Argatroban as an anticoagulant for both hematologic and chemical tests

Generation of Rapid and High-Quality Serum by Recombinant Prothrombin Activator Ecarin (RAPClot™)

We recently reported the potential application of recombinant prothrombin activator ecarin (RAPClot™) in blood diagnostics. In a new study, we describe RAPClot™ as an additive to develop a novel blood collection prototype tube that produces the highest quality serum for accurate biochemical analyte determination. The drying process of the RAPClot™ tube generated minimal effect on the enzymatic activity of the prothrombin activator. According to the bioassays of thrombin activity and plasma clotting, γ-radiation (>25 kGy) resulted in a 30-40% loss of the enzymatic activity of the RAPClot™ tubes. However, a visual blood clotting assay revealed that the γ-radiation-sterilized RAPClot™ tubes showed a high capacity for clotting high-dose heparinized blood (8 U/mL) within 5 min. This was confirmed using Thrombelastography (TEG), indicating full clotting efficiency under anticoagulant conditions. The storage of the RAPClot™ tubes at room temperature (RT) for greater than 12 months resulted in the retention of efficient and effective clotting activity for heparinized blood in 342 s. Furthermore, the enzymatic activity of the RAPClot™ tubes sterilized with an electron-beam (EB) was significantly greater than that with γ-radiation. The EB-sterilized RAPClot™ tubes stored at RT for 251 days retained over 70% enzyme activity and clotted the heparinized blood in 340 s after 682 days. Preliminary clinical studies revealed in the two trials that 5 common analytes (K, Glu, lactate dehydrogenase (LD), Fe, and Phos) or 33 analytes determined in the second study in the γ-sterilized RAPClot™ tubes were similar to those in commercial tubes. In conclusion, the findings indicate that the novel RAPClot™ blood collection prototype tube has a significant advantage over current serum or lithium heparin plasma tubes for routine use in measuring biochemical analytes, confirming a promising application of RAPClot™ in clinical medicine.

Tissue factor pathway inhibitor as a universal anticoagulant for use in clinical laboratory tests

Tissue factor pathway inhibitor (TFPI) is a protease inhibitor of extrinsic coagulation. The present study investigates the possibility of utilizing TFPI as a universal anticoagulant in clinical laboratory tests. The optimal concentration of TFPI for use in clinical laboratory tests was found to be 1 microl TFPI/ml blood (100 mmol TFPI/ml blood); the subsequent analyses were conducted at this concentration. In hematological tests, complete blood cell count and differential white blood cell count were done with an automatic blood analyzer. The results except for platelet and white blood cell counts were similar for ethylenediaminetetraacetic acid (EDTA)-treated and TFPI-treated samples. The effects of TFPI on platelet count were more pronounced when blood samples were stored at 4 degrees C than at room temperature. The effects of TFPI on cell morphology were evaluated by spreading blood samples into thin films and applying a Giemsa stain. The results showed that TFPI did not alter the morphology of blood cells. An automatic biochemical analyzer performed seventeen basic biochemical tests on serum samples and TFPI-treated plasma samples. The results of seventeen tests were comparable between TFPI-treated samples and EDTA-treated samples. The prothrombin time for TFPI-treated plasma samples was longer than that for citrated plasma samples. Nonetheless, in activated partial thromboplastin time tests, the addition of the reagent caused turbidity and partial coagulation, thus demonstrating that TFPI is not suitable for this assay. These findings suggest that although some tests cannot be performed with TFPI, this compound may be useful as a universal anticoagulant in the future.