Biorheology - Volume 52, issue 4

Authors: Guardiola, Francisco A. | Cuartero, María | del Mar Collado-González, María | Arizcún, Marta | Díaz Baños, F. Guillermo | Meseguer, José | Cuesta, Alberto | Esteban, María A.

Article Type: Research Article

Abstract: The study of mucosal surfaces, and in particular the fish skin and its secreted mucus, has been of great interest recently among immunologists. Measurement of the viscosity and other physico-chemical parameters (protein concentration, pH, conductivity, redox potential, osmolality and density) of the skin mucus can help to understand its biological functions. We have used five marine species of teleost: gilthead seabream (Sparus aurata L.), European sea bass (Dicentrarchus labrax  L.), shi drum (Umbrina cirrosa L.), common dentex (Dentex dentex L.) and dusky grouper (Epinephelus marginatus L.), all of them with commercial interest in the aquaculture of …the Mediterranean area. Mucus showed a direct shear- and temperature-dependent viscosity, with a non-Newtonian behavior, which differed however between two groups: one with higher viscosity (D. labrax , U. cirrosa , D. dentex ) and the other with lower viscosity (S. aurata , E. marginatus ). In addition, there was a clear interrelation between density and osmolality, as well as between density and temperature. Taking into account that high values of viscosity should improve the barrier effect against pathogens but low values of viscosity are needed for good locomotion characteristics, our results may help elucidate the relationship between physico-chemical and biological parameters of skin mucus, and disease susceptibility. Show more

Keywords: Fish, viscosity, protein concentration, density, osmolality, teleosts, skin mucus

DOI: 10.3233/BIR-15052

Citation: Biorheology, vol. 52, no. 4, pp. 247-256, 2015

Authors: McIntosh, William H. | Ozturk, Mesude | Down, Linden A. | Papavassiliou, Dimitrios V. | O’Rear, Edgar A.

Article Type: Research Article

Abstract: Background: Energy losses at tube or blood vessel orifices depend on the extent of flare as measured by the dimensionless ratio of the fillet radius of curvature to diameter (r / D ). Objective: The goal of this study was to assess the effect of ostial fillet radii on energy losses at the aorta–renal artery junctions since as much as a quarter of cardiac output passes through the kidneys. Method: Pressure loss coefficients K for the renal artery ostia as a function of r / D have been determined for …representative anatomical variants using finite volume simulations. Estimates of fillet radii in humans from image analysis were employed in simulations for comparison of loss coefficients. Results: Values for K drop 45% as r / D increases over the range 0–1.3. Image analysis indicates that the ostia are not symmetric in humans with ( r / D ) superior much larger than ( r / D ) inferior . Simulations show the loss coefficient depends almost entirely on the superior fillet radius. Conclusions: Superior fillet radii for both renal arteries are similar to the optimal value to reduce energy losses while the inferior radii are not. Ostial asymmetry may have been induced by higher levels of shear stress present on the superior portion of a developing symmetric ostium of small r / D . Show more

Keywords: Blood flow, pressure loss coefficient, developmental biology, computational fluid dynamics

DOI: 10.3233/BIR-15069

Citation: Biorheology, vol. 52, no. 4, pp. 257-268, 2015

Authors: Sander, Mathias | Flesch, Julia | Ott, Albrecht

Article Type: Research Article

Abstract: The cell monolayer rheology technique consists of a commercial rotational rheometer that probes the mechanical properties of a monolayer of isolated cells. So far we have described properties of an entire monolayer. In this short communication, we show that we can deduce average single cell properties. Results are in very good agreement with earlier work on single cell mechanics. Our approach provides a mean of 105 –106 adherent cells within a single experiment. This makes the results very reproducible. We extend our work on cell adhesion strength and deduce cell adhesion forces of fibroblast cells on fibronectin coated glass …substrates. Show more

Keywords: Cytoskeleton, oscillatory shear, cell viscoelasticity, cell adhesion, single cell mechanics

DOI: 10.3233/BIR-15070

Citation: Biorheology, vol. 52, no. 4, pp. 269-278, 2015

Authors: Froelich, Jens J. | Ray, Udayan | Monkhorst, Jessica | Marwick, Thomas H. | Hardikar, Ashutosh | Harle, Robin | Carr, Michael W.

Article Type: Research Article

Abstract: Background: Microcatheter directed blood reperfusion is an endovascular salvage option for acute cerebral artery occlusions. It has not been investigated whether this technique may be associated with hemolysis. Objective: Analysis of hemolysis during blood infusion through different microcatheters and infusion rates to assess related risks. Methods: Four microcatheters with different inner diameters were perfused with blood samples at three infusion rates. Hemolytic markers including lactate-dehydrogenase (LDH) and haptoglobin were analyzed. Samples before and after blood infusion were compared using Student’s t -test. Flow-related degree of hemolysis was analyzed with regression analysis. Resulting shear stress was calculated …and correlated with LDH and haptoglobin. Results: Significant increase of LDH and decrease of haptoglobin was found after blood reperfusion through small microcatheters at progressive flow rates (p < 0.05 ). No hemolysis was found with larger diameter microcatheters at all flow rates (p > 0.05 ). Correlation between shear stress, LDH and haptoglobin was r = 0.86 and r = 0.75 , respectively. Conclusions: Progressive hemolysis occurs during blood perfusion of small lumen microcatheters at increasing flow rates. This phenomenon may be related to turbulent flow, exposure time and increased shear stress. Larger microcatheters did not induce hemolysis and may be the preferred choice for stroke reperfusion. Show more

Keywords: Stroke, ischemia, hemolysis, catheterization, blood, reperfusion

DOI: 10.3233/BIR-15074

Citation: Biorheology, vol. 52, no. 4, pp. 279-291, 2015