Current concepts of coagulation and fibrinolysis

Exploring the Diversity and Function of Serine Proteases in Toxicofera Reptile Venoms: A Comprehensive Overview

Toxicofera reptile venoms are composed of several toxins, including serine proteases. These proteases are glycosylated enzymes that affect the prey's hemostatic system. Their actions extend across the coagulation cascade, the kallikrein-kinin system, and platelet activation. Despite their specificity for different substrates, these enzymes are homologous across all toxicoferans and display high sequence similarity. The aim of this review is to compile decades of knowledge about venom serine proteases, showing the diversity of biochemically and biophysically characterized enzymes, their structural characteristics, advances in understanding their origin and evolution, as well as methods of obtaining enzymes and their biotechnological applications.

Influence of plasma collection tubes on N-glycome in human blood samples

Background and aims

Quantitative analysis of plasma N-glycome is a promising method for identifying disease biomarkers. This study aimed to investigate the impact of using blood collection tubes with different anticoagulants on plasma N-glycome.

Materials and methods

We used a robust mass spectrometry method to profile plasma N-glycomes in two cohorts of healthy volunteers (cohort 1, n = 16; cohort 2, n = 53). The influence of three commonly used blood collection tubes on fully characterized N-glycomic profiles were explored.

Results

Principal component analysis revealed distinct clustering of blood samples based on the collection tubes. Pairwise comparisons demonstrated significant differences between EDTA and heparin plasma in 55 out of 82 quantified N-glycan traits, and between EDTA and citrate plasma in 62 out of 82 traits. These differences encompassed various N-glycan features, including glycan type, sialylation, galactosylation, fucosylation, and bisection. Trends in N-glycan variations in citrate and heparin plasma were largely consistent compared to EDTA plasma. In correlation analysis (EDTA vs. heparin; EDTA vs. citrate), Pearson's correlation coefficients were consistently higher than 0.7 for the majority of N-glycan traits.

Conclusion

Sample matrix variations impact plasma N-glycome measurements. Caution is crucial when comparing samples from different plasma collection tubes in glycomics projects.

Effects of sample matrix in the measurement of antithrombin by LC-MS: A role for immunocapture

Introduction

The sample matrix composition, which is greatly affected by the type of blood collection tube used during phlebotomy, is of major importance in laboratory testing as it can influence test results. We developed an LC-MRM-MS test to molecularly characterize antithrombin in citrate plasma. The test principle differs greatly from traditional laboratory tests and the influence of varying plasma sample matrices is largely unknown.

Objectives

To identify whether variations in sample matrix affect the LC-MRM-MS test for antithrombin and assess whether sample pre-processing by immunocapture reduces matrix-specific effects.

Methods

Samples (n = 45) originating from four different blood collection tubes (sodium citrate, lithium heparin, K2-EDTA and K2-EDTA with protease inhibitors) were processed directly or after immunocapture. Antithrombin was digested into proteotypic peptides, which were monitored by LC-MRM-MS. Results from lithium heparin and the K2-EDTA matrices were compared to the standard sample matrix, sodium citrate, using Deming regression analysis and repeated measures one-way ANOVA.

Results

Deming regression analysis of directly processed samples revealed slopes deviating >5% from the line of identity for at least six out of 22 peptides in all matrices. Significant differences between all matrices were found upon analysis by ANOVA for at least 10 peptides. Pre-processing by immunocapture led to slopes within 5% of the line of identity for nearly all peptides of the matrices. Furthermore, significant differences between matrices after immunocapture were only observed for four peptides.

Conclusion

Variations in the sample matrix affect the measurement of antithrombin by LC-MRM-MS, but observed effects are greatly reduced upon pre-processing by immunocapture.

Clot activators and anticoagulant additives for blood collection. A critical review on behalf of COLABIOCLI WG-PRE-LATAM

In the clinical laboratory, knowledge of and the correct use of clot activators and anticoagulant additives are critical to preserve and maintain samples in optimal conditions prior to analysis. In 2017, the Latin America Confederation of Clinical Biochemistry (COLABIOCLI) commissioned the Latin American Working Group for Preanalytical Phase (WG-PRE-LATAM) to study preanalytical variability and establish guidelines for preanalytical procedures to be applied by clinical laboratories and health care professionals. The aim of this critical review, on behalf of COLABIOCLI WG-PRE-LATAM, is to provide information to understand the mechanisms of the interactions and reactions that occur between blood and clot activators and anticoagulant additives inside evacuated tubes used for laboratory testing. Clot activators - glass, silica, kaolin, bentonite, and diatomaceous earth - work by surface dependent mechanism whereas extrinsic biomolecules - thrombin, snake venoms, ellagic acid, and thromboplastin - start in vitro coagulation when added to blood. Few manufacturers of evacuated tubes state the type and concentration of clot activators used in their products. With respect to anticoagulant additives, sodium citrate and oxalate complex free calcium and ethylenediaminetetraacetic acid chelates calcium. Heparin potentiates antithrombin and hirudin binds to active thrombin, inactivating the thrombin irreversibly. Blood collection tubes have improved continually over the years, from the glass tubes containing clot activators or anticoagulant additives that were prepared by laboratory personnel to the current standardized evacuated systems that permit more precise blood/additive ratios. Each clot activator and anticoagulant additive demonstrates specific functionality, and both manufacturers of tubes and laboratory professional strive to provide suitable interference-free sample matrices for laboratory testing. Both manufacturers of in vitro diagnostic devices and laboratory professionals need to understand all aspects of venous blood sampling so that they do not underestimate the impact of tube additives on laboratory testing.

Hereditary Blood Coagulation Disorders: Management and Dental Treatment

Patients with hereditary hemostatic disorders, characterized by a tendency to bleeding or thrombosis, constitute a serious challenge in the dental practice. Advances in the medical diagnosis of hemostatic disorders have exposed dental professionals to new patients not amenable to the application of the management protocols associated with other, more well-known, disorders. It is the aim of this paper to review the evidence, to highlight the areas of major concern, and to suggest management regimens for patients with hereditary hemostatic disorders. An extensive review has been made (PubMed, Science Direct, Web of Knowledge, etc.) of literature pertaining to hereditary disorders affecting blood coagulation factors and how they affect the practice of dentistry. Several aspects relating to the care of such patients must be recognized and taken into consideration when dental treatment is planned. Replacement of deficient coagulation factors ensures that safe dental treatment will be carried out. However, the half-life of such coagulation factors requires that dental treatment be specifically planned and adapted to the type of pathology involved.

Current perspectives on laboratory markers for the assessment of cardiovascular disease and myocardial damage

The disruption of the endothelim is a prelude to the evolution of arteriosclerosis. Nitric oxide is critical to endothelial function. The oxidation of low density lipoprotein (LDL) mediated by small dense LDL particles contributes to the development of cardiovascular disease. The multiple effects of homocysteine including its potentiating the binding of lipoprotein(a) (LP(a)) to fibrin and its role in the formation of small dense LDL particles highlights its importance in the evolution of cardiovascular disease and justifies its measurement. Problems in measurement of homocysteine should be kept in perspective. The measurement of release of proteins from the cardiac contractile apparatus such as Troponin I has advantages over conventional measurement of cardiac enzymes and isozymes.

Characterization of the pro-thrombotic state in CAPD patients

PURPOSE

To investigate whether a chronic pro-thrombotic tendency, which may contribute to a high rate of atherothrombotic disease, is present in patients treated for continuous peritoneal dialysis (CAPD), and, if so, what its pattern is. We investigated this issue by jointly exploring all the systems involved, the coagulation and fibrinolytic systems and platelets.

METHODS

Markers of coagulation activation, markers of fibrinolysis activation, and standard fibrinolytic parameters and platelet aggregation induced by different agents were measured in 15 patients treated by CAPD and in 15 matched, healthy controls. All CAPD patients received erythropoietin, were in the stable condition, and did not have acute disease or malignancy.

RESULTS

CAPD patients had substantially (p < 0.001) increased levels of prothrombin fragments F1+2, disclosing a low-grade activation of the coagulation system. D-dimer was also significantly (p < 0.05) increased, whereas the levels of t-PA antigen and activity, PAI antigen and activity, and plasminogen were comparable to controls, suggesting that slight secondary (and not primary) activation of fibrinolysis due to coagulation activation took place. Patients had significantly (p < 0.05) elevated levels of fibrinogen. A study of platelet aggregation (induced by adenosine diphosphate, collagen, and epinephrine) did not show platelet hyperactivity in patients.

CONCLUSIONS

We found that a pro-thrombotic tendency is present in the plasma of CAPD patients. The main reason for a pro-thrombotic state is chronic low-grade activation of the coagulation system and elevated levels of fibrinogen. The fibrinolytic system and platelets seemingly do not contribute to this pro-thrombotic tendency.

Impact of Ultra-Sensitive technology and contemporary therapy on laboratory results

The introduction of ultra-sensitive labels for immunoassays has exposed some of the limitations inherent in them. Thus, for instance a major problem with acridinium esters used, as chemiluminescence label is the formation of the so called "pseudobases" at an alkaline pH, which if not suppressed can affect the rate of the chemiluminescence reaction. Chemiluminescence labels such as luminol can also be problematic when attached to antibodies and small molecules to the extent that the sensitivity of the assay can be reduced by the decrease in the intensity of chemiluminescence. The increased use of molecular methods such as polymerase chain reaction (PCR) and post PCR methods to study mutations have various pittalls, which if unrecognized and uncontrolled can lead to incorrect results and misinterpretation. Patients who are exposed to mouse immunoglobulins through imaging or therapeutic techniques can develop antibodies to mouse immunoglobulins (human anti-mouse antibodies or HAMA) which can be a major problem for non optimized immunoassays using murine monoclonal antibodies. The types of therapy such as anticoagulant used in anticoagulant therapy, blood substitute and drug therapy can impact on the measurements of some of the biochemical and other analytes. One must separate the transient, physiological effects introduced by therapy from long-term biochemical alterations due to disease.