Biomaterial Database

Discordance between the anti-Xa activity and the antithrombotic activity in an ultra-low molecular weight heparin fraction. 1982

P A Ockelford, and C J Carter, and L Mitchell, and J Hirsh

The relationship between the in vivo antithrombotic effect of heparin and ex vivo anti-Xa activity has been investigated using an animal thrombosis model. Three low molecular weight heparins were compared with the standard heparin from which they were fractionated. All four heparins showed a dose-dependent antithrombotic effect enabling the relative antithrombotic and anti-Xa activities to be compared over a dosage range. A correlation between ex vivo anti-Xa heparin levels and antithrombotic effect was demonstrated for the standard (MW 16,000), intermediate (MW 7,600) and low (MW 4,600) molecular weight heparins but not for the ultra-low molecular weight (MW 3,000) fraction. The lack of relationship between anti-Xa activity and inhibition of thrombosis for the very low molecular weight fraction indicates that a very high anti-Xa activity (measured in vitro or ex vivo) is not always predictive of in vivo antithrombotic efficacy. These findings suggest that other properties of low molecular weight heparins contribute to their antithrombotic effectiveness.

UI	MeSH Term	Description	Entries
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D010314	Partial Thromboplastin Time	The time required for the appearance of FIBRIN strands following the mixing of PLASMA with phospholipid platelet substitute (e.g., crude cephalins, soybean phosphatides). It is a test of the intrinsic pathway (factors VIII, IX, XI, and XII) and the common pathway (fibrinogen, prothrombin, factors V and X) of BLOOD COAGULATION. It is used as a screening test and to monitor HEPARIN therapy.	Activated Partial Thromboplastin Time,Cephalin-Kaolin Coagulation Time,Kaolin-Cephalin Coagulation Time,Thromboplastin Time, Partial,Coagulation Time, Cephalin-Kaolin,Cephalin Kaolin Coagulation Time,Coagulation Time, Cephalin Kaolin,Coagulation Time, Kaolin-Cephalin,Kaolin Cephalin Coagulation Time
D011517	Prothrombin Time	Clotting time of PLASMA recalcified in the presence of excess TISSUE THROMBOPLASTIN. Factors measured are FIBRINOGEN; PROTHROMBIN; FACTOR V; FACTOR VII; and FACTOR X. It is used for monitoring anticoagulant therapy with COUMARINS.	Quick Test,Russell's Viper Venom Time,Thrombotest,Russell Viper Venom Time,Russells Viper Venom Time,Prothrombin Times,Test, Quick,Time, Prothrombin,Times, Prothrombin
D011817	Rabbits	A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes.	Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D005170	Factor X	Storage-stable glycoprotein blood coagulation factor that can be activated to factor Xa by both the intrinsic and extrinsic pathways. A deficiency of factor X, sometimes called Stuart-Prower factor deficiency, may lead to a systemic coagulation disorder.	Autoprothrombin III,Coagulation Factor X,Stuart Factor,Stuart-Prower Factor,Blood Coagulation Factor X,Factor 10,Factor Ten,Stuart Prower Factor,Factor X, Coagulation
D005340	Fibrinogen	Plasma glycoprotein clotted by thrombin, composed of a dimer of three non-identical pairs of polypeptide chains (alpha, beta, gamma) held together by disulfide bonds. Fibrinogen clotting is a sol-gel change involving complex molecular arrangements: whereas fibrinogen is cleaved by thrombin to form polypeptides A and B, the proteolytic action of other enzymes yields different fibrinogen degradation products.	Coagulation Factor I,Factor I,Blood Coagulation Factor I,gamma-Fibrinogen,Factor I, Coagulation,gamma Fibrinogen
D006493	Heparin	A highly acidic mucopolysaccharide formed of equal parts of sulfated D-glucosamine and D-glucuronic acid with sulfaminic bridges. The molecular weight ranges from six to twenty thousand. Heparin occurs in and is obtained from liver, lung, mast cells, etc., of vertebrates. Its function is unknown, but it is used to prevent blood clotting in vivo and vitro, in the form of many different salts.	Heparinic Acid,alpha-Heparin,Heparin Sodium,Liquaemin,Sodium Heparin,Unfractionated Heparin,Heparin, Sodium,Heparin, Unfractionated,alpha Heparin
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000991	Antithrombins	Endogenous factors and drugs that directly inhibit the action of THROMBIN, usually by blocking its enzymatic activity. They are distinguished from INDIRECT THROMBIN INHIBITORS, such as HEPARIN, which act by enhancing the inhibitory effects of antithrombins.	Antithrombin,Direct Antithrombin,Direct Antithrombins,Direct Thrombin Inhibitor,Direct Thrombin Inhibitors,Antithrombin, Direct,Antithrombins, Direct,Inhibitor, Direct Thrombin,Thrombin Inhibitor, Direct,Thrombin Inhibitors, Direct

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