Monitoring of Argatroban in Critically Ill Patients: A Prospective Study Comparing Activated Partial Thromboplastin Time, Point-of-Care Viscoelastic Testing with Ecarin Clotting Time and Diluted Thrombin Time to Mass Spectrometry

BACKGROUND

The direct thrombin inhibitor argatroban is indicated for the treatment of heparin-induced thrombocytopenia II, but it is also used off-label to treat critically ill patients presenting with heparin resistance, severe antithrombin deficiency, or hypercoagulability. Direct drug monitoring is not routinely available, and argatroban dosing is mainly based on global coagulation assays such as activated partial thromboplastin time (PTT) or diluted thrombin time (TT), both of which have limitations in patients with hypercoagulability.

METHODS

Blood samples were obtained from critically ill patients treated with argatroban. Activated PTT and diluted TT were measured with a STA R Max3 analyzer (STAGO Deutschland GmbH, Germany) using an argatroban-calibrated kit. Ecarin clotting time was measured using a point-of-care viscoelastic test device. Liquid chromatography with tandem mass spectrometry was performed using a reversed-phase column, a solvent gradient, and an API4000 mass spectrometer with electrospray. Correlation was described using Pearson correlation coefficient r and Bayesian multilevel regression to estimate relationships between outcomes and covariates.

RESULTS

From June 2021 to March 2022, 205 blood samples from 22 patients were analyzed, allowing for 195 activated PTT-liquid chromatography with tandem mass spectrometry comparisons, 153 ecarin clotting time-liquid chromatography with tandem mass spectrometry comparison, and 105 diluted TT-liquid chromatography with tandem mass spectrometry comparisons. Compared to liquid chromatography with tandem mass spectrometry, performance of argatroban quantification was best for diluted TT (r = 0.91), followed by ecarin clotting time (r = 0.58) and activated PTT (r = 0.48). Regression analysis revealed that patients with sepsis were more prone to argatroban overdosing (coefficient, 4.194; 95% credible interval, 2.220 to 6.792).

CONCLUSIONS

Although activated PTT monitoring of argatroban is the most commonly used test, in critically ill patients, diluted TT provides more precise measurements. Alternately, point-of-care viscoelastic ecarin clotting time also provides guidance for argatroban dosing to identify overdosing if available. The data also suggested that patients with sepsis are at greater risk for argatroban overdosing.

EDITOR’S PERSPECTIVE

[Analysis of failure causes and countermeasures of automatic coagulation analyzer detection of thrombin time]

To study the failure alarm information displayed on the automatic coagulation analyzer (coagulation method) of thrombin time (TT), and formulate the coping strategies combined with clinical information. Methods: A total of 233 failed TT blood samples [132 males, 101 females, with a median age of 73 (66, 79) years] were selected from 21 359 inpatients in Peking University First Hospital from January to June 2021. The statistical analysis was made and the failure causes and solutions were summarized according to the coagulation curve and the error codes displayed on the coagulation instrument, in combination with the clinical information, sample characteristics, medication status and other reasons. Meanwhile, a total of 96 TT detection failed lipid blood samples [56 males, 40 females, with a median age of 72 (65, 79) years] were analyzed from the inpatients in Peking University First Hospital from July to November 2021. TT results were obtained by artificial coagulation curve interpretation method, magnetic bead method and high-speed centrifugal re-detection method, respectively. The TT results of the three methods were compared. Results: The proportion of 233 failed TT tests from the total number of samples was 1.1% (233/21 359). There were 41.2% (96/233) samples with lipids, 23.2% (54/233) samples with heparin interference, 22.3% (52/233) samples with oral anticoagulant, and 13.3% (31/233) samples with micro-coagulation or insufficient plasma volume among these test failure samples. The classifications for these alarm information of coagulation curves showed on the instrument were as follows: 32.6% (76/233) of samples with higher changes in absorbance at baseline (SD>2 mAbs), 30.5% (71/233) of samples without peak values of second derivative, 25.8% (60/233) of samples with absorbance difference<35 mAbs between baseline and plateau period, 8.6% (20/233) samples with too low starting point or no starting point, and 2.6% (6/233) samples without coagulation curves. Among these 233 samples, there were 55.8% (130/233) samples that could be manually judged according to the reaction principle and standard coagulation curve pattern. Among the 96 samples that failed in coagulation method due to lipemia, there were 78 samples with sufficient blood volume tested by magnetic bead method. The TT results of the high-speed centrifugal redetection method, artificial coagulation curve interpretation method and magnetic bead method were 14.10 (14.80, 13.38) s, 14.30 (14.99, 13.60) s, and 15.65 (17.25, 14.65) s, respectively, but the difference was not statistically significant (P=0.055). For 78 lipid samples, there was a correlation between the results of the artificial coagulation curve interpretation method and the results of magnetic bead method (r=0.99,P=0.001). Conclusions: For those samples failed in TT detection by coagulation method on automatic coagulation instrument, the cause of failure can be analyzed through coagulation curve and alarm information. For the lipid samples, TT results can be obtained by manual interpretation method, high-speed centrifugation method and magnetic bead method.

The effects of fructose diphosphate on routine coagulation tests in vitro

To evaluate the effects of fructose diphosphate (FDP) on routine coagulation tests in vitro, we added FDP into the mixed normal plasma to obtain the final concentration of 0, 1, 2, 3, 4, 5, 6, 10, 15, 20, 25, 30 and 35 mg/mL of drug. Prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen (FBG) and thrombin time (TT) of samples were analyzed with blood coagulation analyzers from four different manufacturers(Sysmex, Stago, SEKISUI and Werfen) and their corresponding reagents, respectively. Before the experiment, we also observed whether there were significant differences in coagulation test results of different lots of reagents produced by each manufacturer. At the same time as the four routine clotting tests, the Sysmex blood coagulation analyzer and its proprietary analysis software were used to detect the change of maximum platelet aggregation rate in platelet-rich plasma after adding FDP (0, 1, 2, 3, 4, 5 and 6 mg/mL). The results of PT, aPTT and TT showed a FDP (0-35 mg/mL) concentration-dependent increase and a FBG concentration-dependent decrease. The degree of change (increase or decrease) varied depending on the assay system, with PT and aPTT being more affected by the Sysmex blood coagulation testing instrument reagent system and less affected by CEKISUI, TT less affected by CEKISUI and more affected by Stago, and FBG less affected by Stago and more affected by Sysmex. The results of PT, aPTT and TT were statistically positively correlated with their FDP concentrations, while FBG was negatively correlated. The correlation coefficients between FDP and the coagulation testing systems of Sysmex, Stago, Werfen and SEKISUI were 0.975, 0.988, 0.967, 0.986 for PT, and 0.993, 0.989, 0.990 and 0.962 for aPTT, 0.994, 0.960, 0.977 and 0.982 for TT, - 0.990, - 0.983, - 0.989 and - 0.954 for FBG, respectively. Different concentrations of FDP (0, 1, 2, 3, 4, 5 and 6 mg/mL) had different effects on the maximum aggregation rate of platelet induced by the agonists of adenosine diphosphate (ADP, 5 µmol/L), arachidonic acid (Ara, 1 mmol/L), collagen (Col, 2.5 µg/mL) and epinephrine (Epi,10 µmol/L), but the overall downward trend was consistent, that is, with the increase of FDP concentration, the platelet aggregation rate decreased significantly. Our experimental study demonstrated a possible effect of FDP on the assays of coagulation and Platelet aggregation, which may arise because the drug interferes with the coagulation and platelet aggregation detection system, or it may affect our in vivo coagulation system and Platelet aggregation function, the real mechanism of which remains to be further verified and studied.

Chemical Structure and Anticoagulant Property of a Novel Sulfated Polysaccharide from the Green Alga Cladophora oligoclada

Marine macroalgae are efficient producers of sulfated polysaccharides. The algal sulfated polysaccharides possess diverse bioactivities and peculiar chemical structures, and represent a great potential source to be explored. In the present study, a heparinoid-active sulfated polysaccharide was isolated from the green alga Cladophora oligoclada. Results of chemical and spectroscopic analyses indicated that the sulfated polysaccharide was composed of →6)-β-d-Galp-(1→, β-d-Galp-(1→, →6)-α-d-Glcp-(1→ and →3)-β-d-Galp-(1→ units with sulfate esters at C-2/C-4 of →6)-β-d-Galp-(1→, C-6 of →3)-β-d-Galp-(1→ and C-3 of →6)-α-d-Glcp-(1→ units. The branches consisting of β-d-Galp-(1→ and →6)-β-d-Galp-(1→ units were located in C-3 of →6)-β-d-Galp-(1→ units. The sulfated polysaccharide exhibited potent anticoagulant activity in vitro and in vivo as evaluated by activated partial thromboplastin time (APTT), thrombin time, and the fibrinogen level. For the APTT, the signal for clotting time was more than 200 s at 100 μg/mL in vitro and at 15 mg/kg in vivo. The obvious thrombolytic activity of the sulfated polysaccharide in vitro was also found. The mechanism analysis of anticoagulant action demonstrated that the sulfated polysaccharide significantly inhibited the activities of all intrinsic coagulation factors, which were less than 1.0% at 50 μg/mL, but selectively inhibited common coagulation factors. Furthermore, the sulfated polysaccharide strongly stimulated the inhibition of thrombin by potentiating antithrombin-III (AT-III) or heparin cofactor-II, and it also largely promoted the inhibition of factor Xa mediated by AT-III. These results revealed that the sulfated polysaccharide from C. oligoclada had potential to become an anticoagulant agent for prevention and therapy of thrombotic diseases.

Coronavirus-induced coagulopathy during the course of disease

BACKGROUND

A significant proportion of patients with coronavirus disease 19 (COVID-19) suffer from excessive coagulation activation and coagulopathy which is associated with an increased risk of venous and arterial thromboembolism and adverse outcome. Our study investigates coagulation markers and the incidence of thromboembolic events in COVID-19 patients receiving recommended anticoagulation strategies.

METHODS

In a retrospective single-center analysis at the University Hospital Zurich, Switzerland, we investigated 31 adult COVID-19 patients between April 6th and May 13th, 2020 and with at least one laboratory assessment of the coagulation markers prothrombin time/Quick, thrombin time, fibrinogen and D-dimers. For antithrombotic prophylaxis low-molecular-weight-heparin or unfractionated heparin was administered and two patients with heparin-induced thrombocytopenia received argatroban.

RESULTS

We analyzed 31 patients (68% male, mean age 60± SD 15 years). 22 (71%) of these required intensive care unit treatment, 5 (16%) were hospitalized in a ward, and 4 (13%) were outpatients. Mean fibrinogen levels were markedly elevated to 6.4± SD 1.8g/l, with a peak in the third week of the disease and no significant decrease over time. D-dimers were elevated to a mean value of 5.1±4.4mg/l with peak levels of 6.8±5.3mg/l in the fourth week of disease, and a subsequent decrease. Platelet count (308±136G/l) and PT/Quick (85±22%) showed no significant changes over time. Sensitivity analyses for patients treated in the ICU showed that D-dimer levels were higher in this group. The results of other sensitivity analyses were comparable. Thromboembolic events were diagnosed in 4 (13%) patients and 5 (16%) patients died during the observation period.

CONCLUSION

We find coagulation alterations in COVID-19 patients indicating significant hypercoagulability. These alterations are visible despite antithrombotic treatment, and peak around week 3-4 of the disease.

Discovery of Benzyl Tetraphosphonate Derivative as Inhibitor of Human Factor Xia

The inhibition of factor XIa (FXIa) is a trending paradigm for the development of new generations of anticoagulants without a substantial risk of bleeding. In this report, we present the discovery of a benzyl tetra-phosphonate derivative as a potent and selective inhibitor of human FXIa. Biochemical screening of four phosphonate/phosphate derivatives has led to the identification of the molecule that inhibited human FXIa with an IC50 value of ∼7.4 μM and a submaximal efficacy of ∼68 %. The inhibitor was at least 14-fold more selective to FXIa over thrombin, factor IXa, factor Xa, and factor XIIIa. It also inhibited FXIa-mediated activation of factor IX and prolonged the activated partial thromboplastin time of human plasma. In Michaelis-Menten kinetics experiment, inhibitor 1 reduced the VMAX of FXIa hydrolysis of a chromogenic substrate without significantly affecting its KM suggesting an allosteric mechanism of inhibition. The inhibitor also disrupted the formation of FXIa - antithrombin complex and inhibited thrombin-mediated and factor XIIa-mediated formation of FXIa from its zymogen factor XI. Inhibitor 1 has been proposed to bind to or near the heparin/polyphosphate-binding site in the catalytic domain of FXIa. Overall, inhibitor 1 is the first benzyl tetraphosphonate small molecule that allosterically inhibits human FXIa, blocks its physiological function, and prevents its zymogen activation by other clotting factors under in vitro conditions. Thus, we put forward benzyl tetra-phosphonate 1 as a novel lead inhibitor of human FXIa to guide future efforts in the development of allosteric anticoagulants.

A low-cost laboratory-based method for predicting newly diagnosed biopsy-proven diabetic nephropathy in people with type 2 diabetes

AIMS

To identify significant prognostic factors for newly diagnosed biopsy-proven diabetic nephropathy using routine laboratory measures, from which to derive a low-cost explanatory model, and to use this model to examine associations between the potential low-cost test panels and the risk of diabetic nephropathy in people with type 2 diabetes with normal kidney function.

METHOD

A population-based case-control study was undertaken to test the association between diabetic nephropathy and 47 laboratory variables using a 'hypothesis-free' strategy and five routinely recorded factors in diabetes care (BMI, systolic and diastolic blood pressure, HbA_1c , fasting glucose). Factors that were significant after Bonferroni correction were included in different test panels and used to develop diabetic nephropathy (outcome) explanatory models. Models were derived using risk-set sampling among 950 biopsy-proven diabetic nephropathy cases newly diagnosed in the period between 2012 and 2018 and among 4750 age- and gender-matched controls.

RESULTS

A total of 15 Bonferroni-corrected significant laboratory predictors in the three test panels (blood cell, serum electrolytes and blood coagulation) were identified through multivariable analysis and used to develop the three explanatory models. The optimism-adjusted C-statistics and calibration slope were 0.725 (95% CI 0.723-0.728) and 0.978 (95% CI 0.912-0.999) for the blood cell model, 0.688 (95% CI 0.686-0.690) and 0.923 (95% CI 0.706-0.977) for the serum electrolytes model, 0.648 (95% CI 0.639-0.658) and 0.914 (95% CI 0.641-1.115) for the blood coagulation model, respectively.

CONCLUSIONS

A total of 15 predictors were significantly associated with newly diagnosed biopsy-proven diabetic nephropathy in type 2 diabetes. The blood cell model appeared to be the low-cost model with the best predictive ability.

Sulfation, structural analysis, and anticoagulant bioactivity of ginger polysaccharides

In this study, ginger polysaccharide (GP), ginger polysaccharide 1 (GP1), and ginger polysaccharide 2 (GP2) from ginger were firstly modified by sulfation. Fourier transform infrared, and nuclear magnetic resonance spectra investigation of sulfated ginger polysaccharide (SGP), sulfated ginger polysaccharide 1 (SGP1), and sulfated ginger polysaccharide 2 (SGP2) revealed that the sulfation successfully occurred with the characteristic absorption peak of polysaccharide. Congo red experiment showed that triple helical structure existed in SGP and SGP1, but random coils existed in SGP2. SGP, SGP1, and SGP2 all showed a rough and rugged surface with plenty of small pores. The blood clotting time of SGP2 or SGP at 2 mg/mL in activated partial thromboplastin time (APTT) assay was 41.42 or 38.01 s, respectively, which were approximately 1.33- and 1.22-fold longer than that of the physiological saline. Compared to the saline control group, prothrombin time (PT) was increased by 1.22-fold with the addition of GP at 2 mg/mL. However, no clotting inhibition phenomenon was observed in thrombin time test even at the concentrations that APTT and PT were obviously prolonged. It indicated that GP2, SGP2, and SGP inhibited the intrinsic pathway of coagulation, but GP inhibited both the intrinsic and extrinsic pathways of coagulation. Hence, ginger polysaccharides might be used as anticoagulants and therapeutic reagents for thrombosis.

Novel Anticoagulant Peptide from Lactoferrin Binding Thrombin at the Active Site and Exosite-I

Thrombin is currently one of the important targets for the treatment and prevention of thrombosis. At present, there are few reports on the application of lactoferrin peptides in anticoagulation. In this study, a peptide with the amino acid sequence of LRPVAAEIY (LF-LR) derived from lactoferrin was shown to possess antithrombotic activity. LF-LR (5 mM) significantly prolonged activated partial thromboplastin time, prothrombin time, and thrombin time for 13.4, 1.7, and 5.1 s, respectively. It prolonged the coagulation time of fibrinogen from 15.3 ± 0.4 to 20.2 ± 0.5 s by affecting the conformation of thrombin. Using circular dichroism analysis, LF-LR can increase the α-helix content of thrombin from 25.6 to 56.7% and made the β-sheet disappear. In addition, LF-LR also quenched fluorescence of thrombin at about 346 nm (λ_Ex = 280 nm). By means of molecular docking, it was found that LF-LR could bind to both the active site and the exosite-I of thrombin, and the combined LYS60F, TRP60D, ASP189, LYS36, and ARG77A are typical amino acids in the two domains, respectively.

Isolation and Characterization of a Heparin-Like Compound with Potent Anticoagulant and Fibrinolytic Activity from the Clam Coelomactra antiquata

Heparin from mollusks with unique sulfated glycosaminoglycan exhibits strong anti-thrombotic activities. This study reports on a purified heparinoid from Coelomactra antiquata, which shows potent anticoagulant and fibrinolytic abilities. Its structure was characterized by infrared spectroscopy, high-performance liquid chromatography, and one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy. Its fibrinolytic activity was determined in vitro and in vivo. Its anticoagulant activity was determined by activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). The results indicated that clam heparinoid was a homogeneous glycosaminoglycan with a molecular weight of 30.99 kDa, mainly composed of →4)-α-IdoA2S-(1→4)-α-GlcNS3S6S (or GlcNS6S)-(1→4)-β-GlcA-(1→4)-α-GlcNS6S (or GlcNAC)-(1→. Furthermore, this heparinoid showed a highly anticoagulant titer and fibrinolytic value of 149.63 IU/mg and 1.96 IU/mg, respectively. In summary, clam heparinoid shows great potential for application in the clinic and antithrombotic drugs industry.

Randomized phase 2 trial comparing JNJ-9375, a thrombin-directed antibody, with apixaban for prevention of venous thrombosis

BACKGROUND

JNJ-9375 is an antibody against exosite 1 on thrombin, inhibits substrate binding but not catalytic activity.

OBJECTIVE

To examine the possibility that JNJ-9375 attenuates thrombosis without affecting hemostasis, we compared the efficacy and safety of JNJ-9375 and apixaban.

METHODS

In this double-blind, double-dummy phase 2 trial, 308 patients undergoing knee arthroplasty were randomized to receive either a single postoperative intravenous infusion of JNJ-9375 in doses ranging from 0.3 to 1.8 mg/kg or apixaban (2.5 mg twice daily). The primary efficacy endpoint was the incidence of venous thromboembolism (assessed by mandatory unilateral venography or confirmed symptomatic events). The primary safety outcome was the composite of major, clinically relevant nonmajor, and minimal bleeding. Thrombin times were measured to assess JNJ-9375 activity.

RESULTS

A total of 239 of the 308 patients (77.6%) were included in the modified intention-to-treat analysis. Of these, 238 had evaluable venograms and one had symptomatic deep-vein thrombosis confirmed by ultrasound. Despite dose-dependent thrombin time prolongation, the primary efficacy outcome occurred in 59 of 190 patients (31.1%) in the combined JNJ-9375 groups as compared with 6 of 49 patients (12.2%) given apixaban (odds ratio 3.2; two-sided 80% confidence interval 1.8-5.8; P = .011). The excess events with JNJ-9375 compared with apixaban were consistent across all JNJ-9375 dosing cohorts and there was no evidence of improved efficacy with higher JNJ-9375 doses. There were no major bleeds with JNJ-9375 or apixaban, and rates of any bleeding were similar with the highest and lowest JNJ-9375 doses.

CONCLUSIONS

JNJ-9375 was safe but less effective than apixaban. This may reflect weak thrombin inhibition or inability of JNJ-9375 to attenuate the growth of thrombi that formed before drug administration.

Assessment of anti-coagulant activity of Nelumbo nucifera fruit

The herbal agents rich in flavonoids are progressively becoming popular these days as they are considered to have anti-oxidant effects and also lack bothersome effects. That's why existing research was encircled around the anti-coagulant effect of Nelumbo nucifera fruit (NNF) as it is also a rich source of flavonoids and cultivated in abundance especially in tropical regions of Asia but its usefulness as anti-coagulant agent was never determined pharmacologically. Anticoagulant assessment was done in thirty five male Wister rats which were separated equally in 5 groups. Results of the current study revealed that NNF 200mg/kg significantly prolonged prothrombin time and thrombin time, whereas fibrinogen level was highly significantly reduced as compared to control. Fibrinogen level was also reduced highly significantly with NNF 100 mg/kg as compared to control without affecting other parameters of coagulation i.e. activated partial thromboplastin time, prothrombin time and thrombin time. NNF exhibited strong anti-coagulant activity which may be due to the inhibitory effects on platelet activation, adhesion and aggregation along with inhibitory effects on thromboxane A2 formation. Presence of alkaloid i.e. neferine and flavonoids in it may be a reason of its anti-coagulant activity but more pre-clinical and clinical evaluation needs to be conducted to establish these findings.

The In Vitro Effects of Pentamidine Isethionate on Coagulation and Fibrinolysis

Pentamidine is bis-oxybenzamidine-based antiprotozoal drug. The parenteral use of pentamidine appears to affect the processes of blood coagulation and/or fibrinolysis resulting in rare but potentially life-threatening blood clot formation. Pentamidine was also found to cause disseminated intravascular coagulation syndrome. To investigate the potential underlying molecular mechanism(s) of pentamidine's effects on coagulation and fibrinolysis, we studied its effects on clotting times in normal and deficient human plasmas. Using normal plasma, pentamidine isethionate doubled the activated partial thromboplastin time at 27.5 µM, doubled the prothrombin time at 45.7 µM, and weakly doubled the thrombin time at 158.17 µM. Using plasmas deficient of factors VIIa, IXa, XIa, or XIIa, the concentrations to double the activated partial thromboplastin time were similar to that obtained using normal plasma. Pentamidine also inhibited plasmin-mediated clot lysis with half-maximal inhibitory concentration (IC50) value of ~3.6 μM. Chromogenic substrate hydrolysis assays indicated that pentamidine inhibits factor Xa and plasmin with IC50 values of 10.4 µM and 8.4 µM, respectively. Interestingly, it did not significantly inhibit thrombin, factor XIa, factor XIIIa, neutrophil elastase, or chymotrypsin at the highest concentrations tested. Michaelis-Menten kinetics and molecular modeling studies revealed that pentamidine inhibits factor Xa and plasmin in a competitive fashion. Overall, this study provides quantitative mechanistic insights into the in vitro effects of pentamidine isethionate on coagulation and fibrinolysis via the disruption of the proteolytic activity of factor Xa and plasmin.

Antithrombotic Activity of Brewers' Spent Grain Peptides and their Effects on Blood Coagulation Pathways

Antithrombotic activity of brewers' spent grain peptides before and after simulated gastrointestinal digestion and their effects on blood coagulation pathways were evaluated. Two hydrolysates were produced using sequential enzymatic systems: alkaline protease + Flavourzyme (AF) and neutral protease + Flavourzyme (PF). Simulation of gastrointestinal digestion of AF and PF hydrolysates was made using porcine pepsin and pancreatin enzymes, obtaining the corresponding digested samples: AFD and PFD, respectively. Peptides were fractionated by ultrafiltration using a 1 kDa cut-off membrane. Hydrolysates had peptides with medium and low molecular weights (2100 and 500 Da, respectively), and Glu, Asp, Leu, Ala, and Phe were the most abundant amino acids. Gastrointestinal digested hydrolysates presented high proportion of small peptides (~500 Da), and higher amount of Val, Tyr, and Phe than hydrolysates. Mass spectrum (HDMS Q-TOF) of AFD-ultrafiltered fraction <1 kDa exhibited peptides from 500 to 1000 Da, which are not present in AF. PFD showed the generation of new peptides from 430 to 1070 Da. All samples showed thrombin inhibitory activity. However, no effect was observed on prothrombin time. Peptides <1 kDa from hydrolysates and digested samples delayed thrombin and thromboplastin time respect to the control (~63%). Also the samples showed thrombin inhibitory activity at common pathway level. Thus, brewers' spent grain peptides exerted their antithrombotic activity by inhibiting the intrinsic and common pathways of blood coagulation. This is the first report to demonstrate that brewers' spent grain peptides are able to delay clotting time after simulated gastrointestinal digestion.

Effects of Freeze-Thaw Times on Screening Coagulation Tests and Factors VIII and IX Activities in Citrate-Anticoagulated Plasma at -20°C and -80°C

BACKGROUND

Accurate determination of screening coagulation tests and factors VIII and IX activities (FVIII:C and FIX:C) in fresh plasma is very important for diagnosing abnormalities in the intrinsic or extrinsic coagulation pathways and factor deficiencies. If thawed samples cannot be detected for all required items at the same time, or need to be re-tested or re-stored, the thawed samples need to be re-frozen. We planned to perform in-house validation studies on freeze-thawed samples for screening coagulation tests, FVIII:C and FIX:C.

METHODS

Mean percent changes, numbers of samples with > 10% changes, and difference plots were evaluated to determine clinically relevant differences between results for fresh and freeze-thawed samples. The statistical significance of differences between repeated-measure multiple groups and baseline values were evaluated by repeated-measures analysis of variance.

RESULTS

The acceptable freeze-thaw cycles for activated partial thromboplastin time, fibrinogen, prothrombin time/international normalized ratio, thrombin time, and FIX:C were three times at -20°C/-80°C, while the acceptable freeze-thaw cycles for FVIII:C were three times at -80°C and once at -20°C.

CONCLUSIONS

The freeze-thaw results on stabilities were affected by time and temperature, with lower temperature and fewer times associated with more stable activity.

Clinical significance of fibrotic, haemostatic and endotoxic changes in patients with liver cirrhosis

BACKGROUND AND STUDY AIMS

To investigate the relationship among fibrotic, haemostatic and endotoxic changes in patients with different degrees of liver cirrhosis.

PATIENTS AND METHODS

Liver fibrotic markers, including hyaluronic acid (HA), Ccollagen IV (Col-IV), laminin (LN), and N-terminal pro-peptide of collagen type III (PIIINP), were determined by radioimmunoassay. A series of haemostatic tests, including prothrombin time (PT), international normalized ratio, activated partial thromboplastin time, antithrombin-III, thrombin time, fibrinogen, fibrin(ogen) degradation product and D-dimer were determined using an automatic coagulation analyszer. Plasma levels of endotoxin were detected quantitatively using an endotoxin detection kit. Correlation analysis of the data was performed.

RESULTS

Based on Child-Pugh classification, statistically significant differences in fibrotic markers and haemostatic parameters were found in 249 patients with liver cirrhosis, while no significant differences in endotoxin levels were observed. Based on ascites classification, statistically significant differences in fibrotic markers (such as HA, Col-IV and PIIINP, except for LN) and haemostatic parameters were found. As for endotoxin levels, there were significant differences between the ascites, spontaneous bacterial peritonitis (SBP) and no-ascites groups, while no significant differences were observed between the ascites and SBP groups. Correlation analysis demonstrated some correlation among fibrotic markers, haemostatic parameters and endotoxin.

CONCLUSIONS

A close relationship exists between the severity of cirrhosis and fibrotic changes, as well as haemostatic changes. Endotoxin may be an important contributing factor to the development of ascites in cirrhosis. Some correlation may exist between fibrosis, haemostatic and endotoxin.

How and when to measure anticoagulant effects of direct oral anticoagulants? Practical issues

Direct oral anticoagulants (DOACs) do not require dose adjustment based on laboratory testing. However, it might be necessary to measure their plasma concentrations in the following specific situations: 1) before thrombolytic therapy in patients with stroke; 2) before surgery or invasive procedure; 3) in case of adverse events (thrombosis or hemorrhage); 4) when immediate reversal of anticoagulation is needed; 5) in patients with extreme body weight; 6) when administering additional drugs potentially interfering with DOACs; and 7) when overdosage is suspected regardless of concomitant bleeding. Basic coagulation tests, such as prothrombin and activated partial thromboplastin time, should not be used as standalone tests to assess the levels of anticoagulation as they are not specific for DOACs and their results are dependent on the type of reagent used for testing. Plasma DOAC concentrations should be assessed by dedicated tests: dilute thrombin time or ecarin tests (for dabigatran) or anti-factor Xa assays (for anti-factor Xa inhibitors). Dedicated tests should be calibrated against their respective plasma calibrators at certified DOAC concentrations and results should be expressed as ng/ml. Caution should be exerted when interpreting the results of the most common hemostatic parameters such as antithrombin, proteins C and S, lupus anticoagulant, or individual coagulation factors, as they may be strongly affected by the presence of a DOAC. Whenever possible, these parameters should be measured 4 to 5 days after discontinuation of DOAC anticoagulation.

Thrombin generation and platelet activation in cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy - A prospective cohort study

Background and objectives

Cytoreductive surgery (CRS) with hyperthermic intraperitoneal peroperative chemotherapy (HIPEC), indicated for patients with peritoneal metastases from digestive or gynecological malignancies alike, demonstrates a considerable impact on hemostatic metabolism, both on platelet and on coagulation level. The potential hemostatic interference in CRS and HIPEC is phase dependent. The hypothesis of this prospective cohort study is that the procedure exposed an increased thrombotic risk, resulting in a faster and increased thrombin generation and hyper platelet function.

Methods

This study explores the combined use of ROTEM (rotational thromboelastometry), PACT (platelet activation test) and CAT (thrombin generation test) assays during CRS and HIPEC with a follow-up of 7 days postoperative in 27 patients with confirmed histological diagnosis of peritoneal disease.

Results

Platelet reactivity (relative to before incision values) to CRP (collagen-related peptide) (p value 0.02) and TRAP (thrombin receptor activator peptide) (p value 0.048) seems to be slightly reduced during CRS and HIPEC with regard to αIIbβ3 activation, while P-selectin expression is not affected. During surgery, CAT demonstrates that, the LT (lagtime) (p value 0.0003) and TTP (time-to-thrombin peak) values (p value 0.002) decrease while and the TP (thrombin peak) (p value 0.004) and ETP (endogenous thrombin potential) (p value 0.02) increase. Subsequently, after surgery, the LT and TTP increase and ETP and TP decrease in time. ROTEM EXTEM (extrinsic) MCF (maximum clot firmness) (p value 0.005), INTEM (intrinsic) MCF (p value 0.003) and FIBTEM (fibrinogen) MCF (p value <0.001) decreased during CRS. At day 7 INTEM and FIBTEM MCF values (p values of 0.004 and <0.001) were significantly higher than before surgery. No considerable changes in platelet count and hemoglobin concentration and absence of leukopenia are noticed.

Conclusion

This approach detects changes in coagulation much earlier than noticed by standard coagulation tests.

Anticoagulant Activities of Indobufen, an Antiplatelet Drug

Indobufen is a new generation of anti-platelet aggregation drug, but studies were not sufficient on its anticoagulant effects. In the present study, the anticoagulant activity of indobufen was determined by monitoring the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) in rabbit plasma. We evaluated the anticoagulant mechanisms on the content of the platelet factor 3,4 (PF3,4), and the coagulation factor 1, 2, 5, 8, 10 (FI, II, V, VIII, X) in rabbits, as well as the in vivo bleeding time and clotting time in mice. The pharmacodynamic differences between indobufen and warfarin sodium, rivaroxaban, and dabigatran were further studied on thrombus formation and the content of FII and FX in rats. Animal experiments showed that intragastric-administrated indobufen can significantly reduce the APTT, PT, TT, PF3, FI, II, V, VIII, and X plasma contents. Its inhibitory effect on plasma FII was better than thrombin inhibitor dabigatran with effect on FX better than FXa inhibitor rivaroxaban. These results suggest that indobufen has some anticoagulant effects as strong as some conventional anticoagulants. The mechanism may be related to both exogenous and endogenous coagulation system.

Novel isoguanine derivative of unlocked nucleic acid-Investigations of thermodynamics and biological potential of modified thrombin binding aptamer

Thrombin binding aptamer (TBA), is a short DNA 15-mer that forms G-quadruplex structure and possesses anticoagulant properties. Some chemical modifications, including unlocked nucleic acids (UNA), 2'-deoxy-isoguanosine and 2'-deoxy-4-thiouridine were previously found to enhance the biological activity of TBA. In this paper, we present thermodynamic and biological characteristics of TBA variants that have been modified with novel isoguanine derivative of UNA as well as isoguanosine. Additionally, UNA-4-thiouracil and 4-thiouridine were also introduced simultaneously with isoguanine derivatives. Thermodynamic analysis indicates that the presence of isoguanosine in UNA or RNA series significantly decreases the stability of G-quadruplex structure. The highest destabilization is observed for substitution at one of the G-tetrad position. Addition of 4-thiouridine in UNA or RNA series usually decreases the unfavorable energetic cost of the presence of UNA or RNA isoguanine. Circular dichroism and thermal denaturation spectra in connection with thrombin time assay indicate that the introduction of UNA-isoguanine or isoguanosine into TBA negatively affects G-quadruplex folding and TBA anticoagulant properties. These findings demonstrate that the highly-ordered structure of TBA is essential for inhibition of thrombin activity.

Interlaboratory variability in the measurement of direct oral anticoagulants: results from the external quality assessment scheme

Essentials Tests for direct oral anticoagulants (DOACs) are not widely applied. These tests are perceived to be difficult to run and subjected to large between-lab variation. We carried out proficiency testing surveys for DOAC testing in Italy. Interlab variability was small and similar to that of the international normalised ratio.

SUMMARY

Background Tests for direct oral anticoagulants (DOACs) are not widely available. The perception that they are difficult to perform and are subject to large between-laboratory variation makes their implementation difficult. Aims We carried out proficiency-testing surveys for DOACs within the activity of the external quality-assessment scheme of the Italian Federation of Thrombosis Centers. Design Participants were provided with coded freeze-dried plasmas without or with graded concentrations of the three main DOACs, and asked to measure prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time and DOAC concentrations with dedicated tests. The results were centralized for statistical analysis. Results and conclusions All participants (n = 235) reported results for PT and APTT, and approximately one-third reported results for DOAC concentration. PT and APTT showed variable responsiveness to DOACs: PT was more responsive to rivaroxaban than to dabigatran or apixaban. APTT was more responsive to dabigatran than to rivaroxaban or apixaban. The thrombin time ratio (test/normal) was close to unity for plasmas without dabigatran, and was high (i.e. 7.6-fold or 15.4-fold longer than the plasma free from the drug) for plasmas containing dabigatran at low (i.e. 42 ng mL-1 ) or high (i.e. 182 ng mL-1 ) concentration. Dedicated tests were responsive to the respective drugs, and their interlaboratory variability was relatively small (overall coefficients of variation of 8.7%, 8.4% or 10.3% for dabigatran, rivaroxaban and apixaban, respectively) and was comparable to that observed within the same survey for the International Normalized Ratio (i.e. 11.4%). In conclusion, tests for DOAC measurement performed reasonably well in a national quality-control scheme. Regulatory authorities should urgently issue recommendations on their use, and clinical laboratories should make them available.

Metabolomic profiling of the effects of Curcumae rhizoma and Sparganii rhizome on stress-led blood stasis

Blood stasis (BS) is a complex syndrome with blood flow retardation or cessation. The Traditional Chinese Medicine, Curcumae rhizome (CR) and Sparganii rhizome (SR), showed promising effects on this disease, and especially effective when used in combination. However, the detailed influence of the TCMs on the BSS disturbed metabolic pathways was still unclear. In this study, a BS model was constructed in SD rat and the TCMs were used individually or in combination to assess the effects. As a result, combination of CR and SR led to the improvement in hemorheology parameters of up to 80% in the BS model. Further analyzing using metabolomics showed several metabolic pathways, including center carbon metabolism, amino acid metabolism, etc., recovered to the normal levels after treatment. Informatively, tyrosine and thymidine exhibited potential importance in the BSS and its treatment process. From these results, the metabolic profiles of BS and the SR-CR treatment were provided, which may helpful for better understanding the BSS mechanism and the development of more effective therapies.

Differences in the clinically effective molar concentrations of four direct thrombin inhibitors explain their variable prothrombin time prolongation

Four direct thrombin inhibitors (DTIs), lepirudin, bivalirudin, argatroban, and melagatran, differ in their ability to prolong the prothrombin time (PT). Paradoxically, the DTI in clinical use with the lowest affinity for thrombin (argatroban) causes the greatest PT prolongation. We compared the effects of these DTIs on various clotting assays and on inhibition of human and bovine factor Xa (FXa). On a mole-for-mole basis, lepirudin was most able to prolong the PT, activated partial thromboplastin time (APTT), and thrombin clotting time (TCT), whereas argatroban had the least effect. At concentrations that doubled the APTT (argatroban, 1 μmol/l; melagatran, 0.5 μmol/l; bivalirudin, 0.25 μmol/l; lepirudin, 0.06 μmol/l), the rank order for PT prolongation was: argatroban > melagatran > bivalirudin > lepirudin. Although the Ki’s associated with inhibition of human FXa by melagatran (1.4 μmol/l) and argatroban (3.2 μmol/l) approach their therapeutic concentrations, inhibition of FXa did not appear to be a major contributor to PT prolongation, since argatroban also prolonged the PT of bovine plasma (despite a Ki for bovine FXa of 2,600 μmol/l). Only melagatran inhibited prothrombinase-bound FXa. We conclude that the differing effects of the DTIs on PT prolongation are primarily driven by their respective molar plasma concentrations required for clinical effect. DTIs with a relatively low affinity for thrombin require high plasma concentrations to double the APTT; these higher plasma concentrations, in turn, quench more of the thrombin generated in the PT, thereby more greatly prolonging the PT.

A novel fibrinogen Bβ chain frameshift mutation in a patient with severe congenital hypofibrinogenaemia

Congenital afibrinogenemia and severe hypofibrinogenemia are severe bleeding disorders characterized by either undetectable or very low levels of fibrinogen in patients’ plasma and platelets. A majority of the reported cases are caused by mutations in the fibrinogen Aα chain. In this study, we identified a genetic defect in the fibrinogen Bβ-chain (FGB) underlying severe hypofibrinogenemia. The propositus frequently displayed bleeding episodes with a prolonged blood-clotting time (thrombin time > 180 s,activated partial thromboplastin time > 300 s, prothrombin time > 120 s) and had a very low level of plasma fibrinogen (1.7–1.8 mg/dl). His parents had a consanguineous marriage, and their functional and immunological fibrinogen was approximately half of the normal level.The platelet fibrinogen level of the propositus could not be detected by western blotting, and his platelet aggregation was severely impaired. DNA screening of the whole fibrinogen gene revealed a homozygous GGGG→GGG mutation at nucleotide 7969–7972 in his FGB gene. The propositus’ parents are both heterozygous for this mutation. This mutation contributes to Gly419→Val, and the 419–434 codons are frame shifted, and a stop codon is formed at codon 435.The predicted truncated Bβ-chain is 27 amino acids shorter than the normal Bβ-chain and a central β-strand in the globular βC domain is absent,which may lead to destabilization of the entire β-domain. To the best of our knowledge, this is the first report of such a mutation which is associated with severe hypofibrinogenemia.

A new recombinant thrombolytic and antithrombotic agent with higher fibrin affinity – a staphylokinase variant

The recombinant protein SAK-RGD-K2-Hir is characterized by its fibrin-specific properties of plasminogen activation combined with antithrombin and antiplatelet activities. It was previously shown in our in-vitro studies to be a more potent and faster-acting thrombolytic agent compared with standard r-SAK. In order to document the effects of the thrombolytic potential of SAKRGD- K2-Hir we examined this protein in an electrically induced carotid artery thrombosis model and stasis-induced venous model in rats. In the arterial thrombosis model, a bolus injection of SAK-RGD-K2-Hir was less effective than rt-PA and r-SAK. However, the most effective in the improvement and maintenance of carotid patency and in arterial thrombus mass reduction was SAK-RGD-K2. In contrast, all r-SAK derivatives reduced venous thrombus weight significantly in comparison to r-SAK and r-Hir. However, the most observable decrease in thrombus weight was obtained after application of recombinant proteins containing the r-Hir.The bleeding time was significantly prolonged in the animals treated with proteins containing r-Hir at a dose of 1.0 mg/kg.There were no observable changes in plasma fibrinogen concentration.In conclusion,our findings show thrombolytic activity in intravenous bolus injection of the novel thrombolytic agent SAK-RGD-K2-Hir in rats.Although this protein compares favourably with r-SAK in rat venous thrombolysis, we were unable to confirm the beneficial effects of SAK-RGDK2- Hir over r-SAK and rt-PA in the carotid artery thrombolysis model. Furthermore, our results also suggest that SAKRGD- K2-Hir bears a risk of bleeding, but this may be true for higher doses.

Idarucizumab for Dabigatran Reversal - Full Cohort Analysis

BACKGROUND

Idarucizumab, a monoclonal antibody fragment, was developed to reverse the anticoagulant effect of dabigatran.

METHODS

We performed a multicenter, prospective, open-label study to determine whether 5 g of intravenous idarucizumab would be able to reverse the anticoagulant effect of dabigatran in patients who had uncontrolled bleeding (group A) or were about to undergo an urgent procedure (group B). The primary end point was the maximum percentage reversal of the anticoagulant effect of dabigatran within 4 hours after the administration of idarucizumab, on the basis of the diluted thrombin time or ecarin clotting time. Secondary end points included the restoration of hemostasis and safety measures.

RESULTS

A total of 503 patients were enrolled: 301 in group A, and 202 in group B. The median maximum percentage reversal of dabigatran was 100% (95% confidence interval, 100 to 100), on the basis of either the diluted thrombin time or the ecarin clotting time. In group A, 137 patients (45.5%) presented with gastrointestinal bleeding and 98 (32.6%) presented with intracranial hemorrhage; among the patients who could be assessed, the median time to the cessation of bleeding was 2.5 hours. In group B, the median time to the initiation of the intended procedure was 1.6 hours; periprocedural hemostasis was assessed as normal in 93.4% of the patients, mildly abnormal in 5.1%, and moderately abnormal in 1.5%. At 90 days, thrombotic events had occurred in 6.3% of the patients in group A and in 7.4% in group B, and the mortality rate was 18.8% and 18.9%, respectively. There were no serious adverse safety signals.

CONCLUSIONS

In emergency situations, idarucizumab rapidly, durably, and safely reversed the anticoagulant effect of dabigatran. (Funded by Boehringer Ingelheim; RE-VERSE AD ClinicalTrials.gov number, NCT02104947 .).

A highly regular fucosylated chondroitin sulfate from the sea cucumber Massinium magnum: Structure and effects on coagulation

A fucosylated chondroitin sulfate MM was isolated from the sea cucumber Massinium magnum. Structure of this polysaccharide was determined using chemical and NMR spectroscopic methods. The backbone of MM was shown to consist mainly of chondroitin sulfate E units with a small portion (about 10%) of chondroitin sulfate A fragments. Practically one type of branches Fuc3S4S attached to O-3 of GlcA residues was found in the polysaccharide molecules. The main repeating units of MM are →4)-[α-l-Fuc3S4S-(1→3)]-β-d-GlcA-(1→3)-β-d-GalNAc4S6S-(1→, whereas the minor repeating units are →4)-[α-l-Fuc3S4S-(1→3)]-β-d-GlcA-(1→3)-β-d-GalNAc4S-(1→. Anticoagulant activity of MM determined in APTT and TT tests was shown to be lower than that of heparin, but higher than that of enoxaparin. In the experiments with purified proteins MM effectively potentiated inhibition of thrombin and factor Xa by ATIII. Besides, MM did not induce platelets aggregation in platelets rich plasma.

Purification, partial characterization and bioactivity of sulfated polysaccharides from Grateloupia livida

Purification, preliminary characterization and bioactivity of polysaccharides from Grateloupia livida (GL) were investigated. Three water-soluble sulfated polysaccharide fractions (GLP-1, GLP-2 and GLP-3) were isolated and purified from the edible and medicinal red seaweed, Grateloupia livida (Harv.) Yamada by DEAE Sepharose CL-6B and Sephadex G-100 column chromatography, and chemical characterization was performed by HPGPC, GC-MS, FT-IR and SEM. In addition, anticoagulant activities were determined by activated partial thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT) using normal human plasma in vitro. The antioxidant activities against DPPH and ABTS⁺ radicals were evaluated and compared. The molecular weights of GLP-1, GLP-2 and GLP-3 were 39.5, 60.4 and 3.36kDa, respectively. Monosaccharide analysis revealed that three polysaccharide fractions were homopolysaccharides and comprised of galactose only. Anticoagulant assays indicated that crude GLP, and purified GLP-1 and GLP-2 effectively prolonged APTT and TT, but not PT. All polysaccharide fractions exhibited significant in vitro antioxidant activities in a dose-dependent manner. GLP-2 showed consistently better anticoagulant and antioxidant activities compared with GLP, GLP-1 and GLP-3. These results demonstrate that sulfated polysaccharides isolated from Grateloupia livida can serve as readily available alternative natural sources of anticoagulant and antioxidant agents.

Lupus Anticoagulant Testing: Diluted Russell Viper Venom Time (dRVVT)

Diluted Russell Viper Venom Time (dRVVT) has become the most popular test to detect Lupus Anticoagulant (LA). dRVVT is more sensitive than other global tests employed to detect LA and is not affected by inhibitors of factor VIII or IX. The test is most successfully implemented if you observe three steps in its execution: screening, mixing, and confirmatory studies. Interference due to the presence of heparin in tested plasma must be excluded by means of thrombin time (TT). The prior use of Vitamin K Antagonists (VKAs) or Non-vitamin K Oral Anticoagulants (NOACs) must also be evaluated by means of International Normalized Ratio, or specific tests, respectively.

[Renal function and plasma dabigatran level measured at trough by diluted thrombin time assay]

Dabigatran etexilate (direct thrombin inhibitor) is effective in preventing embolic stroke in patients with atrial fibrillation. It does not require laboratory control, but given the high renal elimination, its measurement in plasma is important in renal failure. The objectives of the study were to verify the analytical quality of the diluted thrombin time assay for measurement of dabigatran plasma concentration (cc), correlate cc with classic coagulation assays, prothrombin time (PT) and activated partial thromboplastin time (APTT), and evaluate them according to the creatinine clearance (CLCr). Forty plasma samples of patients (34 consecutive and 6 suspected of drug accumulation) receiving dabigatran at 150 (n = 19) or 110 (n = 21) mg/12 hours were collected. Blood samples were drawn at 10-14 hours of the last intake. Dabigatran concentration was determined by diluted thrombin time (HemosIl DTI, Instrumentation Laboratory (IL). PT and APTT (IL) were performed on two fotooptical coagulometers, ACL TOP 300 and 500 (IL). DTI presented intra-assay coefficient of variation < 5.4% and inter-assay < 6%, linearity range 0-493 ng/ml. Patients' cc: median 83 (4-945) ng/ml. Individuals with CLCr in the lowest tertile (22.6-46.1 ml/min) showed significantly higher median cc: 308 (49-945), compared to the average 72 (12-190) and highest tertile, 60 (4-118) ng/ml. Correlation between cc and APTT or PT were moderate, r2 = 0.59 and -0.66, p < 0.0001, respectively. DTI test allowed us to quantify plasma dabigatran levels, both in patients with normal or altered renal function, representing a useful tool in clinical situations such as renal failure, pre surgery or emergencies.

Poor comparability of coagulation screening test with specific measurement in patients receiving direct oral anticoagulants: results from a multicenter/multiplatform study

Essentials Prothrombin and partial thromboplastin time (PT/PTT) measure direct oral anticoagulants (DOACs). PT, PTT and specific tests for DOACs were performed on patients treated for atrial fibrillation. Normal PT/PTT don't exclude DOAC activity and their prolongation doesn't confirm DOAC action. The use of PT or PTT to evaluate DOAC activity could cause dangerous misinterpretations.

SUMMARY

Background Prothrombin time (PT) and activated partial thromboplastin time (APTT) have been proposed to measure the effect of oral anti-activated factor X (FXa) or anti-activated FII drugs, respectively. Aims To evaluate the relationships and responsiveness of PT and APTT versus direct oral anticoagulant (DOAC) concentrations measured with specific coagulation tests performed with different platforms in four Italian anticoagulation clinics. Methods Six hundred and thirty-five patients with atrial fibrillation participated in the study: 240 were receiving dabigatran, 264 were receiving rivaroxaban, and 131 were receiving apixaban. Blood was taken at trough and peak within the first month (15-25 days) of treatment. PT, APTT, diluted thrombin time (dTT) calibrated for dabigatran and anti-FXa calibrated for rivaroxaban or apixaban were determined. Results For dabigatran, the correlation between APTT and dTT ranged from r = 0.80 to r = 0.62. For rivaroxaban, the correlation between the anti-FXa assay and PT ranged from r = 0.91 to r = 0.73. For apixaban, the correlation between the anti-FXa assay and PT was lower than for the two other drugs (r = 0.81 to r = 0.54). Despite the above significant correlations, the responsiveness of PT or APTT was relatively poor. A discrepancy between global testing and DOAC plasma concentrations was shown in a considerable proportion of patients, depending on the platform and drug, with values ranging from 6% to 62%. Conclusions Overall, poor responsiveness of the screening tests to DOAC concentrations was observed. PT and APTT normal values cannot exclude DOAC anticoagulant activity, and PT or APTT prolongation is not always associated with DOAC anticoagulant effect as determined with specific tests.

Evidence Based Coagulation Monitors: Heparin Monitoring, Thromboelastography, and Platelet Function

The hemostatic management of patients undergoing cardiac surgery is a unique challenge. Since its inception, cardiopulmonary bypass (CPB) has required meticulous attention to maintaining adequate anticoagulation. New anticoagulants and alternative monitoring techniques present an opportunity to investigate potential advances in the area of anticoagulation for CPB. Hemostasis after CPB is still a vexing problem, and the addition of antiplatelet medication to the platelet defect already incurred during CPB has led to hemorrhagic complications in cardiac surgery. The two opposing processes of anticoagulation and hemostasis must be managed carefully and modified with respect to the patient's hematologic status and desired hemostatic outcome. Cardiac surgical patients consume a much larger fraction of perioperative blood transfusions than the percentage of the surgical population they represent. Thus, during CPB, careful attention must be paid to optimal anticoagulation, platelet quiescence, biocompatible circuitry and interventions, and to monitoring hemostasis. The multifactorial etiology of the CPB-induced hemostatic defect requires a multimodal approach to blood conservation and hemostasis monitoring, including heparin maintenance and sophisticated point-of-care hemostasis monitoring. Each technology has its own attributes and each may be suitable for different populations based upon the expected defects being measured. This article reviews the evidence supporting the use of point-of-care monitors in coagulation and hemostasis management in cardiac surgical patients.

[Atrial Septal Defect with Hereditary Deficiency of Antithrombin III]

A 41-year-old female with hereditary deficiency of antithrombin III (ATIII) was diagnosed with atrial septal defect( ASD) and scheduled for the closure of ASD. She had been taking warfarin since she suffered from deep vein thrombosis 10 years ago. Preoperative management of anticoagulation included discontinuation of warfarin, and supplementation of antithrombin with heparin infusion. On the day of operation, antithrombin activity was maintained above 80% by administering antithrombin, and closure of ASD was carried out under standard cardiopulmonary bypass support using heparin. Heparin infusion was continued with antithrombin supplementation until prothrombin time-international normalized ratio(PT-INR) recovered to around 2.5 with warfarin. Her intra-and postoperative courses did not show any thromboembolic events, and she was discharged 20 days after the surgery.

To measure or not to measure direct oral anticoagulants before surgery or invasive procedures

Patients on direct oral anticoagulants (DOAC) may need interruption of treatment before surgery or invasive procedures. Owing to their favorable pharmacokinetics, DOAC could be interrupted for a fixed number of days before surgery or invasive procedures without laboratory testing. However, there are a number of issues that raise concerns about the safety of this strategy. In contrast, laboratory testing prior to surgery or invasive procedures would provide a direct assessment of the residual drug concentration and minimize the risk of bleeding. This forum is aimed at discussing the pros and cons of the two strategies and fostering discussion on this important issue. Overall, the laboratory strategy appears superior in terms of patient safety and should be considered in patients undergoing surgical or invasive procedures.

NOAC monitoring, reversal agents, and post-approval safety and effectiveness evaluation: A cardiac safety research consortium think tank

Four non-vitamin K antagonist oral anticoagulants (dabigatran, rivaroxaban, apixaban, and edoxaban) have been approved in the United States for treatment of atrial fibrillation (AF) and venous thromboembolic disease. They have been as or more effective than the prior standards of care, with less fatal or intracranial bleeding, fewer drug and dietary interactions, and greater patient convenience. Nonetheless, the absence of the ability for clinicians to assess compliance or washout with a simple laboratory test (or to adjust dosing with a similar assessment) and the absence of an antidote to rapidly stop major hemorrhage or to enhance safety in the setting of emergent or urgent surgery/procedures have been limitations to greater non-vitamin K antagonist oral anticoagulant usage and better thromboembolic prevention. Accordingly, a Cardiac Research Safety Consortium "think tank" meeting was held in February 2015 to address these concerns. This manuscript reports on the discussions held and the conclusions reached at that meeting.

Anticoagulant Activity and Structural Characterization of Polysaccharide from Abalone (Haliotis discus hannai Ino) Gonad

In this study, we aimed at characterizing the structure and the anticoagulant activity of a polysaccharide fraction (AGP33) isolated from the gonads of Haliotis discus hannai Ino. AGP33 was extracted by enzymatic hydrolysis and purified by ion-exchange and gel-filtration chromatography. The backbone fraction of AGP33 (BAGP33), which appeared to contain of mannose, glucose and galactose, was prepared by partial acid hydrolysis. According to methylation and nuclear magnetic resonance (NMR) spectroscopy, the backbone of AGP33 was identified as mainly consisting of 1→3-linked, 1→4-linked, and 1→6-linked monosaccharides. AGP33 is a sulfated polysaccharide with sulfates occur at 3-O- and 4-O-positions. It prolonged thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT) compared to a saline control solution in a dosage-dependent manner. AGP33 exhibited an extension (p < 0.01) of APTT compared to the saline group at concentrations higher than 5 μg/mL. AGP33 exhibited higher anticoagulant activity than its desulfated product (AGP33-des) and BAGP33. The results showed that polysaccharide with higher molecular weight and sulfate content demonstrated greater anticoagulant activity.

[Comparison of the Intrab-batch Precisions and Results of 4 Tests by 2 Operation Modes of SysmexCA-7000 Blood Coagulometer]

OBJECTIVE

To evaluate the difference of 2 operation modes for patient plasma coagulation test and its intra-batch precision by using SysmexCA-7000.

METHODS

The SysmexCA-7000 blood coagulometer with agents, the normal and micro operation modes were respectively used to determine the prothrombin time (PT), fibringen (Fib), activated patial thromboplastine time (APTT) and thrombin time (TT) in 10 mixtures of multiple plasma samples, quality-control samples and 50 patient plasma samples, Among them, the 10 mixed samples and 2 quality-control plasma samples were tested for 10 times by every mode. The average level (̄X) of PT, Fib, APTT and TT, standard deviation (S) and intra-batch precision (coefficient of variation CV%) were respectively calculated. The intra-batch precision and coagulation results under 2 mode operations were analyzed statistically.

RESULTS

There was significantly statistical difference (P < 0.001) for intra-batch CVs between 2 mode for APTT, Fib, PT and TT with a level of 0.53%-1.58%, 0.72%-2.08%, 0.51%-1.37%, 0.58%-1.60% and Normal mode with 1.17%-2.10%, 1.10%-2.43%, 0.88%-1.99%, 1.05%-1.98%, respectively. APTT, PT and Fib of 50 patient plasma samples under micro mode operations were statistically different from normal mode, but TT was not different between 2 modes.

CONCLUSION

The micro mode detection is more accurate and precise than that of normal mode by using SysmexCA-7000 blood coagulometer.

[State of homeostasis under administration of bear fat in rats with exogenous and endogenous thrombinemia]

In experimental studies on 448 rats treated with bear fat diet (0.08 ml/100 g body weight), the nature and mechanisms of influence of this additive on the process of blood coagulation in experimental thromboplastinemia of different origin has been studied. As a result of intravenous injection in the jugular vein of a suspension of thrombin (exog­enous thrombinemia) all clothingsee tests lengthened in the control animals (p<0.05): prothrombin time by 11.1%, activated partial thromboplastin time - by 13.4%, thrombin time by 16.8%. Fibrinogen fell by 1.9 fold, that was accompanied by increase of the level of soluble fibrin monomer complexes and reduce of activity of antithrombin III by 20.2%. At the same time severe thrombocytopenia developed with a relative increase in the num­ber of activated forms (by 73.1%). Consumption coagulopathy was also observed in rats treated with bear fat, but the potential of hemostatic cascade and anticoagulation system remained high (judging by the tests PTV, thrombin time and content of antithrombin III). Under endogenous thromboplastinemia caused by combined stress (hypothermia + physi­cal activity) in animals of the control group on the background of the shortening of the APTT (by 24.9%) and PTV (16.8%), RCMP concentration increased by 52% and activity of antithrombin III increased compensatory. There was an increase of platelet count, due to the activated forms. To 3 h signs of hypocoagulation aggravated even more. In animals treated with bear fat, the results of clothing tests did not differ from the original figures, and by 3 h, the majority of the indicators have reached their original values. The increase in platelet count has not been observed.

Effect of standardized perioperative dabigatran interruption on the residual anticoagulation effect at the time of surgery or procedure

ESSENTIALS: Anticoagulants need to be stopped preprocedure so there is little or no remaining anticoagulant effect. We assessed the residual anticoagulant effect with standardized interruption for patients on dabigatran. With this protocol, 80-86% of patients had no residual anticoagulant effect at the time of a procedure. A standardized perioperative dabigatran protocol appears to be safe, but requires further study.

BACKGROUND

In patients taking dabigatran who require treatment interruption for a surgery/procedure, a sufficient interruption interval is needed so that there is little or no residual anticoagulant effect at the time of the surgery/procedure.

METHODS

A prospective cohort study of patients receiving dabigatran (110 mg or 150 mg twice daily) who required an elective surgery/procedure and received a standardized dabigatran interruption protocol based on surgery/procedure bleeding risk and renal function was performed. Before the surgery/procedure, a blood sample was taken for measurement of the prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), and dilute thrombin time (dTT). We determined the proportion of all patients and those having a high bleeding risk surgery/procedure with normal coagulation test results at the time of the surgery/procedure. The APTT and dTT were considered to be most likely to reflect a dabigatran anticoagulant effect. Patients were followed up for 30 days postprocedure to assess for bleeding and thromboembolism.

RESULTS

One hundred and eighty-one patients were studied: 118 with low bleeding risk, and 63 with high bleeding risk. For all patients, the proportions with normal PT, APTT, TT dTT levels were 92.8%, 79.6%, 33.1%, and 80.7%, respectively. In patients with high bleeding risk, the proportions with normal PT, APTT, TT dTT levels were 93.7%, 85.7%, 57.1%, and 87.3%, respectively. During follow-up, there was one (0.6%) major bleed, there were nine (5.0%) minor bleeds, and there was one (0.6%) transient ischemic attack.

CONCLUSIONS

In patients receiving dabigatran who require an elective surgery/procedure, a standardized interruption protocol yielded 80-86% of patients with no residual anticoagulant effect at the time of surgery/procedure, and with a low incidence of bleeding.

Recent guidelines and recommendations for laboratory assessment of the direct oral anticoagulants (DOACs): is there consensus?

A new generation of antithrombotic agents, which are conventionally known as direct oral anticoagulants (DOACs), have recently emerged and are continuing to be developed. These provide direct inhibition of either thrombin (factor IIa; FIIa) or activated factor X (FXa) and currently include dabigatran (FIIa inhibitor) and rivaroxaban, apixaban, and edoxaban (FXa inhibitors). The dogma that DOACs do not require laboratory monitoring is countered by ongoing recognition that laboratory testing for drug effects is needed in many situations. In this review, we summarize the background to establishment of DOACs, assess which tests were found to be useful to screen for or quantitate drug effects/levels, and then review published guidelines/recommendations to assess concordance. In brief, (a) for the anti-FIIa agent dabigatran, the recommended screening assays are activated partial thromboplastin time (APTT) and/or thrombin time (TT), and the quantitative assays (using a dabigatran standard) are dilute TT/direct thrombin inhibitor assay (Hemoclot thrombin inhibitor) or an ecarin-based assay such as the ecarin clot time (ECT); (b) for the anti-FXa agent rivaroxaban, the recommended screening assay is the prothrombin time (PT), but this was not endorsed by all guidelines, and the quantitative assay (using a specific rivaroxaban standard) is an anti-FXa assay; (c) for the anti-FXa agent apixaban, the general insensitivity of PT and APTT prevented most groups from providing recommendation, and instead there was generalized support for direct quantitative assessment using anti-FXa assays and specific apixaban standard; (d) there is insufficient data for other direct anti-FXa agents and limited guidance in the literature.

Structural Features and Anti-coagulant Activity of the Sulphated Polysaccharide SPS-CF from a Green Alga Capsosiphon fulvescens

Previously, we reported that the sulphated polysaccharides (SPS)-CF, a water-soluble polysaccharide isolated and purified from Korean green alga Maesaengi (Capsosiphon fulvescens, Chlorophyta), is a glucuronogalactomannan based mainly on the monosaccharide composition determined by high-performance liquid chromatography (HPLC) analysis after 1-phenyl-3-methyl-5-pyrazolone (PMP) labelling of sugars in the acid (trifluoroacetic acid (TFA)) hydrolyzates of SPS-CF, which showed mannose (55.4 mol %), galactose (25.3 mol %) and glucuronic acid (16.3 mol %) as major sugars (Na et al., Int Immunopharmacol 10:364-370, 2010). However, the results of the present study re-performed for monosaccharide composition of this polysaccharide using, in addition to HPLC of PMP-labelled sugars, other separation methods, i.e. high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD), gas chromatography with flame ionising detection (GC-FID) and thin-layer chromatography (TLC), clearly demonstrated that the most prominent neutral monosaccharides of SPS-CF are xylose (38.6-49.4 mol %) and rhamnose (39.6-45 mol %), while mannose and galactose are present at a much lesser extent or in negligible amount. These extensive monosaccharide analyses, correlation nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) measurements confirmed the sulphated glucuronorhamnoxylan (ulvan) type of SPS-CF polysaccharide, whose backbone is composed of alternating sequence of 4-linked L-rhamnose-3-sulphate and D-xylose residues (ulvobiose U3s) carrying monomeric D-glucuronic acid or D-glucuronic acid-3-sulphate on O-2 of some L-rhamnose-3-sulphate units as the side chains. The SPS-CF exhibited significant in vitro anti-coagulant activity by which the activated partial thromboplastin time (aPTT) and thrombin time (TT) were significantly prolonged. The results of this study demonstrated that the ulvan SPS-CF isolated from Korean Maesaengi C. fulvescens can be considered a potential anti-coagulant agent.

Application Of Phenol/Amine Copolymerized Film Modified Magnesium Alloys: Anticorrosion And Surface Biofunctionalization

Magnesium metal as degradable metallic material is one of the most researched areas, but its rapid degradation rate restricts its development. The current anticorrosion surface modification methods require expensive equipment and complicated operation processes and cannot continue to introduce biofunction on modified surface. In this study, the GAHD conversion coatings were fabricated on the surface of magnesium alloys (MZM) by incubating in the mixture solution of gallic acid (GA) and hexamethylenediamine (HD) to decrease the corrosion rate and provide primary amines (-NH2), carboxyl (-COOH), and quinone groups, which is supposed to introduce biomolecules on MZM. Chemical structures of the MZM-GAHD and MZM-HEP-GAHD were explored by analyzing the results of FTIR and XPS comprehensively. Furthermore, it was proved that the heparin (HEP) molecules were successfully immobilized on MZM-GAHD surface through carbodiimide method. The evaluation of platelet adhesion and clotting time test showed that MZM-HEP-GAHD had higher anticoagulation than MZM-GAHD. Through electrochemical detection (polarization curves and electrochemical impedance spectroscopy Nyquist spectrum) and immersion test (Mg(2+) concentration and weight loss), it was proved that compared to MZM, both the MZM-GAHD and MZM-HEP-GAHD significantly improved the corrosion resistance. Finally, in vivo experimentation indicated that mass loss had no significant difference between MZM-1:1, MZM-HEP-1:1, and MZM. However, the trend still suggested that MZM-1:1 and MZM-HEP-1:1 possessed corrosion resistance property.

Clinical Significance of Preoperative Thrombin Time in Patients with Esophageal Squamous Cell Carcinoma following Surgical Resection

Background

Noninvasive tools for the prognosis of ESCC are urgently needed. To this end, serum coagulation tests have been researched in some cancers, but the prognostic value of the TT in ESCC has not been described.

Methods

The levels of pre-treatment serum coagulation markers (including the PT, APTT, PTA, INR, fibrinogen level, TT and PLT) were retrospectively analyzed in 204 patients with ESCC who underwent surgical resection at our department and in 200 healthy controls, and the two groups were compared. The prognostic significance of the coagulation tests was then determined with univariate and multivariate cox hazard analyses in patients with ESCC.

Results

Compared with those in normal controls, the PT, APTT, and fibrinogen levels were significantly increased, whereas the TT values significantly decreased in the 204 ESCC patients. The TT directly correlated with the 5-year survival rate, not only in the entire ESCC cohort (p = 0.023) but also in the subgroups stratified according to the T and N classifications and metastasis. Conversely, the other tests were not independent prognostic factors for ESCC. Of the clotting markers, the TT inversely correlated with the fibrinogen level (p = 0.005).

Conclusions

The 5-year survival was shorter in ESCC patients exhibiting decreased pre-treatment TT values. Thus, the serum TT may be a clinical prognostic factor for ESCC patients.

Comparative studies of pharmacokinetics and anticoagulatory effect in rats after oral administration of Frankincense and its processed products

ETHNOPHARMACOLOGICAL RELEVANCE

Frankincense (FRA), Ruxiang, is the resin of Boswellia carterii Birdw and Boswellia bhaw-dajiana Birdw which has been used for centuries as formulas to improve the circulation and to relieve pain against carbuncles. Stir-fried Frankincense (SFF) and vinegar processed Frankincense (VPF) are two major processed Frankincense, and the processing procedures reportedly enhance the curative efficacy or reduce the side effects of FRA. This paper describes the comparisons in plasma pharmacokinetic behaviors of 11-keto-β-boswellic acid (KBA) and 3-acetyl-11-keto-β-boswellic acid (AKBA) in FRA and its processed products, and their effects on coagulation factors and blood clotting tetrachoric, using an acute cold blood-stasis animal model after oral administration of FRA, SFF, and VPF.

MATERIALS AND METHODS

For pharmacokinetic study, Sprague-Dawley (SD) rats were randomly divided into three groups, including group FRA, group SFF and group VPF. And the plasma samples were analyzed by HPLC. For study of anticoagulatory effect, SD rats were randomly divided into six groups, including control, acute cold blood-stasis model, Fu-fang-dan-shen tablet- (0.75g/kg), FRA-, SFF-, and VPF-treated (2.7g/kg) groups, respectively. The serum contents of thrombin-antithrombin complex (TAT), D-dimer (D-D), and prostacyclin (PGI2) of each group were measured by ELISA. The values of prothrombin time (PT), thrombin time (TT), activated partial thromboplastin time (APTT) and fibrinogen (FIB) were also assessed by hematology analyzer.

RESULTS

Significantly increased levels of Cmax, AUC, T1/2, and MRT were found in rats treated with the processed products. In addition, decreased levels of D-D and TAT and increased contents of PGI2 were observed in rats given FRA and its processed products, compared with that of the model group. Moreover, VPF improved anticoagulation more than SFF in the animals.

CONCLUSIONS

The observed improvement of anticoagulation by processed FRA may result from the increased absorption and bioavailability of triterpenoids.

[Study on antiplatelet and antithrombin activitives and effective components variation of Puhuang-Wulingzhi before and after compatibility]

The changes of bioactive constituents were analyzed for Puhuang-Wulingzhi before and after compatibility and the antiplatelet and antithrombin activitives were evaluated in order to elucidate the scientific and reasonable of Puhuang-Wulingzhi compatibility. UPLC-QTOF-MA-Markerlynx, principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis were used for data analysis and tracking changes of chemical composition during the decocting process. In vitro platelet aggregation induced by ADP, thrombin time(TT) and prothrombin time (PT) were investigated for Puhuang-Wulingzhi before and after compatibility. The results showed that significant differences were found between the mixed decoction and codecoction of Wulingzhi and Puhuang. Five compounds changed obviously were identified as typhaneoside, naringenin, isorhamnetin-3-O-ruinoside, quercetin-3-O-neohesperidoside, kaempferol-3-O-neohesperidoside. The codecoction, comparing with the single decoction, was more significant in antiplatelet aggregation and could prolong thrombin time. In the same crude drug dose, the thrombin time (TT) elongation were greater. These data could provide references for elucidation of bioactive components for this herb pair.

Effect of Acute Normovolemic Hemodilution Combined with Controlled Low Central Venous Pressure on Blood Coagulation Function and Blood Loss in Patients Undergoing Resection of Liver Cancer Operation

BACKGROUND/AIMS

This paper aims to investigate the effect of acute normovolemic hemodilution (ANH) used with controlled low central venous pressure (LCVP) technology on perioperative bleeding and coagulation in hepatocellular carcinoma operation patients.

METHODOLOGY

A total of 60 cases undergoing hepatic resection operation were randomly divided into the control group, LCVP group (Group II), and ANH + LCVP group (Group III). The changes of hemodynamic indexes at different time points in each group were observed and recorded, along with the volume of allogenous blood transfusion and the number of patients undergoing allogenous blood transfusion.

RESULTS

Compared with Group I (control), there was evident reduction of the bleeding volume, allogenic blood transfusion volume, and number of patients undergoing allogenic blood transfusion in Groups II and III.

CONCLUSION

The application of ANH combined with LCVP in hepatic resection can evidently reduce intraoperative hemorrhages and homologous blood transfusions; moreover, it has no significant adverse effect on the coagulation function.