Blood, viii

Stern, N. S., Factors affecting the coagulation time of blood. VIII. The influence of certain metals and the electric current. Am. J. Physiol. 40, 186-193 (1916). 

Factors I, II, III, V, VII, VIII, IX, X, XI, XII, and XIII, Protein C, and Protein S are synthesized in the Hver. Factor III is present in many different organs throughout the body. Factor IV is the divalent cation calcium. The concentration of calcium required for normal function of the blood coagulation system is much less than required for normal physiologic function of many organs in the body, eg, myocardium. 

Coagulation Factor VIII-SD VIII C Vactor T7/I SD New York Blood Center... 

Activated Proteia C (C ) [42617-41 -4] (19—21) is a aaturaHy occurring serine protease that, ia combination with free Proteia S, degrades and iaactivates Factors V, Va, VIII, and Villa. By degradation of these factors the blood becomes anticoagulated and thus may be a useful therapeutic agent. 

Title VIII Supervision and sanctions Tide X Special provisions on medicinal products derived from human blood and plasma Tide XI Supervision and sanctions... 

Von Willebrand factor (VWF) is a large multimeric glycoprotein with two main functions in hemostasis to aid the platelet adhesion to injured blood vessel walls and to carry and stabilize factor VIII in plasma. Table 64—4 represents three main vWD phenotypes, their frequency, and genetic transmission.17... 

Activated partial thromboplastin time aPTT is performed by adding calcium phospholipids and kaolin to citrated blood and measures the time required for a fibrin clot to form. In this manner, aPTT measures the activity of intrinsic and common pathways. Prolongation of aPTT may be due to a deficiency or inhibitor for factors II, V, VIII, IX, X, XI, and XII. It also may be due to heparin, direct thrombin inhibitors, vitamin K deficiency, liver disease, or lupus anticoagulant. 

Cryoprecipitate Component of blood obtained by freezing and thawing plasma that is rich in clotting factors. One unit of cryoprecipitate derived from a unit of whole blood contains a volume of 10 to 20 mL, 80 to 100 units of factor VIII which consists of both the procoagulant activity and the von Willebrand factor, 150 to 250 mg of fibrinogen, 50 to 100 units of factor XIII, and 50 to 60 mg of fibronectin. 

Accelerates the actions of several blood clotting factors (VIII, IX, X, XI, and XII)... 

Using the same logic, the PTO has granted patents, for example, for pure cultures of specific microorganisms and for medically important proteins (e.g. Factor VIII purified from blood (Chapter 12) and EPO purified from urine (Chapter 10)). 

Many small proteins, in particular those that function extracellularly (e.g. insulin, GH and various cytokines) are quite stable and may be fractionated on a variety of HPLC columns without significant denaturation or decrease in bioactivity. Preparative HPLC is used in industrial-scale purification of insulin and of IL2. In contrast, many larger proteins (e.g. blood factor VIII) are relatively labile, and loss of activity due to protein denaturation may be observed upon high-pressure fractionation. 

Intact factor VIII, as usually purified from the blood, consists of two distinct gene products factor VIII and (multiple copies of) von Willebrand s factor (vWF Figure 12.6). This complex displays a molecular mass ranging from 1 to 2 MDa, of which up to 15 per cent is carbohydrate. The fully intact factor VIII complex is required to enhance the rate of activation of factor IX of the intrinsic system. 

Persons suffering from haemophilia A exhibit markedly reduced levels (or the complete absence) of factor VIII complex in their blood. This is due to the lack of production of factor VIII C. 

Persons expressing 5 per cent or above of the normal complex levels experience less severe clinical symptoms. Treatment normally entails administration of factor VIII complex purified from donated blood. More recently, recombinant forms of the product have also become available. Therapeutic regimens can require product administration on a weekly basis, for life. About 1 in 10 000 males are born with a defect in the factor VIII complex and there are approximately 25 000 haemophiliacs currently resident in the USA. 

Native factor VIII is traditionally purified from blood donations first screened for evidence of the presence of viruses such as hepatitis B and HIV. A variety of fractionation procedures (initially mainly precipitation procedures) have been used to produce a factor VIII product. The final product is filter-sterilized and filled into its finished product containers. The product is then freeze-dried and the containers are subsequently sealed under vacuum, or are flushed with an inert gas (e.g. N2) before sealing. No preservative is added. The freeze-dried product is then stored below 8 °C until shortly before its use. 

Production of recombinant factor VIII (Table 12.2) has ended dependence on blood as the only source of this product, and eliminated the possibility of transmitting blood-borne diseases specifically derived from infected blood. In the past, over 60 per cent of haemophiliacs were likely to be accidentally infected via contaminated products at some stage of their life. 

Several companies have expressed the cDNA coding for human factor VIII C in a variety of eukaryotic production systems (human VIII C contains 25 potential glycosylation sites). CHO cells and BHK cell lines have been most commonly used, in addition to other cell lines, such as various mouse carcinoma cell lines. The recombinant factor VIII product generally contains only VIII C (i.e. is devoid of vWF). However, both clinical and preclinical studies have shown that administration of this product to patients suffering from haemophilia A is equally as effective as administering blood-derived factor VIII complex. The recombinant VIII C product appears to bind plasma... 

Exchange transfusion of whole blood. This will transiently decrease circulating anti-factor VIII C antibodies. 

Owing to the frequency of product administration, the purification procedure for recombinant factor VIII C must be particularly stringent. Unlike the situation pertaining when the product is purified from human blood, any contaminant present in the final product will be non-human and, hence, immunogenic. Sources of such contaminants would include ... 

Individuals who display a deficiency of factor IX develop haemophilia B, also known as Christmas disease. Although its clinical consequences are very similar to that of a deficiency of factor VIII, its general incidence in the population is far lower. Persons suffering from haemophilia B are treated by i.v. administration of a concentrate of factor IX. This was traditionally obtained by fractionation of human blood. Recombinant factor IX is now also produced in genetically engineered CHO cells (Table 12.2 and Box 12.1). 

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