Antipsychotic drugs as a risk factor for venous thromboembolism

Objective. We assessed whether antipsychotic drugs represent a risk factor for venous thromboembolism by comparing the prevalence of antipsychotic drugs use in a population of patients with venous thromboembolism versus a group of individuals treated for hypertension. Methods. We identified 266 patients (141 women) diagnosed as having venous thromboembolism at the average age of 43.1±11 years who had been hospitalized in the University Hospital in Hradec Králové from 1 January 1996 to 31 December 2004. Two hundred and seventy-four patients (140 women) with arterial hypertension, with an average age of 48.3±8.8 years, represented the control population. Results. Use of antipsychotic drugs was moderately more frequent in the group of patients with venous thromboembolism as compared with the control group subjects (4.89 vs. 1.82%; odds ratio 2.76; 95% confidence interval=1.01-7.55). Discussion. We discuss the possible mechanisms of venous thromboembolism induced by antipsychotic agents - hypoactivity, blood status, obesity, abnormal coagulation, autoimmune mechanisms, and hyperhomocysteinemia. Conclusion. Our results indicate the possibility of an increased risk for venous thromboembolism in patients using antipsychotic drugs. It is necessary to seriously consider this possible adverse effect owing to its potentially fatal consequences.

The plasma hemostatic proteome: thrombin generation in healthy individuals

BACKGROUND AND OBJECTIVES

The range of plasma concentrations of hemostatic analytes in the population is wide. In this study these components of blood coagulation phenotype are integrated in an attempt to predict clinical risk.

METHODS

We modeled tissue factor (TF)-induced thrombin generation in the control population (N = 473) from the Leiden Thrombophilia Study utilizing a numerical simulation model. Hypothetical thrombin generation curves were established by modeling pro- and anticoagulant factor levels for each individual. These curves were evaluated using parameters which describe the initiation, propagation and termination phases of thrombin generation, i.e. time to 10 nm thrombin (approximate clot time), total thrombin and the maximum rates and levels of thrombin generated.

RESULTS AND CONCLUSIONS

The time to 10 nm thrombin varied over a 3-fold range (2.9-9.5 min), maximum levels varied over a approximately 4-fold range (200-800 nm), maximum rates varied approximately 4.8-fold (90-435 nm min(-1)) and total thrombin varied approximately 4.5-fold (39-177 microm s(-1)) within this control population. Thrombin generation curves, defined by the clotting factor concentrations, were distinguished by sex, age, alcohol consumption, body mass index (BMI) and oral contraceptive (OC) use (OC > sex > BMI > age). Our results show that the capacity for thrombin generation in response to a TF challenge may represent a method to identify an individual's propensity for developing thrombosis.

Effects of isoflurane, sevoflurane, and desflurane on platelet function: A prospective, randomized, single-blind, in vivo study

BACKGROUND

The primary physiologic function of platelets is to facilitate hemostasisby aggregation. Volatile anesthetics have been reported to decrease platelet aggregation in vivo and in vitro.

OBJECTIVE

The aim of this study was to investigate the hematologic effectsof the anesthetics isoflurane, sevoflurane, and desflurane on hemoglobin (Hb), hematocrit (Hct), platelet count, activated partial thromboplastin time (aPTT), prothrombin time (PT), international normalized ratio (INR), and platelet aggregation after minor surgery.

METHODS

Patients aged 20 to 60 years who were scheduled to undergominor surgery and American Society of Anesthesiologists physical status P1 or P2 (healthy or mild systemic disease) were randomized to 1 of 3 groups: 1 minimum alveolar concentration (MAC) of isoflurane, sevoflurane, or desflurane. None of the patients received premedication. Anesthesia was induced using IV thiopental 5 to 6 mg/kg, fentanyl 1 to 2 μg/kg, and vecuronium 0.1 mg/kg, and maintained with 1 MAC of isoflurane, sevoflurane, or desflurane in 66% nitrous oxide and 33% oxygen. Vecuronium 0.03 mg/kg was given when necessary for muscle relaxation. All patients were monitored throughout surgery; isotonic saline was given at a rate of 5 mL/kg · h. Hematologic studies were performed preoperatively, 15 minutes after intubation, and 1 hour after the end of surgery. Platelet aggregation tests were performed in a laboratory using a platelet function analyzer (PFA), collagen/epinephrine PFA test cartridges, collagen/adenosine diphosphate PFA test cartridges, and PFA trigger solution.

RESULTS

This prospective, randomized, single-blind, in vivo study was conducted at Gevher Nesibe Teaching Hospital, Erciyes University, Kayseri, Turkey. Thirty patients (15 men, 15 women) were randomized to the 3 treatment groups (each, n = 10). Hb, Hct, platelet count, aPTT, PT, and INR were statistically similar between all 3 groups. The measured parameters were not significantly different between the isoflurane and desflurane groups at any time point. However, in the sevoflurane group, mean (5D) platelet aggregation was significantly delayed 15 minutes after intubation and 1 hour after surgery compared with the preoperative values (collagen/epinephrine, 81.70 [9.85] seconds vs 196.20 [27.84] seconds and 115.40 [25.80] seconds; both, P < 0.05).

CONCLUSIONS

In this study of the effects of isoflurane, sevoflurane, and desflurane in patients undergoing minor surgery, clinically relevant antithrombotic effects were observed 15 minutes after intubation with all 3 drugs, although the effects in patients receiving sevoflurane were significantly greater compared with those in patients receiving isoflurane and desflurane. The antithrombotic effects of isoflurane and desflurane were not continued at 1 hour after surgery; however, the inhibitory effects of sevoflurane on platelet function were continued at 1 hour after surgery but were significantly decreased from levels found at 15 minutes after intubation.

Transfusion of post-operative shed blood: laboratory characteristics and clinical utility

Increased awareness of the potential hazards of allogenic blood transfusion, such as incompatibility reactions, metabolic and immunologic disorders, or transmission of viral diseases, has led to an emphasis on allogeneic blood alternatives. For orthopaedic surgery, several autologous transfusion modalities have emerged as alternatives to allogeneic blood transfusion, avoiding its immunomodulatory effects. Among them, transfusion or return of post-operative salvaged shed blood has become popular in major orthopaedic procedures. However, although the effectiveness of this blood-saving method is well documented, several authors have questioned its safety and recommended the use of washed blood. Therefore, this review analyses the haematologic characteristics of unwashed filtered shed blood, including metabolic status and survival of red blood cells, the components of the haemostatic system, the content of fat particles, bacterial and tumour cells and the possibility of their removal, the content of inflammatory mediators, and the effects on the patient's immune system. From data reviewed in this paper, it can be concluded that post-operative salvage of blood seems to be an excellent source of functional and viable red cells without many of the transfusion-related risks and with some immuno-stimulatory effects. In addition, from our experience, post-operative re-infusion of unwashed shed blood after major spine procedures has proved to reduce post-operative homologous transfusion requirements and to complement pre-operative autologous blood donation, without any clinically relevant complication.

Inhibition of the tissue factor pathway of coagulation by recombinant nematode anticoagulant protein c2 during elective coronary stent implantation

BACKGROUND

Exposure of tissue factor (TF) to the circulation during coronary stent implantation initiates coagulation activation and may contribute to the risk of thrombotic complications. In this study, we investigated whether inhibition of TF-factor VIIa by recombinant Nematode Anti-coagulant Protein c2 (rNAPc2) is able to suppress haemostatic and inflammatory activity in patients undergoing elective intracoronary stenting.

METHODS

In a randomised, double-blind design, 102 patients received either placebo or rNAPc2 (biological half-life >50 hours) at doses of 3.5, 5.0, 7.5 and 10.0 μg/kg as a single subcutaneous administration two to six hours before angioplasty. All patients also received aspirin, clopidogrel and unfractionated heparin (activated clotting time >250 seconds during angioplasty). Serial blood samples were collected before and after the intervention.

RESULTS

At 30 hours after stenting, all rNAPc2 treatment groups but not the placebo group demonstrated a reduction from baseline of prothrombin fragment F1+2 and D-dimer plasma levels (to 23 and 12% below baseline values at the highest dose, respectively), which were significantly lower in three rNAPc2 groups compared with placebo (p≤0.03). TF plasma levels were initially reduced in all rNAPc2 groups and returned to baseline values 18 hours after stent implantation. These three markers all increased to above baseline values in the placebo group. Levels of P-selectin, antithrombin III and interleukin-8 were not or only slightly affected by the intervention or by rNAPc2, whereas a significant 2.8 to 4.1 fold increase of C-reactive protein plasma levels was found in all patient groups after the procedure.

CONCLUSION

In contrast to the inflammatory response, coagulation activation after elective coronary stent implantation, which is observed in spite of the use of multiple antithrombotic drugs, can be attenuated by inhibition of the TF-factor VIIa complex using rNAPc2. Inhibition of the TF-mediated pathway of coagulation may be an important target to prevent thrombotic complications after coronary stenting.

Bench-to-bedside review: functional relationships between coagulation and the innate immune response and their respective roles in the pathogenesis of sepsis

The innate immune response system is designed to alert the host rapidly to the presence of an invasive microbial pathogen that has breached the integument of multicellular eukaryotic organisms. Microbial invasion poses an immediate threat to survival, and a vigorous defense response ensues in an effort to clear the pathogen from the internal milieu of the host. The innate immune system is able to eradicate many microbial pathogens directly, or innate immunity may indirectly facilitate the removal of pathogens by activation of specific elements of the adaptive immune response (cell-mediated and humoral immunity by T cells and B cells). The coagulation system has traditionally been viewed as an entirely separate system that has arisen to prevent or limit loss of blood volume and blood components following mechanical injury to the circulatory system. It is becoming increasingly clear that coagulation and innate immunity have coevolved from a common ancestral substrate early in eukaryotic development, and that these systems continue to function as a highly integrated unit for survival defense following tissue injury. The mechanisms by which these highly complex and coregulated defense strategies are linked together are the focus of the present review.

Bench-to-bedside review: endothelial cell dysfunction in severe sepsis: a role in organ dysfunction?

During the past decade a unifying hypothesis has been developed to explain the vascular changes that occur in septic shock on the basis of the effect of inflammatory mediators on the vascular endothelium. The vascular endothelium plays a central role in the control of microvascular flow, and it has been proposed that widespread vascular endothelial activation, dysfunction and eventually injury occurs in septic shock, ultimately resulting in multiorgan failure. This has been characterized in various models of experimental septic shock. Now, direct and indirect evidence for endothelial cell alteration in humans during septic shock is emerging. The present review details recently published literature on this rapidly evolving topic.

The lectin-like domain of thrombomodulin confers protection from neutrophil-mediated tissue damage by suppressing adhesion molecule expression via nuclear factor kappaB and mitogen-activated protein kinase pathways

Thrombomodulin (TM) is a vascular endothelial cell (EC) receptor that is a cofactor for thrombin-mediated activation of the anticoagulant protein C. The extracellular NH(2)-terminal domain of TM has homology to C-type lectins that are involved in immune regulation. Using transgenic mice that lack this structure (TM(LeD/LeD)), we show that the lectin-like domain of TM interferes with polymorphonuclear leukocyte (PMN) adhesion to ECs by intercellular adhesion molecule 1-dependent and -independent pathways through the suppression of extracellular signal-regulated kinase (ERK)(1/2) activation. TM(LeD/LeD) mice have reduced survival after endotoxin exposure, accumulate more PMNs in their lungs, and develop larger infarcts after myocardial ischemia/reperfusion. The recombinant lectin-like domain of TM suppresses PMN adhesion to ECs, diminishes cytokine-induced increase in nuclear factor kappaB and activation of ERK(1/2), and rescues ECs from serum starvation, findings that may explain why plasma levels of soluble TM are inversely correlated with cardiovascular disease. These data suggest that TM has antiinflammatory properties in addition to its role in coagulation and fibrinolysis.

Interdomain engineered disulfide bond permitting elucidation of mechanisms of inactivation of coagulation factor Va by activated protein C

Procoagulant factor Va (FVa) is inactivated via limited proteolysis at three Arg residues in the A2 domain by the anticoagulant serine protease, activated protein C (APC). Cleavage by APC at Arg306 in FVa causes dissociation of the A2 domain from the heterotrimeric A1:A2:A3 structure and complete loss of procoagulant activity. To help distinguish inactivation mechanisms involving A2 domain dissociation from inactivation mechanisms involving unfavorable changes in factor Xa (FXa) affinity, we used our FVa homology model to engineer recombinant FVa mutants containing an interdomain disulfide bond (Cys609-Cys1691) between the A2 and A3 domains (A2-SS-A3 mutants) in addition to cleavage site mutations, Arg506Gln and Arg679Gln. SDS-PAGE analysis showed that the disulfide bond in A2-SS-A3 mutants prevented dissociation of the A2 domain. In the absence of A2 domain dissociation from the A1:A2:A3 trimer, APC cleavage at Arg306 alone caused a sevenfold decrease in affinity for FXa, whereas APC cleavages at Arg306, Arg506, and Arg679 caused a 70-fold decrease in affinity for FXa and a 10-fold decrease in the k(cat) of the prothrombinase complex for prothrombin without any effect on the apparent K(m) for prothrombin. Therefore, for FVa inactivation by APC, dissociation of the A2 domain may provide only a modest final step, whereas the critical events are the cleavages at Arg506 and Arg306, which effectively inactivate FVa before A2 dissociation can take place. Nonetheless, for FVa Leiden (Gln506-FVa) inactivation by APC, A2 domain dissociation may become mechanistically important, depending on the ambient FXa concentration.

Plasma fibrin D-dimer levels correlate with tumour volume, progression rate and survival in patients with metastatic breast cancer

Plasma levels of D-dimer are elevated in cancer patients. Activation of the extrinsic coagulation system and the fibrinolytic cascade within a tumour is thought to be related with growth, invasion and metastasis. We have investigated the relationship between these markers of fibrin metabolism, standard clinicopathological variables and serum levels of angiogenic cytokines in three cohorts: group A (n=30) consisted of 30 healthy female volunteers, group B (n=23) of consecutive patients with operable breast cancer and group C (n=84) of patients with untreated or progressive metastatic breast cancer. Plasma D-dimers, fibrinogen, IL-6, vascular endothelial growth factor and calculated vascular endothelial growth factor load in platelets are clearly increased in patients with breast cancer. D-dimers were increased in nearly 89% of patients with progressive metastatic disease. The level of D-dimers was positively correlated with tumour load (P<0.0001), number of metastatic sites (P=0.002), progression kinetics (P<0.0001) and the cytokines related to angiogenesis: serum vascular endothelial growth factor (P=0.0016, Spearman correlation=0.285), calculated vascular endothelial growth factor load in platelets (P<0.0001, Spearman correlation=0.37) and serum interleukin-6 (P<0.0001, Spearman correlation=0.59). Similarly increased D-dimer levels were positively correlated with increased fibrinogen levels (P<0.0001, Spearman correlation=0.38). The association between markers of fibrin degradation in patients with progressive breast cancer suggests that the D-dimer level is a clinically important marker for progression and points towards a relation between haemostasis and tumour progression. A role of interleukin-6, by influencing both angiogenesis and haemostasis, is suggested by these observations.

The role of high density lipoproteins in thrombosis

Lipids and lipoproteins, as well as factors involved in hemostasis and thrombosis, play a central role in the pathogenesis of cardio- and cerebrovascular disease. In recent years it has become clear that a strong association exists between coagulation factors and plasma lipoproteins. Anionic phospholipids are necessary for the optimal activity of both pro- and anticoagulant enzymatic complexes. Cell membranes have traditionally been considered to provide the essential lipid-containing surfaces. However, in light of recent studies, plasma lipoproteins are also believed to provide appropriate surfaces to support coagulation. While triglyceride-rich lipoproteins and oxidized low-density lipoproteins are associated with a procoagulant profile, high-density lipoproteins (HDL) may have an anticoagulant effect. This paper reviews scientific data on the potential role of HDL as modulator of thrombotic processes.

G20210A prothrombin gene mutation identified in patients with venous leg ulcers

The G20210A mutation variant of prothrombin gene is the second most frequent mutation identified in patients with deep venous thrombosis, after factor V Leiden. The risk for developing deep venous thrombosis is high in patients identified as heterozygous for G20210A mutation. In order to identify this polymorphism in the gene coding prothrombin, the 345bp fragment in the 3'- untranslated region of the prothrombin gene was amplified using amplification by polymerase chain reaction and enzymatic digestion by HindIII (restriction endonuclease enzyme). The products of amplification and enzymatic's digestion were analized using agarose gel electrophoresis. We investigated 20 patients with venous leg ulcers and we found 2 heterozygous (10%) for G20210A mutation. None of the patients in the control group had G20210A mutation. Our study confirms the presence of G20210A mutation in the Romanian population. Our study also shows the link between venous leg ulcers and this polymorphism in the prothrombin gene.

Blockade by ruthenium red of tissue factor-initiated coagulation

The ability of ruthenium red (RuR) to inhibit tissue factor (TF)-initiated blood coagulation was demonstrated at the protein and cellular levels as well as in human plasma. In a single-stage clotting assay, RuR concentration-dependently inhibited rabbit brain thromboplastin (rbTF)-induced coagulation and offset bacterial endotoxin (LPS)-induced monocytic TF (mTF) hypercoagulation; the IC(50)s were estimated at 7.5 and 12.3 microM, respectively. A 15-min preincubation of RuR with rbTF or monocyte suspension resulted in the pronounced inhibition with a significantly lowered IC(50) at 1.8 or 7.7 microM for rbTF or mTF procoagulation, respectively. The differences in IC(50)s between rbTF and mTF without or with the preincubation indicated that TF was a primary target for RuR action. The effect of RuR on the physiological function of TF in FVII activation was demonstrated by the proteolytic cleavage of FVII zymogen to its active forms of serine protease on Western blotting analyses. RuR readily blocked TF-catalyzed FVII activation (diminished FVIIa formation), thus down regulating the initiation of blood coagulation. Inclusion of RuR into human plasma samples in vitro significantly prolonged prothrombin time, indicating the depressed coagulation. FVII activity was inhibited by 30 - 60% depending on the dose; as a result, FX activity also decreased. However, RuR showed no effect on thrombin time. Thus, RuR inhibited FVII activation to block the initiation of coagulation.

The normal role of Activated Protein C in maintaining homeostasis and its relevance to critical illness

Thrombin is a multifunctional protein, with procoagulant, inflammatory and anticoagulant effects. Binding of thrombin to thrombomodulin results in activation of Protein C and initiation of the Activated Protein C anticoagulant pathway, a process that is augmented by the endothelial cell Protein C receptor (EPCR). Activated Protein C has demonstrated antithrombotic, anti-inflammatory, and profibrinolytic properties. Its antithrombotic activity is particularly important in the microcirculation, and Protein C deficiency is associated with microvascular thrombosis. Activated Protein C has also been shown to modulate inflammation. When the level of thrombomodulin or Protein C is reduced in sepsis there is a vicious cycle of coagulation and inflammation, with potentially lethal consequences. In vitro studies and animal models have shown that Activated Protein C blunts the inflammatory and coagulant response to sepsis through a variety of mechanisms.

Microvascular endothelial dysfunction: a renewed appreciation of sepsis pathophysiology

Severe sepsis, defined as sepsis associated with acute organ dysfunction, results from a generalized inflammatory and procoagulant host response to infection. Coagulopathy in severe sepsis is commonly associated with multiple organ dysfunction, and often results in death. The molecule that is central to these effects is thrombin, although it may also have anticoagulant and antithrombotic effects through the activation of Protein C and induction of prostacyclin. In recent years, it has been recognized that chemicals produced by endothelial cells play a key role in the pathogenesis of sepsis. Thrombomodulin on endothelial cells coverts Protein C to Activated Protein C, which has important antithrombotic, profibrinolytic and anti-inflammatory properties. A number of studies have shown that Protein C levels are reduced in patients with severe infection, or even in inflammatory states without infection. Because coagulopathy is associated with high mortality rates, and animal studies have indicated that therapeutic intervention may result in improved outcomes, it was rational to initiate clinical studies.

Tissue plasminogen activator-mediated fibrinolysis protects against axonal degeneration and demyelination after sciatic nerve injury

Tissue plasminogen activator (tPA) is a serine protease that converts plasminogen to plasmin and can trigger the degradation of extracellular matrix proteins. In the nervous system, under noninflammatory conditions, tPA contributes to excitotoxic neuronal death, probably through degradation of laminin. To evaluate the contribution of extracellular proteolysis in inflammatory neuronal degeneration, we performed sciatic nerve injury in mice. Proteolytic activity was increased in the nerve after injury, and this activity was primarily because of Schwann cell-produced tPA. To identify whether tPA release after nerve damage played a beneficial or deleterious role, we crushed the sciatic nerve of mice deficient for tPA. Axonal demyelination was exacerbated in the absence of tPA or plasminogen, indicating that tPA has a protective role in nerve injury, and that this protective effect is due to its proteolytic action on plasminogen. Axonal damage was correlated with increased fibrin(ogen) deposition, suggesting that this protein might play a role in neuronal injury. Consistent with this idea, the increased axonal degeneration phenotype in tPA- or plasminogen-deficient mice was ameliorated by genetic or pharmacological depletion of fibrinogen, identifying fibrin as the plasmin substrate in the nervous system under inflammatory axonal damage. This study shows that fibrin deposition exacerbates axonal injury, and that induction of an extracellular proteolytic cascade is a beneficial response of the tissue to remove fibrin. tPA/plasmin-mediated fibrinolysis may be a widespread protective mechanism in neuroinflammatory pathologies.

Protease-activated receptor 1 mediates thrombin-dependent, cell-mediated renal inflammation in crescentic glomerulonephritis

Protease-activated receptor (PAR)-1 is a cellular receptor for thrombin that is activated after proteolytic cleavage. The contribution of PAR-1 to inflammatory cell-mediated renal injury was assessed in murine crescentic glomerulonephritis (GN). A pivotal role for thrombin in this model was demonstrated by the capacity of hirudin, a selective thrombin antagonist, to attenuate renal injury. Compared with control treatment, hirudin significantly reduced glomerular crescent formation, T cell and macrophage infiltration, fibrin deposition, and elevated serum creatinine, which are prominent features of GN. PAR-1-deficient (PAR-1(-/-)) mice, which have normal coagulation, also showed significant protection from crescentic GN compared with wild-type mice. The reductions in crescent formation, inflammatory cell infiltration, and serum creatinine were similar in PAR-1(-/-) and hirudin-treated mice, but hirudin afforded significantly greater protection from fibrin deposition. Treatment of wild-type mice with a selective PAR-1-activating peptide (TRAP) augmented histological and functional indices of GN, but TRAP treatment did not alter the severity of GN in PAR(-/-) mice. These results indicate that activation of PAR-1 by thrombin or TRAP amplifies crescentic GN. Thus, in addition to its procoagulant role, thrombin has proinflammatory, PAR-1-dependent effects that augment inflammatory renal injury.

Enhanced expression of genes involved in coagulation and fibrinolysis in murine arthritis

STATEMENT OF FINDINGS: We have analyzed the pattern of procoagulant and fibrinolytic gene expression in affected joints during the course of arthritis in two murine models. In both models, we found an increased expression of tissue factor, tissue factor pathway inhibitor, urokinase plasminogen activator, and plasminogen activator inhibitor 1, as well as thrombin receptor. The observed pattern of gene expression tended to favor procoagulant activity, and this pattern was confirmed by functional assays. These alterations would account for persistence of fibrin within the inflamed joint, as is seen in rheumatoid arthritis.

The imbalance between coagulation and fibrinolysis is related to the severity of the illness and the prognosis in sepsis

OBJECTIVES

The coagulation and fibrinolytic system appears to be activated by the septic process independently, leading to the syndrome of disseminated intravascular coagulation (DIC). In this study, we investigated the changes within the hemostatic system related to the severity of the illness and the prognosis in patients with sepsis.

METHODS

Plasma thrombin-antithrombin III (TAT) and plasmin-alpha 2-antiplasmin (PAP) complexes were measured using ELISA methods in 32 patients with sepsis and 20 controls and were analyzed according to the APACHE III scores and survival of the patients.

RESULTS

Plasma TAT and PAP in patients with sepsis were significantly higher than controls. Nonsurvivors showed greater levels of TAT (21.7 +/- 22.3 ng/mL) and lower levels of PAP (628.4 +/- 378.1 ng/mL) than survivors (TAT: 11.1 +/- 11.2 ng/mL; PAP: 857.1 +/- 364.1 ng/mL). The imbalance between coagulation and fibrinolysis described as TAT/PAP ratio was closely related with APACHE III scores in patients with sepsis (r = 0.47) and the TAT/PAP ratio in nonsurvivors was significantly higher compared with survivors (34.4 +/- 21.4 vs. 14.4 +/- 13.8).

CONCLUSION

In sepsis, both coagulation and the fibrinolysis system are activated and the imbalance between coagulation and fibrinolysis predisposes to the hypercoagulation state and is closely related to the severity of the disease and the prognosis.

Standardized measurement of major immunoglobulin class (IgG, IgA, and IgM) antibodies to beta2glycoprotein I in patients with antiphospholipid syndrome

Patients with the antiphospholipid syndrome (APS) have autoantibodies directed against epitopes on beta2 glycoprotein I (beta2GPI). We describe herein the performance characteristics of standardized enzyme-linked immunosorbent assays (ELISAs) for anti-beta2GPI of the three major immunoglobulin classes: IgG, IgA, and IgM. All three assays generated highly linear standard curves (5 points, r > or = 0.993 for each); precision was excellent both intra-assay and run-to-run, with coefficients of variation (CV) ranging from 2.3% to 6.6%. Values for IgG anti-beta2GPI correlated strongly with those obtained by an earlier method (r = 0.80, P< 0.0001). A study group consisting of 203 healthy subjects was used to generate percentile-based reference intervals for all three classes of anti-beta2GPI. APS subjects' anti-beta2GPI were found to differ significantly (P <0.0001 for each) from those of the control population. All three assays correlated well with beta2GPI-dependent anticardiolipin antibody (aCL) measurements; IgG: r = 0.94 (P <0.0001), for IgA: r = 0.82 (P<0.001) and for IgM: r = 0.84 (P<0.0001). We suggest that these ELISAs may provide valuable standardized measurements of IgG, IgA, and IgM anti-P2GPI.

Binding of anticardiolipin antibodies to protein C via beta2-glycoprotein I (beta2-GPI): a possible mechanism in the inhibitory effect of antiphospholipid antibodies on the protein C system

It is known that antiphospholipid antibodies (aPL) hamper the anticoagulant activity of the protein C system, but the mechanism is still obscure. In this study, we demonstrate that anticardiolipin antibodies (not anti-protein C autoantibodies) can bind protein C via beta2-GPI, which bears their binding epitope, in a fashion dependent on negatively charged phospholipids. We studied the binding of IgG from aPL to protein C in the presence of beta2-GPI by ELISA (anti-'protein C' antibody ELISA), and compared their binding with those obtained in the absence of beta2-GPI. In the anti-'protein C' antibody ELISA system, 47% of 78 aPL+ patients had a positive titre in the presence of cardiolipin (CL) and beta2-GPI, but binding was not found in the absence of beta2-GPI. Highly significant correlations were found between the titre of anti-'protein C' antibody in the presence of beta2-GPI and that of anti-beta2-GPI antibody (r = 0.802, P = 0.0001). We further analysed the interaction between protein C, phospholipids, beta2-GPI and human aCL MoAbs established from patients with antiphospholipid syndrome. In a first set of experiments, the binding of beta2-GPI to protein C and its phospholipid dependency were investigated. Beta2-GPI bound to protein C in the presence of CL or phosphatidylserine, but not in the presence of phosphatidylcholine or phosphatidylethanolamine. In a second group of experiments, the binding of three human monoclonal aCL recognizing the cryptic epitope of beta2-GPI (virtually anti-beta2-GPI antibodies) was evaluated in the presence of cardiolipin and beta2-GPI. All three human monoclonal aCL bound to protein C in the presence of CL and beta2-GPI, whereas they did not in the absence of either beta2-GPI or CL. These data suggest that protein C could be a target of aCL by making a complex with CL and beta2-GPI, leading to protein C dysfunction.

Mixed-backbone oligonucleotides as second generation antisense oligonucleotides: in vitro and in vivo studies

Antisense oligonucleotides are being evaluated in clinical trials as novel therapeutic agents. To further improve the properties of antisense oligonucleotides, we have designed mixed-backbone oligonucleotides (MBOs) that contain phosphorothioate segments at the 3' and 5' ends and have a modified oligodeoxynucleotide or oligoribonucleotide segment located in the central portion of the oligonucleotide. Some of these MBOs indicate improved properties compared with phosphorothioate oligodeoxynucleotides with respect to affinity to RNA, RNase H activation, and anti-HIV activity. In addition, more acceptable pharmacological, in vivo degradation and pharmacokinetic profiles were obtained with these MBOs.

Amplified Immunoassay ELISA-ELCA for Measuring Clostridium botulinum Type E Neurotoxin in Fish Fillets

The measurement of Clostridium botulinum type E toxin in fish was accomplished using an amplified immunoassay (enzyme-linked immunosorbent assay-enzyme-linked coagulation assay [ELISA-ELCA]) based on the coagulation cascade. Fresh catfish fillets inoculated with a mixture of spores from five strains of C. botulinum type E were packaged in high barrier film with air, vacuum and modified atmosphere and stored at 4, 8 or 16°C for up to 75 days. Toxin production was monitored during storage by both mouse bioassay (trypsin and non-trypsin treated) and ELISA-ELCA on the non-trypsinized samples. All 26 inoculated products that were positive by the mouse bioassay were also positive by ELISA-ELCA. Of 35 uninoculated samples which were not toxic in mouse bioassay, none were positive by ELISA-ELCA; of 73 inoculated samples which were not toxic by mouse bioassay, 14 had toxin measurable by the ELISA-ELCA. The position of these immunoassay-positives in the sampling sequence indicated that the toxin was identified by the immunoassay before it was found in the mouse bioassay. These results suggest that the ELISA-ELCA technique is a usable alternative to the mouse bioassay for monitoring C. botulinum type E toxin production in fish challenge studies.

Japan Advanced Breast Cancer Study Group and Japan Clinical Oncology Group

In order to predict a hypercoagulable state in patients with advanced breast cancer receiving medical treatment, the effects of chemoendocrine therapy on the coagulation-fibrinolytic systems were investigated prospectively. The patients were randomly divided into two groups. The ACT group had 38 patients, who received 20 mg/m2 adriamycin (ADM) i.v. on days 1 and 8, 100 mg cyclophosphamide (CPA) p.o. on days 1-14, and 20 mg tamoxifen (TAM) p.o. daily. The ACM group had 44 patients, who received 20 mg/m2 ADM i.v. on days 1 and 8, 100 mg CPA p.o. on days 1-14 and 1200 mg medroxyprogesterone acetate (MPA) p.o. daily. The treatment was repeated every 28 days until there was evidence of progressive disease or until the full ADM dose (550 mg/m2) had been given. The following 9 hematologic parameters were measured every 4 weeks: alpha 2-plasmin inhibitor plasmin complex (PIC), anti-thrombin-III (AT-III), D-dimer (Dd), fibrinogen (Fg), plasminogen (Pg), protein C (PC), thrombin-antithrombin-III complex (TAT-III), tissue plasminogen activator (t-PA), and factor X (FX). Compared to the ACT group, patients in the ACM group showed significantly higher values of AT-III and PC, which exceeded the normal ranges. The levels of Pg, t-PA and FX were significantly higher in the ACM group than in the ACT group, but were still within the normal ranges. The levels of TAT-III, Dd and PIC decreased in the ACT group and were unchanged in the ACM group after the start of treatment. Fg remained unchanged in both groups after the start of treatment. One patient in the ACM group had thrombophlebitis of the lower extremities with high levels of TAT-III, Dd and PIC and a decrease of Fg, but her condition returned to normal after reduction of the MPA dose. Although these data are not directly indicative of a hypercoagulable state in patients receiving chemoendocrine therapy, changes in AT-III, TAT-III, Dd and PIC should be monitored carefully when this type of treatment is given.

Epsilon-aminocaproic acid for treatment of fibrinolysis during liver transplantation

In 97 adult patients receiving liver transplants, the coagulation system was monitored by thrombelastography and by coagulation profile including PT; aPTT; platelet count; level of factors I, II, V, VII, VIII, IX, X, XI, and XII; fibrin degradation products; ethanol gel test; protamine gel test; and euglobulin lysis time. Preoperatively, fibrinolysis defined as a whole blood clot lysis index of less than 80% was present in 29 patients (29.9%), and a euglobulin lysis time of less than 1 h was present in 13 patients. Fibrinolysis increased progressively during surgery in 80 patients (82.5%) and was most severe on reperfusion of the graft liver in 33 patients (34%). When whole blood clot lysis (F less than 180 min) was observed during reperfusion of the graft liver, blood coagulability was tested by thrombelastography using both a blood sample treated in vitro with epsilon-aminocaproic acid (0.09%) and an untreated sample. Blood treated with epsilon-aminocaproic acid showed improved coagulation without fibrinolytic activity in all 74 tests. When whole blood clot lysis time was less than 120 min, generalized oozing occurred, and the effectiveness of epsilon-aminocaproic acid was demonstrated in vitro during the pre-anhepatic and post-anhepatic stages, epsilon-aminocaproic acid (1 g, single intravenous dose) was administered. In all 20 patients treated with epsilon-aminocaproic acid, fibrinolytic activity disappeared; whole blood clot lysis was not seen on thrombelastography during a 5-h observation period, and whole blood clot lysis index improved from 28.5 +/- 29.5% to 94.8 +/- 7.4% (mean +/- SD, P less than 0.001). None of the treated patients had hemorrhagic or thrombotic complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Liquoid-induced disseminated intravascular coagulation in the blue fox

The present experiments were performed to study the effects of a single high intravenous dose of Liquoid (10 mg/kg body weight) upon platelets, coagulation activities and hematocrit in blue foxes, and their correlation with the survival time. Both “short-living” (< 9 h) and “long-living” (24 h or more) blue foxes showed a marked consumption of coagulation factors, initial fall in fibrinogen, positive ethanol gel test and a gradual decrease in platelet counts. In addition “short-living” animals developed a marked rise in hematocrit, reflecting a considerable increase in vascular permeability. We conclude that activation of plasma proteases has as one of its effects increased permeability in microvasculatory vessels and that this may play a central role for the course and outcome of Liquoid-induced disseminated intravascular coagulation.

In vitro and in vivo correlation of clotting protease activity: effect of heparin

The thrombogenicity of three highly purified proteases (thrombin, activated Factor X, and activated Factor IX) was determined quantitatively in an animal model. The minimal amounts required to produce a standard score 4 thrombus were 1.1 nmol for thrombin, 0.12 nmol for activated Factor X, and 0.018 nmol for activated Factor IX. After the administration of heparin at 5, 10, and 20 units/kg in rabbits, the thrombogenicity of each of these proteases decreased progressively. The heparin-induced inhibition of thrombosis decreased in the order, activated Factor IX > activated Factor X > thrombin at each heparin concentration. These differences were statistically significant. These in vivo data provide support for the following hypotheses originally developed from in vitro experiments: (i) activation of the blood coagulation system, which proceeds through a cascade mechanism, incorporates biochemical amplification; (ii) the inhibition of activated Factor IX by antithrombin III in the presence of heparin is an important reaction in the prevention of thrombosis; (iii) less heparin is required to inhibit thrombosis prior to thrombin generation than afterward; (iv) an increase in the reactivity of antithrombin III reflects a decreased tendency to thrombosis while a decrease in this reactivity reflects an increased tendency to thrombosis.

The mode of action of vitamin K. Isolation of a peptide containing the vitamin K-dependent portion of prothrombin

Previous evidence has indicated that vitamin K functions in a metabolic step that specifically alters a precursor protein and converts it to biologically active prothrombin. This alteration appears to be related to the biosynthesis or attachment of a noncarbohydrate prosthetic group [Nelsestuen and Suttie (1972) J. Biol. Chem. 247, 8176]. We report the isolation of a peptide from bovine prothrombin that contains the vitamin K-dependent region of the molecule. The properties of the isolated peptide would appear to account for the major differences observed between prothrombin and its biologically inactive form produced by animals administered Dicumarol orally. These differences are quantitative absorption onto insoluble barium salts and the ability to bind calcium ions. The observed properties of this peptide provide direct evidence for the presence of a covalently bound noncarbohydrate prosthetic group(s) on the prothrombin molecule.