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Biomedical subjects

B Woodhams

Publications and source records attributed to B Woodhams.

9 recordsLinked to original sources

Diagnosis and prognosis of overt disseminated intravascular coagulation in a general hospital -- meaning of the ISTH score system, fibrin monomers, and lipoprotein-C-reactive protein complex formation.

The meaning, the utility, and the prognostic significance of the International Society of Thrombosis and Hemostasis overt disseminated intravascular coagulation (DIC) score and other parameters of coagulation activation including soluble fibrin monomer complexes (SFMC), antithrombin and protein C consumption, and formation of lipoprotein-C-reactive protein (LP-CRP) complexes (MDA slope 1 and flag A2) were evaluated in 165 inpatients from a general hospital for whom DIC testing was required by the attending physicians. Of these 165 patients, 148 had an underlying disease that clearly justified the laboratory request from our systematic post hoc review of the clinical charts. Of these 148 patients, 28 had a positive overt DIC score, 19 had an A2 flag, and 4 had both. The DIC score was strongly related to several major markers of coagulation activation such as D-dimers, thrombin-antithrombin complexes, and soluble fibrin and was inversely related to antithrombin and protein C levels, which began to fall from DIC score 4 or higher. The formation of LP-CRP complexes was only related to Gram-negative sepsis and these patients had a strong inflammatory reaction. Independent risk factors for death were high creatininemia, positive overt DIC score, and/or presence of SFMC. In patients with positive DIC score, SFMC positivity and low levels of antithrombin and/or protein C were additional risk factors. The ISTH overt DIC score proves useful and adequate as a marker for clinically significant DIC. Illness severity is further defined by SFMC, antithrombin, and protein C levels. LP-CRP complexes are related to sepsis but not to actual overt DIC and lethal prognosis.

Biomarkers↗

Stability of coagulation proteins in frozen plasma.

This study reports on the frozen stability of all commonly measured coagulation proteins in normal citrated plasma: activated partial thromboplastin time, prothrombin time (%), thrombin time and fibrinogen (Clauss); clotting assays for factors II, V, VII, VIII, IX, X, XI and XII; functional assays for protein C (clotting), protein S (clotting), antithrombin (chromogenic) and plasminogen (chromogenic); and immunological assays for von Willebrand factor and D-dimer. All these factors listed are stable for up to 3 months if frozen at -24 degrees C or lower. At -74 degrees C, all these factors (allowing for 10% variation) were stable for at least 18 months, most were stable for 24 months. The number of proteins showing > 5% variation over baseline after 6 months storage indicates that some decay does occur even at -74 degrees C. There was no clear advantage in snap freezing at -74 degrees C and then storing at -24 degrees C over both freezing and storing at -24 degrees C; therefore, the freezing process itself is not responsible for the loss of stability. The best stability, especially at -24 degrees C, was obtained when small samples (1 ml) were stored in screw-cap tubes with a minimum dead space. The decrease in stability of the coagulation proteins directly correlates with the effect of temperature and time.

Blood Coagulation↗

The ISI/INR system.

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Blood Chemical Analysis↗

Effects of chemical modifiers on recombinant factor VIII activity.

Factor VIII performs a critical role in the blood coagulation cascade but is extremely labile. We have carried out chemical studies on a fully functional recombinant Factor VIII (rFVIII) using a variety of protein modifying agents, some of which were bifunctional. Thiol-specific maleimides cause no activity loss despite a substantial decrease in rFVIII's free thiol content. Mild oxidation procedures had either neutral or adverse effects on activity. Amino-specific reagents led to significant losses of rFVIII procoagulant activity. It appears that free amino groups are essential for Factor VIII's function while some at least of its many free thiol groups are not. None of these derivatives was any less labile than unmodified rFVIII. Systematic chemical modification of important proteins in this way can give useful insights into appropriate protein engineering strategies.

Amines↗

[Initial experiences with a recombinant human tissue thromboplastin in oral anticoagulation].

A recombinant tissue factor (rTF, Batch TFS-RD3, Baxter Diagnostics) has been assessed by plasma and capillary blood methods and compared with our working rabbit brain thromboplastin (CRB Roche, Basel, Switzerland) for its suitability in monitoring oral anticoagulant therapy. The international sensitivity index (ISI) for rTF calibrated against CRB has been found to be 0.73 and 0.69 respectively. The slope of the orthogonal regression line between log prothrombin time rTF plasma and rTF capillary blood is 0.96. Thus, we considered the ISI to be identical for both methods. International normalized ratios calculated with these assumptions, and even activity percentages assigned by a dilution curve, did not differ from the results obtained with our working thromboplastin. The human recombinant thromboplastin TFS-RD3 seems to have properties similar to currently used commercial thromboplastins. Recombinant tissue factor as a well defined preparation could make essential contributions to the standardization of prothrombin time and to the improvement of oral anticoagulant therapy.

Animals↗

The specificity of antisera raised by oestradiol-17beta-3-hemisuccinyl-bovine serum albumin.

The preparation of pure oestradiol-17beta-3-hemisuccinyl-bovine serum albumin conjugate is described. Contrary to previous findings this antigen raised reasonably specific antisera in rabbits which possessed a cross reaction of only 2.0% with oestrone, and 0.8% with oestriol. The production of this specific antisera is considered to be due to the high purity of the antigen. The role of the C-3 phenolic hemisuccinyl linkage of the antigen in raising this specific antisera is discussed.

Antibody Specificity↗