Red Blood Cell Aggregation Research Articles

Probing Red Blood Cell Membrane Microviscosity Using Fluorescence Anisotropy Decay Curves of the Lipophilic Dye PKH26.

Red blood cell (RBC) aggregation and deformation are governed by the molecular processes occurring on the membrane. Since several social important diseases are accompanied by alterations in RBC aggregation and deformability, it is important to develop a diagnostic parameter of RBC membrane structural integrity and stability. In this work, we propose membrane microviscosity assessed by time-resolved fluorescence anisotropy of the lipophilic PKH26 fluorescent probe as a diagnostic parameter. We measured the fluorescence decay curves of the PKH26 probe in the RBC membrane to establish the optimal parameters of the developed fluorescence assay. We observed a complex biphasic profile of the fluorescence anisotropy decay characterized by two correlation times corresponding to the rotational diffusion of free PKH26, and membrane-bounded molecules of the probe. The developed assay allowed us to estimate membrane microviscosity ηm in the range of 100-500 cP depending on the temperature, which paves the way for assessing RBC membrane properties in clinical applications as predictors of blood microrheological abnormalities.

A mechanistic model of cross-bridge migration in RBC aggregation and disaggregation.

Red blood cells (RBCs) clump together under low flow conditions in a process called RBC aggregation, which can alter RBC perfusion in a microvascular network. As elevated RBC aggregation is commonly associated with cardiovascular and inflammatory diseases, a better understanding of aggregation is essential. Unlike RBC aggregation in polymer solutions which can be well explained by polymer depletion theory, plasma-mediated RBC aggregation has features that best match explanations with cross-bridging mechanisms. Previous studies have demonstrated the dominant role of fibrinogen (Fg) in promoting aggregate formation and recent cell-force spectroscopy (CFS) experiments on interacting RBC doublets in plasma have reported an inverse relationship between disaggregation force and the adhesive contact area between RBCs. This has led investigators to revisit the hypothesis of inter-RBC cross-bridging which involves cross-bridge migration under interfacial tension during the forced disaggregation of RBC aggregates. In this study, we developed the cross-bridge migration model (CBMM) in plasma that mechanistically represents the migrating cross-bridge hypothesis. Transport of mobile Fg cross-bridges (mFg) was calculated using a convection-diffusion transport equation with our novel introduction of convective cross-bridge drift that arises due to intercellular friction. By parametrically transforming the diffusivity of mFg in the CBMM, we were able to match experimental observations of both RBC doublet formation kinematics and RBC doublet disaggregation forces under optical tweezers tension. We found that non-specific cross-bridging promotes spontaneous growth of adhesion area between RBC doublets whereas specific cross-bridging tends to prevent adhesion area growth. Our CBMM was also able to correlate Fg concentration shifts from healthy population blood plasma to SLE (lupus) condition blood plasma with the observed increase in doublet disaggregation forces for the RBC doublets in SLE plasma.

SARS-CoV-2 Altered Hemorheological and Hematological Parameters during One-Month Observation Period in Critically Ill COVID-19 Patients.

Hematological and hemorheological parameters are known to be altered in COVID-19; however, the value of combined monitoring in order to deduce disease severity is only scarcely examined. A total of 44 acute SARS-CoV-2-infected patients (aCOV) and 44 age-matched healthy controls (Con) were included. Blood of aCOV was sampled at admission (T0), and at day 2 (T2), day 5 (T5), day 10 (T10), and day 30 (T30) while blood of Con was only sampled once. Inter- and intra-group differences were calculated for hematological and hemorheological parameters. Except for mean cellular volume and mean cellular hemoglobin, all blood cell parameters were significantly different between aCOV and Con. During the acute disease state (T0-T5), hematological and hemorheological parameters were highly altered in aCOV; in particular, anemic conditions and increased immune cell response/inflammation, oxidative/nitrosative stress, decreased deformability, as well as increased aggregation, were observed. During treatment and convalescence until T30, almost all abnormal values of aCOV improved towards Con values. During the acute state of the COVID-19 disease, the hematological, as well as the hemorheological system, show fast and potentially pathological changes that might contribute to the progression of the disease, but changes appear to be largely reversible after four weeks. Measuring RBC deformability and aggregation, as well as oxidative stress induction, may be helpful in monitoring critically ill COVID-19 patients.

Biospeckle laser as a tool to analyze erythrocyte aggregation

We analyze the erythrocyte aggregation by the biospeckle laser phenomenon and calculate characteristic parameters to develop non-invasive hemorheological techniques. Biospeckle is more complex than other light-based techniques, such as light transmission, providing information about the dynamics of the scatterers, their size, and morphology. Dextran 500 kDa combined with plasma and phosphate-buffered saline was used to induce controlled in vitro erythrocyte aggregation. Red blood cell aggregation was studied using an objective speckle setup in a microchip sample chamber. The speckle grain sizes were determined, and parameters to characterize the morphology of the erythrocyte aggregates were proposed. The inertia moment and the correlation coefficient were determined to assess the cells aggregation dynamics.

Relationship between red blood cell aggregation and dextran molecular mass

The aim of this study was to investigate the aggregation of red blood cells (RBCs) suspended in dextran solution at various levels of molecular mass. Dextran solutions at molecular mass 40, 70, 100 and 500 kDa at concentration from 2 to 5 g/dL were used to suspend the RBCs. The radius and velocity of sedimenting RBC aggregates were investigated using image analysis. The radius and sedimentation velocity of aggregates increased initially, then decreased after achieving maxima. The maximal velocity of RBC aggregates showed a bell-shaped dependence on dextran molecular mass and concentration, whereas maximal radius showed monotonic increase with both factors. Difference between aggregate and solution density was estimated using aggregate radius and sedimentation velocity and dextran solution viscosity, and was consistent across most molecular mass and concentration levels. This allowed to calculate the porosity of aggregates and to show that it monotonically decreased with the increase in the solution density, caused by the increase in the dextran concentration. The results provide insight into the RBC aggregation process in solutions of proteins of different size, reflecting various pathological conditions. The currently reported data can be potentially applied to specific pathophysiological conditions giving an interpretation that is not yet fully discussed in the literature.

Purine Nucleoside Phosphorylase Inhibition Attenuates the Progression of Anemia and Organ Damage in Sickle Cell Mice

Purine nucleoside phosphorylase (PNP) converts guanosine to guanine, inosine to hypoxanthine, and 2'-deoxyguanosine to guanine, and leads to the downstream formation of the pro-oxidant and vasculotoxic hypoxanthine and xanthine. Red blood cells are rich in PNP, yet PNP's role in the pathogenesis of sickle cell disease (SCD) is not known. Our group showed that patients with SCD have increased PNP release and activity, leading to accelerated guanosine/inosine metabolism and increased production of vasculotoxic hypoxanthine/xanthine (Bilan VP et al. 2018). Thus, we proposed that PNP may have a major pathogenic role in red blood cell sickling, hemolytic angioproliferation, cell aggregation and end organ damage, and that PNP inhibition may be beneficial in the treatment of SCD. The highly potent PNP inhibitor 8-aminoguanine is the product of the conversion of the endogenous guanosine metabolite and pro-drug 8-aminoguanosine (8-AG). We investigated the safety and efficacy of short-term (8 weeks) and chronic (20 weeks) treatment of Townes sickle mice (SS) and their non-sickling controls (AA) with 8-AG (60mg/kg/day administered ad libitum in the drinking water). We collected blood and urine samples at multiple intervals using metabolic cages. To determine 8-AG body disposition and PNP inhibition, urine samples were analyzed for purines by liquid chromatography - tandem mass spectrometry (LC-MS/MS). Both AA and SS mice tolerated 8-AG well with no evidence of toxicity. In both AA (n= 15) and SS (n=40) mice there was very efficient conversion of 8-AG that resulted in a 40-50-fold increase in urinary 8-aminoguanine concentrations (p<0.001). In 8-AG treated SS mice we observed reduced hypoxanthine levels, with an increased inosine/hypoxanthine ratio. Additionally, guanosine was increased, guanine was reduced, and an increased guanosine/guanine ratio was observed (p<0.05), suggesting potent PNP inhibition. In SS mice, the 8-week treatment with 8-AG significantly reduced hemoglobinuria (p<0.05) and albuminuria (p<0.05), attenuated left ventricular (LV, p<0.01) and right ventricular (RV, p<0.05) hypertrophy, limited hepatomegaly (p<0.001), and improved RV contractility (p<0.05), with a trend towards reduced lung weights and splenomegaly. In SS mice, 20-week treatment with 8-AG significantly slowed the progression of anemia as evidenced by attenuated age-related drops in hemoglobin and hematocrit levels, and it attenuated hemoglobinuria and albuminuria while significantly reducing splenomegaly (p=<0.05) and hepatomegaly (p<0.05, Figure). Semi-quantitative histopathological analysis suggested reduced iron deposition (Prussian blue stain, Figure), and reduced ischemic (H&E stain) and fibrotic (trichrome stain, Figure) injury in the spleen and liver from SS mice treated with 8-AG. Our data suggest that the PNP inhibitor 8-AG may have a pharmacological benefit in SCD and may warrant further investigation as a multi-pronged treatment approach for SCD. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Abstract 13538: Associations Between Circulating Liver Enzymes and Platelet Reactivity

Introduction: The liver plays an essential role in thrombopoiesis and coagulation, and circulating liver enzymes are associated with altered platelet counts. However, the role of liver enzymes in the modulation of platelet reactivity remains unclear. Methods: A total of 3,429 Framingham Heart Study participants were included in this study. Platelet reactivity to 8 agonists, including adenosine diphosphate (ADP), thromboxane A 2 mimetic (U46619) and arachidonic acid (AA), was measured using light transmission aggregometry (LTA), Multiplate impedance aggregometry and Optimul aggregometry. Platelet counts and platelet-red blood cell aggregates were enumerated using flow cytometry. Levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were also measured. Associations of platelet reactivity phenotypes with liver circulating liver enzyme levels analyzed using linear mixed-effects models and adjusted for sex, age, relatedness, smoking, aspirin-, and statin-use. To correct for multiple testing, a Bonferroni-correction threshold of P&lt;0.0011 was used to account for multiple comparisons. Results: Higher ALT levels were associated with platelet disaggregation in LTA to ADP (β=0.056, SE=0.02, P=3.54E-04), and with decreased platelet reactivity in response to U46619 in Optimul (EC 50 : β=0.064, SE=0.019, P=7.65E-04). Interestingly, higher AST levels were associated with decreased platelet counts (β=-0.082, SE=0.019, P=1.04E-05), platelet reactivity to U46619 (β=-0.069, SE=0.018, P=1.04E-04) and AA (β=-0.047, SE=0.013, P=3.12E-04), and circulating platelet-red blood cell aggregates (β=-0.062, SE=0.018, P=9.54E-04). Conclusion: Our findings suggest that ALT levels could alter primary platelet aggregation. AST may indirectly modulate platelet counts. In addition, lower AST levels may contribute to platelet hyperresponsiveness. Lastly, ALT and AST levels may have antagonistic effects on the formation of platelet and red blood cell aggregates, which may indirectly influence platelet margination within vessels. Additional studies are underway to examine whether liver fat, a marker of fibrosis associated with cardiovascular disease, is also associated with altered platelet function.

Phenomenological characterization of blood's intermediate shear rate: a new concept for hemorheology.

The phenomena of aggregation, breakdown, and disaggregation of the rouleaux of red blood cells (RBCs) in addition to deformability affect the human blood viscosity at different shear rates. In this study, the intermediate shear rate is introduced and defined when the effect of aggregation on the change of blood viscosity is diminished; and afterwards, the alteration in the blood viscosity is dominantly affected by the deformation of RBCs. With this respect, modeling the effective parameters on the blood shear-thinning behavior including hematocrit and plasma viscosity was performed for the two different shear regions discriminated by the proposed intermediate shear rates. The presented rheological model reflects a phenomenological approach to assess the human blood viscosity with an average error of ± 5% compared to experimental data for hematocrits between 0.299 and 0.702, subjected to various shear rates from 0.2 to 680 1/s. The temperature changes as well as biochemical effects on whole blood viscosity are characterized by the introduced plasma viscosity-dependent model. The presented comprehensive model could be used for better understanding of blood flow hemodynamics and analyzing the shear dependence of aggregation and deformability behaviors of RBCs.

Chronic cold agglutinin disease after a third COVID-19 mRNA vaccination.

COVID-19 mRNA vaccines manufactured by Pfizer-BioNTech and Moderna have been approved in many countries, and have been administered since 2020. Recent reports of mRNA vaccination exacerbating autoimmune hematologic disorders, such as immune thrombocytopenia or autoimmune hemolytic anemia, have caught the attention of the general public, resulting in alarm over the risks of serious consequences. Meanwhile, in very rare cases, vaccination was reported to trigger new onset of hemolytic anemia. However, it remains unknown whether this was a transient reaction or a persistent event, because all cases reported to date were immediately treated with corticosteroids or rituximab. Here, we present a case of newly diagnosed cold agglutinin disease after a third COVID-19 mRNA vaccination. The patient was followed for 4months without treatment and continued to exhibit high levels of cold agglutinin and aggregation of red blood cells. The present case indicates that the disease can become chronic, and provides insights into the pathogenesis and treatment strategies.

Erythrocyte aggregation in sudden flow arrest is linked to hyperthermia, hypoxemia, and band 3 availability

BackgroundErythrocyte aggregation is a phenomenon that is commonly found in several pathological disease states: stroke, myocardial infarction, thermal burn injury, and COVID‐19. Erythrocyte aggregation is characterized by rouleaux, closely packed stacks of cells, forming three‐dimensional structures. Healthy blood flow monodisperses the red blood cells (RBCs) throughout the vasculature; however, in select pathological conditions, involving hyperthermia and hypoxemia, rouleaux formation remains and results in occlusion of microvessels with decreased perfusion. ObjectivesOur objective is to address the kinetics of rouleaux formation with sudden cessation of flow in variable temperature and oxygen conditions. MethodsRBCs used in this in vitro system were obtained from healthy human donors. Using a vertical stop‐flow system aligned with a microscope, images were acquired and analyzed for increased variation in grayscale to indicate increased aggregation. The onset of aggregation after sudden cessation of flow was determined at proscribed temperatures (37–49°C) and oxygen (0%, 10%), and in the presence and absence of 4, 4′‐Diisothiocyano‐2,2′‐stilbenedisulfonic acid (DIDS). Both autologous and homologous plasma were tested. ResultsRBCs in autologous plasma aggregate faster and with a higher magnitude with both hyperthermia and hypoxemia. Preventing deoxyhemoglobin from binding to band 3 with DIDS (dissociates the cytoskeleton from the membrane) fully blocks aggregation. Further, RBC aggregation magnitude is greater in autologous plasma. ConclusionsWe show that the C‐terminal domain of band 3 plays a pivotal role in RBC aggregation. Further, aggregation is enhanced by hyperthermia and hypoxemia.

S3160 Sickle Hepatopathy: An Uncommon Sickle Cell Crisis

Introduction: Intrahepatic vaso-occlusive syndrome, or sickle cell hepatopathy (SCH), is a rare complication of sickle cell disease. We present a case of acute hepatic sequestration in the setting of bacteremia. Case Description/Methods: 32 male with history of sickle cell disease, auto-splenectomy and end stage renal disease presented with fatigue and diffuse myalgia. Physical exam was notable for scleral icterus, left knee swelling and erythema, and crackles in bilateral lungs. Initial labs showed leukocytosis (WBC 43,000/μL), profound anemia (Hgb 3.7 g/dL) and coagulopathy (INR 2.1). Liver enzymes were elevated at ALP 527 U/L, ALT 48 U/L, AST 209 U/L. Total bilirubin was 39 mg/dL with conjugated fraction 34.4 mg/dL, blood urea nitrogen 67mg/dL, creatinine of 4.34mg/dL, and ferritin >10,000. Blood cultures revealed Staphylococcus Aureus, likely due to left knee septic joint. US showed hepatomegaly with liver span of 24 cm. Clinical picture consistent with sepsis secondary to MSSA bacteremia in setting of sickle cell crisis and hepatopathy. Patient was admitted to ICU for hypoxic respiratory failure due to fluid overload. Clinical course was complicated by septic shock with multi-organ dysfunction including acute liver failure due to hepatic sequestration crisis, hemochromatosis, encephalopathy and disseminated intravascular coagulation. Patient required CRRT and supportive care including treatment of underlying infection, PRBC transfusions, and vitamin K administration to reverse coagulopathy (Figure). Discussion: Hepatopathy occurs in 10% of homozygous sickle cell patients. It can be self resolving or lead to fulminant hepatic failure. Subsets of SCH include Acute Hepatic Crisis(AHC), Hepatic Sequestration, Intrahepatic Cholestasis(IC). Sickling in the sinusoids leading to hepatocellular necrosis, engorgement of Kupffer cells and bile stasis. Common presentation of all three conditions includes acute RUQ pain, nausea, fever, and elevated liver enzymes. IC is severe presentation of SCH with hypoxic injury leading to blockage and cholestasis. Presentation overlaps with AHC with addition of hyperbilirubinemia, severe jaundice, renal impairment, and encephalopathy. Total bilirubin is typically markedly elevated due to combination of hemolysis, cholestasis and renal dysfunction. Sequestration presents with significant rapid onset hepatomegaly, drop in hemoglobin with RUQ pain, which can ultimately lead to cardiac and pulmonary instability. Treatment is supportive with exchange transfusion, fresh plasma for coagulopathy.Figure 1.: Top: Contrast enhanced spiral CT of the chest, abdomen and pelvis showing markedly enlarged measuring 20 cm in craniocaudal dimension with lobulated contour and non visualized spleen Bottom: Liver biopsy showing dilated sinusoids with aggregates of sickled red blood cells. There is also presence of canalicular cholestasis.

Investigation of formation and ultrasonic disassembling of RBC Aggregation aimed for maintenance of blood channel

AbstractEstablishment of real‐time monitoring technique for blood viscosity during extracorporeal circulation treatment is needed. We have demonstrated that red blood cell (RBC, hereafter) aggregation degree, which highly correlates with the blood viscosity, can be estimated by the ultrasound spectroscopic observation of the RBC and the defining of the peak frequency by the Fast Fourier Transform process. In this study, the peak frequency was measured to investigate the aggregation degree of RBC flowing in a simple heart‐lung machine. In addition, to disassemble the RBC aggregations that might cause the clogging of the circuit, a disassemble technique of the RBC aggregations using a focused 5 MHz ultrasonic transducer was also proposed. As the first step of this study, the disassembling of the RBC aggregations was carried out under the still condition and its effect was confirmed by the peak frequency method.

CFD MODELS FOR ANEURYSM ANALYSES AND THEIR USE IN IDENTIFYING THROMBOSIS FORMATION AND RISK ASSESSMENT

In this paper, the blood transport has been investigated using the single- and the two-phase methods. In the two-phase Euler–Euler approach, the blood is represented by two interpenetrating continua where the dispersed red blood cells (RBCs) of non-Newtonian characteristics are suspended in the continuous Newtonian plasma. The results of the two-phase model, where the RBC’s phase is assumed to be Carreau–Yasuda fluid, are validated against the experimental data. Furthermore, comparative analyses were performed in two patient-specific aneurysms, which indicated that for a given pulsatile flow rate, the two-phase blood approach is vitally advantageous over the single-phase assumption, and revealed a deeper inflow penetration, more complex flow structures and denser flow diversion zones in the aneurysm sac. It was obvious that the high OSI values calculated by the two-phase model covered much wider regions than the values predicted by the single-phase model. It was equally crucial that these regions coincided with the TAWSS values lower than the threshold that the single-phase approach can predict. Apparently, the single-phase model failed to spot sites of high rupture risk. The results were further exploited to identify the RBCs aggregation regions as, for example, the concave structures and narrow paths in the saccular aneurysms, for their possible use as the precursors of the thrombus formation.

Emerging functional microfluidic assays for the study of thromboinflammation in sickle cell disease.

This review briefly summarizes the significant impact of thromboinflammation in sickle cell disease in relation to recent advances in biomarkers that are used in functional microfluidic assays. Sickle cell disease (SCD) is an inherited hemoglobinopathy that affects 100 000 Americans and millions worldwide. Patients with SCD exhibit chronic haemolysis, chronic inflammation and thrombosis, and vaso-occlusion, triggering various clinical complications, including organ damage and increased mortality and morbidity. Recent advances in functional microfluidic assays provide direct biomarkers of disease, including abnormal white blood cell and red blood cell adhesion, cell aggregation, endothelial degradation and contraction, and thrombus formation. Novel and emerging functional microfluidic assays are a promising and feasible strategy to comprehensively characterize thromboinflammatory reactions in SCD, which can be used for personalized risk assessment and tailored therapeutic decisions.

Stimuli-Responsive Thiomorpholine Oxide-Derived Polymers with Tailored Hydrophilicity and Hemocompatible Properties.

Thermo-responsive hydrophilic polymers, including those showing tuneable lower critical solution temperature (LCST), represent a continuous subject of exploration for a variety of applications, but particularly in nanomedicine. Since biological pH changes can inform the organism about the presence of disequilibrium or diseases, the development of dual LCST/pH-responsive hydrophilic polymers with biological potential is an attractive subject in polymer science. Here, we present a novel polymer featuring LCST/pH double responsiveness. The monomer ethylthiomorpholine oxide methacrylate (THOXMA) can be polymerised via the RAFT process to obtain well-defined polymers. Copolymers with hydroxyethyl methacrylate (HEMA) were prepared, which allowed the tuning of the LCST behaviour of the polymers. Both, the LCST behaviour and pH responsiveness of hydrophilic PTHOXMA were tested by following the evolution of particle size by dynamic light scattering (DLS). In weak and strong alkaline conditions, cloud points ranged between 40–60 °C, while in acidic medium no LCST was found due to the protonation of the amine of the THOX moieties. Additional cytotoxicity assays confirmed a high biocompatibility of PTHOXMA and haemolysis and aggregation assays proved that the thiomorpholine oxide-derived polymers did not cause aggregation or lysis of red blood cells. These preliminary results bode well for the use of PTHOXMA as smart material in biological applications.

Hemostatic efficacy of composite polysaccharide powder (starch-chitosan) for emergency bleeding control: An animal model study

BackgroundBlood clot formation or hemostasis is vital to minimize blood loss and mitigate the risk of death from severe bleeding. This study investigates the characteristics of a novel hemostatic composite containing chemically modified chitosan and starch for emergency bleeding control. The performance of this novel hemostatic powder was compared with commercially available starch-based (Arista AH) and chitosan-based (Celox) hemostats. MethodsHemostatic composite was prepared according to the patent registered by the authors (Patent No. 100865, Iranian Intellectual Property Organization) in Bani Zist Baspar Healda, Inc. (Shiraz, Iran). The properties of the product were surveyed by Fourier-transform infrared spectroscopy and compared with Arista-AH and Celox as commercial counterparts. The cytocompatibility, hemolysis, platelet and red blood cells (RBCs) adhesion, biocompatibility, and biodegradability attributes were evaluated in in vivo and in vitro studies. Hemostatic efficacy was evaluated in 24 healthy 6-month-old male New Zealand white rabbits in lethal and sublethal injuries of femoral artery and veins, respectively. ResultsModification and composition led to a fundamental development in physicochemical characteristics including swelling properties, water absorption, and platelet and RBC adhesion due to improved electrostatic and hydrophilic attributes. The significant superiority in clotting efficiency was confirmed after the application of the composite in 2 models of venous and arterial injury in comparison with common commercial hemostats. ConclusionSimultaneous use of water-absorbing compounds and introducing positively charged functional groups to hemostatic material led to a considerable control of femoral bleeding in emergency conditions. The introduced composite was biodegradable and biocompatible and prompts RBC aggregation and platelet adhesion.

Estradiol Valerate Affects Hematological and Hemorheological Parameters in Rats.

Polycystic ovary syndrome (PCOS) is one of the most common endocrinological diseases in women. Although the risk of cardiovascular diseases is high in PCOS, the number of scientific publications describing hemorheological changes is not significant. We aimed to perform a comprehensive hematological and micro-rheological study on experimentally induced PCOS in rats.Wistar rats were divided into control (n = 9) and PCOS groups (n = 9), in which animals received single-dose estradiol valerate. Measurements were carried out before treatment and monthly for four months. Bodyweight, blood glucose concentration, hematological parameters, red blood cell (RBC) deformability, and aggregation were measured. A histological examination of the ovary was performed at the end of the experiment. The blood glucose level and the bodyweight were significantly elevated vs. base in the PCOS group. A significant decrease was seen in RBC count, hemoglobin, and hematocrit. The maximal elongation index showed a significant increase. PCOS also resulted in a significant increase in RBC aggregation index parameters. The histological and hormone examinations confirmed developed PCOS. The administration of estradiol valerate caused significant changes during the examined period in hematological and hemorheological parameters. Our results draw attention to the possible usefulness of micro-rheological investigations in further studies on PCOS.

Smartphone-based automated estimation of plasma creatinine from finger-pricked blood on a paper strip via single-user step sample-to-result integration

Measuring creatininelevels in blood plasma is one of the most commonly used means of routine monitoring of renal function. Point-of-care devicesfor creatinine level estimation potentially allow rapid measurement, facilitating continuous monitoring of vulnerable patients. However, a majority of such devices currently available is constrained by several factors such as lack of simplicity in fabrication and operation (including plasma separation), a limited regime of efficacy, compromised reagent stability, and elevated costs. Here, we report the invention of a simple-to-fabricate and easy-to-use paper strip for rapid evaluation of plasma creatinine levels (ranging from 0.1 to 15 mg dL-1) in an integrated single-step process. For the testing, one drop of whole blood is first dripped onto the calcium salt-functionalized sample pad of the strip. Subsequently, blood plasma separation occurs due to spontaneous aggregation of red blood cells (RBCs) in the presence of calcium ions. The plasma spontaneously traverses into the reaction zone of the test-strip via capillary action where it reacts with previously dispensed alkaline picrate reagent, resulting in a colorimetric signal. Smartphone-interfaced imaging and image analytics of the reaction spot renders the dissemination of the test result in a turn-around time of about 2–3 min, without necessitating additional device interfacing. High efficacy of performance is established by validating with the results obtained from laboratory-benchmarked biochemical auto-analyzer, exhibiting an accuracy of 94%, and the coefficient of variation ranging from 0.64 to 6.4%. Suitability of use in extreme resource-limited settings is established by favorable stability of the reagents outside controlled laboratory ambience and engagement of unskilled personnel to execute the testing procedure with uncompromised accuracy.

FEATURES OF THE PARAMETERS OF RED BLOOD CELLS AND HEMOSTASIS IN PATIENTS WITH STROKES ASSOCIATED WITH CORONAVIRUS INFECTION

Objective: The purpose is to identify the peculiarities of the parameters of red blood cells (RBC) and hemostasis in patients with strokes associated with coronavirus infection. Design and method: A total of 124 patients (48.5 + 1.9 years) with impairments of cerebral circulation due to COVID-19 (confirmed by positive PCR test) had been examined. Among them, 74 patients had ischemic stroke, 25– transient ischaemic attack, 17– intracerebral hemorrhage, 8– subarachnoid hemorrhage. The parameters of hemostasis were measured by standard methods, electrical, viscoelastic parameters of RBC - by dielectrophoresis. Results: 71 patients (the 1st group) showed signs of intravascular coagulation and thrombosis: accelerated platelet-leukocyte aggregation, increased levels of coagulation products, reduced fibrinolysis activity (p = 0.001–0.04). The levels of D-dimer, fibrinogen, ESR, platelet count were higher in this group compared to the second one (p &lt; 0.01). A moderate increase of RBC summarized rigidity, viscosity was noted. The level of RBC hemolysis was associated with platelet count (r = 0.735,p = 0.03), D-dimer (r = 0.482, p &lt; 0.05), fibrinogen level (r = 0.374, p = 0.04). In 2nd group (53 persons), the markers of thrombosis had moderate deviations. Sharply reduced RBC deformability with increased summarized rigidity, viscosity was dominant coupled with the background of high electrical conductivity of cell membranes compared to the indicators in the 1st group (p &lt; 0.01). There was a decrease of membrane capacity, surface charge, cell dipole moment, polarizability than those in the 1st group (p = 0.0001–0.05). A sharp decrease of RBC deformability creates obstacles to overcoming small-diameter capillaries, leading to violations of microcirculatory blood flow. RBC deformability was associated with levels of ferritin (r = 0.451, p = 0.02), HbA1c (r = 0.480, p = 0.03), uric acid (r = -0.371, p &lt; 0.05), LDL cholesterol (r = 0.461, p = 0.02). Incubation of blood samples in vitro for 10 min with riboflavin, nicotinamide, inosine, which ensures RBC energy metabolism, restored the reduced RBC deformability (p &lt; 0.01), altered cell morphology (p = 0.04), decreased RBC aggregation (p &lt; 0.001). Conclusions: The revealed features of parameters of RBC hemostasis in stroke patients with coronavirus infection are associated with two independent pathogenetic mechanisms: thrombotic and hemorheologic. The thrombotic variant is due to procoagulant state and an activity of inflammation. The hemorheologic variant is caused by decrease of RBC energy metabolism, activity of enzymes.

Investigation of Formation and Ultrasonic Disassembling of Red Blood Cell Aggregation Aimed for Maintenance of Blood Channel

Investigation of Formation and Ultrasonic Disassembling of Red Blood Cell Aggregation Aimed for Maintenance of Blood Channel