ISSN:
1432-1017
Keywords:
Erythrocyte
;
cell adhesion, cell agglutination
;
acoustic radiation force
;
ultrasonic levitation
;
interfacial instability
;
polylysine
;
dextran
;
polyethylene glycol
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Physics
Notes:
Abstract A technique which enables cells to be observed in suspension for times of the order of minutes (employing acoustic radiation foreces in a 1 MHz ultrasonic standing wave field) is described. Video recordings of the mutual adhesion of human erythrocytes in suspension have been analysed. Concave-ended cell doublets and linear rouleaux developed in 0.5–1.5% w/v Dextran T500 by a gradual (2.5–17 s) increase in the area of cell contact over the cell cross-section. The concave-ended rouleaux form was not seen in polylysine or in polyethylene glycol. In 5–7% dextran and in 20μg/ml polylysine mutual adhesion was a two stage process. Cells first form a strong local contact which persists (without apparently growing in area) for a number of seconds following which the cell surfaces move suddenly to form a spherical doublet. The average initial contact time and engulfment time for cells in 7% Dextran T500 are 18 and 2.7 s, respectively. The corresponding values for cells in 20 μg/ml, 14 kDa, polylysine are 2.7 and 0.3 s. There was no initial contact delay during spherical doublet formation in mg/ml polylysine. Electron microscopy showed that the intercellular seam for spherical doublets formed with all three agglutinating molecules was bent in a wavy (λ∼4 μm) profile. The thickness of the intercellular space varied in a spatially periodic way (λ∼0.8 μm) for cells in polylysine. Examples of periodic intercellular spaces were seen by light microscopy in polyethylene glycol induced clumps. The role of interfacial instability in the adhesion processes is discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00293260
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