Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.2.2.7 (heparinase)
 1,270 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of this study was to determine the prevalence and effect of heparin contamination in samples drawn from implanted venous access devices (VADs, ports) on factor VIII activity and Bethesda inhibitor assay (BU) and the efficacy of heparinase to neutralize heparin. Plasma samples containing 85, 45, and 2 U/dL factor VIII were spiked in vitro with heparin from 0 to 3 U/mL. Factor VIII activity was assayed with a one-stage clotting assay on paired samples before and after heparinase, 25 mg/mL plasma. Paired patient samples drawn from VADs were assayed for heparin concentration, factor VIII, and BU before and after heparinase. At all three concentrations of factor VIII in vitro, the addition of heparin at 0.12 to 0.25 U/mL decreased assayed factor VIII activity. Heparinase neutralized up to 2 U/mL heparin and resulted in accurate factor VIII determination. Of 105 VAD samples, 47 (45%) had heparin contamination >0.05 U/mL. Of 47 heparin-contaminated samples, 42 showed decreased factor VIII activity in before/after comparisons. False-positive BU results were detected in 6 of 47 heparin-contaminated samples. Heparin contamination occurs frequently in samples drawn from VADs and could increase costs through excessive factor concentrate use. We recommend that all VAD samples be pretreated with heparinase before the assay of factor VIII activity or Bethesda inhibitor titers.
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PMID:Heparin neutralization is essential for accurate measurement of factor VIII activity and inhibitor assays in blood samples drawn from implanted venous access devices. 1088 30

: Coronary artery bypass grafting surgery (CABG) in hemophilia patients is challenging. Thromboelastography (TEG) is useful to assess hemostasis perioperatively. A patient with severe hemophilia A underwent CABG with TEG studies. After factor VIII (FVIII) bolus dose, TEG was normalized. Following 'on-pump' heparinization, protamine administration revealed prolonged TEG-R and TEG-R with heparinase confirming it, whereas the activated clotting time was normal, suggesting low FVIII activity rather than excess of heparin. Another FVIII bolus yielded complete normalization of all TEG parameters. Data are compatible with in-vitro assays performed in our laboratory, showing that both heparin and protamine may impair measurable FVIII activity. The rational use of TEG measurements enabled more accurate hemostatic therapy application with regard to FVIII, heparin and protamine administration. Adopting this approach may lead to a better therapy tailoring for hemophilia patients undergoing CABG surgery.
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PMID:Thromboelastography during coronary artery bypass grafting surgery of severe hemophilia A patient - the effect of heparin and protamine on factor VIII activity. 2727 41