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Diffusion

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Cellular Dynamic Simulator: An Event Driven Molecular Simulation Environment For Cellular Physiology, Michael J Byrne, M Neal Waxham, Yoshihisa Kubota Jun 2010

Cellular Dynamic Simulator: An Event Driven Molecular Simulation Environment For Cellular Physiology, Michael J Byrne, M Neal Waxham, Yoshihisa Kubota

Journal Articles

In this paper, we present the Cellular Dynamic Simulator (CDS) for simulating diffusion and chemical reactions within crowded molecular environments. CDS is based on a novel event driven algorithm specifically designed for precise calculation of the timing of collisions, reactions and other events for each individual molecule in the environment. Generic mesh based compartments allow the creation / importation of very simple or detailed cellular structures that exist in a 3D environment. Multiple levels of compartments and static obstacles can be used to create a dense environment to mimic cellular boundaries and the intracellular space. The CDS algorithm takes into …


Structural Plasticity Can Produce Metaplasticity, Georgios Kalantzis, Harel Z Shouval Jan 2009

Structural Plasticity Can Produce Metaplasticity, Georgios Kalantzis, Harel Z Shouval

Journal Articles

BACKGROUND: Synaptic plasticity underlies many aspect of learning memory and development. The properties of synaptic plasticity can change as a function of previous plasticity and previous activation of synapses, a phenomenon called metaplasticity. Synaptic plasticity not only changes the functional connectivity between neurons but in some cases produces a structural change in synaptic spines; a change thought to form a basis for this observed plasticity. Here we examine to what extent structural plasticity of spines can be a cause for metaplasticity. This study is motivated by the observation that structural changes in spines are likely to affect the calcium dynamics …


Brain Fiber Tract Plasticity In Experimental Spinal Cord Injury: Diffusion Tensor Imaging, Jaivijay Ramu, Juan Herrera, Raymond Grill, Tobias Bockhorst, Ponnada Narayana Jul 2008

Brain Fiber Tract Plasticity In Experimental Spinal Cord Injury: Diffusion Tensor Imaging, Jaivijay Ramu, Juan Herrera, Raymond Grill, Tobias Bockhorst, Ponnada Narayana

Journal Articles

Diffusion tensor imaging (DTI) and immunohistochemistry were performed in spinal cord injured rats to understand the basis for activation of multiple regions in the brain observed in functional magnetic resonance imaging (fMRI) studies. The measured fractional anisotropy (FA), a scalar measure of diffusion anisotropy, along the region encompassing corticospinal tracts (CST) indicates significant differences between control and injured groups in the 3 to 4 mm area posterior to bregma that correspond to internal capsule and cerebral peduncle. Additionally, DTI-based tractography in injured animals showed increased number of fibers that extend towards the cortex terminating in the regions that were activated …


Quantitative Diffusion Tensor Imaging Detects Dopaminergic Neuronal Degeneration In A Murine Model Of Parkinson's Disease, Michael D Boska, Khader M Hasan, Danette Kibuule, Rebecca Banerjee, Erin Mcintyre, Jay A Nelson, Theresa Hahn, Howard E Gendelman, R Lee Mosley Jun 2007

Quantitative Diffusion Tensor Imaging Detects Dopaminergic Neuronal Degeneration In A Murine Model Of Parkinson's Disease, Michael D Boska, Khader M Hasan, Danette Kibuule, Rebecca Banerjee, Erin Mcintyre, Jay A Nelson, Theresa Hahn, Howard E Gendelman, R Lee Mosley

Journal Articles

Early diagnosis of Parkinson's disease (PD) is required to improve therapeutic responses. Indeed, a clinical diagnosis of resting tremor, rigidity, movement and postural deficiencies usually reflect >50% loss of the nigrostriatal system in disease. In a step to address this, quantitative diffusion tensor magnetic resonance imaging (DTI) was used to assess nigrostriatal degeneration in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication model of dopaminergic nigral degeneration. We now demonstrate increased average diffusion (p


Computer Simulation Of Glioma Growth And Morphology., Hermann B. Frieboes, John S Lowengrub, S Wise, X Zheng, Paul Macklin, Elaine L. Bearer, Vittorio Cristini Jan 2007

Computer Simulation Of Glioma Growth And Morphology., Hermann B. Frieboes, John S Lowengrub, S Wise, X Zheng, Paul Macklin, Elaine L. Bearer, Vittorio Cristini

Journal Articles

Despite major advances in the study of glioma, the quantitative links between intra-tumor molecular/cellular properties, clinically observable properties such as morphology, and critical tumor behaviors such as growth and invasiveness remain unclear, hampering more effective coupling of tumor physical characteristics with implications for prognosis and therapy. Although molecular biology, histopathology, and radiological imaging are employed in this endeavor, studies are severely challenged by the multitude of different physical scales involved in tumor growth, i.e., from molecular nanoscale to cell microscale and finally to tissue centimeter scale. Consequently, it is often difficult to determine the underlying dynamics across dimensions. New techniques …


Noninvasive Assessment Of Diffusion Hypoxia Following Administration Of Nitrous Oxide-Oxygen, Arthur H. Jeske, Clark W. Whitmire, Chris Freels, Mike Fuentes Jan 2004

Noninvasive Assessment Of Diffusion Hypoxia Following Administration Of Nitrous Oxide-Oxygen, Arthur H. Jeske, Clark W. Whitmire, Chris Freels, Mike Fuentes

Journal Articles

The phenomenon of diffusion hypoxia is commonly believed to occur unless nitrous oxide-oxygen inhalation sedation is followed by "washout" with 100% oxygen for 5 minutes upon termination of the flow of nitrous oxide. When systematically studied, however, this phenomenon generally appears to be unfounded. The present study evaluated the effect of breathing room air instead of 100% oxygen in healthy (ASA 1) human volunteers following administration of sedative concentrations of nitrous oxide. The occurrence of hypoxia was determined objectively, using pulse oximetry and a standardized psychomotor skills test (Trieger test). Diffusion hypoxia was not observed using these criteria.