The measurement of shear modulus and membrane surface viscosity of RBC membrane with Ektacytometry: a new technique.

A new technique is proposed to estimate the shear modulus (mu) and membrane surface viscosity (eta(m)) of red blood cell (RBC). Theoretical formulae for finding these two parameters are first derived based on the force balance on a RBC in a flow field of low viscosity. Different types of Ektacytometry are then used to measure relevant quantities. The obtained values (mu=6.1 x 10(-6)N/m, eta(m)=8.8 x10 (-7)Ns/m for normal RBC) are consistent with those previously found by micropipette technique and in AC electric field. The present technique is, however, much easier to operate and more advantageous in reflecting the average properties of a large quantity of RBCs, and it is much cheaper to be applied in clinical practice than any other method of measuring the two parameters. The sensitivity of the technique is demonstrated by testing RBCs treated with glutaraldehyde of different concentrations. This technique was demonstrated by the flow chamber.

[Progress in the research on hemodynamics of portal hypertension].

Portal hypertension (PHT), as a disease with high incidence all over the world, badly affects the patients' health. The research on hemodynamics plays an important role in exploring the pathogenesis of PHT, assessing the risk of hemorrhage induced by the complications, selecting the scheme and time of surgical operations as well as evaluating the curative effects of medication. In this article, the main factors in the pathogeny of PHT are reviewed and the surgical treatments are discussed from the hemodynamic viewpoint. Then some recent results in the hemodynamic research of PHT are summarized. In addition, main ideas are put forward as to establishing a new global biomechanical model of PHT.

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 K (1) which is inversely proportional to cells' maximal deformation ability, obviously diminished surface viscosity mu, with elastic modulus K (2)having no distinct changes. The above results provided some bases for recognizing the function of TFAR19 completely from the viewpoint of biorheology.

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 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.