• The BBB separates the blood from the extracellular cerebrospinal fluid and protects the brain from bloodborne pathogens and toxins while allowing the diffusion of oxygen, carbon dioxide, and small lipophilic molecules/ethanol [ 4 ]. (hindawi.com)
  • The transport may be active transport by carrier proteins with an energy source, or it may be facilitated diffusion or passive transport via channels. (wikibooks.org)
  • Polar compounds cannot diffuse across these cell membranes and the uptake of useful molecules is mediated through transport proteins that specifically select substrates from the extracellular mixture. (bionity.com)
  • Free-water imaging is a new methodology that is sensitive to water molecules diffusing in the extracellular space. (nih.gov)
  • All cells need to acquire the molecules and ions that they need from their surrounding extracellular fluid. (wikibooks.org)
  • When ΔG is positive the transport is active, an input of energy is needed to move a molecule up a concentration gradient, contrary to ΔG being negative the transport is passive, which means that such molecules will pass through a membrane down their own gradient, simple diffusion. (wikibooks.org)
  • Diffusion is the process by which molecules migrate over the cell membrane from areas of higher concentration to areas of lower concentration. (wikibooks.org)
  • 1) Tracer diffusion is the spontaneous mixing of molecules that occurs in absence of a concentration gradient. (wikibooks.org)
  • Diffusion, or brownian movement, denotes the random motion of molecules. (medscape.com)
  • Random motion of water molecules (diffusion) in the presence of a strong magnetic gradient results in MR signal loss as a result of the dephasing of spin coherence ( Fig. 1 ). (ajronline.org)
  • The application of a pair of strong gradients to elicit differences in the diffusivity of water molecules among various biologic tissues is known as diffusion sensitization or diffusion weighting [ 22 , 23 ]. (ajronline.org)
  • Diagram shows loss of intensity of MR signal (S, solid line ) resulting from inefficient rephasing of dephased spins because of displacement of water molecules (diffusion) between application of bipolar gradients ( G ). With decreased diffusion (reduced displacement of water molecules), rephasing process is more efficient and signal loss is predominantly caused by T2 decay ( dotted line ). (ajronline.org)
  • Being a semipermeable membrane, both the BBB and BSCB allow the diffusion of certain molecules, whilst restricting others. (hindawi.com)
  • By measuring the self-diffusion of molecules in biological tissues, we obtain information about microscopic structures that are too small to resolve in conventional images. (lu.se)
  • A computational reaction–diffusion model for biosynthesis and linking of cartilage extracellular matrix in cell-seeded scaffolds with varying porosity. (ncsu.edu)
  • In the adult vertebrate brain, enzymatic removal of the extracellular matrix (ECM) is increasingly recognized to promote learning, memory recall, and restorative plasticity. (nature.com)
  • In the vertebrate brain, long-lasting structural tenacity of neuronal networks is supported by the extracellular matrix (ECM). (nature.com)
  • Influence of the extracellular matrix on water mobility in subcortical gray matter. (mpg.de)
  • Investigation of the influence of the extracellular matrix on water diffusion in brain and cartilage. (mpg.de)
  • Possible contribution of the extracellular matrix to the MRI contrast in the brain. (mpg.de)
  • Observing the hyaluronan component of the extracellular matrix in the brain with quantitative MRI. (mpg.de)
  • Historically, multicellular bacterial communities, known as biofilms, have been thought to be held together solely by a self-produced extracellular matrix. (nature.com)
  • Biofilms are multicellular communities that were so far thought to be held together solely by a self-produced organic extracellular matrix. (nature.com)
  • Organic extracellular matrix production as a means of cell-cell and cell-substrate adhesion has been extensively studied. (nature.com)
  • We demonstrate that a mature 3D structure of mineral scaffolds holds the extracellular matrix and the bacterial cells together. (nature.com)
  • Because ECV defines the proportion of a volume of tissue that consists of extracellular matrix or space between myocytes, it is a marker of myocardial tissue remodeling. (medscape.com)
  • 1 . Halnes G, Mäki-Marttunen T, Keller D, Pettersen KH, Andreassen OA, Einevoll GT (2016) Effect of Ionic Diffusion on Extracellular Potentials in Neural Tissue. (yale.edu)
  • High angular resolution susceptibility and diffusion imaging in post mortem chimpanzee brain: Tensor characteristics and similarities. (mpg.de)
  • [ 1 , 2 ] Imaging and interpretation of water diffusion have improved with the development of diffusion tensor imaging (DTI). (medscape.com)
  • Diffusion tensor imaging has shown strong momentum in research performed to evaluate the neural fibers of the central nervous system (CNS). (medscape.com)
  • Diffusion tensor imaging can be used to measure anisotropy per voxel and provides directional information relevant for magnetic resonance tractography or fiber tracking in vivo. (medscape.com)
  • Diffusion tensor imaging allows direct examination of the brain microstructure and has become a useful tool for investigating brain disorders such as stroke, epilepsy, multiple sclerosis (MS), brain tumors, and demyelinating and dysmyelinating disorders. (medscape.com)
  • In this paper, we briefly describe the tensor theory used to characterize molecular diffusion in white matter and how the tensor elements are measured experimentally using diffusion-sensitive MR imaging. (ajronline.org)
  • We then review techniques for acquiring relatively high-resolution diffusion-sensitive MR images and computer-based algorithms that allow the generation of white matter fiber tract maps from the tensor data. (ajronline.org)
  • Diffusion tensor imaging was used to detect structural abnormalities in the cBF system. (bvsalud.org)
  • Diffusion tensor distribution imaging of an in vivo mouse brain at ultra-high magnetic field by spatiotemporal encoding. (lu.se)
  • Diffusion tensor distribution imaging. (lu.se)
  • Tensor-valued diffusion MRI in under 3 minutes: an initial survey of microscopic anisotropy and tissue heterogeneity in intracranial tumors. (lu.se)
  • Used in LGE assessment, gadolinium is an extracellular chelating agent that permeates the interstitial space of both normal and abnormal myocardium . (medscape.com)
  • These oscillations (1-2 mM) are synchronous with the burst pattern, and apparently are caused by the oscillating voltage-dependent membrane currents: Extracellular K+ concentration (Ke) rises during the depolarized active (spiking) phase and falls during the hyperpolarized silent phase. (nyu.edu)
  • Osmosis is the diffusion of water through a semi-permeable membrane. (wikibooks.org)
  • The most common CA used in T 1 -weighted DCE-MRI, Gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA), is able to transverse the vascular endothelium (except when the blood-brain barrier is intact) and enter the extravascular-extracellular space (EES), but is unable to cross the cellular membrane. (biomedcentral.com)
  • [2] In contrast, the diffusion of hydrophobic compounds across these barriers cannot be controlled and organisms therefore cannot exclude lipid -soluble xenobiotics using membrane barriers. (bionity.com)
  • The process restores the excess of intracellular potassium and extracellular sodium and reinstates the negative resting membrane potential. (medscape.com)
  • Hair cells have a bundle of elongated microvilli called stereocilia that project from the apical membrane into an extracellular gelatinous material that overlies the sensory area in each vestibular organ. (cdc.gov)
  • The hepatocyte-to-extracellular concentration ratio measured at this time point was much higher during MEB perfusion. (aspetjournals.org)
  • normal states and abnormal conditions are easily interpreted through the use of DWI in conjunction with apparent diffusion coefficient (ADC) imaging by correlating findings of hyperintensity on DWI images with findings of hypointensity on ADC images (see the images below). (medscape.com)
  • On DWI commonly used to diagnose acute stroke (see the image below), diffusion is described by using the apparent diffusion coefficient (ADC). (medscape.com)
  • Extracellular Vesicles: Goodies for the Brain? (helmholtz-hzi.de)
  • Diffusion-weighted imaging has been shown to be useful in the investigation of brain disorders such as epilepsy , multiple sclerosis , brain abscesses , brain tumors, mild traumatic brain injury, and hypertensive encephalopathy (see the images below). (medscape.com)
  • Axial fluid-attenuated inversion recovery (FLAIR) image (top left), diffusion-weighted image (DWI) (top right), and axial and sagittal T1-weighted (T1W) images (bottom) in a 40-year-old man with a history of intravenous drug abuse and fever demonstrate multiple enhancing focal brain lesions in the gray-white matter junction (arrow) compatible with septic emboli. (medscape.com)
  • The ability to spatially map the diffusion of free water protons in vivo using 1 H MR imaging and the observation that the diffusion of free water protons is reduced in acutely infarcted brain tissue are responsible for the widespread use of these techniques in clinical imaging [ 3 , 4 , 5 , 6 , 7 , 8 ]. (ajronline.org)
  • Towards non-parametric diffusion-T1 characterization of crossing fibers in the human brain. (lu.se)
  • Computing and visualising intra-voxel orientation-specific relaxation-diffusion features in the human brain. (lu.se)
  • This active transport creates a concentration gradient that favors the extracellular diffusion of potassium ions. (medscape.com)
  • A diffusion coefficient is a factor of proportionality that represents the amount of substance diffusion across a unit area through a unit concentration gradient in unit time. (wikibooks.org)
  • To provide information on extracellular water accumulation, free-water fraction (FWf) was quantified. (bvsalud.org)
  • Cephalosporins penetrate well into most body fluids and the extracellular fluid of most tissues, especially when inflammation (which enhances diffusion) is present. (msdmanuals.com)
  • A cell's activity depends on what biochemical reactions it may complete, and these reactions are dependent on the compounds extracted from the extracellular fluid. (wikibooks.org)
  • Axial diffusion-weighted image (DWI) (top left), T2-weighted (T2W) image (top right), fluid-attenuated inversion recovery (FLAIR) image (bottom left), and contrast-enhanced T1W (bottom right) image demonstrate a right convexity meningioma, which appears hypointense on DWI image. (medscape.com)
  • In contrast, traditional models predict that the signal presentation from the source via free secretion and extracellular diffusion is a non-selective process. (biorxiv.org)
  • Contrast-enhanced T1 mapping is mostly used for calculating extracellular volume fraction (ECV) - that is, the ratio of pre- and postcontrast myocardial T1 to that of the ventricular blood compartment T1. (medscape.com)
  • Acquiring diffusion-weighted images with at least two different b values (commonly 20 and 1000 sec/mm 2 ) while keeping the TE fixed allows the determination of the ADC value for each image voxel ( Fig. 3 ). (ajronline.org)
  • Establishing and maintaining the air-liquid interface needs balanced ion and water transport as well as an appropriate paracellular barrier that ensures diffusion of solvent and solute between airway surface and interstitium while preventing uncontrolled leakage. (springer.com)
  • Extending NEURON to handle reaction-diffusion problems. (yale.edu)
  • Diffusion in structured tissue such as white matter is anisotropic. (medscape.com)
  • Multidimensional encoding of restricted and anisotropic diffusion by double rotation of the q vector. (lu.se)
  • Multidimensional correlation of nuclear relaxation rates and diffusion tensors for model-free investigations of heterogeneous anisotropic porous materials. (lu.se)
  • We applied free-water imaging on diffusion MRI data acquired from schizophrenia-diagnosed human subjects with a first psychotic episode. (nih.gov)
  • Even though the thickness of the myelin sheath is in the order of micrometres, well beyond the MRI spatial resolution, its presence influences several physical properties that can be probed with MRI, from longitudinal and transversal relaxation phenomena to water molecule diffusion processes. (biorxiv.org)
  • However, water diffuses asymmetrically in the white matter-that is, diffusion is restricted perpendicular to the long axis of the axons. (medscape.com)
  • have developed a mathematical model of a public goods dilemma within a microbial colony, in which the public good travels from its producers to other cells by diffusion. (cdc.gov)
  • Diffusion MRI has been successful in identifying the existence of white matter abnormalities in schizophrenia in vivo. (nih.gov)
  • Diffusion-weighted imaging (DWI) is a well-established magnetic resonance imaging (MRI) method for diagnosing cerebral ischemia. (medscape.com)
  • In the last 10-15 years, MR imaging techniques have been increasingly applied to the study of molecular displacement (diffusion) in biologic tissue [ 1 , 2 ]. (ajronline.org)
  • Effects of imaging gradients in sequences with varying longitudinal storage time - case of diffusion exchange imaging. (lu.se)
  • Accuracy and precision of statistical descriptors obtained from multidimensional diffusion signal inversion algorithms. (lu.se)
  • Diffusion MRI is a powerful non-invasive method for studying molecular motion on the micrometer length scale and millisecond time scale. (lu.se)
  • Cell-derived extracellular vesicles are important intercellular communicators involved in many biological processes and diseases, including cancer and cardiovascular diseases, but, thus far, how they navigate within complex extracellular matrices has been poorly understood. (helmholtz-hzi.de)
  • Previous theory suggests that spatial structure can promote evolution of cooperation, but the diffusion of public goods introduces new phenomena that must be modeled explicitly. (cdc.gov)
  • The results of our model suggest that diffusion of extracellular K+ may contribute to coupling and synchronization of electrical oscillations in beta-cells within an islet. (nyu.edu)
  • Stokes, CL & Rinzel, J 1993, ' Diffusion of extracellular K+ can synchronize bursting oscillations in a model islet of Langerhans ', Biophysical journal , vol. 65, no. 2, pp. 597-607. (nyu.edu)
  • The model predicts that cooperation is favored when the diffusion rate is small, when the colonies are flatter, and when the public goods decay slowly. (cdc.gov)
  • Adding diffusion-sensitizing gradients to an imaging sequence (spatial encoding) constitutes the basis for diffusion-weighted MR imaging. (ajronline.org)
  • Massively multidimensional diffusion-relaxation correlation MRI. (lu.se)
  • Excessive extracellular volume is a surrogate biomarker for neuroinflammation and can be separated out to reveal abnormalities such as axonal degeneration that affect diffusion characteristics in the tissue. (nih.gov)
  • has made it a stand-alone method for chemical hazard ics from the left and right side of the head emptying into the venous system independently (similar to human anatomy), and that chemical diffusion/absorption would be insignificant with Corresponding author. (cdc.gov)
  • Livers were preperfused with gadopentetate dimeglumine to measure extracellular concentrations. (aspetjournals.org)
  • Opening of the intracellular gate involves a hinge-like movement of TM1a and the partial unwinding of TM5, which together create a permeation pathway that enables substrate and ion diffusion to the cytoplasm. (rcsb.org)
  • The beta-cells also share an extracellular compartment in which oscillations of K+ concentration have been measured (Perez-Armendariz and Atwater, 1985). (nyu.edu)
  • Standard methods, such as volume-conductor theory and current-source density theory, assume that diffusion has a negligible effect on the ECS potential, at least in the range of frequencies picked up by most recording systems. (yale.edu)
  • We found a significant increase in the extracellular volume in both white and gray matter. (nih.gov)
  • Other important factors include rates of diffusion and decay of the public good-both of which affect how widely the public good is shared. (cdc.gov)