Measuring the Quality of Personal Care in Patients Undergoing Radiotherapy for Prostate Cancer.

AIMS: To describe the quality of the non-technical component of the care (personal care) of patients receiving radical radiotherapy for prostate cancer and to identify elements of personal care that should be priorities for quality improvement. MATERIALS AND METHODS: One hundred and eight patients undergoing radiotherapy for localised prostate cancer completed a self-administered questionnaire that asked them to rate the importance of 143 non-technical elements of care and to rate the quality of their own care with respect to each element. The elements that a patient rated as both 'very important' and less than 'very good' were deemed to be his priorities for improvement. The priorities of the population were established by ranking the elements based on the percentage of patients who identified them as a priority (importance/quality analysis). RESULTS: The response rate was 65%. The percentage of elements rated 'very good' varied from patient to patient: median 79% (interquartile range 69-92%). The percentage of elements rated either 'very good' or 'good' was higher: median 96% (interquartile range 86-98%). Nonetheless, almost every patient rated at least some elements of his care as less than optimal, regardless of the cut-off point used to define optimal quality. Patients assigned their lowest quality ratings to elements relating to the quality of the treatment environment and comprehensiveness of additional services available to them. However, patients rated most of these elements as relatively unimportant, and importance/quality analysis identified elements of care relating to communication of information about the disease and its treatment as the highest priorities for quality improvement. CONCLUSIONS: Most patients rated most elements of their personal care as very good, but almost all were able to identify some elements that were less than optimal. When ratings of quality were integrated with ratings of importance, elements relating to communication emerged as the patients' highest priorities for quality improvement.

Interplay between fibrinolysis and complement: plasmin cleavage of iC3b modulates immune responses.

BACKGROUND: The plasmin(ogen) and complement systems are simultaneously activated at sites of tissue injury, participating in hemostasis, wound healing, inflammation and immune surveillance. In particular, the C3 proteolytic fragment, iC3b, and its degradation product C3dg, which is generated by cleavage by factor I (FI) and the cofactor complement receptor CR1, are important in bridging innate and adaptive immunity. Via a thioester (TE) bond, iC3b and C3dg covalently tag pathogens, modulating phagocytosis and adaptive immune responses. OBJECTIVE: To examine plasmin-mediated proteolysis of iC3b, and to evaluate the functional consequences, comparing the effects with products generated by FI/CR1 cleavage of iC3b. METHODS: Dose-dependent and time-dependent plasmin-mediated cleavage of iC3b were characterized by analytical gel electrophoresis. The properties of the resultant TE bond-containing fragments on phagocytosis and induction of pro-inflammatory cytokines were measured in cell culture systems. RESULTS: At low concentrations, plasmin effectively cleaves iC3b, but at numerous previously undescribed sites, giving rise to novel C3c-like and C3dg-like moieties, the latter of which retain the TE bond. When attached to zymosan or erythrocytes and exposed to THP-1 macrophages, the C3dg-like proteins behave almost identically to the bona fide C3dg, yielding less phagocytosis as compared with the opsonin iC3b, and more macrophage secretion of the pro-inflammatory cytokine, IL-12. CONCLUSION: Plasmin cleavage of iC3b provides a complement regulatory pathway that is as efficient as FI/CR1 but does not require a cellular cofactor.

FXIII: mechanisms of action in the treatment of hemophilia A.

BACKGROUND: Hemophilia is characterized by abnormal thrombin generation and impaired clot stability. FXIII promotes clot stability and may be a useful adjunct treatment for hemophilia. OBJECTIVES: This study examined the clot stabilizing effects and safety of supra-physiological FXIII and explored the mechanisms via which FXIII exerts its effects in hemophilia A. METHODS: The effects of FXIII on clot formation and stability were examined using a thromboelastometry assay and blood samples collected from six patients with severe hemophilia A. The effect of FXIII on clot formation was also assessed using a murine model. The mechanisms of FXIII action in hemophilia A were explored by measuring thrombin generation, rates of FXIII activation and effects on clot permeability, pore size and fibrin fiber diameter. RESULTS: This study demonstrates that supra-physiological concentrations of FXIII stabilize clots in blood from patients with hemophilia by improving resistance to t-Pa-induced fibrinolysis even at low concentrations of FVIII (FVIII< 0.1 IU mL⁻¹, P < 0.05, anova). Addition of FXIII stoichiometrically up-regulates its activation, correcting the fibrin clot structure, reducing clot permeability and facilitating thrombin generation; FXIII significantly shortens ttPeak and lagtime (P < 0.05) in FVIII-deficient plasma, providing a novel explanation for its positive effects on clot stability and structure. The murine model indicates that supra-physiological FXIII is tolerated and does not significantly alter time to clot formation. CONCLUSION: The effects of FXIII on clot stability and physical clot structure are seen at low concentrations of FVIII, indicating that FXIII could be a useful treatment in a variety of clinical scenarios.

Insights into thrombin activatable fibrinolysis inhibitor function and regulation.

Fibrinolysis is initiated when the zymogen plasminogen is converted to plasmin via the action of plasminogen activators. Proteolytic cleavage of fibrin by plasmin generates C-terminal lysine residues capable of binding both plasminogen and the plasminogen activator, thereby stimulating plasminogen activator-mediated plasminogen activation and propagating fibrinolysis. This positive feedback mechanism is regulated by activated thrombin activatable fibrinolysis inhibitor (TAFIa), which cleaves C-terminal lysine residues from the fibrin surface, thereby decreasing its cofactor activity. TAFI can be activated by thrombin alone, but the rate of activation is accelerated when in complex with thrombomodulin. Plasmin is also known to activate TAFI. TAFIa has no known physiologic inhibitors and consequently, its primary regulatory mechanism involves its intrinsic thermal instability. The rate of TAFI activation and stability of the active form, TAFIa, function in maintaining its concentration above the threshold value required to down-regulate fibrinolysis. Although all methods to quantify TAFI or TAFIa have their limitations, epidemiologic studies have indicated that elevated TAFI levels are correlated with an increased risk of venous thrombosis. Major efforts have been made to develop TAFI inhibitors that can either directly interfere with TAFIa activity or impair its activation. However, the anti-inflammatory properties of TAFIa might complicate the development and application of a TAFIa inhibitor that aims to increase the efficiency of thrombolytic therapy.

Measuring the mechanical properties of blood clots formed via the tissue factor pathway of coagulation.

Thrombelastography (TEG) is a method that is used to conduct global assays that monitor fibrin formation and fibrinolysis and platelet aggregation in whole blood. The purpose of this study was to use a well-characterized tissue factor (Tf) reagent and contact pathway inhibitor (corn trypsin inhibitor, CTI) to develop a reproducible thrombelastography assay. In this study, blood was collected from 5 male subjects (three times). Clot formation was initiated in whole blood with 5 pM Tf in the presence of CTI, and fibrinolysis was induced by adding tissue plasminogen activator (tPA). Changes in viscoelasticity were then monitored by TEG. In quality control assays, our Tf reagent, when used at 5 pM, induced coagulation in whole blood in 3.93 ± 0.23 min and in plasma in 5.12 ± 0.23 min (n=3). In TEG assays, tPA significantly decreased clot strength (maximum amplitude, MA) in all individuals but had no effect on clot time (R time). The intraassay variability (CVa<10%) for R time, angle, and MA suggests that these parameters reliably describe the dynamics of fibrin formation and degradation in whole blood. Our Tf reagent reproducibly induces coagulation, making it an ideal tool to quantify the processes that contribute to mechanical clot strength in whole blood.

Characteristics of fibrin formation and clot stability in individuals with congenital type IIb protein C deficiency.

Many studies have shown that unregulated or excessive thrombin formation is potentially a cause of thrombosis; however, studies examining processes that contribute to fibrin stabilization in individuals predisposed to thrombosis are limited. In this study, we investigate a family with familial thrombosis via type IIb protein C (PC) deficiency. Using contact pathway inhibited whole blood, thrombin generation, fibrin clot formation and factor (f)XIII activation were monitored over time in control (n=5) and PC deficient (n=4, 34 - 69% PC by activity) subjects. The dynamics of thrombin generation varied significantly with the time required to reach the maximal rate of thrombin-antithrombin formation being much shorter in PC deficiency (5.8 ± 0.4 minutes) than in controls (9.7 ± 0.4 minutes; p < 0.001). PC deficient clots were significantly heavier than control clots (p < 0.001) and this difference could not be contributed exclusively to differences in fibrinogen levels between groups. FXIII was consumed faster in PC deficient subjects (23.7 ± 2.0 nM/minute) than in controls (5.1 ± 1.5 nM/minute; p < 0.0001) suggesting increased fXIII activation and incorporation of fXIIIa substrates into the clot. In plasma, the clot lysis time was increased in PC deficiency by both TAFIa dependent and independent mechanisms. Since PC deficient clots are both denser and show a greater degree of resistance to fibrinolysis, these clots would likely resist fibrinolysis and potentiate fibrin deposition observed in thrombosis.

Thrombin activatable fibrinolysis inhibitor activation and bleeding in haemophilia A.

Individuals with haemophilia A exhibit bleeding tendencies that are not always predicted by their factor (F)VIII level. It has been suggested that bleeding in haemophilia is due not only to defective prothrombin activation but also aberrant fibrinolysis. Thrombin activatable fibrinolysis inhibitor (TAFI) activation was measured in tissue factor (TF)-initiated blood coagulation in blood samples of 28 haemophiliacs and five controls. Reactions were quenched over time with FPRck and citrate and assayed for TAFIa and thrombin-antithrombin (TAT). The TAFIa potential (TP), TAFI activation rate and the TAFIa level at 20 min (TAFIa(20 min)) was extracted from the TAFI activation progress curve. In general, the time course of TAFI activation follows thrombin generation regardless of FVIII activity and as expected the rate of TAFI activation and TP decreases as FVIII decreases. The magnitude of TP was similar among the control subjects and subjects with <11% FVIII. In severe subjects with <1% FVIII at the time of blood collection, the TAFIa(20 min) was inversely and significantly correlated with haemarthrosis (-0.77, P = 0.03) and total bleeds (-0.75, P = 0.03). In all cases, TAFIa(20 min) was more strongly correlated with bleeding than TAT levels at 20 min. Overall, this study shows that TAFI activation in whole blood can be quantified and related to the clinical bleeding phenotype. Measuring TAFIa along with thrombin generation can potentially be useful to evaluate the differential bleeding phenotype in haemophilia A.

Factor XIII combined with recombinant factor VIIa: a new means of treating severe hemophilia A.

BACKGROUND: Abnormal thrombin generation is considered the key defect in hemophilia. Conventional treatment seeks to correct this using coagulation factor replacement or bypassing agents, for example recombinant factor VIIa (rFVIIa). Previous studies demonstrate abnormal FXIII activation in patients with hemophilia. FXIII activation is essential for formation of structurally normal, stable clots. OBJECTIVES: The present study challenges the hypothesis that in hemophilia the use of plasma-derived FXIII (pdFXIII) in combination with rFVIIa will produce a greater improvement in clot stability than promotion of thrombin generation alone. METHODS: Fourteen individuals with severe hemophila A were enrolled. Whole blood was spiked ex vivo with buffer, rFVIIa (2 µg mL(-1)) or rFVIIa (2 µg mL(-1)) plus pdFXIII (10 µg mL(-1)). Whole blood thromboelastometry assessed clot stability, after activation with tissue factor (TF) (0.15 pm) plus tissue-type plasminogen activator (tPa) (2 nm). The primary outcome measure of clot stability was area under the elasticity curve (AUEC). RESULTS: The combination of pdFXIII and rFVIIa significantly improved clot stability as measured by AUEC (P < 0.05) compared with rFVIIa alone. CONCLUSION: The use of pdFXIII resulted in superior clot stability compared with solely enhancing thrombin generation and we suggest that increasing thrombin generation alone fails to fully correct dysregulation of clot-stabilizing mechanisms associated with bleeding disorders. Hemorrhage control in hemophilia may be improved using clot stabilizing drugs. FXIII shows potential as a novel agent.

Soluble thrombomodulin partially corrects the premature lysis defect in FVIII-deficient plasma by stimulating the activation of thrombin activatable fibrinolysis inhibitor.

BACKGROUND: Previous work by others has shown that premature clot lysis occurs in plasmas deficient in components of the intrinsic pathway, due to a failure to activate thrombin activatable fibrinolysis inhibitor (TAFI). This suggests the hypothesis that bleeding in hemophilia is due not only to defective coagulation but also enhanced fibrinolysis. These studies were carried out to quantify the extent of TAFI activation over time in normal plasma (NP) and factor VIII deficient plasma (FVIII-DP) and to determine whether soluble thrombomodulin (sTM) can correct the lysis defect in FVIII-DP. METHODS: The time courses of TAFI activation in both NP and FVIII-DP were monitored after clotting with thrombin, PCPS and Ca(2+), +/- sTM. Clotting and lysis were measured turbidometrically and TAFIa using a functional assay. RESULTS: Premature lysis that occurs in FVIII-DP is corrected by mixing deficient plasma with 10% NP. However, this does not fully correct the defect in TAFI activation. FVIII-DP must be mixed with up to 50% NP to attain the same TAFIa potential as NP. In FVIII-DP, sTM can correct the defect in TAFIa-dependent prolongation of lysis at low tPA concentrations and partially correct this defect at high tPA concentrations. CONCLUSIONS: TAFI activation increases as the concentration of FVIII increases. FVIII at a level of 10% fully corrects the lysis defect in spite of the extent of TAFI activation being only one half that obtained with 100% FVIII. In addition, sTM increases TAFI activation sufficiently to correct the premature lysis defect in FVIII-DP.