scholarly journals Selective flow-induced vesicle rupture to sort by membrane mechanical properties

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Angelo Pommella ◽  
Nicholas J. Brooks ◽  
John M. Seddon ◽  
Valeria Garbin
Keyword(s):  
Mechanical Properties ◽  
Vesicle Rupture ◽  
Membrane Mechanical Properties

scholarly journals Transversal Otolithic Membrane Deflections Evoked by the Linear Accelerations

2019 ◽  
Vol 12 (1) ◽  
pp. 46
Author(s):  
Valeri Goussev
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Steady State ◽  
Elasticity Theory ◽  
Membrane Structure ◽  
Middle Section ◽  
Otolith Organ ◽  
2D Elasticity ◽  
2D Space ◽  
Membrane Mechanical Properties

Considered is the model of the transversal utricle membrane deflections evoked by the linear accelerations. The basic idea underlying this consideration is that the linear accelerations can cause both longitudinal and transversal deformations when acting along the membrane in the buckling way. The real 3D utricle membrane structure was simplified by considering its middle section and evaluating its elastic properties in 2D space. The steady state transversal deflections along the membrane are analytically evaluated and numerically simulated using the 2D elasticity theory. The transversal deflections are found to be more expressive and stronger as compared to the conventional longitudinal deformations. The maxima of longitudinal deformations and transversal deflections are observable in different regions of the utricle membrane. The revealed properties could be used for explanation of the transduction processes in the otolith organ. Based on the implemented modeling approach the new otolithic membrane mechanical properties are discussed and new explanations for the available experimental data are given.

scholarly journals Mechanical properties of sickle cell membranes

Blood ◽  
1990 ◽  
Vol 75 (8) ◽  
pp. 1711-1717 ◽  
Author(s):  
R Messmann ◽  
S Gannon ◽  
S Sarnaik ◽  
RM Johnson
Keyword(s):  
Mechanical Properties ◽  
Blood Cell ◽  
Sickle Cell ◽  
Red Blood Cell ◽  
Cell Membranes ◽  
Erythrocyte Membranes ◽  
Sickle Cells ◽  
Dense Cell ◽  
Cell Fractions ◽  
Membrane Mechanical Properties

Abstract The mechanical properties of sickle erythrocyte membranes were evaluated in the ektacytometer. When ghosts from the total red blood cell population were examined, the rigidity of the resealed ghosts and their rate of fragmentation by shear stress (t1/2) were normal. However, fractionation on Stractan density gradients revealed that sickle cells were heterogenous in their membrane mechanical properties. The ghosts from dense cell fractions exhibited both increased rigidity and decreased stability. Presumably, these altered mechanical properties are a reflection of the well-documented biochemical damage found in irreversibly sickle cell membranes. Nevertheless, neither of the alterations in mechanical properties are likely to be significant elements in the hemolysis of sickle cell anemia. Earlier studies of abnormal erythrocytes suggest that increases in membrane rigidity per se do not increase hemolysis, and they are, therefore, unlikely to do so in this case. The stability of membranes from the dense cell fractions was reduced to about two thirds of the control value. Comparison with the results of studies of red blood cell membranes with genetically defective or deficient spectrin suggests that a reduction in t 1/2 of 50% is not associated with significant increases in the rate of hemolysis. Although altered ghost stability and flexibility can be demonstrated in dense sickle cells, these changes in membrane mechanical properties are not likely to be significant factors in the hemolytic process.

scholarly journals Geometric, osmotic, and membrane mechanical properties of density- separated human red cells

Blood ◽  
1982 ◽  
Vol 59 (6) ◽  
pp. 1121-1127 ◽  
Author(s):  
O Linderkamp ◽  
HJ Meiselman
Keyword(s):  
Mechanical Properties ◽  
Surface Area ◽  
Time Constant ◽  
Membrane Surface ◽  
Volume Ratio ◽  
Maximal Volume ◽  
Surface Shear ◽  
Area Index ◽  
Actual Volume ◽  
Membrane Mechanical Properties

Abstract Although there is evidence that the deformability of the entire red blood cell (RBC) decreases during aging, reports on changes in relevant specific properties associated with the aging process are limited and not in total agreement. The purpose of this study was to evaluate some of the factors that might contribute to this decreased deformability. Geometric, osmotic, and membrane mechanical properties of unfractionated, top (“young”) and bottom (“old”) RBC from 5 healthy adult donors were measured using micropipette techniques. Surface area, volume, and diameter of RBC were measured at osmolalities of 297, 254, 202, and 153 mosm/kg. Two membrane mechanical properties, surface shear modulus of elasticity (mu) and time constant (tc) of viscoelastic recovery, were studied only in isotonic media. At each of the osmolalities, volume and surface area of the bottom cells were about 25% lower than those of the top cells. Bottom cells showed smaller increases in volume with decreasing osmolality than top cells; the surface area remained constant with changing osmolality for all three groups. The surface area-to-volume ratio and the minimum cylindrical diameter of the bottom cells were essentially identical to the top cells. However, both the surface area index (actual are of RBC divided by area of a sphere of same volume) and the swelling index (maximal volume divided by actual volume) of the bottom cells were significantly lower than top RBC. The shear modules of elasticity (mu) was about 0.006 dyne/cm in all 3 RBC populations, indicating that the forces necessary to deform a portion of the membrane did not change with RBC aging. The viscoelastic time constant (tc) was 0.148 +/- 0.020 (SD) sec for the bottom RBC and 0.099 +/- 0.017 sec for the top cells. This difference indicates that shape recovery following membrane deformation is delayed in old RBC. The membrane surface viscosity (eta), calculated as the product of tc times mu was 0.95 +/- 0.22 x 10(-3) dyne-sec/cm for the bottom cells and 0.54 +/- 0.15 x 10(-3) for the top RBC. These data indicate that the relative deficit in membrane surface area and the increased membrane viscosity of old RBC may be important determinants for their decreased deformability and their eventual removal from the circulation.

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