1251-Antithrombin III

Affinity chromatography is used in the preparation of more highly purified Factor IX concentrates (53—55) as well as in the preparation of products such as antithrombin III [9000-94-6] (56,57). Heparin [9005-49-6], a sulfated polysaccharide (58), is the ligand used most commonly in these appHcations because it possesses specific binding sites for a number of plasma proteins (59,60). 

Factor VIII, immunoglobulin, and albumin are all held as protein precipitates, the first as cryoprecipitate and the others as the Cohn fractions FI + II + III (or FII + III) and FIV + V (or FV), respectively (Table 7, Fig. 2). Similarly, Fractions FIVj + FIV can provide an intermediate product for the preparation of antithrombin III and a-1-proteinase inhibitor. This abiUty to reduce plasma to a number of compact, stable, intermediate products, together with the bacteriacidal properties of cold-ethanol, are the principal reasons these methods are stiU used industrially. 

IV, a-l-proteinase inhibitor antithrombin III IgM ceruloplasmin a- and P-globutins a-tipoprotein albumin 5-10... 

Alpha-1-proteinase inhibitor and antithrombin III are used to treat people with hereditary deficiencies of these proteins. Both can be recovered from Cohn Fraction IV (Table 7) using ion-exchange chromatography (52) and affinity chromatography (197), respectively. Some manufacturers recover antithrombin III directiy from the plasma stream by affinity adsorption (56,198,199). 

Schreuder, H.A., et al. The intact and cleaved human antithrombin III complex as a model for serpin-proteinase interactions. Nature (Struct. Biol.)... 

Anion-exchangers 145, 147 Anti-Rh sera 171 Antibodies, antitetanus 144 Antitetanus antibodies 144 Antithrombin III 145 Assembly systems, molecular 52... 

Heparin is an important anticoagulant. It binds with factors IX and XI, but its most important interaction is with plasma antithrombin III (discussed in Chapter 51). Heparin can also bind specifically to lipoprotein lipase present in capillary walls, causing a release of this enzyme into the circulation. 

Four naturally occurring thrombin inhibitors exist in normal plasma. The most important is antithrombin III (often called simply antithrombin), which contributes approximately 75% of the antithrombin activity. Antithrombin III can also inhibit the activities of factors IXa, Xa, XIa, Xlla, and Vila complexed with tissue factor. a2-Macroglobulin contributes most of the remainder of the antithrombin activity, with heparin cofactor II and aj-antitrypsin acting as minor inhibitors under physiologic conditions. 

The endogenous activity of antithrombin III is gready potentiated by the presence of acidic proteoglycans such as heparin (Chapter 48). These bind to a specific cationic site of antithrombin III, inducing a conformational change and promoting its binding to... 

Anticoagulant combines with antithrombin III to inhibit thrombin... 

An important namral inhibitor of coagulation is antithrombin III genetic deficiency of this protein can result in thrombosis. 

Protein C, protein S, antithrombin III, activated protein C resistance, lipoprotein(a) anticardiolipin antibodies, lupus anticoagulant, prothrombin gene mutation 20210a... 

Alphafoetoprotein, Ancrod, Anti-D Immunoglobulin, Antithrombin III total, Apolipoprotein B, Haemoglobin A2 and F Lysate, Heparin, Protamine Protein C, Fibrinogen, Plasmin a-Thrombin, Antithrombins, (3-Thromboglobulin, Haemiglo-bincyanide... 

There are various inhibitors within the coagulation system that counterregulate activation of the coagulation cascade. Among them, antithrombin III (AT-III) and protein C (PC) are the most important (SI). AT-III binds in the presence of heparin the activated factors F-IXa, F-Xa, and F-IIa (thrombin). PC is activated by a complex formed between thrombin and thrombomodulin, a surface protein of endothelial cells. Once activated, PC in the presence of protein S (PS) specifically degrades activated factors F-Va and F-VIIIa. PC decreases in the course of sepsis in relation to the severity of the condition (L15). Experimental studies have... 

With respect to both the coagulation and fibrinolytic cascade systems, in 28 patients who developed septic shock a relation was found between lowered plasma levels of F-XII and antithrombin III and elevated levels of PAI-1 and thrombin-antithrombin III complexes at the diagnosis of sepsis and the severity of disease, expressed according to the APACHE II scoring system (L7). Nevertheless, administration of inhibitors of coagulation or enhancement of fibrinolysis did not improve the outcome in patients with sepsis (B35). 

Antithrombin III. AT-III administration holds some promise because it inhibits a number of activated coagulation factors F-XIa, F-IXa, F-Xa, and thrombin. There are, however, no data to support the use of heparin. Although a... 

Nesheim M., Blackburn M. N., Lawler C. M., Mann K. G. Dependence of antithrombin III and thrombin binding stoichiometries and catalytic activity on the molecular weight of affinity purified heparin. J Biol Chem 1986 261,3214-21. 

Atha, D.H., Brew, S.A., and Ingham, K.C. (1964) Interactions and thermal stability of fluorescent labeled derivatives of thrombin and antithrombin III. Biochim. Biophys. Acta 785, 1. 

Although the product has proven to be an effective (and relatively inexpensive) anticoagulant, it does suffer from a number of clinical disadvantages, including the need for a cofactor (antithrombin III) and poorly predictable dose responses. Despite such disadvantages, however, heparin still enjoys widespread clinical use. 

Laboratory tests for hypercoagulable states should be done only when the cause of the stroke cannot be determined based on the presence of well-known risk factors. Protein C, protein S, and antithrombin III are best measured in steady state rather than in the acute stage. Antiphospholipid antibodies are of higher yield but should be reserved for patients aged less than 50 years and those who have had multiple venous or arterial thrombotic events or livedo reticularis. 

Thrombogenic mutations (e.g., factor V Leiden, protein C or S deficiency, antithrombin III... 

Jordan VC, Fritz NF, Tormey DC (1987a) Long-term adjuvant therapy with tamoxifen effects on sex hormone binding globulin and antithrombin III. Cancer Res 47 4517-4519... 

---