ABSTRACT
OBJECTIVES: Multiple 25(OH)D assays have recently been aligned to improve comparibility. In this study we investigated the performance of these assays using both native single-donor sera with target values certified by a reference method as well as single donor sera from a heterogeneous patient population. DESIGN & METHODS: 25(OH)D levels were measured in twenty reference samples (Ref!25OHD; Labquality, Finland) using five automated methods (Lumipulse, Liaison, Cobas, iSYS and Access) and one aligned ID-XLC-MS/MS method (slope: 1,00; intercept: 0,00; R=0,996). Furthermore, 25(OH)D concentrations measured in 50 pregnant women and 52 random patients using the 5 automated assays were compared to the ID-XLC-MS/MS. In addition, Vitamin D binding protein (DBP) was measured. RESULTS: Most automated assays showed significant differences in 25(OH)D levels measured in reference samples. Slopes varied from 1,00 to 1,33, intercepts from -5.48 to -15,81nmol/L and the R from 0,971 to 0,997. This inaccuracy was even more prominent in a heterogeneous patient population. Slopes varied from 0,75 to 1,35, intercepts from -9.02 to 11,51nmol/L and the R from 0,840 to 0,949. For most assays the deviation in 25(OH)D concentration increased with elevating DBP concentrations suggesting that DBP might be one of the factors contributing to the inaccuracy in currently used automated 25(OH)D methods. CONCLUSIONS: Despite the use of standardized assays, we observed significant differences in 25(OH)D concentrations in some automated methods using reference material obtained from healthy single donor sera. In sera of a patient population this inaccuracy was even worse which is highly concerning as patient samples are being investigated in clinical laboratories.
Subject(s)
Blood Chemical Analysis/instrumentation , Blood Chemical Analysis/methods , Vitamin D/analogs & derivatives , Automation, Laboratory , Female , Humans , Male , Pregnancy , Vitamin D/bloodABSTRACT
OBJECTIVE: Atherosclerosis is associated with increased levels of plasma cytokines and expression of Toll-like receptors (TLRs). Yet, little is known about the potential use of TLR ligand induced cytokine release as a biomarker of coronary artery disease (CAD). In this study, we investigated whether TLR ligand induced cytokine release is associated with atherosclerotic disease severity and its predictive value for future cardiovascular events. METHODS: Blood samples were obtained from 260 patients with stable angina and 15 healthy controls. Cytokine levels of TNFα, IL-8 and IL-6 were measured after 2 h of whole blood stimulation with 10 ng/ml lipopolysaccharide (LPS, TLR4 ligand) and P3C 500 ng/ml (TLR2 ligand). In a subgroup, dose-response curves were created using additional LPS concentrations. RESULTS: LPS induced whole blood release of TNFα and IL-6, but not IL-8, was significantly higher in patients compared to healthy controls. Among CAD patients, TLR responses did hardly differ when associated with the presence of traditional risk factors and atherosclerotic disease severity (number of diseased vessels and coronary stenosis degree). Patients with secondary events during follow-up showed a trend towards an increased TLR response. Furthermore, positive associations were found between CRP levels and TLR-induced TNFα (CRP<2: 2055 pg/ml; CRP>2: 2364 pg/ml) and IL-6 production (CRP<2: 1742 pg/ml; CRP>2: 2250 pg/ml). CONCLUSION: In conclusion, TLR-induced whole blood cytokine release in patients with stable angina indicates the presence of coronary atherosclerosis but does not reflect its severity.
Subject(s)
Angina, Stable/blood , Coronary Artery Disease/blood , Cytokines/metabolism , Leukocytes/cytology , Lipopolysaccharides/blood , Toll-Like Receptors/blood , Aged , Area Under Curve , Atherosclerosis , C-Reactive Protein/metabolism , CD11b Antigen/metabolism , Case-Control Studies , Cytokines/blood , Female , Humans , Male , Middle Aged , Monocytes/cytology , P-Selectin/metabolism , Risk FactorsABSTRACT
AIM: The aim of this study was to compare the effects of 300 mg or 600 mg clopidogrel loading dose, prior to carotid artery stenting (CAS) on the number of transcranial Doppler (TCD)-detected microembolic signals (MES) and to investigate the relationship between the magnitude of platelet reactivity and MES. METHODS: In this prospective randomized, double-blind study, 35 consecutive asymptomatic patients (17.1% females), scheduled for CAS and cardiac surgery were included. The primary endpoint was the number of TCD-detected MES. The secondary endpoints were the absolute magnitude of on-treatment platelet reactivity and the adverse cerebral events. Negative binomial regression to find predictors for sum of single emboli, the student's t-test to assess the association between platelet function tests and randomized dose of 300 mg or 600 mg clopidogrel, and the R2 calculation for the assessment of the association between platelet function tests and embolic load, were used. RESULTS: No statistically significant difference in the number of TCD-detected MES, in the sum of all the single emboli or showers and platelet aggregation measurements between the two groups was observed (aggregometry: 21.7±18.3 versus 23±18%, P=0.8499 and 45.8±17.5 versus 46.5±14.5%, P=0.9003) (verifyNow P2Y12 assay: 231±93 PRU versus 222±86 PRU, P=0.7704). In one patient a transient ischemic attack occurred. CONCLUSION: A loading dose of 300 mg of clopidogrel in combination with aspirin is as effective as 600 mg of clopidogrel in achieving adequate platelet inhibition and preventing periprocedural events in asymptomatic patients undergoing CAS prior to cardiac surgery.
Subject(s)
Cardiac Surgical Procedures , Carotid Stenosis/surgery , Drug-Eluting Stents , Intracranial Embolism/prevention & control , Ischemic Attack, Transient/prevention & control , Ticlopidine/analogs & derivatives , Ultrasonography, Doppler, Transcranial , Aged , Carotid Stenosis/complications , Carotid Stenosis/diagnostic imaging , Clopidogrel , Dose-Response Relationship, Drug , Double-Blind Method , Female , Follow-Up Studies , Heart Diseases/surgery , Humans , Intracranial Embolism/complications , Intracranial Embolism/diagnostic imaging , Ischemic Attack, Transient/diagnostic imaging , Ischemic Attack, Transient/etiology , Male , Platelet Aggregation Inhibitors/administration & dosage , Prognosis , Prospective Studies , Ticlopidine/administration & dosageABSTRACT
Multiple studies have demonstrated the effectiveness of dual or triple antiplatelet therapy with aspirin, clopidogrel and glycoprotein (GP) IIb/IIIa therapy in patients with acute coronary syndromes as well as in patients undergoing coronary stent implantation. In the last few years, it is becoming clear that not all patients receive the full benefits with the current standard dosages of antiplatelet therapy. Specifically, numerous studies have revealed a wide interindividual variability in the response to these antiplatelet agents and, more importantly, both nonresponsiveness as well as a heightened residual platelet reactivity have been linked to the occurrence of adverse cardiovascular events. Therefore, assays that identify those patients with an impaired responsiveness or a heightened platelet reactivity despite dual antiplatelet therapy may contribute to better risk stratification and will probably improve clinical outcome when appropriate action is initiated. Likewise, a considerable number of patients do not achieve the minimal inhibition of aggregation threshold with the current recommended weight-adjusted dosages of GP IIb/IIIa therapy. Identifying and optimizing the absolute degree of platelet inhibition in this subgroup of patients will probably improve clinical outcome. The VerifyNow platform is one of the most user friendly point-of-care platelet function test systems because it produces rapid results at the patient bedside. The purpose of the present paper is to give insight into the principal mechanisms of the VerifyNow system, to discuss its clinical utility for the monitoring of antiplatelet therapy and to discuss the proposed cut-off levels to segregate responders from non-responders for the different types of antiplatelet therapy.