News & Upcoming Events

Microparticle Activity Analysis

Microparticles are small vesicles that are released from cells (such as platelets and endothelial cells) and can be found circulating in the blood. The microparticle consists of a plasma membrane which surrounds a small amount of cytosol. The membrane of the microparticle contains receptors and other cell surface molecules.  The activity of microparticles in thrombin generation is dependent upon the expression of anionic phospholipids such as phosphatidylserine.  Circulating microparticles can be found in the blood of normal individuals. Phosphatidylserine is a known cofactor in prothrombin activation and increased numbers of circulating microparticles have been identified in individuals with certain diseases, including hypertension, prothrombotic states such as thrombotic thrombocytopenic purpura and the antiphospholipid antibody syndrome.

Genotyping for Warfarin Therapy

Cytochrome P450 2C9 gene (CYP2C9) & Vitamin K Epoxide Reductase Complex 1 gene (VKORC1) genotyping is now available.  CYP2C9 is an important enzyme in the metabolism of warfarin.  It affects the half life and time to a stable dose.  Without genetic testing, it is not known if an INR test result represents a steady state or one that is climbing.  VKORC1 is the site of action of warfarin and when more receptor is present, more warfarin is required.  Variants in the CYP2C9 and VKORC1 genes have been shown to significantly influence warfarin dose requirements and in the case of CYP2C9, the risk of major bleeds.  An FDA advisory panel has indicated: "Genotyping patients in the induction phase of warfarin therapy would reduce adverse events and improve achievement of stable INR and existing evidence of the influence of CYP2C9 and VKORC1 genotypes warrants re-labeling of warfarin to include genetic test information."  The FDA and others are sponsoring clinical trials to prove the extent to which using DNA testing will reduce the morbidity and mortality associated with warfarin induced adverse bleeding events.  Many scientists believe that the use of this testing will dramatically improve warfarin efficacy and safety.

Molecular Cancer Therapeutics Article

Lucy Shin, the recipient of the HRL Scholarship for 2006, has had an article published, titled "Effects of the chemotherapeutic agent doxorubicon on the protein C anticoagulent pathway" which can be found in Molecular Cancer Therapeutics 2006;5(12) December 2006 pages 3303-3311.  Lucy continues to investigate the Protein C pathway with Dr. Patricia Liaw's group.  HRL has provided testing for several of Dr. Liaw's Sepsis Studies.

New International Standards for Medical Laboratory Quality

ISO 15189, the quality systems standard for management of medical laboratories has now passed through the ISO approval process. The International Standard became available for public release on February 10, 2003.   For further information, please visit ISO 15189:2003.

Xa Heparin assays for establishing an aPTT therapeutic range for Unfractionated Heparin (UFH)

 How it works: 

1. The laboratory requiring development of an aPTT therapeutic range for UFH heparin therapy undertakes to collect a minimum of 30 patients on intravenous heparin.  The patients must not have received Coumadin for more than 24 hours before blood taking or not be taking coumadin.

2. Within 1 hour of collection, blood samples are centrifuged at a minimum of 1700G for 15 minutes, the plasma removed to a clean tube, re-centrifuged for 5 minutes at 1700G or more and split into 2 microtube aliquots.  The plasma is then frozen at -35C or lower until testing is performed.

3. After collecting a minimum of 30 patient samples, one of the two microtube aliquots of platelet-free citrated plasma is shipped frozen on dry ice to HRL. 

4. The laboratory can then measure the aPTT with the second aliquot of frozen plasma using their aPTT reagent and routine instrumentation.  It is important to assure the systems have acceptable quality control runs before the heparin plasmas are tested.  The plasma should be thawed at 37°C for 5 minutes and the APTT measured.

5. The results of the Xa heparin assay are returned to the laboratory and using the supplied Microsoft Excel spreadsheet, the laboratory enters the aPTT values to perform a linear regression analysis.  The spreadsheet has an analysis program containing the algebraic equation for linear regression.  A heparin level of 0.35 to 0.7 U/mL is considered the therapeutic range.  A line can be drawn to intersect the regression line for the determination of aPTT values in seconds representing the equivalent heparin values. 

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