Platelet Function Analyzer Research Articles

Rituximab in lupus anticoagulant hypoprothrombinemia syndrome: A case report.

Lupus anticoagulant hypoprothrombinemia syndrome (LAHPS) is a rare autoimmune condition characterized by acquired prothrombin (FII) deficiency associated with antiphospholipid syndrome (APS) and life-threatening bleeding. We present the case of a 34-year-old woman with heavy menstrual bleeding (HMB), positive Lupus anticoagulant (LA) test, and high titer anticardiolipin antibodies Immunoglobulin G (ACA IgG) and anti-β2 glycoprotein I antibodies IgG (antiB2GPI IgG). Severe iron deficiency anemia necessitated recurrent blood transfusions and intravenous iron infusions from 2018 to 2021. In January 2022, she was admitted to our clinic. Von Willebrand disease screening and platelet function analysis (PFA100) were normal. FII and FIX deficiencies were detected, without factor IX inhibitors. Anti-phosphatidylserine/prothrombin antibodies were confirmed by Padua University lab. To reduce antibody titers and menstrual bleeding, immunosuppressive therapy (Rituximab 375 mg/m2 weekly ×4 weeks) and hormonal therapy (desogestrel 75 mcg/day) were initiated. After 1-year, complete remission of clinical symptoms was achieved, with normalization of FII and FIX values and moderate reduction of aPS/PT titers, especially IgM isotype.

Lipopolysaccharide from Proteus mirabilis Slows Platelet Plug Formation in Human Whole Blood

Platelets are well known for their role in hemostasis. Additionally, platelets play a crucial role in immune and inflammatory responses. Toll-like receptors (TLRs) can mediate bacterial interactions during infection, triggering platelets to initiate an inflammatory response. TLR-4 receptors enable direct interactions between platelets and the bacterial lipopolysaccharide (LPS) endotoxin. The aim of this study was to assess platelet plug formation in response to LPS from Proteus mirabilis. Human whole blood was treated with varying concentrations of LPS over a range of incubation times. Then, platelet plug formation time was measured, under high shear conditions using the platelet function analyzer PFA-100, as aperture closure time (CT). The addition of either 2 or 10 µg/mL of LPS to 80% whole blood significantly prolonged the CTs even in the absence of preincubation (p = 0.028 or p = 0.049, respectively). With added preincubation of LPS with whole blood, the measured CTs were further prolonged. If the preincubation time was set to 35 min, then even the addition of 0.2 µg/mL of LPS resulted in significant CT prolongation (p < 0.001). Taken together, the platelet plug formation in the presence of collagen/ADP is significantly prolonged by the presence of LPS in a concentration and preincubation time-dependent manner. Exposure to P. mirabilis LPS reduces the platelet aggregation response in human whole blood.

Effect of Selected Crystalloid and Colloid Solutions on Coagulation Status Evaluated by Rotational Thromboelastometry and Platelet Function Analyser: An in vitro Study

Introduction: Crystalloid and colloid solutions commonly used in intensive and perioperative care can affect haemocoagulation status. This in vitro study assessed the impact of Plasma-Lyte, albunorm 5%, and Gelaspan 4% solutions on primary and secondary haemostasis using rotational thromboelastometry and platelet function analyser. Methods: In this prospective study, we examined blood samples from 20 healthy volunteers using rotational thromboelastometry and platelet function analyser. Simultaneously, we analysed the blood samples subjected to 10% dilution using Plasma-Lyte, albunorm 5%, and Gelaspan 4% solutions. Results: Compared to controls, Plasma-Lyte shortened EXTEM-CT (p = 0.005) and reduced FIBTEM-MCF (p = 0.017). albunorm 5% prolonged EXTEM-CFT (p = 0.001), decreased EXTEM-alpha (p < 0.001) and MCF in EXTEM, INTEM, and FIBTEM tests (p < 0.001, p = 0.038, p = 0.001, respectively), along with MCE in the PLTEM test (p < 0.001). Gelaspan 4% also prolonged EXTEM-CFT (p < 0.001), decreased EXTEM-alpha (p < 0.001) and MCF in EXTEM, INTEM, and FIBTEM tests (p < 0.001, p < 0.001, p = 0.009, respectively), along with MCE in the PLTEM test (p < 0.001). Gelaspan 4% also reduced EXTEM-CT (p = 0.021). All solution prolonged CT in PFA Col/ADP (p = 0.003 for Plasma-Lyte, p < 0.001 for albunorm and Gelaspan) and albunorm 5% also prolonged CT in Col/Epi (p = 0.003). Conclusion: Plasma-Lyte had the least effect on secondary haemostasis, whereas albunorm 5% had the least effect among colloids. Gelaspan 4% adversely affected the propagation phase of coagulation, maximal strength and elasticity of the coagulum, and the level of functional fibrinogen. All solutions adversely affected platelet function in primary haemostasis, with Plasma-Lyte showing the least effect.

The effect of concurrent clopidogrel and omeprazole administration on clopidogrel metabolism and platelet function in healthy cats.

Some studies in humans show that the concurrent use of clopidogrel and omeprazole decreases plasma clopidogrel active metabolite (CAM) concentrations and clopidogrel antiplatelet effects. Whether this drug interaction occurs in cats is unknown. We hypothesized that administration of clopidogrel with omeprazole would decrease plasma CAM concentrations and decrease clopidogrel antiplatelet effects in healthy cats. Ten domestic cats. In this 2-sequence, 2-period, 2-treatment randomized crossover study, healthy cats were randomly assigned to receive clopidogrel only (18.75 mg PO q24h) or clopidogrel with omeprazole (1 mg/kg PO q12h) for 10 days, followed by a 2-week washout period, and then the opposite treatment for another 10 days. Blood was collected by jugular venipuncture on days 0, 5, and 10. Plasma CAM concentrations were measured using high-performance liquid chromatography-tandem mass spectrometry. Platelet function was evaluated using Plateletworks, Multiplate Analyzer, and Platelet Function Analyzer-100 (PFA-100). Multiplate Analyzer and PFA-100 detected no difference in platelet function between days or treatment groups. Plateletworks detected a significant difference (P < .001) in platelet function from day 0 to 5 and day 0 to 10 in both treatment groups but no difference between treatment groups. Plasma CAM concentrations were significantly lower on day 10 (P < .02) in cats receiving both medications versus clopidogrel only. Concurrent omeprazole and clopidogrel administration was associated with altered pharmacokinetics on day 10, but no difference in pharmacodynamics between the 2 treatment groups. The short-term use of clopidogrel and omeprazole does not seem to alter platelet function significantly.

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

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. Platelet aggregation was induced by ADP in diluted PRP in the presence of 2mM calcium at 23°C. The study included healthy adults (n = 30), healthy children (n = 20), and pediatric patients with suspected or diagnosed platelet function abnormalities (n = 25). The assay parameters were stable for at least 3h after isolation of PRP and were sensitive to plasma dilution in the range of 2-8%. The initial aggregation velocity was significantly reduced in pediatric patients compared with healthy children (p < 0.05). ADP-induced light transmission amplitude was moderately correlated with LaSca amplitude of aggregation in healthy children (p = 0.52, p < 0.05) but not in pediatric patients. We standardized the protocol for platelet aggregation assessment by LaSca and characterized the influence of preanalytical and analytical variables on it.

Comparative study of hemostatic profile between conventional methods and “Sonoclot Coagulation and Platelet Function Analyzer” in patients with septicemia

Abstract: BACKGROUND: Sonoclot Coagulation and Platelet Functional Analyzer (Sonoclot) operating on the principle of micro-viscometry is known to provide comprehensive information on the entire hemostatic process. We hypothesized that performing global hemostasis assessment in patients with sepsis would identify many more patients with altered hemostasis than the conventional tests. OBJECTIVES: We compared the hemostatic status determined by Sonoclot and that by conventional hemostatic tests. METHODS: It was a prospective analytical study conducted for 18 months in a tertiary care hospital. Sixty-one cases of septicemia admitted in the intensive care units were included in the study. RESULTS: Conventional hemostatic tests (platelet count, prothrombin time [PT], international normalized ratio, and activated partial thromboplastin time [APTT]) were compared with the Sonoclot parameters. Conventional hemostatic parameter PT was prolonged in 60.7% and APTT in 31.1%. Overall, 65.6% of the patients had prolonged coagulation on assessment by conventional hemostatic parameters. Sonoclot-derived parameter-activated clotting time was prolonged in 31.1%, indicating 31.1% of cases to have a hypocoagulable state. The clot rate was increased in 93.4% of subjects, indicating 93.4% to have a hypercoagulable state. Thrombocytopenia was seen in 34.4% and thrombocytosis in 10%. Defective platelet function was observed in 92% of the cases in Sonoclot, and all of them had normal platelet counts. This finding was statistically significant. CONCLUSION: Information about hemostatic status identified by Sonoclot is significantly higher and more complete than that identified by conventional coagulation tests in septicemic patients.

Evaluation of the effects and plasma concentration of the platelet inhibitor ticagrelor, after crushed and non-crushed intake, after cardiac arrest and after semi-urgent coronary artery bypass surgery

Background Ticagrelor, used in acute coronary syndrome (ACS), can be administered via nasogastric tube when oral intake is impossible. We investigated platelet inhibition and pharmacokinetics in resuscitated ACS patients and those undergoing semi-urgent coronary artery bypass graft (CABG) surgery. Our study aimed to assess platelet inhibition with use of the Platelet Function Analyser (PFA) and measured plasma concentrations of ticagrelor and its active metabolite in these ACS patients. Methods We included resuscitated cardiac arrest patients (STEMI/NSTEMI) and semi-urgent CABG patients. Crushed ticagrelor tablets were administered using a nasogastric tube. PFA closure time (CT) was determined with CT longer than 113 s as reference range. Plasma concentrations of ticagrelor and its active metabolite were measured after protein precipitation, by using liquid chromatography with mass spectrometry detection. Results In 20 resuscitated patients, 89% showed platelet inhibition at 24 h and 92% at day 4. For semi-urgent CABG patients, 85% exhibited platelet inhibition at 24 h and 84% at day 4. For ticagrelor in resuscitated patients, the median time to peak plasma concentration (Tmax) was 100 h [8; 100] for a median maximal concentration (Cmax) of 615.5 ng/mL [217.5; 1385.0]. For AR-C124910XX median Tmax was 100 h [8; 100] for a Cmax of 131.0 ng/mL [52.1; 177.7]. Among 20 patients undergoing semi-urgent CABG, Tmax for ticagrelor was 100 h [100; 100] for a median Cmax of 857.0 ng/ml [496.8; 1157.5]. For AR-C124910XX, median Tmax was 100 h [43; 100] for a Cmax of 251.0 ng/ml [173.0; 396.5]. Conclusion Crushed ticagrelor via nasogastric tube achieved targeted platelet inhibition. Pharmacokinetics aligned with previous studies. EudraCT number: 2013-004191-35; Study protocol code: AGO/2013/011; EC/2014/1061; ClinicalTrial.gov identifier: NCT02341729

Platelet aggregation response to cyclooxygenase inhibition and thromboxane receptor antagonism using impedance aggregometry: A pilot study.

Impedance aggregometry is an alternative to light transmission aggregometry that allows analysis of platelet function in whole blood samples. We hypothesized (1) impedance aggregometry would produce repeatable results, (2) inhibition of cyclooxygenase with aspirin would attenuate aggregation responses to collagen and abolish the aggregation response to arachidonic acid (AA), and (3) thromboxane receptor antagonism (terutroban) would attenuate the aggregation response to AA. Venous blood was obtained from 11 participants three times separated by at least 2 weeks. One sample followed 7-day-aspirin intervention (81 mg once daily; ASA), the others no intervention (control). Aggregation was induced using 1 μg/mL collagen ([col 1]), 5 μg/mL collagen ([col 5]), and 50 mM AA via impedance aggregometry to determine total aggregation (AUC) analyzed for intra-test repeatability, inter-test repeatability, intervention (ASA or control), and incubation (saline or terutroban). [col 1] showed high intra-test (p ≤ 0.03 visit 1 and 2) and inter-test repeatability (p < 0.01). [col 5] and AA showed intra- ([col 5] p < 0.01 visit 1 and 2; AA p < 0.001 visit 1 and 2) but not inter-test repeatability ([col 5] p = 0.48; AA p = 0.06). ASA attenuated AUC responses to [col 1] (p < 0.01), [col 5] (p = 0.03), and AA (p < 0.01). Terutroban attenuated AUC in response to AA (p < 0.01). [col 1] shows sufficient repeatability for longitudinal investigations of platelet function. [col 5] and AA may be used to investigate mechanisms of platelet function and metabolism at a single time point.

Sensitivity and specificity of strategies to identify patients with hemostasis abnormalities leading to an increased risk of bleeding before scheduled intervention: the Hemorisk study

BackgroundPreoperative identification of patients with hemostasis abnormalities leading to an increased bleeding risk is based on routine hemostasis tests: prothrombin time (PT), activated partial thromboplastin time (APTT), and platelet count. Because of their low predictive performance, guidelines recommend replacing them with structured bleeding risk questionnaires, but none is validated in this population. ObjectivesTo assess the diagnostic accuracy of 3 strategies, performed at the preanesthesia visit before scheduled interventions, and to identify patients with hemostasis abnormalities leading to an increased bleeding risk MethodsA multicenter study was performed in 7 French academic hospitals, involving patients scheduled for surgical intervention, without antiplatelet/anticoagulant treatment. The 3 strategies consisted of 1-a structured screening questionnaire; 2-PT, APTT, and platelet count ordered in selected patients; and 3-systematic PT, APTT, and platelet count. The reference standard comprised von Willebrand factor activity/antigen, factor (F)VIII, FIX, FXI, platelet function analyzer, and, when required, FII, FV, FX, and FVII and hemostasis consultation. ResultsEighteen (1.2%) of 1484 patients had a hemostasis abnormality leading to an increased bleeding risk according to reference standard. In the overall cohort, sensitivity of the questionnaire-based strategy was 50% (95% CI, 26%-74%; specificity, 87% [95% CI, 85%-88%]); sensitivity was 0% (95% CI, 0%-41%) in men vs 82% (95% CI, 48%-98%) in women. For selective routine tests, sensitivity was 33% (95% CI, 13%-59%) and specificity 97% (95% CI, 96%-98%). Corresponding values for systematic routine tests were 44% (95% CI, 22%-69%) and 93% (95% CI, 91%-94%). ConclusionSensitivity was low for all 3 strategies investigated. The structured screening questionnaire had clinically acceptable diagnostic accuracy only in women.

An in vitro study of coagulation evaluation in obstetric hemorrhage for pregnancy-induced hypertension with coagulation and platelet function analyzer

ABSTRACT This study aimed to establish in vitro hemodilution and resupplementation assays for obstetric hemorrhage in pregnancy-induced hypertension (PIH) and to monitor the coagulation function dynamically using a coagulation and platelet function analyzer. Forty-seven singleton pregnant women were divided into normal (n = 24) and PIH (n = 23) groups. Peripheral blood samples were used to construct the assays, and the activated clotting time (ACT), clotting rate (CR), and platelet function index (PF) were measured. The results showed that the baseline ACT was higher in the PIH group (p < 0.01). Hemodilution assays showed decreased ACT and increased CR and PF, with ACT changes significantly lower in the PIH group (p < 0.05). CR changed most in both groups at lower dilution ratios (35% to 50%), while ACT changed most at a higher dilution ratio (75%). In the resupplementation assay, ACT exhibited the most significant response. The analyzer effectively detected differences between pregnant women with and without PIH. Thus, we need to pay more attention to the changes of ACT in the actual clinical application to assess the coagulation status of parturients.

Evaluation of coagulation and platelet activation state and function in heartworm-infected dogs.

Enhanced platelet responses have been demonstrated in heartworm-infected (HWI) dogs; however, the cause and clinical implications of altered platelet function have not been fully elucidated. This study evaluated platelet function in HWI dogs. Anticoagulated whole blood collected from eight HWI and eight uninfected dogs was evaluated using turbidometric platelet aggregometry, a platelet function analyzer (PFA-100), a total thrombus analysis system (T-TAS), tissue factor-activated and tissue plasminogen activator modified thromboelastography (TF- and tPA-TEG), CBC, von Willebrand Factor activity, and fibrinogen concentrations. Platelet activation state and the presence of reticulated platelets were assessed via flow cytometric expression of P-selection (CD-62P) and thiazole orange staining. Platelet aggregation responses to adenosine diphosphate (ADP, 10 μM) or collagen (20 μg/mL), PFA-100 closure times, and T-TAS occlusion times did not differ between groups. TEG values TF-R, tPA-R, TF-K, and TF-LY60 were decreased (P = .025, P = .047, P = .038, P = .025) and TF-MA, tPA-MA, TF-G, tPA-G and TF-alpha angle were increased (P < .04) in HWI dogs. HWI dogs had higher fibrinogen concentrations (465.6 ± 161 mg/dL vs 284.5 ± 38 mg/dL, P = .008) and eosinophil counts (0.686 ± 0.27 × 103/μL vs 0.267 ± 0.20 × 103/μL, P = .003). There was no difference in hematocrit, activation state, or percent of reticulated platelets. Non-activated reticulated platelets exhibited higher CD62P expression compared with mature platelets. Chronic canine heartworm disease was accompanied by hypercoagulability, hyperfibrinogenemia, and decreased fibrinolysis. Enhanced platelet activation was not identified in this group of HWI dogs.

Microfluidic System-Based Quantitative Analysis of Platelet Function through Speckle Size Measurement.

Platelets play essential roles in the formation of blood clots by clumping with coagulation factors at the site of vascular injury to stop bleeding; therefore, a reduction in the platelet number or disorder in their function causes bleeding risk. In our research, we developed a method to assess platelet aggregation using an optical approach within a microfluidic chip's channel by evaluating the size of laser speckles. These speckles, associated with slowed blood flow in the microfluidic channel, had a baseline size of 28.54 ± 0.72 µm in whole blood. Removing platelets from the sample led to a notable decrease in speckle size to 27.04 ± 1.23 µm. Moreover, the addition of an ADP-containing agonist, which activates platelets, resulted in an increased speckle size of 32.89 ± 1.69 µm. This finding may provide a simple optical method via microfluidics that could be utilized to assess platelet functionality in diagnosing bleeding disorders and potentially in monitoring therapies that target platelets.

Abstract 140: Exploring Protein Kinase C Theta (PKCθ) Signaling In The Generation Of Procoagulant Platelet: Insights From Phosphoproteomics And Systems Analysis

Background: Platelet activation plays a pivotal role in physiological hemostasis and thrombosis. Protein Kinase C theta (PKCθ) isoforms exert significant regulatory influence on platelet activation. While specific PKC family members have well-defined roles in platelet function, the roles of PKCθ remain less explored. Objectives: To determine mechanisms of PKCθ signaling that orchestrate procoagulant platelet generation. Methods: Platelets were prepared from healthy human donors for ex vivo experiments. Platelet signaling and function were studied following stimulation with GPVI agonist crosslinked collagen-related peptide (CRP-XL). To investigate PKCθ inhibition mechanisms in platelets, small molecule inhibitors targeting the PKCθ (CC-90005 and C20) were employed. Results: From phosphoproteomics, we noted prominent phosphorylation on the C-terminus PKCθ at Ser685. Pretreatment of platelets with inhibitors specific PKC isoforms revealed that PKCα/β, PKCθ, and PKCΔ activities determine PKCθ Ser685 phosphorylation. From the PKC Inhibitors Activity Curves, we noted a robust and selective inhibitory impact of CC-90005 on PKCθ, with specificity surpassing that of C20. Parallel platelet function analyses revealed that inhibiting PKCθ had minimal impact on platelet spreading and aggregation. However, PKCθ inhibition in the presence of Ca 2+ upregulated platelet phosphatidylserine (PS) exposure, as measured by flow cytometry. This was accompanied by an increase in platelet procoagulant activity, where PKCθ inhibition reduced the lag time for fibrin formation. Furthermore, fluorescence microscopy also found that PKCθ inhibition significantly augmented the proportion of procoagulant platelets and microparticles. Additionally, compared to the control group, the use of cyclosporin A (CsA) reduced the production of procoagulant platelets, but the addition of CC-90005 or C20 rescued this phenomenon, with signal intensity surpassing that of the control group. Conclusions: Our study proposes a model wherein PKCΔ and PKCα/β activities induce the phosphorylation of PKCθ at S685, influencing mitochondrial calcium signaling and supporting procoagulant platelet generation.

Platelet activity, coagulation, and fibrinolysis in long-term users of anabolic-androgenic steroids compared to strength-trained athletes

IntroductionUse of anabolic-androgenic steroids (AAS) is associated with adverse cardiovascular (CV) effects, including potential prothrombotic effects. This study aimed to assess platelet activation and aggregation, coagulation, and fibrinolysis, in long-term AAS users compared to non-using strength-trained athletes. Materials and methodsThirty-seven strength-trained men using AAS were compared to seventeen non-using professional strength-trained athletes at similar age (median 33 years). AAS use was verified by blood and urine analyses. Platelet Function Analyzer 100 (PFA-100) and whole blood impedance aggregometry with thrombin, arachidonic acid, and ADP as agonists, were performed to evaluate platelet aggregation. ELISA methods were used for markers of platelet activation. Fibrinogen, D-dimer, the coagulation inhibitors protein S and C activity, and antithrombin were measured by routine. Fibrinolysis was evaluated by Plasminogen Activator Inhibitor-1 (PAI-1) activity. ResultsThere were no significant differences in platelet aggregation between the two groups. Von Willebrand factor was lower among the AAS users (p < 0.01), and P-Selectin was slightly higher (p = 0.05), whereas CD40 Ligand, β-thromboglobulin, and thrombospondin did not differ significantly. No differences were found in the assessed coagulation inhibitors. Higher D-dimer levels (p < 0.01) and lower PAI-1 activity (p < 0.01) were found among the AAS users. ConclusionsThe investigated long-term users of AAS did not exhibit elevated platelet activity compared to strength-trained non-using athletes. However, AAS use was associated with higher D-dimer levels and lower PAI-1 activity. These findings suggest that any prothrombotic effect of long-term AAS use may predominantly involve other aspects of the hemostatic system than blood platelets.

Managing Clopidogrel Resistance in Neurointervention: Surveying Current Approaches

Background Because of the variability in patient responses to clopidogrel and to reduce the risk of thromboembolic complications, adjusting the antiplatelet regimen based on platelet function testing has become a widespread practice in neurointervention. We aimed to explore current patterns related to this practice. Methods We conducted a survey targeting neurointerventionalists, comprising multiple‐choice questions and opportunities for free‐text responses when necessary. The survey was distributed via a professional society distribution list (the Society of Vascular and Interventional Neurology ) and 2 consortium emailing lists (WovenEndoBridge and Neurointerventional Research Consortia). The data obtained from the responses were analyzed using descriptive statistics. Results A total of 133 neurointerventionalists, representing 79 institutions within 27 countries, responded to the survey. A total of 62% of respondents tested for clopidogrel resistance before any neurovascular stent placements. A total of 80% used VerifyNow point‐of‐care P2Y12 assay; other assays included multiplate analyzer, platelet function analyzer, and CYP2C19 genotype assay. Respondents reported 25 different therapeutic thresholds, with the P2Y12 reaction unit range between 60 and 180 most commonly used (16.4%). A total of 61% reported they would switch to ticagrelor in the case of persistent resistance. On the other hand, when patients are supratherapeutic, 48% did not make any changes, whereas 42% reduced clopidogrel dose. Finally, 93% opined that a well‐established protocol for management of clopidogrel resistance was needed. Conclusions Neurointerventional practice patterns around clopidogrel resistance remain heterogeneous. Our results underscore the need for evidence‐based guidance on the management of clopidogrel resistance in neurointervention.

ISTH bleeding assessment tool and platelet function analyzer in children with mild inherited platelet function disorders.

To evaluate the diagnostic performance of platelet function analyzer (PFA) and The International Society on Thrombosis and Hemostasis bleeding-assessment-tool (ISTH-BAT) in detecting mild inherited platelet function disorders (IPFDs) in children with suspected bleeding disorders. Prospective single-center diagnostic study including consecutive patients <18 years with suspected bleeding disorder and performing a standardized workup for platelet function defects including ISTH-BAT, PFA, platelet aggregation testing, blood smear-based immunofluorescence, and next-generation sequencing-based genetic screening for IPFDs. We studied 97 patients, of which 34 von Willebrand disease (VWD, 22 type-1, 11 type-2), 29 IPFDs (including delta-/alpha-storage pool disease, Glanzmann thrombasthenia, Hermansky-Pudlak syndrome) and 34 with no diagnosis. In a model combining PFA-adenosine diphosphate (ADP), PFA-epinephrine (EPI), and ISTH-BAT overall performance to diagnose IPFDs was low with area under the curves of 0.56 (95% CI 0.44, 0.69) compared with 0.84 (95% CI 0.76, 0.92) for VWD. Correlation of PFA-EPI/-ADP and ISTH-BAT was low with 0.25/0.39 Spearman's correlation coefficients. PFA were significantly prolonged in patients with VWD and Glanzmann thrombasthenia. ISTH-BAT-scores were only positive in severe bleeding disorders, but not in children with mild IPFDs or VWD. Neither ISTH-BAT nor PFA or the combination of both help diagnosing mild IPFDs in children. PFA is suited to exclude severe IPFDs or VWD and is in this regard superior to ISTH-BAT in children.

Assessment of Aspirin and Clopidogrel Resistance in Patients Undergoing Cardiovascular Surgery: A Single-Center Cross-Sectional Study

We aimed to investigate antiplatelet drug resistance utilizing light transmission-lumiaggregometry (LT-LA) and the Platelet Function Analyzer-100 (PFA-100) in patients undergoing cardiovascular surgery. The study included 60 patients diagnosed with stable coronary artery disease and peripheral vascular diseases that required surgery. Participants were divided into three groups: patients receiving aspirin (ASA) (n=21), patients receiving clopidogrel (CLO) (n=19), and patients receiving dual therapy (ASA+CLO) (n=20). Aggregation and secretion tests by LT-LA and closure time by the PFA-100 were used to measure antiplatelet drug resistance. Based on the adenosine diphosphate (ADP)-induced aggregation test, 43% of patients were resistant to ASA, 22% to CLO, and 15% to dual therapy. Diabetes, hypertension, and hyperlipidemia were the most commonly identified comorbid disorders. In patients with comorbid risk factors, the median value of platelet aggregation response to ADP was significantly higher in the ASA group than in the CLO and dual therapy groups (p=0.0001). In patients receiving ASA monotherapy, the maximum amplitude of aggregation response to platelet agonists was ≥70% in 43% of patients for ADP and 28% for collagen by LT-LA. Elevated ADP (≥0.29 nmol) and collagen (≥0.41 nmol)-induced adenosine triphosphate release were found by LT-LA in 66% of patients utilizing an ADP agonist and 80% of patients using a collagen agonist undergoing ASA therapy. Closure times obtained with the PFA-100 were normal in 28% of patients using collagen-ADP cartridges and 62% of patients using collagen-epinephrine (CEPI) cartridges who received ASA. Recurrent thrombosis and bleeding were observed in 12 (20%) patients with cardiovascular disease. Three of these individuals (25%) showed ASA resistance with normal responses to ADP-induced aggregation (≥70%) and secretion (≥0.29 nmol), as well as normal CEPI closure times. Our findings suggest that antiplatelet drug monitoring by LT-LA and PFA-100 may be useful for high-risk and complicated cardiovascular patients.

Integrated microfluidic multiple electrode aggregometry for point-of-care platelet function analysis.

Point-of-care (POC) platelet function analysis can enable timely and precise management of bleeding and clotting in emergency rooms, operation rooms and intensive care units. However, POC platelet testing is currently not commonly performed, due to the complexity of sample preparation and limitations of existing technologies. Here, we report the development of an integrated microfluidic multiple electrode aggregometry (μMEA) sensor which uses multi-frequency impedance measurement of an embedded microelectrode array to perform platelet aggregometry directly from whole blood, sensing and measuring platelet activation in a label-free manner and without requiring any additional sample preparation. Additionally, the sensor incorporates blood flow during the assay to account for physiological flow and shear conditions. We show that the impedance signal from the sensor can be used to accurately detect and quantify platelet aggregation in a label-free manner, which was further validated by simultaneous fluorometric measurement and visualization of platelet aggregation. Further, we optimized the sensitivity and repeatability of the sensor using its frequency response and demonstrated that the sensor could be used to characterize drug dose-response in antiplatelet therapy with a frequency-tunable dynamic range. We also demonstrate that the sensor provides high sensitivity to perform platelet aggregometry under thrombocytopenic or low platelet count conditions. The μMEA sensor could thus enable POC platelet function analysis across several clinical applications.

The effects of ambient particulate matter air pollution on platelets and hemostasis.

Elevated ambient pollution exposure is potentially linked to thromboembolism. However, the mechanisms by which particulate matter (PM) interferes with the balance of hemostatic system remain unclear. This study investigates PM-mediated hemostatic changes in individuals across unique seasonal variations of ambient pollution. This prospective study was conducted between February and July 2020 during alterations in ambient pollution in Chiang Mai, Thailand. Blood tests from 30 healthy subjects were assessed at four-week intervals, four times in total. Various coagulation tests, including prothrombin time (PT), activated partial thromboplastin time (aPTT), von Willebrand factor (vWF), platelet count, and platelet functions, were evaluated. A mixed-effects model was used to analyze the impact of high PM2.5 and PM10 on hemostatic parameters. Thirty male subjects with mean age of 38.9 ± 8.2 years, were included. High levels of PM2.5 and PM10 were significantly associated with PT shortening, with no such effect observed in aPTT. PM2.5 and PM10 values also positively correlated with vWF function, while vWF antigen levels remained unchanged. Soluble P-selectin showed a strong positive association with PM2.5 and PM10 levels. Platelet function analysis revealed no correlation with PM values. Short-term exposure to elevated PM2.5 and PM10 concentrations was linked to shortened PT and enhanced vWF function in healthy individuals. Exploring the impact of these changes on clinically relevant thrombosis is crucial. Additional studies on the pathogenesis of pollution-related thrombosis are warranted for maintaining good health.

The Influence of Caramel Carbon Quantum Dots and Caramel on Platelet Aggregation, Protein Glycation and Lipid Peroxidation.

Caramel, defined as a coloring agent and as an antioxidant, is used in several kinds of food products and is consumed by many people in different amounts. In our research we showed that the caramelization of sucrose under special conditions leads to the formation of carbon quantum dots (CQDs). So, it makes sense that humans also consume this type of CQDs, and it is theoretically possible for these particles to affect the body. Despite an increasing number of studies describing different types of CQDs, their biosafety is still not clearly understood. In our in vitro research, we examined the effects on platelet aggregation, protein glycation and lipid peroxidation of CQDs and caramel formed from a 20% sucrose solution. In vitro aggregation tests were conducted using freshly collected whole rat blood in a multiplate platelet function analyzer and measurer of electric impedance. The cytotoxic effect of the tested solutions on blood platelets was evaluated based on the release of lactate dehydrogenase. The formation of glycated bovine serum albumin was measured as fluorescence intensity and fructosamine level. The reducing power of the solutions was determined in adipose tissue, and their effect on lipid peroxidation in adipose tissue in vitro was also assessed. By measuring the intensity of hemolysis after incubation in solutions with red blood cell, we assessed their influence on the integration of the red blood cell membrane. All tests were performed in comparison with glucose and fructose and other frequently used sweeteners, such as erythritol and xylitol. Our study showed that caramel and CQDs formed from caramel may influence the glycation process and integrity of the red blood cell membrane, but unlike glucose and fructose, they decrease lipid peroxidation and may reduce Fe (III). Additionally, it is unlikely that they affect platelet aggregation. Compared to glucose and fructose, they may be safer for patients with metabolic disorders; however, further research is needed on the safety and biological activity of caramel and CQD.