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Rheology of the Hemolytic Anemias
Published in Gordon D. O. Lowe, Clinical Blood Rheology, 2019
The area relationship of the inner and outer leaflets of the bilayer is important and is known as the bilayer couple hypothesis.22 A small expansion of the outer leaflet relative to the inner will generate the echinocyte shape while relative expansion of the inner leaflet will produce a stomatocyte.23 Erythrocyte shape may be determined primarily by the lipid bilayer with the determined shape becoming secondarily stabilized by the protein skeleton.24 Any modulatory role of calmodulin25 in this respect is still debatable.
Section I
Published in Evan A. Evans, Richard Skalak, Mechanics and Thermodynamics of Biomembranes, 1980
Another important aspect of the behavior of biological membranes, which is different from that of macroscopic isotropic materials, is the strong effects of the chemical environment on the shape and properties of cell membranes. In the case of the red blood cell, a range of shapes is observed, including the normal biconcave shape (discocyte), cup shape (stomatocyte), tightly crenated spherical shape (echinocyte), and many other variations which depend on the chemical environment surrounding the cell. Reversible changes of red blood cell shape were first described by Hamburger in 1895.36 In the 1930s, Ponder (1971)68 accumulated a vast amount of information on the multiplicity of agents and conditions which induce these transformations. Extensive observations of the specific chemical agents and the shapes that they produce have been assembled by Bessis (1973).3
Factors affecting the morphology of some organic and inorganic nanostructures for drug delivery: characterization, modifications, and toxicological perspectives
Published in Expert Opinion on Drug Delivery, 2020
Ruchira Raychaudhuri, Abhjieet Pandey, Aswathi Hegde, Shaik Mohammad Abdul Fayaz, Dinesh Kumar Chellappan, Kamal Dua, Srinivas Mutalik
Tetra-ethyleneglycol mono hexa-decyl ether (C16E4) in D2O shows lamellar liquid crystalline phase in the absence of shear and upon induction, with shear, the system converts to multilamellar vesicular system probably through a multilamellar cylinder formation [17]. In a similar work by the same group using pentaethylene glycol monododecyl ether (C12E5) in D2O, planar lamellar phase converts to multilamellar vesicles (MLV) under shear flow at 55 °C [42]. Further insight into the transformations was provided through this study where they used time-resolved small-angle neutron scattering to explain the lamellar to MLV transition through buckle formation. The cationic surfactant diethylesterdimethyl ammonium chloride was used to prepare vesicle suspensions which were shown to transform even in the absence of external triggers [43]. The transition depends on the concentration of the surfactant and the salt concentration which is driven by repulsion between charged vesicles. This repulsiveness is strong enough to drive the transformation of unilamellar vesicles to multilamellar ones by deflation through stomatocyte and doublet formations. For low surfactant concentrations at a fixed salt concentration, the unilamellar vesicles remain as such and do not form doublets. On an increase in surfactant concentration, the deflation from unilamellar to multilamellar vesicles takes place due to the ‘crowding hypothesis’. At low salt concentrations, the repulsion is more between the vesicles and they deflate more.
The role of hydrophobic /hydrophilic balance in the activity of structurally flexible vs. rigid cytolytic polypeptides and analogs developed on their basis
Published in Expert Review of Proteomics, 2018
Peter V. Dubovskii, Roman G. Efremov
Modifications of Ltc 1 peptide with an additional Lys residue at the C-terminus (Ltc1-K) were studied (#7, Table 1). The peptides lacked either a single, a pair, or three N-terminal residues [66]. The corresponding peptides are denominated (−1)Ltc1-K, (−2)Ltc1-K, and (−3)Ltc1-K, respectively (#8–10, Table 1). The shortest analog, (−3)Ltc1-K (#10, Table 1), contrary to the respective one of Ltc 2a peptide (#4, Table 1), exhibited not a complete loss of hemolytic activity. Specifically, at the concentration of 10 µM, Ltc1-K peptide induced 100% hemolysis of human RBC, while (−3)Ltc1-K exhibited only 60%, the maximum value from all the shortened analogs of this peptide. At concentration of ~ 15 µM, the both parent peptides Ltc1-K and (−3)Ltc1-K analog exhibited 100% hemolysis and induced transformations of erythrocytes from their intact shape successively to echinocytes, stomatocyte, spherocyte, and ghosts. This shows that hemolysis is not necessarily due to the N-terminal residues of the peptides, as suggested earlier [79].
Effects of membrane reference state on shape memory of a red blood cell
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Zhe Gou, Xiaodong Ruan, Feng Huang, Xin Fu
The present study mainly focuses on the recovery response started from an elongated discocyte. In shear flow, the cell is observed to show other shapes like stomatocyte, trilobe, hexalobe, etc. (Lanotte et al. 2016). After leaving a constriction the cell adopts a parachute shape (Braunmuller et al. 2012). The recovery response from these shapes may demonstrate other properties of the membrane that help determine both the RSC and the RSL. For these purposes, further numerical and experimental studies on the recovery response of RBCs are needed in future works.