Zongyi Yan

Low viscosity Ektacytometry and its validation tested by flow chamber

The flow chamber was used to observe the orientation and small deformation of red blood cells (RBCs) in a shear flow of low viscosity. With the aid of computer software, the percentage of RBCs oriented to the C=0 orbit (OI)(F) and the degree of deformation (DI)(F) of such RBCs were calculated by processing the photographs. It was found that these parameters were highly correlated, respectively, to the orientation index (OI)(E) and the small deformation index (DI)(E) obtained by our low viscosity Ektacytometry (LVE). Thus, our flow chamber research has provided direct evidence to validate the use of this low viscosity Ektacytometry. Although there are relative merits for the flow chamber method using low viscosity medium, the LVE is more likely to be applied in clinic for its simplicity and convenience.

Influence of TRAIL gene on biomechanical properties of the human leukemic cell line Jurkat

We cloned the cDNA fragment of human TNF-related apoptosis inducing ligand (TRAIL) into RevTet-On, a Tet-regulated and high-level gene expression system. Making use of the TRAIL gene expression system in Jurkat as a cell model, we studied the influence of TRAIL gene on the biomechanics properties of Jurkat through measuring changes of cellular biomechanics properties before and after the TRAIL gene expression, which was induced by adding tetracycline derivative doxycycline (Dox). The results indicated that the TRAIL gene expression led to significant changes in cellular biomechanics properties. The osmotic fragility increased and the cell stiffness increased after the expression of TRAIL gene. Thus, the apoptosis-inducing TRAIL gene caused significant changes in the biomechanics properties of Jurkat cells.

BIOPHYSICAL MEANINGS OF ORIENTATION AND DEFORMATION OF RBCS IN SHEAR FLOW FIELD OF LOW VISCOSITY WITH NEW EKTACYTOMETRY

The rheological behavior of RBCs treated with WGA of different concentrations was measured by the recently developed new Ektacytometry method in suspending medium of low viscosity. The biophysical meanings of the orientation index (DI)or and the small deformation index (DI)d in the new Ektacytometry were explained by comparison with the results using the fluorescence polarization technique and the electron spin resonance technique (ESR).

Effects of TFAR19 gene on the growth and biorheological properties of mouse erythroleukemia cell line MEL.

Using the method of gene transfection with liposome, we obtained the mouse erythroleukemia cell line MEL-TF19, which stably carries TFAR19, a novel apoptosis-related gene. The expression of TFAR19 was detected by Western blot. Growth curve and flow cytometry analysis showed that after being transfected with TFAR19 gene, the growth of MEL-TF19 is suppressed and its apoptosis is accelerated because of the serum deprivation. Our biorheological study indicated that in the apoptotic process, compared with MEL cells, MEL-TF19 cells exhibit larger osmotic fragility, lower cell surface charge density, increased elastic modulus K1 which is inversely proportional to cells’ maximal deformation ability, obviously diminished surface viscosity μ, with elastic modulus K2having no distinct changes. The above results provided some bases for recognizing the function of TFAR19 completely from the viewpoint of biorheology.

Biophysical and biorheological studies on the precursor cells at different stages

Splenic erythroblasts were obtained from mice during the acute disease caused by anemiainducing virus (FVA). They were cultured in a medium containing EPO, BSA and so on. We studied their biomechanical and hemorheological behavior after 12 h, 24 h and 48 h. The results showed obvious changes in their electrophoretic mobility, osmotic fragility, membrane fluidity and membrane viscoelastic properties with the development of erythroblast. The changes were associated with the interactions of the protein and lipid and the elements of the membrane.