Croatian medical journal
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Croatian medical journal · Aug 2014
ReviewCerebrospinal fluid physiology: visualization of cerebrospinal fluid dynamics using the magnetic resonance imaging Time-Spatial Inversion Pulse method.
Previously there have been no methods for directly tracing the flow of cerebrospinal fluid (CSF) under physiological conditions, and the circulation of CSF has therefore been studied and visualized by injecting a radioactively labeled tracer or contrast medium visible in x-ray images. The newly developed Time-Spatial Inversion Pulse (Time-SLIP) method makes it possible to directly visualize the flow of CSF using magnetic resonance imaging (MRI), permitting CSF dynamics to be depicted in a certain time frame. ⋯ It can be said that research on CSF dynamics has advanced to the next stage with the use of this innovative imaging method. Obtaining a more accurate understanding of normal CSF physiology and pathophysiology should lead to improved diagnostic accuracy, permit the identification of new etiological factors in a variety of diseases, and promote the development of new therapeutic approaches.
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Croatian medical journal · Aug 2014
ReviewA proposed role for efflux transporters in the pathogenesis of hydrocephalus.
Hydrocephalus is a common brain disorder that is treated only with surgery. The basis for surgical treatment rests on the circulation theory. However, clinical and experimental data to substantiate circulation theory have remained inconclusive. ⋯ The location of p-gp along the pathways of macromolecular clearance and the broad substrate specificity of this abundant transporter to a variety of different macromolecules are reviewed. Involvement of p-gp in the transport of amyloid beta in Alzheimer disease and its relation to normal pressure hydrocephalus is reviewed. Finally, individual variability of p-gp expression might explain the variability in the development of hydrocephalus following intraventricular hemorrhage.
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Croatian medical journal · Aug 2014
Fluid filtration and reabsorption across microvascular walls: control by oncotic or osmotic pressure? (secondary publication).
Relationships between hydrostatic and oncotic (colloid osmotic) pressures in both capillaries and interstitium are used to explain fluid filtration and reabsorption across microvascular walls. These pressures are incorporated in the Starling oncotic hypothesis of capillaries which fails, however, to explain fluid homeostasis when hydrostatic capillary pressure is high (in feet during orthostasis) and low (in lungs), or when oncotic plasma pressure is significantly decreased in experiments and some clinical states such as genetic analbuminaemia. ⋯ The osmotic counterpressure hypothesis explains fluid homeostasis at high, mean and low capillary hydrostatic pressures. Plasma proteins and inorganic electrolytes contribute 0.4% and 94% to plasma osmolarity, respectively, so that plasma proteins have low osmotic (oncotic) pressure and despite high restriction of their passage across microvascular wall they contribute little to build up of osmotic counterpressure in comparison to electrolytes. However, absence or very low concentration of plasma proteins increases microvascular wall permeability to water and osmolytes compromising build up of osmotic counterpressure leading to development of interstial oedema.