Components of the hemostatic

Primary and even tertiary structures are now known for many of the hemostatic system proteins. Gene structures have been identified for all of the known components of the hemostatic system. Databases listing mutations and their related hemorrhagic or thrombotic risks are growing rapidly. For many reactions, the molecular mechanisms responsible for the properties of the hemostatic... 

Estrogen therapy has been linked to changes in the concentrations of several components of the hemostatic system. However, there are no changes in components of the procoagulant, anticoagulant, or fibrinolytic system that can be clearly linked to an increase in risk of thromboembolic disease sometimes associated with estrogen therapy. 

Although the many components of the hemostatic system inevitably create a high level of complexity, the functional and structural similarities between and among the different molecules permit the simplification described above. Simplification can be obtained by representing many of the molecules as ellipses, the two-dimensional representations of the generally ellipsoid shapes of the molecules in solution (see Figure 36-9 below). However, the common motifs and similar proteinase domain structures can be presented even more simply in the form of bar diagrams, which are usually used in the descriptions of reactions that follow. 

A 30-year-old man with recurrent thrombosis is referred to you for diagnosis. The PT and APTT results determined on his freshly drawn plasma sample are 10.1 s (normal 10-12 s) and 18 s (normal 20-32 s). Which components of the hemostatic system would you initially suspect as being... 

First, it was determined whether or not aerogel samples would induce platelet activation upon contact. To investigate this, washed platelets were incubated with aerogel samples for up to 6 h. The expression of phosphatidylserine (PS) and P-selectin (CD-62P) was measured to determine how platelets responded to aerogel contact. Platelets are a critical component of the hemostatic system and play a salient role in clot formation. 

Adhesion of platelets onto a damaged vascular sur ce is the primary event in the formaticHi ofd hemostatic plug. For perfect hemostatic performance, this initial adhesion step should be followed by further deposition of platelets onto the initial adherent layer rmtil an effective microthrombi is formed at the site of damage. Formation of s hemostatic plug is the result of a well recognized series of interactions among platelet glycoproteins, plasma adhesive proteins and components of the subendothelium. 

Accepting the above limitations of our knowledge of the true in vivo reaction sequence, a series of clot-endpoint tests has been used for many years to determine the hemostatic balance in any patient. The first, known as the thrombin time test, can be used to measure the concentration of fibrinogen (B15). The second assay, the activated partial thromboplastin time test (APTT), measures the components of the intrinsic pathway (M4). These include the serine proteases (Factors XII, XI, X, and II), the cofactors (Factors VIII and V) and again, fibrinogen. Most of the hereditary deficiencies... 

W.D. Spotnitz, S. Burks, Hemostats, sealants, and adhesives components of the surgical toolbox. Transfusion 48 (2008) 1502-1516. 

Spotnitz, W.D., Burks, S. State-of-the-art review hemostats, sealants, and adhesives II update as well as how and when to use the components of the surgical toolbox. CUn. Appl. Thromb. Hemost. 16(5), 497-514 (2010)... 

In 1998, the FDA approved fibrin sealant for three specific indications. These include hemostasis at the time of cardiac surgical operations [8] (Fig. 2) as well as at the time of operative procedures to treat splenic trauma. The application of the fibrin sealant which consists of normal biologic components in the body s clotting cascade creates a localized clot which further enhances inherent clotting ability. Although approved for these specific hemostatic indications only, fibrin sealant is useful as a hemostat in a wide variety of off-label clinical situations as well [9,10]. These include such applications as hemostasis for liver trauma or resection [11], vascular anastomoses [12], tonsillectomy [13], peripheral joint replacement [14], dental extractions [15], and bum debridement [16]. 

The essential and most thoroughly defined role of vitamin K is as a cofactor to vitamin K-dependent carboxylase, an enzyme necessary for the posttranslational conversion of specific glutamyl residues in target proteins to y-carboxygiutamyl (Gla) residues. This y-carboxylation increases the affinity of these proteins for calcium. The antihemorrhagic function of vitamin K depends upon the formation of the Gla proteins prothrombin (factor II), proconvertin (factor VII), plasma thromboplastin component (factor IX), and Stuart factor (factor X), which together with two other hemostatic vitamin K-dependent proteins, proteins C and S and Ca A initiate a process to form... 

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