Biorheology - Volume 56, issue 4

Authors: Tabatabaei, Mohammad | Tafazzoli-Shadpour, Mohammad | Khani, Mohammad Mehdi

Article Type: Research Article

Abstract: BACKGROUND: Cancerous transformation of cells affects their mechanical behavior and cytoskeleton structure. OBJECTIVE: The objective of this research is to investigate a correlation between mechanical properties and cytoskeletal structure features in cancer cell formation. METHODS: Micropipette aspiration was used to compare mechanical properties of normal (MCF10A) and cancerous (T47D) epithelial breast cell lines. Immunofluorescence and confocal microscopy were employed for staining and imaging F-actin and microtubules, and quantifying their fluorescent intensity, anisotropy and fiber distribution. RESULTS: Results indicated higher F-actin intensity (43%) and anisotropy (50%) in normal cells compared to cancer cells, although there …was no difference in the microtubules intensity between cell lines. Furthermore, reductions of cortex thickness and actin layer index (60%) were observed in suspended cancer cells compared to normal cells. Changes in cell physical properties induced by cancer were attributed to microtubules. The arranged fibrous structure of microtubules in normal cells was replaced by a disorganized structure in cancer cells. Cancerous cells were about four times softer with higher creep compliance compared to normal cells. CONCLUSIONS: Results of this study confirmed that alterations in cell mechanical properties induced by cancer are highly correlated with changes in F-actin and microtubule content and arrangement. It is suggested that such changes can enhance our knowledge of cancer initiation and progression. Show more

Keywords: Cytoskeleton structure, mechanical properties, micropipette aspiration, MCF10A, T47D

DOI: 10.3233/BIR-190214

Citation: Biorheology, vol. 56, no. 4, pp. 207-219, 2019

Authors: Cirrik, Selma | Ugurel, Elif | Aksu, Ali Cenk | Oronsky, Bryan | Cabrales, Pedro | Yalcin, Ozlem

Article Type: Research Article

Abstract: BACKGROUND: RRx-001 is an anti-cancer immunotherapeutic that increases the sensitivity of drug resistant tumors via multiple mechanisms which involve binding to hemoglobin and enhancing nitrite reductase activity of deoxyhemoglobin. OBJECTIVE: In the present study, the effect of clinically used doses of RRx-001 on erythrocyte deformability was examined. METHODS: A dose dependent effect of RRx-001 (1-1000 micro molar) on erythrocyte deformability was measured by ektacytometer under hypoxia (n = 8). Low dose RRx-001 (20 micro molar) in the presence of ODQ (1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one), L-NAME (L-NG-Nitroarginine methyl ester) or nitrite were examined both in normoxia and hypoxia. Intracellular nitric …oxide (NO) levels were measured fluorometrically with DAF-FM-DA. RESULTS: Higher doses of RRx-001 (100, 1000 micro molar) significantly decreased erythrocyte deformability under hypoxia (p < 0.01; p < 0.05, respectively). RRx-001 (20 micro molar), alone or in combination with ODQ or L-NAME, did not change deformability. However, RRx-001 and nitrite caused an increase in deformability (p < 0.01) under hypoxia. RRx-001 induced NO production was more pronounced in the presence of nitrite (p < 0.05). CONCLUSIONS: Co-administration of RRx-001 and nitrite under hypoxic conditions results in a significant increase in erythrocyte deformability that is related to increased NO production. We suggest that measurement of serum nitrite level in RRx-001 treated cancer patients should be routinely undertaken and supplemented if levels are low for maximal activity. Show more

Keywords: RRx-001, nitric oxide, erythrocyte, deformability, hypoxia

DOI: 10.3233/BIR-190213

Citation: Biorheology, vol. 56, no. 4, pp. 221-235, 2019

Authors: Minh, Nguyen Ngoc | Obara, Hiromichi | Shimokasa, Kenji | Zhu, Junfang

Article Type: Research Article

Abstract: BACKGROUND: Bile, which is secreted by the liver, is essential for digesting fat and maintaining homeostasis. Although the rheology of bile is very important to its flow, its extensional viscosity has not been studied. OBJECTIVE: We investigated the stretching of bile and evaluated its extensional viscosity using a filament-breakup device. METHODS: A liquid bridge formed between the endplates of the filament-breakup device. The midpoint diameter of the bridge was recorded by a laser micrometer. The filament self-thinning was captured by a high-resolution, high-speed camera. We used the liquid bridge diameter to evaluate the extensional viscosity of …bile. RESULTS: All samples show shear-thinning and viscoelasticity. Bile sediment has much greater viscosity and stretches more than bile solution. Filament thinning takes a long time for bile sediment and a short time for solution. The global function for the mid-filament diameter can be used to predict the evolution of the filament diameter of the liquid bridge and the trend of the extensional viscosity of bile. CONCLUSIONS: The extensional viscosity of bile is much greater than its shear viscosity. Because mucus concentration makes bile sediment more viscous than the solution, bile viscosity can increase sharply, thereby increasing risks of such diseases as gallstones and sludge buildup in the biliary system. Show more

Keywords: Stretching, shear-thinning, filament liquid bridge, mucus

DOI: 10.3233/BIR-190216

Citation: Biorheology, vol. 56, no. 4, pp. 237-252, 2019

Authors: Lu, Sen | Zhang, Shusheng

Article Type: Research Article

Abstract: BACKGROUND: Atherosclerotic lesions develop preferentially at certain sites in the human arterial system, such as the inner wall of curved segments and the outer wall of bifurcations. Local wall shear stress (WSS) and concentration of low density lipoprotein (LDL) have been identified as two important factors contributing to these lesions. OBJECTIVE: To determine if a connection exists between arterial curvature and the formation of atherosclerosis. METHODS: A set of 3-D vessel models with different bend angles was constructed. By comparing blood flow, WSS, and LDL aggregation, the influence of bend curvature on atherosclerotic lesions was assessed. …RESULTS: Upon increasing arterial bending, low WSS regions were formed at the outer wall of the junction between straight and curved segments, as well as the inner wall of curved segments. However, high LDL concentrations only appeared at the inner wall of the bend region. A connection between secondary flow and LDL concentration was observed; high LDL concentration regions had stronger secondary flow. Higher water infiltration velocity could enhance LDL aggregation, while blood non-Newtonian properties, by easing secondary flow, diminished its aggregation. CONCLUSIONS: Under the same flow rate, a larger bend angle increased flow resistance, lowered WSS, and increased LDL surface concentrations, thus indicating an increased risk of atherosclerosis. Show more

Keywords: Bend angle, wall shear stress, concentration polarization, secondary flow

DOI: 10.3233/BIR-190215

Citation: Biorheology, vol. 56, no. 4, pp. 253-263, 2019