Assay variables and early clinical evaluation of low-angle light scattering for platelet function analysis.

Introduction: The recently developed platelet aggregation technique based on low-angle light scattering (LaSca) in diluted platelet-rich plasma (PRP) requires only a small sample volume and provides information about platelet aggregation and shape change. This study aimed to investigate the influence of preanalytical and analytical variables and to validate the method in a real-life pediatric hematology hospital setting.

Methods: Platelet aggregation was induced by ADP in diluted PRP in the presence of 2 mM calcium at 23 °C.

Chloride Gradient Is Involved in Ammonium Influx in Human Erythrocytes.

The ammonia/ammonium (NH/NH, AM) concentration in human erythrocytes (RBCs) is significantly higher than in plasma. Two main possible mechanisms for AM transport, including simple and facilitated diffusion, are described; however, the driving force for AM transport is not yet fully characterized. Since the erythroid ammonium channel RhAG forms a structural unit with anion exchanger 1 (eAE1) within the ankyrin core complex, we hypothesized the involvement of eAE1 in AM transport.

ROS formation, mitochondrial potential and osmotic stability of the lamprey red blood cells: effect of adrenergic stimulation and hypoosmotic stress.

Semi-anadromous animals experience salinity fluctuations during their life-span period. Alterations of environmental conditions induce stress response where catecholamines (CA) play a central role. Physiological stress and changes in external and internal osmolarity are frequently associated with increased production of reactive oxygen species (ROS).

Hematin- and Hemin-Induced Spherization and Hemolysis of Human Erythrocytes Are Independent of Extracellular Calcium Concentration.

Pathologies such as malaria, hemorrhagic stroke, sickle cell disease, and thalassemia are characterized by the release of hemoglobin degradation products from damaged RBCs. Hematin (liganded with OH) and hemin (liganded with Cl)-are the oxidized forms of heme with toxic properties due to their hydrophobicity and the presence of redox-active Fe. In the present study, using the original LaSca-TM laser particle analyzer, flow cytometry, and confocal microscopy, we showed that both hematin and hemin induce dose-dependent RBC spherization and hemolysis with ghost formation.

Anticancer Drugs Paclitaxel, Carboplatin, Doxorubicin, and Cyclophosphamide Alter the Biophysical Characteristics of Red Blood Cells, In Vitro.

Red blood cells (RBCs) are the most numerous cells in the body and perform gas exchange between all tissues. During the infusion of cancer chemotherapeutic (CT) agents, blood cells are the first ones to encounter aggressive cytostatics. Erythrocyte dysfunction caused by direct cytotoxic damage might be a part of the problem of chemotherapy-induced anemia-one of the most frequent side effects.

Platelet Hemostasis Reactions at Different Temperatures Correlate with Intracellular Calcium Concentration.

Hypo- and hyperthermia affect both primary and secondary hemostasis; however, there are controversial data concerning platelet activation and the underlying mechanisms under hypo- and hyperthermia. The discrepancies in the data could be partly explained by different approaches to hemostatic reactions analysis. We applied a new LaSca-TMF laser particle analyzer for a simultaneous fluorescence and laser scattering analysis of platelet responses at different temperatures.

Persistent red blood cells retain their ability to move in microcapillaries under high levels of oxidative stress.

Oxidative stress is one of the key factors that leads to red blood cells (RBCs) aging, and impairs their biomechanics and oxygen delivery. It occurs during numerous pathological processes and causes anaemia, one of the most frequent side effects of cancer chemotherapy. Here, we used microfluidics to simulate the microcirculation of RBCs under oxidative stress induced by tert-Butyl hydroperoxide.

Cellular osmoregulation of the ark clam (Anadara kagoshimensis) hemocytes to hyposmotic media.

Many bivalve species are considered to be euryhaline organisms due to effective adaptation to fluctuations of environmental salinity. Cellular mechanisms responsible for tolerance to salinity changes remain unclear for bivalves despite this question being critically important for commercially cultured species frequently introduced into regions differing from natural habitat by salinity regime. In the present work laser diffraction method was used for the analysis of volume changes in hemoglobin-containing ark clam (Anadara kagoshimensis) hemocytes following hyposmotic stimulation.

Microfluidic Characterization of Red Blood Cells Microcirculation under Oxidative Stress.

Microcirculation is one of the basic functional processes where the main gas exchange between red blood cells (RBCs) and surrounding tissues occurs. It is greatly influenced by the shape and deformability of RBCs, which can be affected by oxidative stress induced by different drugs and diseases leading to anemia. Here we investigated how in vitro microfluidic characterization of RBCs transit velocity in microcapillaries can indicate cells damage and its correlation with clinical hematological analysis.

Curcumin by activation of adenosine A receptor stimulates protein kinase a and potentiates inhibitory effect of cangrelor on platelets.

Curcumin is a natural polyphenol derived from the turmeric plant (Curcuma longa) which exhibits numerous beneficial effects on different cell types. Inhibition of platelet activation by curcumin is well known, however molecular mechanisms of its action on platelets are not fully defined. In this study, we used laser diffraction method for analysis of platelet aggregation and Western blot for analysis of intracellular signaling mechanisms of curcumin effects on platelets.

Protein kinase A activity and NO are involved in the regulation of crucian carp (Carassius carassius) red blood cell osmotic fragility.

Activation of the cAMP pathway by β-adrenergic stimulation and cGMP pathway by activation of guanylate cyclase substantially affects red blood cell (RBC) membrane properties in mammals. However, whether similar mechanisms are involved in RBC regulation of lower vertebrates, especially teleosts, is not elucidated yet. In this study, we evaluated the effects of adenylate cyclase activation by epinephrine and forskolin, guanylate cyclase activation by sodium nitroprusside, and the role of Na/H-exchanger in the changes of osmotic fragility and regulatory volume decrease (RVD) response in crucian carp RBCs.

Ammonium Salts Promote Adaptive Changes of Rat Immune System to Ultimate Load in the Forced Swimming Model.

We studied the effect of different doses of ammonium chloride (ACl) and ammonium carbonate (ACr) on immunological parameters of the peripheral blood in rats during high-intensity exercise. Changes in the absolute and relative numbers of granulocytes, lymphocytes, natural killers, naive and mature effector cells one day after the end of the forced swimming cycle were found by using a hematological analyzer and a flow cytometer. Immunological indicators were analyzed relative to swimming duration on the last day of ultimate load.

Low-Dose Ammonium Preconditioning Enhances Endurance in Submaximal Physical Exercises.

Preconditioning is often used in medicine to protect organs from ischemic damage and in athletes to enhance the performances. We tested whether low-dose ammonium preconditioning (AMP) could have a beneficial effect on physical exercises (PE). We used Cardiopulmonary Exercise Testing (CPET) on a treadmill to investigate the effects of low-dose AMP on the physical exercise capacity of professional track and field athletes and tested twenty-five athletes.

Microvesicle Formation Induced by Oxidative Stress in Human Erythrocytes.

Extracellular vesicles (EVs) released by different cell types play an important role in many physiological and pathophysiological processes. In physiological conditions, red blood cell (RBC)-derived EVs compose 4-8% of all circulating EVs, and oxidative stress (OS) as a consequence of different pathophysiological conditions significantly increases the amount of circulated RBC-derived EVs. However, the mechanisms of EV formation are not yet fully defined.

Ammonium Salts Increase Physical Performance and Reduce Blood Lactate Level in Rats in a Model of Forced Swimming.

We compared the effects of two doses of ammonium chloride and ammonium carbonate (10 and 20 mg/kg) on the duration of swimming and blood lactate level. Ammonium chloride in a dose of 20 mg/kg was more efficient than in a dose of 10 mg/kg. The efficiency of ammonium carbonate in a dose of 10 mg/kg was similar to that of ammonium chloride in a dose of 20 mg/kg.

Ammonium Salts Promote Functional Adaptation of Rat Erythrocytes on the Model of Forced Swimming.

Ammonium, an end-product of catabolism, in low doses can promote adaptation of metabolic pathways in erythrocytes under conditions of extreme physical exercise. We compared the effects of two ammonium salts, ammonium chloride and ammonium carbonate, in two doses on biochemical parameters of rat erythrocytes 1 day after extreme physical exercise in a 4-week cycle of forced swimming. Of 16 analyzed parameters, the maximum number of significant shifts from the control was revealed in the groups of rats receiving ammonium chloride in doses of 20 and 10 mg/kg, and the minimal number of differences was found in groups treated with ammonium carbonate in the same doses.

GC-MS and LC-MS/MS pilot studies on the guanidine (N)-dimethylation in native, asymmetrically and symmetrically N-dimethylated arginine-vasopressin peptides and proteins in human red blood cells.

Protein-arginine methyltransferases catalyze the methylation of the guanidine (N) group of proteinic L-arginine (Arg) to produce monomethyl and dimethylarginine proteins. Their proteolysis releases the free amino acids monomethylarginine (MMA), symmetric dimethylarginine (SDMA) and asymmetric dimethylarginine (ADMA), respectively. MMA, SDMA and ADMA are inhibitors of the nitric oxide synthase (NOS) activity.

Hemoglobin deoxygenation and methemoglobinemia prevent regulatory volume decrease in crucian carp (Carassius carassius) red blood cells.

Fish red blood cells (RBCs) exhibit an oxygen-dependent regulatory volume decrease (RVD) in hypoosmotic environment. In higher vertebrates, membrane-associated hemoglobin is involved in the regulation of osmotic ion movements across the cellular membrane. However, whether the hemoglobin conformational state plays a role in the regulation of osmotic responses in fish red blood cells is still not fully understood.

Hypoxia inhibits the regulatory volume decrease in red blood cells of common frog (Rana temporaria).

Red blood cells of vertebrates can restore their cellular volume after hyposmotic swelling. The process strictly depends on oxygen availability in the environment. However, the role of hemoglobin in regulation of cell volume recovery is not clear yet.

Protein kinase A activation by the anti-cancer drugs ABT-737 and thymoquinone is caspase-3-dependent and correlates with platelet inhibition and apoptosis.

Chemotherapy-induced thrombocytopenia is a common bleeding risk in cancer patients and limits chemotherapy dose and frequency. Recent data from mouse and human platelets revealed that activation of protein kinase A/G (PKA/PKG) not only inhibited thrombin/convulxin-induced platelet activation but also prevented the platelet pro-coagulant state. Here we investigated whether or not PKA/PKG activation could attenuate caspase-dependent apoptosis induced by the anti-cancer drugs ABT-737 (the precursor of navitoclax) and thymoquinone (TQ), thereby potentially limiting chemotherapy-induced thrombocytopenia.

Temporal quantitative phosphoproteomics of ADP stimulation reveals novel central nodes in platelet activation and inhibition.

Adenosine diphosphate (ADP) enhances platelet activation by virtually any other stimulant to complete aggregation. It binds specifically to the G-protein-coupled membrane receptors P2Y1 and P2Y12, stimulating intracellular signaling cascades, leading to integrin αIIbβ3 activation, a process antagonized by endothelial prostacyclin. P2Y12 inhibitors are among the most successful antiplatelet drugs, however, show remarkable variability in efficacy.

Erythrocytes do not activate purified and platelet soluble guanylate cyclases even in conditions favourable for NO synthesis.

Background: Direct interaction between Red blood cells (RBCs) and platelets is known for a long time. The bleeding time is prolonged in anemic patients independent of their platelet count and could be corrected by transfusion of RBCs, which indicates that RBCs play an important role in hemostasis and platelet activation. However, in the last few years, opposing mechanisms of platelet inhibition by RBCs derived nitric oxide (NO) were proposed.

The sGC stimulator riociguat inhibits platelet function in washed platelets but not in whole blood.

Background And Purpose: Stimulation of soluble guanylyl cyclase (sGC) is a valuable therapeutic strategy for the treatment of several cardiovascular diseases. The sGC stimulator riociguat has been approved for the treatment of two forms of pulmonary hypertension. Platelets contain large amounts of sGC and play a key role in the regulation of haemostasis.

[The modification of method of erythrograms in patients under chronic hemodyalisis using hardware-controlled administration of laser low-angle light scattering].

The detailed analysis of structural characteristics of erythrocytes can be implemented with method of erythrograms. However its practical application in conditions of medical laboratory is a long and labor-intensive process of little avail for express-diagnostic. To register alterations of morphologic functional characteristics of erythrocytes in patients under chronic dialysis as compared with patients without renal pathology the new technique of low-angle light scattering never applied before for this purpose.