1,721,028 research outputs found
Hemolysis, lipaemia and icterus in specimens for arterial blood gas analysis.
No full textObjective: To assess prevalence of interference from hemolysis, lipaemia, icterus in arterial blood gas analysis (ABG). Design: Serum indices (SI) were assessed in the plasma of ABG samples over a 2-month period. Results: Out of a total of 478 ABG specimens, we identified 17 hemolyzed samples (4%), 52 (11%) with lipaemia, and 63 (13%) with icterus. Conclusion: Test results on a considerable number of ABG specimens might be unreliable due to presence of interference. © 2011 The Canadian Society of Clinical Chemists
The role of epigenetics in the regulation of hemostatic balance
No full textEpigenetics, a term conventionally used to explain the intricate interplay between genes and the environment, is now regarded as the fundament of developmental biology. Several lines of evidence garnered over the past decades suggest that epigenetic alterations, mostly encompassing DNA methylation, histone tail modifications, and generation of microRNAs, play an important, though still incompletely explored, role in both primary and secondary hemostasis. Epigenetic variations may interplay with platelet functions and their responsiveness to antiplatelet drugs, and they may also exert a substantial contribution in modulating the production and release into the bloodstream of proteins involved in blood coagulation and fibrinolysis. This emerging evidence may have substantial biological and clinical implications. An enhanced understanding of posttranscriptional mechanisms would help to clarify some remaining enigmatic issues in primary and secondary hemostasis, which cannot be thoughtfully explained by genetics or biochemistry alone. Increased understanding would also pave the way to developing innovative tests for better assessment of individual risk of bleeding or thrombosis. The accurate recognition of key epigenetic mechanisms in hemostasis would then contribute to identify new putative therapeutic targets, and develop innovative agents that could be helpful for preventing or managing a vast array of hemostasis disturbances
Reference range of hemolysis index in serum and lithium-heparin plasma measured with two analytical platforms in a population of unselected outpatients.
No full textBACKGROUND: The hemolysis index (HI) is now available in several laboratory analyzers, but doubts remain about the thresholds for suppressing test results, the degree of standardization among different instrumentations and the use of different reference ranges in different biological matrices. This study was hence planned to establish the reference ranges of HI in serum and lithium-heparin plasma in a population of unselected outpatients, using two analytical platforms.
MATERIALS AND METHODS: We analyzed the HI in serum and lithium-heparin samples collected from 135 unselected outpatients, and we also defined the relative reference ranges according to Clinical and Laboratory Standards Institute (CLSI) recommendations. Samples were collected in the morning by expert nurses, using straight needle venipuncture. The HI in serum and lithium-heparin plasma was assessed with Roche Cobas c501 and Siemens Dimension Vista 1500.
RESULTS: The median concentration of cell-free hemoglobin was significantly higher in serum than in lithium-heparin plasma when measured with Cobas c501, but not with Dimension Vista 1500. After categorizing values according to cell-free hemoglobin thresholds, the agreement between instruments was 0.75 (p<0.01) for serum and 0.95 (p<0.01) for lithium-heparin plasma. The upper limits calculated according to CLSI document C28-A3 were 0.22g/L for Roche Cobas c501 and 0.25g/L for Siemens Dimension Vista 1500 in serum, whereas they were 0.13g/L for Cobas c501 and 0.10g/L for Dimension Vista 1500 in lithium-heparin plasma.
CONCLUSIONS: According to our data, different thresholds of cell-free hemoglobin should be used between serum and lithium-heparin plasma for monitoring phlebotomy practice
Metformin is associated with low levels of vitamin B12 with no effect on other vitamin levels. A selective action of metformin
No full textBackground and aims: Metformin is frequently used in type 2 diabetes. Long-term treatment is associated with low blood levels of vitamin B12. No studies have evaluated whether metformin affects the blood levels of other vitamins with different mechanisms of intestinal absorption. Thus, the aim of this study was to measure vitamin B12 and other vitamin levels in metformin treated type 2 diabetes patients. Methods and results: In 200 ambulatory patients with type 2 diabetes, vitamins B12, A, B1, B6, B9, C and E were measured. Subjects were divided into those taking and those not taking metformin. Vitamin levels were compared in these two groups. Metformin significantly reduced the levels of vitamin B12 compared to patients not taking the drug (227.1 ± 96.9 vs 325.6 ± 176.8 pmol/L, p < 0.001), without affecting the levels of all other measured vitamins. A deficiency of vitamin B12 was found in 21.1 % of patients. Metformin tripled the risk of vitamin B12 deficiency in the multivariate logistic regression model. Conclusions: To the best of our knowledge, this is the first study that shows a specific effect of metformin in reducing the level of vitamin B12 without affecting other vitamin levels
Analytical evaluation of the novel Lumipulse G BRAHMS procalcitonin immunoassay
Full text linkAbstractObjectivesThis study was designed to evaluate the analytical performance of the novel Lumipulse G1200 BRAHMS procalcitonin (PCT) immunoassay.Design and methodsThis analytical evaluation encompassed the calculation of the limit of blank (LOB), limit of detection (LOD), functional sensitivity, intra- and inter-assay imprecision, confirmation of linearity and a comparison with the Vidas BRAHMS PCT assay.ResultsThe LOB, LOD and functional sensitivity were 0.0010ng/mL, 0.0016ng/mL and 0.008ng/mL, respectively. The total analytical imprecision was found to be 2.1% and the linearity was excellent (r=1.00) in the range of concentrations between 0.006–75.5ng/mL. The correlation coefficient with Vidas BRAHMS PCT was 0.995 and the equation of the Passing and Bablok regression analysis was [Lumipulse G BRAHMS PCT]=0.76×[Vidas BRAHMS PCT]+0.04. The mean overall bias of Lumipulse G BRAHMS PCT versus Vidas BRAHMS PCT was −3.03ng/mL (95% confidence interval [CI]: −4.32 to −1.74ng/mL), whereas the mean bias in samples with PCT concentration between 0–10ng/mL was −0.49ng/mL (95% CI: −0.77 to −0.24ng/mL). The diagnostic agreement was 100% at 0.5ng/mL, 97% at 2.0ng/mL and 95% at 10ng/mL, respectively.ConclusionsThese results attest that Lumipulse G BRAHMS PCT exhibits excellent analytical performance, among the best of the methods currently available on the diagnostic market. However, the significant bias compared to the Vidas BRAHMS PCT suggests that the methods cannot be used interchangeably
pH-dependent prion protein conformation in classical Creutzfeldt-Jakob disease
No full textIn transmissible spongiform encephalopathies, the cellular prion protein (PrP(C)) undergoes a conformational change from a prevailing alpha-helical structure to a beta-sheet-rich, protease-resistant isoform, termed PrP(Sc). PrP(C) has two characteristics: a high affinity for Cu(2+) and a strong pH-dependent conformation. Lines of evidence indicate that PrP(Sc) conformation is dependent on copper and that acidic conditions facilitate the conversion of PrP(C) --> PrP(Sc). In each species, PrP(Sc) exists in multiple conformations, which are associated with different prion strains. In sporadic Creutzfeldt-Jakob disease (sCJD), different biochemical types of PrP(Sc) have been identified according to the size of the protease-resistant fragments, patterns of glycosylation, and the metal-ion occupancy. Based on the site of cleavage produced by proteinase K, we investigated the conformational stability of PrP(Sc) under acidic, neutral, and basic conditions in 42 sCJD subjects. Our study shows that only one type of sCJD PrP(Sc), associated with the classical form, shows a pH-dependent conformation, whereas two other biochemical PrP(Sc) types, detected in distinct sCJD phenotypes, are unaffected by pH variations. This novel approach demonstrates the presence of three types of PrP(Sc) in sCJD
Thrombin generation in different commercial sodium citrate blood tubes
No full textBackground: This study aimed to verify whether blood drawn into six different commercial coagulation tubes generated comparable results of thrombin generation. Methods: Blood was sequentially collected from 20 healthy subjects into different brand and draw volume 3.2% sodium citrate tubes (4.3 mL Sarstedt, 3.0 mL Greiner, 2.7 mL Becton Dickinson, 2.0 mL Kima, 1.8 mL Sarstedt and 1.0 mL Greiner). Thrombin generation was measured in plasma with the fully-automated ST Genesia analyzer using the weakest trigger (STG-BleedScreen). Results: Different values of lag time (LT), time to reach thrombin peak (TP), thrombin peak height (PH) and endogenous thrombin potential (ETP) were commonly found in different tubes. Thrombin generation was the lowest in 4.3 mL Sarstedt tubes and the highest in 1.0 mL Greiner tubes. Other tubes displayed intermediate values. In multiple comparisons, LT was significantly different in 6/15 cases (40%), whilst PH, TP and ETP were significantly different in 14/15 (93%), 13/15 (87%) and 13/15 (87%) cases. The mean percent bias of LT, PH, TP and ETP ranged between -6% and +1%, -27% and +116%, -22% and +8%, and between -18% and +65%. The intra-assay imprecision of LT, PH, TP and ETP was exceeded in 0/15 (0%), 13/15 (87%), 6/15 (40%) and 13/15 (87%) comparisons. The correlation of LT, PH, TP and ETP values in different tubes ranged between 0.718-0.971, 0.570-0.966, 0.725-0.977 and 0.101-0.904. Conclusions: Blood collection for thrombin generation assays requires local standardization using identical tubes for brand and draw volume, and reference ranges calculated according to type of tubes
The concentration of high-sensitivity troponin I, galectin-3 and NT-proBNP substantially increase after a 60-km ultramarathon.
No full textBackground: The leading mechanisms responsible for the most prevalent and serious cardiac injuries include myocardiocyte stretch, myocardiocyte necrosis and cardiac fibrosis, which can now be reliably mirrored by measurement of natriuretic peptides, cardiospecific troponins and galectin-3, respectively. Although a large amount of knowledge has been gathered about the behavior and clinical significance of these biomarkers in patients with cardiac disorders, less information is available on their biology in paraphysiological conditions, including high-intensity endurance exercise. Methods: The study population consisted of 18 trained athletes, who performed a 60-km ultramarathon run. Blood was collected before the run (i.e., "baseline") and immediately after the end of the ultramarathon ("post-marathon") for measurement of serum high-sensitivity troponin I (TnI), NT-proBNP and galectin-3. Results: The concentration of all biomarkers measured in the post-marathon samples was remarkably increased as compared with the values obtained on baseline specimens. In particular, the median increase was 3.3 for TnI, 3.5 for NT-proBNP and 2.4 for galectin-3, respectively. The frequency of values exceeding the diagnostic threshold did not differ at baseline and after the ultramarathon for TnI (6% vs. 25%; p=0.15), instead was significantly increased for NT-proBNP (0% vs. 28%; p=0.016) and galectin-3 (0% vs. 67%; p<0.001). No significant correlation was found among the increase of any of the three biomarkers. Conclusions: The results of this study demonstrate that high-intensity endurance exercise is associated with biochemical abnormalities that may reflect adverse consequences on cardiac structure and biology
Assessment of plasma sample quality on Siemens Atellica COAG 360 System
No full text[no abstract available
Sporadic Creutzfeldt-Jakob disease: prion pathology in medulla oblongata-possible routes of infection and host susceptibility.
Full text linkSporadic Creutzfeldt-Jakob disease (sCJD), the most frequent human prion disorder, is characterized by remarkable phenotypic variability, which is influenced by the conformation of the pathologic prion protein and the methionine/valine polymorphic codon 129 of the prion protein gene. While the etiology of sCJD remains unknown, it has been hypothesized that environmental exposure to prions might occur through conjunctival/mucosal contact, oral ingestion, inhalation, or simultaneous involvement of the olfactory and enteric systems. We studied 21 subjects with definite sCJD to assess neuropathological involvement of the dorsal motor nucleus of the vagus and other medullary nuclei and to evaluate possible associations with codon 129 genotype and prion protein conformation. The present data show that prion protein deposition was detected in medullary nuclei of distinct sCJD subtypes, either valine homozygous or heterozygous at codon 129. These findings suggest that an "environmental exposure" might occur, supporting the hypothesis that external sources of contamination could contribute to sCJD in susceptible hosts. Furthermore, these novel data could shed the light on possible causes of sCJD through a "triple match" hypothesis that identify environmental exposure, host genotype, and direct exposure of specific anatomical regions as possible pathogenetic factors
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