Search

Your search keyword '"Lawrie, Andrew S."' showing total 21 results
Start Over Author "Lawrie, Andrew S."
21 results on '"Lawrie, Andrew S."'

12. Procoagulant activity in patients with sickle cell trait

Author

Lawrie, Andrew S., Pizzey, Arnold, Trompeter, Sara, Meiselman, Herbert, Mohandas, Narla, Dumanski, Jan P., Westerman, Maxwell P., Lawrie, Andrew S., Pizzey, Arnold, Trompeter, Sara, Meiselman, Herbert, Mohandas, Narla, Dumanski, Jan P., and Westerman, Maxwell P.

Abstract

Patients with sickle cell trait (STr) are usually considered to be asymptomatic. However, complications, including hypercoagulability, increased risk of venous thromboembolism and the exertional exercise syndrome with rhabdomyolysis and sudden death, have been described. The exact cause of these adverse events is unclear. We have investigated two patients, a set of monozygotic twins with STr, to establish their procoagulant activity status as a potential indicator of thrombotic risk. In-vivo thrombin generation was assessed by the measurement of prothrombin fragment 1+2 (F1+2) and thrombin-antithrombin complexes (TAT). D-dimer was used as a marker of fibrinolytic activity. The potential to generate thrombin was determined using an ex-vivo thrombin generation test (TGT). The impact of red blood cell (RBC)-derived microparticle shedding and RBC rheology were examined. TAT (>60 mu g/l) and F1+2 (948 pmol/l) were markedly elevated in patient 2 but within the normal reference range in patient 1 (TAT=2.5 mu g/l; F1+2=138 pmol/l). D-dimer levels (0.9 mg/l FEU) were similarly elevated in both patients. TGT peak thrombin and endogenous thrombin potential (ETP) were elevated to similar degrees in both patients. Flow cytometric analysis for RBC-derived microparticles showed that both patients had elevated levels on two occasions. RBC deformability, blood viscosity and RBC aggregation were normal and similar in both patients. The results demonstrated different coagulation activity in the patients with one patient in a prothrombotic state, suggesting that there may be two levels of hypercoagulability in STr. Measurement of such differences would allow for separation of high and low-risk patients from serious complications.

Published
2012
Full Text
View/download PDF

20. A multicentre assessment of the endogenous thrombin potential using a continuous monitoring amidolytic technique.

Author

Lawrie, Andrew S., Gray, Elaine, Leeming, Dave, Davidson, Simon J., Purdy, Gordon, Iampietro, Romina, Craig, Steve, Rigsby, Peter, and Mackie, Ian J.

Subjects
*THROMBIN, *LABORATORY techniques
Abstract

This study assessed the inter-laboratory imprecision associated with the measurement of the endogenous thrombin potential (ETP). The initial studies used techniques that had evolved in each of the participating laboratories. Samples from normal healthy subjects ( n = 10), two patients receiving coumarin therapy [International Normalized Ratio ∼2·0 and ∼4·0] and a further two subjects receiving treatment with unfractionated heparin (anti-Xa 0·07 iu/ml and 0·31 iu/ml) were assayed relative to a lyophilized normal plasma that had arbitrarily been assigned a potency of 100%. Considerable variation in potency estimates was observed between the centres, although individual laboratories using fully automated techniques achieved acceptable levels of imprecision as assessed by the coefficient of variation (CV) (intra-assay CV < 9·5%, inter-assay CV < 12·5%). A second study to assess a similar range of samples, using a standardized assay protocol and incorporating appraisal of two chromogenic substrates, CBS.0068 or Pefachrom® TG, demonstrated markedly improved agreement in potency estimates between centres and good correlation ( r > 0·96) between the chromogenic substrates. Our data demonstrates that an automated ETP method can be standardized between laboratories and suitable levels of imprecision achieved, using different analysers (COBAS Mira at two centres and an ACL-300R) and two thrombin substrates. This indicates that more widespread use of ETP measurements in clinical laboratories is feasible. [ABSTRACT FROM AUTHOR]

Published
2003
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results