Thrombin heparin affecting

Each of these tests is also affected by the final common pathway, the endpoint of which is tested by the thrombin time. This tests the formation of a fibrin clot by the addition of exogenous thrombin and calcium. It is sensitive to the level of endogenous fibrinogen and to the presence of inhibitors of thrombin (heparin, PDFs). 

M Lackmann, et al. Radioimmunoassay for the detection of active site specific thrombin inhibitors in biological fluids—Heparin affects the binding of hirudin to alpha-thrombin. Thromb Res 63 609, 1991. 

Polyanions snch as heparin bind to the thrombin and could affect the binding affinity of proteins to the aptamer. To verify this hypothesis, we studied the interaction of thrombin with DNA aptamer at molar ratios of thrombin to heparin 1 1, 1 3, and 1 10. The thrombin, heparin, or their complexes were added to the buffer stepwise from a stock solution, and the charge transfer was measnred... 

LMWHs are formed by various methods of fractionation or depolymerization of polymeric heparin (Table 7.1). Although they are enzymatically derived from UFH, they have a different site of achon and can be administered subcutaneously. LMWHs exert their anhcoagulant effect by inhibiting factor Xa and augmenting tissue-factor-pathway inhibitor, but minimally affect thrombin or factor Ila (Figs. 7.1 and 7.2)." Thus, the PTT, a measure of antithrombin (anh-factor Ila) achvity, is not used to measure the achvity of LMWHs. 

Tincture of the dried seed, on agar plate at a concentration of 30 p,L/disc, was inactive on Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Extract of 10 g plant material in 100 mL ethanol was used b Anticoagulation activity. Serpin BSZx (an inhibitor of trypsin and chemotrypsin) inhibited thrombin, plasma kallikrein, factor Vlla/tissue factor, and factor Xa at heparin-independent association rates. Only factor Xa turned a significant fraction of BSZx over as substrate. Activated protein C and leukocyte elastase were slowly inhibited by BSZx, whereas factor Xlla, urokinase and tissue type plasminogen activator, plasmin and pancreas kallikrein, and elastase were not or only weakly affected. Trypsin from Fusarium was not inhibited, while interaction with subtilisin Carlsberg and Novo was rapid, but most BSZx was cleaved as a substrate L... 

Table 1 demonstrates that high lytic activity is displayed by the complexes of thrombin and fibrinogen as well as by that of heparin and plasmin. These complexes, as was shown in Ref.35), affect the unstabilized fibrin only and supress simultaneously the activity of the fibrin-stabilizing factor. Qualitatively similar results were observed in in vivo experiments. 

The data on protein adsorption as affected by immobilized heparin is quite contradictory. In Refs.114> and115), serum albumin was shown to be predominantly adsorbed by the HCP, whereas in the majority of other works the observed dependence was the opposite. Table 14 compiles the results of the studies of the absorption of plasma proteins by HCP of two different types 64). Such thrombogenic proteins as fibrinogen and thrombin are seen to be the ones adsorbed most. 

Argatroban is a small molecule thrombin inhibitor that is FDA approved for use in patients with heparin-induced thrombocytopenia (HIT) with or without thrombosis and coronary angioplasty in patients with HIT. It, too, has a short half-life, is given by continuous intravenous infusion, and monitoring is done by aPTT. Its clearance is not affected by renal disease but is dependent on liver function. The drug requires dose reduction in patients with liver disease. Patients on argatroban will demonstrate elevated INRs because of test interference, rendering the transition to warfarin difficult. 

The thrombin time measures the conversion of flbrinogen to flbrin and is affected by quantitative and qualitative abnormalities of flbrinogen and the presence of thrombin inhibitors or flbrinogen degradation products. The thrombin time measures the time required for the formation and the appearance of the fibrin clot after thrombin is added to plasma. It may be used to monitor the effect of systemic fibrinolytic therapy and can be modified for monitoring heparin therapy. 

Answer B. Heparin forms aril complex with antithrombin III and enhances its activity from 100- to 1,000-fold. The peak effect of heparin is not reached for several hours, and continued use over several days has no effect on thrombin levels. Prostacyclin (PGI2) is a platelet inhibitor, and its levels are not affected by heparin,... 

Heparin and heparin-like compounds are available in a variety of molecular weight fractions. The lower molecular weight heparins are not able to bind both antithrombin III and thrombin simultaneously, which is necessary for the inactivation of thrombin. These drugs, consequently, affect the actions of factors lXa and Xa, rather than thrombin. 

Heparin and warfarin are anticoagulants that affect activation or formation of proteins in the clotting cascade. Lepirudin is an inhibitor of thrombin, and aminocaproic acid is an inhibitor, not an activator, of fibrinolysis and the conversion of plasminogen to plasmin. Reteplase is the only thrombolytic drug listed. The answer is (D). 

In this chapter the focus is on the use of electrochemical indicators and of the TSM method for the study of protein-aptamer interactions. Aptamers sensitive to thrombin are used for the fabrication of biosensors. Attention is given to methods of immobilization of aptamers to a solid support and how this affects the interaction of thrombin with the aptamer. The effects of aptamer structure, of the presence of the thrombin inhibitor heparin, and of the ions and pH on the binding properties of aptamer are presented. The advantages of electrochemical indicators and the TSM method for the detection of thrombin-aptamer interactions are demonstrated. 

Crosslinked poly(amido-amines) are by themselves inert towards the coagulation parameters of blood. We have demonstrated that they do not affect recalcification time, prothrombin time, thrombin time, or fibrinogen content of unheparinized blood, at any speed of filtration from 2 to 200 ml/min. Their biological effects and physical and chemical properties lead us to visualize their being used to make molecular filters capable of de-heparinizing blood. Application of the filters in clinical apparatus can be envisaged (21-23). 

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