A Case of Acquired Hemophilia A: Usefulness of Various Methods for Judging Mixing Test Results for Monitoring the Effect of Immunosuppressive Therapy

BACKGROUND

Measurement of FVIII inhibitor (FVIII INH) levels is important for determining the effect of immunosuppressive therapy on acquired hemophilia A (AHA). However, FVIII INH can only be measured at a limited number of laboratories, which means that there are delays in obtaining the results at many sites.

METHODS

A series of mixing tests were carried out in a case of AHA, followed by comparison of various methods for judging the obtained results in association with a change of FVIII INH. The mixing test results were judged using the visual waveform pattern method and the index of circulating anticoagulant (ICA), as well as the difference between the APTT values of delayed-type and immediate-type waveforms (APTT D-I) as a numerical index.

RESULTS

All examined judgment methods reflected the change in FVIII INH, but ICA and APTT D-I were particularly sensitive for capturing this.

CONCLUSIONS

Our results suggest that a series of mixing tests are useful for rapid monitoring of the effect of immunosuppressive therapy on AHA.

Safety and Efficacy of B-domain Deleted Third Generation Recombinant Factor VIII (GreenGene F™) in Korean Patients with Hemophilia A: Data from a Post-marketing Surveillance Study

BACKGROUND

New B-domain deleted third generation recombinant factor VIII (FVIII; GreenGene F™, beroctocog alfa) was launched in 2010. We determined safety and efficacy of GreenGene F™ during routine clinical practice in patients with hemophilia A over a period of 12 months.

METHODS

From July 2010 to July 2014, a total of 136 hemophilia A patients were enrolled in a post-marketing surveillance (PMS) study. Among them, 134 patients were assessed for drug safety and 114 patients were analyzed for drug efficacy. Patients with differing hemophilia A severities and medical histories were monitored during 12 months of prophylactic and/or on-demand therapy.

RESULTS

Among 134 patients evaluated, 85 (63.4%) had severe hemophilia. Ninety-two received a total of 1,266,077 units for prophylaxis, and 42 received 516,491 units for bleeding episodes. Three patients developed inhibitors. In 112 previously treated patients, one patient (0.9%) developed inhibitor after intensive FVIII treatment for surgery. Among 22 previously untreated patients, inhibitors were observed in 2 infants (9.1%). Overall, there were a total of 47 adverse events (other than inhibitors) of all types in 30 patients (22.4%), 11 in 10 patients (7.5%) of which were considered showing serious adverse events (SAEs); most of which were hemorrhages at different sites. None of the SAEs were judged as product related. An excellent/good efficacy rate of 91.3% for hemostasis and 89.4% for hemorrhage prevention was recorded.

CONCLUSION

The results of this PMS study support the use of GreenGene F™ as safe and efficacious in hemorrhage prevention and treatment of hemophilia A. These results are consistent with the findings from previously published GreenGene F™ studies.

Severe Hemophilia and Physiologic Inhibitors of Coagulation

Patients with hemophilia demonstrate quite variable clinical phenotype even in cases with the same level of deficient factor or the same molecular abnormality. Different interacting factors including congenital and acquired alterations of coagulation inhibitors can modulate both clinical expression and severity of hemophilia. In this study, plasma levels of factor VIII (FVIII), factor IX (FIX) as well as protein C (PC), protein S (PS), and antithrombin (AT) plasma levels were measured in 80 patients with severe hemophilia A and B. Patients were divided into two groups according to the risk of bleeding: the first group (n = 32) with mild bleeding (< 2 bleeds/year), and the second group (n = 48) with severe bleeding (≥ 2 bleeds/year). Both hemophilia groups showed significantly decreased PC plasma levels compared to levels in healthy control subjects (the first group: p < 0.0001 and second group: p < 0.01). The difference in PC plasma levels between the first and second hemophilia group was significant (p < 0.05). Moreover, there was positive correlation between age and the functional PC in both hemophilia groups. Our results suggest that decreased PC plasma levels can testify to a slightly protective effect of the PC pathway on the severity and frequency of bleeding in patients with severe hemophilia A and B.

Platelet surface-associated activation and secretion-mediated inhibition of coagulation factor XII

Coagulation factor XII (fXII) is important for arterial thrombosis, but its physiological activation mechanisms are unclear. In this study, we elucidated the role of platelets and platelet-derived material in fXII activation. FXII activation was only observed upon potent platelet stimulation (with thrombin, collagen-related peptide, or calcium ionophore, but not ADP) accompanied by phosphatidylserine exposure and was localised to the platelet surface. Platelets from three patients with grey platelet syndrome did not activate fXII, which suggests that platelet-associated fXII-activating material might be released from α-granules. FXII was preferentially bound by phosphotidylserine-positive platelets and annexin V abrogated platelet-dependent fXII activation; however, artificial phosphotidylserine/phosphatidylcholine microvesicles did not support fXII activation under the conditions herein. Confocal microscopy using DAPI as a poly-phosphate marker did not reveal poly-phosphates associated with an activated platelet surface. Experimental data for fXII activation indicates an auto-inhibition mechanism (k_i/k_a = 180 molecules/platelet). Unlike surface-associated fXII activation, platelet secretion inhibited activated fXII (fXIIa), particularly due to a released C1-inhibitor. Platelet surface-associated fXIIa formation triggered contact pathway-dependent clotting in recalcified plasma. Computer modelling suggests that fXIIa inactivation was greatly decreased in thrombi under high blood flow due to inhibitor washout. Combined, the surface-associated fXII activation and its inhibition in solution herein may be regarded as a flow-sensitive regulator that can shift the balance between surface-associated clotting and plasma-dependent inhibition, which may explain the role of fXII at high shear and why fXII is important for thrombosis but negligible in haemostasis.

Impact of different inhibitor reactivities with commercial factor VIII concentrates on thrombin generation

In order to describe the haemostatic role of a variation in inhibitor reactivity with different factor VIII (FVIII) concentrates, we have compared inhibitor titres against a panel of FVIII concentrates and correlated titre with the capacity to inhibit thrombin generation. Three plasma-derived concentrates were tested in vitro in mixing experiments with inhibitor plasmas from 11 patients with severe haemophilia A: Fanhdi, which contains von Willebrand factor (VWF) with a final ratio of approximately 1:1 (VWF IU per IU FVIII:C); Haemate-P with a ratio of 2.5:1 and Hemofil-M containing only trace amounts of VWF. In addition, the recombinant FVIII concentrate Kogenate Bayer containing no VWF was included. Inhibitor titres and the capacity to generate thrombin were measured. A statistically significant difference in measured titres was found with the highest titres recorded against Hemofil-M. The inhibitor titres needed to inhibit 50% maximum thrombin generation were the lowest for Kogenate Bayer and the highest and similar for Fanhdi and Haemate-P with intermediate titres needed for inhibition of Hemofil-M. In this study, the thrombin generation assay provides additional indications for the role of VWF in the treatment of patients with inhibitors. The VWF-containing concentrates Fanhdi and Haemate-P, added to FVIII-deficient plasma with the presence of inhibitor, generate more thrombin than do the purified concentrates Hemofil-M and Kogenate Bayer.

Surgical interventions in a cohort of patients with haemophilia A and inhibitors: an experiential retrospective chart review

Strategies for the management of perioperative bleeding in patients with haemophilia and inhibitors have evolved rapidly as a result of the development of the bypassing agents Factor Eight Inhibitor Bypassing Activity, Anti-inhibitor Coagulant Complex (FEIBA) and activated recombinant factor VII (rFVIIa). However, there are currently no established guidelines for perioperative use of bypassing agents, and few controlled clinical studies have been carried out. Thus, case reports, such as those presented here, provide useful anecdotal evidence to guide the treatment of inhibitor patients. The purpose of this report was to describe experiences in the use of bypassing agents in a small cohort of patients with haemophilia A and inhibitors undergoing surgical procedures. Cases from five treatment centres were reviewed. Twenty-two procedures using FEIBA, rFVIIa or a combination of both agents were compiled from seven inhibitor patients (six with an alloantibody inhibitor and one with an acquired autoantibody inhibitor). Eleven procedures used FEIBA monotherapy, two employed rFVIIa monotherapy and nine were performed using combination therapy. Supplemental therapies were required to manage bleeding in some cases. Haemostatic control was achieved in all cases, and treatment regimens were generally well tolerated. One thrombotic adverse event was reported: evidence of disseminated intravascular coagulation (DIC) was found after rFVIIa use in one case, although the direct cause of DIC was unknown. The experiences in this case review demonstrate that both major and minor surgical procedures can be safely performed in patients with haemophilia and high-titre inhibitors under the cover of bypassing agents, with a high expectation of success.

Orthopaedic surgery for inhibitor patients: a series of 27 procedures (25 patients)

We report on a series of 27 orthopaedic surgical procedures. It includes 20 radiosynoviortheses and seven major orthopaedic procedures, performed on 26 patients. The average age of patients was 36 years (range: 8-53) and the average follow-up time was 2.5 years (range:1-5). There were 23 good results and four fair. In the synoviorthesis group (20 patients, 20 synoviortheses) the average age was 13.5 years (range: 9-26) and the average follow-up was 4.5 years (range: 1-7). There were 19 good results and one fair. All synoviortheses were done with activated prothrombin complex concentrates (FEIBA), all the responses being good except in one case (which had the final fair result). The total dose of FEIBA used was 600 IU kg(-1,) except in a patient that had a haemorrhagic complication. In fact, he required a prolongation of treatment up to a total dose of 2000 IU kg(-1). In the group of major orthopaedic procedures, the average age of the six patients was 30.5 years (range: 11-53) and the average follow-up was 2.5 years (range: 1-5). There were six good results and one fair. Postoperative bleeding complications occurred in one of the seven major orthopaedic procedures performed (arterial pseudoaneurym after a total knee arthroplasty). Despite such complication, which had the final fair result, our study has shown that haemophilic patients with high inhibitor titres requiring orthopaedic surgery can undergo such procedures with a high expectation of success. In other words, orthopaedic surgery is now possible in haemophilia patients with high-titre inhibitors, leading to an improved quality of life for these patients.

European Study on Orthopaedic Status of haemophilia patients with inhibitors

Development of inhibitors against factor VIII (FVIII) or factor IX (FIX) in haemophilia patients is one of the most serious complications of repeated exposure to replacement therapy and has major clinical and economic consequences. To evaluate the relationship between inhibitor status of haemophilia patients and their quality of life (QoL) and degree of arthropathy and to compare the orthopaedic status of patients with/without inhibitors. An observational, cross-sectional, case control study enrolling: group A (n = 38), males aged 14-35 years, with severe congenital haemophilia A or B who had inhibitors against FVIII/FIX >5 years; group B (n = 41), as group A, but aged 36-65 years and group C (n = 49), as group A, but without inhibitors. Socio-demographics: medical history, clinical characteristics and QoL were assessed. In groups A and B, 16% and 27% were hospitalized for orthopaedic procedures vs. 4% in group C. Patient mobility was also severely reduced in groups A and B, with 24% and 22% using wheelchairs vs. 4% in group C, and 50% and 51% needing a walking aid vs. 29% in group C. Significantly more joint pain was reported by patients in group A vs. those in group C; clinical/radiological orthopaedic scores were also worse in group A vs. group C. Significantly more joint abnormality was reported by patients in group A vs. group C. The burden of orthopaedic complications and the impact on QoL are more severe in haemophilia patients who have developed inhibitors than in those without inhibitors.

Early factor VIII exposure and subsequent inhibitor development in children with severe haemophilia A

Recent reports have suggested that the incidence of inhibitors in haemophilia is the highest in those first exposed to factor VIII under 6 months of age. In this study, we investigated inhibitor development in children first exposed to FVIII as neonates and also examined the effect of other genetic and environmental variables. Three hundred and forty-eight children with severe haemophilia A were investigated. Inhibitors developed in 68 of 348 (20%), with 34 of 348 (10%) high titre inhibitors. The incidence in relation to initial FVIII exposure was: <1 month nine of 35 (26%), 1-6 months 13 of 51 (25%), 6-12 months 27 of 130 (21%), 12-18 months 13 of 66 (20%) and >18 months six of 66 (9%). While we observed a significant difference in inhibitor development and age at first exposure across all age groups (P = 0.018), no significant difference was observed in children treated at different time points during the first year of life (P = 0.44). Similar results were obtained for high titre inhibitors. There was also no difference in the incidence of inhibitors in relation to initial FVIII exposure in a subgroup of 144 children with the intron 22 mutation. Inhibitors developed more frequently in those initially treated with recombinant when compared with plasma-derived FVIII (P = 0.006) and in those with a major molecular defect (P = 0.009). In this study, exposure to FVIII during the neonatal period was not associated with a higher incidence of inhibitors than those treated later during the first year of life. Initial treatment with recombinant FVIII and the presence of a major molecular defect were the most important variables affecting inhibitor development.

Long-term production of major coagulation factors and inhibitors by primary human hepatocytes in vitro: perspectives for clinical application

BACKGROUND/AIMS

Patients with coagulation factor disorders require lifelong symptomatic treatment. This is associated with limited efficacy and transmission risks. From a clinical point of view, hepatocyte transplantation offers a rational alternative but is currently being hampered by lack of functional stability of engrafted cells. It was the aim of our study to devise culture conditions providing stable cell polarity, attachment and growth factor stimulation to improve longevity and coagulation factor production.

METHODS

Human hepatocytes (HC) were plated on different extracellular matrices, inside collagen gel or Matrigel. HC were grown inside growth factor-enriched serum-free medium (SFM) or exposed to media switching from differentiation (DM) to dedifferentiation (DeDM).

RESULTS

Over more than 30 days in vitro human HC synthesized coagulation factors (factors VII, VIII, IX, fibrinogen) and coagulation inhibitors (antithrombin III, protein C). Protein synthesis was augmented when HC were grown inside a 3D collagen type I matrix, while Matrigel showed no additional benefit. Soluble growth factors improved coagulation factor production when applied in SFM or in sequential DM/DeDM. Coagulation factor levels ranged from 3% to 12% in the first week to 2.5-5% after 4 weeks, reaching biologically relevant levels.

CONCLUSION

Preserved synthesis and secretion of coagulation factors in balanced proportion by human HC in this model may offer new perspectives for HC transplantation in coagulation defects of patients.

Inflammation and the mucosal microcirculation in inflammatory bowel disease: the ebb and flow

PURPOSE OF REVIEW

Inflammatory bowel disease pathogenesis involves the interplay of multiple biological factors, among which nonimmune cells, including the endothelium, represent a crucial component of disease pathogenesis.

RECENT FINDINGS

Endothelial cells play a key role in chronic inflammation through multiple and disparate activities. The mucosal microvasculature in inflammatory bowel disease is dysfunctional, overexpresses inflammatory molecules and undergoes intense angiogenesis, failing to exert its physiological antiinflammatory and anticoagulant activities.

SUMMARY

The mucosal microcirculation is abnormal in inflammatory bowel disease and represents a novel component of disease pathogenesis; targeting the various abnormalities of the inflammatory bowel disease microcirculation may lead to new forms of therapeutic intervention.

Treatment-related risk factors of inhibitor development in previously untreated patients with hemophilia A: the CANAL cohort study

The CANAL Study (Concerted Action on Neutralizing Antibodies in severe hemophilia A) was designed to describe the relationship between treatment characteristics and inhibitor development in previously untreated patients with severe hemophilia A. This multicenter retrospective cohort study investigated 366 consecutive patients born between 1990 and 2000. The outcome was clinically relevant inhibitor development, defined as the occurrence of at least 2 positive inhibitor titers combined with a decreased recovery. Eighty-seven (24%) patients developed inhibitors (69 high titer [19%]). The incidence of inhibitors appeared to be associated with age at first treatment, decreasing from 41% for those treated within the first month of age to 18% in those treated after 18 months; after adjustment for treatment intensity, this association largely disappeared. Surgical procedures and peak treatment moments at start of treatment increased inhibitor risk (relative risk [RR], 3.7; 95% confidence interval [CI], 2.0-7.1; and RR, 3.3; CI, 2.1-5.3, respectively). Regular prophylaxis was associated with a 60% lower risk than on-demand treatment (RR, 0.4; CI, 0.2-0.8). Our findings suggest that the previously reported associated between an early age at first exposure and the risk of inhibitor development is largely explained by early, intensive treatment. The latter appears to be an independent risk factor for inhibitor development. In addition, early, regular prophylaxis may protect patients with hemophilia against the development of inhibitors.

Anti-factor Xa activity of enoxaparin administered at prophylactic dosage to patients over 75 years old

AIMS

Major bleeding complications with low-molecular-weight heparin (LMWH) treatment have been reported both in clinical studies and during postmarketing surveillance. Monitoring of antifactor Xa (anti-Xa) activities is therefore recommended in special populations often predisposed to renal impairment. The PROPHRE.75 study was conducted to estimate the distribution parameters of anti-Xa activity in the elderly.

METHODS

PROPHRE.75 was a prospective study of a cohort of consecutive patients aged >75 years and treated with 4000 IU of enoxaparin once daily for venous thromboembolism prophylaxis. Dosing history and measurements of anti-Xa activity in sparse samples were recorded throughout treatment. The covariates included weight, gender, age, renal function, medical history and concomitant medication. Population parameters and interindividual variability were estimated using NONMEM V software.

RESULTS

Anti-Xa activity was studied in 189 patients (mean age 82 +/- 5 years, 22% weighing <50 kg, 50% presenting renal impairment according to the Cockcroft and Gault formula). A first-order input two-compartment model best fitted the data. Clearance was significantly related to body weight and creatinine clearance based on the simplified Modification of Diet in Renal Disease formula, central volume being related to body weight. According to individual Bayesian estimations, 4% of patients presented with a peak anti-Xa activity >1.0 IU ml(-1), but this group did not include the sole patient experiencing a major bleed (0.53%).

CONCLUSIONS

Systematic monitoring of anti-Xa activity in elderly patients treated with enoxaparin at prophylactic doses does not seem to be necessary to prevent the occurrence of major bleeding.

Hemostasis as an optimal system

Zymogen and procofactor concentrations in physiological biochemical systems (PBS) have not yet been explained. The problem in question is to determine optimal plasma clotting factor (factors II, VII, IX, and X and cofactors V and VIII) concentrations for coagulation system (CS) as a whole. Constrained optimization technique is used to solve this problem. The constraint is determined by the ability of the CS to perform its physiological function--thrombin generation (and hence clot formation)--under vessel injury conditions. The constraint statement is based on the CS dynamics equations. In solving the problem the Lagrange multiplier is used. A hypothesis is advanced that this problem can be solved based on principle of minimum protein consumption subject to an above constraint. The results obtained indicate that the optimal clotting factor concentrations are in good agreement with those measured by biochemical techniques. A comparison between the theoretical results and experimental data lends support for our hypothesis that zymogen and procofactor concentrations in the CS (and, probably, for other biochemical systems) are determined by the principle of minimum protein consumption.

Endothelium and cardiopulmonary resuscitation

The endothelium is a viable target for injury, repair and cellular modulation. Because of its vast extension and active metabolic status of producing mediators for vasomotor tone, coagulation, and inflammation, it is a key target for therapy during ischemia/reperfusion injury. Cardiopulmonary resuscitation is a model of whole-body ischemia/reperfusion injury. It has become apparent that the endothelium participates in a host of responses elicited by ischemia/reperfusion. This review examines the role of the endothelium during and after ischemia/reperfusion and the participation by its mediators and evidence for endothelial involvement during and after cardiopulmonary resuscitation. The strategic location of the endothelium makes it an excellent signal transduction mechanism for a host of disease processes. In addition to biochemical stimuli, mechanical stimulation of the endothelium elicits production of several mediators, including endothelium-derived nitric oxide, prostaglandins, and antithrombotics and anticoagulants. Whole-body, periodic acceleration is a novel method of stimulating the endothelium via pulsatile shear stress. Periodic acceleration has been shown to be an effective experimental method of cardiopulmonary resuscitation, with evidence of postresuscitation cardioprotective effects. This review indicates that understanding endothelial modulation during and after ischemia/reperfusion will significantly improve therapeutic choices.

Importance of anticoagulant proteins in chronic liver diseases

BACKGROUND/AIMS

This study was conducted to elucidate the importance of anticoagulant proteins in chronic liver disease and their possible role as markers in determining the severity of the liver disease.

METHODS

This study was conducted on 35 patients with cirrhosis, 15 patients with chronic active hepatitis and 10 healthy controls. Coagulation inhibitor proteins such as protein C, protein S and antithrombin, as well as D-dimer level and thrombin time, which reflect fibrin degradation products, were measured. Cirrhotic patients were categorized as Child A, B and C and chronic active hepatitis patients as mild or moderate activity according to the modified Knodell histopathologic classification. The parameters were compared between patient groups and healthy controls.

RESULTS

In comparison with controls, the cirrhotics had significantly decreased protein C, protein S, antithrombin levels and increased D-dimer levels. The Child B and Child C patients differed significantly with respect to protein C and antithrombin levels only. In the chronic active hepatitis patients, protein S, protein C and fibrinogen were within normal limits, whereas antithrombin was low.

CONCLUSIONS

In chronic active hepatitis, the antithrombin level may be used as an early marker of hepatocellular damage. In cirrhotics, protein C and antithrombin may be useful for assessment of hepatocellular damage, whereas D-dimer may be important for the transition to decompensation.

Treatment of factor XI inhibitor using recombinant activated factor VIIa

A 30-year-old female with severe factor XI deficiency of 0-2% acquired factor XI inhibitor following many infusions for fresh frozen plasma (FFP) for surgical procedures starting at 4 years of age. Seven months before this inhibitor was diagnosed, surgery was complicated by prolonged bleeding resistant to FFP, requiring epsilon aminocaproic acid (EACA) and surgical packing. The inhibitor was measured at 2.2 Bethesda units, 7 months since the last FFP. The inhibitor was confirmed as specific anti-XI and anti-XIa binding by patient's IgG to immobilized factor XI and factor XIa from whole plasma and purified IgG. For repair of a painful anterior cruciate ligament (ACL) defect she was given recombinant factor VIIa (rVIIa) at 90 mug kg(-1), starting one-half hour preoperatively and continued every 2 h for 8 h when haemostasis was complete. Thereafter the rVIIa was given every 3 h for two doses, and then every 4 h for four doses at which time she was discharged on EACA which was continued for 6 days. There was excellent haemostasis during and following the surgery. There was no evidence of consumptive coagulopathy, with no change in the fibrinogen, platelet count, or D-D dimer; and no increase of platelet factor 4, beta-thromboglobulin, or prothrombin fragment F 1.2. The thrombin-antithrombin complex increased over baseline after 24 h. There was no postoperative deep vein thrombosis or pulmonary embolus. In this patient with a factor XI inhibitor, the recombinant factor VIIa was effective and safe, ensuring adequate haemostasis with no thrombotic complications. This product which was designed for patients with inhibitors to factor VIII or factor IX, and factor VII deficiency, has now been given successfully to four patients with factor XI inhibitors.

Disruption of Protein-Membrane Binding and Identification of Small-Molecule Inhibitors of Coagulation Factor VIII

Factor VIII is a critical member of the blood coagulation cascade. It binds to the membrane surfaces of activated platelets at the site of vascular injury via a highly specific interaction between factor VIII's carboxy-terminal C2 domain and their phosphatidylserine-rich lipid bilayer. We have identified small-molecule inhibitors of factor VIII's membrane binding activity that have IC50 values as low as 2.5 microM. This interaction is approximately 10(3)-fold tighter than that of free o-phospho-L-serine. These compounds also inhibit factor VIII-dependent activation of factor X, indicating that disruption of membrane lipid binding leads to inhibition of the intrinsic coagulation pathway. The tightest binding inhibitor is specific and does not prevent membrane binding by the closely related coagulation factor V. These results indicate that this and related compounds may be used as leads to develop novel antithrombotic agents.

Activated prothrombin complex concentrate (FEIBA® ) treatment during surgery in patients with inhibitors to FVIII/IX

Non-activated and activated prothrombin complex concentrates (PCC/aPCC) have been used successfully to treat bleeds in haemophilia patients with inhibitors, but most physicians do not consider these products as effective as factor VIII/IX (FVIII/IX) concentrates in non-inhibitor patients. Thus, surgical procedures in inhibitor patients have been performed reluctantly. We have performed 14 minor and five major surgical and invasive diagnostic procedures in eight patients with congenital haemophilia A and inhibitors and in two patients with acquired haemophilia. When a loading dose of 100 U kg-1 of FEIBA was given followed by 200 U kg-1 day-1 in three divided doses every 8 h for 3 days, and then, when the daily dose was tapered to 100-150 U kg-1, no severe or unexpected bleeding complications were observed. However, one adverse event was observed. A 69-year-old man who suffered a myocardial infarction the third postoperative day following sigmoidectomy was managed safely with opiate analgesia, nitrates and diuretics, and the continued use of FEIBA(R).

Binding of factor VIII inhibitors to discrete regions of the factor VIII C2 domain disrupt phospholipid binding

We characterized seven factor VIII inhibitors with epitopes in the C2 domain of factor VIII using a series of factor V C2 domain chimeras that substituted exon-sized fragments of the C2 domain of factor VIII for the corresponding regions of factor V. All inhibited co-factor activity of factor VIII and six inhibited binding of factor VIII to phosphatidylserine. Inhibitors Hz, JN and GK32 bound epitopes within amino acids S2173-K2281; inhibitors GK24 and TO bound epitopes within amino acids V2223-Y2332; and inhibitors UNC11 and UNC12 bound epitopes throughout the C2 domain (amino acids S2173-Y2332). Inhibitors Hz, JN and UNC12 inhibited the co-factor activity of chimera 5A, which substituted amino acids S2173-Q2222 of factor VIII for the corresponding region of factor V, in a prothrombinase assay. This inhibition could be partially reversed by pre-incubation of chimera 5A with phospholipid vesicles, suggesting that these antibodies interfered with phospholipid binding. Inhibitors UNC11 and UNC12, on the other hand, did not inhibit the binding of chimera 1 A to phosphatidylserine, suggesting that binding to the segment spanning amino acids V2282-Y2332 does not necessarily block phospholipid binding. These results agree with the model of the phospholipid-binding site determined by crystal structure of the C2 domain of factor VIII.

Changes of Hemostatic Variables during Hormone Replacement Therapy

Hormone replacement therapy (HRT) is accompanied by many changes in the hemostatic system. Because several individual hemostatic variables have been suspected to be reasonable indicators of the hemostatic balance and because this balance is thought to play an important role in the pathogenesis of several diseases, careful examination of the changes in this system induced by HRT could be helpful, first to improve HRT and second to improve our understanding of mechanisms of cardiovascular disease. The effects of (several forms of) HRT on individual hemostatic variables are discussed in this article. The pattern that emerges is that HRT stimulates coagulation, inhibits anticoagulation, and stimulates fibrinolysis (partly by inhibition of fibrinolysis). There are, however, few data that give clear insight into the effects of HRT on hemostatic variables. Controlled randomized clinical studies are needed to evaluate further the effects of HRT on the hemostatic system, to understand the interplay between inflammation and coagulation (both pathways being affected by HRT), and to understand how HRT-associated changes are affected by differences in genetic background.

Antibodies to factor VIIa in patients with haemophilia and high-responding inhibitors

The haemostatic effect of by-passing agents such as activated prothrombin complex concentrates (aPCC) and recombinant factor VIIa is inadequate in some patients with severe haemophilia and high-responding inhibitors. Theoretically, this could be due to antibody reactivity to procoagulant proteins other than the deficient factor. To evaluate this hypothesis, immunoglobulin (Ig) fractions from six multi-transfused patients (three haemophilia A and three haemophilia B) were purified on protein A sepharose and then subjected to immunoaffinity chromatography on factor IX sepharose and factor VIIa sepharose. All three Ig fractions from the haemophilia B patients, but not commercially available Ig, contained antibodies that bound to both gels. None of the haemophilia A patients had antibodies to factor IX but all three had antibodies towards factor VIIa. The immunoaffinity purified antifactor IX and VIIa antibodies from the haemophilia B patients inhibited thrombin formation in vitro using Feiba as active enzyme, but had no significant effect in the presence of NovoSeven. In contrast, no inhibitory effect was observed with the antifactor VIIa antibodies from the haemophilia A patients. Cross-reactivity to factor IX was seen for the antifactor VIIa antibodies from the patients with haemophilia B. Our findings show that antibody reactivity to other procoagulant factors such as factor VIIa exists in patients with high-responding inhibitors and that these antibodies may have an inhibitory potential that correlates to the amount of active enzyme present. The characterization of the antibody profile may facilitate an optimal treatment with by-passing agents in severe bleeding events.

Efficacy of recombinant factor VIIa administered by continuous infusion to haemophilia patients with inhibitors

We have prospectively monitored treatment of haemophilia patients with inhibitors by recombinant factor VIIa (rFVIIa) administered by continuous infusion to obtain more insight in the underlying factors of the clinical efficacy of this administration method. At present, 43 treatment episodes of 14 different Dutch haemophilia inhibitor patients are included in the database. Analysis of the data showed a discrepancy between the efficacy of rFVIIa continuous infusion treatment of acute and surgical bleeds in the oral cavity [one (14%) effective, two (29%) partially effective, four (57%) not effective] and other parts of the body [29 (80%) effective, four (11%) partially effective, two (6%) not effective, one (3%) impossible to classify]. Patients who had acute or surgical oral cavity bleeds, uncontrolled by rFVIIa continuous infusion, reacted favourably to rFVIIa continuous infusion in other locations of the body. Acute bleeding episodes in the oral cavity, which could not be controlled by rFVIIa continuous infusion, stopped when the treatment regimen was switched to rFVIIa bolus injections. Finally, haemostatic control during dental extractions was excellent after the initial rFVIIa bolus injection preceding the continuous infusion, but rebleeds occurred in all patients within 48 h under rFVIIa continuous infusion coverage. These observations suggest that the efficacy of rFVIIa continuous infusion depends, at least in part, on the location of the body in which the bleeding occurs and that rFVIIa bolus injections are more effective than rFVIIa continuous infusion in the oral cavity. We hypothesize that the inability of rFVIIa continuous infusion treatment to sufficiently inhibit fibrinolysis is the underlying cause of the decreased efficacy of rFVIIa continuous infusion treatment in the oral cavity.

Breastfeeding does not influence the development of inhibitors in haemophilia

Our aim was to test the hypothesis that breastfeeding may reduce development of inhibitors in male infants with haemophilia by inducing an oral immune tolerance to factor VIII. To achieve that goal, we performed a structured epidemiological survey comprising all males born with severe haemophilia A (in all 100 patients, 19 with inhibitors) or haemophilia B (in all 16 patients, six with inhibitors) in Sweden in 1980-99. Our results show no protective effect of breastfeeding.

Factors predictive of death among HIV-uninfected persons with haemophilia and other congenital coagulation disorders

Historically, the leading cause of death among persons with haemophilia and other congenital coagulation disorders was uncontrolled bleeding. Mortality was associated with severe deficiency of coagulation factors VIII or IX and especially with high-titre antifactor neutralizing antibodies (inhibitors). The catastrophic contamination of plasma donor pools with human immunodeficiency virus (HIV) resulted in acquired immunodeficiency syndrome replacing haemorrhage as the leading cause of death among persons with haemophilia. Rather little has been written, however, about mortality among those not infected with HIV. The objective of this study was to identify conditions associated with all-cause mortality among HIV-uninfected patients who were followed for a mean of 8.8 years in the Multicentre Hemophilia Cohort Study. Among the 364 children (mean age 8 years), there were four deaths; two related to cancer, one to trauma, and the fourth to haemorrhage, end-stage liver disease and sepsis. Among the 387 HIV-uninfected adults (mean age 35 years) there were 29 deaths, with haemorrhage the leading cause of death, followed by hepatic, stroke and cancer deaths. Prognostic factors for all-cause mortality among the adults included haemophilia Type A with neutralizing antibodies [age-adjusted relative rate (RR) 3.1, 95% confidence interval (CI) 1.4-6.9] and serologic evidence of both hepatitis B and C virus (RR 4.1, 95% CI 0.97-17.6). Although hepatitis C viral load was slightly lower in patients with hepatitis B virus surface antigenaemia, it was unrelated to vital status. We conclude that causes of death and prognostic factors for current HIV-uninfected haemophilia patients are similar to those noted before the HIV epidemic. Better understanding, prevention and control of neutralizing antibodies and hepatitis infections may substantially improve longevity for people with haemophilia.

A comparative double-blind randomized trial of activated protein C and unfractionated heparin in the treatment of disseminated intravascular coagulation

A randomized prospective double-blind trial was performed to compare the safety and efficacy of human activated protein C (APC) and unfractionated heparin for the treatment of disseminated intravascular coagulation (DIC). One hundred thirty-two patients with DIC were enrolled in this study: 63 patients received APC (12.5 U [2.5 microg]/kg body wt per hour) and 69 patients received heparin (8 U/kg body wt per hour) by intravenous infusion for 6 days. Forty-nine APC-treated patients and 55 heparin-treated patients were evaluated for efficacy, and 52 APC-treated patients and 55 heparin-treated patients were evaluated for safety. The 2 groups were similar with respect to sex, age, body weight, underlying diseases, and coagulation/fibrinolysis parameters before treatment. Aggravation of bleeding was seen after treatment in 8 patients receiving heparin, but in none of the patients receiving APC. The number of patients who showed alleviation of bleeding was significantly higher in the APC group than the heparin group (P = .009). The effects on DIC-related organ dysfunction were not significantly different between the 2 groups. Fibrinogen-fibrin degradation products, D-dimer, thrombin-antithrombin complex (TAT), and plasmin-plasmin inhibitor complex (PIC) were all significantly decreased by treatment in both groups. Fibrinogen, protein C, and antithrombin were significantly increased in the APC group, whereas only protein C was significantly increased in the heparin group. Platelet count in the nonleukemic group was significantly increased in those patients receiving APC but not increased in those patients receiving heparin. Improvement of coagulation/fibrinolysis was assessed by scoring 4 parameters (soluble fibrin monomers, D-dimer, TAT, and PIC), and the results indicated that the APC group showed significantly greater improvement than the heparin group (P = .046). There was, however, no significant difference in the rate of complete recovery from DIC between the 2 groups. The rate of death from any cause within 28 days after treatment was 20.4% in the APC group, significantly lower than the 40% death rate observed in the heparin group (P < .05). There were no severe adverse events in either group. These results suggest that APC in a relatively small dosage can improve DIC more efficiently than can heparin, without increasing bleeding, and may be a better alternative.

Red blood cells from patients with homozygous sickle cell disease provide a catalytic surface for factor Va inactivation by activated protein C

The structure of red blood cell (RBC) membranes in homozygous sickle cell disease (SCD) is significantly disturbed, with an increased exposure of aminophospholipids (phosphatidylserine and phosphatidylethanolamine) at the outer surface, responsible for a procoagulant activity of SS RBCs. Aminophospholipids are known not only to promote procoagulant reactions, but also to support inhibition of blood coagulation by the protein C system. The aim of the present study was to examine whether SS RBCs could serve as a catalytic surface for the inactivation of factor Va by activated protein C (APC). Venous blood was obtained from 19 consecutive SS patients and 13 controls (AA). In all SS patients, the amount of phosphatidylserine exposed at the outer surface of RBCs was increased compared with controls, as demonstrated by a prothrombinase assay. In addition, SS RBCs significantly (P < 0.0001) increased the rate of FVa inactivation by APC: the mean values (and ranges) of the factor Va inactivation rates were 30 (0-57) vs 9.5 (0-32) mmol Vai/min/mol APC for SS RBCs and normal RBCs respectively. Our results indicate that SS RBCs provide a catalytic surface for the negative control of blood coagulation, which may partially control the procoagulant activity of these cells.

Evaluation of the blood coagulation mechanism and platelet aggregation in individuals with mechanical or biological heart prostheses

Oral anticoagulants have been widely employed to decrease thrombotic risk by reducing the levels of vitamin K-dependent clotting factors. Paradoxically, the use of oral anticoagulants also decreases the levels of natural anticoagulants (protein C and protein S), which favors the hypercoagulability state. Increased platelet activation has been reported in patients undergoing warfarin treatment. These findings have raised questions about the antagonistic effect of oral anticoagulants and their implications for hemostatic balance. The aim of this study is to determine the relationship between warfarin dosage and prothrombin time [International Normalized Ratio (INR)], platelet aggregation, vitamin K-dependent clotting factors, and protein C and protein S. Blood samples from 27 patients were analyzed, seven with mechanical prostheses and 20 with biological prostheses, and 27 controls. Multiple regression analysis showed that factor II most significantly determines the INR. Results showed that the INR, clotting factors, and protein C and protein S activity did not correlate with warfarin dosage, highlighting the need for accurate laboratory monitoring of those undergoing anticoagulant therapy.

Vascular involvement in Behçet's disease: relation with thrombophilic factors, coagulation activation, and thrombomodulin

PURPOSE

Thrombosis, usually venous, occurs in 10% to 25% of patients with Behçet's disease, but its pathogenesis is poorly understood. We evaluated parameters of hemostasis and their relation with thrombosis in a series of patients with Behçet's disease.

SUBJECTS AND METHODS

We studied 38 patients with Behçet's disease (13 with venous thrombosis), 38 patients with venous thrombosis without thrombophilia, and 100 control subjects. Levels or presence of protein C, protein S, antithrombin, methylenetetrahydrofolate reductase C677T, factor V Leiden, prothrombin gene G20210A, antiphospholipid antibodies, plasminogen, tissue-type plasminogen activator (tPA), type-1 tPA inhibitor (PAI-1), PAI-1 4G/5G polymorphism, prothrombin fragment 1+2, plasmin/alpha(2)-antiplasmin complexes, thrombomodulin, and activated factors VII and XII were determined.

RESULTS

There were no deficiencies in protein C, protein S, antithrombin, or factor V Leiden in the patients with Behçet's disease, nor was there evidence of most other thrombotic abnormalities. Compared with control subjects, however, the Behçet's disease group had elevated mean (+/- SD) levels of prothrombin fragment 1+2 (2091 +/- 1323 pmol/L vs. 804 +/- 398 pmol/L, P <0.001), plasmin/alpha2-antiplasmin complexes (410 +/- 220 microg/L vs. 214 +/- 92 microg/L, P <0.001), and thrombomodulin (37 +/- 24 ng/mL vs. 27 +/- 10 ng/mL, P <0.001). These levels did not differ between patients with or without thrombosis.

CONCLUSIONS

Thrombophilic factors do not seem to explain most thromboses in Behçet's disease. There is increased thrombin generation, fibrinolysis, and thrombomodulin in Behçet's disease, but these abnormalities are not related to thrombosis.

The thrombophilic state in cancer patients

Thrombosis and disseminated intravascular coagulation are common complications of cancer. Specific conditions associated with cancer such as stasis due to immobilization or blood flow obstruction, surgery, infections, endothelium damage due to chemotherapeutic agents and abnormalities of blood coagulation contribute to the hypercoagulable and thrombophilic state of cancer patients. This procoagulant state in cancer arises mostly from the capacity of tumor cells to express and release procoagulant activities (cancer procoagulant and tissue factor). Decreased levels of inhibitors of coagulation, impaired fibrinolysis, the presence of antiphospholipid antibodies and an acquired activated protein C resistance contribute to the hypercoagulable state. The activation of coagulation is also implicated in tumor proliferation through interactions of coagulation with inflammation and increased tissue factor pathway inhibitor. Laboratory diagnosis of the thrombophilic state include (1) elevation of clotting factors, fibrinogen/fibrin degradation products, hyperfibrinogenemia and thrombocytosis and (2) elevation of specific markers of activation of coagulation: fibrinopeptide A, fragment 1 + 2, thrombin-antithrombin complexes and D-dimers. However, none of the tests has any predictive value for the occurrence of thrombotic events in one individual patient. In patients with venous thromboembolism a noninvasive screening for occult cancer is able to detect a relatively high incidence of hidden cancer and the search for thrombophilia seems important in patients without known cancer.

Coagulation inhibitors in sepsis and disseminated intravascular coagulation

Sepsis is a syndrome that is increasing in frequency and continues to be associated with an unacceptably high mortality. DIC is an important and common sequel of sepsis, is implicated in the development of multiple organ failure, and has been shown repeatedly to connote a poor prognosis. Increasing understanding of the pathogenesis of DIC has suggested several novel therapies designed to correct deficiencies in inhibitors of coagulation. To date, small randomized, controlled studies of antithrombin III concentrates in sepsis and DIC have shown a trend to increased survival, but have not achieved statistical significance. Currently, a large randomized controlled trial of antithrombin III in sepsis is being conducted. Until more data are available, important questions remain as to its proper place in the treatment of sepsis, septic shock, and DIC. Similarly, therapy with protein C and tissue factor-pathway inhibitor has been beneficial in animal models of sepsis and DIC. The results of controlled clinical trials in humans are eagerly awaited.

Combined factor V and VIII deficiency in Indian population

The clinical and haematological heterogeneity in cases of the rare combined factor V and VIII deficiency has not been reported so far from India. Nine such cases belonging to five unrelated families have been analysed in the present study for the various haematological and clinical parameters. A very mild clinical presentation is seen in all these cases. The clinical manifestations, however, do not correlate with the plasma levels of these factors.

The molecular genetics of familial venous thrombosis

In the past few years, important advances have been made in the identification of factors predisposing to familial thrombophilia. Particular attention has been paid to the characterization of known inherited defects and their genotype-phenotype relationship, and to studying the interaction between single or multiple inherited conditions and acquired risk factors for venous thrombosis. The recent discovery of 'new' and very common genetic lesions predisposing to thrombosis has greatly expanded the interest in this field. Hereditary predisposition to venous thrombosis may be related to lesions in one or more of 10-15 genes encoding antithrombin, Protein C, Protein S, Factor V, prothrombin, enzymes of the homocysteine metabolic pathway, fibrinogen, heparin cofactor II, plasminogen and thrombomodulin. About 500 different gene lesions (substitutions, deletions, insertions) have so far been reported to affect these genes in patients with thrombotic disease. Because there are potentially multiple interactions between genetic and environmental factors, familial thrombophilia is now considered to be a multifactorial disease. The aim of this chapter is to review aspects of the molecular genetics of familial thrombophilia. In particular, those gene/protein defects for which there is convincing evidence of an association with familial thrombosis will be examined in detail.

Influence of time and temperature on coagulation analytes in stored plasma

There is no comprehensive study on the stability of coagulation analytes in plasma. We therefore determined the influence of storage time and temperature on prothrombin time, activated partial thromboplastin time, thrombin time, fibrinogen, factors V and VIII, antithrombin III, protein C and S in plasma from 20 healthy subjects and 20 patients receiving heparin therapy. The stability in plasma, defined as the period during which there was a change of less than 10% from the initial value, was 8 hours for activated partial thromboplastin time, 24 hours for prothrombin time, 48 hours for factor V and 7 days for thrombin time, fibrinogen, protein C and antithrombin III in healthy subjects at 6 degrees C. Factor VIII and protein S showed 19 and 12 % reduction in activity, respectively, after 8 hours. In volunteers not treated with heparin therapy, activated partial thromboplastin time was stable for 8 hours; prothrombin time for 48 hours; and thrombin time, fibrinogen and antithrombin III for 7 days with sample storage at room temperature. Factor VIII showed a decrease of 18 % after 8 hours. For patients receiving heparin therapy, the stability of the analytes in plasma stored at 6 degrees C was 8 hours for thrombin time, 24 hours for prothrombin time and activated partial thromboplastin time and 7 days for fibrinogen and antithrombin III. Factors V and VIII showed a decrease of 13 % and 20 % respectively after 8 hours. When the plasma of these patients was stored at room temperature, factor V was stable for 8 hours, and prothrombin time for 24 hours, whereas fibrinogen and antithrombin III remained unchanged for 7 days. Activated partial thromboplastin time showed an increase of 13 %, thrombin time a fall of 16 %, and factor VIII a decrease of 18 % after 8 hours.

Late-onset warfarin-induced skin necrosis: case report and review of the literature

Warfarin-induced skin necrosis is a rare complication of therapy with warfarin or other coumarin derivatives. When it occurs it usually appears 3 to 6 days after initiation of therapy and almost always between days 1 and 10. We report a case of late-onset (16 days after initiation of therapy) warfarin-induced skin necrosis and review the literature on this rarely reported variant of warfarin-induced skin necrosis. The skin lesion in our patient was not associated with either deficiency of protein C or resistance to activated protein C.

Thrombosis in congenital deficiencies of AT III, protein C or protein S: a study of 44 children

Congenital deficiency in coagulation inhibitors is a cause of hereditary thrombotic disease. The severity of symptoms is variable and depends on the type of deficit. In this paper, 44 children suffering from deep venous thrombosis, with a mean age of 5 years, were studied. A search for Lupus anticoagulant (LA) and coagulation inhibitor deficiency showed: 3/44 cases (6.8%) had protein S deficiency, 2/44 cases (4.5%) had protein C deficiency, 1/44 cases (2.3%) had deficiencies in both protein C and S; no cases of AT III deficiency and LA was positive in 2/44 cases (4.5%). Only 1 case of APC resistance out of 13 studied was found. Four family studies were performed and confirmed the congenital origin of the disorder.

Determination of coagulation inhibitor levels and resistance to activated protein C in patients undergoing gastric surgery for benign and malignant disorders

The aim of the present study was to determine plasma levels of protein C antigen (PC:Ag) and activity (PC:Act), tissue factor pathway inhibitor (TFPI), protein S (PS), antithrombin (AT), heparin cofactor II (HCII), and resistance to activated protein C (APCR) before, during and after elective gastric surgery in order to compare patients with and without gastric malignancy. Blood was collected from a forearm vein of two age-matched patient groups undergoing elective gastric surgery, 9 patients with and 9 patients without gastric malignancy. The plasma levels of the parameters were determined preoperatively, intraoperatively, and on days 1 and 7 postoperatively. On the 1st and 7th postoperative day, plasma levels of HCII were significantly lower in patients operated for gastric malignancy than in those operated for benign disorders, but levels of TFPI, PC:Act, PC:Ag, AT, PS and APCR did not differ in the postoperative period. The day-to-day variation was also rather similar in the two patient groups.