Biorheology - Volume 49, issue 5-6

Authors: Sugihara-Seki, Masako | Akinaga, Takeshi | O-Tani, Hideyuki

Article Type: Research Article

Abstract: A fluid mechanical and electrostatic model for the transport of solute molecules across the vascular endothelial surface glycocalyx layer (EGL) was developed to study the charge effect on the diffusive and convective transport of the solutes. The solute was assumed to be a spherical particle with a constant surface charge density, and the EGL was represented as an array of periodically arranged circular cylinders of like charge, with a constant surface charge density. By combining the fluid mechanical analyses for the flow around a solute suspended in an electrolyte solution and the electrostatic analyses for the free energy of the …interaction between the solute and cylinders based on a mean field theory, we estimated the transport coefficients of the solute across the EGL. Both of diffusive and convective transports are reduced compared to those for an uncharged system, due to the stronger exclusion of the solute that results from the repulsive electrostatic interaction. The model prediction for the reflection coefficient for serum albumin agreed well with experimental observations if the charge density in the EGL is ranged from approximately −10 to −30 mEq/l. Show more

Keywords: Debye–Hückel equation, Boltzmann factor, reflection coefficient, hindrance factors

DOI: 10.3233/BIR-120620

Citation: Biorheology, vol. 49, no. 5-6, pp. 301-316, 2012

Authors: Rabai, Miklos | Meiselman, Herbert J. | Wenby, Rosalinda B. | Detterich, Jon A. | Feinberg, Jack

Article Type: Research Article

Abstract: Ektacytometry measures the shape of red blood cells under shear stress by analyzing the diffraction pattern of laser light passing through a thin layer of suspended cells. Here we model the diffraction pattern using a combination of Bessel and anomalous scattering functions, and employ a global pattern-fitting technique over nine different shear stresses to determine the separate mechanical properties of normal and non-deformable cells. This technique is capable of yielding the correct elongation index of the normal cells over a range of shear stresses even when they are mixed with as much as 50% non-deformable cells. Additionally, the relative concentrations …of normal and non-deformable cells can be determined. Show more

Keywords: Cell analysis, medical and biological imaging, light scattering

DOI: 10.3233/BIR-2012-0616

Citation: Biorheology, vol. 49, no. 5-6, pp. 317-328, 2012

Authors: Dörler, Jakob | Frick, Matthias | Hilber, Monika | Breitfuss, Harald | Abdel-Hadi, Mohammed N. | Pachinger, Otmar | Liepsch, Dieter | Schwarzacher, Severin P.

Article Type: Research Article

Abstract: Flow disturbance and reduced blood flow have been associated with higher restenosis rates and clinical adverse events after coronary interventions. In the present study, we sought to investigate flow alterations that occurred after stent implantation in a coronary model, within and adjacent to the stented segment. Two stents (Carbostent, Tetrastent) with different strut design were deployed in the left anterior descending artery (LAD) of a 1:1 scaled silicon coronary model. The model was mounted into an artificial circulation and showed distensibility and rheologic behavior comparable to human coronaries. Flow profiles were assessed using laser-Doppler anemometry. Both stents induced a transitional …flow within the stents, in the jailed branch as well as in the adjacent segments. However, the alterations in flow were less marked using the Carbostent having stents with thinner struts and a larger strut cell area, and thus seem to be more favorable in avoiding bifurcation lesions. This study shows precisely that stent implantation induces flow disturbances in segments known to be prone for restenosis. Investigations using laser-Doppler measurements may enlighten rheologic phenomena inducing restenosis and help in optimizing stent design and deployment techniques. Show more

Keywords: Coronary artery disease, flow disturbance, transitional flow, laser-Doppler anemometer

DOI: 10.3233/BIR-2012-0617

Citation: Biorheology, vol. 49, no. 5-6, pp. 329-340, 2012

Authors: Chen, Zengsheng | Zhang, Xiwen | Deng, Xiaoyan

Article Type: Research Article

Abstract: Adhesion of monocytes (U-937 cells) along a silicone tube deployed with circular ring stents was studied to test the hypothesis that by intentionally inducing swirling flow in an endovascular stent, the adhesion of monocytes would be suppressed. The results revealed that under a normal flow condition, the flow disturbance created by the circular ring stents enhanced the adhesion of U-937 cells in the silicone tube. By inducing a swirling flow in the silicone tube, the average wall shear stress (WSS) in the tube with the circular ring stents was elevated and significantly suppressed the adhesion density of U-937 cells to …the surface in the disturbed flow zones to a level equal to that when no stents were deployed in the tube. The results also showed that, due to the attenuation of the swirling flow along the tube, the adhesion density of U-937 cells increased monotonically along the tube, indicating that the adhesion density was negatively correlated with the strength of the swirling flow. Thus, the present study suggests that intentionally introducing swirling flow in an artery deployed with stents may be a solution to solve the problem of stent restenosis by restraining the adhesion of monocytes. Show more

Keywords: Stents, swirling flow, restenosis, monocyte adhesion

DOI: 10.3233/BIR-120622

Citation: Biorheology, vol. 49, no. 5-6, pp. 341-352, 2012

Authors: Naiki, Takeru | Kurose, Yuki | Hayashi, Kozaburo | Takumi, Hiroko | Kometani, Takashi

Article Type: Research Article

Abstract: Many people are sensitive to cold, resulting in poor blood circulation. There is evidence that hesperidin results in increased peripheral circulation and skin temperature. A transglycosylated hesperidin, α-glucosylhesperidin, is more bioabsorbable than hesperidin. In the present study, biomechanical studies were performed on the effects of long-term feeding of α-glucosylhesperidin on the contractile response (diameter response) and stiffness of femoral arteries excised from rabbits. Animals in the normal (non-treated), low, and high groups were fed 0, 150 and 4500 mg/day, respectively, of α-glucosylhesperidin for about 24 weeks. The feeding of α-glucosylhesperidin did not change arterial stiffness nor mean blood flow rate …in the femoral artery; however, it increased mean aortic blood pressure and decreased arterial diameter at 100 mmHg in the high group. The diameter responses developed by 10−5 M of norepinephrine were significantly lower in the high and low groups than in non-treated group. This result indicates that, due to the long-term feeding of α-glucosylhesperidin, arterial contraction induced by the neurotransmitter of sympathetic nerves decreases. It was estimated that blood flow in such muscular arteries as the femoral artery is maintained at normal by α-glucosylhesperidin even under the conditions of autonomic imbalance and cold intolerance. Show more

Keywords: Biomechanical tests, diameter response, contractile function, stiffness parameter, cold intolerance, flavonoids

DOI: 10.3233/BIR-2012-0619

Citation: Biorheology, vol. 49, no. 5-6, pp. 353-363, 2012

Authors: Dinardo, Carla Luana | Venturini, Gabriela | Omae, Samantha Vieira | Zhou, Enhua H. | da Motta-Leal-Filho, Joaquim Maurício | Dariolli, Rafael | Krieger, José Eduardo | Alencar, Adriano Mesquita | Costa Pereira, Alexandre

Article Type: Research Article

Abstract: One drawback of in vitro cell culturing is the dedifferentiation process that cells experience. Smooth muscle cells (SMC) also change molecularly and morphologically with long term culture. The main objective of this study was to evaluate if culture passages interfere in vascular SMC mechanical behavior. SMC were obtained from five different porcine arterial beds. Optical magnetic twisting cytometry (OMTC) was used to characterize mechanically vascular SMC from different cultures in distinct passages and confocal microscopy/western blotting, to evaluate cytoskeleton and extracellular matrix proteins. We found that vascular SMC rigidity or viscoelastic complex modulus (G) decreases with progression of passages. A …statistically significant negative correlation between G and passage was found in four of our five cultures studied. Phalloidin-stained SMC from higher passages exhibited lower mean signal intensity per cell (confocal microscopy) and quantitative western blotting analysis showed a decrease in collagen I content throughout passages. We concluded that vascular SMC progressively lose their stiffness with serial culture passaging. Thus, limiting the number of passages is essential for any experiment measuring viscoelastic properties of SMC in culture. Show more

Keywords: Cell culture, optical magnetic twisting cytometry, smooth muscle cells, dedifferentiation

DOI: 10.3233/BIR-120621

Citation: Biorheology, vol. 49, no. 5-6, pp. 365-373, 2012

Authors: Kumar, Bipin | Das, Apurba | Alagirusamy, R.

Article Type: Research Article

Abstract: Objective: To identify and analyze the important factors which could influence the Dynamic Stiffness Index (DSI) of compression bandages. Methods: Using three commercially available bandages with different stiffnesses, their DSI was obtained using a prototype based on an artificial leg-segment model consisting of a wooden mannequin having a variable circumference. The effect on DSI of three major factors, bandage extensibility (ε), resting pressure (RP) and limb circumference (C) was studied. An N-way ANOVA for a fixed model was carried out to test the significance of the above major factors and their interaction effects on bandage DSI. Results: There …were significant differences (p<0.05) between the mean DSI observed at different values of ε, RP and C. It was also found that some of the factors, ε and RP, and C and RP, interfere with each other and that their interaction effects also significantly affected the DSI (p<0.05). Conclusion: The above major factors have a deciding influence on the DSI of the compression bandages. Understanding the influence of these factors and the effect of their interactions on the DSI could help in pre-evaluating and comparing dynamic behaviors of different compression bandages during compression management. Show more

Keywords: Compression therapy, interface pressure, stiffness index, biomedical, compression bandages

DOI: 10.3233/BIR-2012-0618

Citation: Biorheology, vol. 49, no. 5-6, pp. 375-384, 2012

Article Type: Other

Citation: Biorheology, vol. 49, no. 5-6, pp. 385-387, 2012