Search Results (259)

Background and Objectives: Whole Blood Viscosity (WBV), estimated using the De Simone formula, is a key hemodynamic parameter linked to endothelial dysfunction and atherosclerosis. Its association with significant coronary calcification, defined as a high Coronary Artery Calcium Score (CACS ≥ 100), remains unclear. This study investigated whether calculated WBV predicts high CACS. Materials and Methods: In this single-center, retrospective, cross-sectional study, 403 patients undergoing coronary computed tomography angiography for suspected stable coronary artery disease were included. Participants were stratified into CACS < 100 (n = 258) and CACS ≥ 100 (n = 145). WBV was calculated at High Shear Rate (HSR) and Low Shear Rate (LSR) using the De Simone formula. Multivariate binomial logistic regression adjusted for conventional cardiovascular risk factors was used to identify independent predictors of high CACS. Results: Patients with CACS ≥ 100 were older, more frequently male, and had a higher prevalence of diabetes and hypertension (all p < 0.01). Mean WBV did not differ significantly between groups: WBV-HSR, 4.3 ± 0.5 cP vs. 4.4 ± 0.5 cP (p = 0.456); WBV-LSR, 29.9 ± 8.0 cP vs. 30.4 ± 8.6 cP (p = 0.505). In multivariate models, neither WBV-HSR (OR: 0.489; p = 0.462) nor WBV-LSR (OR: 0.987; p = 0.520) independently predicted high CACS. Age and sex were the strongest independent predictors (p < 0.001). Conclusions: No independent association was found between calculated WBV and high CACS in this cross-sectional study. Full article

Elevation in the level of whole blood viscosity (WBV) is a known contributor to cardiovascular risk. Moreover, cardiovascular diseases are associated with seasonal variation and the potential impact of seasonal changes on blood viscosity, and associated biomolecules pose substantial cardiovascular risk and are therefore a subject of interest. To evaluate the effect of seasonal changes on whole blood viscosity, glycated haemoglobin and associated biomolecules, namely haematocrit and serum total protein, and their implications on management of diabetic cardiovascular risk are explored. This was a clinical laboratory retrospective observational study involving 10-year pathology data (1999–2008) which estimated whole blood viscosity (eWBV) and the associated biomolecules, namely haematocrit and serum total protein. Comparisons were made between seasonal changes and glycated haemoglobin, whole blood viscosity, haematocrit, and serum total protein levels. Whole blood viscosity, haematocrit, and serum total protein levels increased with colder seasons (p < 0.001), peaking in the winter. However, the seasonal variation in the level of glycated haemoglobin did not achieve statistical significance. Blood viscosity fluctuates between seasons, with peaks occurring in the winter season. This fluctuation will assist in adjusting monitoring and treatment strategies of diabetic risks seasonally. In addition, recognition of seasonal variations will help in precise risk assessment of timely interventions to mitigate the risk of cardiovascular events in diabetes management. Full article

The paper provides a comprehensive review of the relationship between whole blood viscosity (WBV) and acute ischemic stroke (AIS) concerning AIS risk and type, and its treatment and prognosis. A significant increase in diastolic blood viscosity (DBV) at the onset of AIS was established in the small-artery occlusion stroke subtype. In patients with atherothrombotic causes of AIS, systolic (SBV) and DBV values were higher than in those with an embolic cause. The higher WBV at low shear rates on hospital admission is associated with an increased risk of early neurological deterioration and disease progression in the patients with AIS. Most studies reveal the association of increased WBV at the stroke onset with poor functional outcome after applying intravenous thrombolysis or endovascular thrombectomy. However, significant reduction in WBV after the combined use of these therapeutic methods in AIS patients was observed. Whole blood viscosity has an obvious effect on the risk of AIS, its clinical severity and outcome. Further research is needed due to the multiple devices and techniques used, like cone–plate viscometers, scanning capillary viscometers, EMS viscometers, parallel-plate rheometers and the different associations of WBV with some of the applied treatment strategies. Full article

Background: The relationship between glycaemia and the variables of haematocrit, serum total protein and lipids possibly plays a role in pathological processes and hence is a subject of interest. Estimated blood viscosity causes impaired blood flow and is a factor in other vascular diseases. Blood viscosity is correlated with glycated haemoglobin, but the mechanism of this association has not been extensively investigated. Objective: To assess if changes in glycated haemoglobin translate into changes in blood viscosity through impact on haematocrit, serum protein or dyslipidaemia. Method: This was a clinical laboratory-based retrospective data analysis of patients attending a diabetic clinic. Analysis involved seven variables comprising serum total protein level, high-density lipoprotein cholesterol, total cholesterol, triglyceride, age and glycated haemoglobin. The statistical evaluations were descriptive, comparative and correlational. Results: A total of 12,986 sets of data represented the participants in this study. After excluding three with incomplete data of interest, the groups that were created for comparison comprised the following: good glycaemic control (2694), moderate glycaemic control (4075) and poorly controlled (6194). Serum levels of high-density lipoprotein cholesterol, total cholesterol, haematocrit and proteinaemia gradually decreased with worsening glycaemic control, while serum triglyceride and age increased. In the correlation analysis, serum triglyceride level was positively correlated with glycated haemoglobin r = 0.177, while haematocrit and proteinaemia were negatively related, at −0.045 and −0.103, respectively. Conclusions: Increase in glycated haemoglobin was inversely related to haematocrit and proteinaemia; therefore, this did not always increase with the determinants of estimated whole blood viscosity. The implication of this is that further studies are required to substantiate the observation of higher whole blood viscosity levels in patients with poorly controlled diabetes. Full article

Background: Chronic venous insufficiency (CVI) is one of the main causes of venous leg ulcers. Rheological disorders of the blood, such as changes in viscosity, hematocrit, and erythrocyte aggregation and deformability, can impair microcirculation and impede healing. Carbonic acid (CO₂) dry baths are a non-invasive physical method that can affect microcirculation and blood parameters, and this study aimed to assess their effectiveness in ulcer healing and in modifying selected blood rheological parameters in patients with CVI. Methods: This prospective, controlled study enrolled 23 participants (11 patients with active venous leg ulcers and 12 healthy controls). The intervention group underwent ten sessions of dry CO₂ baths, performed twice weekly for 5 weeks. No randomization was applied. Ulcer healing was assessed planimetrically, and blood rheological parameters (hematocrit, blood and plasma viscosity, erythrocyte deformability index [EI], aggregation index [AI], aggregation amplitude [AMP], and half-time of aggregation [T_1/2]) were measured before and after therapy. Results: Following the intervention, the ulcer area decreased significantly (median 3.35 cm² to 1.74 cm²; p < 0.01), as did ulcer circumference (7.33 cm to 5.87 cm; p < 0.01). Hematocrit increased (median 40.25% to 41.50%; p < 0.05), and blood viscosity values at low shear rates approached those of the control group. In contrast, erythrocyte deformability (EI) and aggregation indices (AI, AMP, T_1/2) showed no statistically significant intragroup changes, although intergroup differences persisted. Pain intensity decreased significantly (VAS 6.0 to 3.5 cm; p < 0.05). Conclusions: CO₂ dry baths support the treatment of venous ulcers by improving microcirculation and reducing pain. Their impact on blood rheology may have clinical significance, especially as an adjunct to therapy in chronic venous insufficiency. However, the relatively small sample size (n = 23) should be considered a limitation when interpreting these findings. Full article

This study describes the design and validation of an experimental setup for testing photoplethysmographic (PPG) devices intended for the non-invasive monitoring of vascular accesses in hemodialysis patients. Continuous assessment of arteriovenous fistulas is essential to detect pathological conditions such as stenosis, which can compromise patient safety and dialysis efficacy. While PPG-based sensors are capable of detecting such anomalies, their clinical applicability must be supported by controlled in vitro validation. The developed system replicates the anatomical, mechanical, optical, and hemodynamic features of vascular accesses. A 3D fistula model was designed and fabricated via 3D printing and silicone casting. The hydraulic circuit used red India ink and a PWM-controlled pump to simulate physiological blood flow, including stenotic conditions. Quantitative validation confirmed anatomical accuracy within 0.1 mm tolerance. The phantom exhibited an average Shore A hardness of 20.3 ± 1.1, a Young’s modulus of 10.4 ± 0.9 MPa, and a compression modulus of 105 MPa—values consistent with soft tissue behavior. Burst pressure exceeded 2000 mmHg, meeting ISO 7198:2016 standards. Flow rates (400–700 mL/min) showed <1% error. Compliance was 2.4 ± 0.2, and simulated blood viscosity was 3.9 ± 0.3 mPa·s. Systolic and diastolic pressures fell within physiological ranges. Photoplethysmographic signals acquired using a MAX30102 sensor (Analog devices Inc., Wilmington, MA, USA) reproduced key components of in vivo waveforms, confirming the system’s suitability for device testing. Full article

Physical activity influences red blood cell (RBC) deformability and aggregation, which affect oxygen transport and performance. While regular training may enhance RBC properties, adaptations depend on exercise intensity, duration, and recovery. This study aimed to assess the impact of a 12-week core muscle training program on RBC deformability, aggregation, and aerobic capacity in military trainees. A total of 35 male volunteers were divided into a Training group (n = 17) and a Control group (n = 18). The intervention included dynamic stretching, core stabilization, and functional movement exercises. Spiroergometry tests, blood gas analysis, and hemorheological measurements were conducted before and after the program. Results showed no significant changes in body composition or aerobic capacity. RBC deformability slightly decreased after exercise in both groups, while RBC aggregation increased. Blood viscosity changes were more moderate in the Training group, suggesting potential adaptation. However, the training intensity may have been insufficient for significant hemorheological improvements. While regular physical activity can enhance RBC function, adequate intensity, recovery, and nutrition are essential for optimal adaptation. Individualized training strategies should consider these factors to maximize performance and hemorheological benefits. Full article

The incorporation of apple bagasse (AB), a by-product of juice extraction, into apple juice can enhance its nutritional value while reducing food waste. This study investigated the effects of enzymatic hydrolysis (EH) and ultrasonic pre-treatment (US) on AB-enriched apple juice, focusing on its physicochemical, functional, and health-promoting properties. Apple juice was fortified with AB (1.5%, 3%, 4.5%) and subjected to EH using a cellulase-pectinase mixture for different durations (2, 6, 24 h). Optimal EH conditions (2 h, 3% AB) were combined with US (400 W, 8 min). Key parameters were analyzed, including total phenolic content, antioxidant activity, and glycemic response, alongside sensory evaluation. EH reduced particle size (D₅₀), viscosity, and pH, while increasing GalA content, with effects intensifying over time. US further decreased D₅₀ by 25.4% and viscosity by 39.7% but had no impact on other properties. Juices with 3% and 4.5% AB had over twice the phenolic content and 2.5–3× higher antioxidant activity. They also exhibited a potential hypoglycemic effect, with enhanced in vitro glucose retardationand lower blood glucose levels in 10 individuals. In conclusion, AB-enriched apple juice, treated with US and EH, showed higher nutritional value while maintaining acceptable sensory properties. Full article

The present study aims to optimize the extraction process and systematically investigate the bioactivity of polysaccharides derived from Peristrophe roxburghiana (Schult.) Brem. (CPPRs). To this end, the Box–Behnken design–response surface methodology was employed to optimize the extraction parameters of polysaccharides. The optimal extraction conditions were as follows: extraction temperature, 84 °C; extraction duration, 208 min; liquid-to-material ratio, 1:27 g/mL; extraction times, 4 times. The maximum extraction yield reached 17.89%, and the yield under non-optimal extraction conditions is 11–16%. This study systematically investigated the polysaccharides’ physicochemical, structural, and morphological properties using multiple advanced techniques (FTIR, SEM, XRD, HPLC, rheology, and TGA). CPPRs are primarily composed of arabinose, galactose and glucose as the main monosaccharides, amorphous, and capable of low-viscosity gels at low shear rates. Furthermore, CPPRs displayed notable antioxidant activity in vitro, scavenging ABTS^•+ and DPPH^• and reducing Fe³⁺ (with scavenging/reducing rates exceeding 40% at a concentration of 1 mg/mL). Meanwhile, 3 mg/mL CPPRs reduced oxidative damage of red blood cells induced by AAPH, scavenging more than 50% of ROS, and reducing the hemolysis rate by 94.5%. Additionally, CPPRs significantly promoted secretion of cytokines (including TNF-α, IL-6, and IL-10) and NO in RAW264.7 macrophages in vitro compared with the untreated control group. These findings collectively highlight the potential of CPPRs—possessing both antioxidant and immune-enhancing properties—as promising functional ingredients for application in the food and pharmaceutical industries. Full article

The aim of this study was to evaluate the effect of human blood contamination, before and after hardening of the materials, on microhardness of high-viscosity Fuji IX GP Extra (Fuji IX) and resin-modified Fuji II LC (Fuji II) glass-ionomer cement (GIC) and glass-hybrid material EQUIA Forte HT (EQUIA), with and without protective coating EQUIA Forte Coat (Coat), before and after thermocycling. Four groups (n = 40): 1. Fuji IX; 2. Fuji II; 3. EQUIA and 4. EQUIA + Coat were further subdivided into 3 subgroups: (1) Control; (2) blood contamination before hardening; (3) blood contamination after hardening, resulting in a total of 12 groups of 10 samples each. Samples were prepared using teflon molds (5 mm × 2 mm). Microhardness was measured using a Vickers microhardness tester before and after thermocycling (10,000 cycles), and data were statistically analyzed (Kolmogorov–Smirnov test, ANOVA, Scheffe’s test). In the control groups, the highest microhardness was measured for EQUIA+Coat before thermocycling (70.71 ± 8.79) and after thermocycling (68.6 ± 7.65). Within the groups exposed to blood after hardening, the highest microhardness was recorded in the thermocycled EQUIA+Coat group (73.07 ± 8.85). Blood contamination before hardening negatively affected the microhardness of Fuji II, Fuji IX, and EQUIA+Coat. Exposure to blood after hardening increased the microhardness of Fuji IX and EQUIA, thermocycled Fuji IX and thermocycled EQUIA + Coat samples. Full article

Predicting absolute values of hemolysis using the power law model to guide medical device design is hampered by uncertainties stemming from four sources of model inputs: incoming/upstream velocity profiles, blood viscosity models, power law hemolysis coefficients, and obtaining accurate stress exposure times. Amidst all these uncertainties, enabling rapid assessments and predictions of relative hemolysis would still be valuable for evaluating device design prototypes. Towards achieving this objective, hemolysis data from the Eulerian modeling framework was first generated from computational fluid dynamics simulations encompassing five blood viscosity models, four sets of hemolysis power law coefficients, fully developed as well as developing velocity flow conditions, and a wide range of shear stresses, strain rates, and stress exposure times. Corresponding hemolysis predictions were also made in a Lagrangian framework via numerical integration of shear stress and residence time spatial variations under the assumption of fully developed Newtonian fluid flow. Absolute hemolysis predictions (from both frameworks) were proportional to each other and independent of the blood viscosity model. Further, relative hemolysis trends were not dependent on the hemolysis power law coefficients. However, accuracy in wall shear stresses in developing flow conditions is necessary for accurate relative hemolysis assessments. Full article

Red blood cell (RBC), accounting for approximately 45% of total blood volume, are essential for oxygen delivery and carbon dioxide removal. Their unique biconcave morphology, high surface area-to-volume ratio, and remarkable deformability enable them to navigate microvessels narrower than their resting diameter, ensuring efficient microcirculation. RBC deformability is primarily determined by membrane viscoelasticity, cytoplasmic viscosity, and cell geometry, all of which can be altered under various physiological and pathological conditions. Reduced deformability is a hallmark of numerous diseases, including sickle cell disease, malaria, diabetes mellitus, sepsis, ischemia–reperfusion injury, and storage lesions in transfused blood. As these mechanical changes often precede overt clinical symptoms, RBC deformability is increasingly recognized as a sensitive biomarker for disease diagnosis, prognosis, and treatment monitoring. Over the past decades, diverse techniques have been developed to measure RBC deformability. These include single-cell methods such as micropipette aspiration, optical tweezers, atomic force microscopy, magnetic twisting cytometry, and quantitative phase imaging; bulk approaches like blood viscometry, ektacytometry, filtration assays, and erythrocyte sedimentation rate; and emerging microfluidic platforms capable of high-throughput, physiologically relevant measurements. Each method captures distinct aspects of RBC mechanics, offering unique advantages and limitations. This review synthesizes current knowledge on the pathophysiological significance of RBC deformability and the methods for its measurement. We discuss disease contexts in which deformability is altered, outline mechanical models describing RBC viscoelasticity, and provide a comparative analysis of measurement techniques. Our aim is to guide the selection of appropriate approaches for research and clinical applications, and to highlight opportunities for developing robust, clinically translatable diagnostic tools. Full article

Diffusiophoresis of a liquid metal droplet (LMD) in a cylindrical pore is investigated theoretically in this study. A patched pseudo-spectral method based on Chebyshev polynomials combined with a geometric mapping technique is adopted to solve the resulting governing electrokinetic equations in irregular geometries. Several interesting phenomena are found which provide useful guidelines in practical applications involving liquid metal droplets (LMDs) such as drug delivery. In particular, the severe boundary confinement effect brings about unique features of droplet motion, leading to mobility reversal and a “stagnation phenomenon” where droplets cease to move regardless of their surface charge densities in a narrow cylindrical pore. An overwhelming exterior vortex flow nearly enclosing the entire droplet is found to be responsible for this. This finds various practical applications in droplet microfluidics and drug delivery. For instance, a cylindrical pore or blood vessel may be clogged by a droplet much smaller than its radius. In addition, the “solidification phenomenon”, where all droplets move with identical speed regardless of their viscosities like rigid particles with no interior recirculating vortex flows, is also discovered. The electrokinetic mechanism behind it and its potential applications are discussed. Overall, the geometric configuration considered here is a classic one, with many other possible applications yet to be found by experimental researchers and engineers in the field of colloid industry and operations. Full article

This study applies Computational Fluid Dynamics (CFD) and mathematical modeling to examine uterine and umbilical arterial blood flow during pregnancy, providing a more detailed understanding of hemodynamic changes across gestation. Statistical analysis of Doppler ultrasound data from a large cohort of more than 200 pregnant women (in the second and third trimesters) reveals significant increases in the umbilical arterial peak systolic velocity ($PSV$) between the 22nd and 30th weeks, while uterine artery velocities remain relatively stable, suggesting adaptations in vascular resistance during pregnancy. By combining the Navier–Stokes equations with Doppler ultrasound-derived inlet velocity profiles, we quantify several key fluid dynamics parameters, including time-averaged wall shear stress ($TAWSS$), oscillatory shear index ($OSI$), relative residence time ($RRT$), Reynolds number ($Re$), and Dean number ($De$), evaluating laminar flow stability in the uterine artery and secondary flow patterns in the umbilical artery. Since blood exhibits shear-dependent viscosity and complex rheological behavior, modeling it as a non-Newtonian fluid is essential to accurately capture pulsatile flow dynamics and wall shear stresses in these vessels. Unlike conventional imaging techniques, CFD offers enhanced visualization of blood flow characteristics such as streamlines, velocity distributions, and instantaneous particle motion, providing insights that are not easily captured by Doppler ultrasound alone. Specifically, CFD reveals secondary flow patterns in the umbilical artery, which interact with the primary flow, a phenomenon that is challenging to observe with ultrasound. These findings refine existing hemodynamic models, provide population-specific reference values for clinical assessments, and improve our understanding of the relationship between umbilical arterial flow dynamics and fetal growth restriction, with important implications for maternal and fetal health monitoring. Full article

Microfluidic methods are an important tool for studying the microrheology of blood and the mechanical properties of blood cells—erythrocytes, leukocytes, and platelets. In patients with diabetes, hypertension, obesity, sickle cell anemia, or cerebrovascular or peripheral vascular diseases, hemorheological alterations are commonly observed. These include increased blood viscosity and red blood cell (RBC) aggregation, along with reduced RBC deformability. Such disturbances significantly contribute to impaired microcirculation and microvascular perfusion. In blood vessels, abnormal hemorheological parameters can elevate resistance to blood flow, exert greater mechanical stress on the endothelial wall, and lead to microvascular complications. Among these parameters, erythrocyte deformability is a potential biomarker for diseases including diabetes, malaria, and cancer. This review highlights recent advances in microfluidic technologies for in vitro assays of RBC deformability and aggregation, as well as leukocyte aggregation and adhesion. It summarizes the core principles of microfluidic platforms and the experimental findings related to hemodynamic parameters. The advantages and limitations of each technique are discussed, and future directions for improving these devices are explored. Additionally, some aspects of the modeling of the microrheological properties of blood cells are considered. Overall, the described microfluidic systems represent promising tools for investigating erythrocyte mechanics and leukocyte behavior. Full article