Ivan Voříšek

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Diffusion anisotropy was investigated in the developing rat brain [postnatal day (P)6-29] with the use of ion-selective microelectrodes to measure the three-dimensional distribution of tetramethylammonium (TMA+) iontophoresed into the extracellular space (ECS). The diffusion parameters, ECS volume fraction alpha (alpha = ECS volume/total tissue volume),(More)
Changes in the ability of substances to diffuse in the intersticial space of the brain are important factors in the pathophysiology of cerebrovascular diseases. Extracellular space (ECS) volume fraction alpha (alpha = ECS volume/ total tissue volume), tortuosity lambda (lambda 2 = free diffusion coefficient/apparent diffusion coefficient), and nonspecific(More)
To obtain a better understanding of the mechanisms underlying early changes in the brain water apparent diffusion coefficient (ADC) observed in cerebral ischemia, dynamic changes in the ADC of water and in the energy status were measured at postnatal day 8 or 9 in neonatal rat brains after cardiac arrest using 1H MRS/MRI and 31P MRS, respectively. The time(More)
The diffusion parameters in rat cortex were studied 3-35 days following a cortical stab wound, using diffusion-weighted MR to determine the apparent diffusion coefficient of water (ADC(W)) in the tissue, and the real-time iontophoretic tetramethylammonium (TMA) method to measure the extracellular space (ECS) diffusion parameters: ECS volume fraction alpha(More)
At the nodes of Ranvier, excitable axon membranes are exposed directly to the extracellular fluid. Cations are accumulated and depleted in the local extracellular nodal region during action potential propagation, but the impact of the extranodal micromilieu on signal propagation still remains unclear. Brain-specific hyaluronan-binding link protein, Bral1,(More)
Aquaporin-4 (AQP4) is the primary cellular water channel in the brain and is abundantly expressed by astrocytes along the blood-brain barrier and brain-cerebrospinal fluid interfaces. Water transport via AQP4 contributes to the activity-dependent volume changes of the extracellular space (ECS), which affect extracellular solute concentrations and neuronal(More)
Whole cell patch-clamp recordings of K+ currents from oligodendrocyte precursors in 10-day-old rats (P10) and, following myelination, in mature oligodendrocytes from 20-day-old rats (P20) were correlated with extracellular space (ECS) diffusion parameters measured by the local diffusion of iontophoretically injected tetramethylammonium ions (TMA+). The aim(More)
The extracellular space (ECS) diffusion parameters influence the movement of ions, neuroactive substances, hormones and metabolites in the nervous tissue. They also affect extrasynaptic transmission, a mode of signal transmission dependent solely on diffusion. This review compares in detail two methods for studying diffusion in the brain: the real-time(More)
Tenascin-R (TN-R), a large extracellular glycoprotein, is an important component of the adult brain's extracellular matrix (ECM); tenascin-C (TN-C) is expressed mainly during early development, while human natural killer 1 (HNK-1) is a sulphated carbohydrate epitope that attaches to these molecules, modifying their adhesive properties. To assess their(More)