scholarly journals Cell Surface Area to Volume Relationship During Apoptosis and Apoptotic Body Formation.

2021 ◽  
Vol 55 (S1) ◽  
pp. 161-170
Author(s):  
Francisco J. López-Hernández ◽  
Keyword(s):  
Surface Area ◽  
Membrane Surface ◽  
Volume Ratio ◽  
Total Surface Area ◽  
Point Of View ◽  
Apoptotic Bodies ◽  
Cell Content ◽  
Geometric Point ◽  
Endosomal Membranes ◽  
Cell Corpse

Apoptosis is a programmed form of cell death culminating in packing cell content and corpse dismantling into membrane sealed vesicles called apoptotic bodies (ABs). Apoptotic bodies are engulfed and disposed by neighboring and immune system cells without eliciting a noxious inflammatory response, thus preventing sterile tissue damage. AB formation requires a total surface area larger than the apparent, initial cell's surface area. Apoptotic volume decrease (AVD) is a two-stage process leading to an isotonic, osmotic reduction in cell water content driven by net K+ and Cl- extrusion. In this article, the role of AVD is presented from a geometric point of view through the process of AB formation. AVD decisively contributes to (i) endowing the cell with the appropriate electrolytic environment for apoptotic execution; (ii) increasing the membrane surface area-to-volume ratio, along with the mobilization of membrane reservoirs (cell rounding, membrane folds and endosomal membranes), so that the cell corpse can be dismantled into ABs; and (iii) reducing plasmalemmal stretch, tension and stiffness, thus facilitating membrane bulging, blebbing and vesicle expansion ultimately leading to separation and release.

The ultrastructure of the cardiac Purkinje strand in the dog: a morphometric analysis

1983 ◽  
Vol 217 (1207) ◽  
pp. 191-213 ◽  
Keyword(s):  
Electron Microscopy ◽  
Electrical Properties ◽  
Connective Tissue ◽  
Surface Area ◽  
Series Resistance ◽  
Membrane Surface ◽  
Light And Electron Microscopy ◽  
Total Surface Area ◽  
Membrane Surface Area ◽  
Extracellular Ions

Purkinje strands from both ventricles of adult mongrel dogs were excised, and electrical properties were studied by the voltage-clamp technique. The strands were then examined with light and electron microscopy and structural properties were analysed by morphometric techniques. The canine Purkinje strand contains (by volume) about 28% myocyte and 55% dense outer connective tissue. The remainder of the volume is taken up by the inner shell of loosely packed connective tissue within 10 μm of a myocyte membrane. These volume fractions vary considerably from one strand to another. Clefts less than 10 μm wide occupy 18% of the myocyte volume and clefts less than 1 μm wide occupy 1%. The membrane surface area of the myocytes can be divided into three categories by reference to the size of the adjacent cleft. About 47.8% of the membrane surface area faces clefts wider than 1 μm, another 22.2% faces clefts between 0.1 and 1 μm wide, and the final 30% faces clefts less than 0.1 μm wide. The surface area facing the narrowest clefts (less than 0.1 μm wide) is divided between nexuses 3%, desmosomes 10%, and unspecialized membrane 17% (each figure is expressed as a percentage of the total surface area of myocyte membrane). The canine Purkinje strand has a more favourable anatomy than the sheep Purkinje strand for most physiological experiments. We expect that the complicating effects of series resistance and change in the concentration of extracellular ions will be much smaller than in sheep strands, but still not negligible.

scholarly journals Intrinsic material properties of the erythrocyte membrane indicated by mechanical analysis of deformation

Blood ◽  
1975 ◽  
Vol 45 (1) ◽  
pp. 29-43 ◽  
Author(s):  
EA Evans ◽  
PL La Celle
Keyword(s):  
Surface Area ◽  
Plastic Flow ◽  
Erythrocyte Membrane ◽  
Permanent Deformation ◽  
Volume Ratio ◽  
Total Surface Area ◽  
Water Soluble ◽  
Time Range ◽  
Extrinsic Factors ◽  
Red Cell Membrane

Abstract Deformation of the erythrocyte membrane by the micropipette technique permits analysis of intrinsic material characteristics of the membrane and provides a means to differentiate purely membrane factors from such extrinsic factors as surface area-to-volume ratio. Using small micropipettes (less than 0.5 microns radius) to deform cells, it is evident that the red cell membrane behaves like a solid for periods of time up to 5–10 min of sustained deformation; for long periods of strain, permanent deformations occur, indicative of the semi-solid structural character. In the time range in which the membrane behaves like a solid, the material is linearly elastic up to strains of 400%, implying a loose network structure in the membrane plane, and evaluation of the elastic parameter mu (mu for normal discocytes equals 7 x 10(-3) dynes/cm) suggests that the elements comprising the network may have a molecular weight of approximately that of the water-soluble membrane protein spectrin. Whether the network system is cross-linked or simply a polymer solution remains unanswered. Experimental data indicate that plastic flow of the membrane under conditions of protracted strain may lead to permanent deformation of the membrane, whereas uniform dilation of the membrane, requiring over 1000 times more energy than for plastic flow, results in membrane failure and lysis. Analyses of the data from larger micropipettes of limiting mean cylindrical diameter show their utility in evaluating extrinsic factors, e.g., surface area-to-volume relationships, which are related to the capability of the whole cell to form a new configuration with implicit resistance to total surface area change, as the cell enters narrow channels of the microcirculation. Thus, micropipettes with diameters in the 2.7–3.0-microns range can provide sensitive comparisons of cellular deformability of erythrocytes.

scholarly journals Impact of membrane pore structure on protein detection sensitivity of affinity-based immunoassay

2016 ◽  
Vol 18 (2) ◽  
pp. 97-103 ◽  
Author(s):  
A.L. Ahmad ◽  
N. Ideris ◽  
B.S. Ooi ◽  
S.C. Low ◽  
A. Ismail
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Protein Spot ◽  
Polyvinylidene Fluoride ◽  
Membrane Surface ◽  
Protein Detection ◽  
Protein Immobilization ◽  
Total Surface Area ◽  
Detection Sensitivity ◽  
Membrane Pore

Abstract Understanding a membrane’s morphology is important for controlling its final performance during protein immobilization. Porous, symmetric membranes were prepared from a polyvinylidene fluoride/N-methyl-2-pyrrolidinone solution by phase inversion process, to obtain membrane with various microsized pores. The concentration and surface area of aprotein dotted on the membrane surface were measured by staining with Ponceau S dye. The dotted protein was further scanned and analysed to perform quantitative measurements for relative comparison. The intensity of the red protein spot and its surface area varied depending on the membrane pore size, demonstrating the dependence of protein immobilization on this factor. The membrane with the smallest pore size (M3) showed the highest protein spot intensity and surface area when examined at different protein concentrations. An increase in the applied protein volume showed a linearity proportional trend to the total surface area, and an uneven round dot shape was observed at a large applied volume of protein solution.

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.

A stereological comparison of villous and microvillous surfaces in small intestines of frugivorous and entomophagous bats: species, inter-individual and craniocaudal differences.

1997 ◽  
Vol 200 (18) ◽  
pp. 2415-2423 ◽  
Author(s):  
A N Makanya ◽  
J N Maina ◽  
T M Mayhew ◽  
S A Tschanz ◽  
P H Burri
Keyword(s):  
Surface Area ◽  
Body Mass ◽  
Membrane Surface ◽  
Total Surface Area ◽  
Membrane Surface Area ◽  
Intestinal Tube ◽  
Surface Areas ◽  
Intestinal Length ◽  
Mass Coefficient ◽  
Extensive Surface

The extents of functional surfaces (villi, microvilli) have been estimated at different longitudinal sites, and in the entire small intestine, for three species of bats belonging to two feeding groups: insect- and fruit-eaters. In all species, surface areas and other structural quantities tended to be greatest at more cranial sites and to decline caudally. The entomophagous bat (Miniopterus inflatus) had a mean body mass (coefficient of variation) of 8.9 g (5%) and a mean intestinal length of 20 cm (6%). The surface area of the basic intestinal tube (primary mucosa) was 9.1 cm2 (10%) but this was amplified to 48 cm2 (13%) by villi and to 0.13 m2 (20%) by microvilli. The total number of microvilli per intestine was 4 x 10(11) (20%). The average microvillus had a diameter of 8 nm (10%), a length of 1.1 microns (22%) and a membrane surface area of 0.32 micron 2 (31%). In two species of fruit bats (Epomophorus wahlbergi and Lisonycteris angolensis), body masses were greater and intestines longer, the values being 76.0 g (18%) and 76.9 g (4%), and 73 cm (16%) and 72 cm (7%), respectively. Surface areas were also greater, amounting to 76 cm2 (26%) and 45 cm2 (8%) for the primary mucosa, 547 cm2 (29%) and 314 cm2 (16%) for villi and 2.7 m2 (23%) and 1.5 m2 (18%) for microvilli. An increase in the number of microvilli, 33 x 10(11) (19%) and 15 x 10(11) (24%) per intestine, contributed to the more extensive surface area but there were concomitant changes in the dimensions of microvilli. Mean diameters were 94 nm (8%) and 111 nm (4%), and mean lengths were 2.8 microns (12%) and 2.9 microns (10%), respectively. Thus, an increase in the surface area of the average microvillus to 0.83 micron 2 (12%) and 1.02 microns 2 (11%) also contributed to the greater total surface area of microvilli. The lifestyle-related differences in total microvillous surface areas persisted when structural quantities were normalised for the differences in body masses. The values for total microvillous surface area were 148 cm2g-1 (20%) in the entomophagous bat, 355 cm2g-1 (20%) in E. wahlbergi and 192 cm2g-1 (17%) in L. angolensis. This was true despite the fact that the insecteater possessed a greater length of intestine per unit of body mass: 22 mm g-1 (8%) versus 9-10 mm g-1 (9-10%) for the fruit-eaters.

scholarly journals Intrinsic material properties of the erythrocyte membrane indicated by mechanical analysis of deformation

Blood ◽  
1975 ◽  
Vol 45 (1) ◽  
pp. 29-43 ◽  
Author(s):  
EA Evans ◽  
PL La Celle
Keyword(s):  
Surface Area ◽  
Plastic Flow ◽  
Erythrocyte Membrane ◽  
Permanent Deformation ◽  
Volume Ratio ◽  
Total Surface Area ◽  
Water Soluble ◽  
Time Range ◽  
Extrinsic Factors ◽  
Red Cell Membrane

Deformation of the erythrocyte membrane by the micropipette technique permits analysis of intrinsic material characteristics of the membrane and provides a means to differentiate purely membrane factors from such extrinsic factors as surface area-to-volume ratio. Using small micropipettes (less than 0.5 microns radius) to deform cells, it is evident that the red cell membrane behaves like a solid for periods of time up to 5–10 min of sustained deformation; for long periods of strain, permanent deformations occur, indicative of the semi-solid structural character. In the time range in which the membrane behaves like a solid, the material is linearly elastic up to strains of 400%, implying a loose network structure in the membrane plane, and evaluation of the elastic parameter mu (mu for normal discocytes equals 7 x 10(-3) dynes/cm) suggests that the elements comprising the network may have a molecular weight of approximately that of the water-soluble membrane protein spectrin. Whether the network system is cross-linked or simply a polymer solution remains unanswered. Experimental data indicate that plastic flow of the membrane under conditions of protracted strain may lead to permanent deformation of the membrane, whereas uniform dilation of the membrane, requiring over 1000 times more energy than for plastic flow, results in membrane failure and lysis. Analyses of the data from larger micropipettes of limiting mean cylindrical diameter show their utility in evaluating extrinsic factors, e.g., surface area-to-volume relationships, which are related to the capability of the whole cell to form a new configuration with implicit resistance to total surface area change, as the cell enters narrow channels of the microcirculation. Thus, micropipettes with diameters in the 2.7–3.0-microns range can provide sensitive comparisons of cellular deformability of erythrocytes.

scholarly journals The Biconcavity of the Red Cell: An Analysis of Several Hypotheses

Blood ◽  
1973 ◽  
Vol 41 (6) ◽  
pp. 833-844 ◽  
Author(s):  
Brian S. Bull ◽  
J. Douglas Brailsford
Keyword(s):  
Mechanical Properties ◽  
Surface Area ◽  
Long Range ◽  
Protein Interaction ◽  
Membrane Surface ◽  
Total Surface Area ◽  
Support Surface ◽  
Red Cell ◽  
Surface Shear ◽  
New Evidence

Abstract New evidence is presented to show that the dimple and the annulus of the red cell are not restricted to specific locations on the membrane. This eliminates all but one of the current theories of biconcavity and supports the view that the membrane has unusual mechanical properties such that, although it cannot support surface shear, it can resist both bending and increase in total surface area. The feasibility of such a material is demonstrated by means of a macromodel. The model represents a class of structure that until recently has received little attention but that strongly suggests long-range protein interaction in the membrane surface.

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

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.

The Functional Dependence of Leaching on The Surface Area-To-Solution Volume Ratio

1982 ◽  
Vol 15 ◽  
Author(s):  
Albert J. Machiels ◽  
Claudio Pescatore
Keyword(s):  
Surface Area ◽  
Functional Dependence ◽  
Mathematical Formulation ◽  
Volume Ratio ◽  
Computer Code ◽  
Point Of View ◽  
Theoretical Point ◽  
Leaching Experiments ◽  
Glass Leaching ◽  
Solution Volume

ABSTRACTThe effects of the surface area-to-solution volume ratio on waste glass leach rates are investigated from a theoretical point of view. Simple leach models are discussed first. Correlation variables to interpret the results of similar leaching experiments performed at different values of the surface area-to-solution volume ratio are obtained for static leach testing. For dynamic leaching conditions, the source term required for risk assessment is derived and its dependence on the leachant flow rate and leach specimen surface area is discussed. The findings are upheld by a more complex leach model, the mathematical formulation of which has been implemented in a computer code named LIX. When tested against actual PNL 76–68 glass leaching data, LIX shows excellent capabilities in reproducing the experimental evidence, in particular the effects of the surface area-to-solution volume ratio.

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