The aim of the study was to determine the effect of the antithrombin concentration on the anticoagulant response to heparin in vitro. Pooled plasma was depleted of antithrombin using heparin Sepharose. Unfractionated heparin (final concentration between 0 and 1 U/ml) was added to plasma with different antithrombin concentrations, and the activated partial thromboplastin time (APTT) was determined. Plasma with an antithrombin concentration over 0.27 U/ml shows a similar response to heparin as normal plasma; at lower levels the response is diminished. Even in plasma fully depleted of antithrombin, the APTT can be prolonged to a therapeutic level, although the amount of heparin needed is twice as high. At antithrombin concentrations over 0.27 U/ml, heparin is the major determinant of the anticoagulant effect.
SummaryAccelerated degradation experiments were performed to assess the heat stability of lyophilized recombinant tissue factor-liposome preparations from two different manufacturers. When stored at 4° C, these preparations did not show a significant change of the prothrombin time (PT). Two preparations (coded rTF-2 and rTF-a) showed a progressive prolongation of the PT on storage at 30° C, 37° C, and 44° C. The third preparation showed an initial decrease of the PT at 37° C and 44° C followed by a progressive prolongation. Although none of the three preparations was absolutely stable at 30° C, 37° C and 44° C, rTF-2 had the advantage that its PT-ratio (and hence its International Sensitivity Index) did not change under the conditions used in this study. The PT-ratio with a reference material for rabbit brain tissue factor (CRM149S) stored under similar conditions, did not change either.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.