Elasticity erythrocytes

Fig. 5.2 Immunofluorescent demonstration of smooth muscle actin (FITC, green channel) in the blood vessel wall of the human kidney. Red autofluorescence of erythrocytes, elastic lamellae and kidney tubules was captured with a filter exciting the autofluorescence in red spectrum under a longer exposure than with the filter exciting specific fluorescence in the green spectrum. Nuclei are counterstained with DAPI (blue channel)...

The human erythrocyte possesses a characteristic biconcave shape and remarkable viscoelastic properties. Electron microscopy studies performed on red blood cells (RBC), ghosts, and skeletons revealed a two-dimensional lattice of cytoskeletal proteins. This meshwork of proteins was thought to determine the elastic properties of the RBC. This... 

The membrane skeleton acts as an elastic semisolid, allowing brief periods of deformation followed by reestablishment of the original cell shape (reviewed by Bennett and Gilligan, 1993). Erythrocytes in the human bloodstream have to squeeze repeatedly through narrow capillaries of diameters smaller than their own dimensions while resisting rupture. A functional erythrocyte membrane is pivotal to maintaining the functional properties of the erythrocyte. This importance is apparent when examination is made of many hemolytic anemias, where mutation of proteins involved in the structure of the submembranous cytoskeleton, and its attachment to the lipid bilayer, result in a malformed or altered cytoskeletal architecture and a disease phenotype. 

Kuboki, M Ishii, H Kazama, M., 1990, Characterization of calpain I-binding proteins in human erythrocyte plasma membrane, J. Biochem., 107, 776-780 Kuboki, M., Ishii, H., and Kazama, M., 1987, Procalpcdn is activated on the plasma membrane and the calpain acts on the membrane, Biochim. Biophys. Acta, 929, 164—172 Labeit, S., Kolmerer, B., 1995, Titins giant proteins in charge of muscle ultrastructure and elasticity, Science, 270, 293-296... 

Kikuchi, Y. (1991). Deformability of mammalian and fish erythrocytes comparison of mean pore transit times of cells and estimation of cellular viscosity and elasticity. Jap. J. Physiol. 41, 907-922. 

A single case of severe but reversible hypoplastic anemia has been attributed to sodium diatrizoate (125). Ionic contrast media have a disaggregating effect on erythrocytes, and hyperosmolar agents reduce their elasticity (SEDA-22, 501). When blood is diluted with 90% sodium diatrizoate in vitro, there is initially a reduction in... 

It is useful, for reasons which are apparent in relation to movement of nanoparticles in vivo, to divide nanosystems into two types, hard and soft, although there are obviously intermediate situations. Hard systems, for example, polymeric nanoparticles and nanocapsules, nanosuspensions or nanocrystals, dendrimers, and carbon nanotubes are neither flexible nor elastic. Hard systems can block capillaries and fenestrae that have dimensions similar to the particles, whereas soft systems can deform and reform to varying degrees. Erythrocytes and many liposomes fall into this category and are thus better able to navigate capillary beds and tissue extracellular spaces. Soft systems include nanoemulsions (microemulsions) and polymeric micelles. 

A typical microcapsule containing 10% by volume of guinea pig red blood cells and prepared from polymers 3 and 12 is illustrated in Fig. 26 (1 II). The capsule wall was elastic and resisted puncture with a fine needle. [Such capsules (without cells) were stored intact for over six months in our laboratory]. The erythrocytes remained bright red over an 8 day storage period and retained the... 

DNIC with Thiol-Containing Ligands Increase Erythrocyte Elasticity... 

Obviously, increased elasticity of animal and hiunan erythrocytes provides their intensive traffic through the capillary network and thus improves micro-circulation and the blood supply of cells and tissues. Moreover, DNIC with glutathione notably enhance microcirculation in animals with hemorrhagic shock by virtue of their ability to enhance elastic properties of blood erythrocytes [52]. 

To predict the shape of an adherent tissue cell and quantify the stress distribution inside it, the fibrous actin cytoskeleton or the ECM can be modeled as a two-dimensional network of elastic cables. Previously, elastic cable network provided remarkable quantitative predictions of erythrocyte elastic properties and micropipette aspiration experiments. The cable networks have the additional feature that filaments buckle under compressive load. This model has already been tested successfully to model cell poking, magnetic twisting cytometry, magnetic bead microrheometry experiments. Although the cable network is far from representing the complexity of the actin network mechanics, it incorporates some of its essential features. This model is extended to include the effect of spatial distribution of adhesion points along the periphery of the cell. 

A wide variety of shape transformations of fluid membranes has been extensively studied theoretically in the past two decades using a bending elasticity model proposed by Canham and Helfrich [1]. The model has succeeded in explaining equilibrium shapes of the erythrocyte. However, much attention has recently been paid to shape deformations induced by internal degrees of freedom of membranes. For example, the bending elasticity model cannot explain the deformation from the biconcave shape of the erythrocyte to the crenated one (echinocytosis) [2, 3]. It is pointed out [3] that a local asymmetry in the composition between two halves of the bilayer plays an important role in the crenated shape. It has been observed [4] that a lateral phase separation occurs on an artificial two-component membrane where domains prefer local curvatures depending on the composition. In order to study the shape deformation accompanied by the intramembrane phase separation, we consider a two-component membrane as the simplest case of real biomembranes composed of several kinds of amphiphiles. 

Strey, H., Peterson, M. and Sackmann, E. (1995) Measurement of erythrocyte membrane elasticity by flicker eigenmode decomposition. Biophysical Journal, 69, 478-88. 

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