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Composition, kit and method for assaying heparin and a method for making the composition

  • US 4,946,775 A
  • Filed: 06/09/1989
  • Issued: 08/07/1990
  • Est. Priority Date: 09/05/1985
  • Status: Expired due to Fees
First Claim
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1. A method for determining the concentration of heparin in a blood plasma sample which comprises(A) incubating the blood plasma sample for a limited period of time with a known amount of Factor Xa, to form an incubated product which known amount is in excess of the amount needed to react with all heparin - AT III complexes in the blood plasma sample within a given time period,(B) combining the incubated product of step (A) with an admixture of(1) calcium chloride,(2) brain phospholipids, and(3) a buffered plasma fraction that has been produced by treating mammalian blood to substantially remove clotting Factors II, VII, IX and X while retaining clotting Factor V and fibrinogen,said admixture being characterized by the fact that(a) it does not clot by itself for at least 24 hours at 37°

  • C., and(b) it forms a firm clot in the presence of added thrombin, and(c) it contains at least 50% of Factor V that is present in one ml of normal human plasma, and(d) it provides a linear heparin dilution curve using a standard heparin preparation, and(C) measuring the time it takes for clotting to occur after combining the incubated product of step (A) with said admixture, which clotting time is directly proportional to the concentration of heparin present in the blood plasma sample.

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