence of modeling cell behavior, and on who might benefit from conducting such work. To draw a global portrait, throughout this text we refer the reader to handbooks introducing the basics of modeling a biosystem, as well as to selected works that can help visualize the broad fields of applications.

  18. Modelling of Mammalian cells and cell culture processes. (United States)

    Sidoli, F R; Mantalaris, A; Asprey, S P


    Mammalian cell cultures represent the major source for a number of very high-value biopharmaceutical products, including monoclonal antibodies (MAbs), viral vaccines, and hormones. These products are produced in relatively small quantities due to the highly specialised culture conditions and their susceptibility to either reduced productivity or cell death as a result of slight deviations in the culture conditions. The use of mathematical relationships to characterise distinct parts of the physiological behaviour of mammalian cells and the systematic integration of this information into a coherent, predictive model, which can be used for simulation, optimisation, and control purposes would contribute to efforts to increase productivity and control product quality. Models can also aid in the understanding and elucidation of underlying mechanisms and highlight the lack of accuracy or descriptive ability in parts of the model where experimental and simulated data cannot be reconciled. This paper reviews developments in the modelling of mammalian cell cultures in the last decade and proposes a future direction - the incorporation of genomic, proteomic, and metabolomic data, taking advantage of recent developments in these disciplines and thus improving model fidelity. Furthermore, with mammalian cell technology dependent on experiments for information, model-based experiment design is formally introduced, which when applied can result in the acquisition of more informative data from fewer experiments. This represents only part of a broader framework for model building and validation, which consists of three distinct stages: theoretical model assessment, model discrimination, and model precision, which provides a systematic strategy from assessing the identifiability and distinguishability of a set of competing models to improving the parameter precision of a final validated model.

  19. On a poroviscoelastic model for cell crawling. (United States)

    Kimpton, L S; Whiteley, J P; Waters, S L; Oliver, J M


    In this paper a minimal, one-dimensional, two-phase, viscoelastic, reactive, flow model for a crawling cell is presented. Two-phase models are used with a variety of constitutive assumptions in the literature to model cell motility. We use an upper-convected Maxwell model and demonstrate that even the simplest of two-phase, viscoelastic models displays features relevant to cell motility. We also show care must be exercised in choosing parameters for such models as a poor choice can lead to an ill-posed problem. A stability analysis reveals that the initially stationary, spatially uniform strip of cytoplasm starts to crawl in response to a perturbation which breaks the symmetry of the network volume fraction or network stress. We also demonstrate numerically that there is a steady travelling-wave solution in which the crawling velocity has a bell-shaped dependence on adhesion strength, in agreement with biological observation.

  20. On a poroviscoelastic model for cell crawling

    KAUST Repository

    Kimpton, L. S.


    In this paper a minimal, one-dimensional, two-phase, viscoelastic, reactive, flow model for a crawling cell is presented. Two-phase models are used with a variety of constitutive assumptions in the literature to model cell motility. We use an upper-convected Maxwell model and demonstrate that even the simplest of two-phase, viscoelastic models displays features relevant to cell motility. We also show care must be exercised in choosing parameters for such models as a poor choice can lead to an ill-posed problem. A stability analysis reveals that the initially stationary, spatially uniform strip of cytoplasm starts to crawl in response to a perturbation which breaks the symmetry of the network volume fraction or network stress. We also demonstrate numerically that there is a steady travelling-wave solution in which the crawling velocity has a bell-shaped dependence on adhesion strength, in agreement with biological observation.

  1. A Structured Population Model of Cell Differentiation

    CERN Document Server

    Doumic, Marie; Perthame, Benoit; Zubelli, Jorge P


    We introduce and analyze several aspects of a new model for cell differentiation. It assumes that differentiation of progenitor cells is a continuous process. From the mathematical point of view, it is based on partial differential equations of transport type. Specifically, it consists of a structured population equation with a nonlinear feedback loop. This models the signaling process due to cytokines, which regulate the differentiation and proliferation process. We compare the continuous model to its discrete counterpart, a multi-compartmental model of a discrete collection of cell subpopulations recently proposed by Marciniak-Czochra et al. in 2009 to investigate the dynamics of the hematopoietic system. We obtain uniform bounds for the solutions, characterize steady state solutions, and analyze their linearized stability. We show how persistence or extinction might occur according to values of parameters that characterize the stem cells self-renewal. We also perform numerical simulations and discuss the q...

  2. Spatial Modeling Tools for Cell Biology (United States)


    34 iv Figure 5.1: Computational results for a diffusion problem on planar square thin film............ 36 Figure 5.2... Wisc . Open Microscopy Env. Pre-CoBi Model Lib. CFDRC CoBi Tools CFDRC CoBi Tools Simulation Environment JigCell Tools Figure 4.1: Cell biology

  3. Mathematical model of electrotaxis in osteoblastic cells. (United States)

    Vanegas-Acosta, J C; Garzón-Alvarado, D A; Zwamborn, A P M


    Electrotaxis is the cell migration in the presence of an electric field (EF). This migration is parallel to the EF vector and overrides chemical migration cues. In this paper we introduce a mathematical model for the electrotaxis in osteoblastic cells. The model is evaluated using different EF strengths and different configurations of both electrical and chemical stimuli. Accordingly, we found that the cell migration speed is described as the combination of an electrical and a chemical term. Cell migration is faster when both stimuli orient cell migration towards the same direction. In contrast, a reduced speed is obtained when the EF vector is opposed to the direction of the chemical stimulus. Numerical relations were obtained to quantify the cell migration speed at each configuration. Additional calculations for the cell colonization of a substrate also show mediation of the EF strength. Therefore, the term electro-osteoconduction is introduced to account the electrically induced cell colonization. Since numerical results compare favorably with experimental evidence, the model is suitable to be extended to other types of cells, and to numerically explore the influence of EF during wound healing. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Computational and Modeling Strategies for Cell Motility (United States)

    Wang, Qi; Yang, Xiaofeng; Adalsteinsson, David; Elston, Timothy C.; Jacobson, Ken; Kapustina, Maryna; Forest, M. Gregory

    A predictive simulation of the dynamics of a living cell remains a fundamental modeling and computational challenge. The challenge does not even make sense unless one specifies the level of detail and the phenomena of interest, whether the focus is on near-equilibrium or strongly nonequilibrium behavior, and on localized, subcellular, or global cell behavior. Therefore, choices have to be made clear at the outset, ranging from distinguishing between prokaryotic and eukaryotic cells, specificity within each of these types, whether the cell is "normal," whether one wants to model mitosis, blebs, migration, division, deformation due to confined flow as with red blood cells, and the level of microscopic detail for any of these processes. The review article by Hoffman and Crocker [48] is both an excellent overview of cell mechanics and an inspiration for our approach. One might be interested, for example, in duplicating the intricate experimental details reported in [43]: "actin polymerization periodically builds a mechanical link, the lamellipodium, connecting myosin motors with the initiation of adhesion sites, suggesting that the major functions driving motility are coordinated by a biomechanical process," or to duplicate experimental evidence of traveling waves in cells recovering from actin depolymerization [42, 35]. Modeling studies of lamellipodial structure, protrusion, and retraction behavior range from early mechanistic models [84] to more recent deterministic [112, 97] and stochastic [51] approaches with significant biochemical and structural detail. Recent microscopic-macroscopic models and algorithms for cell blebbing have been developed by Young and Mitran [116], which update cytoskeletal microstructure via statistical sampling techniques together with fluid variables. Alternatively, whole cell compartment models (without spatial details) of oscillations in spreading cells have been proposed [35, 92, 109] which show positive and negative feedback

  5. Mathematical model of a cell size checkpoint.

    Directory of Open Access Journals (Sweden)

    Marco Vilela

    Full Text Available How cells regulate their size from one generation to the next has remained an enigma for decades. Recently, a molecular mechanism that links cell size and cell cycle was proposed in fission yeast. This mechanism involves changes in the spatial cellular distribution of two proteins, Pom1 and Cdr2, as the cell grows. Pom1 inhibits Cdr2 while Cdr2 promotes the G2 → M transition. Cdr2 is localized in the middle cell region (midcell whereas the concentration of Pom1 is highest at the cell tips and declines towards the midcell. In short cells, Pom1 efficiently inhibits Cdr2. However, as cells grow, the Pom1 concentration at midcell decreases such that Cdr2 becomes activated at some critical size. In this study, the chemistry of Pom1 and Cdr2 was modeled using a deterministic reaction-diffusion-convection system interacting with a deterministic model describing microtubule dynamics. Simulations mimicked experimental data from wild-type (WT fission yeast growing at normal and reduced rates; they also mimicked the behavior of a Pom1 overexpression mutant and WT yeast exposed to a microtubule depolymerizing drug. A mechanism linking cell size and cell cycle, involving the downstream action of Cdr2 on Wee1 phosphorylation, is proposed.

  6. Malaria modeling: In vitro stem cells vs in vivo models


    Noulin, Florian


    The recent development of stem cell research and the possibility of generating cells that can be stably and permanently modified in their genome open a broad horizon in the world of in vitro modeling. The malaria field is gaining new opportunities from this important breakthrough and novel tools were adapted and opened new frontiers for malaria research. In addition to the new in vitro systems, in recent years there were also significant advances in the development of new animal models that a...

  7. Effects of thallium on membrane currents at diastolic potentials in canine cardiac Purkinje strands. (United States)

    Cohen, I S; Mulrine, N K


    A two-micro-electrode voltage-clamp technique was used to record membrane currents from canine cardiac Purkinje strands during hyperpolarizing steps to potentials between -70 and -150 mV in Tyrode solutions containing K+ and/or Tl+. Complete replacement of external K+ by equimolar Tl+ increases the instantaneous inwardly rectifying current. The inwardly rectifying region of the instantaneous I-V relation is shifted to more positive potentials and its slope is increased. The diastolic time-dependent current is reduced or reversed. Partial substitution of equimolar Tl+ for K+ reduces the diastolic time-dependent current. The instantaneous I-V relation is shifted inward for molar fractions of Tl+ (YTl) greater than 0.5, and is slightly more inward or unchanged for YTl less than or equal to 0.5. Addition of small amounts of Tl+ shifts the instantaneous I-V relation inward and reduces the diastolic time-dependent current. Addition of Tl+ in solutions containing Ba2+ to block the background inward rectifier has no effect on the instantaneous I-V relation; the diastolic time-dependent (pace-maker) current is reduced. Block of the pace-maker current by Tl+ is largely independent of potential in Ba2+ Tyrode solution. Since Tl+ has opposite effects on the pace-maker current and the inward rectifier, these findings support other evidence that the pace-maker current is not part of the background inward rectifier.

  8. Challenges in structural approaches to cell modeling. (United States)

    Im, Wonpil; Liang, Jie; Olson, Arthur; Zhou, Huan-Xiang; Vajda, Sandor; Vakser, Ilya A


    Computational modeling is essential for structural characterization of biomolecular mechanisms across the broad spectrum of scales. Adequate understanding of biomolecular mechanisms inherently involves our ability to model them. Structural modeling of individual biomolecules and their interactions has been rapidly progressing. However, in terms of the broader picture, the focus is shifting toward larger systems, up to the level of a cell. Such modeling involves a more dynamic and realistic representation of the interactomes in vivo, in a crowded cellular environment, as well as membranes and membrane proteins, and other cellular components. Structural modeling of a cell complements computational approaches to cellular mechanisms based on differential equations, graph models, and other techniques to model biological networks, imaging data, etc. Structural modeling along with other computational and experimental approaches will provide a fundamental understanding of life at the molecular level and lead to important applications to biology and medicine. A cross section of diverse approaches presented in this review illustrates the developing shift from the structural modeling of individual molecules to that of cell biology. Studies in several related areas are covered: biological networks; automated construction of three-dimensional cell models using experimental data; modeling of protein complexes; prediction of non-specific and transient protein interactions; thermodynamic and kinetic effects of crowding; cellular membrane modeling; and modeling of chromosomes. The review presents an expert opinion on the current state-of-the-art in these various aspects of structural modeling in cellular biology, and the prospects of future developments in this emerging field. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. An electrostatic model for biological cell division

    CERN Document Server

    Faraggi, Eshel


    Probably the most fundamental processes for biological systems is their ability to create themselves through the use of cell division and cell differentiation. In this work a simple physical model is proposed for biological cell division. The model consists of a positive ionic gradient across the cell membrane, and concentration of charge at the nodes of the spindle and on the chromosomes. A simple calculation, based on Coulomb's Law, shows that under such circumstances a chromosome will tend to break up to its constituent chromatids and that the chromatids will be separated by a distance that is an order of thirty percent of the distance between the spindle nodes. Further repulsion between the nodes will tend to stretch the cell and eventually break the cell membrane between the separated chromatids, leading to cell division. The importance of this work is in continuing the understanding of the electromagnetic basis of cell division and providing it with an analytical model. A central implication of this and...

  10. Large animal models for stem cell therapy. (United States)

    Harding, John; Roberts, R Michael; Mirochnitchenko, Oleg


    The field of regenerative medicine is approaching translation to clinical practice, and significant safety concerns and knowledge gaps have become clear as clinical practitioners are considering the potential risks and benefits of cell-based therapy. It is necessary to understand the full spectrum of stem cell actions and preclinical evidence for safety and therapeutic efficacy. The role of animal models for gaining this information has increased substantially. There is an urgent need for novel animal models to expand the range of current studies, most of which have been conducted in rodents. Extant models are providing important information but have limitations for a variety of disease categories and can have different size and physiology relative to humans. These differences can preclude the ability to reproduce the results of animal-based preclinical studies in human trials. Larger animal species, such as rabbits, dogs, pigs, sheep, goats, and non-human primates, are better predictors of responses in humans than are rodents, but in each case it will be necessary to choose the best model for a specific application. There is a wide spectrum of potential stem cell-based products that can be used for regenerative medicine, including embryonic and induced pluripotent stem cells, somatic stem cells, and differentiated cellular progeny. The state of knowledge and availability of these cells from large animals vary among species. In most cases, significant effort is required for establishing and characterizing cell lines, comparing behavior to human analogs, and testing potential applications. Stem cell-based therapies present significant safety challenges, which cannot be addressed by traditional procedures and require the development of new protocols and test systems, for which the rigorous use of larger animal species more closely resembling human behavior will be required. In this article, we discuss the current status and challenges of and several major directions

  11. A differential model of the complex cell. (United States)

    Hansard, Miles; Horaud, Radu


    The receptive fields of simple cells in the visual cortex can be understood as linear filters. These filters can be modeled by Gabor functions or gaussian derivatives. Gabor functions can also be combined in an energy model of the complex cell response. This letter proposes an alternative model of the complex cell, based on gaussian derivatives. It is most important to account for the insensitivity of the complex response to small shifts of the image. The new model uses a linear combination of the first few derivative filters, at a single position, to approximate the first derivative filter, at a series of adjacent positions. The maximum response, over all positions, gives a signal that is insensitive to small shifts of the image. This model, unlike previous approaches, is based on the scale space theory of visual processing. In particular, the complex cell is built from filters that respond to the 2D differential structure of the image. The computational aspects of the new model are studied in one and two dimensions, using the steerability of the gaussian derivatives. The response of the model to basic images, such as edges and gratings, is derived formally. The response to natural images is also evaluated, using statistical measures of shift insensitivity. The neural implementation and predictions of the model are discussed.

  12. Cardiac Electromechanical Models: From Cell to Organ

    Directory of Open Access Journals (Sweden)

    Natalia A Trayanova


    Full Text Available The heart is a multiphysics and multiscale system that has driven the development of the most sophisticated mathematical models at the frontiers of computation physiology and medicine. This review focuses on electromechanical (EM models of the heart from the molecular level of myofilaments to anatomical models of the organ. Because of the coupling in terms of function and emergent behaviors at each level of biological hierarchy, separation of behaviors at a given scale is difficult. Here, a separation is drawn at the cell level so that the first half addresses subcellular/single cell models and the second half addresses organ models. At the subcelluar level, myofilament models represent actin-myosin interaction and Ca-based activation. Myofilament models and their refinements represent an overview of the development in the field. The discussion of specific models emphasizes the roles of cooperative mechanisms and sarcomere length dependence of contraction force, considered the cellular basis of the Frank-Starling law. A model of electrophysiology and Ca handling can be coupled to a myofilament model to produce an EM cell model, and representative examples are summarized to provide an overview of the progression of field. The second half of the review covers organ-level models that require solution of the electrical component as a reaction-diffusion system and the mechanical component, in which active tension generated by the myocytes produces deformation of the organ as described by the equations of continuum mechanics. As outlined in the review, different organ-level models have chosen to use different ionic and myofilament models depending on the specific application; this choice has been largely dictated by compromises between model complexity and computational tractability. The review also addresses application areas of EM models such as cardiac resynchronization therapy and the role of mechano-electric coupling in arrhythmias and

  13. Study of Photovoltaic Cells Engineering Mathematical Model (United States)

    Zhou, Jun; Yu, Zhengping; Lu, Zhengyi; Li, Chenhui; Zhang, Ruilan


    The characteristic curve of photovoltaic cells is the theoretical basis of PV Power, which simplifies the existing mathematical model, eventually, obtains a mathematical model used in engineering. The characteristic curve of photovoltaic cells contains both exponential and logarithmic calculation. The exponential and logarithmic spread out through Taylor series, which includes only four arithmetic and use single chip microcontroller as the control center. The result shows that: the use of single chip microcontroller for calculating exponential and logarithmic functions, simplifies mathematical model of PV curve, also can meet the specific conditions’ requirement for engineering applications.

  14. Engineered Models of Confined Cell Migration (United States)

    Paul, Colin D.; Hung, Wei-Chien; Wirtz, Denis; Konstantopoulos, Konstantinos


    Cells in the body are physically confined by neighboring cells, tissues, and the extracellular matrix. Although physical confinement modulates intracellular signaling and the underlying mechanisms of cell migration, it is difficult to study in vivo. Furthermore, traditional two-dimensional cell migration assays do not recapitulate the complex topographies found in the body. Therefore, a number of experimental in vitro models that confine and impose forces on cells in well-defined microenvironments have been engineered. We describe the design and use of microfluidic microchannel devices, grooved substrates, micropatterned lines, vertical confinement devices, patterned hydrogels, and micropipette aspiration assays for studying cell responses to confinement. Use of these devices has enabled the delineation of changes in cytoskeletal reorganization, cell–substrate adhesions, intracellular signaling, nuclear shape, and gene expression that result from physical confinement. These assays and the physiologically relevant signaling pathways that have been elucidated are beginning to have a translational and clinical impact. PMID:27420571

  15. Modeling Natural Killer Cell Targeted Immunotherapies (United States)

    Lopez-Lastra, Silvia; Di Santo, James P.


    Animal models have extensively contributed to our understanding of human immunobiology and to uncover the underlying pathological mechanisms occurring in the development of diseases. However, mouse models do not reproduce the genetic and molecular complexity inherent in human disease conditions. Human immune system (HIS) mouse models that are susceptible to human pathogens and can recapitulate human hematopoiesis and tumor immunobiology provide one means to bridge the interspecies gap. Natural killer cells are the founding member of the innate lymphoid cell family. They exert a rapid and strong immune response against tumor and pathogen-infected cells. Their antitumor features have long been exploited for therapeutic purposes in the context of cancer. In this review, we detail the development of highly immunodeficient mouse strains and the models currently used in cancer research. We summarize the latest improvements in adoptive natural killer (NK) cell therapies and the development of novel NK cell sources. Finally, we discuss the advantages of HIS mice to study the interactions between human NK cells and human cancers and to develop new therapeutic strategies.

  16. Radiobiological modeling with MarCell software

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, J.S.; Jones, T.D. [Oak Ridge National Lab., TN (United States). Health Sciences Research Div.


    A nonlinear system of differential equations that models the bone marrow cellular kinetics associated with radiation injury, molecular repair, and compensatory cell proliferation has been extensively documented. Recently, that model has been implemented as MarCell, a user-friendly MS-DOS computer program that allows users with little knowledge of the original model to evaluate complex radiation exposure scenarios. The software allows modeling with the following radiations: tritium beta, 100 kVp X, 250 kVp X, 22 MV X, {sup 60}Co, {sup 137}Cs, 2 MeV electrons, triga neutrons, D-T neutrons, and 3 blends of mixed-field fission radiations. The possible cell lineages are stem, stroma, and leukemia/lymphoma, and the available species include mouse, rat, dog, sheep, swine, burro, and man. An attractive mathematical feature is that any protracted protocol can be expressed as an equivalent prompt dose for either the source used or for a reference, such as 250 kVp X rays or {sup 60}Co. Output from MarCell includes: risk of 30-day mortality; risk of cancer and leukemia based either on cytopenia or compensatory cell proliferation; cell survival plots as a function of time or dose; and 4-week recovery kinetics following treatment. In this article, the program`s applicability and ease of use are demonstrated by evaluating a medical total body irradiation protocol and a nuclear fallout scenario.

  17. Morphogenesis and Regulation of Bergmann Glial Processes During Purkinje Cell Dendritic Spine Ensheathment and Synaptogenesis

    Institute of Scientific and Technical Information of China (English)



    星形胶质细胞在突触形成中发挥重要作用,但星形胶质细胞突起如何在发育过程中与突触结构相联系还不是很清楚.本文分析在小脑突触发生过程中Bergmann胶质细胞(BG)突起生长的类型.本文发现在这个过程中,BG突起向外生长与树突棘增多的包被作用相关.此外,双光子时间分辩显像显示BG突起是高度动态的,在棘包被过程中突起趋于稳定.虽然突触活力依赖于肌动蛋白的聚合作用,但细胞骨架调节器Ratl和RhoG的活动在胶质细胞突起的动力或密度上并未发挥作用,而是对于保持突起长度起关键性作用.本文扩展这个发现,探查突起形态和包被之间的关系,发现缩短的突起导致棘覆盖的减少.本文进一步发现在BG表达dn-Racl和低水平突触包被的区域,显示突触数量的增加.这些分析提示BG突起如何生长并包围突触结构,阐明BG突起结构对突触包被适当发育的重要性,并提示包被在突触形成中的作用.%Astrocytes have an important role in synaptic formation and function but how astrocytic processes be-come associated with synaptic structures during development is not well understood. Here we analyzed the pattern of growth of the processes extending off the main Bergmann glial (BG) shafts during synaptogenesis in the cerebellum.We found that during this period, BG process outgrowth was correlated with increased ensheathment of dendritic spines. Inaddition, two-photon time-lapse imaging revealed that BG processes were highly dynamic, and processes became more stable as the period of spine ensheathment progressed. While process motility was dependent on actin polymerization, activity of cytoskeletal regulators Racl and RhoG did not play a role in glial process dynamics or density, but was critical for maintaining process length. We extended this finding to probe the relationship between process morphology and ensheathment, finding that shortened processes result in decreased coverage of the spine.Furthermore, we found that areas in which BG expressed dn-Racl, and therefore had a lower level of synaptic en-sheathment, showed an overall increase in synapse number. These analyses reveal how BG processes grow to sur-round synaptic structures, elucidate the importance of BG process structure for proper development of synaptic en-sheathment, and reveal a role for ensheathment in synapse formation. V 2008 Wiley-Liss, Inc.

  18. Acid-sensitive channel inhibition prevents fetal alcohol spectrum disorders cerebellar Purkinje cell loss


    Ramadoss, Jayanth; Lunde, Emilie R.; Ouyang, Nengtai; Chen, Wei-Jung A.; Cudd, Timothy A.


    Ethanol is now considered the most common human teratogen. Educational campaigns have not reduced the incidence of ethanol-mediated teratogenesis, leading to a growing interest in the development of therapeutic prevention or mitigation strategies. On the basis of the observation that maternal ethanol consumption reduces maternal and fetal pH, we hypothesized that a pH-sensitive pathway involving the TWIK-related acid-sensitive potassium channels (TASKs) is implicated in ethanol-induced injury...

  19. Impact of Afferent Inputs on Purkinje Cell Spiking Patterns and Motor Coordination

    NARCIS (Netherlands)

    A.M. Badura (Aleksandra)


    textabstractThe brain is what makes us human. Feelings, memories, complex social interactions, language and movement – all of it originates in the brain. On average, the human brain contains approximately 50–100 billion neurons that communicate with each other through the vast network of 100 – 500 t

  20. Cause and Consequence of Purkinje Cell Signals in the Cerebellar Flocculus

    NARCIS (Netherlands)

    B.H.J. Winkelman (Beerend)


    markdownabstract__Abstract__ How environmental stimuli are processed by neural circuits and how neural circuits control behavior are fundamental questions in systems neuroscience, describing both ends of its research spectrum. At one end, neural structures can be identified that are dedicated to th

  1. Elevated mutant dynorphin A causes Purkinje cell loss and motor dysfunction in spinocerebellar ataxia type 23

    NARCIS (Netherlands)

    Smeets, Cleo J. L. M.; Jezierska, Justyna; Watanabe, Hiroyuki; Duarri Pique, Anna; Fokkens, Michiel R.; Meijer, Michel; Zhou, Qin; Yakovleva, Tania; Boddeke, Erik; den Dunnen, Wilfred; van Deursen, Jan; Bakalkin, Georgy; Kampinga, Harm H.; van de Sluis, Bart; Verbeek, Dineke S.


    Spinocerebellar ataxia type 23 is caused by mutations in PDYN, which encodes the opioid neuropeptide precursor protein, prodynorphin. Prodynorphin is processed into the opioid peptides, a-neoendorphin, and dynorphins A and B, that normally exhibit opioid-receptor mediated actions in pain signalling

  2. Alcohol impairs long-term depression at the cerebellar parallel fiber-Purkinje cell synapse

    NARCIS (Netherlands)

    A. Belmeguenai (Amor); P. Botta (Paolo); J.T. Weber (John); M. Carta (Mario); M.M. de Ruiter (Martijn); C.I. de Zeeuw (Chris); C.F. Valenzuela (Fernando); C.R.W. Hansel (Christian)


    textabstractAcute alcohol consumption causes deficits in motor coordination and gait, suggesting an involvement of cerebellar circuits, which play a role in the fine adjustment of movements and in motor learning. It has previously been shown that ethanol modulates inhibitory transmission in the cere

  3. Bonded-cell model for particle fracture. (United States)

    Nguyen, Duc-Hanh; Azéma, Emilien; Sornay, Philippe; Radjai, Farhang


    Particle degradation and fracture play an important role in natural granular flows and in many applications of granular materials. We analyze the fracture properties of two-dimensional disklike particles modeled as aggregates of rigid cells bonded along their sides by a cohesive Mohr-Coulomb law and simulated by the contact dynamics method. We show that the compressive strength scales with tensile strength between cells but depends also on the friction coefficient and a parameter describing cell shape distribution. The statistical scatter of compressive strength is well described by the Weibull distribution function with a shape parameter varying from 6 to 10 depending on cell shape distribution. We show that this distribution may be understood in terms of percolating critical intercellular contacts. We propose a random-walk model of critical contacts that leads to particle size dependence of the compressive strength in good agreement with our simulation data.

  4. Bonded-cell model for particle fracture


    Nguyen, Duc-Hanh; Azéma, Émilien; Sornay, Philippe; Radjaï, Farhang


    International audience; Particle degradation and fracture play an important role in natural granular flows and in many applications of granular materials. We analyze the fracture properties of two-dimensional disklike particles modeled as aggregates of rigid cells bonded along their sides by a cohesive Mohr-Coulomb law and simulated by the contact dynamics method. We show that the compressive strength scales with tensile strength between cells but depends also on the friction coefficient and ...

  5. Modeling traction forces in collective cell migration (United States)

    Zimmermann, Juliane; Basan, Markus; Hayes, Ryan L.; Rappel, Wouter-Jan; Levine, Herbert


    Collective cell migration is an important process in embryonic development, wound healing, and cancer metastasis. We have developed a particle-based simulation for collective cell migration that describes flow patterns and finger formation at the tissue edge observed in wound healing experiments. We can apply methods for calculating intercellular stress to our simulation model, and have thereby provided evidence for the validity of a stress reconstitution method from traction forces used in experiments. To accurately capture experimentally measured traction forces and stresses in the tissue, which are mostly tensile, we have to include intracellular acto-myosin contraction into our simulation. We can then reproduce the experimentally observed behavior of cells moving around a circular obstacle, and suggest underlying mechanisms for cell-cell alignment and generation of traction force patterns.

  6. Computational Modeling of Cell Survival Using VHDL

    Directory of Open Access Journals (Sweden)

    Shruti Jain1,


    Full Text Available The model for cell survival has been implemented using VeryHigh Speed Integrated Circuit Hardware DescriptionLanguage (VHDL (Xilinx Tool taking three input signals:Tumor necrosis factor-α (TNF, Epidermal growth factor(EGF and Insulin. Cell survival has been regulated by theinteraction of five proteins viz P13K, TNFR1, EGFR, IRS andIKK in a network. In the absence of any one, in protein networkleads to cell death. For the EGF input signal the proteins likeMEK, ERK, AkT, Rac & JNK have been important forregulation of cell survival. Similarly for TNF and Insulin inputsignal proteins like NFκB, AkT, XIAP, JNK, MAP3K & MK2and MEK, ERK, AkT, Rac, mTOR & JNK respectively havebeen important for regulation of cell survival.

  7. Optical models for silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, T.; Sopori, B. [National Renewable Energy Lab., Golden, CO (United States)


    Light trapping is an important design feature for high-efficiency silicon solar cells. Because light trapping can considerably enhance optical absorption, a thinner substrate can be used which, in turn, can lower the bulk carrier recombination and concommitantly increase open-circuit voltage, and fill factor of the cell. The basic concepts of light trapping are similar to that of excitation of an optical waveguide, where a prism or a grating structure increases the phase velocity of the incoming optical wave such that waves propagated within the waveguide are totally reflected at the interfaces. Unfortunately, these concepts break down because the entire solar cell is covered with such a structure, making it necessary to develop new analytical approaches to deal with incomplete light trapping in solar cells. This paper describes two models that analyze light trapping in thick and thin solar cells.

  8. Disruption of the LTD dialogue between the cerebellum and the cortex in Angelman syndrome model: a timing hypothesis

    Directory of Open Access Journals (Sweden)

    Guy eCheron


    Full Text Available Angelman syndrome is a genetic neurodevelopmental disorder in which cerebellar functioning impairment has been documented despite the absence of gross structural abnormalities. Characteristically, a spontaneous 160 Hz oscillation emerges in the Purkinje cells network of the Ube3am-/p+ Angelman mouse model. This abnormal oscillation is induced by enhanced Purkinje cell rhythmicity and hypersynchrony along the parallel fiber beam. We present a pathophysiological hypothesis for the neurophysiology underlying major aspects of the clinical phenotype of Angelman syndrome, including cognitive, language and motor deficits, involving long-range connection between the cerebellar and the cortical networks. This hypothesis states that the alteration of the cerebellar rhythmic activity impinges cerebellar long-term depression (LTD plasticity, which in turn alters the LTD plasticity in the cerebral cortex. This hypothesis was based on preliminary experiments using electrical stimulation of the whiskers pad performed in alert mice showing that after a 8 Hz LTD-inducing protocol, the cerebellar LTD accompanied by a delayed response in the wild type mice is missing in Ube3am-/p+ mice and that the LTD induced in the barrel cortex following the same peripheral stimulation in wild mice is reversed into a LTP in the Ube3am-/p+ mice. The control exerted by the cerebellum on the excitation vs inhibition balance in the cerebral cortex and possible role played by the timing plasticity of the Purkinje cell LTD on the spike–timing dependent plasticity (STDP of the pyramidal neurons are discussed in the context of the present hypothesis.

  9. Disruption of the LTD dialogue between the cerebellum and the cortex in Angelman syndrome model: a timing hypothesis. (United States)

    Cheron, Guy; Márquez-Ruiz, Javier; Kishino, Tatsuya; Dan, Bernard


    Angelman syndrome (AS) is a genetic neurodevelopmental disorder in which cerebellar functioning impairment has been documented despite the absence of gross structural abnormalities. Characteristically, a spontaneous 160 Hz oscillation emerges in the Purkinje cells network of the Ube3a (m-/p+) Angelman mouse model. This abnormal oscillation is induced by enhanced Purkinje cell rhythmicity and hypersynchrony along the parallel fiber beam. We present a pathophysiological hypothesis for the neurophysiology underlying major aspects of the clinical phenotype of AS, including cognitive, language and motor deficits, involving long-range connection between the cerebellar and the cortical networks. This hypothesis states that the alteration of the cerebellar rhythmic activity impinges cerebellar long-term depression (LTD) plasticity, which in turn alters the LTD plasticity in the cerebral cortex. This hypothesis was based on preliminary experiments using electrical stimulation of the whiskers pad performed in alert mice showing that after a 8 Hz LTD-inducing protocol, the cerebellar LTD accompanied by a delayed response in the wild type (WT) mice is missing in Ube3a (m-/p+) mice and that the LTD induced in the barrel cortex following the same peripheral stimulation in wild mice is reversed into a LTP in the Ube3a (m-/p+) mice. The control exerted by the cerebellum on the excitation vs. inhibition balance in the cerebral cortex and possible role played by the timing plasticity of the Purkinje cell LTD on the spike-timing dependent plasticity (STDP) of the pyramidal neurons are discussed in the context of the present hypothesis.

  10. Modeling cell-in-cell structure into its biological significance


    He, M-f; Wang, S.; Wang, Y; Wang, X-N.


    Although cell-in-cell structure was noted 100 years ago, the molecular mechanisms of ‘entering' and the destination of cell-in-cell remain largely unclear. It takes place among the same type of cells (homotypic cell-in-cell) or different types of cells (heterotypic cell-in-cell). Cell-in-cell formation affects both effector cells and their host cells in multiple aspects, while cell-in-cell death is under more intensive investigation. Given that cell-in-cell has an important role in maintainin...

  11. Modeling cell dynamics under mobile phone radiation. (United States)

    Minelli, Tullio Antonio; Balduzzo, Maurizio; Milone, Francesco Ferro; Nofrate, Valentina


    Perturbations by pulse-modulated microwave radiation from GSM mobile phones on neuron cell membrane gating and calcium oscillations have been suggested as a possible mechanism underlying activation of brain states and electroencephalographic epiphenomena. As the employ of UMTS phones seems to reveal other symptoms, a unified phenomenological framework is needed. In order to explain possible effects of mobile phone radiation on cell oscillations, GSM and UMTS low-frequency envelopes have been detected, recorded and used as input in cell models. Dynamical systems endowed with contiguous regular and chaotic regimes suitable to produce stochastic resonance can both account for the perturbation of the neuro-electrical activity and even for the low intensity of the signal perceived by high sensitive subjects. Neuron models of this kind can be employed as a reductionist hint for the mentioned phenomenology. The Hindmarsh-Rose model exhibits frequency enhancement and regularization phenomena induced by weak GSM and UMTS. More realistic simulations of cell membrane gating and calcium oscillations have been performed with the help of an adaptation of the Chay-Keizer dynamical system. This scheme can explain the suspected subjective sensitivity to mobile phone signals under the thermal threshold, in terms of cell calcium regularity mechanisms. Concerning the two kinds of emission, the stronger occupation of the ELF band of last generation UMTS phones is compensated by lower power emitted.

  12. Modeling sarcomagenesis using multipotent mesenchymal stem cells

    Institute of Scientific and Technical Information of China (English)

    Rene Rodriguez; Ruth Rubio; Pablo Menendez


    Because of their unique properties,multipotent mesenchymal stem cells (MSCs) represent one of the most promising adult stem cells being used worldwide in a wide array of clinical applications.Overall,compelling evidence supports the long-term safety of ex vivo expanded human MSCs,which do not seem to transform spontaneously.However,experimental data reveal a link between MSCs and cancer,and MSCs have been reported to inhibit or promote tumor growth depending on yet undefined conditions.Interestingly,solid evidence based on transgenic mice and genetic intervention of MSCs has placed these cells as the most likely cell of origin for certain sarcomas.This research area is being increasingly explored to develop accurate MSC-based models of sarcomagenesis,which will be undoubtedly valuable in providing a better understanding about the etiology and pathogenesis of mesenchymal cancer,eventually leading to the development of more specific therapies directed against the sarcoma-initiating cell.Unfortunately,still little is known about the mechanisms underlying MSC transformation and further studies are required to develop bona fide sarcoma models based on human MSCs.Here,we comprehensively review the existing MSC-based models of sarcoma and discuss the most common mechanisms leading to tumoral transformation of MSCs and sarcomagenesis.

  13. Voronoi cell patterns: Theoretical model and applications (United States)

    González, Diego Luis; Einstein, T. L.


    We use a simple fragmentation model to describe the statistical behavior of the Voronoi cell patterns generated by a homogeneous and isotropic set of points in 1D and in 2D. In particular, we are interested in the distribution of sizes of these Voronoi cells. Our model is completely defined by two probability distributions in 1D and again in 2D, the probability to add a new point inside an existing cell and the probability that this new point is at a particular position relative to the preexisting point inside this cell. In 1D the first distribution depends on a single parameter while the second distribution is defined through a fragmentation kernel; in 2D both distributions depend on a single parameter. The fragmentation kernel and the control parameters are closely related to the physical properties of the specific system under study. We use our model to describe the Voronoi cell patterns of several systems. Specifically, we study the island nucleation with irreversible attachment, the 1D car-parking problem, the formation of second-level administrative divisions, and the pattern formed by the Paris Métro stations.

  14. Biophysical models of transcription in cells (United States)

    Choubey, Sandeep

    Cells constantly face environmental challenges and deal with them by changing their gene expression patterns. They make decisions regarding which genes to express and which genes not to express based on intra-cellular and environmental cues. These decisions are often made by regulating the process of transcription. While the identities of the different molecules that take part in regulating transcription have been determined for a number of different genes, their dynamics inside the cell are still poorly understood. One key feature of these regulatory dynamics is that the numbers of the bio-molecules involved is typically small, resulting in large temporal fluctuations in transcriptional outputs (mRNA and protein). In this thesis I show that measurements of the cell-to-cell variability of the distribution of transcribing RNA polymerases along a gene provide a previously unexplored method for deciphering the mechanism of its transcription in vivo. First, I propose a simple kinetic model of transcription initiation and elongation from which I calculate transcribing RNA polymerase copy-number fluctuations. I test my theory against published data obtained for yeast genes and propose a novel mechanism of transcription. Rather than transcription being initiated through a single rate-limiting step, as was previously proposed, my single-cell analysis reveals the presence of at least two rate limiting steps. Second, I compute the distribution of inter-polymerase distance distribution along a gene and propose a method for analyzing inter-polymerase distance distributions acquired in experiments. By applying this method to images of polymerases transcribing ribosomal genes in E.coli I show that one model of regulation of these genes is consistent with inter-polymerase distance data while a number of other models are not. The analytical framework described in this thesis can be used to extract quantitative information about the dynamics of transcription from single-cell

  15. What cycles the cell? -Robust autonomous cell cycle models. (United States)

    Lavi, Orit; Louzoun, Yoram


    The cell cycle is one of the best studied cellular mechanisms at the experimental and theoretical levels. Although most of the important biochemical components and reactions of the cell cycle are probably known, the precise way the cell cycle dynamics are driven is still under debate. This phenomenon is not atypical to many other biological systems where the knowledge of the molecular building blocks and the interactions between them does not lead to a coherent picture of the appropriate dynamics. We here propose a methodology to develop plausible models for the driving mechanisms of embryonic and cancerous cell cycles. We first define a key property of the system (a cyclic behaviour in the case of the embryonic cell cycle) and set mathematical constraints on the types of two variable simplified systems robustly reproducing such a cyclic behaviour. We then expand these robust systems to three variables and reiterate the procedure. At each step, we further limit the type of expanded systems to fit the known microbiology until a detailed description of the system is obtained. This methodology produces mathematical descriptions of the required biological systems that are more robust to changes in the precise function and rate constants. This methodology can be extended to practically any type of subcellular mechanism.

  16. Non linear behaviour of cell tensegrity models (United States)

    Alippi, A.; Bettucci, A.; Biagioni, A.; Conclusio, D.; D'Orazio, A.; Germano, M.; Passeri, D.


    Tensegrity models for the cytoskeleton structure of living cells is largely used nowadays for interpreting the biochemical response of living tissues to mechanical stresses. Microtubules, microfilaments and filaments are the microscopic cell counterparts of struts (microtubules) and cables (microfilaments and filaments) in the macroscopic world: the formers oppose to compression, the latters to tension, thus yielding an overall structure, light and highly deformable. Specific cell surface receptors, such as integrins, act as the coupling elements that transmit the outside mechanical stress state into the cell body. Reversible finite deformations of tensegrity structures have been widely demonstrated experimentally and in a number of living cell simulations. In the present paper, the bistability behaviour of two general models, the linear bar oscillator and the icosahedron, is studied, as they are both obtained from mathematical simulation, the former, and from larger scale experiments, the latter. The discontinuity in the frequency response of the oscillation amplitude and the lateral bending of the resonance curves are put in evidence, as it grows larger as the driving amplitude increases, respectively.

  17. Subcellular structural plasticity caused by the absence of the fast Ca2+ buffer calbindin D-28k in recurrent collaterals of cerebellar Purkinje neurons

    Directory of Open Access Journals (Sweden)

    David eOrduz


    Full Text Available Purkinje cells (PC control spike timing of neighboring PC by their recurrent axon collaterals. These synapses underlie fast cerebellar oscillations and are characterized by a strong facilitation within a time window of <20 ms during paired-pulse protocols. PC express high levels of the fast Ca2+ buffer protein calbindin D-28k (CB. As expected from the absence of a fast Ca2+ buffer, presynaptic action potential-evoked [Ca2+]i transients were previously shown to be bigger in PC boutons of young (second postnatal week CB-/- mice, yet IPSC mean amplitudes remained unaltered in connected CB-/- PC. Since PC spine morphology is altered in adult CB-/- mice (longer necks, larger spine head volume, we summoned that morphological compensation/adaptation mechanisms might also be induced in CB-/- PC axon collaterals including boutons. In these mice, biocytin-filled PC reconstructions revealed that the number of axonal varicosities per PC axon collateral was augmented, mostly confined to the granule cell layer. Additionally, the volume of individual boutons was increased, evidenced from z-stacks of confocal images. EM analysis of PC-PC synapses revealed an enhancement in active zone (AZ length by approximately 23%, paralleled by a higher number of docked vesicles per AZ in CB-/- boutons. Moreover, synaptic cleft width was larger in CB-/- (23.8 ± 0.43 nm compared to wild type (21.17 ± 0.39 nm synapses. We propose that the morphological changes, i.e. the larger bouton volume, the enhanced AZ length and the higher number of docked vesicles, in combination with the increase in synaptic cleft width likely modifies the GABA release properties at this synapse in CB-/- mice. We view these changes as adaptation/homeostatic mechanisms to likely maintain (preserve characteristics of synaptic transmission in the absence of the fast Ca2+ buffer CB. Our study provides further evidence on the functioning of the Ca2+ homeostasome.

  18. Modeling light trapping in nanostructured solar cells. (United States)

    Ferry, Vivian E; Polman, Albert; Atwater, Harry A


    The integration of nanophotonic and plasmonic structures with solar cells offers the ability to control and confine light in nanoscale dimensions. These nanostructures can be used to couple incident sunlight into both localized and guided modes, enhancing absorption while reducing the quantity of material. Here we use electromagnetic modeling to study the resonances in a solar cell containing both plasmonic metal back contacts and nanostructured semiconductor top contacts, identify the local and guided modes contributing to enhanced absorption, and optimize the design. We then study the role of the different interfaces and show that Al is a viable plasmonic back contact material.

  19. A dynamic model of tomato fruit growth integrating cell division, cell growth and endoreduplication

    NARCIS (Netherlands)

    Fanwoua, J.; Visser, de P.H.B.; Heuvelink, E.; Yin, X.; Struik, P.C.; Marcelis, L.F.M.


    In this study, we developed a model of tomato (Solanum lycopersicum L.) fruit growth integrating cell division, cell growth and endoreduplication. The fruit was considered as a population of cells grouped in cell classes differing in their initial cell age and cell mass. The model describes fruit gr

  20. Exploring leptin antagonism in ophthalmic cell models.

    Directory of Open Access Journals (Sweden)

    Laura Scolaro

    Full Text Available BACKGROUND: Emerging evidence suggests that angiogenic and pro-inflammatory cytokine leptin might be implicated in ocular neovascularization. However, the potential of inhibiting leptin function in ophthalmic cells has never been explored. Here we assessed mitogenic, angiogenic, and signaling leptin activities in retinal and corneal endothelial cells and examined the capability of a specific leptin receptor (ObR antagonist, Allo-aca, to inhibit these functions. METHODS AND RESULTS: The experiments were carried out in monkey retinal (RF/6A and bovine corneal (BCE endothelial cells. Leptin at 50-250 ng/mL stimulated the growth of both cell lines in a dose-dependent manner. The maximal mitogenic response (35±7 and 27±3% in RF6A and BCE cells, respectively was noted at 24 h of 250 ng/mL leptin treatments. Leptin-dependent proliferation was reduced to base levels with 10 and 100 nM Allo-aca in BCE and RF6A cells, respectively. In both cell lines, leptin promoted angiogenic responses, with the maximal increase in tube formation (163±10 and 133±8% in RF6A and BCE cultures, respectively observed under a 250 ng/mL leptin treatment for 3 h. Furthermore, in both cell lines 250 ng/mL leptin modulated the activity or expression of several signaling molecules involved in proliferation, inflammatory activity and angiogenesis, such as STAT3, Akt, and ERK1/2, COX2, and NFκB. In both cell lines, leptin-induced angiogenic and signaling responses were significantly inhibited with 100 nM Allo-aca. We also found that leptin increased its own mRNA and protein expression in both cell lines, and this autocrine effect was abolished by 100-250 nM Allo-aca. CONCLUSIONS: Our data provide new insights into the role of leptin in ocular endothelial cells and represent the first original report on targeting ObR in ophthalmic cell models.

  1. Temperature-dependent rate models of vascular cambium cell mortality (United States)

    Matthew B. Dickinson; Edward A. Johnson


    We use two rate-process models to describe cell mortality at elevated temperatures as a means of understanding vascular cambium cell death during surface fires. In the models, cell death is caused by irreversible damage to cellular molecules that occurs at rates that increase exponentially with temperature. The models differ in whether cells show cumulative effects of...

  2. Modeling malaria infected cells in microcirculation (United States)

    Raffiee, Amir Hossein; Dabiri, Sadegh; Motavalizadeh Ardekani, Arezoo


    Plasmodim (P.) falciparum is one of the deadliest types of malaria species that invades healthy red blood cells (RBC) in human blood flow. This parasite develops through 48-hour intra-RBC process leading to significant morphological and mechanical (e.g., stiffening) changes in RBC membrane. These changes have remarkable effects on blood circulation such as increase in flow resistance and obstruction in microcirculation. In this work a computational framework is developed to model RBC suspension in blood flow using front-tracking technique. The present study focuses on blood flow behavior under normal and infected circumstances and predicts changes in blood rheology for different levels of parasitemia and hematocrit. This model allows better understanding of blood flow circulation up to a single cell level and provides us with realistic and deep insight into hematologic diseases such as malaria.

  3. Interaction of Defensins with Model Cell Membranes (United States)

    Sanders, Lori K.; Schmidt, Nathan W.; Yang, Lihua; Mishra, Abhijit; Gordon, Vernita D.; Selsted, Michael E.; Wong, Gerard C. L.


    Antimicrobial peptides (AMPs) comprise a key component of innate immunity for a wide range of multicellular organisms. For many AMPs, activity comes from their ability to selectively disrupt and lyse bacterial cell membranes. There are a number of proposed models for this action, but the detailed molecular mechanism of selective membrane permeation remains unclear. Theta defensins are circularized peptides with a high degree of selectivity. We investigate the interaction of model bacterial and eukaryotic cell membranes with theta defensins RTD-1, BTD-7, and compare them to protegrin PG-1, a prototypical AMP, using synchrotron small angle x-ray scattering (SAXS). The relationship between membrane composition and peptide induced changes in membrane curvature and topology is examined. By comparing the membrane phase behavior induced by these different peptides we will discuss the importance of amino acid composition and placement on membrane rearrangement.

  4. Modeling of SONOS Memory Cell Erase Cycle (United States)

    Phillips, Thomas A.; MacLeod, Todd C.; Ho, Fat H.


    Utilization of Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) nonvolatile semiconductor memories as a flash memory has many advantages. These electrically erasable programmable read-only memories (EEPROMs) utilize low programming voltages, have a high erase/write cycle lifetime, are radiation hardened, and are compatible with high-density scaled CMOS for low power, portable electronics. In this paper, the SONOS memory cell erase cycle was investigated using a nonquasi-static (NQS) MOSFET model. Comparisons were made between the model predictions and experimental data.

  5. Generative models: Human embryonic stem cells and multiple modeling relations. (United States)

    Fagan, Melinda Bonnie


    Model organisms are at once scientific models and concrete living things. It is widely assumed by philosophers of science that (1) model organisms function much like other kinds of models, and (2) that insofar as their scientific role is distinctive, it is in virtue of representing a wide range of biological species and providing a basis for generalizations about those targets. This paper uses the case of human embryonic stem cells (hESC) to challenge both assumptions. I first argue that hESC can be considered model organisms, analogous to classic examples such as Escherichia coli and Drosophila melanogaster. I then discuss four contrasts between the epistemic role of hESC in practice, and the assumptions about model organisms noted above. These contrasts motivate an alternative view of model organisms as a network of systems related constructively and developmentally to one another. I conclude by relating this result to other accounts of model organisms in recent philosophy of science. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Modeling Morphogenesis in silico and in vitro: Towards Quantitative, Predictive, Cell-based Modeling

    NARCIS (Netherlands)

    R.M.H. Merks (Roeland); P. Koolwijk


    htmlabstractCell-based, mathematical models help make sense of morphogenesis—i.e. cells organizing into shape and pattern—by capturing cell behavior in simple, purely descriptive models. Cell-based models then predict the tissue-level patterns the cells produce collectively. The first

  7. Modeling Anomalous Hysteresis in Perovskite Solar Cells. (United States)

    van Reenen, Stephan; Kemerink, Martijn; Snaith, Henry J


    Organic-inorganic lead halide perovskites are distinct from most other semiconductors because they exhibit characteristics of both electronic and ionic motion. Accurate understanding of the optoelectronic impact of such properties is important to fully optimize devices and be aware of any limitations of perovskite solar cells and broader optoelectronic devices. Here we use a numerical drift-diffusion model to describe device operation of perovskite solar cells. To achieve hysteresis in the modeled current-voltage characteristics, we must include both ion migration and electronic charge traps, serving as recombination centers. Trapped electronic charges recombine with oppositely charged free electronic carriers, of which the density depends on the bias-dependent ion distribution in the perovskite. Our results therefore show that reduction of either the density of mobile ionic species or carrier trapping at the perovskite interface will remove the adverse hysteresis in perovskite solar cells. This gives a clear target for ongoing research effort and unifies previously conflicting experimental observations and theories.

  8. Prenatal hypoxic-ischemic insult changes the distribution and number of NADPH-diaphorase cells in the cerebellum.

    Directory of Open Access Journals (Sweden)

    Tiago Savignon

    Full Text Available Astrogliosis, oligodendroglial death and motor deficits have been observed in the offspring of female rats that had their uterine arteries clamped at the 18(th gestational day. Since nitric oxide has important roles in several inflammatory and developmental events, here we evaluated NADPH-diaphorase (NADPH-d distribution in the cerebellum of rats submitted to this hypoxia-ischemia (HI model. At postnatal (P day 9, Purkinje cells of SHAM and non-manipulated (NM animals showed NADPH-d+ labeling both in the cell body and dendritic arborization in folia 1 to 8, while HI animals presented a weaker labeling in both cellular structures. NADPH-d+ labeling in the molecular (ML, and in both the external and internal granular layer, was unaffected by HI at this age. At P23, labeling in Purkinje cells was absent in all three groups. Ectopic NADPH-d+ cells in the ML of folia 1 to 4 and folium 10 were present exclusively in HI animals. This labeling pattern was maintained up to P90 in folium 10. In the cerebellar white matter (WM, at P9 and P23, microglial (ED1+ NADPH-d+ cells, were observed in all groups. At P23, only HI animals presented NADPH-d labeling in the cell body and processes of reactive astrocytes (GFAP+. At P9 and P23, the number of NADPH-d+ cells in the WM was higher in HI animals than in SHAM and NM ones. At P45 and at P90 no NADPH-d+ cells were observed in the WM of the three groups. Our results indicate that HI insults lead to long-lasting alterations in nitric oxide synthase expression in the cerebellum. Such alterations in cerebellar differentiation might explain, at least in part, the motor deficits that are commonly observed in this model.

  9. Advanced methods of solid oxide fuel cell modeling

    CERN Document Server

    Milewski, Jaroslaw; Santarelli, Massimo; Leone, Pierluigi


    Fuel cells are widely regarded as the future of the power and transportation industries. Intensive research in this area now requires new methods of fuel cell operation modeling and cell design. Typical mathematical models are based on the physical process description of fuel cells and require a detailed knowledge of the microscopic properties that govern both chemical and electrochemical reactions. ""Advanced Methods of Solid Oxide Fuel Cell Modeling"" proposes the alternative methodology of generalized artificial neural networks (ANN) solid oxide fuel cell (SOFC) modeling. ""Advanced Methods

  10. Modeling Degradation in Solid Oxide Electrolysis Cells

    Energy Technology Data Exchange (ETDEWEB)

    Manohar S. Sohal; Anil V. Virkar; Sergey N. Rashkeev; Michael V. Glazoff


    Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells (SOECs). To accomplish this, technical and degradation issues associated with the SOECs will need to be addressed. This report covers various approaches being pursued to model degradation issues in SOECs. An electrochemical model for degradation of SOECs is presented. The model is based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic no equilibrium. It is shown that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential, , within the electrolyte. The within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just near the oxygen electrode/electrolyte interface, leading to oxygen electrode delamination. These predictions are in accordance with the reported literature on the subject. Development of high pressures may be avoided by introducing some electronic conduction in the electrolyte. By combining equilibrium thermodynamics, no equilibrium (diffusion) modeling, and first-principles, atomic scale calculations were performed to understand the degradation mechanisms and provide practical recommendations on how to inhibit and/or completely mitigate them.

  11. Modelling familial dysautonomia in human induced pluripotent stem cells


    Lee, Gabsang; Studer, Lorenz


    Induced pluripotent stem (iPS) cells have considerable promise as a novel tool for modelling human disease and for drug discovery. While the generation of disease-specific iPS cells has become routine, realizing the potential of iPS cells in disease modelling poses challenges at multiple fronts. Such challenges include selecting a suitable disease target, directing the fate of iPS cells into symptom-relevant cell populations, identifying disease-related phenotypes and showing reversibility of...

  12. A Physics-based Analytical Model for Perovskite Solar Cells


    Sun, Xingshu; Asadpour, Reza; Nie, Wanyi; Mohite, Aditya D.; Alam, Muhammad A.


    Perovskites are promising next-generation absorber materials for low-cost and high-efficiency solar cells. Although perovskite cells are configured similar to the classical solar cells, their operation is unique and requires development of a new physical model for characterization, optimization of the cells, and prediction of the panel performance. In this paper, we develop such a physics-based analytical model to describe the operation of different types of perovskite solar cells, explicitly...

  13. A transient model to simulate HTPEM fuel cell impedance spectra

    DEFF Research Database (Denmark)

    Vang, Jakob Rabjerg; Andreasen, Søren Juhl; Kær, Søren Knudsen


    This paper presents a spatially resolved transient fuel cell model applied to the simulation of high temperature PEM fuel cell impedance spectra. The model is developed using a 2D finite volume method approach. The model is resolved along the channel and across the membrane. The model considers...

  14. Biomechanics of epithelial cell islands analyzed by modeling and experimentation

    CERN Document Server

    Coburn, Luke; Noppe, Adrian; Caldwell, Benjamin J; Moussa, Elliott; Yap, Chloe; Priya, Rashmi; Lobaskin, Vladimir; Roberts, Anthony P; Yap, Alpha S; Neufeld, Zoltan; Gomez, Guillermo A


    We generated a new computational approach to analyze the biomechanics of epithelial cell islands that combines both vertex and contact-inhibition-of-locomotion models to include both cell-cell and cell-substrate adhesion. Examination of the distribution of cell protrusions (adhesion to the substrate) in the model predicted high order profiles of cell organization that agree with those previously seen experimentally. Cells acquired an asymmetric distribution of protrusions (and traction forces) that decreased when moving from the edge to the island center. Our in silico analysis also showed that tension on cell-cell junctions (and monolayer stress) is not homogeneous across the island. Instead it is higher at the island center and scales up with island size, which we confirmed experimentally using laser ablation assays and immunofluorescence. Moreover, our approach has the minimal elements necessary to reproduce mechanical crosstalk between both cell-cell and cell substrate adhesion systems. We found that an i...

  15. A sub-cellular viscoelastic model for cell population mechanics.

    Directory of Open Access Journals (Sweden)

    Yousef Jamali

    Full Text Available Understanding the biomechanical properties and the effect of biomechanical force on epithelial cells is key to understanding how epithelial cells form uniquely shaped structures in two or three-dimensional space. Nevertheless, with the limitations and challenges posed by biological experiments at this scale, it becomes advantageous to use mathematical and 'in silico' (computational models as an alternate solution. This paper introduces a single-cell-based model representing the cross section of a typical tissue. Each cell in this model is an individual unit containing several sub-cellular elements, such as the elastic plasma membrane, enclosed viscoelastic elements that play the role of cytoskeleton, and the viscoelastic elements of the cell nucleus. The cell membrane is divided into segments where each segment (or point incorporates the cell's interaction and communication with other cells and its environment. The model is capable of simulating how cells cooperate and contribute to the overall structure and function of a particular tissue; it mimics many aspects of cellular behavior such as cell growth, division, apoptosis and polarization. The model allows for investigation of the biomechanical properties of cells, cell-cell interactions, effect of environment on cellular clusters, and how individual cells work together and contribute to the structure and function of a particular tissue. To evaluate the current approach in modeling different topologies of growing tissues in distinct biochemical conditions of the surrounding media, we model several key cellular phenomena, namely monolayer cell culture, effects of adhesion intensity, growth of epithelial cell through interaction with extra-cellular matrix (ECM, effects of a gap in the ECM, tensegrity and tissue morphogenesis and formation of hollow epithelial acini. The proposed computational model enables one to isolate the effects of biomechanical properties of individual cells and the

  16. Proceedings of the NETL Workshop on Fuel Cell Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Randall S. Gemmen; J. R. Selman


    This workshop was the first U.S. DOE sponsored meeting devoted to fuel cell modeling. The workshop was attended by over 45 people from industry, universities, and the government. The goals of the meeting were to assess the status of fuel cell modeling, and determine how new developments in fuel cell modeling can improve cell design, stack design, and power system design. The primary focus was on cell and stack modeling. Following a review of DOE/NETL fuel cell related programs and activities, Professor Robert Selman (Illinois Institute of Technology) kicked off the technical portion of the workshop by presenting an overview of fuel cell phenomena and the status of fuel cell modeling. This overview provided the necessary background for establishing a common framework for discussing fuel cell modeling. A distinction was made between micro modeling, electrode modeling, cell modeling, stack modeling, and system modeling. It was proposed that all modeling levels be supported for further development. In addition, due to significant advances being made outside the U.S., it was proposed that dialog/exchange with other international researchers be established. Following the Overview Session, eight leading researchers in modeling gave individual presentations. These presentations provided additional information on the status and present direction of model developments. All these presentations can be found in Attachment A. Before the workshop, a survey was sent out requesting comments from the attendees. Results from this survey can be found in Attachment B. This survey was then used as initial talking points at the individual breakout sessions on the afternoon of the workshop. Breakouts were organized by microfundamental modeling, cell modeling, stack modeling, and systems modeling.

  17. Computational cell model based on autonomous cell movement regulated by cell-cell signalling successfully recapitulates the "inside and outside" pattern of cell sorting

    Directory of Open Access Journals (Sweden)

    Ajioka Itsuki


    Full Text Available Abstract Background Development of multicellular organisms proceeds from a single fertilized egg as the combined effect of countless numbers of cellular interactions among highly dynamic cells. Since at least a reminiscent pattern of morphogenesis can be recapitulated in a reproducible manner in reaggregation cultures of dissociated embryonic cells, which is known as cell sorting, the cells themselves must possess some autonomous cell behaviors that assure specific and reproducible self-organization. Understanding of this self-organized dynamics of heterogeneous cell population seems to require some novel approaches so that the approaches bridge a gap between molecular events and morphogenesis in developmental and cell biology. A conceptual cell model in a computer may answer that purpose. We constructed a dynamical cell model based on autonomous cell behaviors, including cell shape, growth, division, adhesion, transformation, and motility as well as cell-cell signaling. The model gives some insights about what cellular behaviors make an appropriate global pattern of the cell population. Results We applied the model to "inside and outside" pattern of cell-sorting, in which two different embryonic cell types within a randomly mixed aggregate are sorted so that one cell type tends to gather in the central region of the aggregate and the other cell type surrounds the first cell type. Our model can modify the above cell behaviors by varying parameters related to them. We explored various parameter sets with which the "inside and outside" pattern could be achieved. The simulation results suggested that direction of cell movement responding to its neighborhood and the cell's mobility are important for this specific rearrangement. Conclusion We constructed an in silico cell model that mimics autonomous cell behaviors and applied it to cell sorting, which is a simple and appropriate phenomenon exhibiting self-organization of cell population. The model

  18. Theoretical model of a photoelectrochemical solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, S.; Singh, S.L.; Khare, N.


    A Schottky barrier theoretical model for explaining the J-V characteristic of a photoelectrochemical solar cell (PESC) has been developed considering the effect of dark current, space-charge recombination, surface states, and detailed charge transfer kinetics at the interface. Both isoenergetic charge transfer and inelastic charge transfers (via surface states) at the interface have been considered and their relative importance are discussed. The theory has been applied to explain the (a) J-V characteristic for n-GaAs/SeS , SeS 2 junction and (b) Fermi-level pinning observed in GaAs PESC. The inelastic charge transfer via surfaces states has been shown to play an important role in deciding these characteristics.

  19. System-level modeling and simulation of the cell culture microfluidic biochip ProCell

    DEFF Research Database (Denmark)

    Minhass, Wajid Hassan; Pop, Paul; Madsen, Jan


    -defined micro-channels using valves and pumps. We present an approach to the system-level modeling and simulation of a cell culture microfluidic biochip called ProCell, Programmable Cell Culture Chip. ProCell contains a cell culture chamber, which is envisioned to run 256 simultaneous experiments (viewed...

  20. Modelling electrolyte conductivity in a water electrolyzer cell

    DEFF Research Database (Denmark)

    Caspersen, Michael; Kirkegaard, Julius Bier


    An analytical model describing the hydrogen gas evolution under natural convection in an electrolyzer cell is developed. Main purpose of the model is to investigate the electrolyte conductivity through the cell under various conditions. Cell conductivity is calculated from a parallel resistor app...... for electrolyte conductivity from combinations of pressure, current density and electrolyte width among others....

  1. Modeling keratinocyte wound healing dynamics: Cell-cell adhesion promotes sustained collective migration. (United States)

    Nardini, John T; Chapnick, Douglas A; Liu, Xuedong; Bortz, David M


    The in vitro migration of keratinocyte cell sheets displays behavioral and biochemical similarities to the in vivo wound healing response of keratinocytes in animal model systems. In both cases, ligand-dependent Epidermal Growth Factor Receptor (EGFR) activation is sufficient to elicit collective cell migration into the wound. Previous mathematical modeling studies of in vitro wound healing assays assume that physical connections between cells have a hindering effect on cell migration, but biological literature suggests a more complicated story. By combining mathematical modeling and experimental observations of collectively migrating sheets of keratinocytes, we investigate the role of cell-cell adhesion during in vitro keratinocyte wound healing assays. We develop and compare two nonlinear diffusion models of the wound healing process in which cell-cell adhesion either hinders or promotes migration. Both models can accurately fit the leading edge propagation of cell sheets during wound healing when using a time-dependent rate of cell-cell adhesion strength. The model that assumes a positive role of cell-cell adhesion on migration, however, is robust to changes in the leading edge definition and yields a qualitatively accurate density profile. Using RNAi for the critical adherens junction protein, α-catenin, we demonstrate that cell sheets with wild type cell-cell adhesion expression maintain migration into the wound longer than cell sheets with decreased cell-cell adhesion expression, which fails to exhibit collective migration. Our modeling and experimental data thus suggest that cell-cell adhesion promotes sustained migration as cells pull neighboring cells into the wound during wound healing.

  2. Validation of noise models for single-cell transcriptomics

    NARCIS (Netherlands)

    Grün, Dominic; Kester, Lennart; van Oudenaarden, Alexander


    Single-cell transcriptomics has recently emerged as a powerful technology to explore gene expression heterogeneity among single cells. Here we identify two major sources of technical variability: sampling noise and global cell-to-cell variation in sequencing efficiency. We propose noise models to co

  3. Process modeling of fuel cell vehicle power system

    Institute of Scientific and Technical Information of China (English)

    CHEN LiMing; LIN ZhaoJia; MA ZiFeng


    Constructed here is a mathematic model of PEM Fuel Cell Vehicle Power System which is composed of fuel supply model, fuel cell stack model and water-heat management model. The model was developed by Matiab/Simulink to evaluate how the major operating variables affect the output performances. Itshows that the constructed model can represent characteristics of the power system closely by comparing modeling results with experimental data, and it can be used in the study and design of fuel cell vehicle power system.

  4. Models of basal ganglia and cerebellum for sensorimotor integration and predictive control (United States)

    Jabri, Marwan A.; Huang, Jerry; Coenen, Olivier J. D.; Sejnowski, Terrence J.


    This paper presents a sensorimotor architecture integrating computational models of a cerebellum and a basal ganglia and operating on a microrobot. The computational models enable a microrobot to learn to track a moving object and anticipate future positions using a CCD camera. The architecture features pre-processing modules for coordinate transformation and instantaneous orientation extraction. Learning of motor control is implemented using predictive Hebbian reinforcement-learning algorithm in the basal ganglia model. Learning of sensory predictions makes use of a combination of long-term depression (LTD) and long-term potentiation (LTP) adaptation rules within the cerebellum model. The basal ganglia model uses the visual inputs to develop sensorimotor mapping for motor control, while the cerebellum module uses robot orientation and world- coordinate transformed inputs to predict the location of the moving object in a robot centered coordinate system. We propose several hypotheses about the functional role of cell populations in the cerebellum and argue that mossy fiber projections to the deep cerebellar nucleus (DCN) could play a coordinate transformation role and act as gain fields. We propose that such transformation could be learnt early in the brain development stages and could be guided by the activity of the climbing fibers. Proprioceptor mossy fibers projecting to the DCN and providing robot orientation with respect to a reference system could be involved in this case. Other mossy fibers carrying visual sensory input provide visual patterns to the granule cells. The combined activities of the granule and the Purkinje cells store spatial representations of the target patterns. The combinations of mossy and Purkinje projections to the DCN provide a prediction of the location of the moving target taking into consideration the robot orientation. Results of lesion simulations based on our model show degradations similar to those reported in cerebellar lesion

  5. Rotating cell culture systems for human cell culture: human trophoblast cells as a model. (United States)

    Zwezdaryk, Kevin J; Warner, Jessica A; Machado, Heather L; Morris, Cindy A; Höner zu Bentrup, Kerstin


    The field of human trophoblast research aids in understanding the complex environment established during placentation. Due to the nature of these studies, human in vivo experimentation is impossible. A combination of primary cultures, explant cultures and trophoblast cell lines support our understanding of invasion of the uterine wall and remodeling of uterine spiral arteries by extravillous trophoblast cells (EVTs), which is required for successful establishment of pregnancy. Despite the wealth of knowledge gleaned from such models, it is accepted that in vitro cell culture models using EVT-like cell lines display altered cellular properties when compared to their in vivo counterparts. Cells cultured in the rotating cell culture system (RCCS) display morphological, phenotypic, and functional properties of EVT-like cell lines that more closely mimic differentiating in utero EVTs, with increased expression of genes mediating invasion (e.g. matrix metalloproteinases (MMPs)) and trophoblast differentiation. The Saint Georges Hospital Placental cell Line-4 (SGHPL-4) (kindly donated by Dr. Guy Whitley and Dr. Judith Cartwright) is an EVT-like cell line that was used for testing in the RCCS. The design of the RCCS culture vessel is based on the principle that organs and tissues function in a three-dimensional (3-D) environment. Due to the dynamic culture conditions in the vessel, including conditions of physiologically relevant shear, cells grown in three dimensions form aggregates based on natural cellular affinities and differentiate into organotypic tissue-like assemblies. The maintenance of a fluid orbit provides a low-shear, low-turbulence environment similar to conditions found in vivo. Sedimentation of the cultured cells is countered by adjusting the rotation speed of the RCCS to ensure a constant free-fall of cells. Gas exchange occurs through a permeable hydrophobic membrane located on the back of the bioreactor. Like their parental tissue in vivo, RCCS

  6. Protection of neurons and microglia against ethanol in a mouse model of fetal alcohol spectrum disorders by peroxisome proliferator-activated receptor-γ agonists. (United States)

    Kane, Cynthia J M; Phelan, Kevin D; Han, Lihong; Smith, Renea R; Xie, Jin; Douglas, James C; Drew, Paul D


    Fetal alcohol spectrum disorders (FASD) result from ethanol exposure to the developing fetus and are the most common cause of mental retardation in the United States. These disorders are characterized by a variety of neurodevelopmental and neurodegenerative anomalies which result in significant lifetime disabilities. Thus, novel therapies are required to limit the devastating consequences of FASD. Neuropathology associated with FASD can occur throughout the central nervous system (CNS), but is particularly well characterized in the developing cerebellum. Rodent models of FASD have previously demonstrated that both Purkinje cells and granule cells, which are the two major types of neurons in the cerebellum, are highly susceptible to the toxic effects of ethanol. The current studies demonstrate that ethanol decreases the viability of cultured cerebellar granule cells and microglial cells. Interestingly, microglia have dual functionality in the CNS. They provide trophic and protective support to neurons. However, they may also become pathologically activated and produce inflammatory molecules toxic to parenchymal cells including neurons. The findings in this study demonstrate that the peroxisome proliferator-activated receptor-γ agonists 15-deoxy-Δ12,15 prostaglandin J2 and pioglitazone protect cultured granule cells and microglia from the toxic effects of ethanol. Furthermore, investigations using a newly developed mouse model of FASD and stereological cell counting methods in the cerebellum elucidate that ethanol administration to neonates is toxic to both Purkinje cell neurons as well as microglia, and that in vivo administration of PPAR-γ agonists protects these cells. In composite, these studies suggest that PPAR-γ agonists may be effective in limiting ethanol-induced toxicity to the developing CNS.

  7. Cell sources for in vitro human liver cell culture models. (United States)

    Zeilinger, Katrin; Freyer, Nora; Damm, Georg; Seehofer, Daniel; Knöspel, Fanny


    In vitro liver cell culture models are gaining increasing importance in pharmacological and toxicological research. The source of cells used is critical for the relevance and the predictive value of such models. Primary human hepatocytes (PHH) are currently considered to be the gold standard for hepatic in vitro culture models, since they directly reflect the specific metabolism and functionality of the human liver; however, the scarcity and difficult logistics of PHH have driven researchers to explore alternative cell sources, including liver cell lines and pluripotent stem cells. Liver cell lines generated from hepatomas or by genetic manipulation are widely used due to their good availability, but they are generally altered in certain metabolic functions. For the past few years, adult and pluripotent stem cells have been attracting increasing attention, due their ability to proliferate and to differentiate into hepatocyte-like cells in vitro However, controlling the differentiation of these cells is still a challenge. This review gives an overview of the major human cell sources under investigation for in vitro liver cell culture models, including primary human liver cells, liver cell lines, and stem cells. The promises and challenges of different cell types are discussed with a focus on the complex 2D and 3D culture approaches under investigation for improving liver cell functionality in vitro Finally, the specific application options of individual cell sources in pharmacological research or disease modeling are described.

  8. A novel mechanotactic 3D modeling of cell morphology (United States)

    Jamaleddin Mousavi, Seyed; Hamdy Doweidar, Mohamed


    Cell morphology plays a critical role in many biological processes, such as cell migration, tissue development, wound healing and tumor growth. Recent investigations demonstrate that, among other stimuli, cells adapt their shapes according to their substrate stiffness. Until now, the development of this process has not been clear. Therefore, in this work, a new three-dimensional (3D) computational model for cell morphology has been developed. This model is based on a previous cell migration model presented by the same authors. The new model considers that during cell-substrate interaction, cell shape is governed by internal cell deformation, which leads to an accurate prediction of the cell shape according to the mechanical characteristic of its surrounding micro-environment. To study this phenomenon, the model has been applied to different numerical cases. The obtained results, which are qualitatively consistent with well-known related experimental works, indicate that cell morphology not only depends on substrate stiffness but also on the substrate boundary conditions. A cell located within an unconstrained soft substrate (several kPa) with uniform stiffness is unable to adhere to its substrate or to send out pseudopodia. When the substrate stiffness increases to tens of kPa (intermediate and rigid substrates), the cell can adequately adhere to its substrate. Subsequently, as the traction forces exerted by the cell increase, the cell elongates and its shape changes. Within very stiff (hard) substrates, the cell cannot penetrate into its substrate or send out pseudopodia. On the other hand, a cell is found to be more elongated within substrates with a constrained surface. However, this elongation decreases when the cell approaches it. It can be concluded that the higher the net traction force, the greater the cell elongation, the larger the cell membrane area, and the less random the cell alignment.

  9. Periodic migration in a physical model of cells on micropatterns (United States)

    Camley, Brian A.; Zhao, Yanxiang; Li, Bo; Levine, Herbert; Rappel, Wouter-Jan


    We extend a model for the morphology and dynamics of a crawling eukaryotic cell to describe cells on micropatterned substrates. This model couples cell morphology, adhesion, and cytoskeletal flow in response to active stresses induced by actin and myosin. We propose that protrusive stresses are only generated where the cell adheres, leading to the cell's effective confinement to the pattern. Consistent with experimental results, simulated cells exhibit a broad range of behaviors, including steady motion, turning, bipedal motion, and periodic migration, in which the cell crawls persistently in one direction before reversing periodically. We show that periodic motion emerges naturally from the coupling of cell polarization to cell shape by reducing the model to a simplified one-dimensional form that can be understood analytically. PMID:24160631

  10. A minimal model for spontaneous cell polarization and edge activity in oscillating, rotating and migrating cells

    CERN Document Server

    Raynaud, Franck; Gabella, Chiara; Bornert, Alicia; Sbalzarini, Ivo F; Meister, Jean-Jacques; Verkhovsky, Alexander B


    How the cells break symmetry and organize their edge activity to move directionally is a fun- damental question in cell biology. Physical models of cell motility commonly rely on gradients of regulatory factors and/or feedback from the motion itself to describe polarization of edge activity. Theses approaches, however, fail to explain cell behavior prior to the onset of polarization. Our analysis using the model system of polarizing and moving fish epidermal keratocytes suggests a novel and simple principle of self-organization of cell activity in which local cell-edge dynamics depends on the distance from the cell center, but not on the orientation with respect to the front-back axis. We validate this principle with a stochastic model that faithfully reproduces a range of cell-migration behaviors. Our findings indicate that spontaneous polarization, persistent motion, and cell shape are emergent properties of the local cell-edge dynamics controlled by the distance from the cell center.

  11. A Predictive Model of Cell Traction Forces Based on Cell Geometry


    Lemmon, Christopher A.; Romer, Lewis H


    Recent work has indicated that the shape and size of a cell can influence how a cell spreads, develops focal adhesions, and exerts forces on the substrate. However, it is unclear how cell shape regulates these events. Here we present a computational model that uses cell shape to predict the magnitude and direction of forces generated by cells. The predicted results are compared to experimentally measured traction forces, and show that the model can predict traction force direction, relative m...

  12. A transient fuel cell model to simulate HTPEM fuel cell impedance spectra

    DEFF Research Database (Denmark)

    Vang, Jakob Rabjerg; Andreasen, Søren Juhl; Kær, Søren Knudsen


    This paper presents a spatially resolved transient fuel cell model applied to the simulation of high temperature PEM fuel cell impedance spectra. The model is developed using a 2D finite volume method approach. The model is resolved along the channel and across the membrane. The model considers d...

  13. A new level set model for cell image segmentation (United States)

    Ma, Jing-Feng; Hou, Kai; Bao, Shang-Lian; Chen, Chun


    In this paper we first determine three phases of cell images: background, cytoplasm and nucleolus according to the general physical characteristics of cell images, and then develop a variational model, based on these characteristics, to segment nucleolus and cytoplasm from their relatively complicated backgrounds. In the meantime, the preprocessing obtained information of cell images using the OTSU algorithm is used to initialize the level set function in the model, which can speed up the segmentation and present satisfactory results in cell image processing.

  14. A new level set model for cell image segmentation

    Institute of Scientific and Technical Information of China (English)

    Ma Jing-Feng; Hou Kai; Bao Shang-Lian; Chen Chun


    In this paper we first determine three phases of cell images: background, cytoplasm and nucleolus according to the general physical characteristics of cell images, and then develop a variational model, based on these characteristics, to segment nucleolus and cytoplasm from their relatively complicated backgrounds. In the meantime, the preprocessing obtained information of cell images using the OTSU algorithm is used to initialize the level set function in the model, which can speed up the segmentation and present satisfactory results in cell image processing.

  15. Kinetic models in industrial biotechnology - Improving cell factory performance. (United States)

    Almquist, Joachim; Cvijovic, Marija; Hatzimanikatis, Vassily; Nielsen, Jens; Jirstrand, Mats


    An increasing number of industrial bioprocesses capitalize on living cells by using them as cell factories that convert sugars into chemicals. These processes range from the production of bulk chemicals in yeasts and bacteria to the synthesis of therapeutic proteins in mammalian cell lines. One of the tools in the continuous search for improved performance of such production systems is the development and application of mathematical models. To be of value for industrial biotechnology, mathematical models should be able to assist in the rational design of cell factory properties or in the production processes in which they are utilized. Kinetic models are particularly suitable towards this end because they are capable of representing the complex biochemistry of cells in a more complete way compared to most other types of models. They can, at least in principle, be used to in detail understand, predict, and evaluate the effects of adding, removing, or modifying molecular components of a cell factory and for supporting the design of the bioreactor or fermentation process. However, several challenges still remain before kinetic modeling will reach the degree of maturity required for routine application in industry. Here we review the current status of kinetic cell factory modeling. Emphasis is on modeling methodology concepts, including model network structure, kinetic rate expressions, parameter estimation, optimization methods, identifiability analysis, model reduction, and model validation, but several applications of kinetic models for the improvement of cell factories are also discussed.

  16. A stochastic model of a cell population with quiescence. (United States)

    Olofsson, Peter


    A cell population in which cells are allowed to enter a quiescent (nonproliferating) phase is analyzed using a stochastic approach. A general branching process is used to model the population which, under very mild conditions, exhibits balanced exponential growth. A formula is given for the asymptotic fraction of quiescent cells, and a numerical example illustrates how convergence toward the asymptotic fraction exhibits a typical oscillatory pattern. The model is compared with deterministic models based on semigroup analysis of systems of differential equations.

  17. Modeling Of Proton Exchange Membrane Fuel Cell Systems

    DEFF Research Database (Denmark)

    Nielsen, Mads Pagh

    The objective of this doctoral thesis was to develop reliable steady-state and transient component models suitable to asses-, develop- and optimize proton exchange membrane (PEM) fuel cell systems. Several components in PEM fuel cell systems were characterized and modeled. The developed component...... cell systems. Consequences of indirectly fueling PEM stacks with hydrocarbons using reforming technology were investigated using a PEM stack model including CO poisoning kinetics and a transient Simulink steam reforming system model. Aspects regarding the optimization of PEM fuel cell systems...

  18. A non-local evolution equation model of cell-cell adhesion in higher dimensional space. (United States)

    Dyson, Janet; Gourley, Stephen A; Webb, Glenn F


    A model for cell-cell adhesion, based on an equation originally proposed by Armstrong et al. [A continuum approach to modelling cell-cell adhesion, J. Theor. Biol. 243 (2006), pp. 98-113], is considered. The model consists of a nonlinear partial differential equation for the cell density in an N-dimensional infinite domain. It has a non-local flux term which models the component of cell motion attributable to cells having formed bonds with other nearby cells. Using the theory of fractional powers of analytic semigroup generators and working in spaces with bounded uniformly continuous derivatives, the local existence of classical solutions is proved. Positivity and boundedness of solutions is then established, leading to global existence of solutions. Finally, the asymptotic behaviour of solutions about the spatially uniform state is considered. The model is illustrated by simulations that can be applied to in vitro wound closure experiments.

  19. Modelling planar cell polarity in Drosophila melanogaster



    During development, polarity is a common feature of many cell types. One example is the polarisation of whole fields of epithelial cells within the plane of the epithelium, a phenomenon called planar cell polarity (PCP). It is widespread in nature and plays important roles in development and physiology. Prominent examples include the epithelial cells of external structures of insects like the fruit fly Drosophila melanogaster, polarised tissue morphogenesis in vertebrates and sensory hair cel...

  20. Theoretical models for T-cell vaccination

    NARCIS (Netherlands)

    Boer, R.J. de; Borghans, J.A.M.


    T cell vaccination (TCV) is a term for a whole collection of phenomena in which the injection of T cells provides protection against autoimmunity. Vaccination with T cells has been investigated for several autoimmune diseases, including experimental autoimmune encephalomyelitis, adjuvant arthritist

  1. Trichomes as models for studying plant cell differentiation. (United States)

    Yang, Changxian; Ye, Zhibiao


    Trichomes, originating from epidermal cells, are present on nearly all terrestrial plants. They exist in diverse forms, are readily accessible, and serve as an excellent model system for analyzing the molecular mechanisms in plant cell differentiation, including cell fate choices, cell cycle control, and cell morphogenesis. In Arabidopsis, two regulatory models have been identified that function in parallel in trichome formation; the activator-inhibitor model and the activator-depletion model. Cotton fiber, a similar unicellular structure, is controlled by some functional homologues of Arabidopsis trichome-patterning genes. Multicellular trichomes, as in tobacco and tomato, may form through a distinct pathway from unicellular trichomes. Recent research has shown that cell cycle control participates in trichome formation. In this review, we summarize the molecular mechanisms involved in the formation of unicellular and multicellular trichomes, and discuss the integration of the cell cycle in its initiation and morphogenesis.

  2. Mathematical Model of an Inductive Measuring Cell for Contactless Conductometry

    CERN Document Server

    Semenov, Yury S


    A research of inductive conductometric cell is presented. An equivalent circuit and a mathematical model of inductive cell are given in the article. The model takes into account sample-coil capacity (i.e. capacity formed by the coil and the sample under study) and eddy currents. It is sample-coil capacity that makes inductive cell applicable for measurement of electrical conductivity of low conductive samples (specific conductance is less than 1S/m). The model can be used to calculate impedance of inductive cell for different characteristics of sample, materials and dimensions of cell without numerical solving of partial differential equations. Results of numerical simulation were verified by experiment for several devices with inductive cell. Some features that an engineer has to hold in mind while designing a conductometer based on inductive cell are discussed. Presented model can be useful for those who study inductively coupled plasma.

  3. Modelling Neurodegenerative Diseases Using Human Pluripotent Stem Cells

    DEFF Research Database (Denmark)

    Hall, Vanessa J.


    Neurodegenerative diseases are being modelled in-vitro using human patient-specific, induced pluripotent stem cells and transgenic embryonic stem cells to determine more about disease mechanisms, as well as to discover new treatments for patients. Current research in modelling Alzheimer’s disease......, frontotemporal dementia and Parkinson’s disease using pluripotent stem cells is described, along with the advent of gene-editing, which has been the complimentary tool for the field. Current methods used to model these diseases are predominantly dependent on 2D cell culture methods. Outcomes reveal that only...... that includes studying more complex 3D cell cultures, as well as accelerating aging of the neurons, may help to yield stronger phenotypes in the cultured cells. Thus, the use and application of pluripotent stem cells for modelling disease have already shown to be a powerful approach for discovering more about...

  4. Dynamic distribution and stem cell characteristics of Sox1-expressing cells in the cerebellar cortex

    Institute of Scientific and Technical Information of China (English)

    Joelle Alcock; Virginie Sottile


    Bergmann glia cells are a discrete radial glia population surrounding Purkinje cells in the cerebellar cortex. Al-though Bergmann glia are essential for the development and correct arborization of Purkinje cells, little is known about the regulation of this cell population after the developmental phase. In an effort to characterize this population at the molecular level, we have analyzed marker expression and established that adult Bergmann glia express Soxl, Sox2 and Sox9, a feature otherwise associated with neural stem cells (NSCs). In the present study, we have further analyzed the developmental pattern of Soxl-expressing cells in the developing cerebellum. We report that before be-coming restricted to the Purkinje cell layer, Soxl-positive cells are present throughout the immature tissue, and that these cells show characteristics of Bergmann glia progenitors. Our study shows that these progenitors express Soxl, Sox2 and Sox9, a signature maintained throughout cerebellar maturation into adulthood. When isolated in culture, the Soxl-expressing cerebellar population exhibited neurosphere-forming ability, NSC-marker characteristics, and demonstrated multipotency at the clonal level. Our results show that the Bergmann glia population expresses Soxl during cerebellar development, and that these cells can be isolated and show stem cell characteristics in vitro, sug-gesting that they could hold a broader potential than previously thought.

  5. Mathematical models in cell biology and cancer chemotherapy

    CERN Document Server

    Eisen, Martin


    The purpose of this book is to show how mathematics can be applied to improve cancer chemotherapy. Unfortunately, most drugs used in treating cancer kill both normal and abnormal cells. However, more cancer cells than normal cells can be destroyed by the drug because tumor cells usually exhibit different growth kinetics than normal cells. To capitalize on this last fact, cell kinetics must be studied by formulating mathematical models of normal and abnormal cell growth. These models allow the therapeutic and harmful effects of cancer drugs to be simulated quantitatively. The combined cell and drug models can be used to study the effects of different methods of administering drugs. The least harmful method of drug administration, according to a given criterion, can be found by applying optimal control theory. The prerequisites for reading this book are an elementary knowledge of ordinary differential equations, probability, statistics, and linear algebra. In order to make this book self-contained, a chapter on...

  6. Modeling the Chagas’ disease after stem cell transplantation (United States)

    Galvão, Viviane; Miranda, José Garcia Vivas


    A recent model for Chagas’ disease after stem cell transplantation is extended for a three-dimensional multi-agent-based model. The computational model includes six different types of autonomous agents: inflammatory cell, fibrosis, cardiomyocyte, proinflammatory cytokine tumor necrosis factor- α, Trypanosoma cruzi, and bone marrow stem cell. Only fibrosis is fixed and the other types of agents can move randomly through the empty spaces using the three-dimensional Moore neighborhood. Bone marrow stem cells can promote apoptosis in inflammatory cells, fibrosis regression and can differentiate in cardiomyocyte. T. cruzi can increase the number of inflammatory cells. Inflammatory cells and tumor necrosis factor- α can increase the quantity of fibrosis. Our results were compared with experimental data giving a fairly fit and they suggest that the inflammatory cells are important for the development of fibrosis.

  7. Interactions between airway epithelial cells and dendritic cells during viral infections using an in vitro co-culture model (United States)

    Rationale: Historically, single cell culture models have been limited in pathological and physiological relevance. A co-culture model of dendritic cells (DCs) and differentiated human airway epithelial cells was developed to examine potential interactions between these two cell t...

  8. Cell models lead to understanding of multi-cellular morphogenesis consisting of successive self-construction of cells. (United States)

    Honda, Hisao; Nagai, Tatsuzo


    Morphogenesis of multi-cellular organisms occurs through cell behaviours within a cell aggregate. Cell behaviours have been described using cell models involving equations of motion for cells. Cells in cell models construct shapes of the cell aggregate by themselves. Here, a history of cell models, the cell centre model and the vertex cell model, which we have constructed, are described. Furthermore, the application of these cell models is explained in detail. These cell models have been applied to transformation of cell aggregates to become spherical, formation of mammalian blastocysts and cell intercalation in elongating tissues. These are all elemental processes of morphogenesis and take place in succession during the whole developmental process. A chain of successive elemental processes leads to morphogenesis. Finally, we highlight that cell models are indispensable to understand the process whereby genes direct biological shapes.

  9. Modelling Rho GTPase biochemistry to predict collective cell migration (United States)

    Merchant, Brian; Feng, James

    The collective migration of cells, due to individual cell polarization and intercellular contact inhibition of locomotion, features prominently in embryogenesis and metastatic cancers. Existing methods for modelling collectively migrating cells tend to rely either on highly abstracted agent-based models, or on continuum approximations of the group. Both of these frameworks represent intercellular interactions such as contact inhibition of locomotion as hard-coded rules defining model cells. In contrast, we present a vertex-dynamics framework which predicts polarization and contact inhibition of locomotion naturally from an underlying model of Rho GTPase biochemistry and cortical mechanics. We simulate the interaction between many such model cells, and study how modulating Rho GTPases affects migratory characteristics of the group, in the context of long-distance collective migration of neural crest cells during embryogenesis.

  10. Stem Cells for Modeling and Therapy of Parkinson's Disease. (United States)

    Zhang, Qingxi; Chen, Wanling; Tan, Sheng; Lin, Tongxiang


    Parkinson's disease (PD) is the second most frequent neurodegenerative disease after Alzheimer's disease, which is characterized by a low level of dopamine being expressing in the striatum and a deterioration of dopaminergic neurons (DAn) in the substantia nigra pars compacta. Generation of PD-derived DAn, including differentiation of human embryonic stem cells, human neural stem cells, human-induced pluripotent stem cells, and direct reprogramming, provides an ideal tool to model PD, creating the possibility of mimicking key essential pathological processes and charactering single-cell changes in vitro. Furthermore, thanks to the understanding of molecular neuropathogenesis of PD and new advances in stem-cell technology, it is anticipated that optimal functionally transplanted DAn with targeted correction and transgene-free insertion will be generated for use in cell transplantation. This review elucidates stem-cell technology for modeling PD and offering desired safe cell resources for cell transplantation therapy.

  11. Diffusion and extrusion shape standing calcium gradients during ongoing parallel fiber activity in dendrites of Purkinje neurons. (United States)

    Schmidt, Hartmut; Arendt, Oliver; Eilers, Jens


    Synaptically induced calcium transients in dendrites of Purkinje neurons (PNs) play a key role in the induction of plasticity in the cerebellar cortex (Ito, Physiol Rev 81:1143-1195, 2001). Long-term depression at parallel fiber-PN synapses can be induced by stimulation paradigms that are associated with long-lasting (>1 min) calcium signals. These signals remain strictly localized (Eilers et al., Learn Mem 3:159-168, 1997), an observation that was rather unexpected, given the high concentration of the mobile endogenous calcium-binding proteins parvalbumin and calbindin in PNs (Fierro and Llano, J Physiol (Lond) 496:617-625, 1996; Kosaka et al., Exp Brain Res 93:483-491, 1993). By combining two-photon calcium imaging experiments in acute slices with numerical computer simulations, we found that significant calcium diffusion out of active branches indeed takes places. It is outweighed, however, by rapid and powerful calcium extrusion along the dendritic shaft. The close interplay of diffusion and extrusion defines the spread of calcium between active and inactive dendritic branches, forming a steep gradient in calcium with drop ranges of ~13 μm (interquartile range, 10-18 μm).

  12. Autistic-Like Behaviors, Oxidative Stress Status, and Histopathological Changes in Cerebellum of Valproic Acid Rat Model of Autism Are Improved by the Combined Extract of Purple Rice and Silkworm Pupae

    Directory of Open Access Journals (Sweden)

    Nartnutda Morakotsriwan


    Full Text Available Due to the crucial role of oxidative stress on the pathophysiology of autism and the concept of synergistic effect, the benefit of the combined extract of purple rice and silkworm pupae (AP1 for autism disorder was the focus. Therefore, we aimed to determine the effect of AP1 on autistic-like behaviors, oxidative stress status, and histopathological change of cerebellum in valproic acid (VPA rat model of autism. VPA was injected on postnatal day (PND 14 and the animals were orally given AP1 at doses of 50, 100, and 200 mg·kg−1 BW between PND 14 and PND 40. The autism-like behaviors were analyzed via hot-plate, rotarod, elevated plus-maze, learning, memory, and social behavior tests. Oxidative stress and the histological change in the cerebellum were assessed at the end of study. AP1 treated rats improved behaviors in all tests except that in hot-plate test. The improvement of oxidative stress and Purkinje cell loss was also observed in the cerebellum of VPA-treated rats. Our data suggest that AP1 partially reduced autism-like behaviors by improving oxidative stress and Purkinje cell loss. Further research is required to identify the active ingredients in AP1 and gender difference effect.

  13. Autistic-Like Behaviors, Oxidative Stress Status, and Histopathological Changes in Cerebellum of Valproic Acid Rat Model of Autism Are Improved by the Combined Extract of Purple Rice and Silkworm Pupae. (United States)

    Morakotsriwan, Nartnutda; Wattanathorn, Jintanaporn; Kirisattayakul, Woranan; Chaisiwamongkol, Kowit


    Due to the crucial role of oxidative stress on the pathophysiology of autism and the concept of synergistic effect, the benefit of the combined extract of purple rice and silkworm pupae (AP1) for autism disorder was the focus. Therefore, we aimed to determine the effect of AP1 on autistic-like behaviors, oxidative stress status, and histopathological change of cerebellum in valproic acid (VPA) rat model of autism. VPA was injected on postnatal day (PND) 14 and the animals were orally given AP1 at doses of 50, 100, and 200 mg·kg(-1) BW between PND 14 and PND 40. The autism-like behaviors were analyzed via hot-plate, rotarod, elevated plus-maze, learning, memory, and social behavior tests. Oxidative stress and the histological change in the cerebellum were assessed at the end of study. AP1 treated rats improved behaviors in all tests except that in hot-plate test. The improvement of oxidative stress and Purkinje cell loss was also observed in the cerebellum of VPA-treated rats. Our data suggest that AP1 partially reduced autism-like behaviors by improving oxidative stress and Purkinje cell loss. Further research is required to identify the active ingredients in AP1 and gender difference effect.

  14. Modeling the mechanics of cells in the cell-spreading process driven by traction forces (United States)

    Fang, Yuqiang; Lai, King W. C.


    Mechanical properties of cells and their mechanical interaction with the extracellular environments are main factors influencing cellular function, thus indicating the progression of cells in different disease states. By considering the mechanical interactions between cell adhesion molecules and the extracellular environment, we developed a cell mechanical model that can characterize the mechanical changes in cells during cell spreading. A cell model was established that consisted of various main subcellular components, including cortical cytoskeleton, nuclear envelope, actin filaments, intermediate filaments, and microtubules. We demonstrated the structural changes in subcellular components and the changes in spreading areas during cell spreading driven by traction forces. The simulation of nanoindentation tests was conducted by integrating the indenting force to the cell model. The force-indentation curve of the cells at different spreading states was simulated, and the results showed that cell stiffness increased with increasing traction forces, which were consistent with the experimental results. The proposed cell mechanical model provides a strategy to investigate the mechanical interactions of cells with the extracellular environments through the adhesion molecules and to reveal the cell mechanical properties at the subcellular level as cells shift from the suspended state to the adherent state.

  15. Cell-based modeling of cell-matrix interactions in angiogenesis

    Directory of Open Access Journals (Sweden)

    Merks Roeland M.H.


    Full Text Available The self-organization of endothelial cells into blood vessel networks and sprouts can be studied using computational, cell-based models. These take as input the behavior of individual, endothelial cells, as observed in experiments, and gives as output the resulting, collective behavior, i.e. the formation of shapes and tissue structures. Many cell-based models ignore the extracellular matrix, i.e., the fibrous or homogeneous materials that surround cells and gives tissue structural support. In this extended abstract, we highlight two approaches that we have taken to explore the role of the extracellular matrix in our cellular Potts models of blood vessel formation (angiogenesis: first we discuss a model considering chemical endothelial cell-matrix interactions, then we discuss a model that include mechanical cell-matrix interactions. We end by discussing some potential new directions.

  16. Device and materials modeling in PEM fuel cells

    CERN Document Server

    Promislow, Keith


    Device and Materials Modeling in PEM Fuel Cells is a specialized text that compiles the mathematical details and results of both device and materials modeling in a single volume. Proton exchange membrane (PEM) fuel cells will likely have an impact on our way of life similar to the integrated circuit. The potential applications range from the micron scale to large scale industrial production. Successful integration of PEM fuel cells into the mass market will require new materials and a deeper understanding of the balance required to maintain various operational states. This book contains articles from scientists who contribute to fuel cell models from both the materials and device perspectives. Topics such as catalyst layer performance and operation, reactor dynamics, macroscopic transport, and analytical models are covered under device modeling. Materials modeling include subjects relating to the membrane and the catalyst such as proton conduction, atomistic structural modeling, quantum molecular dynamics, an...


    Institute of Scientific and Technical Information of China (English)


    The advancement of a systematic investigation on the modeling of cylindrical alkaline cells is presented.Initial analysis utilizes thermodynamic and kinetic information to predict alkaline cell performance under low discharge rates.Subsequent modling has taken into consideration detailed information on the chemistry of electrode reactions,mass tranport of dissolved species,physical and chemical properties of the electrolyte and solid phases,and internal geonetry of cell systems.The model is capable of predicting alkaline cell performance under a variety of dicharge conditions.The model also provides information regarding internal cell changes during discharge.The model is the basis of a rational approach for the optimal design of cells.

  18. Modeling Of Proton Exchange Membrane Fuel Cell Systems

    DEFF Research Database (Denmark)

    Nielsen, Mads Pagh

    The objective of this doctoral thesis was to develop reliable steady-state and transient component models suitable to asses-, develop- and optimize proton exchange membrane (PEM) fuel cell systems. Several components in PEM fuel cell systems were characterized and modeled. The developed component...

  19. Unidirectional cell crawling model guided by extracellular cues. (United States)

    Wang, Zhanjiang; Geng, Yuxu


    Cell migration is a highly regulated and complex cellular process to maintain proper homeostasis for various biological processes. Extracellular environment was identified as the main affecting factors determining the direction of cell crawling. It was observed experimentally that the cell prefers migrating to the area with denser or stiffer array of microposts. In this article, an integrated unidirectional cell crawling model was developed to investigate the spatiotemporal dynamics of unidirectional cell migration, which incorporates the dominating intracellular biochemical processes, biomechanical processes and the properties of extracellular micropost arrays. The interpost spacing and the stiffness of microposts are taken into account, respectively, to study the mechanism of unidirectional cell locomotion and the guidance of extracellular influence cues on the direction of unidirectional cell crawling. The model can explain adequately the unidirectional crawling phenomena observed in experiments such as "spatiotaxis" and "durotaxis," which allows us to obtain further insights into cell migration.

  20. Modelling of tandem cell temperature coefficients

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, D.J. [National Renewable Energy Lab., Golden, CO (United States)


    This paper discusses the temperature dependence of the basic solar-cell operating parameters for a GaInP/GaAs series-connected two-terminal tandem cell. The effects of series resistance and of different incident solar spectra are also discussed.

  1. Modeling learning in brain stem and cerebellar sites responsible for VOR plasticity (United States)

    Quinn, K. J.; Didier, A. J.; Baker, J. F.; Peterson, B. W.


    A simple model of vestibuloocular reflex (VOR) function was used to analyze several hypotheses currently held concerning the characteristics of VOR plasticity. The network included a direct vestibular pathway and an indirect path via the cerebellum. An optimization analysis of this model suggests that regulation of brain stem sites is critical for the proper modification of VOR gain. A more physiologically plausible learning rule was also applied to this network. Analysis of these simulation results suggests that the preferred error correction signal controlling gain modification of the VOR is the direct output of the accessory optic system (AOS) to the vestibular nuclei vs. a signal relayed through the cerebellum via floccular Purkinje cells. The potential anatomical and physiological basis for this conclusion is discussed, in relation to our current understanding of the latency of the adapted VOR response.

  2. Mathematical modelling of cell aggregation in liver tissue engineering


    Green, John Edward E.


    A promising method for growing functional liver tissue in vitro involves culturing hepatocytes as spheroidal cell aggregates. In this thesis, we develop mathematical models of cell aggregation, and use them to determine how hepatocytes' interactions with the extracellular matrix (ECM) on which they are seeded, and with stellate cells, affect the process. Chapters 2-4 focus on the effect that cell-ECM coupling has on the aggregation process. We use a novel formulation that couples a mechani...

  3. Computation of inverse functions in a model of cerebellar and reflex pathways allows to control a mobile mechanical segment. (United States)

    Ebadzadeh, M; Tondu, B; Darlot, C


    The command and control of limb movements by the cerebellar and reflex pathways are modeled by means of a circuit whose structure is deduced from functional constraints. One constraint is that fast limb movements must be accurate although they cannot be continuously controlled in closed loop by use of sensory signals. Thus, the pathways which process the motor orders must contain approximate inverse functions of the bio-mechanical functions of the limb and of the muscles. This can be achieved by means of parallel feedback loops, whose pattern turns out to be comparable to the anatomy of the cerebellar pathways. They contain neural networks able to anticipate the motor consequences of the motor orders, modeled by artificial neural networks whose connectivity is similar to that of the cerebellar cortex. These networks learn the direct biomechanical functions of the limbs and muscles by means of a supervised learning process. Teaching signals calculated from motor errors are sent to the learning sites, as, in the cerebellum, complex spikes issued from the inferior olive are conveyed to the Purkinje cells by climbing fibers. Learning rules are deduced by a differential calculation, as classical gradient rules, and they account for the long term depression which takes place in the dendritic arborizations of the Purkinje cells. Another constraint is that reflexes must not impede voluntary movements while remaining at any instant ready to oppose perturbations. Therefore, efferent copies of the motor orders are sent to the interneurones of the reflexes, where they cancel the sensory-motor consequences of the voluntary movements. After learning, the model is able to drive accurately, both in velocity and position, angular movements of a rod actuated by two pneumatic McKibben muscles. Reflexes comparable to the myotatic and tendinous reflexes, and stabilizing reactions comparable to the cerebellar sensory-motor reactions, reduce efficiently the effects of perturbing torques

  4. New hybrid model of proton exchange membrane fuel cell

    Institute of Scientific and Technical Information of China (English)

    WANG Rui-min; CAO Guang-yi; ZHU Xin-jian


    Model and simulation are good tools for design optimization of fuel cell systems. This paper proposes a new hybrid model of proton exchange membrane fuel cell (PEMFC). The hybrid model includes physical component and black-box component. The physical component represents the well-known part of PEMFC, while artificial neural network (ANN) component estimates the poorly known part of PEMFC. The ANN model can compensate the performance of the physical model. This hybrid model is implemented on Matlab/Simulink software. The hybrid model shows better accuracy than that of the physical model and ANN model. Simulation results suggest that the hybrid model can be used as a suitable and accurate model for PEMFC.

  5. Optimization of the cell seeding density and modeling of cell growth and metabolism using the modified Gompertz model for microencapsulated animal cell culture. (United States)

    Wen-tao, Qi; Ying, Zhang; Juan, Ma; Xin, Guo; Yu-bing, Xie; Wei, Wang; Xiaojun, Ma


    Cell microencapsulation is one of the promising strategies for the in vitro production of proteins or in vivo delivery of therapeutic products. In order to design and fabricate the optimized microencapsulated cell system, the Gompertz model was applied and modified to describe the growth and metabolism of microencapsulated cell, including substrate consumption and product formation. The Gompertz model successfully described the cell growth kinetics and the modified Gompertz models fitted the substrate consumption and product formation well. It was demonstrated that the optimal initial cell seeding density was about 4-5 x 10(6) cells/mL of microcapsule, in terms of the maximum specific growth rate, the glucose consumption potential and the product formation potential calculated by the Gompertz and modified Gompertz models. Modeling of cell growth and metabolism in microcapsules provides a guideline for optimizing the culture of microencapsulated cells.

  6. Dissecting Germ Cell Metabolism through Network Modeling.

    Directory of Open Access Journals (Sweden)

    Leanne S Whitmore

    Full Text Available Metabolic pathways are increasingly postulated to be vital in programming cell fate, including stemness, differentiation, proliferation, and apoptosis. The commitment to meiosis is a critical fate decision for mammalian germ cells, and requires a metabolic derivative of vitamin A, retinoic acid (RA. Recent evidence showed that a pulse of RA is generated in the testis of male mice thereby triggering meiotic commitment. However, enzymes and reactions that regulate this RA pulse have yet to be identified. We developed a mouse germ cell-specific metabolic network with a curated vitamin A pathway. Using this network, we implemented flux balance analysis throughout the initial wave of spermatogenesis to elucidate important reactions and enzymes for the generation and degradation of RA. Our results indicate that primary RA sources in the germ cell include RA import from the extracellular region, release of RA from binding proteins, and metabolism of retinal to RA. Further, in silico knockouts of genes and reactions in the vitamin A pathway predict that deletion of Lipe, hormone-sensitive lipase, disrupts the RA pulse thereby causing spermatogenic defects. Examination of other metabolic pathways reveals that the citric acid cycle is the most active pathway. In addition, we discover that fatty acid synthesis/oxidation are the primary energy sources in the germ cell. In summary, this study predicts enzymes, reactions, and pathways important for germ cell commitment to meiosis. These findings enhance our understanding of the metabolic control of germ cell differentiation and will help guide future experiments to improve reproductive health.

  7. Three-dimensional cell culture models for investigating human viruses. (United States)

    He, Bing; Chen, Guomin; Zeng, Yi


    Three-dimensional (3D) culture models are physiologically relevant, as they provide reproducible results, experimental flexibility and can be adapted for high-throughput experiments. Moreover, these models bridge the gap between traditional two-dimensional (2D) monolayer cultures and animal models. 3D culture systems have significantly advanced basic cell science and tissue engineering, especially in the fields of cell biology and physiology, stem cell research, regenerative medicine, cancer research, drug discovery, and gene and protein expression studies. In addition, 3D models can provide unique insight into bacteriology, virology, parasitology and host-pathogen interactions. This review summarizes and analyzes recent progress in human virological research with 3D cell culture models. We discuss viral growth, replication, proliferation, infection, virus-host interactions and antiviral drugs in 3D culture models.

  8. Modelling of Yeast Mating Reveals Robustness Strategies for Cell-Cell Interactions.

    Directory of Open Access Journals (Sweden)

    Weitao Chen


    Full Text Available Mating of budding yeast cells is a model system for studying cell-cell interactions. Haploid yeast cells secrete mating pheromones that are sensed by the partner which responds by growing a mating projection toward the source. The two projections meet and fuse to form the diploid. Successful mating relies on precise coordination of dynamic extracellular signals, signaling pathways, and cell shape changes in a noisy background. It remains elusive how cells mate accurately and efficiently in a natural multi-cell environment. Here we present the first stochastic model of multiple mating cells whose morphologies are driven by pheromone gradients and intracellular signals. Our novel computational framework encompassed a moving boundary method for modeling both a-cells and α-cells and their cell shape changes, the extracellular diffusion of mating pheromones dynamically coupled with cell polarization, and both external and internal noise. Quantification of mating efficiency was developed and tested for different model parameters. Computer simulations revealed important robustness strategies for mating in the presence of noise. These strategies included the polarized secretion of pheromone, the presence of the α-factor protease Bar1, and the regulation of sensing sensitivity; all were consistent with data in the literature. In addition, we investigated mating discrimination, the ability of an a-cell to distinguish between α-cells either making or not making α-factor, and mating competition, in which multiple a-cells compete to mate with one α-cell. Our simulations were consistent with previous experimental results. Moreover, we performed a combination of simulations and experiments to estimate the diffusion rate of the pheromone a-factor. In summary, we constructed a framework for simulating yeast mating with multiple cells in a noisy environment, and used this framework to reproduce mating behaviors and to identify strategies for robust cell-cell

  9. Proton exchange membrane fuel cells modeling

    CERN Document Server

    Gao, Fengge; Miraoui, Abdellatif


    The fuel cell is a potential candidate for energy storage and conversion in our future energy mix. It is able to directly convert the chemical energy stored in fuel (e.g. hydrogen) into electricity, without undergoing different intermediary conversion steps. In the field of mobile and stationary applications, it is considered to be one of the future energy solutions.Among the different fuel cell types, the proton exchange membrane (PEM) fuel cell has shown great potential in mobile applications, due to its low operating temperature, solid-state electrolyte and compactness.This book pre

  10. Recent Advances in Enzymatic Fuel Cells: Experiments and Modeling

    Directory of Open Access Journals (Sweden)

    Ivan Ivanov


    Full Text Available Enzymatic fuel cells convert the chemical energy of biofuels into electrical energy. Unlike traditional fuel cell types, which are mainly based on metal catalysts, the enzymatic fuel cells employ enzymes as catalysts. This fuel cell type can be used as an implantable power source for a variety of medical devices used in modern medicine to administer drugs, treat ailments and monitor bodily functions. Some advantages in comparison to conventional fuel cells include a simple fuel cell design and lower cost of the main fuel cell components, however they suffer from severe kinetic limitations mainly due to inefficiency in electron transfer between the enzyme and the electrode surface. In this review article, the major research activities concerned with the enzymatic fuel cells (anode and cathode development, system design, modeling by highlighting the current problems (low cell voltage, low current density, stability will be presented.

  11. A Model of Dendritic Cell Therapy for Melanoma

    Directory of Open Access Journals (Sweden)

    Ami eRadunskaya


    Full Text Available Dendritic cells are a promising immunotherapy tool for boosting an individual's antigen specific immune response to cancer. We develop a mathematical model using differential and delay-differential equations to describe the interactions between dendritic cells, effector-immune cells and tumor cells. We account for the trafficking of immune cells between lymph, blood, and tumor compartments. Our model reflects experimental results both for dendritic-cell trafficking and for immune suppression of tumor growth in mice. In addition, in silico experiments suggest more effective immunotherapy treatment protocols can be achieved by modifying dose location and schedule. A sensitivity analysis of the model reveals which patient-specific parameters have the greatest impact on treatment efficacy.

  12. Stochastic Model of Clogging in a Microfluidic Cell Sorter (United States)

    Fai, Thomas; Rycroft, Chris


    Microfluidic devices for sorting cells by deformability show promise for various medical purposes, e.g. detecting sickle cell anemia and circulating tumor cells. One class of such devices consists of a two-dimensional array of narrow channels, each column containing several identical channels in parallel. Cells are driven through the device by an applied pressure or flow rate. Such devices allows for many cells to be sorted simultaneously, but cells eventually clog individual channels and change the device properties in an unpredictable manner. In this talk, we propose a stochastic model for the failure of such microfluidic devices by clogging and present preliminary theoretical and computational results. The model can be recast as an ODE that exhibits finite time blow-up under certain conditions. The failure time distribution is investigated analytically in certain limiting cases, and more realistic versions of the model are solved by computer simulation.

  13. Modelling familial dysautonomia in human induced pluripotent stem cells. (United States)

    Lee, Gabsang; Studer, Lorenz


    Induced pluripotent stem (iPS) cells have considerable promise as a novel tool for modelling human disease and for drug discovery. While the generation of disease-specific iPS cells has become routine, realizing the potential of iPS cells in disease modelling poses challenges at multiple fronts. Such challenges include selecting a suitable disease target, directing the fate of iPS cells into symptom-relevant cell populations, identifying disease-related phenotypes and showing reversibility of such phenotypes using genetic or pharmacological approaches. Finally, the system needs to be scalable for use in modern drug discovery. Here, we will discuss these points in the context of modelling familial dysautonomia (FD, Riley-Day syndrome, hereditary sensory and autonomic neuropathy III (HSAN-III)), a rare genetic disorder in the peripheral nervous system. We have demonstrated three disease-specific phenotypes in FD-iPS-derived cells that can be partially rescued by treating cells with the plant hormone kinetin. Here, we will discuss how to use FD-iPS cells further in high throughput drug discovery assays, in modelling disease severity and in performing mechanistic studies aimed at understanding disease pathogenesis. FD is a rare disease but represents an important testing ground for exploring the potential of iPS cell technology in modelling and treating human disease.

  14. Modelling cell polarization driven by synthetic spatially graded Rac activation.

    Directory of Open Access Journals (Sweden)

    William R Holmes

    Full Text Available The small GTPase Rac is known to be an important regulator of cell polarization, cytoskeletal reorganization, and motility of mammalian cells. In recent microfluidic experiments, HeLa cells endowed with appropriate constructs were subjected to gradients of the small molecule rapamycin leading to synthetic membrane recruitment of a Rac activator and direct graded activation of membrane-associated Rac. Rac activation could thus be triggered independent of upstream signaling mechanisms otherwise responsible for transducing activating gradient signals. The response of the cells to such stimulation depended on exceeding a threshold of activated Rac. Here we develop a minimal reaction-diffusion model for the GTPase network alone and for GTPase-phosphoinositide crosstalk that is consistent with experimental observations for the polarization of the cells. The modeling suggests that mutual inhibition is a more likely mode of cell polarization than positive feedback of Rac onto its own activation. We use a new analytical tool, Local Perturbation Analysis, to approximate the partial differential equations by ordinary differential equations for local and global variables. This method helps to analyze the parameter space and behaviour of the proposed models. The models and experiments suggest that (1 spatially uniform stimulation serves to sensitize a cell to applied gradients. (2 Feedback between phosphoinositides and Rho GTPases sensitizes a cell. (3 Cell lengthening/flattening accompanying polarization can increase the sensitivity of a cell and stabilize an otherwise unstable polarization.

  15. A multi-phenotypic cancer model with cell plasticity. (United States)

    Zhou, Da; Wang, Yue; Wu, Bin


    The conventional cancer stem cell (CSC) theory indicates a hierarchy of CSCs and non-stem cancer cells (NSCCs), that is, CSCs can differentiate into NSCCs but not vice versa. However, an alternative paradigm of CSC theory with reversible cell plasticity among cancer cells has received much attention very recently. Here we present a generalized multi-phenotypic cancer model by integrating cell plasticity with the conventional hierarchical structure of cancer cells. We prove that under very weak assumption, the nonlinear dynamics of multi-phenotypic proportions in our model has only one stable steady state and no stable limit cycle. This result theoretically explains the phenotypic equilibrium phenomena reported in various cancer cell lines. Furthermore, according to the transient analysis of our model, it is found that cancer cell plasticity plays an essential role in maintaining the phenotypic diversity in cancer especially during the transient dynamics. Two biological examples with experimental data show that the phenotypic conversions from NCSSs to CSCs greatly contribute to the transient growth of CSCs proportion shortly after the drastic reduction of it. In particular, an interesting overshooting phenomenon of CSCs proportion arises in three-phenotypic example. Our work may pave the way for modeling and analyzing the multi-phenotypic cell population dynamics with cell plasticity.

  16. [Development of human embryonic stem cell model for toxicity evaluation]. (United States)

    Yu, Guang-yan; Cao, Tong; Ouyang, Hong-wei; Peng, Shuang-qing; Deng, Xu-liang; Li, Sheng-lin; Liu, He; Zou, Xiao-hui; Fu, Xin; Peng, Hui; Wang, Xiao-ying; Zhan, Yuan


    The current international standard for toxicity screening of biomedical devices and materials recommend the use of immortalized cell lines because of their homogeneous morphologies and infinite proliferation which provide good reproducibility for in vitro cytotoxicity screening. However, most of the widely used immortalized cell lines are derived from animals and may not be representative of normal human cell behavior in vivo, in particular in terms of the cytotoxic and genotoxic response. Therefore, It is vital to develop a model for toxicity evaluation. In our studies, two Chinese human embryonic stem cell (hESC) lines as toxicity model were established. hESC derived tissue/organ cell model for tissue/organ specific toxicity evaluation were developed. The efficiency and accuracy of using hESC model for cytoxicity, embryotoxicity and genotoxicity evaluation were confirmed. The results indicated that hESCs might be good tools for toxicity testing and biosafety evaluation in vitro.

  17. Modelling Spread of Oncolytic Viruses in Heterogeneous Cell Populations (United States)

    Ellis, Michael; Dobrovolny, Hana


    One of the most promising areas in current cancer research and treatment is the use of viruses to attack cancer cells. A number of oncolytic viruses have been identified to date that possess the ability to destroy or neutralize cancer cells while inflicting minimal damage upon healthy cells. Formulation of predictive models that correctly describe the evolution of infected tumor systems is critical to the successful application of oncolytic virus therapy. A number of different models have been proposed for analysis of the oncolytic virus-infected tumor system, with approaches ranging from traditional coupled differential equations such as the Lotka-Volterra predator-prey models, to contemporary modeling frameworks based on neural networks and cellular automata. Existing models are focused on tumor cells and the effects of virus infection, and offer the potential for improvement by including effects upon normal cells. We have recently extended the traditional framework to a 2-cell model addressing the full cellular system including tumor cells, normal cells, and the impacts of viral infection upon both populations. Analysis of the new framework reveals complex interaction between the populations and potential inability to simultaneously eliminate the virus and tumor populations.

  18. Triple co-culture cell model as an in vitro model for oral particulate vaccine systems

    DEFF Research Database (Denmark)

    Nielsen, Line Hagner; De Rossi, C.; Lehr, C-M.

    A triple co-culture cell model of Caco-2 cells, dendritic cells and macrophages (Figure 1) has previously been developed for studying intestinal permeability in a state of inflammation [1],[2]. The aim of this study was to investigate the applicability of this cell model for testing...... the model antigen ovalbumin was spray dried to obtain a particulate vaccine model system for testing in the cell model. The precursors were shown to form cubosomes when dispersed in aqueous medium, and was therefore used as the vaccine formulation for testing on the co-cultures. After 11 days, the TEER...... values of the co-cultures were found to be 860-1340 Ω∙cm2; the formulations were incubated with the co-cultures at this time point. From confocal microscopy images, it was observed that the THP-1 cells (macrophages) migrated into the overlying Caco-2 cell monolayer when the co-cultures were incubated...

  19. Analyzing electrical activities of pancreatic β cells using mathematical models. (United States)

    Cha, Chae Young; Powell, Trevor; Noma, Akinori


    Bursts of repetitive action potentials are closely related to the regulation of glucose-induced insulin secretion in pancreatic β cells. Mathematical studies with simple β-cell models have established the central principle that the burst-interburst events are generated by the interaction between fast membrane excitation and slow cytosolic components. Recently, a number of detailed models have been developed to simulate more realistic β cell activity based on expanded findings on biophysical characteristics of cellular components. However, their complex structures hinder our intuitive understanding of the underlying mechanisms, and it is becoming more difficult to dissect the role of a specific component out of the complex network. We have recently developed a new detailed model by incorporating most of ion channels and transporters recorded experimentally (the Cha-Noma model), yet the model satisfies the charge conservation law and reversible responses to physiological stimuli. Here, we review the mechanisms underlying bursting activity by applying mathematical analysis tools to representative simple and detailed models. These analyses include time-based simulation, bifurcation analysis and lead potential analysis. In addition, we introduce a new steady-state I-V (ssI-V) curve analysis. We also discuss differences in electrical signals recorded from isolated single cells or from cells maintaining electrical connections within multi-cell preparations. Towards this end, we perform simulations with our detailed pancreatic β-cell model.

  20. Examination of 1D Solar Cell Model Limitations Using 3D SPICE Modeling: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, W. E.; Olson, J. M.; Geisz, J. F.; Friedman, D. J.


    To examine the limitations of one-dimensional (1D) solar cell modeling, 3D SPICE-based modeling is used to examine in detail the validity of the 1D assumptions as a function of sheet resistance for a model cell. The internal voltages and current densities produced by this modeling give additional insight into the differences between the 1D and 3D models.

  1. Modeling circadian clock-cell cycle interaction effects on cell population growth rates. (United States)

    El Cheikh, R; Bernard, S; El Khatib, N


    The circadian clock and the cell cycle are two tightly coupled oscillators. Recent analytical studies have shown counter-intuitive effects of circadian gating of the cell cycle on growth rates of proliferating cells which cannot be explained by a molecular model or a population model alone. In this work, we present a combined molecular-population model that studies how coupling the circadian clock to the cell cycle, through the protein WEE1, affects a proliferating cell population. We show that the cell cycle can entrain to the circadian clock with different rational period ratios and characterize multiple domains of entrainment. We show that coupling increases the growth rate for autonomous periods of the cell cycle around 24 h and above 48 h. We study the effect of mutation of circadian genes on the growth rate of cells and show that disruption of the circadian clock can lead to abnormal proliferation. Particularly, we show that Cry 1, Cry 2 mutations decrease the growth rate of cells, Per 2 mutation enhances it and Bmal 1 knockout increases it for autonomous periods of the cell cycle less than 21 h and decreases it elsewhere. Combining a molecular model to a population model offers new insight on the influence of the circadian clock on the growth of a cell population. This can help chronotherapy which takes benefits of physiological rhythms to improve anti-cancer efficacy and tolerance to drugs by administering treatments at a specific time of the day.

  2. A three-dimensional finite element model for the mechanics of cell-cell interactions. (United States)

    Viens, Denis; Brodland, G Wayne


    Technical challenges, including significant ones associated with cell rearrangement, have hampered the development of three-dimensional finite element models for the mechanics of embryonic cells. These challenges have been overcome by a new formulation in which the contents of each cell, assumed to have a viscosity mu, are modeled using a system of orthogonal dashpots. This approach overcomes a stiffening artifact that affects more traditional models, in which space-filling viscous elements are used to model the cytoplasm. Cells are assumed to be polyhedral in geometry, and each n-sided polygonal face is subdivided into n triangles with a common node at the face center so that it needs not remain flat. A constant tension gamma is assumed to act along each cell-cell interface, and cell rearrangements occur through one of two complementary topological transformations. The formulation predicts mechanical interactions between pairs of similar or dissimilar cells that are consistent with experiments, two-dimensional simulations, contact angle theory, and intracellular pressure calculations. Simulations of the partial engulfment of one tissue type by another show that the formulation is able to model aggregates of several hundred cells without difficulty. Simulations carried out using this formulation suggest new experimental approaches for measuring cell surface tensions and interfacial tensions. The formulation holds promise as a tool for gaining insight into the mechanics of isolated or aggregated embryonic cells and for the design and interpretation of experiments that involve them.

  3. Schelling model of cell segregation based only on local information (United States)

    Nielsen, Alexander Valentin; Gade, Annika Lund; Juul, Jeppe; Strandkvist, Charlotte


    While biological studies suggest that motility of cells is involved in cell segregation, few computational models have investigated this mechanism. We apply a simple Schelling model, modified to reflect biological conditions, demonstrating how differences in cell motility arising exclusively from differences in the composition of the local environment can be sufficient to drive segregation. The work presented here demonstrates that the segregation behavior observed in the original Schelling model is robust to a relaxation of the requirement for global information and that the Schelling model may yield insight in the context of biological systems. In the model, the time course of cell segregation follows a power law in accord with experimental observations and previous work.

  4. Muse cells and induced pluripotent stem cell: implication of the elite model. (United States)

    Kitada, Masaaki; Wakao, Shohei; Dezawa, Mari


    Induced pluripotent stem (iPS) cells have attracted a great deal attention as a new pluripotent stem cell type that can be generated from somatic cells, such as fibroblasts, by introducing the transcription factors Oct3/4, Sox2, Klf4, and c-Myc. The mechanism of generation, however, is not fully understood. Two mechanistic theories have been proposed; the stochastic model purports that every cell type has the potential to be reprogrammed to become an iPS cell and the elite model proposes that iPS cell generation occurs only from a subset of cells. Some reports have provided theoretical support for the stochastic model, but a recent publication demonstrated findings that support the elite model, and thus the mechanism of iPS cell generation remains under debate. To enhance our understanding of iPS cells, it is necessary to clarify the properties of the original cell source, i.e., the components of the original populations and the potential of each population to become iPS cells. In this review, we discuss the two theories and their implications in iPS cell research.

  5. Tomato fruit growth : integrating cell division, cell growth and endoreduplication by experimentation and modelling

    NARCIS (Netherlands)

    Fanwoua, J.


    Keywords: cell division, cell growth, cell endoreduplication, fruit growth, genotype, G×E interaction, model, tomato. Fruit size is a major component of fruit yield and quality of many crops. Variations in fruit size can be tremendous due to genotypic and environmental factors. The mechanisms

  6. Entrainability of cell cycle oscillator models with exponential growth of cell mass. (United States)

    Nakao, Mitsuyuki; Enkhkhudulmur, Tsog-Erdene; Katayama, Norihiro; Karashima, Akihiro


    Among various aspects of cell cycle, understanding synchronization mechanism of cell cycle is important because of the following reasons. (1)Cycles of cell assembly should synchronize to form an organ. (2) Synchronizing cell cycles are required to experimental analysis of regulatory mechanisms of cell cycles. (3) Cell cycle has a distinct phase relationship with the other biological rhythms such as circadian rhythm. However, forced as well as mutual entrainment mechanisms are not clearly known. In this study, we investigated entrainability of cell cycle models of yeast cell under the periodic forcing to both of the cell mass and molecular dynamics. Dynamics of models under study involve the cell mass growing exponentially. In our result, they are shown to allow only a limited frequency range for being entrained by the periodic forcing. In contrast, models with linear growth are shown to be entrained in a wider frequency range. It is concluded that if the cell mass is included in the cell cycle regulation, its entrainability is sensitive to a shape of growth curve assumed in the model.

  7. Modeling selective elimination of quiescent cancer cells from bone marrow. (United States)

    Cavnar, Stephen P; Rickelmann, Andrew D; Meguiar, Kaille F; Xiao, Annie; Dosch, Joseph; Leung, Brendan M; Cai Lesher-Perez, Sasha; Chitta, Shashank; Luker, Kathryn E; Takayama, Shuichi; Luker, Gary D


    Patients with many types of malignancy commonly harbor quiescent disseminated tumor cells in bone marrow. These cells frequently resist chemotherapy and may persist for years before proliferating as recurrent metastases. To test for compounds that eliminate quiescent cancer cells, we established a new 384-well 3D spheroid model in which small numbers of cancer cells reversibly arrest in G1/G0 phase of the cell cycle when cultured with bone marrow stromal cells. Using dual-color bioluminescence imaging to selectively quantify viability of cancer and stromal cells in the same spheroid, we identified single compounds and combination treatments that preferentially eliminated quiescent breast cancer cells but not stromal cells. A treatment combination effective against malignant cells in spheroids also eliminated breast cancer cells from bone marrow in a mouse xenograft model. This research establishes a novel screening platform for therapies that selectively target quiescent tumor cells, facilitating identification of new drugs to prevent recurrent cancer. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  8. Electrophysiologic effects of a short-chain acyl carnitine, L-propionylcarnitine, on isolated canine Purkinje fibers. (United States)

    Aomine, M; Nobe, S; Arita, M


    The effects of L-propionylcarnitine (PC), a derivative of L-carnitine, on action potentials of canine Purkinje fibers in vitro, were studied under acidic conditions (pH 6.9), using conventional microelectrode techniques. The concentrations of 10(-5) M to 3 X 10(-3) M had no significant effect on action potential amplitude, maximal upstroke velocity of phase 0, and resting potential. However, higher concentrations of PC (10(-2) M and 3 X 10(-2) M) decreased some of these action potential parameters and such high concentrations of PC consistently prolonged the action potential duration (APD), most of which was attributed to the lengthening of phase 3. Under hypoxic conditions (PO2 less than or equal to 40 mm Hg) the drug (10(-2) M) also lengthened the APD with eventual cancellation of the hypoxia-induced shortening in the APD. The drug also prolonged the APD of slow response with a slight decrease in Vmax. In addition, PC significantly (p less than 0.05) depolarized the maximal diastolic potential of the fibers only at low [K+]o (less than or equal to 2.7 mM) and not at high [K+]o (greater than or equal to 5.4 mM). These observations suggest that the PC-induced prolongation of APD is, at least in part, due to a decrease in membrane K+ conductance, an effect partly shared with other amphiphilic intermediates of lipid metabolism, such as palmitylcarnitine or lysophosphatidylcholine.

  9. Modeling neurodegenerative diseases with patient-derived induced pluripotent cells

    DEFF Research Database (Denmark)

    Poon, Anna; Zhang, Yu; Chandrasekaran, Abinaya


    patient-specific induced pluripotent stem cells (iPSCs) and isogenic controls generated using CRISPR-Cas9 mediated genome editing. The iPSCs are self-renewable and capable of being differentiated into the cell types affected by the diseases. These in vitro models based on patient-derived iPSCs provide...... the possibilities of generating three-dimensional (3D) models using the iPSCs-derived cells and compare their advantages and disadvantages to conventional two-dimensional (2D) models....

  10. Effect of endothelial progenitor cell on hematopoietic reconstitution in allogeneic hematopoietic stem cell transplantation mouse model

    Institute of Scientific and Technical Information of China (English)



    Objective To examine the effects of endothelial progenitor cell (EPC) on hematopoietic reconsititution in allogeneic hematopoietic stem cell transplantation (alloHSCT) mouse model.Methods Allo-HSCT mouse model was established with condition of BU/CY,in which C57BL/6 (H-2b) and BABL/c (H-2d) mice were used

  11. Analysis of initial cell spreading using mechanistic contact formulations for a deformable cell model.

    Directory of Open Access Journals (Sweden)

    Tim Odenthal

    Full Text Available Adhesion governs to a large extent the mechanical interaction between a cell and its microenvironment. As initial cell spreading is purely adhesion driven, understanding this phenomenon leads to profound insight in both cell adhesion and cell-substrate interaction. It has been found that across a wide variety of cell types, initial spreading behavior universally follows the same power laws. The simplest cell type providing this scaling of the radius of the spreading area with time are modified red blood cells (RBCs, whose elastic responses are well characterized. Using a mechanistic description of the contact interaction between a cell and its substrate in combination with a deformable RBC model, we are now able to investigate in detail the mechanisms behind this universal power law. The presented model suggests that the initial slope of the spreading curve with time results from a purely geometrical effect facilitated mainly by dissipation upon contact. Later on, the spreading rate decreases due to increasing tension and dissipation in the cell's cortex as the cell spreads more and more. To reproduce this observed initial spreading, no irreversible deformations are required. Since the model created in this effort is extensible to more complex cell types and can cope with arbitrarily shaped, smooth mechanical microenvironments of the cells, it can be useful for a wide range of investigations where forces at the cell boundary play a decisive role.

  12. Aging and Immortality in a Cell Proliferation Model

    CERN Document Server

    Antal, T; Trugman, S A; Redner, S


    We investigate a model of cell division in which the length of telomeres within the cell regulate their proliferative potential. At each cell division the ends of linear chromosomes change and a cell becomes senescent when one or more of its telomeres become shorter than a critical length. In addition to this systematic shortening, exchange of telomere DNA between the two daughter cells can occur at each cell division. We map this telomere dynamics onto a biased branching diffusion process with an absorbing boundary condition whenever any telomere reaches the critical length. As the relative effects of telomere shortening and cell division are varied, there is a phase transition between finite lifetime and infinite proliferation of the cell population. Using simple first-passage ideas, we quantify the nature of this transition.

  13. Induced pluripotent stem cells and neurological disease models. (United States)

    Cai, Sa; Chan, Ying-Shing; Shum, Daisy Kwok-Yan


    The availability of human stem cells heralds a new era for in vitro cell-based modeling of neurodevelopmental and neurodegenerative diseases. Adding to the excitement is the discovery that somatic cells of patients can be reprogrammed to a pluripotent state from which neural lineage cells that carry the disease genotype can be derived. These in vitro cell-based models of neurological diseases hold promise for monitoring of disease initiation and progression, and for testing of new drug treatments on the patient-derived cells. In this review, we focus on the prospective applications of different stem cell types for disease modeling and drug screening. We also highlight how the availability of patient-specific induced pluripotent stem cells (iPS cells) offers a unique opportunity for studying and modeling human neurodevelopmental and neurodegenerative diseases in vitro and for testing small molecules or other potential therapies for these disorders. Finally, the limitations of this technology from the standpoint of reprogramming efficiency and therapeutic safety are discussed.

  14. Role of His-Purkinje System in Ventricular Arrhythmias%希氏-浦肯野系统和室性心律失常

    Institute of Scientific and Technical Information of China (English)

    周旭; 杨新春


    Recently the His-Purkinje system has been found to play an important role in the genesis of ventricular arrhythmias. The anatomic and cellular electrophysiologic complexity of the left ventricular conduction system appears to favor reentrant ventricular tachycardia in both diseased and healthy hearts. Newer discoveries strongly suggest the Purkinje system as the cause of ventricular arrhythmias in patients with short-coupled premature ventricular complexes and in those with catecholaminergic polymorphous ventricular tachycardia. With understanding of mechanisms related to His-Purkinje system and ventricular arrhythmias, many cardiac arrhythmias appears to involve the ventricular specialized conduction system and may be treated with catheter ablation.%近期研究提示希氏-浦肯野系统与室性心律失常的发生关系密切.作为左室的特殊传导组织,希氏-浦肯野系统的解剖与电生理特点,使其在正常或病理情况下易于参与折返型心律失常形成.目前资料提示浦肯野系统病变是短联律间期室性早搏相关心律失常和儿茶酚胺敏感性多形性室性心动过速的原因.随着对希氏-浦肯野系统与室性心律失常关系的认识,导管消融可作为此类心律失常的治疗途径.

  15. Modeling cell-matrix traction forces in Keratinocyte colonies (United States)

    Banerjee, Shiladitya


    Crosstalk between cell-cell and cell-matrix adhesions plays an essential role in the mechanical function of tissues. The traction forces exerted by cohesive keratinocyte colonies with strong cell-cell adhesions are mostly concentrated at the colony periphery. In contrast, for weak cadherin-based intercellular adhesions, individual cells in a colony interact with their matrix independently, with a disorganized distribution of traction forces extending throughout the colony. In this talk I will present a minimal physical model of the colony as contractile elastic media linked by springs and coupled to an elastic substrate. The model captures the spatial distribution of traction forces seen in experiments. For cell colonies with strong cell-cell adhesions, the total traction force of the colony measured in experiments is found to scale with the colony's geometrical size. This scaling suggests the emergence of an effective surface tension of magnitude comparable to that measured for non-adherent, three-dimensional cell aggregates. The physical model supports the scaling and indicates that the surface tension may be controlled by acto-myosin contractility. Supported by the NSF through grant DMR-1004789. This work was done in collaboration with Aaron F. Mertz, Eric R. Dufresne and Valerie Horsley (Yale University) and M. Cristina Marchetti (Syracuse University).

  16. Two-dimension tissue growth model based on circular granular cells for cells with small overlap

    CERN Document Server

    Viridi, Sparisoma; Aprianti, Devi; Haris, Luman; Haryanto, Freddy


    Tissue growth can be modeled in two dimension by only using circular granular cells, which can grow and produce child. Linear spring-dashpot model is used to bind the cells with a cut-off interaction range of 1.1 times sum of radii of interacted cells. Simulation steps must be divided into explicit and implicit ones due to cell growing stage and cell position rearrangement. This division is aimed to avoid simulation problem. Only in the explicit steps time changes is performed. Large cells overlap is chosen as termination condition of tissue growth. Only some cells configuration can growth to infinite time without encountering the large cells overlap. These configurations, and the other also, are presented in this work.

  17. A Coarse Estimation of Cell Size Region from a Mesoscopic Stochastic Cell Cycle Model (United States)

    Yi, Ming; Jia, Ya; Liu, Quan; Zhu, Chun-Lian; Yang, Li-Jian


    Based on a deterministic cell cycle model of fission yeast, the effects of the finite cell size on the cell cycle regulation in wee1- cdc25Δ double mutant type are numerically studied by using of the chemical Langevin equations. It is found that at a certain region of cell size, our numerical results from the chemical Langevin equations are in good qualitative agreement with the experimental observations. The two resettings to the G2 phase from early stages of mitosis can be induced under the moderate cell size. The quantized cycle times can be observed during such a cell size region. Therefore, a coarse estimation of cell size is obtained from the mesoscopic stochastic cell cycle model.

  18. A Coarse Estimation of Cell Size Region from a Mesoscopic Stochastic Cell Cycle Model

    Institute of Scientific and Technical Information of China (English)

    YI Ming; JIA Ya; LIU Quan; ZHU Chun-Lian; YANG Li-Jian


    Based on a deterministic cell cycle model of fission yeast, the effects of the finite cell size on the cell cycle regulation in wee1- cdc25△ double mutant type are numerically studied by using of the chemical Langevin equations. It is found that at a certain region of cell size, our numerical results from the chemical Langevin equations are in good qualitative agreement with the experimental observations. The two resettings to the G2 phase from early stages of mitosis can be induced under the moderate cell size. The quantized cycle times can be observed during such a cell size region. Therefore, a coarse estimation of cell size is obtained from the mesoscopic stochastic cell cycle model.

  19. Pluripotent Stem Cells Models for Huntington's Disease: Prospects and Challenges

    Institute of Scientific and Technical Information of China (English)

    Richard L. Carter; Anthony W.S. Chan


    Pluripotent cellular models have shown great promise in the study of a number of neurological disorders.Several advantages of using a stem cell model include the potential for cells to derive disease relevant neuronal cell types,providing a system for researchers to monitor disease progression during neurogenesis,along with serving as a platform for drug discovery.A number of stem cell derived models have been employed to establish in vitro research models of Huntington's disease that can be used to investigate cellular pathology and screen for drug and cell-based therapies.Although some progress has been made,there are a number of challenges and limitations that must be overcome before the true potential of this research strategy is achieved,In this article we review current stem cell models that have been reported,as well as discuss the issues that impair these studies.We also highlight the prospective application of Huntington's disease stem cell models in the development of novel therapeutic strategies and advancement of personalized medicine.

  20. UML as a cell and biochemistry modeling language. (United States)

    Webb, Ken; White, Tony


    The systems biology community is building increasingly complex models and simulations of cells and other biological entities, and are beginning to look at alternatives to traditional representations such as those provided by ordinary differential equations (ODE). The lessons learned over the years by the software development community in designing and building increasingly complex telecommunication and other commercial real-time reactive systems, can be advantageously applied to the problems of modeling in the biology domain. Making use of the object-oriented (OO) paradigm, the unified modeling language (UML) and Real-Time Object-Oriented Modeling (ROOM) visual formalisms, and the Rational Rose RealTime (RRT) visual modeling tool, we describe a multi-step process we have used to construct top-down models of cells and cell aggregates. The simple example model described in this paper includes membranes with lipid bilayers, multiple compartments including a variable number of mitochondria, substrate molecules, enzymes with reaction rules, and metabolic pathways. We demonstrate the relevance of abstraction, reuse, objects, classes, component and inheritance hierarchies, multiplicity, visual modeling, and other current software development best practices. We show how it is possible to start with a direct diagrammatic representation of a biological structure such as a cell, using terminology familiar to biologists, and by following a process of gradually adding more and more detail, arrive at a system with structure and behavior of arbitrary complexity that can run and be observed on a computer. We discuss our CellAK (Cell Assembly Kit) approach in terms of features found in SBML, CellML, E-CELL, Gepasi, Jarnac, StochSim, Virtual Cell, and membrane computing systems.

  1. A mathematical model of cancer cells with phenotypic plasticity

    Directory of Open Access Journals (Sweden)

    Da Zhou


    Full Text Available Purpose: The phenotypic plasticity of cancer cells is recently becoming a cutting-edge research area in cancer, which challenges the cellular hierarchy proposed by the conventional cancer stem cell theory. In this study, we establish a mathematical model for describing the phenotypic plasticity of cancer cells, based on which we try to find some salient features that can characterize the dynamic behavior of the phenotypic plasticity especially in comparison to the hierarchical model of cancer cells. Methods: We model cancer as population dynamics composed of different phenotypes of cancer cells. In this model, not only can cancer cells divide (symmetrically and asymmetrically and die, but they can also convert into other cellular phenotypes. According to the Law of Mass Action, the cellular processes can be captured by a system of ordinary differential equations (ODEs. On one hand, we can analyze the long-term stability of the model by applying qualitative method of ODEs. On the other hand, we are also concerned about the short-term behavior of the model by studying its transient dynamics. Meanwhile, we validate our model to the cell-state dynamics in published experimental data.Results: Our results show that the phenotypic plasticity plays important roles in both stabilizing the distribution of different phenotypic mixture and maintaining the cancer stem cells proportion. In particular, the phenotypic plasticity model shows decided advantages over the hierarchical model in predicting the phenotypic equilibrium and cancer stem cells’ overshoot reported in previous biological experiments in cancer cell lines.Conclusion: Since the validity of the phenotypic plasticity paradigm and the conventional cancer stem cell theory is still debated in experimental biology, it is worthy of theoretically searching for good indicators to distinguish the two models through quantitative methods. According to our study, the phenotypic equilibrium and overshoot

  2. Mathematical models of cell self-organization

    Directory of Open Access Journals (Sweden)

    Benoît Perthame


    More recently nonlinear hyperbolic and kinetic models also have been used to describe the phenomena at a smaller scale. We explain here some motivations for ‘microscopic’ descriptions, the mathematical difficulties arising in their analysis and how kinetic models can help in understanding the unity of these descriptions.

  3. Sheep primary cells as in vitro models to investigate Mycoplasma agalactiae host cell interactions. (United States)

    Hegde, Shrilakshmi; Gabriel, Cordula; Kragl, Martin; Chopra-Dewasthaly, Rohini


    Appropriate infection models are imperative for the understanding of pathogens like mycoplasmas that are known for their strict host and tissue specificity, and lack of suitable cell and small animal models has hindered pathogenicity studies. This is particularly true for the economically important group of ruminant mycoplasmas whose virulence factors need to be elucidated for designing effective intervention strategies. Mycoplasma agalactiae serves as a useful role model especially because it is phylogenetically very close to M. bovis and causes similar symptoms by as yet unknown mechanisms. Here, we successfully prepared and characterized four different primary sheep cell lines, namely the epithelial and stromal cells from the mammary gland and uterus, respectively. Using immunohistochemistry, we identified vimentin and cytokeratin as specific markers to confirm the typical cell phenotypes of these primary cells. Furthermore, M. agalactiae's consistent adhesion and invasion into these primary cells proves the reliability of these cell models. Mimicking natural infections, mammary epithelial and stromal cells showed higher invasion and adhesion rates compared to the uterine cells as also seen via double immunofluorescence staining. Altogether, we have generated promising in vitro cell models to study host-pathogen interactions of M. agalactiae and related ruminant pathogens in a more authentic manner.

  4. Modeling the impact of granular embedding media, and pulling versus pushing cells on growing cell clones (United States)

    Drasdo, Dirk; Hoehme, Stefan


    In this paper, we explore how potential biomechanical influences on cell cycle entrance and cell migration affect the growth dynamics of cell populations. We consider cell populations growing in free, granular and tissue-like environments using a mathematical single-cell-based model. In a free environment we study the effect of pushing movements triggered by proliferation versus active pulling movements of cells stretching cell-cell contacts on the multi-cellular kinetics and the cell population morphotype. By growing cell clones embedded in agarose gel or cells of another type, one can mimic aspects of embedding tissues. We perform simulation studies of cell clones expanding in an environment of granular objects and of chemically inert cells. In certain parameter ranges, we find the formation of invasive fingers reminiscent of viscous fingering. Since the simulation studies are highly computation-time consuming, we mainly study one-cell-thick monolayers and show that for selected parameter settings the results also hold for multi-cellular spheroids. Finally, we compare our model to the experimentally observed growth dynamics of multi-cellular spheroids in agarose gel.

  5. Similarity on neural stem cells and brain tumor stem cells in transgenic brain tumor mouse models

    Institute of Scientific and Technical Information of China (English)

    Guanqun Qiao; Qingquan Li; Gang Peng; Jun Ma; Hongwei Fan; Yingbin Li


    Although it is believed that glioma is derived from brain tumor stem cells, the source and molecular signal pathways of these cells are stil unclear. In this study, we used stable doxycycline-inducible transgenic mouse brain tumor models (c-myc+/SV40Tag+/Tet-on+) to explore the malignant trans-formation potential of neural stem cells by observing the differences of neural stem cel s and brain tumor stem cells in the tumor models. Results showed that chromosome instability occurred in brain tumor stem cells. The numbers of cytolysosomes and autophagosomes in brain tumor stem cells and induced neural stem cel s were lower and the proliferative activity was obviously stronger than that in normal neural stem cells. Normal neural stem cells could differentiate into glial fibril ary acidic protein-positive and microtubule associated protein-2-positive cells, which were also negative for nestin. However, glial fibril ary acidic protein/nestin, microtubule associated protein-2/nestin, and glial fibril ary acidic protein/microtubule associated protein-2 double-positive cells were found in induced neural stem cells and brain tumor stem cel s. Results indicate that induced neural stem cells are similar to brain tumor stem cells, and are possibly the source of brain tumor stem cells.

  6. Mechanical Response of Single Plant Cells to Cell Poking: A Numerical Simulation Model

    Institute of Scientific and Technical Information of China (English)

    Rong Wang; Qun-Ying Jiao; De-Qiang Wei


    Cell poking is an experimental technique that is widely used to study the mechanical properties of plant cells. A full understanding of the mechanical responses of plant cells to poking force is helpful for experimental work. The aim of this study was to numerically investigate the stress distribution of the cell wall,cell turgor, and deformation of plant cells in response to applied poking force. Furthermore, the locations damaged during poking were analyzed. The model simulates cell poking, with the cell treated as a spherical,homogeneous, isotropic elastic membrane, filled with incompressible, highly viscous liquid. Equilibrium equations for the contact region and the non-contact regions were determined by using membrane theory.The boundary conditions and continuity conditions for the solution of the problem were found. The forcedeformation curve, turgor pressure and tension of the cell wall under cell poking conditions were obtained.The tension of the cell wall circumference was larger than that of the meridian. In general, maximal stress occurred at the equator around. When cell deformation increased to a certain level, the tension at the poker tip exceeded that of the equator. Breakage of the cell wall may start from the equator or the poker tip,depending on the deformation. A nonlinear model is suitable for estimating turgor, stress, and stiffness,and numerical simulation is a powerful method for determining plant cell mechanical properties.

  7. Improved Computational Model of Grid Cells Based on Column Structure

    Institute of Scientific and Technical Information of China (English)

    Yang Zhou; Dewei Wu; Weilong Li; Jia Du


    To simulate the firing pattern of biological grid cells, this paper presents an improved computational model of grid cells based on column structure. In this model, the displacement along different directions is processed by modulus operation, and the obtained remainder is associated with firing rate of grid cell. Compared with the original model, the improved parts include that: the base of modulus operation is changed, and the firing rate in firing field is encoded by Gaussian⁃like function. Simulation validates that the firing pattern generated by the improved computational model is more consistent with biological characteristic than original model. Besides, the firing pattern is badly influenced by the cumulative positioning error, but the computational model can also generate the regularly hexagonal firing pattern when the real⁃time positioning results are modified.

  8. Modeling of Flow in Nuclear Reactor Fuel Cell Outlet

    Directory of Open Access Journals (Sweden)

    František URBAN


    Full Text Available Safe and effective load of nuclear reactor fuel cells demands qualitative and quantitative analysis of relations between coolant temperature in fuel cell outlet temperature measured by thermocouple and middle temperature of coolant in thermocouple plane position. In laboratory at Insitute of thermal power engineering of the Slovak University of Technology in Bratislava was installed an experimental physical fuel cell model of VVER 440 nuclear power plant with V 213 nuclear reactors. Objective of measurements on physical model was temperature and velocity profiles analysis in the fuel cell outlet. In this paper the measured temperature and velocity profiles are compared with the results of CFD simulation of fuel cell physical model coolant flow.

  9. An In Vitro Nematic Model for Proliferating Cell Cultures

    CERN Document Server

    Pai, Sunil; Green, Morgaine; Cordeiro, Christine; Cabral, Elise; Chen, Bertha; Baer, Thomas


    Confluent populations of elongated cells give rise to ordered patterns seen in nematic phase liquid crystals. We correlate cell elongation and intercellular distance with intercellular alignment using an amorphous spin glass model. We compare in vitro time-lapse imaging with Monte Carlo simulation results by framing a novel hard ellipses model in terms of Boltzmann statistics. Furthermore, we find a statistically distinct alignment energy at quasi-steady state among fibroblasts, smooth muscle cells, and pluripotent cell populations when cultured in vitro. These findings have important implications in both non-invasive clinical screening of the stem cell differentiation process and in relating shape parameters to coupling in active crystal systems such as nematic cell monolayers.

  10. Modelling Neurodegenerative Diseases Using Human Pluripotent Stem Cells

    DEFF Research Database (Denmark)

    Hall, Vanessa Jane


    , frontotemporal dementia and Parkinson’s disease using pluripotent stem cells is described, along with the advent of gene-editing, which has been the complimentary tool for the field. Current methods used to model these diseases are predominantly dependent on 2D cell culture methods. Outcomes reveal that only...... that includes studying more complex 3D cell cultures, as well as accelerating aging of the neurons, may help to yield stronger phenotypes in the cultured cells. Thus, the use and application of pluripotent stem cells for modelling disease have already shown to be a powerful approach for discovering more about...... these diseases, but will lead to even more findings in the future as gene and cell culture technology continues to develop....

  11. Synthetic biology of minimal living cells: primitive cell models and semi-synthetic cells. (United States)

    Stano, Pasquale


    This article summarizes a contribution presented at the ESF 2009 Synthetic Biology focused on the concept of the minimal requirement for life and on the issue of constructive (synthetic) approaches in biological research. The attempts to define minimal life within the framework of autopoietic theory are firstly described, and a short report on the development of autopoietic chemical systems based on fatty acid vesicles, which are relevant as primitive cell models is given. These studies can be used as a starting point for the construction of more complex systems, firstly being inspired by possible origins of life scenarioes (and therefore by considering primitive functions), then by considering an approach based on modern biomacromolecular-encoded functions. At this aim, semi-synthetic minimal cells are defined as those man-made vesicle-based systems that are composed of the minimal number of genes, proteins, biomolecules and which can be defined as living. Recent achievements on minimal sized semi-synthetic cells are then discussed, and the kind of information obtained is recognized as being distinctively derived by a constructive approach. Synthetic biology is therefore a fundamental tool for gaining basic knowledge about biosystems, and it should not be confined at all to the engineering side.

  12. Mechanical behavior of cells within a cell-based model of wheat leaf growth

    Directory of Open Access Journals (Sweden)

    Ulyana Zubairova


    Full Text Available Understanding the principles and mechanisms of cell growth coordination in plant tissue remains an outstanding challenge for modern developmental biology. Cell-based modeling is a widely used technique for studying the geometric and topological features of plant tissue morphology during growth. We developed a quasi-one-dimensional model of unidirectional growth of a tissue layer in a linear leaf blade that takes cell autonomous growth mode into account. The model allows for fitting of the visible cell length using the experimental cell length distribution along the longitudinal axis of a wheat leaf epidermis. Additionally, it describes changes in turgor and osmotic pressures for each cell in the growing tissue. Our numerical experiments show that the pressures in the cell change over the cell cycle, and in symplastically growing tissue, they vary from cell to cell and strongly depend on the leaf growing zone to which the cells belong. Therefore, we believe that the mechanical signals generated by pressures are important to consider in simulations of tissue growth as possible targets for molecular genetic regulators of individual cell growth.

  13. Hybrid multiscale modeling and prediction of cancer cell behavior. (United States)

    Zangooei, Mohammad Hossein; Habibi, Jafar


    Understanding cancer development crossing several spatial-temporal scales is of great practical significance to better understand and treat cancers. It is difficult to tackle this challenge with pure biological means. Moreover, hybrid modeling techniques have been proposed that combine the advantages of the continuum and the discrete methods to model multiscale problems. In light of these problems, we have proposed a new hybrid vascular model to facilitate the multiscale modeling and simulation of cancer development with respect to the agent-based, cellular automata and machine learning methods. The purpose of this simulation is to create a dataset that can be used for prediction of cell phenotypes. By using a proposed Q-learning based on SVR-NSGA-II method, the cells have the capability to predict their phenotypes autonomously that is, to act on its own without external direction in response to situations it encounters. Computational simulations of the model were performed in order to analyze its performance. The most striking feature of our results is that each cell can select its phenotype at each time step according to its condition. We provide evidence that the prediction of cell phenotypes is reliable. Our proposed model, which we term a hybrid multiscale modeling of cancer cell behavior, has the potential to combine the best features of both continuum and discrete models. The in silico results indicate that the 3D model can represent key features of cancer growth, angiogenesis, and its related micro-environment and show that the findings are in good agreement with biological tumor behavior. To the best of our knowledge, this paper is the first hybrid vascular multiscale modeling of cancer cell behavior that has the capability to predict cell phenotypes individually by a self-generated dataset.


    In this study, we established a computational model describing the molecular circuit underlying B cell terminal differentiation and how TCDD may affect this process by impinging upon various molecular targets.

  15. Design, Modeling, and Development of Microbial Cell Factories

    KAUST Repository

    Kodzius, Rimantas


    Using Metagenomic analysis, computational modeling, single cell and genome editing technologies, we will express desired microbial genes and their networks in suitable hosts for mass production of energy, food, and fine chemicals.

  16. Dynamic Model of High Temperature PEM Fuel Cell Stack Temperature

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen


    cathode air cooled 30 cell HTPEM fuel cell stack developed at the Institute of Energy Technology at Aalborg University. This fuel cell stack uses PEMEAS Celtec P-1000 membranes, runs on pure hydrogen in a dead end anode configuration with a purge valve. The cooling of the stack is managed by running...... conduction through stack insulation, cathode air convection and heating of the inlet gasses in manifold. Various measurements are presented to validate the model predictions of the stack temperatures....

  17. Advanced impedance modeling of solid oxide electrochemical cells

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Hjelm, Johan


    Impedance spectroscopy is a powerful technique for detailed study of the electrochemical and transport processes that take place in fuel cells and electrolysis cells, including solid oxide cells (SOCs). Meaningful analysis of impedance measurements is nontrivial, however, because a large number o...... analysis methods and integrates the analysis process in a modular workflow – data validation (Kramers-Kronig), clean-up, visualization (DRT and others), modeling (nonlinear least-squares fitting), and final plotting for publication....

  18. Acoel and platyhelminth models for stem-cell research (United States)


    Acoel and platyhelminth worms are particularly attractive invertebrate models for stem-cell research because their bodies are continually renewed from large pools of somatic stem cells. Several recent studies, including one in BMC Developmental Biology, are beginning to reveal the cellular dynamics and molecular basis of stem-cell function in these animals. See research article PMID:20236484

  19. Mathematical Modeling of the Induced Mutation Process in Bacterial Cells (United States)

    Belov, Oleg V.; Krasavin, Evgeny A.; Parkhomenko, Alexander Yu.


    A mathematical model of the ultraviolet (UV) irradiation-induced mutation process in bacterial cells Escherichia coli is developed. Using mathematical approaches, the whole chain of events is tracked from a cell exposure to the damaging factor to mutation formation in the DNA chain. An account of the key special features of the regulation of this genetic network allows predicting the effects induced by the cell exposure to certain UV energy fluence.

  20. A Human Corneal Epithelial Cell Line Model for Limbal Stem Cell Biology and Limbal Immunobiology. (United States)

    Shaharuddin, Bakiah; Ahmad, Sajjad; Md Latar, Nani; Ali, Simi; Meeson, Annette


    : Limbal stem cell (LSC) deficiency is a visually debilitating condition caused by abnormal maintenance of LSCs. It is treated by transplantation of donor-derived limbal epithelial cells (LECs), the success of which depends on the presence and quality of LSCs within the transplant. Understanding the immunobiological responses of these cells within the transplants could improve cell engraftment and survival. However, human corneal rings used as a source of LSCs are not always readily available for research purposes. As an alternative, we hypothesized that a human telomerase-immortalized corneal epithelial cell (HTCEC) line could be used as a model for studying LSC immunobiology. HTCEC constitutively expressed human leukocyte antigen (HLA) class I but not class II molecules. However, when stimulated by interferon-γ, HTCECs then expressed HLA class II antigens. Some HTCECs were also migratory in response to CXCL12 and expressed stem cell markers, Nanog, Oct4, and Sox2. In addition because both HTCECs and LECs contain side population (SP) cells, which are an enriched LSC population, we used these SP cells to show that some HTCEC SP cells coexpressed ABCG2 and ABCB5. HTCEC SP and non-side population (NSP) cells also expressed CXCR4, but the SP cells expressed higher levels. Both were capable of colony formation, but the NSP colonies were smaller and contained fewer cells. In addition, HTCECs expressed ΔNp63α. These results suggest the HTCEC line is a useful model for further understanding LSC biology by using an in vitro approach without reliance on a supply of human tissue. Limbal stem cell deficiency is a painful eye condition caused by abnormal maintenance of limbal stem cells. It is treated by transplantation of limbal epithelial cells derived from human tissue. The success of this treatment depends of the quality of the cells transplanted; however, some transplants fail. Understanding more about the immunobiology of these cells within the transplants could


    This report presents a model developed to study growth and differentiation of primary cultures of ureteric epithelial cells from embryonic C57BL/6N mouse urinary tracts. Single cells were resuspended in medium and plated onto transwells coated with collagen IV and laminin. Basa...

  2. Modeling universal dynamics of cell spreading on elastic substrates. (United States)

    Fan, Houfu; Li, Shaofan


    A three-dimensional (3D) multiscale moving contact line model is combined with a soft matter cell model to study the universal dynamics of cell spreading over elastic substrates. We have studied both the early stage and the late stage cell spreading by taking into account the actin tension effect. In this work, the cell is modeled as an active nematic droplet, and the substrate is modeled as a St. Venant Kirchhoff elastic medium. A complete 3D simulation of cell spreading has been carried out. The simulation results show that the spreading area versus spreading time at different stages obeys specific power laws, which is in good agreement with experimental data and theoretical prediction reported in the literature. Moreover, the simulation results show that the substrate elasticity may affect force dipole distribution inside the cell. The advantage of this approach is that it combines the hydrodynamics of actin retrograde flow with moving contact line model so that it can naturally include actin tension effect resulting from actin polymerization and actomyosin contraction, and thus it might be capable of simulating complex cellular scale phenomenon, such as cell spreading or even crawling.

  3. Multi-scale models of cell and tissue dynamics. (United States)

    Stolarska, Magdalena A; Kim, Yangjin; Othmer, Hans G


    Cell and tissue movement are essential processes at various stages in the life cycle of most organisms. The early development of multi-cellular organisms involves individual and collective cell movement; leukocytes must migrate towards sites of infection as part of the immune response; and in cancer, directed movement is involved in invasion and metastasis. The forces needed to drive movement arise from actin polymerization, molecular motors and other processes, but understanding the cell- or tissue-level organization of these processes that is needed to produce the forces necessary for directed movement at the appropriate point in the cell or tissue is a major challenge. In this paper, we present three models that deal with the mechanics of cells and tissues: a model of an arbitrarily deformable single cell, a discrete model of the onset of tumour growth in which each cell is treated individually, and a hybrid continuum-discrete model of the later stages of tumour growth. While the models are different in scope, their underlying mechanical and mathematical principles are similar and can be applied to a variety of biological systems.

  4. A device model for the tandem junction solar cell (United States)

    Matzen, W. T.; Chiang, S. Y.; Carbajal, B. G.


    A conceptual device model has been developed to explain operation of the tandem junction cell (TJC) when back contacts only are used. Operation and parameters of the cell are explained by transistor action. Experimental observations are presented which confirm that current is collected for carrier generation in the front uncontacted n(plus) region. The model should be useful as a guideline to optimize the TJC by application of transistor design principles.

  5. Transient air cooling thermal modeling of a PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Adzakpa, K.P.; Ramousse, J.; Dube, Y.; Akremi, H.; Agbossou, K. [Hydrogen Research Institute and Departement de genie electrique, Universite du Quebec a Trois-Rivieres, CP 500, Trois-Rivieres (QC) (Canada); Dostie, M.; Poulin, A.; Fournier, M. [LTE-Hydro-Quebec, 600 av. de la Montagne, Shawinigan (QC) (Canada)


    Fuel cell utilization for automobile and residential applications is a promising option in order to help reduce environmental concerns such as pollution. However, fuel cell development requires addressing their dynamic behavior to improve their performances and their life cycle. Since the temperature distribution in the cell is known to be an important factor to the fuel cell's efficiency, a cooling device is often added to homogenize the temperature in the cell and to ensure temperature control. A 3D dynamic thermal model of a single fuel cell is presented in this work in order to study the temperature distribution in a fuel cell cooled from the bottom to the top with air. The model is governed by the thermal energy balance, taking into account the inlet gas humidity. The model is developed with the finite difference method and is implemented in the Matlab/Simulink environment. The validation is based on the performances of the ''NEXA'' fuel cell produced by Ballard Power Systems. The efficiency analysis of that air cooling device reveals that the cell temperature is directly linked to the current density and to the gas humidity - varying from 30 C at 5A to 80 C at 35A at low humidity. Moreover, the temperature non-uniformity in the stack is shown to be very high. As a result, temperatures are higher at the top part of the cell than at the bottom part, with a difference of up to a 5 C. Moreover the non-uniformity of the air cooling between the cells of the stack leads to large temperature variations, up to 8 C, from one cell to another. These temperature variations result in large voltage disparities between the cells, which reduce the total electrical power of the entire stack. (author)

  6. Microfluidic cardiac cell culture model (μCCCM). (United States)

    Giridharan, Guruprasad A; Nguyen, Mai-Dung; Estrada, Rosendo; Parichehreh, Vahidreza; Hamid, Tariq; Ismahil, Mohamed Ameen; Prabhu, Sumanth D; Sethu, Palaniappan


    Physiological heart development and cardiac function rely on the response of cardiac cells to mechanical stress during hemodynamic loading and unloading. These stresses, especially if sustained, can induce changes in cell structure, contractile function, and gene expression. Current cell culture techniques commonly fail to adequately replicate physical loading observed in the native heart. Therefore, there is a need for physiologically relevant in vitro models that recreate mechanical loading conditions seen in both normal and pathological conditions. To fulfill this need, we have developed a microfluidic cardiac cell culture model (μCCCM) that for the first time allows in vitro hemodynamic stimulation of cardiomyocytes by directly coupling cell structure and function with fluid induced loading. Cells are cultured in a small (1 cm diameter) cell culture chamber on a thin flexible silicone membrane. Integrating the cell culture chamber with a pump, collapsible pulsatile valve and an adjustable resistance element (hemostatic valve) in series allow replication of various loading conditions experienced in the heart. This paper details the design, modeling, fabrication and characterization of fluid flow, pressure and stretch generated at various frequencies to mimic hemodynamic conditions associated with the normal and failing heart. Proof-of-concept studies demonstrate successful culture of an embryonic cardiomyoblast line (H9c2 cells) and establishment of an in vivo like phenotype within this system.

  7. Computation Molecular Kinetics Model of HZE Induced Cell Cycle Arrest (United States)

    Cucinotta, Francis A.; Ren, Lei


    Cell culture models play an important role in understanding the biological effectiveness of space radiation. High energy and charge (HZE) ions produce prolonged cell cycle arrests at the G1/S and G2/M transition points in the cell cycle. A detailed description of these phenomena is needed to integrate knowledge of the expression of DNA damage in surviving cells, including the determination of relative effectiveness factors between different types of radiation that produce differential types of DNA damage and arrest durations. We have developed a hierarchical kinetics model that tracks the distribution of cells in various cell phase compartments (early G1, late G1, S, G2, and M), however with transition rates that are controlled by rate-limiting steps in the kinetics of cyclin-cdk's interactions with their families of transcription factors and inhibitor molecules. The coupling of damaged DNA molecules to the downstream cyclin-cdk inhibitors is achieved through a description of the DNA-PK and ATM signaling pathways. For HZE irradiations we describe preliminary results, which introduce simulation of the stochastic nature of the number of direct particle traversals per cell in the modulation of cyclin-cdk and cell cycle population kinetics. Comparison of the model to data for fibroblast cells irradiated photons or HZE ions are described.

  8. Non-Markovian Model for Transport and Reactions of Particles in Spiny Dendrites (United States)

    Fedotov, Sergei; Méndez, Vicenç


    Motivated by the experiments [Santamaria , Neuron 52, 635 (2006)NERNET0896-627310.1016/j.neuron.2006.10.025] that indicated the possibility of subdiffusive transport of molecules along dendrites of cerebellar Purkinje cells, we develop a mesoscopic model for transport and chemical reactions of particles in spiny dendrites. The communication between spines and a parent dendrite is described by a non-Markovian random process and, as a result, the overall movement of particles can be subdiffusive. A system of integrodifferential equations is derived for the particles densities in dendrites and spines. This system involves the spine-dendrite interaction term which describes the memory effects and nonlocality in space. We consider the impact of power-law waiting time distributions on the transport of biochemical signals and mechanism of the accumulation of plasticity-inducing signals inside spines.

  9. Mathematical and Computational Modeling of Polymer Exchange Membrane Fuel Cells (United States)

    Ulusoy, Sehribani

    In this thesis a comprehensive review of fuel cell modeling has been given and based on the review, a general mathematical fuel cell model has been developed in order to understand the physical phenomena governing the fuel cell behavior and in order to contribute to the efforts investigating the optimum performance at different operating conditions as well as with different physical parameters. The steady state, isothermal model presented here accounts for the combined effects of mass and species transfer, momentum conservation, electrical current distribution through the gas channels, the electrodes and the membrane, and the electrochemical kinetics of the reactions in the anode and cathode catalyst layers. One of the important features of the model is that it proposes a simpler modified pseudo-homogeneous/agglomerate catalyst layer model which takes the advantage of the simplicity of pseudo-homogenous modeling while taking into account the effects of the agglomerates in the catalyst layer by using experimental geometric parameters published. The computation of the general mathematical model can be accomplished in 3D, 2D and 1D with the proper assumptions. Mainly, there are two computational domains considered in this thesis. The first modeling domain is a 2D Membrane Electrode Assembly (MEA) model including the modified agglomerate/pseudo-homogeneous catalyst layer modeling with consistent treatment of water transport in the MEA while the second domain presents a 3D model with different flow filed designs: straight, stepped and tapered. COMSOL Multiphysics along with Batteries and Fuel Cell Module have been used for 2D & 3D model computations while ANSYS FLUENT PEMFC Module has been used for only 3D two-phase computation. Both models have been validated with experimental data. With 2D MEA model, the effects of temperature and water content of the membrane as well as the equivalent weight of the membrane on the performance have been addressed. 3D COMSOL simulation

  10. Simulation of Cell Adhesion using a Particle Transport Model (United States)

    Chesnutt, Jennifer


    An efficient computational method for simulation of cell adhesion through protein binding forces is discussed. In this method, the cells are represented by deformable elastic particles, and the protein binding is represented by a rate equation. The method is first developed for collision and adhesion of two similar cells impacting on each other from opposite directions. The computational method is then applied in a particle-transport model for a cloud of interacting and colliding cells, each of which are represented by particles of finite size. One application might include red blood cells adhering together to form rouleaux, which are chains of red blood cells that are found in different parts of the circulatory system. Other potential applications include adhesion of platelets to a blood vessel wall or mechanical heart valve, which is a precursor of thrombosis formation, or adhesion of cancer cells to organ walls in the lymphatic, circulatory, digestive or pulmonary systems.

  11. A Three-Dimensional Cell Culture Model To Study Enterovirus Infection of Polarized Intestinal Epithelial Cells. (United States)

    Drummond, Coyne G; Nickerson, Cheryl A; Coyne, Carolyn B


    Despite serving as the primary entry portal for coxsackievirus B (CVB), little is known about CVB infection of the intestinal epithelium, owing at least in part to the lack of suitable in vivo models and the inability of cultured cells to recapitulate the complexity and structure associated with the gastrointestinal (GI) tract. Here, we report on the development of a three-dimensional (3-D) organotypic cell culture model of Caco-2 cells to model CVB infection of the gastrointestinal epithelium. We show that Caco-2 cells grown in 3-D using the rotating wall vessel (RWV) bioreactor recapitulate many of the properties of the intestinal epithelium, including the formation of well-developed tight junctions, apical-basolateral polarity, brush borders, and multicellular complexity. In addition, transcriptome analyses using transcriptome sequencing (RNA-Seq) revealed the induction of a number of genes associated with intestinal epithelial differentiation and/or intestinal processes in vivo when Caco-2 cells were cultured in 3-D. Applying this model to CVB infection, we found that although the levels of intracellular virus production were similar in two-dimensional (2-D) and 3-D Caco-2 cell cultures, the release of infectious CVB was enhanced in 3-D cultures at early stages of infection. Unlike CVB, the replication of poliovirus (PV) was significantly reduced in 3-D Caco-2 cell cultures. Collectively, our studies show that Caco-2 cells grown in 3-D using the RWV bioreactor provide a cell culture model that structurally and transcriptionally represents key aspects of cells in the human GI tract and can thus be used to expand our understanding of enterovirus-host interactions in intestinal epithelial cells. IMPORTANCE Coxsackievirus B (CVB), a member of the enterovirus family of RNA viruses, is associated with meningitis, pericarditis, diabetes, dilated cardiomyopathy, and myocarditis, among other pathologies. CVB is transmitted via the fecal-oral route and encounters the

  12. How can cells sense the elasticity of a substrate? An analysis using a cell tensegrity model

    Directory of Open Access Journals (Sweden)

    G De Santis


    Full Text Available A eukaryotic cell attaches and spreads on substrates, whether it is the extracellular matrix naturally produced by the cell itself, or artificial materials, such as tissue-engineered scaffolds. Attachment and spreading require the cell to apply forces in the nN range to the substrate via adhesion sites, and these forces are balanced by the elastic response of the substrate. This mechanical interaction is one determinant of cell morphology and, ultimately, cell phenotype. In this paper we use a finite element model of a cell, with a tensegrity structure to model the cytoskeleton of actin filaments and microtubules, to explore the way cells sense the stiffness of the substrate and thereby adapt to it. To support the computational results, an analytical 1D model is developed for comparison. We find that (i the tensegrity hypothesis of the cytoskeleton is sufficient to explain the matrix-elasticity sensing, (ii cell sensitivity is not constant but has a bell-shaped distribution over the physiological matrix-elasticity range, and (iii the position of the sensitivity peak over the matrix-elasticity range depends on the cytoskeletal structure and in particular on the F-actin organisation. Our model suggests that F-actin reorganisation observed in mesenchymal stem cells (MSCs in response to change of matrix elasticity is a structural-remodelling process that shifts the sensitivity peak towards the new value of matrix elasticity. This finding discloses a potential regulatory role of scaffold stiffness for cell differentiation.

  13. Models to Study NK Cell Biology and Possible Clinical Application. (United States)

    Zamora, Anthony E; Grossenbacher, Steven K; Aguilar, Ethan G; Murphy, William J


    Natural killer (NK) cells are large granular lymphocytes of the innate immune system, responsible for direct targeting and killing of both virally infected and transformed cells. NK cells rapidly recognize and respond to abnormal cells in the absence of prior sensitization due to their wide array of germline-encoded inhibitory and activating receptors, which differs from the receptor diversity found in B and T lymphocytes that is due to the use of recombination-activation gene (RAG) enzymes. Although NK cells have traditionally been described as natural killers that provide a first line of defense prior to the induction of adaptive immunity, a more complex view of NK cells is beginning to emerge, indicating they may also function in various immunoregulatory roles and have the capacity to shape adaptive immune responses. With the growing appreciation for the diverse functions of NK cells, and recent technological advancements that allow for a more in-depth understanding of NK cell biology, we can now begin to explore new ways to manipulate NK cells to increase their clinical utility. In this overview unit, we introduce the reader to various aspects of NK cell biology by reviewing topics ranging from NK cell diversity and function, mouse models, and the roles of NK cells in health and disease, to potential clinical applications. © 2015 by John Wiley & Sons, Inc. Copyright © 2015 John Wiley & Sons, Inc.

  14. Construction of cell type-specific logic models of signaling networks using CellNOpt. (United States)

    Morris, Melody K; Melas, Ioannis; Saez-Rodriguez, Julio


    Mathematical models are useful tools for understanding protein signaling networks because they provide an integrated view of pharmacological and toxicological processes at the molecular level. Here we describe an approach previously introduced based on logic modeling to generate cell-specific, mechanistic and predictive models of signal transduction. Models are derived from a network encoding prior knowledge that is trained to signaling data, and can be either binary (based on Boolean logic) or quantitative (using a recently developed formalism, constrained fuzzy logic). The approach is implemented in the freely available tool CellNetOptimizer (CellNOpt). We explain the process CellNOpt uses to train a prior knowledge network to data and illustrate its application with a toy example as well as a realistic case describing signaling networks in the HepG2 liver cancer cell line.

  15. Approaches to myosin modelling in a two-phase flow model for cell motility (United States)

    Kimpton, L. S.; Whiteley, J. P.; Waters, S. L.; Oliver, J. M.


    A wide range of biological processes rely on the ability of cells to move through their environment. Mathematical models have been developed to improve our understanding of how cells achieve motion. Here we develop models that explicitly track the cell's distribution of myosin within a two-phase flow framework. Myosin is a small motor protein which is important for contracting the cell's actin cytoskeleton and enabling cell motion. The two phases represent the actin network and the cytosol in the cell. We start from a fairly general description of myosin kinetics, advection and diffusion in the two-phase flow framework, then identify a number of sub-limits of the model that may be relevant in practice, two of which we investigate further via linear stability analyses and numerical simulations. We demonstrate that myosin-driven contraction of the actin network destabilizes a stationary steady state leading to cell motion, but that rapid diffusion of myosin and rapid unbinding of myosin from the actin network are stabilizing. We use numerical simulation to investigate travelling-wave solutions relevant to a steadily gliding cell and we consider a reduction of the model in which the cell adheres strongly to the substrate on which it is crawling. This work demonstrates that a number of existing models for the effect of myosin on cell motility can be understood as different sub-limits of our two-phase flow model.

  16. A quantitative and dynamic model for plant stem cell regulation.

    Directory of Open Access Journals (Sweden)

    Florian Geier

    Full Text Available Plants maintain pools of totipotent stem cells throughout their entire life. These stem cells are embedded within specialized tissues called meristems, which form the growing points of the organism. The shoot apical meristem of the reference plant Arabidopsis thaliana is subdivided into several distinct domains, which execute diverse biological functions, such as tissue organization, cell-proliferation and differentiation. The number of cells required for growth and organ formation changes over the course of a plants life, while the structure of the meristem remains remarkably constant. Thus, regulatory systems must be in place, which allow for an adaptation of cell proliferation within the shoot apical meristem, while maintaining the organization at the tissue level. To advance our understanding of this dynamic tissue behavior, we measured domain sizes as well as cell division rates of the shoot apical meristem under various environmental conditions, which cause adaptations in meristem size. Based on our results we developed a mathematical model to explain the observed changes by a cell pool size dependent regulation of cell proliferation and differentiation, which is able to correctly predict CLV3 and WUS over-expression phenotypes. While the model shows stem cell homeostasis under constant growth conditions, it predicts a variation in stem cell number under changing conditions. Consistent with our experimental data this behavior is correlated with variations in cell proliferation. Therefore, we investigate different signaling mechanisms, which could stabilize stem cell number despite variations in cell proliferation. Our results shed light onto the dynamic constraints of stem cell pool maintenance in the shoot apical meristem of Arabidopsis in different environmental conditions and developmental states.

  17. Mechanistic modeling confronts the complexity of molecular cell biology. (United States)

    Phair, Robert D


    Mechanistic modeling has the potential to transform how cell biologists contend with the inescapable complexity of modern biology. I am a physiologist-electrical engineer-systems biologist who has been working at the level of cell biology for the past 24 years. This perspective aims 1) to convey why we build models, 2) to enumerate the major approaches to modeling and their philosophical differences, 3) to address some recurrent concerns raised by experimentalists, and then 4) to imagine a future in which teams of experimentalists and modelers build-and subject to exhaustive experimental tests-models covering the entire spectrum from molecular cell biology to human pathophysiology. There is, in my view, no technical obstacle to this future, but it will require some plasticity in the biological research mind-set.

  18. On a Pioneering Polymer Electrolyte Fuel Cell Model

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Adam Z.; Meyers, Jeremy P.


    "Polymer Electrolyte Fuel Cell Model" is a seminal work that continues to form the basis for modern modeling efforts, especially models concerning the membrane and its behavior at the continuum level. The paper is complete with experimental data, modeling equations, model validation, and optimization scenarios. While the treatment of the underlying phenomena is limited to isothermal, single-phase conditions, and one-dimensional flow, it represents the key interactions within the membrane at the center of the PEFC. It focuses on analyzing the water balance within the cell and clearly demonstrates the complex interactions of water diffusion and electro-osmotic flux. Cell-level and system-level water balance are key to the development of efficient PEFCs going forward, particularly as researchers address the need to simplify humidification and recycle configurations while increasing the operating temperature of the stack to minimize radiator requirements.

  19. Landolphia owariensis Attenuates Alcohol-induced Cerebellar Neurodegeneration: Significance of Neurofilament Protein Alteration in the Purkinje Cells

    Directory of Open Access Journals (Sweden)

    Oyinbo Charles A.


    Full Text Available Background: Alcohol-induced cerebellar neurodegeneration is a neuroadaptation that is associated with chronic alcohol abuse. Conventional drugs have been largely unsatisfactory in preventing neurodegeneration. Yet, multimodal neuro-protective therapeutic agents have been hypothesised to have high therapeutic potential for the treatment of CNS conditions; there is yet a dilemma of how this would be achieved. Contrarily, medicinal botanicals are naturally multimodal in their mechanism of action.

  20. Concise Review: Stem Cell Trials Using Companion Animal Disease Models. (United States)

    Hoffman, Andrew M; Dow, Steven W


    Studies to evaluate the therapeutic potential of stem cells in humans would benefit from more realistic animal models. In veterinary medicine, companion animals naturally develop many diseases that resemble human conditions, therefore, representing a novel source of preclinical models. To understand how companion animal disease models are being studied for this purpose, we reviewed the literature between 2008 and 2015 for reports on stem cell therapies in dogs and cats, excluding laboratory animals, induced disease models, cancer, and case reports. Disease models included osteoarthritis, intervertebral disc degeneration, dilated cardiomyopathy, inflammatory bowel diseases, Crohn's fistulas, meningoencephalomyelitis (multiple sclerosis-like), keratoconjunctivitis sicca (Sjogren's syndrome-like), atopic dermatitis, and chronic (end-stage) kidney disease. Stem cells evaluated in these studies included mesenchymal stem-stromal cells (MSC, 17/19 trials), olfactory ensheathing cells (OEC, 1 trial), or neural lineage cells derived from bone marrow MSC (1 trial), and 16/19 studies were performed in dogs. The MSC studies (13/17) used adipose tissue-derived MSC from either allogeneic (8/13) or autologous (5/13) sources. The majority of studies were open label, uncontrolled studies. Endpoints and protocols were feasible, and the stem cell therapies were reportedly safe and elicited beneficial patient responses in all but two of the trials. In conclusion, companion animals with naturally occurring diseases analogous to human conditions can be recruited into clinical trials and provide realistic insight into feasibility, safety, and biologic activity of novel stem cell therapies. However, improvements in the rigor of manufacturing, study design, and regulatory compliance will be needed to better utilize these models. Stem Cells 2016;34:1709-1729. © 2016 AlphaMed Press.

  1. Stochasticity in cell biology: Modeling across levels (United States)

    Pedraza, Juan Manuel


    Effective modeling of biological processes requires focusing on a particular level of description, and this requires summarizing de details of lower levels into effective variables and properly accounting for the constrains that other levels impose. In the context of stochasticity in gene expression, I will show how the details of the stochastic process can be characterized by a few effective parameters, which facilitates modeling but complicates interpretation of current experiments. I will show how the resulting noise can provide advantageous or deleterious phenotypic fluctuation and how noise control in the copy number control system of plasmids can change the selective pressures. This system illustrates the direct connection between molecular dynamics and evolutionary dynamics.

  2. PEM fuel cell modeling and simulation using Matlab

    CERN Document Server

    Spiegel, Colleen


    Although, the basic concept of a fuel cell is quite simple, creating new designs and optimizing their performance takes serious work and a mastery of several technical areas. PEM Fuel Cell Modeling and Simulation Using Matlab, provides design engineers and researchers with a valuable tool for understanding and overcoming barriers to designing and building the next generation of PEM Fuel Cells. With this book, engineers can test components and verify designs in the development phase, saving both time and money.Easy to read and understand, this book provides design and modelling tips for

  3. Multiscale Modeling of Red Blood Cells Squeezing through Submicron Slits (United States)

    Peng, Zhangli; Lu, Huijie


    A multiscale model is applied to study the dynamics of healthy red blood cells (RBCs), RBCs in hereditary spherocytosis, and sickle cell disease squeezing through submicron slits. This study is motivated by the mechanical filtration of RBCs by inter-endothelial slits in the spleen. First, the model is validated by comparing the simulation results with experiments. Secondly, the deformation of the cytoskeleton in healthy RBCs is investigated. Thirdly, the mechanisms of damage in hereditary spherocytosis are investigated. Finally, the effects of cytoplasm and membrane viscosities, especially in sickle cell disease, are examined. The simulations results provided guidance for future experiments to explore the dynamics of RBCs under extreme deformation.

  4. Computer models of bacterial cells: from generalized coarsegrained to genome-specific modular models (United States)

    Nikolaev, Evgeni V.; Atlas, Jordan C.; Shuler, Michael L.


    We discuss a modular modelling framework to rapidly develop mathematical models of bacterial cells that would explicitly link genomic details to cell physiology and population response. An initial step in this approach is the development of a coarse-grained model, describing pseudo-chemical interactions between lumped species. A hybrid model of interest can then be constructed by embedding genome-specific detail for a particular cellular subsystem (e.g. central metabolism), called here a module, into the coarse-grained model. Specifically, a new strategy for sensitivity analysis of the cell division limit cycle is introduced to identify which pseudo-molecular processes should be delumped to implement a particular biological function in a growing cell (e.g. ethanol overproduction or pathogen viability). To illustrate the modeling principles and highlight computational challenges, the Cornell coarsegrained model of Escherichia coli B/r-A is used to benchmark the proposed framework.

  5. Mechanisms of quinidine-induced depression of maximum upstroke velocity in ovine cardiac Purkinje fibers. (United States)

    Weld, F M; Coromilas, J; Rottman, J N; Bigger, J T


    A major advance in understanding how quinidine depresses maximum upstroke velocity (Vmax) is the Hondeghem-Katzung mathematical model which incorporates voltage-independent rate constants for binding to and unbinding from resting, open, and inactive Na channels, and a voltage shift of -40 mV for the Hodgkin-Huxley h-kinetics of quinidine-associated Na channels. Using a double microelectrode voltage clamp technique to control transmembrane voltage and apply conditioning pulses, we found that quinidine blockade increased as transmembrane voltage became more positive in the range -60 to +40 mV, and that the rate of quinidine dissociation increased as transmembrane voltage became more negative in the range -60 to -140 mV. The relationship of Vmax to transmembrane voltage obtained at drive cycles from 500 msec to 20 seconds conformed to the model modified to include voltage-dependent rate constants without the postulated -40-mV shift for quinidine-associated channels. Thus binding of quinidine to inactive Na channels and unbinding from resting channels are both voltage-dependent and can explain frequency and voltage dependent actions of quinidine on Vmax without any voltage shift for quinidine-associated channels.

  6. LG Solid Oxide Fuel Cell (SOFC) Model Development

    Energy Technology Data Exchange (ETDEWEB)

    Haberman, Ben [LG Fuel Cell Systems Inc., North Canton, OH (United States); Martinez-Baca, Carlos [LG Fuel Cell Systems Inc., North Canton, OH (United States); Rush, Greg [LG Fuel Cell Systems Inc., North Canton, OH (United States)


    This report presents a summary of the work performed by LG Fuel Cell Systems Inc. during the project LG Solid Oxide Fuel Cell (SOFC) Model Development (DOE Award Number: DE-FE0000773) which commenced on October 1, 2009 and was completed on March 31, 2013. The aim of this project is for LG Fuel Cell Systems Inc. (formerly known as Rolls-Royce Fuel Cell Systems (US) Inc.) (LGFCS) to develop a multi-physics solid oxide fuel cell (SOFC) computer code (MPC) for performance calculations of the LGFCS fuel cell structure to support fuel cell product design and development. A summary of the initial stages of the project is provided which describes the MPC requirements that were developed and the selection of a candidate code, STAR-CCM+ (CD-adapco). This is followed by a detailed description of the subsequent work program including code enhancement and model verification and validation activities. Details of the code enhancements that were implemented to facilitate MPC SOFC simulations are provided along with a description of the models that were built using the MPC and validated against experimental data. The modeling work described in this report represents a level of calculation detail that has not been previously available within LGFCS.

  7. Model of cell response to {\\alpha}-particle radiation

    CERN Document Server

    Liu, Longjian


    Starting from a general equation for organism (or cell system) growth and attributing additional cell death rate (besides the natural rate) to therapy, we derive an equation for cell response to {\\alpha} radiation. Different from previous models that are based on statistical theory, the present model connects the consequence of radiation with the growth process of a biosystem and each variable or parameter has meaning regarding the cell evolving process. We apply this equation to model the dose response for {\\alpha}-particle radiation. It interprets the results of both high and low linear energy transfer (LET) radiations. When LET is high, the additional death rate is a constant, which implies that the localized cells are damaged immediately and the additional death rate is proportional to the number of cells present. While at low LET, the additional death rate includes a constant term and a linear term of radiation dose, implying that the damage to some cell nuclei has a time accumulating effect. This model ...

  8. Another brick in the cell wall: biosynthesis dependent growth model. (United States)

    Barbacci, Adelin; Lahaye, Marc; Magnenet, Vincent


    Expansive growth of plant cell is conditioned by the cell wall ability to extend irreversibly. This process is possible if (i) a tensile stress is developed in the cell wall due to the coupling effect between turgor pressure and the modulation of its mechanical properties through enzymatic and physicochemical reactions and if (ii) new cell wall elements can be synthesized and assembled to the existing wall. In other words, expansive growth is the result of coupling effects between mechanical, thermal and chemical energy. To have a better understanding of this process, models must describe the interplay between physical or mechanical variable with biological events. In this paper we propose a general unified and theoretical framework to model growth in function of energy forms and their coupling. This framework is based on irreversible thermodynamics. It is then applied to model growth of the internodal cell of Chara corallina modulated by changes in pressure and temperature. The results describe accurately cell growth in term of length increment but also in term of cell pectate biosynthesis and incorporation to the expanding wall. Moreover, the classical growth model based on Lockhart's equation such as the one proposed by Ortega, appears as a particular and restrictive case of the more general growth equation developed in this paper.

  9. Another brick in the cell wall: biosynthesis dependent growth model.

    Directory of Open Access Journals (Sweden)

    Adelin Barbacci

    Full Text Available Expansive growth of plant cell is conditioned by the cell wall ability to extend irreversibly. This process is possible if (i a tensile stress is developed in the cell wall due to the coupling effect between turgor pressure and the modulation of its mechanical properties through enzymatic and physicochemical reactions and if (ii new cell wall elements can be synthesized and assembled to the existing wall. In other words, expansive growth is the result of coupling effects between mechanical, thermal and chemical energy. To have a better understanding of this process, models must describe the interplay between physical or mechanical variable with biological events. In this paper we propose a general unified and theoretical framework to model growth in function of energy forms and their coupling. This framework is based on irreversible thermodynamics. It is then applied to model growth of the internodal cell of Chara corallina modulated by changes in pressure and temperature. The results describe accurately cell growth in term of length increment but also in term of cell pectate biosynthesis and incorporation to the expanding wall. Moreover, the classical growth model based on Lockhart's equation such as the one proposed by Ortega, appears as a particular and restrictive case of the more general growth equation developed in this paper.

  10. Modeling dynamics of HIV infected cells using stochastic cellular automaton (United States)

    Precharattana, Monamorn; Triampo, Wannapong


    Ever since HIV was first diagnosed in human, a great number of scientific works have been undertaken to explore the biological mechanisms involved in the infection and progression of the disease. Several cellular automata (CA) models have been introduced to gain insights into the dynamics of the disease progression but none of them has taken into account effects of certain immune cells such as the dendritic cells (DCs) and the CD8+ T lymphocytes (CD8+ T cells). In this work, we present a CA model, which incorporates effects of the HIV specific immune response focusing on the cell-mediated immunities, and investigate the interaction between the host immune response and the HIV infected cells in the lymph nodes. The aim of our work is to propose a model more realistic than the one in Precharattana et al. (2010) [10], by incorporating roles of the DCs, the CD4+ T cells, and the CD8+ T cells into the model so that it would reproduce the HIV infection dynamics during the primary phase of HIV infection.


    Directory of Open Access Journals (Sweden)

    D. V. Vatlitsov


    Full Text Available The technology evolution creates the prerequisites for the emergence of new informational concept and approaches to the formation of a fundamentally new principles of biological objects understanding. The aim was to study the activators of the programmed cell death in an isolated system model. Cell culture aging parameters were performed on flow cytometer. It had formed the theory that the changes in the concentrations of metal ions and increase their extracellular concentration had formed a negative gradient into the cells.regulation of cell death. It was shown that the metals ions concentrations.

  12. Cell reprogramming modelled as transitions in a hierarchy of cell cycles (United States)

    Hannam, Ryan; Annibale, Alessia; Kühn, Reimer


    We construct a model of cell reprogramming (the conversion of fully differentiated cells to a state of pluripotency, known as induced pluripotent stem cells, or iPSCs) which builds on key elements of cell biology viz. cell cycles and cell lineages. Although reprogramming has been demonstrated experimentally, much of the underlying processes governing cell fate decisions remain unknown. This work aims to bridge this gap by modelling cell types as a set of hierarchically related dynamical attractors representing cell cycles. Stages of the cell cycle are characterised by the configuration of gene expression levels, and reprogramming corresponds to triggering transitions between such configurations. Two mechanisms were found for reprogramming in a two level hierarchy: cycle specific perturbations and a noise induced switching. The former corresponds to a directed perturbation that induces a transition into a cycle-state of a different cell type in the potency hierarchy (mainly a stem cell) whilst the latter is a priori undirected and could be induced, e.g. by a (stochastic) change in the cellular environment. These reprogramming protocols were found to be effective in large regimes of the parameter space and make specific predictions concerning reprogramming dynamics which are broadly in line with experimental findings.

  13. Stem cells in animal asthma models: a systematic review. (United States)

    Srour, Nadim; Thébaud, Bernard


    Asthma control frequently falls short of the goals set in international guidelines. Treatment options for patients with poorly controlled asthma despite inhaled corticosteroids and long-acting β-agonists are limited, and new therapeutic options are needed. Stem cell therapy is promising for a variety of disorders but there has been no human clinical trial of stem cell therapy for asthma. We aimed to systematically review the literature regarding the potential benefits of stem cell therapy in animal models of asthma to determine whether a human trial is warranted. The MEDLINE and Embase databases were searched for original studies of stem cell therapy in animal asthma models. Nineteen studies were selected. They were found to be heterogeneous in their design. Mesenchymal stromal cells were used before sensitization with an allergen, before challenge with the allergen and after challenge, most frequently with ovalbumin, and mainly in BALB/c mice. Stem cell therapy resulted in a reduction of bronchoalveolar lavage fluid inflammation and eosinophilia as well as Th2 cytokines such as interleukin-4 and interleukin-5. Improvement in histopathology such as peribronchial and perivascular inflammation, epithelial thickness, goblet cell hyperplasia and smooth muscle layer thickening was universal. Several studies showed a reduction in airway hyper-responsiveness. Stem cell therapy decreases eosinophilic and Th2 inflammation and is effective in several phases of the allergic response in animal asthma models. Further study is warranted, up to human clinical trials. Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

  14. Adaptive control of 2-wheeled balancing robot by cerebellar neuronal network model. (United States)

    Tanaka, Yoshiyuki; Ohata, Yohei; Kawamoto, Tomohiro; Hirata, Yutaka


    A new adaptive motor controller was constructed, and tested on the control of a 2-wheeled balancing robot in simulation and real world. The controller consists of a feedback (PD) controller and a cerebellar neuronal network model. The structure of the cerebellar model was configured based upon known anatomical neuronal connection in the cerebellar cortex. Namely it consists of 120 granular (Gr) cells, 1 Golgi cell, 6 basket/stellate cells, and 1 Purkinje (Pk) cell. Each cell is described by a typical artificial neuron model that outputs a weighted sum of inputs after a sigmoidal nonlinear transformation. The 2 components of the proposed controller work in parallel, in a way that the cerebellar model adaptively modifies the synaptic weights between Gr and Pk as in the real cerebellum to minimize the output of the PD controller. We demonstrate that the proposed controller successfully controls a 2-wheeled balancing robot, and the cerebellar model rapidly takes over the PD controller in simulation. We also show that an abrupt load change on the robot, which the PD controller alone cannot compensate for, can be adaptively compensated by the cerebellar model. We further confirmed that the proposed controller can be applied to the control of the robot in real world.

  15. Muscle Stem Cells: A Model System for Adult Stem Cell Biology. (United States)

    Cornelison, Ddw; Perdiguero, Eusebio


    Skeletal muscle stem cells, originally termed satellite cells for their position adjacent to differentiated muscle fibers, are absolutely required for the process of skeletal muscle repair and regeneration. In the last decade, satellite cells have become one of the most studied adult stem cell systems and have emerged as a standard model not only in the field of stem cell-driven tissue regeneration but also in stem cell dysfunction and aging. Here, we provide background in the field and discuss recent advances in our understanding of muscle stem cell function and dysfunction, particularly in the case of aging, and the potential involvement of muscle stem cells in genetic diseases such as the muscular dystrophies.

  16. cellGPU: Massively parallel simulations of dynamic vertex models (United States)

    Sussman, Daniel M.


    Vertex models represent confluent tissue by polygonal or polyhedral tilings of space, with the individual cells interacting via force laws that depend on both the geometry of the cells and the topology of the tessellation. This dependence on the connectivity of the cellular network introduces several complications to performing molecular-dynamics-like simulations of vertex models, and in particular makes parallelizing the simulations difficult. cellGPU addresses this difficulty and lays the foundation for massively parallelized, GPU-based simulations of these models. This article discusses its implementation for a pair of two-dimensional models, and compares the typical performance that can be expected between running cellGPU entirely on the CPU versus its performance when running on a range of commercial and server-grade graphics cards. By implementing the calculation of topological changes and forces on cells in a highly parallelizable fashion, cellGPU enables researchers to simulate time- and length-scales previously inaccessible via existing single-threaded CPU implementations. Program Files doi: Licensing provisions: MIT Programming language: CUDA/C++ Nature of problem: Simulations of off-lattice "vertex models" of cells, in which the interaction forces depend on both the geometry and the topology of the cellular aggregate. Solution method: Highly parallelized GPU-accelerated dynamical simulations in which the force calculations and the topological features can be handled on either the CPU or GPU. Additional comments: The code is hosted at, with documentation additionally maintained at

  17. New Model of Wood Cell Wall Microfibril and Its Implications (United States)

    Umesh P. Agarwal; Sally A. Ralph; Rick S. Reiner; Carlos Baez


    Traditionally it has been accepted that the cell walls are made up of microfibrils which are partly crystalline. However, based on the recently obtained Raman evidence that showed that the interior of the microfibril was significantly disordered and water accessible, a new model is proposed. In this model, the molecular chains of cellulose are still organized along the...

  18. Modelling Morphogenesis: From Single Cells to Crawling Slugs

    NARCIS (Netherlands)

    Savill, N.J.; Hogeweg, P.


    We present a three-dimensional hybrid cellular automata (CA)/partial differential equation (PDE) model that allows for the study of morphogenesis in simple cellular systems. We apply the model to the cellular slime mold Dictyostelium discoideum "from single cells to crawling slug". Using simple loca

  19. A mouse model for oral squamous cell carcinoma

    NARCIS (Netherlands)

    R.A.L. Schoop (Remilio); M.H.M. Noteborn (Mathieu); R.J. Baatenburg de Jong (Robert Jan)


    textabstractDespite recent advances, the prognosis of oral squamous cell carcinoma is still poor. Therapeutic options such as radiotherapy, chemotherapy, surgery and the novel treatment option gene therapy are being investigated in animal models. Diverse models have been studied to induce oral squam

  20. Towards a whole-cell modeling approach for synthetic biology (United States)

    Purcell, Oliver; Jain, Bonny; Karr, Jonathan R.; Covert, Markus W.; Lu, Timothy K.


    Despite rapid advances over the last decade, synthetic biology lacks the predictive tools needed to enable rational design. Unlike established engineering disciplines, the engineering of synthetic gene circuits still relies heavily on experimental trial-and-error, a time-consuming and inefficient process that slows down the biological design cycle. This reliance on experimental tuning is because current modeling approaches are unable to make reliable predictions about the in vivo behavior of synthetic circuits. A major reason for this lack of predictability is that current models view circuits in isolation, ignoring the vast number of complex cellular processes that impinge on the dynamics of the synthetic circuit and vice versa. To address this problem, we present a modeling approach for the design of synthetic circuits in the context of cellular networks. Using the recently published whole-cell model of Mycoplasma genitalium, we examined the effect of adding genes into the host genome. We also investigated how codon usage correlates with gene expression and find agreement with existing experimental results. Finally, we successfully implemented a synthetic Goodwin oscillator in the whole-cell model. We provide an updated software framework for the whole-cell model that lays the foundation for the integration of whole-cell models with synthetic gene circuit models. This software framework is made freely available to the community to enable future extensions. We envision that this approach will be critical to transforming the field of synthetic biology into a rational and predictive engineering discipline.

  1. Induced pluripotent stem cells and Parkinson's disease: modelling and treatment. (United States)

    Xu, Xiaoyun; Huang, Jinsha; Li, Jie; Liu, Ling; Han, Chao; Shen, Yan; Zhang, Guoxin; Jiang, Haiyang; Lin, Zhicheng; Xiong, Nian; Wang, Tao


    Many neurodegenerative disorders, such as Parkinson's disease (PD), are characterized by progressive neuronal loss in different regions of the central nervous system, contributing to brain dysfunction in the relevant patients. Stem cell therapy holds great promise for PD patients, including with foetal ventral mesencephalic cells, human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs). Moreover, stem cells can be used to model neurodegenerative diseases in order to screen potential medication and explore their mechanisms of disease. However, related ethical issues, immunological rejection and lack of canonical grafting protocols limit common clinical use of stem cells. iPSCs, derived from reprogrammed somatic cells, provide new hope for cell replacement therapy. In this review, recent development in stem cell treatment for PD, using hiPSCs, as well as the potential value of hiPSCs in modelling for PD, have been summarized for application of iPSCs technology to clinical translation for PD treatment. © 2016 John Wiley & Sons Ltd.

  2. Conformon-driven biopolymer shape changes in cell modeling. (United States)

    Ji, Sungchul; Ciobanu, Gabriel


    Conceptual models of the atom preceded the mathematical model of the hydrogen atom in physics in the second decade of the 20th century. The computer modeling of the living cell in the 21st century may follow a similar course of development. A conceptual model of the cell called the Bhopalator was formulated in the mid-1980s, along with its twin theories known as the conformon theory of molecular machines and the cell language theory of biopolymer interactions [Ann. N.Y. Acad. Sci. 227 (1974) 211; BioSystems 44 (1997) 17; Ann. N.Y. Acad. Sci. 870 (1999a) 411; BioSystems 54 (2000) 107; Semiotica 138 (1-4) (2002a) 15; Fundamenta Informaticae 49 (2002b) 147]. The conformon theory accounts for the reversible actions of individual biopolymers coupled to irreversible chemical reactions, while the cell language theory provides a theoretical framework for understanding the complex networks of dynamic interactions among biopolymers in the cell. These two theories are reviewed and further elaborated for the benefit of both computational biologists and computer scientists who are interested in modeling the living cell and its functions. One of the critical components of the mechanisms of cell communication and cell computing has been postulated to be space- and time-organized teleonomic (i.e. goal-directed) shape changes of biopolymers that are driven by exergonic (free energy-releasing) chemical reactions. The generalized Franck-Condon principle is suggested to be essential in resolving the apparent paradox arising when one attempts to couple endergonic (free energy-requiring) biopolymer shape changes to the exergonic chemical reactions that are catalyzed by biopolymer shape changes themselves. Conformons, defined as sequence-specific mechanical strains of biopolymers first invoked three decades ago to account for energy coupling in mitochondria, have been identified as shape changers, the agents that cause shape changes in biopolymers. Given a set of space- and time

  3. Electrical coupling in ensembles of nonexcitable cells: modeling the spatial map of single cell potentials. (United States)

    Cervera, Javier; Manzanares, Jose Antonio; Mafe, Salvador


    We analyze the coupling of model nonexcitable (non-neural) cells assuming that the cell membrane potential is the basic individual property. We obtain this potential on the basis of the inward and outward rectifying voltage-gated channels characteristic of cell membranes. We concentrate on the electrical coupling of a cell ensemble rather than on the biochemical and mechanical characteristics of the individual cells, obtain the map of single cell potentials using simple assumptions, and suggest procedures to collectively modify this spatial map. The response of the cell ensemble to an external perturbation and the consequences of cell isolation, heterogeneity, and ensemble size are also analyzed. The results suggest that simple coupling mechanisms can be significant for the biophysical chemistry of model biomolecular ensembles. In particular, the spatiotemporal map of single cell potentials should be relevant for the uptake and distribution of charged nanoparticles over model cell ensembles and the collective properties of droplet networks incorporating protein ion channels inserted in lipid bilayers.

  4. Modeling Human Natural Killer Cell Development in the Era of Innate Lymphoid Cells (United States)

    Scoville, Steven D.; Freud, Aharon G.; Caligiuri, Michael A.


    Decades after the discovery of natural killer (NK) cells, their developmental pathways in mice and humans have not yet been completely deciphered. Accumulating evidence indicates that NK cells can develop in multiple tissues throughout the body. Moreover, detailed and comprehensive models of NK cell development were proposed soon after the turn of the century. However, with the recent identification and characterization of other subtypes of innate lymphoid cells (ILCs), which show some overlapping functional and phenotypic features with NK cell developmental intermediates, the distinct stages through which human NK cells develop from early hematopoietic progenitor cells remain unclear. Thus, there is a need to reassess and refine older models of NK cell development in the context of new data and in the era of ILCs. Our group has focused on elucidating the developmental pathway of human NK cells in secondary lymphoid tissues (SLTs), including tonsils and lymph nodes. Here, we provide an update of recent progress that has been made with regard to human NK cell development in SLTs, and we discuss these new findings in the context of contemporary models of ILC development. PMID:28396671

  5. Evolving Models of Pavlovian Conditioning: Cerebellar Cortical Dynamics in Awake Behaving Mice

    NARCIS (Netherlands)

    M. tenBrinke (MichielM.); H.J. Boele (Henk-Jan); J.K. Spanke (Jochen); J.W. Potters (Jan Willem); K. Kornysheva (Katja); P. Wulff (Peer); A.C.H.G. IJpelaar (Anna C.H.G.); S.K.E. Koekkoek (Bas); C.I. DeZeeuw (Chris)


    textabstractThree decades of electrophysiological research on cerebellar cortical activity underlying Pavlovian conditioning have expanded our understanding of motor learning in the brain. Purkinje cell simple spike suppression is considered to be crucial in the expression of conditional blink respo

  6. Aging and immortality in a cell proliferation model. (United States)

    Antal, T; Blagoev, K B; Trugman, S A; Redner, S


    We investigate a model of cell division in which the length of telomeres within a cell regulates its proliferative potential. At each division, telomeres undergo a systematic length decrease as well as a superimposed fluctuation due to exchange of telomere DNA between the two daughter cells. A cell becomes senescent when one or more of its telomeres become shorter than a critical length. We map this telomere dynamics onto a biased branching-diffusion process with an absorbing boundary condition whenever any telomere reaches the critical length. Using first-passage ideas, we find a phase transition between finite lifetime and immortality (infinite proliferation) of the cell population as a function of the influence of telomere shortening, fluctuations, and cell division.

  7. Giant vesicles "colonies": a model for primitive cell communities. (United States)

    Carrara, Paolo; Stano, Pasquale; Luisi, Pier Luigi


    Current research on the origin of life typically focuses on the self-organisation of molecular components in individual cell-like compartments, thereby bringing about the emergence of self-sustaining minimal cells. This is justified by the fact that single cells are the minimal forms of life. No attempts have been made to investigate the cooperative mechanisms that could derive from the assembly of individual compartments. Here we present a novel experimental approach based on vesicles "colonies" as a model of primitive cell communities. Experiments show that several advantages could have favoured primitive cell colonies when compared with isolated primitive cells. In fact there are two novel unexpected features typical of vesicle colonies, namely solute capture and vesicle fusion, which can be seen as the basic physicochemical mechanisms at the origin of life.

  8. Ionic channel changes in glaucomatous retinal ganglion cells: multicompartment modeling. (United States)

    Maturana, Matias I; Turpin, Andrew; McKendrick, Allison M; Kameneva, Tatiana


    This research takes a step towards discovering underlying ionic channel changes in the glaucomatous ganglion cells. Glaucoma is characterized by a gradual death of retinal ganglion cells. In this paper, we propose a hypothesis that the ionic channel concentrations change during the progression of glaucoma. We use computer simulation of a multi-compartment morphologically correct model of a mouse retinal ganglion cell to verify our hypothesis. Using published experimental data, we alter the morphology of healthy ganglion cells to replicate glaucomatous cells. Our results suggest that in glaucomatous cell, the sodium channel concentration decreases in the soma by 30% and by 60% in the dendrites, calcium channel concentration decreases by 10% in all compartments, and leak channel concentration increases by 40% in the soma and by 100% in the dendrites.

  9. Engineering models and methods for industrial cell control

    DEFF Research Database (Denmark)

    Lynggaard, Hans Jørgen Birk; Alting, Leo


    control and monitor-ing systems for production cells. The project participants are The Danish Academy of Technical Sciences, the Institute of Manufacturing Engineering at the Technical University of Denmark and ODENSE STEEL SHIPYARD Ltd.The manufacturing environment and the current practice......This paper is concerned with the engineering, i.e. the designing and making, of industrial cell control systems. The focus is on automated robot welding cells in the shipbuilding industry. The industrial research project defines models and methods for design and implemen-tation of computer based....... Further, an engineering methodology is defined. The three elements enablers, architecture and methodology constitutes the Cell Control Engineering concept which has been defined and evaluated through the implementation of two cell control systems for robot welding cells in production at ODENSE STEEL...

  10. System level modeling and component level control of fuel cells (United States)

    Xue, Xingjian

    This dissertation investigates the fuel cell systems and the related technologies in three aspects: (1) system-level dynamic modeling of both PEM fuel cell (PEMFC) and solid oxide fuel cell (SOFC); (2) condition monitoring scheme development of PEM fuel cell system using model-based statistical method; and (3) strategy and algorithm development of precision control with potential application in energy systems. The dissertation first presents a system level dynamic modeling strategy for PEM fuel cells. It is well known that water plays a critical role in PEM fuel cell operations. It makes the membrane function appropriately and improves the durability. The low temperature operating conditions, however, impose modeling difficulties in characterizing the liquid-vapor two phase change phenomenon, which becomes even more complex under dynamic operating conditions. This dissertation proposes an innovative method to characterize this phenomenon, and builds a comprehensive model for PEM fuel cell at the system level. The model features the complete characterization of multi-physics dynamic coupling effects with the inclusion of dynamic phase change. The model is validated using Ballard stack experimental result from open literature. The system behavior and the internal coupling effects are also investigated using this model under various operating conditions. Anode-supported tubular SOFC is also investigated in the dissertation. While the Nernst potential plays a central role in characterizing the electrochemical performance, the traditional Nernst equation may lead to incorrect analysis results under dynamic operating conditions due to the current reverse flow phenomenon. This dissertation presents a systematic study in this regard to incorporate a modified Nernst potential expression and the heat/mass transfer into the analysis. The model is used to investigate the limitations and optimal results of various operating conditions; it can also be utilized to perform the

  11. Computational optogenetics: empirically-derived voltage- and light-sensitive channelrhodopsin-2 model.

    Directory of Open Access Journals (Sweden)

    John C Williams

    Full Text Available Channelrhodospin-2 (ChR2, a light-sensitive ion channel, and its variants have emerged as new excitatory optogenetic tools not only in neuroscience, but also in other areas, including cardiac electrophysiology. An accurate quantitative model of ChR2 is necessary for in silico prediction of the response to optical stimulation in realistic tissue/organ settings. Such a model can guide the rational design of new ion channel functionality tailored to different cell types/tissues. Focusing on one of the most widely used ChR2 mutants (H134R with enhanced current, we collected a comprehensive experimental data set of the response of this ion channel to different irradiances and voltages, and used these data to develop a model of ChR2 with empirically-derived voltage- and irradiance- dependence, where parameters were fine-tuned via simulated annealing optimization. This ChR2 model offers: 1 accurate inward rectification in the current-voltage response across irradiances; 2 empirically-derived voltage- and light-dependent kinetics (activation, deactivation and recovery from inactivation; and 3 accurate amplitude and morphology of the response across voltage and irradiance settings. Temperature-scaling factors (Q10 were derived and model kinetics was adjusted to physiological temperatures. Using optical action potential clamp, we experimentally validated model-predicted ChR2 behavior in guinea pig ventricular myocytes. The model was then incorporated in a variety of cardiac myocytes, including human ventricular, atrial and Purkinje cell models. We demonstrate the ability of ChR2 to trigger action potentials in human cardiomyocytes at relatively low light levels, as well as the differential response of these cells to light, with the Purkinje cells being most easily excitable and ventricular cells requiring the highest irradiance at all pulse durations. This new experimentally-validated ChR2 model will facilitate virtual experimentation in neural and

  12. Mechanism of histopathological changes of nerve cells experimentally induced by chronic alcohol poisoning. (United States)

    Miyakawa, T; Sumiyoshi, S; Deshimaru, M; Hattori, E; Shikai, I


    Experimental alcoholism was produced in rats by supplying them with 15% ethanol as the only source of liquid for a whole year. Histopathological examination revealed that Purkinje cells and granule cells in the cerebellum mainly showed such changes as decrease of ER, ribosomes and severe atrophy of the nerve cells. It might be speculated that these changes were caused by the disturbance of protein synthesis in the nerve cells induced by chronic alcohol effect.

  13. Spatial modelling of brief and long interactions between T cells and dendritic cells. (United States)

    Beltman, Joost B; Marée, Athanasius F M; de Boer, Rob J


    In the early phases of an immune response, T cells of appropriate antigen specificity become activated by antigen-presenting cells in secondary lymphoid organs. Two-photon microscopy imaging experiments have shown that this stimulation occurs in distinct stages during which T cells exhibit different motilities and interactions with dendritic cells (DCs). In this paper, we utilize the Cellular Potts Model, a model formalism that takes cell shapes and cellular interactions explicitly into account, to simulate the dynamics of, and interactions between, T cells and DCs in the lymph node paracortex. Our three-dimensional simulations suggest that the initial decrease in T-cell motility after antigen appearance is due to "stop signals" transmitted by activated DCs to T cells. The long-lived interactions that occur at a later stage can only be explained by the presence of both stop signals and a high adhesion between specific T cells and antigen-bearing DCs. Furthermore, our results indicate that long-lasting contacts with T cells are promoted when DCs retract dendrites that detect a specific contact at lower velocities than other dendrites. Finally, by performing long simulations (after prior fitting to short time scale data) we are able to provide an estimate of the average contact duration between T cells and DCs.

  14. Noninvasive Assessment of Tumor Cell Proliferation in Animal Models

    Directory of Open Access Journals (Sweden)

    Matthias Edinger


    Full Text Available Revealing the mechanisms of neoplastic disease and enhancing our ability to intervene in these processes requires an increased understanding of cellular and molecular changes as they occur in intact living animal models. We have begun to address these needs by developing a method of labeling tumor cells through constitutive expression of an optical reporter gene, noninvasively monitoring cellular proliferation in vivo using a sensitive photon detection system. A stable line of HeLa cells that expressed a modified firefly luciferase gene was generated, proliferation of these cells in irradiated severe combined immunodeficiency (SCID mice was monitored. Tumor cells were introduced into animals via subcutaneous, intraperitoneal and intravenous inoculation and whole body images, that revealed tumor location and growth kinetics, were obtained. The number of photons that were emitted from the labeled tumor cells and transmitted through murine tissues was sufficient to detect 1×103 cells in the peritoneal cavity, 1×104 cells at subcutaneous sites and 1×106 circulating cells immediately following injection. The kinetics of cell proliferation, as measured by photon emission, was exponential in the peritoneal cavity and at subcutaneous sites. Intravenous inoculation resulted in detectable colonies of tumor cells in animals receiving more than 1×103 cells. Our demonstrated ability to detect small numbers of tumor cells in living animals noninvasively suggests that therapies designed to treat minimal disease states, as occur early in the disease course and after elimination of the tumor mass, may be monitored using this approach. Moreover, it may be possible to monitor micrometastases and evaluate the molecular steps in the metastatic process. Spatiotemporal analyses of neoplasia will improve the predictability of animal models of human disease as study groups can be followed over time, this method will accelerate development of novel therapeutic

  15. Molten carbonate fuel cells. Modeling, analysis, simulation, and control

    Energy Technology Data Exchange (ETDEWEB)

    Sundmacher, K.; Kienle, A. [Max-Planck-Institut fuer Dynamik Komplexer Technischer Systeme, Magdeburg (Germany); Pesch, H.J. [Bayreuth Univ. (Germany). Lehrstuhl fuer Ingenieurmathematik; Berndt, J.F. [IPF Beteiligungsgesellschaft Berndt KG, Reilingen (Germany); Huppmann, G. (eds.) [MTU CFC Solutions GmbH, Muenchen (Germany)


    This book presents model-based concepts for process analysis and control on a generalized basis. It is structured as follows: Part I - DESIGN AND OPERATION: MTU's Carbonate Fuel Cell HotModule; Operational Experiences. Part II - MODEL-BASED PROCESS ANALYSIS: MCFC Reference Model; Index Analysis of Models; Parameter Identification; Steady State Process Analysis; Hot spot formation and steady state multiplicities; Conceptual design an Reforming concepts. Part III - OPTIMIZATION AND ADVANCED CONTROL: Model reduction and State estimation; Optimal Control Strategies; Optimization of Reforming Catalyst Distribution.

  16. Dynamic Cell Formation based on Multi-objective Optimization Model

    Directory of Open Access Journals (Sweden)

    Guozhu Jia


    Full Text Available In this paper, a multi-objective model is proposed to address the dynamic cellular manufacturing (DCM formation problem. This model considers four conflicting objectives: relocation cost, machine utilization, material handling cost and maintenance cost. The model also considers the situation that some machines could be shared by more than one cell at the same period. A genetic algorithm is applied to get the solution of this mathematical model. Three numerical examples are simulated to evaluate the validity of this model.  

  17. Multi-population model of a microbial electrolysis cell. (United States)

    Pinto, R P; Srinivasan, B; Escapa, A; Tartakovsky, B


    This work presents a multi-population dynamic model of a microbial electrolysis cell (MEC). The model describes the growth and metabolic activity of fermentative, electricigenic, methanogenic acetoclastic, and methanogenic hydrogenophilic microorganisms and is capable of simulating hydrogen production in a MEC fed with complex organic matter, such as wastewater. The model parameters were estimated with the experimental results obtained in continuous flow MECs fed with acetate or synthetic wastewater. Following successful model validation with an independent data set, the model was used to analyze and discuss the influence of applied voltage and organic load on hydrogen production and COD removal.

  18. Preliminary Modeling and Simulation Study on Olfactory Cell Sensation (United States)

    Zhou, Jun; Yang, Wei; Chen, Peihua; Liu, Qingjun; Wang, Ping


    This paper introduced olfactory sensory neuron's whole-cell model with a concrete voltage-gated ionic channels and simulation. Though there are many models in olfactory sensory neuron and olfactory bulb, it remains uncertain how they express the logic of olfactory information processing. In this article, the olfactory neural network model is also introduced. This model specifies the connections among neural ensembles of the olfactory system. The simulation results of the neural network model are consistent with the observed olfactory biological characteristics such as 1/f-type power spectrum and oscillations.

  19. Modeling battery cells under discharge using kinetic and stochastic battery models