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Innovations in Noninvasive Instrumentation and Measurements
Published in Robert B. Northrop, Non-Invasive Instrumentation and Measurement in Medical Diagnosis, 2017
INR is defined as INR≡{PTtestPTnormal}ISI, where the ISI exponent is the International Sensitivity Index, usually between 1 and 2. PTtest is the measured prothrombin (clotting) time, PTnormal is the mean prothrombin time for normal persons not under warfarin medication. Prothrombin time is the time it takes plasma to clot after addition of tissue factor (cf. Glossary).
In vitro Evaluation
Published in Raj Bawa, János Szebeni, Thomas J. Webster, Gerald F. Audette, Immune Aspects of Biopharmaceuticals and Nanomedicines, 2019
The prothrombin time (PT) test measures the activation of coagulation by the extrinsic or tissue factor. For the assessment of the coagulation time, once a sample is placed into the coagulometer, phospholipid calcium thromboplastin is added and the coagulation time is automatically assessed. Normal values for healthy humans are in the range 12–15 s.
Heparinized PCL/keratin mats for vascular tissue engineering scaffold with potential of catalytic nitric oxide generation
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Xiuzhen Wan, Yanfang Wang, Xingxing Jin, Pengfei Li, Jiang Yuan, Jian Shen
APTT, PT and TT were applied to evaluate the anticoagulant potential in vitro. According to Figure 4, the APTT value of PCL was a bit longer than that of PPP, indicating its good blood compatibility. Regarding to PCL/keratin mats, the APTT value was significantly prolonged because S-carboxymethyl keratin was introduced. It was well known that the hydrophilicity of carboxyl groups were benefit to blood compatibility. In the term of heparinized mats, the APPT value was prolonged by almost 43 s compared with PPP. It indicated the conjugated heparin effectively impacts the intrinsic coagulation pathway [42]. Prothrombin time (PT) was used to detect the coagulation time in the extrinsic pathway. PT value for heparinized PCL/keratin mats just only prolonged for 1 s (Figure 4b). TT was used to test the clot formation time for the thrombin conversion of fibrinogen into insoluble fibrin protein. The longer TT clotting time suggested the slower conversion speed, resulting in thrombus inhibition. TT clotting time for heparinized PCL/keratin mats was prolonged about 3 s (Figure 4c).