Anticoagulant Activity of Nucleic Acid Nanoparticles (NANPs) Assessed by Thrombin Generation Dynamics on a Fully Automated System.

Rapidly reversible anticoagulant agents have great clinical potential. Oligonucleotide-based anticoagulant agents are uniquely positioned to fill this clinical niche, as they are able to be deactivated through the introduction of the reverse complement oligo. Once the therapeutic and the antidote oligos meet in solution, they are able to undergo isothermal reassociation to form short, inactive, duplexes that are rapidly secreted via filtration by the kidneys. The formation of the duplexes interrupts the structure of the anticoagulant oligo, allowing normal coagulation to be restored. To effectively assess these new anticoagulants, a variety of methods may be employed. The measurement of thrombin generation (TG) reflects the overall capacity of plasma to produce active thrombin and provides a strong contribution to identifying new anticoagulant drugs, including DNA/RNA thrombin binding aptamer carrying fibers which are used through this chapter as an example. Here we describe the TG assessed by Calibrated Automated Thrombogram (CAT) assay in a fully automated system. This method is based on the detection of TG in plasma samples by measuring fluorescent signals released from a quenched fluorogenic thrombin substrate and the subsequent conversion of these signals in TG curves.

Deficiency of coagulation factors is associated with the bleeding diathesis of severe yellow fever.

Yellow fever (YF) is an acute tropical infectious disease caused by an arbovirus and can manifest as a classic hemorrhagic fever. The mechanism of the bleeding diathesis in YF is not well understood. We assessed clinical and laboratory data (including a panel of coagulation tests) from 46 patients with moderate (M) and severe (S) YF admitted to a local hospital between January 2018 and April 2018. Among 46 patients, 34 had SYF of whom 12 (35%) patients died. A total of 21 (45%) patients developed some type of bleeding manifestation and 15 (32%) presented severe bleeding. Patients with SYF had more severe thrombocytopenia (p = 0.001); prolonged activated partial thromboplastin time (aPTT) and thrombin time (TT) (p = 0.03 and p = 0.005, respectively); reduced plasma levels of coagulation factor (F) II (p < 0.01), FIX (p = 0.01), and FX (p = 0.04); and D-dimer levels almost 10 times higher (p < 0.01) when compared with patients with MYF. Patients who died had more bleeding (p = 0.03), more major bleeding (p = 0.03), prolonged international normalized ratio (INR) and aPTT (p = 0.003 and p = 0.002, respectively), as well as lower activity of FII (p = 0.02), FV (p = 0.001), FVII (p = 0.005), FIX (p = 0.01), and protein C (p = 0.01) than the ones who survived. FVIII levels were either normal or increased in all patients studied. Our results suggest that the bleeding diathesis of SYF is associated with the deficiency of coagulation factors produced by the liver. Prolonged INR and aPTT and reduced FII, FV, FVII, FIX, and protein C were associated with death.

Novel Approach to Improve the Identification of the Bleeding Phenotype in Noonan Syndrome and Related RASopathies.

OBJECTIVES: To characterize the bleeding phenotype in Noonan syndrome (NS), to test the utility of following national guidelines in detecting this phenotype, to evaluate thromboelastography (TEG) as a diagnostic tool, and to evaluate the cohort for genotype-phenotype correlations. STUDY DESIGN: Participants with a clinical diagnosis of NS or related RASopathies were enrolled in a cohort study. Study procedures included clinical bleeding assessment, coagulation testing per guidelines, and hematology consultation. TEG was completed in a subset, and genetic testing was conducted for those without a molecular diagnosis. International Society of Haemostasis and Thrombosis Bleeding Assessment Tool scores were calculated with hematology consultation. Bleeding phenotype was defined as abnormal bleeding score. RESULTS: Twenty participants were enrolled; 12 completed clinical and laboratory evaluation, and five of whom met the definition for bleeding phenotype. Four of the five participants with a bleeding phenotype had platelet aggregation defects and at least one additional coagulation defect. TEG was performed in nine participants, four with bleeding phenotype and five without, and results were normal in all cases. No genotype-phenotype correlation was found. CONCLUSION: Five of the 20 participants had a bleeding phenotype identified. Based on available data, we do not recommend incorporating TEG into clinical practice for patients with NS. Platelet aggregation defects were the most common abnormalities, which would not be detected on tier 1 testing of current guidelines; therefore, we propose a new algorithm.

A Clot Twist: Extreme Variation in Coagulotoxicity Mechanisms in Mexican Neotropical Rattlesnake Venoms.

Rattlesnakes are a diverse clade of pit vipers (snake family Viperidae, subfamily Crotalinae) that consists of numerous medically significant species. We used validated in vitro assays measuring venom-induced clotting time and strength of any clots formed in human plasma and fibrinogen to assess the coagulotoxic activity of the four medically relevant Mexican rattlesnake species Crotalus culminatus, C. mictlantecuhtli, C. molossus, and C. tzabcan. We report the first evidence of true procoagulant activity by Neotropical rattlesnake venom in Crotalus culminatus. This species presented a strong ontogenetic coagulotoxicity dichotomy: neonates were strongly procoagulant via Factor X activation, whereas adults were pseudo-procoagulant in that they converted fibrinogen into weak, unstable fibrin clots that rapidly broke down, thereby likely contributing to net anticoagulation through fibrinogen depletion. The other species did not activate clotting factors or display an ontogenetic dichotomy, but depleted fibrinogen levels by cleaving fibrinogen either in a destructive (non-clotting) manner or via a pseudo-procoagulant mechanism. We also assessed the neutralization of these venoms by available antivenom and enzyme-inhibitors to provide knowledge for the design of evidence-based treatment strategies for envenomated patients. One of the most frequently used Mexican antivenoms (Bioclon Antivipmyn®) failed to neutralize the potent procoagulant toxic action of neonate C. culminatus venom, highlighting limitations in snakebite treatment for this species. However, the metalloprotease inhibitor Prinomastat substantially thwarted the procoagulant venom activity, while 2,3-dimercapto-1-propanesulfonic acid (DMPS) was much less effective. These results confirm that venom-induced Factor X activation (a procoagulant action) is driven by metalloproteases, while also suggesting Prinomastat as a more promising potential adjunct treatment than DMPS for this species (with the caveat that in vivo studies are necessary to confirm this potential clinical use). Conversely, the serine protease inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride (AEBSF) inhibited the direct fibrinogen cleaving actions of C. mictlantecuhtli venom, thereby revealing that the pseudo-procoagulant action is driven by kallikrein-type serine proteases. Thus, this differential ontogenetic variation in coagulotoxicity patterns poses intriguing questions. Our results underscore the need for further research into Mexican rattlesnake venom activity, and also highlights potential limitations of current antivenom treatments.

Comparison of different activators of coagulation by turbidity analysis of hereditary dysfibrinogenemia and controls.

Turbidity analysis is widely used as a quantitative technique in hereditary dysfibrinogenemia. We aimed to compare several coagulation triggers in hereditary dysfibrinogenemia and control plasmas. We included 20 patients with hereditary dysfibrinogenemia, 19 with hotspot mutations Aα Arg35His (n = 9), Aα Arg35Cys (n = 2), γ Arg301His (n = 6), γ Arg301Cys (n = 2), and one with Aα Phe27Tyr, and a commercial pooled normal plasma. Fibrin polymerization was activated by bovine or human thrombin or tissue factor (TF), in the presence or absence of tissue type plasminogen activator. The lag time (min), slope (mOD/s), maximum absorbance (MaxAbs, mOD), and area under the curve (AUCp, OD s) were calculated from the fibrin polymerization curves and the time for 50% clot degradation (T50, min), AUCf (OD s) and the overall fibrinolytic potential from fibrinolysis curves. The lag time was significantly shorter and AUC increased in Aα Arg35His patients with bovine thrombin as compared with human thrombin. The MaxAbs and AUCp were significantly higher in γArg301His patients with bovine thrombin compared with human thrombin. Fibrin polymerization parameters of patients' samples were closer to those of control when assessed with TF compared with both human and bovine thrombin. T50 and overall fibrinolytic potential were similar in all samples regardless of the coagulation trigger used, however, with TF the AUCf of Aα Arg35His and γ Arg301His groups were significantly decreased compared with control. Bovine and human thrombin cannot be used equally for studying fibrin polymerization in hotspot hereditary dysfibrinogenemia or control plasmas.

An In Silico Exploration of the Factors That Affect the Precision of the Bethesda Assay.

OBJECTIVES: Despite more than 40 years of experience performing the Bethesda assay (BA), poor intra- and interlaboratory precision remains the biggest laboratory challenge to date. METHODS: The BA procedure was modeled using stochastic simulation techniques to determine the precision of the BA up to dilutions of 1:4,096, to estimate the minimum significant relative change at various inhibitor titers, and to understand the laboratory procedural variables that could significantly affect the performance of the BA at high dilutions. RESULTS: Selecting the lowest dilution tube with a residual activity closest to 25% for calculating the reported Bethesda titer (BT), using a factor activity assay with a coefficient of variation less than or equal to 7.5% in the range of 15% to 50% factor activity level, performing the factor activity measurement in replicates, and minimizing pipette volumetric error resulted in the lowest imprecision in the reported BT. The factor neutralization kinetics of the inhibitor appear to have little impact on the precision of the assay if the incubation time is greater than 90 minutes. CONCLUSIONS: This in silico model will assist future laboratory efforts in standardizing the quantification of specific coagulation factor inhibitors and improving the precision of the reported results.

From Hemophilia to Deep Venous Thrombosis Patient Samples: How to Perform an Easy Coagulometer Validation Process According to Available Guidelines.

Validation protocols for the evaluation of coagulometers are needed to help professionals select the most suitable system for their regular laboratory routines. The objective of this study was to show how high standard protocols for the coagulometer validation process can fit into the daily laboratory routine. For this study, 45 healthy individuals and 112 patient samples were analyzed. From the patient samples, 51 were investigated for deep venous thrombosis, 27 for coagulopathy, 19 for antivitamin K therapy, and 15 for hemophilia. For the assessment, the performance of the 3 coagulometers and 1 point-of-care device was considered. One of the coagulometers was a new acquisition evaluated for precision, linearity, throughput, and carryover in the first moment, and the new coagulometer was then compared with the other well-established equipment in the laboratory. In normal plasma, coefficient of variation was ≤1.8% for total precision in screening tests and ≤3.5% for within-run precision in specific assays. For prothrombin time/international normalized ratio, no significant difference was found when comparing methods. Our study showed how to compare the capacity of a reagent in order to discriminate patients with severe hemophilia from patients with moderated hemophilia, and the κ coefficient agreement was 0.669 (95% confidence interval: 0.3-1.0; P < .001). d-dimer evaluated in patients with deep venous thrombosis and controls showed a 20% discrepancy between the methods. In our experience across Latin America, the number of laboratories that has performed this process is limited. In this study, we demonstrated how to adapt the validation process for the hemostasis laboratory routine to help the professional chose the best and more suitable option.

Thrombin generation test with the calibrated automated thrombogram and anticoagulant activity of Mentha crispa.

: Evaluate the in-vitro effect of Mentha crispa extract on blood coagulation, compare the conventional coagulometric tests with thrombin generation test (TGT), and study the qualitative micromolecular composition of M. crispa. Extract of M. crispa was incubated with plasma and used in the coagulometric tests: prothrombin and activated partial thromboplastin times, fibrinogen, and TGT. A phytochemical prospection was performed to evaluate the chemical composition of this extract. The extract was efficient in prolonging prothrombin time and activated partial thromboplastin time, and reducing fibrinogen levels and TGT parameters, indicating that the extract of M. crispa inhibited the intrinsic and extrinsic pathways of blood coagulation. The results obtained in TGT are in agreement with the results of conventional coagulometric tests and the in-vitro anticoagulant activity of M. crispa suggests that its use by patients using oral anticoagulants deserves caution.

Fresh frozen plasma transfusion in patients with cirrhosis and coagulopathy: Effect on conventional coagulation tests and thrombomodulin-modified thrombin generation.

BACKGROUND & AIMS: The efficacy of fresh frozen plasma (FFP) transfusion in enhancing thrombin generation in patients with cirrhosis and impaired conventional coagulation tests has not been sufficiently explored. Thus, we aimed to assess the effect of FFP transfusion on thrombin generation in these patients. METHODS: Fifty-three consecutive patients receiving a standard dose of FFP to treat bleeding and/or before invasive procedures - if international normalized ratio (INR)/prothrombin time (PT) ratio were ≥1.5 - were prospectively enrolled. The primary endpoint was the amelioration of endogenous thrombin potential (ETP) with thrombomodulin (ETP-TM) after transfusion, which corresponds to the total amount of generated thrombin. INR/PT ratio and activated partial thromboplastin time (aPTT) were also assessed before and after transfusion. RESULTS: FFP enhanced ETP-TM by 5.7%, from 973 (731-1,258) to 1,028 (885-1,343 nM × min; p = 0.019). Before transfusion, evidence of normal or high ETP-TM was found in 94% of patients, even in those with bacterial infections. Only 1 (1.9%) patient had ETP-TM values reverting to the normal range after transfusion. Notably, no patients with low ETP-TM had bleeding. The median decrease in ETP-TM was 8.3% and the mean was 12.8% in 18 (34%) patients after transfusion (from 1,225 [1,071-1,537] to 1,124 [812-1,370] nM × min; p ≤0.0001). Similar responses to FFP transfusion were observed in patients with compensated and acute decompensated cirrhosis, acute-on-chronic liver failure, infection or shock. FFP significantly ameliorated INR and aPTT values (p <0.0001), but in a minority of patients the values were reduced to less than the cut-off point of 1.5. CONCLUSIONS: FFP transfusion enhanced thrombin generation and ameliorated conventional coagulation tests to normal values in a limited number of patients, and slightly decreased thrombin generation in 34% of cases. LAY SUMMARY: Transfusion of fresh frozen plasma in patients with cirrhosis only slightly improves coagulation test values in a limited number of patients and even appears to worsen them in a third of cases. Transfusion for the purpose of preventing or treating bleeding events could cause inherent risks and costs without clear benefits.

Thrombin generation test for evaluating hemostatic effects of Brazilian snake venoms.

Snake venoms as well as their components have been tested worldwide to find new molecules for prophylaxis and treatment of several pathologies or even for diagnostic purposes. It is widely known that snake venoms contain enzymes and non-enzymatic proteins that interfere with hemostasis leading to hemorrhage or even thrombosis. The treatment of snake envenoming and the development of new drugs. The thrombin generation test (TGT) is a highly sensitive tool for investigation of hemostatic changes, overlapping with existing coagulometric techniques. The aim of this study was to use TGT to evaluate in vitro hemostatic changes caused by venom of Brazilian snakes B. jararacussu, B. alternatus, B. moojeni and C. durissus terrificus in a normal pool of platelet-poor plasma, comparing results to those obtained by the classical coagulation assays, at the same concentrations of venom. B. moojeni venom showed to be more hypercoagulable, with a greater ability to activate coagulation, evidenced by increased values of Endogenous Thrombin Potential (ETP), even in the reactions in which the triggering reagent (tissue factor) was not added. On the other hand, the lowest ETP values were observed in plasma incubated with C. durissus terrificus venom. As a new finding of great importance, all venoms at the same concentrations assessed by TGT did not promote changes in a pool of platelet-poor plasma by classic coagulometric assays, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT), whose results were within the reference range. Thus, TGT showed to be more sensitive than the coagulometric assays to evaluate the hemostatic effect of venom components in vitro. Our preliminary results indicate a potential role for TGT in improving the laboratory investigation of hemostatic changes due to snakebite. In addition, elucidation of hemostatic changes induced by different Brazilian snake venoms related to hypocoagulability or hypercoagulability represents an important approach to improving the treatment of snake envenoming and the development of new drugs.

Delayed double reading of whole blood clotting test (WBCT) results at 20 and 30 minutes enhances diagnosis and treatment of viper evenomation

The whole blood clotting test (WBCT) is a simple test of coagulation that is often used in the assessment, diagnosis, and therapeutic monitoring of snakebite patients in sub-Saharan Africa. WBCT requires only a clean glass tube and several milliliters of venous blood and is ideal for use in poorly equipped health centers throughout the rural areas where 95% of snakebites occur. However, questions surrounding the accuracy and reliability of the test remain unanswered due to variations in testing conditions and a lack of comparative research with which to validate them. This is the first study to evaluate WBCT results at both 20-min (WBCT20) and 30-min (WBCT30) reading times in the same group of snakebite patients. Methods In order to define the best reading time, the authors compared the results of serial WBCT evaluation at both 20 and 30 min after collection in 23 patients treated for snake envenomation in Bembèrèkè, northern Benin. Results WBCT results were identical at both reading times in patients without coagulopathy or when coagulation was restored permanently following a single dose of antivenom. Out of 17 patients with coagulopathy, 14 showed discrepancies between WBCT20 and WBCT30 results in at least one pair of serial evaluations. These could be completely contradictory results (e.g. normal clot at WBCT20 and no clot at WBCT30) or a marked difference in the quality of the clot (e.g. no clotting activity at WBCT20 and an unstable partial clot at WBCT30)...

Delayed double reading of whole blood clotting test (WBCT) results at 20 and 30 minutes enhances diagnosis and treatment of viper evenomation

The whole blood clotting test (WBCT) is a simple test of coagulation that is often used in the assessment, diagnosis, and therapeutic monitoring of snakebite patients in sub-Saharan Africa. WBCT requires only a clean glass tube and several milliliters of venous blood and is ideal for use in poorly equipped health centers throughout the rural areas where 95% of snakebites occur. However, questions surrounding the accuracy and reliability of the test remain unanswered due to variations in testing conditions and a lack of comparative research with which to validate them. This is the first study to evaluate WBCT results at both 20-min (WBCT20) and 30-min (WBCT30) reading times in the same group of snakebite patients. Methods In order to define the best reading time, the authors compared the results of serial WBCT evaluation at both 20 and 30 min after collection in 23 patients treated for snake envenomation in Bembèrèkè, northern Benin. Results WBCT results were identical at both reading times in patients without coagulopathy or when coagulation was restored permanently following a single dose of antivenom. Out of 17 patients with coagulopathy, 14 showed discrepancies between WBCT20 and WBCT30 results in at least one pair of serial evaluations. These could be completely contradictory results (e.g. normal clot at WBCT20 and no clot at WBCT30) or a marked difference in the quality of the clot (e.g. no clotting activity at WBCT20 and an unstable partial clot at WBCT30)...(AU)

Delayed double reading of whole blood clotting test (WBCT) results at 20 and 30 minutes enhances diagnosis and treatment of viper evenomation

The whole blood clotting test (WBCT) is a simple test of coagulation that is often used in the assessment, diagnosis, and therapeutic monitoring of snakebite patients in sub-Saharan Africa. WBCT requires only a clean glass tube and several milliliters of venous blood and is ideal for use in poorly equipped health centers throughout the rural areas where 95% of snakebites occur. However, questions surrounding the accuracy and reliability of the test remain unanswered due to variations in testing conditions and a lack of comparative research with which to validate them. This is the first study to evaluate WBCT results at both 20-min (WBCT20) and 30-min (WBCT30) reading times in the same group of snakebite patients. Methods In order to define the best reading time, the authors compared the results of serial WBCT evaluation at both 20 and 30 min after collection in 23 patients treated for snake envenomation in Bembèrèkè, northern Benin. Results WBCT results were identical at both reading times in patients without coagulopathy or when coagulation was restored permanently following a single dose of antivenom. Out of 17 patients with coagulopathy, 14 showed discrepancies between WBCT20 and WBCT30 results in at least one pair of serial evaluations. These could be completely contradictory results (e.g. normal clot at WBCT20 and no clot at WBCT30) or a marked difference in the quality of the clot (e.g. no clotting activity at WBCT20 and an unstable partial clot at WBCT30). WBCT discrepancies were encountered most frequently in three situations: initial normalization of hemostasis following antivenom therapy, detection of a secondary resumption of coagulopathy, or final restoration of hemostasis after a secondary resumption had occurred. Conclusions This study suggests that the WBCT is robust and that a sequential reading should improve the diagnosis and monitoring of venom-induced coagulopathies. It also indicates the possibility of discrepancies in the sensitivity of WBCT20 and WBCT30 for detecting the resolution or reoccurrence of coagulopathy and identifies how these findings, if confirmed, may be used to increase the efficacy and efficiency of antivenom treatment in the field.(AU)

Thromboelastometry versus standard coagulation tests versus restrictive protocol to guide blood transfusion prior to central venous catheterization in cirrhosis: study protocol for a randomized controlled trial.

BACKGROUND: Liver failure patients have traditionally been empirically transfused prior to invasive procedures. Blood transfusion is associated with immunologic and nonimmunologic reactions, increased risk of adverse outcomes and high costs. Scientific evidence supporting empirical transfusion is lacking, and the best approach for blood transfusion prior to invasive procedures in cirrhotic patients has not been established so far. The aim of this study is to compare three transfusion strategies (routine coagulation test-guided - ordinary or restrictive, or thromboelastometry-guided) prior to central venous catheterization in critically ill patients with cirrhosis. METHODS/DESIGN: Design and setting: a double-blinded, parallel-group, single-center, randomized controlled clinical trial in a tertiary private hospital in São Paulo, Brazil. INCLUSION CRITERIA: adults (aged 18 years or older) admitted to the intensive care unit with cirrhosis and an indication for central venous line insertion. Patients will be randomly assigned to three groups for blood transfusion strategy prior to central venous catheterization: standard coagulation tests-based, thromboelastometry-based, or restrictive. The primary efficacy endpoint will be the proportion of patients transfused with any blood product prior to central venous catheterization. The primary safety endpoint will be the incidence of major bleeding. Secondary endpoints will be the proportion of transfusion of fresh frozen plasma, platelets and cryoprecipitate; infused volume of blood products; hemoglobin and hematocrit before and after the procedure; intensive care unit and hospital length of stay; 28-day and hospital mortality; incidence of minor bleeding; transfusion-related adverse reactions; and cost analysis. DISCUSSION: This study will evaluate three strategies to guide blood transfusion prior to central venous line placement in severely ill patients with cirrhosis. We hypothesized that thromboelastometry-based and/or restrictive protocols are safe and would significantly reduce transfusion of blood products in this population, leading to a reduction in costs and transfusion-related adverse reactions. In this manner, this trial will add evidence in favor of reducing empirical transfusion in severely ill patients with coagulopathy. TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02311985 . Retrospectively registered on 3 December 2014.

Coagulation factors, anticoagulant proteins, and plasminogen in Mexican older adults.

INTRODUCTION: Hemostasis protects upon the occurrence of vascular endothelial damage, with involving of different factors. The interaction of these factors in older adults is poorly known, and has been associated with different disorders. Therefore, we determined the activity of coagulation factors (CF), anticoagulant proteins (AP), and plasminogen (Plg), as well as the frequency of deficiencies of these proteins in a population of healthy Mexican older adults (OA). METHODS: CF (I, II, V, VII, VIII, IX, X, and XI y XII), AP [protein C (PC), protein S (PS), and antithrombin (AT)], and Plg were determined from 244 plasma samples of OA using commercial kits in a coagulometer ACL Elite Pro. RESULTS: A total of 139 women and 105 men were under study. They were divided into age range groups (50-59, 60-69, 70-79, and ˃80 years). Activity of CF, AP, and Plg was determined. Frequencies of CF, AP, and Plg activity values were obtained for each age group according to gender. Differences were found between both frequencies for each protein. CONCLUSION: Significant differences were found, so it is recommended to establish reference values (RV) for the activity of fibrinogen and FX by decade and gender, FVII and FXII by gender, FII, FV, FVIII, PC, PS, and Plg by decade, whereas for FIX, FXI, and AT, they are not modified by age or gender, so the RV described for adult Mexican population can be used. It is important to integrate these results into established diagnostic algorithms, which can be taken into account to provide an accurate diagnosis and treatment for patients with suspected hemorrhagic or thrombotic processes, as well as suggest those habits that improve their quality of life, to maintain optimal health and prevent thrombotic and hemorrhagic events.

Amblyomin-X having a Kunitz-type homologous domain, is a noncompetitive inhibitor of FXa and induces anticoagulation in vitro and in vivo.

BACKGROUND: Cancer has long been associated with thrombosis and many of the standard chemotherapeutics used to treat cancer are pro-thrombotic. Thus, the identification of novel selective anticancer drugs that also have antithrombotic properties is of enormous significance. Amblyomin-X is an anticancer protein derived from the salivary glands of the Amblyomma cajennense tick. METHODS: In this work, we determined the inhibition profile of Amblyomin-X and its effect on activated partial thromboplastin time (aPTT) and prothrombin time (PT), using various approaches such as, kinetic analyses, amidolytic assays, SDS-PAGE, and mass spectrometry. RESULTS: Amblyomin-X inhibited factor Xa, prothrombinase and tenase activities. It was hydrolyzed by trypsin and plasmin. MS/MS data of tryptic hydrolysate of Amblyomin-X suggested the presence of Cys(8)-Cys(59) and Cys(19)-Cys(42) but not Cys(34)-Cys(55) disulfide bond. Instead of Cys(34)-Cys(55), two noncanonical Cys(34)-Cys(74) and Cys(55)-Cys(74) disulfide bonds were identified. Furthermore, when Amblyomin-X (1mg/kg) injected in rabbits, it prolonged aPTT and PT. CONCLUSION: Amblyomin-X is a noncompetitive inhibitor (Ki=3.9µM) of factor Xa. It is a substrate for plasmin and trypsin, but not for factor Xa and thrombin. The disulfide Cys(34)-Cys(55) bond probably scrambles with interchain seventh free cysteine residues (Cys(74)) of Amblyomin-X. The prolongation of PT and aPTT is reversible. GENERAL SIGNIFICANCE: In term of anticoagulant property, this is structural and functional characterization of Amblyomin-X. All together, these results and previous findings suggest that Amblyomin-X has a potential to become an anticancer drug with antithrombotic property.

Comparación de la detección foto óptica vs. electromecánica del coágulo / Comparison of mechanical vs. optical clot detection / Comparação da detecção foto-óptica vs. eletromecânica do coágulo

El objetivo de este estudio fue determinar si la detección foto óptica del coágulo es equivalente a la detección electromecánica al realizar el tiempo de protrombina (TP), el tiempo de tromboplastina parcial activado (APTT) y el dosaje de fibrinógeno (FBG). Se estudiaron 258 pacientes consecutivos que concurrieron al laboratorio para realizar estudios de hemostasia. Se utilizaron tres coagulómetros: ACL TOP (foto-óptico) y STArt y Destiny plus como detección electro mecánica. EL TP, APTT y FBG fueron realizados en todos los equipos antes de transcurridas tres horas de la toma de la muestra. Se obtuvo una buena correlación entre los resultados obtenidos con ambos métodos de detección TP (%): (ACL TOP vs. STArt R=0,989; ACL TOP vs. Destiny plus R=0,988), APTT: (ACL TOP vs. STArt R=0,938; ACL TOP vs. Destiny Plus R=0,989), y FBG (ACL TOP vs. STArt R=0,97; ACL TOP vs. Destiny Plus R=0,984). La diferencia de los resultados entre plataformas son menores al error total permitido establecido por los criterios de CLIA (ETa TP y APTT =15% y FBG 20%) en el 95% de las muestras. En los tres coagulómetros evaluados, correctamente mantenidos y calibrados, la detección foto-óptica arrojó resultados equivalentes a la detección electromecánica.

The aim of this study was to determine whether two distinct methodologies based on optical or mechanical clot detection are comparable. Prothrombin time (PT), activated partial thromboplastine time (APTT) and fibrinogen results obtained with mechanical method using two different coagulometers are compared with those obtained by photo optical method within three hours of blood collection. The statistical analysis demonstrated an excellent correlation between optical or mechanical platform for TP, APTT and FBG. TP (%) showed (ACL TOP vs. STArt R=0.989; ACL TOP vs. Destiny Plus R=0.988), APTT: (ACL TOP vs. STArt R=0.938; ACL TOP vs. Destiny Plus R=0.989) y FBG (ACL TOP vs. STArt R=0.97; ACL TOP vs. Destiny Plus 0.984). The differences between optical or mechanical clot detection results are lower than the total error allowable in 95% of the studied samples. To conclude with, the three coagulometers evaluated have maintenance performed and are calibrated according to the international guidelines, and the results obtained with an optical or mechanical clot detection method are equivalent.

O objetivo deste estudo foi determinar se a detecção foto-óptica do coágulo é equivalente à detecção eletromecânica ao realizar o tempo de protrombina (TP), o tempo de tromboplastina parcial ativado (APTT) e a dosagem de fibrinogênio (FBG). Foram estudados 258 pacientes consecutivos que concorreram ao laboratório para realizar estudos de hemostasia. Foram utilizados três coagulómetros: ACL TOP (foto-óptico) e STArt e Destiny plus como detecção eletromecânica. O TP, APTT e FBG foram realizados em todos os equipamentos antes de decorridas três horas da tomada da amostra. Uma boa correlação foi conseguida entre os resultados obtidos com ambos os métodos de detecção TP (%): (ACL TOP vs. STArt R=0,989; ACL TOP vs. Destiny plus R =0,988), APTT: (ACL TOP vs.STArt R=0,938; ACL TOP vs. Destiny Plus R=0,989), e FBG (ACL TOP vs. STArt R=0,97; ACL TOP vs. Destiny Plus R=0,984). A diferença dos resultados entre plataformas é menor ao erro total permitido estabelecido pelos critérios de CLIA (ETa TP e APTT =15% e FBG 20%) em 95% das amostras. Nos três coagulómetros avaliados, corretamente mantidos e calibrados a detecção foto-óptica lança resultados equivalentes à detecção eletromecânica.

Tromboelastometría ROTEM® delta vs. tromboelastografía clásica y pruebas tradicionales de hemostasia / Thromboelastometry ROTEM® delta vs Thromboelastography and classical hemostasis tests / Tromboelastometria ROTEM® delta vs. tromboelastografia clássica y testes tradicionais de hemostasia

La tromboelastometría (TEM) y tromboelastografía (TEG) describen la interacción entre factores de coagulación, fibrinógeno, plaquetas y sistema fibrinolítico en tiempo real, evaluando las características cinéticas y viscoelásticas del coágulo. El objetivo del estudio fue correlacionar parámetros de TEM y TEG, con tiempo de protrombina (TP), tiempo de tromboplastina parcial activado (APTT), fibrinógeno y recuento plaquetario. Se estudió una población comparativa de TEM-TEG de 27 muestras y de TEM-Pruebas clásicas de coagulación de 141 muestras de pacientes con distintas patologías, tratamientos anticoagulantes y procedimientos quirúrgicos. Los TEMogramas fueron: Tromboelastómetro ROTEM® delta (Tem International GmbH) con reactivos INTEM (ácido elágico + Ca+2), EXTEM (factor tisular + Ca+2) y FIBTEM (EXTEM con Inhibidor de plaquetas); TEG: reactivo Cl2Ca, Tromboelastógrafo (D Hellige). Se efectuaron TP (% actividad), APTT (seg) y Fibrinógeno (mg/dL) con reactivos HemosIL (Instrumentation Laboratory) y coagulómetros ACL TOP. Se usó el Test de Pearson (IBM, SPSS 22). Se obtuvieron correlaciones: Muy buenas: a) amplitudes TEM y TEG, r=0,879 y 0,843, p<0,001, para EXTEM e INTEM, b) amplitudes FIBTEM con Fibrinógeno r=0,912, p<0,001, c) tiempos de coagulación (reacción) y de formación del coágulo (amplitud 20 mm), INTEM y TEG r=0.918 y 0,919, p<0,001, d) Lisis máxima EXTEM y TEG r=0,937, p<0,001. Moderadas: a) tiempo formación del coágulo, EXTEM y TEG r=0,782 p<0,001, b) amplitudes con fibrinógeno y plaquetas, r=0,718 y 0,611, p<0,001 para EXTEM, 0,680 y 0,545, p<0,001 para INTEM; c) tiempo de coagulación INTEM y APTT r=0,693, p<0,001. Los parámetros de TEM y TEG correlacionaron muy bien, a excepción del tiempo de coagulación con EXTEM y TEG, dado que utilizan distinto principio para activar coagulación. El análisis de las pruebas clásicas confirmó la alta correlación entre amplitudes del FIBTEM y niveles de fibrinógeno y la mejor correlación entre los tiempos de coagulación del INTEM con APTT que los de EXTEM con TP.

Thromboelastometry (TEM) and thromboelastography (TEG) describe the interaction between coagulation factors, fibrinogen, platelets and fibrinolytic system in real time by the evaluation of the kinetic and viscoelastic characteristics of the clot. The objectives of the study were to correlate TEM with TEG parameters, and with prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen and platelet count. A comparative population of 27 TEM-TEG samples was studied and of TEM-classical coagulation tests of 141 samples from patients with different pathologies, under anticoagulant treatments and surgical procedures. The TEMograms were: Tromboelastometry ROTEM® delta (Tem International GmbH) with INTEM reactants (ellagic acid + Ca2+), EXTEM (tissue factor + Ca2+) and FIBTEM (EXTEM with platelet inhibitor); reactant TEG: Cl2Ca, Tromboelastograph (D Hellige). PT were performed (% activity), APTT (sec) and Fibrinogen (mg/dL) with HemosIL (Instrumentation Laboratory) and ACL TOP coagulometers. The Pearson Test was used (IBM,SPSS 22). The following correlations were obtained: Very good: a) TEM and TEG amplitudes, r=0.879 and 0.843, p<0.001, for EXTEM and INTEM, b) FIBTEM amplitudes with Fibrinogen r=0.912, p<0.001, c) coagulation times (reaction) and clot formation (20 mm amplitude), INTEM and TEG r=0.918 and 0.919, p<0.001, d) Maximum Lysis EXTEM and TEG r=0.937, p<0.001; and Moderate: a) clot formation EXTEM and TEG r=0.782 p<0.001; b) fibrinogen and platelet amplitudes, r=0.718 and 0.611, p<0.001 for EXTEM, 0.680 and 0.545, p<0.001 for INTEM; c) coagulation time INTEM and APTT r=0.693, p<0.001. TEM and TEG parameters correlate very well, except for the coagulation time with EXTEM and TEG, given they use a different principle to activate coagulation. The analysis of the classic tests confirmed the high correlation between FIBTEM amplitudes and the levels of fibrinogen and a better correlation between INTEM coagulation times with APTT than those of EXTEM with TP.

A tromboelastometria (TEM) e tromboelastografia(TEG) descrevem a interação entre fatores de coagulação, fibrinogênio, plaquetas e sistema fibrinolítico em tempo real, avaliando as características cinéticas e viscoelásticas do coágulo. O objetivo do estudo foi correlacionar parâmetros de TEM e TEG, com tempo de protrombina (TP), tempo de tromboplastina parcial ativado (APTT), fibrinogênio e contagem de plaquetas. Foi estudada uma população comparativa de TEM-TEG 27 amostras e de TEM-Testes clássicos de coagulação de 141 amostras de pacientes com diversas patologias, tratamentos anticoagulantes e procedimentos cirúrgicos. Os TEMogramas foram: Tromboelastômetro ROTEM® delta (Tem International GmbH) com reagentes INTEM (ácido elágico + Ca2+), EXTEM (fator tissular + Ca2+) e FIBTEM (EXTEM com Inibidor de plaquetas); TEG: reagente Cl2Ca, Tromboelastógrafo (D Hellige). Foram realizados TP (% atividade), APTT (seg) e Fibrinogênio (mg/dL) com HemosIL (Instrumentation Laboratory) e coagulômetros ACL TOP. Utilizou-se o Teste de Pearson (IBM,SPSS 22). Foram obtidas correlações: Muito boas: a) amplitudes TEM e TEG, r=0,879 e 0,843, p<0,001, para EXTEM e INTEM, b) amplitudes FIBTEM com Fibrinogênio r=0,912, p<0,001, c) tempos de coagulação (reação) e de formação do coágulo (amplitude 20 mm), INTEM e TEG r=0.918 e 0,919, p<0,001, d) Lise máxima EXTEM e TEG r=0,937, p<0,001. Moderadas: a) tempo formação do coágulo, EXTEM e TEG r=0,782 p<0.001, b) amplitudes com fibrinogênio e plaquetas, r=0,718 y 0,611, p<0,001 para EXTEM, 0,680 e 0,545, p<0,001 para INTEM; c) tempo de coagulação INTEM e APTT r=0,693, p<0,001. Os parâmetros de TEM e TEG correlacionaram muito bem, exceto o tempo de coagulação com EXTEM e TEG, devido a que utilizam diferente princípio para ativar coagulação. A análise dos testes clássicos confirmou a alta correlação entre amplitudes do FIBTEM e níveis de fibrinogênio e a melhor correlação entre os tempos de coagulação do INTEM com APTT que os de EXTEM com TP.

Cuantificación del desempeño analítico de los métodos automatizados empleados en el Laboratorio de Hematología del INEN mediante la métrica Sigma / Quantification of the analytical performance of the automated methods used in the Hematology Laboratory of the INEN using the Sigma metric

Introducción: La metodología de gestión de control de calidad Six sigma fue propuesta inicialmente para la industria en 1980. Una década después se implementó en el campo de los servicios médicos. La cuantificación del desempeño de las pruebas de laboratorio empleando la métrica sigma es una ruta ensayada desde el 2000, ha demostrado ser sostenible y aplicable con resultados bastante útiles. Esta metodología implica definir previamente una especificación de la calidad para el proceso cuyo performance se desea analizar. Un valor de sigma 6 o mayor a 6 indica un desempeño excelente en el que la probabilidad de exceder el valor del Error total admisible (TEa) es muy baja; un valor de sigma de 4 a 6 indica buen desempeño; sigma de 3 a 4, regular desempeño y una sigma menor a 2, inaceptable desempeño. Objetivos: Evaluar el desempeño de los métodos automatizados empleados en el laboratorio de hematología del INEN utilizando la métrica Sigma. Evaluar el desempeño de tos métodos automatizados empleados para realizar el Recuento de leucocitos (WBC); Glóbulos rojos (RBC); Plaquetas (PQ), Hemoglobina (HB) y Hematocrito (HCT); en el laboratorio de hematología general del INEN durante el año 2012 al 2013, empleando como indicador la métrica Sigma. Evaluar el desempeño de los métodos automatizados empleados para realizar el tiempo de protrombina (TP); tiempo de tromboplastina parcialmente activada (TTPA); tiempo de trombina (TT); Fibrinógeno y Dímero D en el laboratorio de hematología general del INEN durante el año 2012 al 2013, empleando como indicador la métrica Sigma. Determinar el Error Sistemático Crítico (ESC) a partir del desempeño obtenido para las metodologías automatizadas empleadas en el laboratorio de Hematología general del INEN. Diseño: El presente estudio es de tipo descriptivo y transversal. Lugar: El lugar donde se realizó el presente estudio es el laboratorio de Hematología General del Instituto Nacional de Enfermedades Neoplásicas INEN. Material: Se...

Introduction: Six sigma was initially proposed as a quality control management for the Industry in 1980. A decade later was implemented in the field of medical services. Performance's quantification of laboratory tests using the sigma metric is a tested route since 2000. It has proven to be sustainable and implementable with useful results. This methodology involves predefine a quality specification for the process in study. A sigma value of 6 or more than 6 indicates an excellent performance and its probability of overcome the total error allowable (Tea) is very low. A sigma value from 4 to 6 indicates good performance, sigma from 3 to 4 regular performance, and a sigma value below 2, unacceptable performance. Objectives: Evaluate the performance of automated methods applied in the laboratory of hematology INEN by Sigma metric. Evaluate the performance of automated methods applied to quantify leukocytes (WBC); Red blood cells (RBC); Platelets, Hemoglobin (HB) and Hematocrit (HCT); in the laboratory of general hematology INEN from 2012 to 2013, using the Sigma metric as an indicator. Evaluate the performance of automated methods applied to determine prothrombin time (PT); activated partial thromboplastin time (APTT); thrombin time (TT); Fibrinogen and D-dimer in the laboratory of general hematology INEN from 2012 to 2013, using the Sigma metric as an indicator. Determine the Systematic Error Critical for automated methodologies applied in the laboratory of General Hematology INEN with performance data obtained. Design: This study is descriptive and cross-sectional. Place: The place where this study was performed was laboratory of General Hematology of the National Institute of Neoplasic Diseases INEN. Material: Results of internal control daily were obtained from both hematological automated equipment Sysmex XE 2100 and two coagulometric automated equipment STA compact. Data from external controls (RIQAS) and interlaboratory BIORAD were also collected...