Biorheology - Volume 40, issue 1-3

Authors: Elo, Mika A. | Sironen, Reijo K. | Karjalainen, Hannu M. | Kaarniranta, Kai | Helminen, Heikki J. | Lammi, Mikko J.

Article Type: Research Article

Abstract: In chondrocytes, a low‐amplitude intermittent hydrostatic pressure induces production of extracellular matrix molecules, while high hydrostatic pressure inhibits it. High pressure increases cellular heat shock protein 70 level in a number of cell types on account of increased stabilisation of the heat shock protein 70 mRNA. In our experiments, only bovine primary chondrocytes, but not an immortalized chondrocytic cell line, could resist the induction of the stress response in the presence of continuous 30 MPa hydrostatic pressure. We have recently shown that protein synthesis is required for the stabilization. According to two‐dimensional gel electrophoresis the synthesis of heat shock protein …90 was also increased in a chondrocytic cell line and in HeLa cells, and mass spectrometric analysis suggested that the induction was rather due to increase in heat shock protein 90β than in heat shock protein 90α. The stress response was rather intense in HeLa cells, therefore, we investigated the effect of continuous 30 MPa hydrostatic pressure on the expression of the two heat shock protein 90 genes in HeLa cells using Northern and Western blot analyses. Heat shock protein 90β mRNA level increased within 6 hours of exposure to 30 MPa hydrostatic pressure, while hsp90α level remained stable. At protein level there was a clear increase in the heat shock protein 90β/heat shock protein 90α ratio, too. These results show a specific regulation of stress proteins in cells exposed to high hydrostatic pressure. Show more

Citation: Biorheology, vol. 40, no. 1-3, pp. 141-146, 2003

Authors: Hemmerlé, J. | Picart, C. | Gergely, C. | Schaaf, P. | Stoltz, J.‐F. | Voegel, J.‐C. | Senger, B.

Article Type: Research Article

Abstract: This article deals with the modeling of the detachment of a molecule initially adsorbed on a surface and submitted to an external force whose strength increases with time. By means of an atomic force microscope (AFM), it is possible to measure the force when the molecule separates from the substrate. However, it is known that this force depends to a large extend on the rate at which the pulling force is applied (“Bell–Evans effect”). Two models are described to illustrate this behavior. First, a random walk approach is suggested to reveal the fundamental principle of the escape over a time‐dependent …energy barrier. Second, a multi bead‐and‐spring model is proposed to mimic the AFM experiment and numerical simulations, based on Brownian dynamics, are performed. Show more

Citation: Biorheology, vol. 40, no. 1-3, pp. 149-160, 2003

Authors: Riha, P. | Dumas, D. | Latger, V. | Muller, S. | Stoltz, J.F.

Article Type: Research Article

Abstract: The role of clustered of L‐selectin receptors on the leukocyte surface is discussed in connection with the postulated velocity‐dependent formation of selectin–ligand tether bonds to interpret the mechanism of leukocyte tethering to, and rolling along, the vascular endothelium. The distinct feature of this step‐wise process is a weak dependence of leukocyte rolling velocity on the hydrodynamic forces of ambient flow due to the increased number of selectin bonds with increasing flow shear rate and also their clustering. The contact zones on the leukocyte surface are separated by distances with distribution which corresponds to the distribution of distances of the observed …L‐selectin clusters. It suggests that the localization of L‐selectin receptors to clusters and the way of their approach to the ligand molecules creates such conditions for binding of L‐selectin and ligand molecules that resulting number of bonds stabilizes rolling velocity. Show more

Citation: Biorheology, vol. 40, no. 1-3, pp. 161-166, 2003

Authors: Latger‐Cannard, Véronique | Dumas, Dominique | Bensoussan, Danièle | Stoltz, Jean‐François

Article Type: Research Article

Abstract: Receptors such as CD62L and CD11b/CD18, are transmembrane glycoproteins which regulate leukocyte adhesive phenotype. Flow cytometry (FCM) makes it possible to assess a characterization of the cell activation level by receptor quantifying, but that technique does not integrate other factors of adherence regulation, such as spatial distribution and molecular conformation. Our study consisted in exploring the main adherence receptors on Polymorphonuclear Neutrophils (PMN) that were simultaneously analyzed by FCM and Conventional Optical Scanning Microscopy (COSM). FCM analysis showed that TNFα induce a decrease in CD62L expression and an increase in β2 integrins. COSM analysis distinguished three stages of cellular …distribution of CD11b/CD18 within resting PMN: most of them (about 80%) had homogeneous distribution (heterogeneous spots distributed over the entire cell surface), for 10–15% of the cells, there was a crown distribution around the widest cell diameter and in less that 10% of them receptor distribution was polarized. CD62L was in the form of heterogeneous spots distributed in a circle on the surface on non‐stimulated PMN. PMN stimulation by TNFα was associated to a randomized clustering involving both selectin and β2 integrin. Three‐dimensional analysis elicited data not shown by quantitative cytometry. For a single averaged value of the density determined by FMC, various spatial distributions of adherence receptors are found on the surface of non‐stimulated PMN. The characterization of the leukocyte adhesive phenotype has to integrate adherence receptors density as well as their spatial distribution. Show more

Keywords: 3D microscopy, polymorphonuclear neutrophil, adherence receptors

Citation: Biorheology, vol. 40, no. 1-3, pp. 167-172, 2003

Authors: Renard, M. | Heutte, F. | Boutherin‐Falson, O. | Finet, M. | Boisseau, M.R.

Article Type: Research Article

Abstract: Background: Rolling of leukocytes at the surface of the vascular endothelium is a prerequisite for a subsequent firm adhesion, particularly the slow rolling appearing on ELAM CD62E. Therefore, it may be considered that increasing the rolling velocities should be a precise therapeutic target in clinical situations where leukocytes accumulate, mainly venous and arterial ischaemia. Methods: Human neutrophils were allowed to flow on endothelial HUVECs, with and without 4 hours interleukin‐1α activation, the cells having or not been incubated with INO5042 anti‐inflammatory drug. Under a mean shear‐stress of 2 dyn/cm2 , rollers and stickers were identified and quantified, using a …video‐camera and picture analysing software. Results: When the drug had been added to endothelial cells a shift of velocities was observed towards fast speeds (from 3–5 to 7–11 μm/sec). The same results was significantly found when neutrophils, alone or along with endothelium, had been submitted to the drug, the number of stickers and rollers beeing reduced as well. Finally, such a precise pharmacological method proved efficient to detect the exact mechanism of INO5042 on white cell adhesion. Show more

Citation: Biorheology, vol. 40, no. 1-3, pp. 173-178, 2003

Authors: Zhao, Hong | Zhuang, Fengyuan | Stoltz, Jean François | Wang, Xiong

Article Type: Research Article

Abstract: Interaction of lymphocyte function‐associated antigen‐1 (LFA‐1) with intercellular adhesive molecule‐1 (ICAM‐1) is important in a number of cellular events, including inflammation, adhesion, transendothelial migration. The aim of this work was to study comparatively the adhesive interaction between LFA‐1 and ICAM‐1 by a micropipette technique and a flow chamber method, and also to explore the effects of tumor necrosis factor (TNF‐α), phytohemagglutinin (PHA), and tetramethylpyrazine (TMP) on this interaction. The adhesion probability (Pa) between a lymphocyte cell line SKW‐3 expressing LFA‐1 and a red blood cell (RBC) coated with soluble ICAM‐1 was approached by the micropipette technique, while the flow chamber …allowed to observe the firm adhesion of SKW‐3 on human umbilical vein endothelial cells (HUVECs). Experimental results show that PHA stimulation of lymphocytes resulted in significant increases in the adhesion probability (Pa) and in number of firmly adhered lymphocytes to HUVECs, but TMP treatment could significantly inhibit such increases. Show more

Keywords: Cell adhesion, LFA‐1, ICAM‐1, micropipette, flow chamber

Citation: Biorheology, vol. 40, no. 1-3, pp. 179-187, 2003

Authors: Gigant, C. | Latger‐Cannard, V. | Bensoussan, D. | Fawzi, S. | Feugier, P. | Bordigoni, P. | Stoltz, J.F.

Article Type: Research Article

Abstract: To investigate the function of the main adhesion receptors (CD62L, CD49d, CD49e, CD11b and CD18) on CD34+ cells during homing, their expression was quantified by flow cytometry using calibration beads. CD34+ cells were isolated from bone‐marrow (BM), cord blood (CB) or peripheral blood (PB) from patients with myeloma. As this process might mimic the mature leukocyte migration, we also observed the effect of exposing endothelial cells to shear stress (7 dyn/cm2 ) on the adhesion of CB CD34+ cells. The proportion of CD34+/CD62L+ cells was greater in PB than in BM (p<0.05). Likewise, we found a significantly greater expression …of CD62L receptor on PB cells compared to BM cells (p<0.05) and on BM cells compared to CB cells (p<0.05). The proportions of CD34+/CD49d+ cells and CD34+/CD49e+ cells were significantly higher in the BM and CB than in PB. However, no significant difference in CD49d or CD49e antigen densities was observed. The β2 integrins (CD11b and CD18) receptors are also implicated in CD34+ cells homing to BM. No significant variation in CD34+/CD11b+ and CD34+/CD18+ cells frequency was noted. However quantitative analysis revealed that CD18 was more strongly expressed on BM cells than on PB and CB cells. The adhesion assay showed that fluid flow may favour a firm adhesion of CB CD34+ cells to endothelial cells whereas static conditions just allowed CD34+ cells sedimentation. In conclusion, quantitative expression of the main receptors on CD34+ cells indicates that the three main sources of CD34+ cells currently used for transplantation have neither the same phenotype nor the same number of antigenic sites for a receptor. So, we hypothesize that migrational capacity of these cells might be different. Moreover, it seems that shear stress could favor adhesion of CD34+ cells to endothelial cells. Show more

Keywords: Adhesion molecules, CD34+ cells, endothelial cells, hematopoietic stem cell transplantation, quantitative expression, shear flow

Citation: Biorheology, vol. 40, no. 1-3, pp. 189-195, 2003

Authors: Rasia, R.J. | de Isla, N. | Altube, L. | Muller, S. | Valverde, J. | Stoltz, J.F.

Article Type: Research Article

Abstract: A problem in immunohematology is to define the antibody quality which is related to its affinity expressed by the equilibrium constant. The activity of an antibody can be measured by the strength of its interaction, related to the adhesive energy exchanged during RBC agglutination which depends on the antigen–antibody liaison strength. To estimate this adhesive energy, two methods are used in this paper. Firstly, the dissociation behaviour of suspended RBC agglutinates was analysed by laser backscattering intensity (r) in a Couette flow. Backscattered intensity issued from shear‐induced mechanical dissociation is recorded and submitted to a numerical process to obtain the …energy parameter (ED ). Secondly, a modification of this technique is proposed for measuring specific binding energy. Samples were exposed to increasing shear stress, and backscattered intensity was recorded. A constant increase of this intensity with raising shear stress was observed, pointed to a progressive dissociation of RBC agglutinates into smaller ones. Considering that complete dissociation of agglutinates is only approached asymptotically it is assumed that the final break‐up of doublets (two‐cell agglutinates) is produced at a critical shear stress (τC ) reflecting the work done to breaking‐up the molecular bridges between both adjacent cells. This shear stress is defined by the extrapolation of the linear part of the curves [r–log τ] to the backscattered signal (r0 ) corresponding to the complete dispersion of RBCs. These approaches permit to define the specific surface adhesive energy (Γ) by using the Derjaguin relation and to assess the functional characterization of specific immunoglobulins. In conclusion, two parameters characterizing monoclonal antibody agglutination properties, ED and Γ, were estimated by laser backscattering methods, which could be very useful for antibodies quality control. Show more

Keywords: Blood group antigens, monoclonal antibodies, rheooptical method, laser backscattering

Citation: Biorheology, vol. 40, no. 1-3, pp. 197-203, 2003

Authors: Miyazaki, Hiroshi | Hayashi, Kozaburo | Hasegawa, Yoshitaka

Article Type: Research Article

Abstract: Tensile properties of fibroblasts (FBs) and vascular smooth muscle cells (VSMCs) of synthetic and contractile phenotypes were studied using a newly developed micro‐tensile tester. FBs were obtained from the rabbit patellar tendon. Synthetic and contractile VSMCs were isolated from the rabbit thoracic aorta with an explant and an enzymatic digestion method, respectively. Each cell was attached to the fine tips of a pair of micropipettes with a cell adhesive and, then, stretched at the speed of 6 μm/sec. Load and length were obtained using a cantilever‐type load cell and a VDA, respectively. FBs were broken at the load of …0.9 μN and the elongation to failure of 86 μm, and had the stiffness of 0.02 N/m. VSMCs were not broken even at 2.4 μN. The stiffness of synthetic and contractile VSMCs were 0.09 and 0.17 N/m, respectively. Such large different tensile properties among the three cells are attributable to the differences in components and cytoskeletal structures. Show more

Citation: Biorheology, vol. 40, no. 1-3, pp. 207-212, 2003

Authors: Volokh, K.Yu.

Article Type: Research Article

Abstract: Conventional continuum mechanics models considering living cells as viscous fluid balloons are unable to explain some recent experimental observations. In contrast, new microstructural models provide the desirable explanations. These models emphasize the role of the cell cytoskeleton built of struts‐microtubules and cables‐microfilaments. A specific architectural model of the cytoskeletal framework called “tensegrity” deserved wide attention recently. Tensegrity models particularly account for the phenomenon of linear stiffening of living cells. These models are discussed from the structural mechanics perspective. Classification of structural assemblies is given and the meaning of “tensegrity” is pinpointed. Possible sources of non‐linearity leading to cell stiffening are …emphasized. The role of local buckling of microtubules and overall stability of the cytoskeleton is stressed. Computational studies play a central role in the development of the microstructural theoretical framework allowing for the prediction of the cell behavior from “first principles”. Algorithms of computer analysis of the cytoskeleton that consider unilateral response of microfilaments and deep postbuckling of microtubules are addressed. Show more

Citation: Biorheology, vol. 40, no. 1-3, pp. 213-220, 2003