Development of experimental microfluidic device and methodology for assessing microrheological properties of blood.

Background And Objective: Microfluidics is a useful tool for investigating blood microrheology. The study aimed to present the development of a microfluidic device for assessing the microrheological properties of blood cells' suspensions and its application in patients with diabetes mellitus type 2 (T2DM).

Methods: A new microfluidic device was elaborated, connected to a system, including a microscope with a digital camera, a pump with a manometer and a computer with specially developed software.

Assessment of Fibrinogen Macromolecules Interaction with Red Blood Cells Membrane by Means of Laser Aggregometry, Flow Cytometry, and Optical Tweezers Combined with Microfluidics.

An elevated concentration of fibrinogen in blood is a significant risk factor during many pathological diseases, as it leads to an increase in red blood cells (RBC) aggregation, resulting in hemorheological disorders. Despite the biomedical importance, the mechanisms of fibrinogen-induced RBC aggregation are still debatable. One of the discussed models is the non-specific adsorption of fibrinogen macromolecules onto the RBC membrane, leading to the cells bridging in aggregates.

The Effects of Different Signaling Pathways in Adenylyl Cyclase Stimulation on Red Blood Cells Deformability.

Signaling pathways of red blood cells' (RBCs) micromechanics regulation, which are responsible for maintaining microcirculation, constitute an important property of RBC physiology. Selective control over these processes may serve as an indispensable tool for correction of hemorheological disorders, which accompany a number of systemic diseases (diabetes mellitus I&II, arterial hypertension, malaria, etc.).

Microcirculation and blood rheology abnormalities in chronic heart failure.

Background: Generalized restricted blood flow is hallmark of CHF of any etiology, but the extent of microcirculation restriction and the role of intrinsic blood properties in heart failure remains unknown.

Objective: The aim of this study was to estimate the microvascular blood flow and hemorheological properties in chronic heart failure to test the hypothesis that CHF patients have altered peripheral blood flow which contributes to the tissue perfusion disturbances.

Methods: Cutaneous microvascular blood flow was estimated by Laser Doppler and Optical Tissue Oximetry techniques.

Signaling pathways regulating red blood cell aggregation.

The exposure of red blood cells (RBC) to some hormones (epinephrine, insulin and glucagon) and agonists of α- and β-adrenergic receptors (phenylephrine, clonidine and isoproterenol) may modify RBC aggregation (RBCA). Prostaglandin E1 (PGE1) significantly decreased RBCA, and PGE2 had a similar but lesser effect. Adenylyl cyclase (AC) stimulator forskolin added to RBC suspension, caused a decrease of RBCA.

An effect of glycoprotein IIb/IIIa inhibitors on the kinetics of red blood cells aggregation.

The reversible aggregation of red blood cells (RBCs) continues to be of the basic science and clinical interest. Recently it has been reported about a specific binding between fibrinogen and unknown erythrocyte glycoprotein receptors. The aim of this study was to investigate whether the red blood cell aggregation (RBCA) include the cell-cell interaction using the membrane receptors that bind such ligands as fibrinogen or fibronectin.

Role molecular signaling pathways in changes of red blood cell deformability.

This study was designed to investigate the dependency of the red blood cell deformability upon activation of extra- and intracellular signaling pathways. Exposures of red blood cells (RBCs) to catecholamines and to insulin led to positive change in the RBC deformability. When forskolin, a stimulator of adenylyl cyclase (AC), was added to RBC suspension, the RBC deformability was increased.

Role Ca(2+) in mechanisms of the red blood cells microrheological changes.

To assess the physiological role of intracellular Ca(2+) in the changes of microrheological red blood cell (RBC) properties (RBC deformability and aggregation), we employed several types of chemicals that can increase and decrease of the intracellular Ca(2+) concentration. The rise of Ca(2+) influx, stimulated by mechanical loading, A23187, thrombin, prostaglandin F(2α) was accompanied by a moderate red cell deformability lowering and an increase of their aggregation. In contrast, Ca(2+) entry blocking into the red cells by verapamil led to a significant RBC aggregation decrease and deformability rise.

Macro- and microrheological parameters of blood in patients with cerebral and peripheral atherosclerosis: the molecular change mechanisms after pentoxifylline treatment.

This study was designed to evaluate hemorheological changes in patients with cerebrovascular disease (CVD) and peripheral arterial disease (PAD) after 4 weeks of pentoxifylline therapy as well as to study red blood cell microrheological variables after the cell incubation with pentoxifylline and some phosphodiesterase (PDE) activity inhibitors. The patients with CVD (n = 50) and PAD (n = 33) were treated with pentoxifylline (400 mg, thrice a day) for 4 weeks. Before and after drug therapy the hemorheological measurements including plasma and whole blood viscosity, red blood cell aggregation (RBCA) and deformability (RBCD) were completed.

Crosstalk between adenylyl cyclase signaling pathway and Ca2+ regulatory mechanism under red blood cell microrheological changes.

There are evidences that red blood cell (RBC) deformation and aggregation change under their incubation with catecholamines and it is connected with activation of intracellular signaling pathways. The present study was designed to explore the adenylyl cyclase signaling pathway and Ca2+ regulatory mechanism of RBCs together with their microrheological changes. The washed RBCs were resuspended in PBS.

Extra- and intracellular signaling pathways under red blood cell aggregation and deformability changes.

Exposure of red blood cells (RBCs) to catecholamines (epinephrine, phenylephrine, an agonist of alpha1-adrenergic receptors, clonidine, an agonist of alpha2-adrenergic receptors and isoproterenol, an agonist of beta-adrenergic receptors) led to change in the RBC microrheological properties. When forskolin (10 microM), an AC stimulator was added to RBC suspension, the RBC deformability (RBCD) was increased by 17% (p<0.05).

Hemorheological efficiency of drugs, targeting on intracellular phosphodiesterase activity: in vitro study.

This in vitro study was designed to examine changes of red cell microrheological parameters (red cell aggregation and their suspension viscosity) after cell incubation with some drugs having phosphodiesterase (PDE) inhibitory activity (pentoxifylline - 25.0 microg/ml; drotaverine - 10.0 microg/ml; vinpocetine - 5.

The effect of diuretics on red blood cell microrheological parameters in female hypertensive patients.

This study was designed to examine changes of hemorheological parameters and red cell aggregation particularly in essential arterial hypertension subjects receiving antihypertensive diuretic therapy. Fifty six female subjects were enrolled in this study. Thirty seven subjects (group I) were treated for four weeks with Hydrochlorothiaszide (25 mg/day); Nineteen patients (group II) were infused with dose of furosemide 40 mg i.

The effect of simvastatin therapy on hemorheological profile in coronary heart desease (CHD) patients.

This study was designed to examine changes of hemorheological parameters in patients with CHD and hypercholesterolaemia (wide range of plasma total cholesterol level from 5.6 to 9.8 mmol.

Effects of antihypertensive therapy on hemorheological profiles in female hypertensive patients with initially low or high whole blood viscosity.

This study was designed to examine changes of hemorheological parameters in essential arterial hypertension subjects following antihypertensive drug therapy. Eighty two female subjects were enrolled, and sub-divided into two groups based upon their high shear whole blood viscosity being lower (L) or higher (H) than normal controls. Equal numbers of L and H subjects were then treated for four weeks with one of four agents: angiotensin-converting enzyme inhibitor (ACE-inhibitor, Spirapril - 6 mg/day); calcium antagonist (Isradipin - 5 mg/day); beta-1-blocker (Talinolol - 100 mg/day); diuretic (Indapamide - 1.