Reduced activity of TAFI (thrombin-activatable fibrinolysis inhibitor) in acute promyelocytic leukaemia

Paraneoplastic Hyperfibrinolysis: Detection of Occult Prostate Cancer with 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography

Hyperfibrinolysis caused by abnormal over-activation of the fibrinolytic system can be associated with occult cancer. We present an interesting case of a 48-year-old man with paraneoplastic hyperfibrinolysis, where ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography-computed tomography (PET-CT) was able to detect occult prostate-specific antigen-negative metastatic prostate cancer as the underlying etiology. This shows that while ¹⁸F-FDG PET-CT has overall poor sensitivity for prostate cancer, it can be useful in certain clinical situations.

Investigation of fibrinogen in early bleeding of patients with newly diagnosed acute promyelocytic leukemia

Early hemorrhagic death remains a major cause of treatment failure in acute promyelocytic leukemia (APL). This study investigated the role of fibrinogen concentrations in early hemorrhage and overall survival (OS) of APL patients. Laboratory and clinical data, including fibrinogen concentrations and other coagulation indexes, bleeding events, and survival data, of 198 patients newly diagnosed with APL from February 2012 to December 2017 were extracted from patient records and retrospectively investigated. Patients with moderate/severe bleeding had significantly lower median fibrinogen concentrations (p = .023), higher Chinese disseminated intravascular coagulation scoring system (CDSS) (p < .001), and were more often female (p = .034) than patients with no such bleeding. Additionally, patients with fibrinogen <1.0 g/L and 1.0-1.6 g/L had significantly higher moderate/severe bleeding rates than those with fibrinogen >1.6 g/L (p = .015; p = .023). However, moderate/severe (p = .088) and severe bleeding rates (p = .063) were comparable for patients with fibrinogen <1.0 g/L and 1.0-1.6 g/L. Multivariate analysis showed that fibrinogen ≤1.6 g/L (p = .036), platelet counts ≤10 × 10⁹/L (p = .037), and CDSS scores ≥5 (p = .023) were independent risk factors for moderate/severe bleeding. Survival analysis indicated that moderate/severe bleeding (p = .018), fibrinogen ≤1.6 g/L combined with prothrombin time >12.8 s (p = .005), age ≥60 years (p = .001), and CDSS ≥5 (p = .044) were independent predictors of 1-year OS. Fibrinogen ≤1.6 g/L may be an independent risk factor for early bleeding in newly treated patients with APL and is associated with a worse 1-year OS. Increasing fibrinogen to >1.6 g/L may help to prevent bleeding.

Hemorrhagic disorders of fibrinolysis: a clinical review

Hyperfibrinolytic bleeding can be caused by a deficiency of one of the inhibitors of fibrinolysis (plasminogen activator inhibitor type 1 [PAI-1] or α2-antiplasmin [α2-AP]), or an excess of one of the activators of fibrinolysis: tissue-type plasminogen activator or urokinase-type plasminogen activator. This review focuses on the clinical implications of these disorders. The bleeding phenotype of fibrinolytic disorders is characterized by delayed bleeding after trauma, surgery and dental procedures. Bleeding in areas of high fibrinolytic activity is also common, such as menorrhagia and epistaxis. Patients with α2-AP deficiency present with the most severe bleeding episodes. Recently, it was discovered that hyperfibrinolytic disorders are associated with a high rate of obstetric complications such as miscarriage and preterm birth, especially in PAI-1 deficient patients. Hyperfibrinolytic disorders are probably underdiagnosed because of lack of knowledge and lack of accurate diagnostic tests. A substantial part of the large group of patients diagnosed as 'bleeding of unknown origin' could actually have a hyperfibrinolytic disorder. In the case of a high index of suspicion (i.e. because of a positive family history, recurrent bleeding or uncommon type of bleeding such as an intramedullary hematoma), further testing should not be withheld because of normal results of standard hemostatic screening assays. Timely diagnosis is important because these disorders can generally be treated well with antifibrinolytic agents.

Hyperfibrinolysis Is an Important Cause of Early Hemorrhage in Patients with Acute Promyelocytic Leukemia

Background

The objective of the current study was to guide the early clinical treatment strategies by assessing the recovery of abnormal coagulation in acute promyelocytic leukemia (APL) patients during induction therapy.

Material/Methods

Retrospective analysis was performed in 112 newly-diagnosed patients with APL during induction treatment.

Results

The early death (ED) rate in our study was 5.36% and the main cause was fetal hemorrhage. The presence of bleeding symptoms was significantly correlated with low platelet and fibrinogen levels. The values of white blood cell (WBC), lactate dehydrogenase (LDH), prothrombin time (PT), fibrinogen, and bone marrow leukemic promyelocyte in the high-risk group were significantly different from those in the low/intermediate-risk groups. Coagulation variables significantly improved after dual induction therapy. No significant difference was found in changes of platelet (PLT), prothrombin time (PT), activated partial thromboplastin time (APTT), D-dimers, and fibrinogen among different risk groups after induction therapy. D-dimer levels were initially high and remained well above normal after 4 weeks of induction therapy.

Conclusions

Aggressive prophylactic transfusion to maintain high platelet and fibrinogen transfusion thresholds could reduce hemorrhage in APL patients. Immediately starting induction therapy effectively alleviated coagulopathy in APL patients. Hyperfibrinolysis was a more important event in the APL hemorrhagic diathesis.

Retinoic acid and arsenic trioxide in the treatment of acute promyelocytic leukemia: current perspectives

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia (AML) with a unique morphological appearance, associated coagulopathy and canonical balanced translocation of genetic material between chromosomes 15 and 17. APL was first described as a distinct subtype of AML in 1957 by Dr Leif Hillestad who recognized the pattern of an acute leukemia associated with fibrinolysis, hypofibrinogenemia and catastrophic hemorrhage. In the intervening years, the characteristic morphology of APL has been described fully with both classical hypergranular and variant microgranular forms. Both are characterized by a balanced translocation between the long arms of chromosomes 15 and 17, [t(15;17)(q24;q21)], giving rise to a unique fusion gene PML-RARA and an abnormal chimeric transcription factor (PML-RARA), which disrupts normal myeloid differentiation programs. The success of current treatments for APL is in marked contrast to the vast majority of patients with non-promyelocytic AML. The overall prognosis in non-promyelocytic AML is poor, and although there has been an improvement in overall survival in patients aged <60 years, only 30%-40% of younger patients are still alive 5 years after diagnosis. APL therapy has diverged from standard AML therapy through the empirical discovery of two agents that directly target the molecular basis of the disease. The evolution of treatment over the last 4 decades to include all-trans retinoic acid and arsenic trioxide, with chemotherapy limited to patients with high-risk disease, has led to complete remission in 90%-100% of patients in trials and rates of overall survival between 86% and 97%.

Bleeding related to disturbed fibrinolysis

The components and reactions of the fibrinolysis system are well understood. The pathway has fewer reactants and interactions than coagulation, but the generation of a complete quantitative model is complicated by the need to work at the solid‐liquid interface of fibrin. Diagnostic tools to detect disease states due to malfunctions in the fibrinolysis pathway are also not so well developed as is the case with coagulation. However, there are clearly a number of inherited or acquired pathologies where hyperfibrinolysis is a serious, potentially life‐threatening problem and a number of antifibrinolytc drugs are available to treat hyperfibrinolysis. These topics will be covered in the following review.

Plasma Thrombin-activatable Fibrinolysis Inhibitor Levels Correlate with the Disease Activity of Ulcerative Colitis

Objective Patients with ulcerative colitis (UC) are at an increased risk for thromboembolic events, particularly in patients with extensive and active disease. To date, a few studies have been published on the role of thrombin-activatable fibrinolysis inhibitor (TAFI) in UC. However, there are no reports in the literature investigating the effect of UC treatment on plasma TAFI levels. Methods The plasma TAFI antigen levels were quantitatively determined using ELISA kits for 20 UC patients at activation and remission, along with 17 healthy controls. The association between the TAFI levels and inflammatory markers was assessed to determine UC activation. To predict and determine the activation of UC, the Truelove-Witts index and the endoscopic activation index (EAI) were used for each subject. Results The plasma TAFI levels were higher in UC patients at activation of the disease compared with the remission state and in healthy controls. Spearman's correlation analyses revealed that the WBC (r: 0.586, p<0.001), hsCRP (r: 0.593, p<0.001) and EAI (r: 0.721, p<0.001) were significantly correlated with the TAFI levels. The overall accuracy of TAFI in determining UC activation was 82.5% with a sensitivity, specificity, NPV and PPV of 80%, 85%, 81% and 84.2%, respectively (cut-off value: 156.2% and AUC: 0.879). Conclusion The present study demonstrates that the TAFI levels are elevated in the active state of UC. The assessment of TAFI levels in patients with UC in conjunction with other markers of inflammation may provide additional information for estimating UC activation and severity.

Induction, consolidation, and maintenance therapies with arsenic as a single agent for acute promyelocytic leukaemia in a 11-year follow-up

The aim of this study was to evaluate the effect of arsenic trioxide as a single agent in acute promyelocytic leukaemia cases for induction, consolidation, and maintenance therapy in a long-term, 11-year follow-up. We studied 60 patients with acute promyelocytic leukaemia. Sixty percent of the patients were aged between 12 and 24 years. Arsenic trioxide was infused at a 0.15 mg/kg daily dose until complete remission was achieved. After 2 weeks of rest, arsenic trioxide was infused daily for 28 days as a consolidation therapy. Then, arsenic infusions were given every 3-4 months for 14 days for 2 years, and the patients were followed until relapse or death. The rates of complete remission, disease-free survival, overall survival, and drug toxicity were evaluated. The morphologic complete remission was observed in 55 out of the 60 patients. The most common causes of a remission failure were early mortality because of the APL differentiation syndrome and the lack of response to arsenic treatment. The mean follow-up was 90 months. The primary outcomes for males and females were a mean disease-free survival of 101 and 97 months, respectively, and a mean overall survival of 103 and 101 months, respectively. From the 55 cases with remission, three patients died (late mortality). Of the 60 patients, 85% are still alive. Arsenic trioxide was generally well tolerated. The long-term follow-up of patients with APL, treated with arsenic alone as induction, consolidation, and maintenance therapy, shows high cure rates and excellent outcomes. Copyright © 2015 John Wiley & Sons, Ltd.

Thrombomodulin alfa treatment in patients with acute promyelocytic leukemia and disseminated intravascular coagulation: a retrospective analysis of an open-label, multicenter, post-marketing surveillance study cohort

INTRODUCTION

Patients with acute promyelocytic leukemia (APL) can develop disseminated intravascular coagulation (DIC) that results in life-threatening hemorrhagic complications. Studies regarding the safety and efficacy of thrombomodulin alfa (TM-α; recombinant human soluble thrombomodulin) in patients with APL and DIC are limited.

MATERIALS AND METHODS

A retrospective evaluation was performed on a cohort of 172 patients with APL from an open-label, multicenter, post-marketing surveillance study of TM-α.

RESULTS

Of the 172 patients, 31 were relapse/refractory APL patients, and 141 were newly diagnosed APL patients. Within the first 30 days, 24 patients (14.0%) died, and six of those deaths (3.5%) were due to hemorrhage. In total, 12 patients (7.0%) had severe hemorrhagic complications. Both the early death rate due to hemorrhage as well as the severe hemorrhage rate did not exceed those in some recent population-based studies of patients with APL. Forty-nine patients received TM-α prior to the initiation of antileukemic treatment, and one patient experienced hemorrhagic early death (ED), suggesting that early TM-α treatment appeared to result in a reduction in the hemorrhagic ED rate. Moreover, TM-α improved coagulopathy regardless of concomitant all-trans retinoic acid treatment.

CONCLUSIONS

This study confirmed the safety and efficacy of TM-α in daily clinical practice for patients with APL and DIC. TM-α appeared to reduce hemorrhagic early deaths due to DIC in patients with APL who were receiving antileukemic treatment.

Pathogenesis of disseminated intravascular coagulation in patients with acute promyelocytic leukemia, and its treatment using recombinant human soluble thrombomodulin

Acute promyelocytic leukemia (APL) is an uncommon subtype of acute myelogenous leukemia characterized by the proliferation of blasts with distinct morphology, a specific balanced reciprocal translocation t(15;17), and life-threatening hemorrhage caused mainly by enhanced fibrinolytic-type disseminated intravascular coagulation (DIC). The introduction of all-trans retinoic acid (ATRA) into anthracycline-based induction chemotherapy regimens has dramatically improved overall survival of individuals with APL, although hemorrhage-related death during the early phase of therapy remains a serious problem. Moreover, population-based studies have shown that the incidence of early death during induction chemotherapy is nearly 30 %, and the most common cause of death is associated with hemorrhage. Thus, development of a novel treatment strategy to alleviate abnormal coagulation in APL patients is urgently required. Recombinant human soluble thrombomodulin (rTM) comprises the active extracellular domain of TM, and has been used for treatment of DIC since 2008 in Japan. Use of rTM in combination with remission induction chemotherapy, including ATRA, produces potent resolution of DIC without exacerbation of bleeding tendency in individuals with APL. This review article discusses the pathogenesis and features of DIC caused by APL, as well as the possible anticoagulant and anti-leukemic action of rTM in APL patients.

Management of bleeding in the terminally ill patient

Clinically significant bleeding occurs in approximately 6%-10% of patients in the palliative-care setting. Bleeding can range from persistent and small in quantity (but enough to interfere with a patient's quality of life), to catastrophic bleeding that ultimately leads to the rapid demise of the patient. Uncontrolled bleeding can be very distressing for staff, patients and families. Advanced planning is necessary in all bleeding circumstances. This session will review the types of cancer associated with bleeding, as well as management options for these situations. Emphasis will be placed on aspects of communication with families.

Molecular basis for the diagnosis and treatment of acute promyelocytic leukemia

Acute promyelocytic leukemia is characterized by gene rearrangements that always involve the retinoic acid receptor alpha on chromosome 15. In the majority of patients t(15;17) is detected, which generates the promyelocytic leukemia gene/retinoic acid receptor alpha rearrangement. This rearrangement interacts with several proteins, including the native promyelocytic leukemia gene, thus causing its delocalization from the nuclear bodies, impairing its function. The immunofluorescence staining technique using the anti-PML antibody may be used to provide a rapid diagnosis and to immediately start therapy using all-trans retinoic acid. The experience of the International Consortium on Acute Promyelocytic Leukemia has demonstrated that early mortality was significantly reduced by adopting the immunofluorescence technique. All-trans retinoic acid combined with chemotherapy is the standard therapy; this promotes complete remission rates greater than 90% and cure rates of nearly 80%. However, early mortality is still an important limitation and hematologists must be aware of the importance of treating newly diagnosed acute promyelocytic leukemia as a medical emergency.

Methionine-induced hyperhomocysteinemia reverts fibrinolytic pathway activation in a murine model of acute promyelocytic leukemia

Increased fibrinolysis is an important component of acute promyelocytic leukemia (APL) bleeding diathesis. APL blasts overexpress annexin II (ANXII), a receptor for tissue plasminogen activator (tPA), and plasminogen, thereby increasing plasmin generation. Previous studies suggested that ANXII plays a pivotal role in APL coagulopathy. ANXII binding to tPA can be inhibited by homocysteine and hyperhomocysteinemia can be induced by L-methionine supplementation. In the present study, we used an APL mouse model to study ANXII function and the effects of hyperhomocysteinemia in vivo. Leukemic cells expressed higher ANXII and tPA plasma levels (11.95 ng/mL in leukemic vs 10.74 ng/mL in wild-type; P = .004). In leukemic mice, administration of L-methionine significantly increased homocysteine levels (49.0 μmol/mL and < 6.0 μmol/mL in the treated and nontreated groups, respectively) and reduced tPA levels to baseline concentrations. The latter were also decreased after infusion of the LCKLSL peptide, a competitor for the ANXII tPA–binding site (11.07 ng/mL; P = .001). We also expressed and purified the p36 component of ANXII in Pichia methanolica. The infusion of p36 in wild-type mice increased tPA and thrombin-antithrombin levels, and the latter was reversed by L-methionine administration. The results of the present study demonstrate the relevance of ANXII in vivo and suggest that methionine-induced hyperhomocysteinemia may reverse hyperfibrinolysis in APL.

Thrombin activatable fibrinolysis inhibitor and thrombin-antithrombin-III-complex levels in patients with gastric cancer

The relation between cancer and coagulation is the subject of investigation since a relation between tumor and thrombosis has been determined. Antithrombin III is an important thrombin inhibitor, and increased thrombin-antithrombin (TAT) complex levels activate coagulation. Activated thrombin activatable fibrinolysis inhibitor (TAFI) inhibits the conversion of plasminogen to plasmin. In addition, it directly inactivates plasmin. Defective fibrinolysis increases the risk of thrombosis. In this study, we evaluated homeostatic parameters, TAFI, and TAT levels in patients with gastric cancer applying to the medical oncology outpatient clinic. Fifty-two patients and 35 healthy controls were included. ELISA was used to measure TAFI and TAT complex levels. These were statistically higher in the patient group (p < 0.05 and p = 0.001, respectively). D-dimer levels were higher in stage IV (p = 0.05). Correlations between lymph nodes and TAFI and TAT levels were examined. Weak but positive correlation between lymph nodes and TAFI was detected (R = 0.452, p = 0.027). TAFI and TAT levels were evaluated using relative operating characteristic analysis to differentiate the disease. TAT was more specific than TAFI according to this analysis (TAFI area under curve (AUC), 0.676; TAT AUC, 0.874). Thrombotic events and bleeding disorders need to be borne in mind in gastric cancer. This situation is due to the impairment of the balance between coagulation and fibrinolysis. Further studies are now needed to evaluate the effects of TAFI and TAT on survey and prognosis as well as the potential of these parameters as tumor markers for gastric cancer.

Thrombin-activatable fibrinolysis inhibitor in breast cancer patients

OBJECTIVE

To evaluate the levels of thrombin-activatable fibrinolysis inhibitor (TAFI) activity and also its relationship with other homeostasis markers in breast cancer patients.

SUBJECTS AND METHODS

Forty-two female patients with breast cancer and 24 healthy women (controls) were enrolled in the study and fasting blood samples of all cases were drawn from a large antecubital vein for assay of TAFI and other homeostasis tests.

RESULTS

The TAFI levels were 79.5 ± 15.5 and 39.3 ± 12.1 in patients and controls, respectively, and the difference was statistically significant (p < 0.001). In the patient group, the serum fibrinogen level was 504.9 ± 224.8, while in the control group it was 393.9 ± 100.5, and the difference was also statistically significant (p < 0.001).

CONCLUSION

The data showed that increased levels of TAFI are a contributing factor of thrombotic disorders in breast cancer patients.

Elevated levels of activated and inactivated thrombin-activatable fibrinolysis inhibitor in patients with sepsis

BACKGROUND

In sepsis, large scale inflammatory responses can cause extensive collateral damage to the vasculature, because both coagulation and fibrinolysis are activated unevenly. Thrombin-activatable fibrinolysis inhibitor (TAFI) plays a role in modulating fibrinolysis. Since TAFI can be activated by both thrombin and plasmin, it is thought to be affected in sepsis. Hence, activated and inactivated TAFI (TAFIa/ai) may be used to monitor changes in sepsis.

METHODS

TAFIa/ai-specific in-house ELISA can detect only the TAFIa/ai form, because the ELISA capture agent is potato tuber carboxypeptidase inhibitor (PTCI), which has selective affinity towards only the TAFIa and TAFIai isoforms. TAFIa/ai levels in plasma from 25 patients with sepsis and 19 healthy volunteers were quantitated with the in-house ELISA.

RESULTS

We observed increased TAFIa/ai levels in samples from patients with sepsis (48.7±9.3 ng/mL) than in samples from healthy individuals (10.5±5.9 ng/mL). In contrast, no difference in total TAFI concentration was obtained between sepsis patients and healthy controls. The results suggest that TAFI zymogen was activated and that TAFIa/ai accumulated in sepsis.

CONCLUSION

The detection of TAFIa/ai in plasma could provide a useful and simple diagnostic tool for sepsis. Uneven activation of both coagulation and fibrinolysis in sepsis could be caused by the activation of TAFI zymogen and elevation of TAFIa/ai. TAFIa/ai could be a novel marker to monitor sepsis and other blood-related disturbances.

The role of plasminogen-plasmin system in cancer

Components of the plasminogen-plasmin system participate in a wide variety of physiologic and pathologic processes, including tumor growth, invasion and metastasis, through their effect on angiogenesis and cell migration. These components are found in most tumors and their expression not only signifies their function but also carries a prognostic value. Their expression is in turn modulated by cytokines and growth factors, many of which are up-regulated in cancer. Though both tPA and uPA are expressed in tumor cells, uPA with its receptor (uPAR) is mostly involved in cellular functions, while tPA with its receptor Annexin II on endothelial surface, regulates intravascular fibrin deposition. Among the inhibitors of fibrinolysis, PAI-1 is a major player in the pathogenesis of many vascular diseases as well as in cancer. Therapeutic interventions, either using plasminogen activators or experimental inhibitor agents against PAI-1, have shown encouraging results in experimental tumors but not been verified clinically.

Plasma thrombin activatable fibrinolysis inhibitor and tissue factor pathway inhibitor changes following sepsis

Sepsis-induced systemic inflammation results in coagulation abnormalities that may be different in gram-positive and gram-negative infections. We used ciprofloxacin to induce a predominantly gram-positive Enterococcus faecalis polymicrobial sepsis in rats. Ciprofloxacin-untreated rats exhibited a predominantly gram-negative polymicrobial sepsis. Rats were subjected to 30% body surface area burn (B), cecal ligation puncture (CLP) with a 22-gauge needle, and B + CLP. Ciprofloxacin-treated B + CLP rats showed a significant decrease in plasma thrombin activatable fibrinolysis inhibitor (TAFI) levels compared with sham rats. However, plasma tissue factor pathway inhibitor (TFPI) levels decreased significantly in B, CLP, and B + CLP groups compared with sham rats. The ciprofloxacin-untreated group showed a significant decrease in plasma TAFI levels in CLP and B + CLP and plasma TFPI levels decreased in all 3 groups compared with sham rats. Histological changes in the liver and kidney included vascular congestion and parenchyma bleed following B + CLP in ciprofloxacin-untreated rats. These results suggest that plasma TAFI and TFPI levels differ depending on the type of bacteria involved in the septic process.

The 1040C/T polymorphism influencing thermal stability and activity of thrombin activatable fibrinolysis inhibitor is associated with risk for oral cancer

No studies thus far have investigated the contribution of thrombin activatable fibrinolysis inhibitor (TAFI) to oral oncogenesis. We studied the activity-related 1040C/T polymorphism in 150 patients with oral cancer and 138 healthy controls matched by age, gender, and ethnicity. The increased-activity T allele frequency was significantly reduced in patients compared with controls (28.7% vs. 37.0%, P < 0.05). T/T homozygotes had about half the probability of developing oral cancer (O.R. 0.39, 95%C.I. 0.13-1.14), while no significant difference was observed in C/T heterozygotes. The observed prophylactic effect of increased TAFI activity might result from reduction of plasmin and inhibition of extracellular matrix dissolution.

Thrombin activatable fibrinolysis inhibitor (TAFI): A role in pre-eclampsia?

Pre-eclampsia (P-Ec) is a complex multisystem disorder of unknown aetiology reported to occur in about 6% to 8% of all pregnancies throughout the world. This disease is associated with fibrin deposition and occlusive lesions in placental vessels. Pro-thrombin activatable fibrinolysis inhibitor (pro-TAFI) is a relatively recently described glycoprotein that can be converted into its active form (TAFIa) by thrombin, thrombin-thrombomodulin and plasmin. TAFIa potentially inhibits fibrinolysis by removing C-terminal lysine and arginine residues from fibrin. These residues are required for adsorption of tissue-type plasminogen activator (t-PA) and plasminogen to fibrin. Therefore, TAFIa decreases plasmin formation and protects the fibrin clot against lysis. An increased of pro-TAFI/TAFIa levels has been reported in some clinical conditions associated with thrombotic tendency, as type II diabetes mellitus, deep vein thrombosis and symptomatic artery disease. Few studies have investigated pro-TAFI/TAFIa in normal or complicated pregnancy but contrasting results were reported. Understanding the role of pro-TAFI/TAFIa in the pathogenesis of P-Ec can hold great promise for improving P-Ec management. In this context, a large-scale study evaluating plasma TAFI antigen and activity, its synthesis and metabolism in pre-eclamptic women is required. Recently new selective TAFIa inhibitors have been developed. The design of a new therapy to treat and/or prevent P-Ec, based on successful use of TAFIa inhibitors, may have significant clinical ramifications.

Quantification of the effects of thrombin activatable fibrinolysis inhibitor and α2-antiplasmin on fibrinolysis in normal human plasma

Two major proteins that inhibit fibrinolysis include thrombin activatable fibrinolysis inhibitor (TAFI) and alpha2-antiplasmin. Our goal was to quantify the contribution of TAFI and alpha2-antiplasmin to antifibrinolytic defenses with thrombelastography. Plasma activated with tissue factor/kaolin was subjected to fibrinolysis with tissue-type plasminogen activator (100 U/ml). Prior to activation, TAFI activity was inhibited with either potato carboxypeptidase inhibitor (25 microg/ml) or an anti-TAFI antibody, and alpha2-antiplasmin activity was inhibited with an anti-alpha2-antiplasmin antibody. Data were collected for 30 min, with the time of onset and rate of fibrinolysis determined. Compared with uninhibited samples, TAFI inhibition significantly (P < 0.05) decreased the time of onset of fibrinolysis by 70% and increased the rate of lysis by 70%. There was no difference between potato carboxypeptidase inhibitor and anti-TAFI antibody inhibition. Inhibition of alpha2-antiplasmin resulted in a significantly (P < 0.05) decreased time of onset (85%) and increased the rate of lysis (557%) compared with uninhibited samples. Inhibition of alpha2-antiplasmin activity resulted in a significantly (P < 0.05) greater fibrinolytic response than TAFI inhibition. In conclusion, utilization of standard inhibitors and thrombelastography permitted quantification of the effects of TAFI and alpha2-antiplasmin on fibrinolysis in plasma. Future investigation of diseases involving hypofibrinolysis (e.g. left ventricular assist devices) could be conducted using this assay system.

Evolution of Thrombin Formation and Fibrinolysis Markers, Including Thrombin-Activatable Fibrinolysis Inhibitor, during Severe Meningococcemia

A 17-year-old girl presented with Neisseria meningitidis sepsis, with evidence of disseminated intravascular coagulation. Substitution therapy with both antithrombin and protein C concentrates was initiated, leading to clinical and biological improvement. Sequential dosages were performed for biological markers including thrombin-activatable fibrinolysis inhibitor (TAFI). Substitution therapy with both antithrombin and protein C concentrates led to a clinical and biological improvement. Biological markers showed a decrease in thrombin generation and in plasminogen activator inhibitor 1 (PAI-1) and a return of TAFI to a normal value. Discontinuation of substitutive treatment was marked by a clinical relapse at 24 h, with thrombin generation and increase in PAI-1, while TAFI remained unchanged. This report shows the evolution of hemostasis markers during septic shock and provides new data concerning the effects of a substitutive therapy.

Plasma TAFI and soluble CD40 ligand do not predict reperfusion following thrombolysis for acute myocardial infarction

INTRODUCTION

Thrombolytic therapy fails to achieve reperfusion in almost a third of patients with acute myocardial infarction. Thrombin activatable fibrinolysis inhibitor (TAFI) and soluble CD40 ligand (sCD40L) are novel endogenous fibrinolytic and atherothrombotic factors that determine clot stability. We investigated whether admission plasma thrombin activatable fibrinolysis inhibitor (TAFI) and soluble CD40 ligand (sCD40L) concentrations predicted reperfusion following thrombolytic therapy in patients with acute myocardial infarction.

MATERIALS AND METHODS

Prior to administration of thrombolytic therapy, venous blood was collected from 110 patients presenting with acute ST segment elevation myocardial infarction and plasma assayed for tissue plasminogen activator (t-PA) antigen and activity, plasminogen activator inhibitor type-1 antigen (PAI-1), TAFI antigen and activity, C-reactive protein (CRP) and sCD40L concentrations. Reperfusion was determined using continuous ST segment monitoring.

RESULTS

Reperfusion occurred in 77 (70%) patients with a mean treatment to reperfusion time of 83 +/- 46 min. Peak creatine kinase was significantly lower in patients who reperfused (1578 +/- 1199 versus 2200 +/- 1744 U/L; P < 0.05) and correlated with time to reperfusion (r = 0.44 [95% CI: 0.23 - 0.61], P = 0.0001). There was a modest correlation between plasma TAFI antigen and activity (r = 0.3 [95% CI: 0.04 - 0.53]; P < 0.05). There were no significant associations between coronary reperfusion and plasma concentrations of t-PA, PAI-1, TAFI, CRP or sCD40L.

CONCLUSIONS

Systemic plasma TAFI, sCD40L and CRP concentrations do not predict reperfusion in patients receiving thrombolytic therapy for acute ST elevation myocardial infarction.

TAFI and PAI-1 levels in human sepsis

BACKGROUND

Plasminogen activator inhibitor type-1 (PAI-1) is considered to be the main inhibitor of fibrinolysis in sepsis. However, the contribution of TAFI to the inhibition of fibrinolysis in sepsis is currently unknown.

METHODS

TAFI antigen and PAI-1 levels were measured in severe sepsis (n = 32) and septic shock (n = 8) patients. In addition, TAFI antigen levels had been determined in 151 controls.

RESULTS

Septic patients had significantly (p < 0.0001) decreased TAFI levels (median: 78.9% [range: 32.4-172.6]) as compared to controls (108.1% [35.9-255.4]). TAFI levels were equal in septic shock and severe sepsis (68.9% [32.4-172.6] vs. 82.5% [32.7-144.9], p = 0.987) as well as in survivors and non-survivors (87.1% [32.7-172.6] vs. 65.8% [32.4-129.5], p = 0.166). PAI-1 levels were significantly (705.5 ng/ml [131-5788]) higher in septic shock as in severe sepsis patients (316.5 ng/ml [53-1311], p = 0.016) and were equal in survivors and non-survivors (342 ng/ml [53-1311] vs. 413 ng/ml [55-5788], p = 0.231). TAT/PAP ratio (R((TAT/PAP))) reflecting the dysbalance between coagulation and fibrinolysis was calculated. R((TAT/PAP)) significantly increased with fatality and was significantly dependent on PAI-1, but not on TAFI. PAI-1 levels (570.5 ng/ml [135-5788]) and R((TAT/PAP)) (1.6 [0.3-6.1]) were significantly (p = 0.008 and p = 0.047) higher in patients with overt DIC as compared to patients without overt DIC (310 ng/ml [53-1128] and 0.6 [0.1-4.3]), whereas no difference was found for TAFI levels (68.9% [32.7-133.2] vs. 86.4% [32.4-172.6], p = 0.325).

CONCLUSIONS

Although inhibition in sepsis is mediated by both, PAI-1 might be involved early in the sepsis process, whereas TAFI might be responsible for ongoing fibrinolysis inhibition in later stages of sepsis.

Plasma antigen levels of thrombin-activatable fibrinolysis inhibitor did not differ in patients with or without disseminated intravascular coagulation

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a carboxypeptidase that downregulates fibrinolysis and might play some roles in the pathogenesis of disseminated intravascular coagulation (DIC). We prospectively examined the plasma TAFI antigen levels in patients highly suspected to be suffering from DIC. Patients were subdivided into overt DIC and non-DIC groups according to a DIC scoring system. The Sepsis-related Organ Failure Assessment (SOFA) scores were concurrently calculated on patients with sepsis. Overall, there were 23 non-DIC patients and 20 patients with overt DIC. Their baseline characteristics were similar, but patients with overt DIC had much more aberrant coagulation tests and higher lactate dehydrogenase levels. However, there was no significant difference between overt DIC and non-DIC patients regarding their TAFI antigen levels [median/interquartile range (IQR) 74.41/13.98 and 75.29/15.16, respectively, p=0.543]. On regression analysis, TAFI antigen levels were not correlated with either C-reactive protein levels or various coagulation test results. In patients with sepsis (n=31), TAFI levels among three risk groups stratified by low (<or=5), intermediate (6-10), and high (>or=11) SOFA scores were not statistically disparate (median/IQR 65.24/15.14, 74.63/13.79, and 75.29/21.51, respectively, p=0.684), either. Our result indicated that plasma TAFI antigen levels did not vary significantly between patients with or without DIC. Further, they did not possess any correlation with the severity of organ injury in patients with sepsis. The role of TAFI antigen in the pathogenesis of DIC needs further elucidation by future studies.

Tissue factor pathway inhibitor and thrombin activatable fibrinolytic inhibitor plasma levels following burn and septic injuries in rats

Burn and septic injuries induce profound changes in coagulation status. This study examined the changes in plasma tissue factor pathway inhibitor (TFPI) and thrombin activatable fibrinolytic inhibitor (TAFI) levels in a rat model of burn and septic injuries. Rats underwent 30% TBSA cutaneous scald burn injury and septic insult was induced by caecal ligation and puncture (CLP). CLP was superimposed on burn injury to mimic the clinical model of sepsis complicating burn injury. Rats were pretreated with Cprofloxacin orally to colonize their gut with Enterococcus faecalis. TFPI and TAFI plasma levels were measured using functional activity assay kit with a chromogenic method at 24 and 72 hours following the injuries. TFPI levels decreased significantly at 24 hours in burn, CLP, and burn+CLP groups, followed by incomplete rebound recovery at 72 hours in all three groups. On the other hand, TAFI levels increased significantly at 24- and 72-hour time points in all three groups. These results suggest that burn, septic, and their combined injuries perturb coagulation cascade and thrombotic process toward the procoagulant pathway by impairing fibrinolysis.

Thrombin activatable fibrinolysis inhibitor in Behçet's disease

INTRODUCTION

Thrombin activatable fibrinolysis inhibitor (TAFI) is a procarboxypeptidase downregulating plasmin formation, thereby causing a tendency for thrombosis development. Since, Behçet's disease (BD) is a systemic vasculitis, which is commonly complicated by arterial and venous thrombosis, we aimed to find out plasma TAFI levels in BD, compared with healthy controls. We also searched whether plasma TAFI levels were significantly different between Behçet's subgroups with and without thrombosis.

MATERIALS AND METHODS

In this study, 105 BD patients (M/F: 64/41; mean age 36+/-1 years), followed up by Ege University Rheumatology Department were enrolled. The exclusion criteria were hemophilia, hyperlipidemia, diabetes mellitus, hepatic diseases renal failure, antiphospholipid positivity, oral contraceptive use and pregnancy. Age-and sex-matched healthy controls (n=53) were also included. Plasma TAFI levels were measured by ELISA. Since TAFI is also an acute-phase reactant, we also measured other inflammatory markers such as C-reactive protein (CRP).

RESULTS

Plasma TAFI levels were significantly higher in Behçet's patients (91.1+/-7.4 ng/ml) compared with healthy controls (14.3+/-4.5 ng/ml) (P<0.001), but there were no significant difference between the subgroups with and without thrombosis. In BD, there was no correlation between plasma TAFI levels and CRP.

CONCLUSIONS

Regardless of manifest thrombosis, plasma TAFI levels in BD were significantly higher than in healthy controls. High TAFI levels might possibly contribute to the thrombotic tendency in BD. Future studies investigating TAFI gene polymorphism and functional activity are clearly needed, to clarify the exact role of TAFI in Behçet's thrombosis.

Assessment of thrombin-activatable fibrinolysis inhibitor (TAFI) plasma levels in inflammatory bowel diseases

OBJECTIVES

Hypofibrinolysis has been proposed as a possible mechanism underlying the known risk of thrombosis observed in patients with inflammatory bowel diseases (IBD). Thrombin-activatable fibrinolysis inhibitor (TAFI) is a recently described inhibitor of fibrinolysis. Increased TAFI plasma levels are associated with a risk for venous thrombosis. The objective was to evaluate TAFI plasma levels and their possible correlations with clinical features and acute-phase reactants in IBD patients.

METHODS

Eighty-one IBD patients (47 Crohn's disease and 34 ulcerative colitis) and 81 sex- and age-matched healthy controls were enrolled in the study; moreover, we studied 30 inflammatory controls (13 Reiter's syndrome, 4 Behçet's syndrome, and 13 patients with newly diagnosed celiac disease). TAFI plasma levels were assessed by means of a commercially available ELISA kit. Erythrocytes sedimentation rate, C-reactive protein, and alpha1-acid glycoprotein were measured as acute-phase reactants. Statistical analysis was performed by means of nonparametric tests and Fisher's exact test and chi(2) test for independence.

RESULTS

Median TAFI plasma levels were significantly higher in IBD patients (116.0%, range: 39.0-232.0%) and in inflammatory controls (176.0%, 50.0-435.0%) than in healthy controls (99.0%, 40.0-170.0%) (p< or = 0.05 and p< or = 0.001, respectively). TAFI plasma levels higher than the 95th percentile of control values were significantly more frequent in IBD patients (19.7%) and in inflammatory controls (53.3%) than in healthy controls (4.9%) (p< or = 0.008 and p< or = 0.0001, respectively) and more frequent in clinically active IBD than in clinically quiescent IBD (31.4%vs 10.9%, p< or = 0.03). Finally, in IBD, significant correlations were observed between TAFI plasma levels and erythrocytes sedimentation rate (p< or = 0.02), C-reactive protein (p< or = 0.001), and alpha1-acid glycoprotein (p< or = 0.05).

CONCLUSIONS

TAFI plasma levels are increased in IBD patients and correlate with acute-phase reactants. Increased TAFI plasma levels might contribute to the prothrombotic state observed in IBD through the induction of hypofibrinolysis.

Tumor growth and metastasis are not affected in thrombin-activatable fibrinolysis inhibitor-deficient mice

Many studies have indicated that the plasminogen activation system may have a prominent role in cancer. Activation of the zymogen plasminogen into the serine protease plasmin by plasminogen activator is mediated by carboxyterminal basic amino acids in fibrin, including lysines and arginines. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a circulating carboxypeptidase B-type proenzyme that, after activation, removes carboxyterminal lysine or arginine residues in fibrin, resulting in decreased plasminogen activation and attenuated fibrinolysis. To determine directly whether TAFI is involved in primary tumor growth and metastasis formation, we examined the effects of TAFI deficiency on subcutaneous growth and experimentally or spontaneously induced pulmonary metastasis formation of different tumor cell types in mice. In all tumor models TAFI deficiency did not affect the formation and growth of primary and metastasized tumors.

New insights into factors affecting clot stability: a role for thrombin activatable fibrinolysis inhibitor (TAFI; plasma procarboxypeptidase B, plasma procarboxypeptidase U, procarboxypeptidase R)

The thrombin-catalyzed conversion of plasma fibrinogen into fibrin and the development of an insoluble fibrin clot are the final steps in the coagulation cascade during hemostasis. The delicate balance between clot formation and fibrinolysis, which determines clot stability, is controlled by a complex interplay between fibrin and other molecular and cellular components of the hemostatic system, including thrombin activatable fibrinolysis inhibitor (TAFI). TAFI is activated by thrombin and has an important role in the stability of the fibrin clot, which is reviewed here. In particular, the role of TAFI in fibrinolysis and those characteristics of the protein that affect clot stability are described. In addition, the importance of TAFI in the coagulation process and how changes in its availability may contribute to bleeding or thrombotic disorders are discussed.

Thrombin and fibrinolysis

When the activities of the coagulation and fibrinolytic cascades are properly regulated, so that fibrin (FN) deposition and removal are properly balanced, the vascular system is protected from catastrophic blood loss at the site of an injury, while its fluidity is ensured elsewhere. When these activities are not properly regulated, however, the organism is subjected to either excessive bleeding or thrombosis. Thrombomodulin on the endothelial cell is very important in this regulation because it converts thrombin to an anticoagulant enzyme by directing it toward the activation of protein C. It also converts thrombin to an antifibrinolytic enzyme by directing it toward the activation of thrombin-activatable fibrinolysis inhibitor (TAFI). By doing so, it creates a direct molecular connection between the coagulation and fibrinolytic cascades, such that activation of the former suppresses the activity of the latter. Recent studies indicate that the TAFI pathway functions in vivo and is likely relevant in maintaining the proper balance between FN deposition and removal. Whether it will be a target for pharmaceutical manipulation of this balance remains to be determined.

Thrombin-activatable fibrinolysis inhibitor (TAFI, plasma procarboxypeptidase B, procarboxypeptidase R, procarboxypeptidase U)

Recently, a new inhibitor of fibrinolysis was described, which downregulated fibrinolysis after it was activated by thrombin, and was therefore named TAFI (thrombin-activatable fibrinolysis inhibitor; EC 3.4.17.20). TAFI turned out to be identical to the previously described proteins, procarboxypeptidase U, procarboxypeptidase R, and plasma procarboxypeptidase B. Activated TAFI (TAFIa) downregulates fibrinolysis by the removal of carboxy-terminal lysines from fibrin. These carboxy-terminal lysines are exposed upon limited proteolysis of fibrin by plasmin and act as ligands for the lysine-binding sites of plasminogen and tissue-type plasminogen activator (t-PA). Elimination of these lysines by TAFIa abrogates the fibrin cofactor function of t-PA-mediated plasminogen activation, resulting in a decreased rate of plasmin generation and thus downregulation of fibrinolysis. In this review, the characteristics of TAFI are summarized, with an emphasis on the pathways leading to activation of TAFI and the role of TAFIa in the inhibition of fibrinolysis. However, it cannot be ruled out that TAFI has other, as yet undefined, functions in biology.

A pulmonary syndrome in patients with acute myelomonocytic leukemia and inversion of chromosome 16

Different subtypes of acute myelogenous leukemia have distinct clinical presentations and courses. The specific clinical and molecular aspects of these leukemias have helped modify and create specific strategies for their management. We observed an increased incidence of pulmonary complications in patients with acute myelomonocytic leukemias (AMML) with inversion of chromosome 16 [inv(16)] irrespective of the presence of hyperleukocytosis. We reviewed patient records available over a period of 12 years at The Cleveland Clinic Foundation of patients with AMML with inv(16) and compared the incidence of pulmonary complications to a matched control group of patients with AMML but without inv(16). We found an increased incidence of pulmonary complications in the AMML with inv(16)group when compared to the control group. Two of these patients demonstrated brochiolitis obliterans with organizing pneumonia (BOOP) on lung biopsy. No specific etiology for the pulmonary complications was identified. These findings represent the first observation of an association between WHO-AMML with inv(16) [FAB-AML M4 with inv(16)] with a pulmonary syndrome at presentation. BOOP should be suspected in these cases. A larger prospective study to evaluate this association is warranted.

cDNA microarray gene expression profiling of hydroxyurea, paclitaxel, and p-anisidine, genotoxic compounds with differing tumorigenicity results

The potential application of toxicogenomics to predictive toxicology has been discussed widely, but the utility of the approach remains largely unproven. Using cDNA microarrays, we compared the gene expression profiles produced in mouse lymphoma cells by three genotoxic compounds, hydroxyurea (a carcinogen), p-anisidine (a noncarcinogen), and paclitaxel (carcinogenicity unknown). To minimize the effect of biological variability and technological limitations, quadruplicate observations were made for each compound and a subset of genes yielding reproducible induction/repression was selected for comparison. A method was applied to attach normalized expression data to genes with a low false-discovery rate (<0.1) to yield more confidence regarding differential expression. This analysis identified genotoxicity-specific gene expression. Seven genes were consistently upregulated and 12 downregulated more than 2-fold by the three genotoxic compounds. Using additional genes, the expression pattern induced by the genotoxic noncarcinogen, p-anisidine, was readily distinguished from that associated with the genotoxic carcinogen, hydroxyurea. Comparison of paclitaxel-induced expression data to data for p-anisidine and hydroxyurea suggested that paclitaxel's profile is more similar to the genotoxic noncarcinogen. With further supporting evidence it may be possible to perform large-scale monitoring of gene expression during drug and chemical development that can provide an early warning of potential toxicological responses.

Effect of anticoagulants in colorimetric assay for basic carboxypeptidases

Carboxypeptidases (CP) in plasma and sera serve as regulators of anaphylatoxins such as C3a and C5a. The activity of CP can be measured by determining hippuric acid after cleavage of the small synthetic substrate hippuryl-L-arginine. Although a colorimetric assay is convenient for determining hippuric acid generated by CP, we noticed that some anticoagulants, such as citrate, interfere with the color development of the reagents used. EDTA and heparin provide an appropriate value. EGTA used as anticoagulant also provides an appropriate value. Therefore, concentration of citrate in samples should be controlled to be constant for background subtraction.

Plasmin-mediated activation and inactivation of thrombin-activatable fibrinolysis inhibitor

Activated thrombin-activatable fibrinolysis inhibitor (TAFIa) attenuates the fibrin cofactor function of tissue-type plasminogen activator-mediated plasmin formation and subsequently fibrin degradation. In the present study, we focused on the role of plasmin in the regulation of TAFIa activity. Upon incubation with plasmin, TAFIa activity was generated, which was unstable at 37 degrees C. Analysis of the cleavage pattern showed that TAFI was cleaved at Arg(92), releasing the activation peptide from the 35.8-kDa catalytic domain. The presence of the 35.8-kDa fragment paralleled the time course of generation and loss of TAFIa activity. This suggested that, in the presence of plasmin, TAFIa is probably inactivated by proteolysis rather than by conformational instability. TAFI was also cleaved at Arg(302), Lys(327), and Arg(330), resulting in a approximately 44.3-kDa fragment and several smaller fragments. The 44.3-kDa fragment is no longer activatable since it lacks part of the catalytic center. We concluded that plasmin can cleave at several sites in TAFI and that this contributes to the regulation of TAFI and TAFIa.

Thrombin-activatable fibrinolysis inhibitor antigen and TAFI activity in patients with APC resistance caused by factor V Leiden mutation

Thrombin-activatable fibrinolysis inhibitor (TAFI), also known as procarboxypeptidase U or plasma procarboxypeptidase B, is a relatively recently described plasma glycoprotein synthesised in the liver. It can be activated into active enzyme TAFIa (carboxypeptidase U or plasma carboxypeptidase B) by a complex of thrombin/thrombomodulin. TAFIa can potentially inhibit fibrinolysis by removing carboxyterminal lysine residues from partially degraded fibrin, decreasing plasminogen binding on the surface of fibrin, which thereby results in a decrease of the fibrinolytic activity. Since TAFI represents a connection between coagulation and fibrinolysis, it can be expected that TAFI levels are altered in different thrombotic and hemorrhagic diseases. Thrombin generation is increased in patients with activated protein C (APC) resistance, while it has been shown that APC has profibrinolytic effect. Therefore, changes in TAFI level should be found in patients with APC resistance due to factor V Leiden (FV Leiden) mutation. TAFI antigen (including TAFI, TAFIa and the inactive form TAFIai) and TAFI activity were determined in 17 female patients heterozygous for FV Leiden mutation while 13 healthy volunteers were controls. No statistically significant difference in levels of TAFI antigen was observed. TAFI activity was significantly reduced in APC resistance patients compared to control (P=.018). The nondifference in TAFI antigen, together with the decrease of TAFI activity level, can be explained by activation of TAFI to TAFIa and shifting of equilibrium towards an increase of the latter. This can be an indirect proof that TAFIa is increased in patients with APC resistance due to FV Leiden mutation, indicating that downregulation of fibrinolysis can be an additional risk factor for thrombosis in these patients.

Total thrombin-activatable fibrinolysis inhibitor (TAFI) antigen and pro-TAFI in patients with haemophilia A

Pro-thrombin-activatable fibrinolysis inhibitor (pro-TAFI), also known as TAFI, procarboxypeptidase U, or procarboxypeptidase B, is a relatively recently described plasma glycoprotein synthesized in the liver. It can be catalysed into its active form, TAFI (TAFIa, carboxypeptidase U or B) by a complex of thrombin/thrombomodulin. TAFI can potentially inhibit fibrinolysis by removing carboxyterminal lysine residues from partially degraded fibrin, decreasing plasminogen binding on the surface of fibrin, which thereby results in a decrease of the fibrinolytic activity. As TAFI represents a connection between coagulation and fibrinolysis, it can be expected that TAFI levels are altered in different thrombotic and haemorrhagic diseases, such as haemophilia A. Total TAFI antigen (including pro-TAFI, TAFI and the inactive form of TAFI [TAFIi]) and pro-TAFI were determined in 17 patients with haemophilia A. Thirteen healthy age-matched volunteers served as controls. No significant difference in levels of total TAFI antigen was observed between controls and patients with haemophilia, although it was slightly decreased in patients with haemophilia. Pro-TAFI was significantly reduced in haemophilia patients compared to controls (P=0.0113). TAFI antigen levels similar to controls have already been described in different clinical conditions, including haemophilia A. Decrease of pro-TAFI in haemophilia A can be an additional factor, together with decrease in thrombin generation, which induces impaired activation of pro-TAFI to TAFI, and could cause accelerated fibrinolysis. This supports the validity of usage of antifibrinolytics in the treatment of haemophilia A. In this paper we use new nomenclature for TAFI, and we believe that this recommended terminology for different forms of TAFI can simplify further standardization in TAFI investigation.

Activity and antigen levels of thrombin-activatable fibrinolysis inhibitor in plasma of patients with disseminated intravascular coagulation

We measured the plasma levels of thrombin-activatable fibrinolysis inhibitor (TAFI) activity and antigen in patients with disseminated intravascular coagulation (DIC) to examine the relationship between hypofibrinolysis and the pathogenesis of DIC. TAFI activity and antigen levels in the plasma were both significantly low in patients with DIC. TAFI activity in plasma was correlated with TAFI antigen, indicating that activity and antigen correspond well. The decrease of TAFI activity in DIC may be due to enhanced consumption. Since the plasma thrombin-antithrombin III complex (TAT) level was found to be elevated in DIC, increase of thrombomodulin-thrombin complex generation is suggested in this state. TAFI activity and antigen levels were negatively correlated with TAT and D-dimer, suggesting that the plasma levels of TAFI are reduced by thrombin generation. Since TAFI was not correlated with fibrinogen, plasma-alpha(2)plasmin inhibitor complex (PPIC) and tissue type plasminogen activator/plasminogen activator inhibitor-1 (tPA/PAI-1) complex, TAFI might be a secondary modulator of fibrinolysis. The TAFI activity in plasma was significantly low in patients with infection and in those with organ failure, suggesting that TAFI may play an important role in the mechanism of organ failure in DIC-associated sepsis. In brief, TAFI may play an important role in the pathogenesis of DIC and organ failure.

Clinical experience of arsenic trioxide in relapsed acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) has unique clinical, cytogenetic, and molecular features and is one of the most potentially curable human malignancies. The current standard treatment given to patients with newly diagnosed APL consists of all-trans retinoic acid and anthracycline-based cytotoxic chemotherapy, which is highly effective for remission induction. However, despite the potential for cure with existing treatments, approximately 20%-30% of patients relapse and require salvage therapy. Reports of the safety and efficacy of arsenic trioxide from centers in China led to a pivotal trial of this agent in the United States for patients with relapsed APL. In an initial pilot study, 11 of 12 patients experienced a complete response, and a subsequent multicenter trial confirmed the efficacy and safety of arsenic trioxide for remission induction in this patient population. Additional trials are under way to evaluate the use of this agent alone or as part of a chemotherapy regimen for consolidation and maintenance of patients with APL.