Studies on intercellular adhesion

Jones, Gareth E (1972) Studies on intercellular adhesion. PhD thesis, University of Glasgow.

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Dielectric constant measurements were made, in the frequency range 100 kHz to 1 MHz, on the compounds glycine, diglycine, D-sorbitol, dextran 15-20,000) and. Ficoll (m.w t. 400,000) in aqueous solutions of low specific conductivity (<200 x 10-4 ohm-1 m-1) normally buffered to pH 7.45. The values obtained were used to predict the dielectric constant of Hanks-199 tissue culture medium, to which various concentrations of these compounds had been added. Single-cell dispersions of two primary chick embryonic tissues, 7-day neural retina and 5-day limb bud, were prepared in tissue culture media of varying dielectric constant and also in suitable controls. Ionic strength, pH and. osmolarity were kept equal in experimental and control media. Selected cell dispersions were examined by means of particle electrophoresis in order to determine their electrokinetic potentials. It was found that 7-day neural retina tissue had a mean value for the zeta potential of -13.88 mV +/- 0.04 S.E. in unmodified medium, this value falling slightly in the media of differing composition. The 5-day limb bud tissue gave a value for the zeta potential of -14.37 mV +/- 0.03 S.E. in normal medium, again showing a slight falling off in the modified media. The results were interpreted as showing that no significant adsorption of added compounds was occurring onto the cell membranes, thus changing their surface properties. Cell suspensions in media of a range of dielectric constant were subjected to a laminar flow shear gradient in a Couette viscometer. The effect of this shear gradient was to bring about collisions between the cells and thus to effect aggregation of these suspensions. By measuring the total number of particles in the suspension at timed intervals a parameter was calculated for each aggregation, the collision efficiency. The collision efficiency is a measure of the rate of aggregation and also can be used to calculate the total energy of adhesive interaction of the cells. The collision efficiency was used to calculate this parameter from aggregation studies in media of varying dielectric constant. It was shown firstly that 5-day limb bud tissue gave much lower values for this parameter (termed the force constant) than did 7-day neural retina. In the control media, the former gave a value of 3.66 x 10-26 J. and the latter 5.65 x 10-23 J. Secondly it was discovered that in both tissues there was a steady increase in the adhesive interaction of the cells (as measured by the force constant) with increasing dielectric constant of the aggregation medium, the 5-day limb bud being far more sensitive than 7-day neural retina in this respect. These observations were discussed in relation to the lyophobic colloid stability theory of cell adhesion. The results were found to be consistent with this theory when account was taken of recent theoretical studies into the effect of the dielectric properties of a medium on the attractive energy of particles suspended in that medium.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: A SG Curtis
Keywords: Cellular biology
Date of Award: 1972
Depositing User: Enlighten Team
Unique ID: glathesis:1972-73875
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56

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