On the flocculation of sheep leucocytes: II. Stability studies

Wilkins, D. J.; Ottewill, R. H.; Bangham, A. D.

doi:10.1016/0022-5193(62)90046-2

Cited by 58 publications

(11 citation statements)

References 20 publications

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“…In flocculation experiments a mean value of 1.6 + 1.0 x 10-14 ergs was found for A (Wilkins, Ottewill & Bangham, 1962). The relatively low value of 0.5 x 10-14 which was suggested by Weiss (1968) from an analysis of cell detachment experiments, falls within the range of our values for A.…”

Section: Resultssupporting

confidence: 82%

Van der waals interactions between cell surfaces

Nir

Andersen

1977

J. Membrain Biol.

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Van der Waals energies of interaction between model cell surfaces are calculated for various distances of separation, layer thicknesses and compositions of cell surfaces and intercellular media. In these calculations the cell peripheries are considered to consist of two layers: (1) A phospholipid-cholesterol-protein plasma membrane and (2) a surface coat, which consists of protein, sugar and water. The required Van der Waals parameters of sugars, phospholipids and cholesterol are derived from refractive indices of their solutions in the visible and ultraviolet regions. Polarizabilities and Van der Waals parameters of these substances are determined and shown to be almost independent of concentration of solutions. Resulting isotropic polarizabilities differ by less than five percent from values obtained by the addition of bond polarizabilities. The magnitude of Van der Walls interactions between cell surfaces has been found to vary with composition according to the following sequence: water less than phospholipid less than cholesterol, protein less than sugar. A decrease in the concentration of a given substance in the cell surface at the expense of a corresponding increase in the concentration of a substance preceding it in this sequence lowers the magnitude of attractive interactions, whereas a similar change in the extracellular medium would have an opposite effect. A consideration of experimentally found variations in composition of cell surfaces results in calculated values of Hamaker's coefficients between 8 X 10(-15) ergs and 6 X 10(-14) ergs at 50 A distance of separation, which corresponds to free energies per unit area of 210-1600 kT/mu2.

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Section: Resultssupporting

confidence: 82%

Van der waals interactions between cell surfaces

Nir

Andersen

1977

J. Membrain Biol.

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“…In contrast to the ascites tumor cells, the RPMI No. 41 cells show evidence (Table II and The technique of quantitating cell adhesion by agglutination experiments has been used by Armstrong (13) and Wilkins et al (14,15) among others; and experiments made with agglutinating antisera show it to be a sensitive test of cell adhesion as used in the present study. It should be noted that, in other studies on agglutination with No.…”

Section: Cell Aggregationmentioning

confidence: 62%

“…Thus, addition of calcium ions will produce a reduction in VR (through 1/K). This aspect of DLVO thoery is applicable in general terms to the adsorption of virus particles (25) and agglutination of leukocytes (14,15). The theory was also invoked to account for some observations (26) in which it was shown that the percentage of cells shaken off glass surfaces to which they were attached, was sensitive to the calcium concentrations in their culture media.…”

Section: Cell Aggregationmentioning

confidence: 99%

Studies of Cell Deformability

Weiss

1967

The Journal of Cell Biology

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Cells grown in suspension culture were incubated with EDTA-disodium salt and shown to have more easily deformable surfaces and raised electrophoretic mobility than controls, following this treatment. The reversibility of these observations by the addition of calcium ions, and other parallel experiments, support the conclusion that, in these cells, calcium is bound to anionic sites at the cell periphery, some of which are located at the cellular electrokinetic surface. These cells should, therefore, exhibit demonstrable calcium-sensitive aggregation, if current theories on the role of calcium in the physiological situation are correct. The fact that no calcium-sensitive aggregation was observed suggests that calcium does not form "bridges" between the adjacent anionic sites on different cells, and does not act directly by its effects on the diffuse electrical double-layer in this situation. An alternative hypothesis is advanced for the role played by calcium in cell adhesion and separation processes.In the previous paper of this series, some effects of incubating murine ascites sarcoma 37 cells with EDTA were described, and a model for calciumbinding within their peripheral zones, in the presence of physiological quantities of calcium ions, was tentatively suggested (1). In the present communication, further experiments on EDTAtreatment of other cells are described which enable another model to be advanced which relates to calcium in the cell periphery, to cell adhesion, and cell separation. The two models are complementary rather than mutually exclusive, and will be discussed in general biological context. MATERIAL AND METHODSThroughout the experiments, use was made of RPMI No. 41 cells which were derived from a human osteogenic sarcoma (2), and which have been maintained in suspension culture at 37°C in synthetic medium RPMI 906 (3) plus 5% calf serum. The withdrawn samples contained between 2.5 X 105 and 5.0 X 105 cells per ml, of which at least 94% were viable as judged by their ability to exclude trypan blue.Cells removed from the culture vessels were washed in either Hanks' balanced salt solution (HBSS) which contains 0.0013 M CaC1 2 and 0.002 M MgCI 2 in addition to univalent ions, or calcium-magnesiumfree HBSS (CMF), and then incubated in either 0.5% (0.013 M) disodium EDTA (EDTA) dissolved in CMF and having a final pH of 5.7, or control solutions, at 37°C for 30 min. Following incubation, the cells were washed twice in either CMF or HBSS at pH 7.0-7.3.For the purpose of testing the specificity of EDTA for calcium and magnesium in its effect on cell deformability, cells were also incubated for 30 min at 37°C in 0 5% magnesium disodium ethylenediamine tetraacetate (MgNa2EDTA) in CMF, and in a 0.5% solution of the calcium disodium salt of EDTA (CaNa2EDTA) in CMF. In some experiments, an attempt was made to restore the original properties to EDTA-treated cells by reincubating them for 30 min at 37°C in HBSS, CMF + Mg + + containing 0.002 347 on

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“…This with the later introduction of the theories of colloid stability by Derjaguin and Landau [5] and Verwey and Overbeck [6] linked the stickiness of particles to ideas of colloid stability. This was examined in the context of phagocytosis by Wilkins et al [7,8]. The work of Good and Girifalco [9] and Fowkes [10] then linked the Hamaker Constant to the dispersion contribution to surface tension.…”

Section: Introductionmentioning

confidence: 99%

Surface Tension, Stickiness and Engulfment

Ottewill

Schofield

Waters

1998

Journal of Dispersion Science and Technology

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The thermodynamic conditions for the engulfment of one set of particles by another has been given in terms of interfacial energies. Experimentally, it has been shown that a polymer with a high glass transition temperature can be engulfed by a particle of low glass transition temperature; also, that inorganic particles can be engulfed by polymer particles. As a precursor to then engulfment stage heterocoagulation can be used for bringing the particles together in a "sticking" mode. This appears to be a general process which is applicable to a number of scientific areas, e.g. in biology, phagocytosis, and in material science for the preparation of composite particles.

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On the flocculation of sheep leucocytes: II. Stability studies

Cited by 58 publications

References 20 publications

Van der waals interactions between cell surfaces

Van der waals interactions between cell surfaces

Studies of Cell Deformability

Surface Tension, Stickiness and Engulfment

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