Factor X, deficiency

Dewerchin M, Liang Z, Moons L et al. (2000) Blood coagulation factor X deficiency causes partial embryonic lethality and fatal neonatal bleeding in mice. Thromb Haemost 83 185-190... 

Connolly AJ, Ishihara H, Kahn ML et al. (1996) Role of the thrombin receptor in development and evidence for a second receptor. Nature 381 516-519 Cui J, O Shea KS, Purkayastha A et al. (1996) Fatal haemorrhage and incomplete block to embryogenesis in mice lacking coagulation factor V. Nature 384 66-68 Denis C, Methia N, Frenette PS et al. (1998) A mouse model of severe von Willebrand disease defects in hemostasis and thrombosis. Proc Nad Acad Sci USA 95 9524-9529 Dewerchin M, Liang Z, Moons L et al. (2000) Blood coagulation factor X deficiency causes partial embryonic lethality and fatal neonatal bleeding in mice. Thromb Haemost 83 185-190... 

Carter C, Winfield DA. Factor X deficiency during treatment of relapsed acute myeloid leukaemia with amsacrine. Clin Lab Haematol 1988 10(2) 225-8. 

Stuart-Prower factor (Autoprothrombin III) X Factor X deficiency Very rare 8 0.15 Liver 24-50 lAPO, ICCF, IFAX, IHCG, IKIG, IWHE, IWHF FA10 HUMAN... 

Specific factor assays are variations on the APTT or PT tests. In the APTT and PT, dilutions of the patient s plasma are made into a deficient, or depleted, substrate plasma. The assays are then performed in the usual way. The clotting times are compared with those obtained from dilutions of pooled normal plasma, commonly 1 10, 1 20, 1 50, and 1 100. A graph of the logarithm of the clotting time (y axis) versus the logarithm of the concentration as percentage of normal x axis) is used to determine the amount of the factor activity in the patient s plasma. The normal pooled plasma is conventionally assigned a value of 100% activity. Many variations exist for specific factor assays, e.g., the venom of Vipera russellii and phospholipids may be substituted for thromboplastin in a PT-like assay. An enzyme in Russell s viper venom rapidly and relatively specifically activates factor X. In conjunction with a factor X-deficient substrate plasma, this provides a specific factor X assay. 

Heparin therapy may be monitored by its increases in clotting time in the APTT, although this method for measuring heparin is difficult to standardize. Heparin is more specifically assayed by its effect on factor Xa inactivation by antithrombin. Such factor Xa-based heparin assays usually employ purified factor Xa as a reagent and factor X-deficient substrate plasma as the source of antithrombin. The prolongation of the clotting time that results from the heparin in the patient s plasma is compared with pooled normal plasma that is known to be free of heparin. Many variations of this heparin assay are available. Heparin assays can use thrombin rather than factor Xa, however, the low-molecular-weight heparins are not reliably measured in thrombin-based assays. 

Congenital deficiency of Factor X is a rare autosomal recessive disorder. Several variants have been described. 

Several substances that contribute to the blood coagulation process are formed in the liver. These include fibrinogen, prothrombin, and several of the blood clotting factors (II, VII, IX, and X). Deficiency in any of these substances leads to impaired blood coagulation. 

In normal individuals phytonadione and the menaquinones have no activity while in vitamin K deficiency the vitamin promotes the hepatic biosynthesis of factor II (prothrombin), factor VII, factor IX and factor X. Vitamin K functions as an essential cofactor for the enzymatic activation of precursors of these vitamin K dependent clotting factors. The quinone structure of the active form of vitamin K, i.e. reduced vitamin K or hydroquinone. 

Clinical pharmacology Activated factor IX in combination with activated factor VIII activates factor X. This results ultimately in the conversion of prothrombin to thrombin. Thrombin then converts fibrinogen to fibrin, and a clot can be formed. Factor IX is the specific clotting factor deficient in patients with hemophilia B and in patients with acquired factor IX deficiencies. The administration of Coagulation Factor IX (Recombinant) increases plasma levels of factor IX and can temporarily correct the coagulation defect in these patients. 

PrekaUikrein is converted to kaUrkrem and factor XII is activated to Xlla. Factor Xlla activates Xl-XIa, which activates factor IX, which together with its co-factor Villa forms the tenase complex, resniting in activation of factor X. The minor role that the contact activation pathway has in initiating clot formation can he Ulnstrated hy the fact that patients with severe deficiencies of factor Xn, kininogen and prekaUikrein do not exhibit a bleeding disorder. 

Prolongation of the prothrombin time after the use of amsacrine 1200 mg/m for acute myeloid leukemia was related to transient deficiency of factor X (67). 

The answer is e. (Murray, pp 812-828. Scriver, pp 3-45. Sack, pp 121—144. Wilson, pp 23—98.) Hemophilia A is caused by deficiency of factor VIII and hemophilia B by deficiency of factor IX. Both factors are involved in the intrinsic blood coagulation pathway that results in activation of factor X. Alternatively, factor X can be activated by tissue factors through the extrinsic blood coagulation pathway Activated factors X and V produce thromin from prothrombin, which in turn cleaves fibrinogen to produce fi-... 

Duffy, E.J., Lollar, P. 1992. Intrinsic pathway activation of factor X and its activation pep-tide-deficient derivative, factor Xdes-143-191,... 

Phytonadione is a blood modifier/vitamin K. It promotes hepatic synthesis of active prothrombin (factor II), proconvertin (factor VII), plasma thromboplastin component (factor IX) and Stuart factor (factor X). It is indicated in the management of coagulation disorders due to faulty formation of factors II, Vn, IX, and X due to vitamin K deficiency or interference with vitamin K activity. Oral/parenteral used for treatment of anticoagulant-induced prothrombin deficiency treatment of hypoprothrombinemia secondary to salicylates or antibacterial therapy, or secondary to obstructive jaundice and biliary fistulas, provided bile salts are also given. Parenteral used for treatment of hypoprothrombinemia secondary to conditions limiting absorption or synthesis of vitamin K prophylaxis and therapy of hemorrhagic disease of the newborn. 

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