A new method measuring the interaction between von Willebrand factor and coagulation factor VIII

Introduction

There is a need for more reliable methods measuring the binding of coagulation factor VIII (FVIII) to von Willebrand factor (VWF) in plasma samples, for use in the clinical routine. We have developed such a method measuring FVIII binding in plasma, utilizing an ELISA system.

Materials and Methods

Microtiter plates were coated with a monoclonal antibody (ESH-8), reacting with the C2 domain in FVIII. Thereafter the wells were treated with recombinant FVIII (Kogenate Bayer®). After washing, diluted plasma samples were added and incubated for 1 h. Then HRP-conjugated antibodies against VWF were added and used for quantification of bound VWF.

Results

A strong signal to VWF concentration response was obtained. Plasma from patients with different types of von Willebrand disease gave frequently diminished responses. However, after correction for the VWF antigen levels, by calculation of FVIII binding/VWF antigen ratio, only the patients with known von Willebrand disease type 2 N (n = 4) had clearly abnormal results. The FVIII binding in 40 healthy individuals was determined as 1.08 ± 0.48 U/mL (SD). After correction for the VWF antigen levels the result was 0.94 ± 0.15. Thus, the SD declined substantially by this correction. The within-series CV and between-series CV were determined as 6.8 and 11.3%, respectively.

Conclusions

We have established a simple and reliable method to detect decreased binding of FVIII to von Willebrand factor in plasma samples. The method can conveniently be used to study large populations, as well as finding minor binding defects in patients.     

Sources of variation in factor VIII, von Willebrand factor and fibrinogen measurements: Implications for detecting deficiencies and increased plasma levels

Objectives

Differences in pre-analytical and assay conditions, inappropriate reference ranges, or inflammation may have the potential to impair clinical decisions based on measurements of factor VIII (FVIII), von Willebrand factor (VWF) and fibrinogen (Fg). This study examined the impact on FVIII, VWF and Fg in plasma of freezing and thawing, different citrate anticoagulant concentrations, and inflammation, as determined by high-sensitivity C-reactive protein (hsCRP).

Materials and Methods

FVIII was determined prior to freezing and after thawing using a one-stage clotting assay (FVIII:C), an amidolytic assay (FVIII:AM) and an enzyme immunoassay (FVIII:Ag). Samples were anticoagulated with 106 or 129 mmol/L of citrate. FVIII, VWF and Fg were quantified in 300 individuals to establish reference ranges and to investigate associations with hsCRP.

Results

Freezing and thawing reduced FVIII:C and FVIII:AM markedly. FVIII coagulant activities were not significantly different between samples anticoagulated with 106 or 129 mmol/L of citrate, respectively. FVIII, VWF and Fg were significantly associated with hsCRP. FVIII:C was greater than FVIII:AM and FVIII:Ag in all experiments, indicating that the presence of activated FVIII may lead to overestimation of FVIII:C.

Conclusions

Standardized freezing and thawing of plasma samples appears to be indispensable if reliable FVIII results are to be obtained. Because inflammation can potentially mask deficiency states or mimic an increased risk of thrombosis, FVIII, VWF and Fg determinations should be supplemented by measurements of hsCRP.     

Non-clinical pharmacokinetics and pharmacodynamics of rVIII-SingleChain,a novel recombinant single-chain factor VIII

Introduction

rVIII-SingleChain (CSL627), a novel recombinant coagulation factor VIII (FVIII), is under investigation in a phase I/III clinical programme (AFFINITY) for the treatment of haemophilia A. Non-clinical studies were conducted to investigate the pharmacokinetic/pharmacodynamic profile of rVIII-SingleChain in comparison with full-length recombinant FVIII.

Materials and Methods

Binding affinity of rVIII-SingleChain for von Willebrand factor was investigated by surface plasmon resonance analysis. The pharmacokinetic profile of rVIII-SingleChain was compared with a marketed full-length recombinant FVIII concentrate (Advate^®) in haemophilia A mice, von Willebrand factor knock-out mice, Crl:CD (SD) rats, rabbits and cynomolgus monkeys. Systemic FVIII activity or antigen levels were recorded. Procoagulant activity was measured in an FeCl₃-induced arterial occlusion model and by recording thrombin generation activity (ex vivo) after administration of 200–250 IU/kg rVIII-SingleChain or full-length FVIII to haemophilia A mice.

Results

rVIII-SingleChain displayed a high affinity for von Willebrand factor (K_D = 44 pM vs. 139 pM for full-length recombinant FVIII). In all animal species tested, rVIII-SingleChain had more favourable pharmacokinetic properties than full-length recombinant FVIII: clearance was decreased and area under the curve and terminal half-life were enhanced vs. full-length recombinant FVIII, while in vivo recovery and volume of distribution were equivalent. rVIII-SingleChain showed a prolonged thrombin generation potential and prolonged procoagulant activity vs. full-length recombinant FVIII in an FeCl₃-induced arterial occlusion model.

Conclusions

rVIII-SingleChain had a higher affinity for von Willebrand factor than full-length recombinant FVIII and displayed favourable pharmacokinetic/pharmacodynamic properties in non-clinical models.     

Comparison of Von Willebrand factor (VWF) activity VWF:Ac with VWF ristocetin cofactor activity VWF:RCo

Introduction

Ristocetin cofactor activity of Von Willebrand factor (VWF:RCo) and the ratio VWF:RCo to its antigen VWF:Ag are used as routine screening to estimate VWF function and to detect types of Von Willebrand disease (VWD) caused by loss of high molecular weight multimers. However, the VWF:RCo test is prone to analytic imprecisions due to various reasons. We compared an assay for VWF activity (VWF:Ac) with VWF:RCo putting emphasis on the ratios to VWF:Ag.

Materials and Methods

We evaluated 942 samples from 432 patients and evaluated three groups in detail: normal patients (normal multimers, VWF:Ag and VWF:RCo > 0.5 U/ml, VWD type 1 excluded; n = 258), VWD type 1 (n = 76) and acquired Von Willebrand syndrome (AVWS, n = 326). In addition, 30 healthy subjects were analysed.

Results

VWF:Ac and VWF:RCo correlated well (Pearson´s r = 0.96, p < 0.01), so did their ratios to VWF:Ag (Pearson´s r = 0.82, p < 0.01). We calculated the normal range of VWF:Ac/VWF:Ag for healthy subjects as 0.8-1.16. In comparison, the reference range (mean ± 2std) derived from normal patient samples was 0.73-1.14. The corresponding ranges for VWF:RCo/VWF:Ag came to 0.74-1.23 (healthy) and 0.62-1.25 (normal patients). The ratios showed similar results regarding VWD type 1. The sensitivity for AVWS was higher with VWF:Ac/VWF:Ag than with VWF:RCo/VWF:Ag (97.5% versus 84.7%).

Conclusions

The data suggest that the results obtained with the VWF:Ac assay are comparable to that of the VWF:RCo assay. An AVWS was more reliably detected by VWF:Ac/VWF:Ag. We assume that the VWF:Ac assay could replace VWF:RCo for routine screening for AVWS, especially when prompt evaluation is required.     

A two-step approach (Enzyme-linked immunosorbent assay and confirmation assay) to detect antibodies against von Willebrand factor in patients with Acquired von Willebrand Syndrome

Background

Acquired von Willebrand Syndrome is a rare bleeding disorder, which arises in individuals with no personal or family history of bleeding, associated with lymphoproliferative and myeloproliferative disorders or other diseases.

Aim

To develop a two-step approach assay to detect autoantibodies against VWF and to verify their prevalence in AVWS.

Methods

AVWS definition: negative personal or family history of bleeding diathesis, VWF below normal range and recent history of bleeding manifestations. Twenty-three consecutive patients affected by AVWS were enrolled. An ELISA assay (first step) using recombinant VWF protein immobilized on plates and sheep/goat polyclonal anti-human IgG or IgM labelled with peroxidase was developed. A group of 40 healthy subjects was tested to calculate the floating cut point value. A confirmation assay (with addition of purified VWF vs buffer) was performed (second step).

Results

Twenty–one patients (93%) had an associated disease, two patients had idiopathic AVWS. Anti-VWF autoantibodies were detected in 9 patients (39%). Of these, eight (89%) had VWF:RCo levels < 10%, but none of them resulted positive using Bethesda assay (neutralizing antibodies). The confirmation test confirmed the positive results obtained with ELISA and resulted negative in those patients with negative results and in the controls.

Conclusion

With the present two-step approach assay nine out of 23 (39%) patients affected with AVWS resulted positive for anti-VWF autoantibodies. This ELISA assay might be used as an additional confirmation tool in the diagnostic procedure in patients affected by AVWS or in the follow-up of congenital and acquired patients exposed to replacement therapy.     

Influence of factor 5 rs6025 and factor 2 rs1799963 mutation on inhibitor development in patients with hemophilia A - an Israeli-German multicenter database study

Objective

The present cohort study was performed to investigate the impact of the factor 5 rs6025 [F5] and the factor 2 rs1799963 [F2] mutations on high-titer inhibitor development [HRI] in patients with severe/moderate-severe hemophilia A [HA].

Patients and Methods

216 patients with F8 < 2% born between 1980 and 2011 were followed after initial HA diagnosis over the first 200 exposure days. The first HA patient per family who presented for diagnosis was included in the present study.

Results

32 of 216 children [14.8%] tested for F5/F2 carried either the F5 or the F2 variant. HRI occurred in 14 out of 32 F5/F2-carriers compared with 40 of 184 without F5/F2. Multivariate analysis adjusted for F8 genotype, treatment intensity, first-line use of plasma derived FVIII versus recombinant FVIII concentrates revealed that the presence of F5/F2 independently increases the risk of HRI development to odds [OR] of 3.4. Large deletions in the F8 gene [OR: 5.10], patients from Israel [OR: 4.0], the increase of FVIII per one IU/kgbw [OR: 1.05] and birth year [OR: 1.12] were significantly associated with the risk to develop HRI.

Conclusion

Data presented here suggest that HRI development is of multifactorial origin and that F5 and F2 mutations may contribute to this risk.     

Recombinant fusion protein linking factor VIIa with albumin (rVIIa­FP): Tissue distribution in rats

Introduction

A novel fusion protein linking coagulation factor VIIa with albumin (rVIIa-FP) is currently undergoing clinical investigations.

Objective

This study was conducted to examine the biodistribution of rVIIa-FP in comparison to recombinant factor VIIa (rFVIIa).

Materials and Methods

[³H]-rVIIa-FP (10 mg kg^− 1) or [³H]-rFVIIa (1.6 mg kg^− 1) were administered intravenously to rats, followed by quantitative whole-body and knee joint autoradiography for 24 ([³H]-rFVIIa) or 240 ([³H]-rVIIa-FP) hours post-dose. Pharmacokinetic and excretion balance analyses were performed.

Results

In contrast to [³H]-albumin, the tissue distributions of [³H]-rVIIa-FP and [³H]-rFVIIa were similar. Within the knee, both were rapidly present within synovial and mineralized regions. Importantly, rVIIa-FP- and albumin-derived radioactivity were detectable up to 72–120 hours, whereas [³H]-rFVIIa signals were already close to detection limits at 24 hours. The longest rVIIa-FP retention times were observed in bone marrow and endosteum, in which the retention times were up to 5 times longer for rVIIa-FP compared with rFVIIa. Up to 8 hours post-dose, 100% of radioactivity was assigned to unchanged [³H]-rVIIa-FP. Elimination of both proteins occurred primarily via the urine.

Conclusions

The data suggest that the FVIIa moiety is directing rVIIa-FP’s tissue distribution while the albumin moiety is responsible for the prolonged tissue retention. Importantly, rVIIa-FP is highly concentrated and retained over a long period in the growth plate of the knee joint − a vulnerable site in haemophilia patients. Overall, these improved tissue distribution characteristics of rVIIa-FP may enhance compliance and allow a more convenient dosing frequency.     

Serum brain-derived neurotrophic factor predicts responses to escitalopram in chronic posttraumatic stress disorder

Introduction

Some studies have found that antidepressants increase serum brain-derived neurotrophic factor (BDNF) levels in patients with major depression and the expression of BDNF mRNA in limbic structures of rats.

Objectives

This study addressed whether the SSRI escitalopram increases serum BDNF levels in subjects with PTSD and whether BDNF levels are associated with treatment response.

Methods

Medically healthy male subjects (N = 16) with chronic PTSD completed a 12 week open-label trial of flexible dose (5–20 mg/day) escitalopram monotherapy. BDNF levels were obtained at baseline, and at weeks 4, 8 and 12.

Results

PTSD symptoms significantly declined over the course of the 12 week escitalopram treatment. Despite a substantial improvement in PTSD symptoms, there was virtually no change in BDNF levels over time. Nevertheless, mean BDNF levels across the trial were strongly correlated with the slope of PTSD symptoms over the 12 weeks (r = 0.58, p = 0.018). Lower mean BDNF was associated with a greater decrease in PTSD symptoms over the course of the trial.

Conclusions

PTSD subjects with low BDNF levels demonstrated the largest treatment response from an agent with putative neurotrophic effects.     

Towards improved diagnosis of von Willebrand disease: Comparative evaluations of several automated von Willebrand factor antigen and activity assays

Introduction

von Willebrand disease (VWD) is reportedly the most common bleeding disorder and arises from deficiency and/or defects of von Willebrand factor (VWF). Laboratory diagnosis and typing has important management implications and requires a wide range of tests, including VWF activity and antigen, and involves differential identification of qualitative vs quantitative defects.

Methods

We have assessed several VWF antigen and activity assays (collagen binding [VWF:CB], ristocetin cofactor [VWF:RCo] and the new Siemens INNOVANCE assay [VWF:Ac], employing latex particles and gain of function recombinant glycoprotein Ib to facilitate VWF binding and agglutination without need for ristocetin) using different instrumentation, including the new Sysmex CS-5100, with a large sample test set (n = 600). We included retrospective plus prospective study designs, and also evaluated desmopressin responsiveness plus differential sensitivity to high molecular weight VWF.

Results

VWF:Ag and VWF:RCo results from different methods were respectively largely comparable, although some notable differences were evident, including one high false normal VWF:Ag value (105 U/dL) on a type 3 VWD sample, possibly due to heterophile antibody interference in the latex-based CS-5100 methodology. VWF:Ac was largely comparable to VWF:RCo, but VWF:CB showed discrepant findings to both VWF:RCo and VWF:Ac with some patients, most notably patients with type 2M VWD.

Conclusions

(a) VWF:Ag on different platforms are largely interchangeable, as are VWF:RCo on different platforms, except for occasional (some potentially important) differences, and manufacturer recommended methods may otherwise require some assay optimization; (b) VWF:RCo and VWF:Ac are largely interchangeable, except for occasional differences that may also relate to assay design (differing optimizations); (c) VWF:CB provides an additional activity to supplement VWF:RCo or VWF:Ac activity assays, and is not interchangeable with either.     

D-dimer,FVIII and thrombotic burden in the acute phase of deep vein thrombosis in relation to the risk of post-thrombotic syndrome

Background

Post-thrombotic syndrome (PTS) is the most common complication of deep vein thrombosis (DVT), but few data are available on the risk factors for PTS.

Aims

To assess whether the time-course of D-dimer, FVIII, and thrombotic burden are related to PTS development.

Methods

Patients (n = 59) with proximal DVT of the lower limbs (age 64; range:20-88 years; male 56%) were enrolled on the day of diagnosis (D0) and all received heparin for 5-7 days, overlapped and followed by vitamin K antagonists (VKA) for 3 months. Whole-leg compression ultrasound examination was conducted on D0 and 7 (D7), 30 (D30), and 90 (D90) days afterwards, when blood samples were also taken for D-dimer (STA Liatest) and FVIII (chromogenic assay) testing. Thrombotic burden was defined at each time point according to a score, which considered thrombosis extent and occlusion degree. Villalta score was evaluated at D30, D90, and D180.

Results

At D90, 12 patients developed PTS (Villalta score ≥ 5) and the median Villalta score was 1 (IQR 0.3-3.0) and was not correlated with either D-dimer or FVIIII time course. At D180, 13 patients had PTS and they had similar thrombotic score at D0, D30 to those without PTS, but higher at D90 (7.6 ± 5.1 vs. 3.2 ± 3.6; p = 0.011). Thrombotic score at D90 was correlated with Villalta score at D90 (rho = 0.374, p = 0.009) and at D180 (rho = 0.436, p = 0.006).

Conclusions

Thrombotic burden after 90 days of VKA is correlated with PTS.     

Persistent high factor VIII activity leading to increased thrombin generation - a prospective cohort study

Introduction

A persistently elevated level of factor VIII (FVIII) is an independent risk factor for venous thromboembolism (VTE). Although the pathophysiology of VTE is unclear, the involvement of thrombin generation (TG) has been postulated. Consequently this study was designed to (i) investigate the relationships between FVIII, Thrombin generation test (TGT) parameters and D-dimer in VTE patients, (ii) determine whether elevated levels of FVIII and increased TG in these patients are transient or sustained.

Patients and Methods

After an initial period of anticoagulation had been completed 91 VTE patients and 52 healthy controls were recruited. FVIII levels were determined by one-stage clotting (FVIII:C) and chromogenic (FVIII:Ch) assays. The potential to generate thrombin was measured using the Calibrated Automated Thrombogram (CAT) and D-Dimer was by immuno-turbidometric assay.

Results

Patients' FVIII:C levels and FVIII:Ch, exhibited good agreement (rs = 0.94; p < 0.0001), although FVIII:C exhibited a mean bias of -6%. FVIII:Ch show a significant correlation with TGT Peak Thrombin (rs = 0.30; p = 0.004) and Peak Thrombin was found to be significantly higher (p = 0.04) in patients with FVIII > 200 iu/dL. Furthermore elevated levels of FVIII and increased thrombin generation parameters appeared to be consistent over time.

Conclusion

Our data suggests that high FVIII leading to increased TG confers a significant risk of recurrent VTE and therefore we speculate that these patients may benefit from prolonged anticoagulation therapy.     

Validation of 4% albumin as a diluent in the Bethesda Assay for FVIII inhibitors

Introduction

External quality assurance programs show the Nijmegen Bethesda Assay for FVIII inhibitors improves test specificity compared to the Classic Bethesda Assay but its uptake has been slow possibly due to the cost of using FVIII deficient plasma as diluent. This study was conducted to determine if modifying the Nijmegen Bethesda assay by replacement of FVIII deficient plasma with 4% as a diluent would be suitable for for measuring FVIII inhibitors.

Materials and Methods

The titres of 59 samples from 35 patients with FVIII inhibitors were determined in parallel tests by the Nijmegen Bethesda Assay and and the modified Nijmegen assay. Method reproducibility was assessed on inhibitor-containing samples from seven individuals covering a range of titres from 1–200 Bethesda units/mL.

Results

The all-sample geometric mean titre was 6.73 Bethesda units/mL for the Nijmegen Bethesda Assay and 7.54 Bethesda units/mL for the modified Nijmegen assay. No sample was found where a difference in measured titre between methods would have altered clinical management. Agreement was very close in samples with titres less than 2 BU/mL. Both assays gave inhibitor titres in external quality assurance samples of close to consensus values. The average between-run coefficients of variation were 8.6% for the Nijmegen Bethesda Assay and 7.9% for the modified Nijmegen assay.

Conclusions

The modified Nijmegen assay using 4% albumin as the sample diluent showed good overall comparability to our existing Nijmegen Bethesda Assay and is substantially more cost-effective, making it a reasonable alternative for measuring FVIII inhibitors.     

Drug-drug interaction of the anti-TFPI aptamer BAX499 and factor VIII: Studies of spatial dynamics of fibrin clot formation in hemophilia A

Background

In recent years, a number of tissue factor pathway inhibitor (TFPI) antagonists have been developed to serve as bypassing agents to improve hemostasis in hemophilia A. Since TFPI antagonists and FVIII concentrates are procoagulants, their combined effect on spatial clot formation could be potentially pro-thrombotic.

Objective

To investigate the cooperative effect of TFPI inhibition and supplementation of FVIII in hemophilia A in a spatial, reaction-diffusion experiment in vitro.

Methods

Plasma was collected at different time points from hemophilia A patients undergoing prophylaxis and was supplemented in vitro with TFPI inhibitor BAX499 (formerly ARC19499) at concentrations from 0 up to 600 nM. Clotting propagation in recalcified plasma activated by a surface with immobilized tissue factor (TF) was monitored by videomicroscopy.

Results

Increasing concentration of BAX499 improved coagulation for all hemophilia A plasma samples activated with TF at 1.6 pmole/m² by shortening lag time and increasing initial clot growth velocity and clot size. In contrast, plasma concentration of FVIII had little effect on lag time, but increased spatial clot growth velocity. There was a decrease in the BAX499 efficiency as FVIII concentration increased (lag time shortened by 50% if FVIII:C < 5%, but the effect was only 25% if FVIII:C > 30%).

Conclusions

The results indicate that BAX499 has an effect on clotting in hemophilia A plasma at low FVIII concentrations, however has little effect at high FVIII concentrations.     

Evaluating errors in the laboratory identification of von Willebrand disease in the real world

Introduction

von Willebrand disease (VWD), reportedly the most common bleeding disorder, arises from deficiency and/or defects of von Willebrand factor (VWF). Assessment requires a wide range of tests, including VWF activity and antigen. Appropriate diagnosis including differential identification of qualitative vs quantitative defects has important management implications, but remains problematic for many laboratories and clinicians.

Methods

Data using a large set (n = 29) of varied plasma samples comprising both ‘quantitative’ VWF deficiency (‘Type 1 and 3’ VWD) vs ‘qualitative’ defects (‘Type 2 VWD’) tested in a cross-laboratory setting has been evaluated to assess the ability of real world laboratories to differentially identify these sample types.

Results

Different VWF assays and activity/antigen ratios show different utility in VWD and type identification. VWD identification errors were often linked to high inter-laboratory test variation and result misinterpretation (i.e., laboratories failed to correctly interpret their own test panel findings). Thus, moderate quantitative VWF deficient samples were misinterpreted as qualitative defects on 30/334 occasions (9% error rate); 17% of these errors were due to laboratories misinterpreting their own data, which was instead consistent with quantitative deficiencies. Conversely, whilst qualitative VWF defects were misinterpreted as quantitative deficiencies at a similar error rate (~ 9%), this was more often due to laboratories misinterpreting their data (~ 50% of errors). For test-associated errors, ristocetin cofactor was associated with the highest variability and error rate, which was at least twice that using collagen binding.

Conclusion

These findings in part explain the high rate of errors associated with VWD diagnosis.     

Vascular endothelial growth factor in the CSF of elderly patients with ventriculomegaly: Variability,periodicity and levels in drainage responders and non-responders

Objectives

The aim of this study was to examine lumbar CSF-VEGF levels from elderly patients with ventriculomegaly to evaluate the possible circadian or periodic concentration profile and relevance to the prediction of drainage response.

Methods

Lumbar CSF samples were collected in 1-h interval over 35 h from 22 patients with ventriculomegaly. CSF-VEGF levels were measured to elucidate the possible circadian or periodic concentration profiles. These VEGF levels were evaluated for correlations with clinical response to CSF drainage, ventricle size and other clinical information.

Results

The 35-h CSF-VEGF levels demonstrated a periodic concentration pattern with significant episodic fluctuation with 3–5 h intervals. CSF-VEGF levels in non-responder group in which patients did not show clinical improvement with CSF drainage were significantly higher than these in responder group.

Conclusion

VEGF variation in hydrocephalus patients suggests its possible pathophysiological role in hydrocephalus. The periodic concentration pattern of CSF-VEGF must be considered when choosing the most appropriate time for sample collection or clinical manipulation. Increased VEGF level in patients who showed no improvement with CSF drainage suggests that a possible greater ischemic or vascular injury may play a role in these patients. Pending further studies, these results suggest that high VEGF levels have a potential application in predicting non-responder patients with CSF drainage and so reducing the morbidity and cost of drainage and shunting in these patients.     

Treatment of epistaxis in hereditary hemorrhagic telangiectasia with tranexamic acid - a double-blind placebo-controlled cross-over phase IIIB study

Introduction

Epistaxis is the most frequent manifestation in hereditary hemorrhagic telangiectasia, in which no optimal treatment exists. It can lead to severe anemia and reduced quality of life. Positive effects of tranexamic acid, an antifibrinolytic drug, have been reported on epistaxis related to this disorder. We sought to evaluate the efficacy of treating nosebleeds in hereditary hemorrhagic telangiectasia with tranexamic acid.

Materials and Methods

In a randomized, double-blind, placebo controlled, cross-over phase IIIB study, 1 gram of tranexamic acid or placebo was given orally 3 times daily for 3 months for a total of 6 months.

Results

22 patients were included in the intention-to-treat analysis. Hemoglobin levels, the primary outcome measure, did not change significantly (p = 0.33). The secondary outcome measure was epistaxis score and patients reported a statistically significant reduction in nosebleeds, equaling a clinically relevant 54% diminution (p = 0.0031), as compared to the placebo period. No severe side effects were observed.

Conclusion

Tranexamic acid reduces epistaxis in patients with hereditary hemorrhagic telangiectasia.(Clinical trial registration numbers: BfArM 141 CHC 9008–001 and ClinicalTrials.gov NCT01031992)     

Changes in plasma von Willebrand factor and ADAMTS13 levels associated with left atrial remodeling in atrial fibrillation

Introduction

Previous studies have shown raised plasma von Willebrand factor (VWF) levels in patients with atrial fibrillation (AF). However, little is known about changes of VWF associated with VWF-cleaving protease (ADAMTS13) in AF. The aim of this study was to examine the relationship between changes in plasma VWF and ADAMTS13 levels, and left atrial remodeling in AF patients.

Materials and Methods

We measured plasma VWF and ADAMTS13 antigen levels in 70 paroxysmal AF (PAF) patients, 56 chronic AF (CAF) patients, and 55 control subjects.

Results

Plasma VWF levels (mU/ml) were significantly higher in CAF and PAF patients compared with the controls (2103 ± 743, 1930 ± 676, 1532 ± 555, respectively, P < 0.0001 in CAF vs. controls, P = 0.001 in PAF vs. control), while ADAMTS13 levels (mU/ml) were significantly lower in CAF and PAF patients compared with the controls (795 ± 169, 860 ± 221, 932 ± 173, respectively, P = 0.0002 in CAF vs. controls, P = 0.04 in PAF vs. control). The VWF/ADAMTS13 ratio was significantly higher in patients with CAF than PAF or controls (2.81 ± 1.30, 2.34 ± 0.92, 1.73 ± 0.83, respectively; P = 0.01 in CAF vs. PAF, P < 0.0001 in CAF vs. controls). There was a significant correlation between the VWF/ADAMTS13 ratio and left atrial diameter (positive correlation; r = 0.275, P = 0.0002) and left atrial appendage flow velocity (negative correlation; r = - 0.345, P = 0.0018).

Conclusions

These findings suggest that the imbalance between plasma VWF and ADAMTS13 levels caused by left atrial remodeling might be closely associated with intra-atrial thrombus formation in AF patients.     

Cognitive dysfunctions and cerebral microbleeds in adult patients with haemophilia A: A clinical and MRI pilot-study

Background

Studies providing information about the cognitive profile of adult haemophiliacs are lacking.

Aims

To assess the neuropsychological profile in a group of Haemophiliac patients; to detect asymptomatic cerebral microbleeds (CMBs) and any correlation between CMBs and cognitive dysfunctions; to verify how several contributing factors may determine cognitive dysfunctions and/or Magnetic Resonance Imaging (MRI) findings.

Methods

Adult haemophiliacs without history of brain bleeding were prospectively enrolled on Padua Haemophilia Centre. Patients underwent: i) “Short Neuropsychological Test” assessing cognitive functions (Short Neuropsychological Examination) to obtain an overall cognitive performance (OCP) profile standardised on a cohort matched for age, sex, cultural profile; ii) MRI of the brain to evaluate areas of brain atrophy or haemorrhagic lesions. We collected information on anti-haemorrhagic treatment, cardiovascular risk profile, viral infections, birth trauma.

Results

49 adults with haemophilia (31 severe-moderate, 18 mild) were enrolled. 73% of patients presented a reduction in OCP. According to OCP, no significant difference between severe and mild haemophilia was observed though scores tended to be worse in severe haemophilia (mean Z score 0.20 ± 0.10 vs s0.15 ± 0.11). Considering risk factors, OCP correlated significantly with coronary artery disease (p = 0.02). MRI findings in 44 patients, indicated CMBs were inversely related to OCP (R = − 0.32 p < 0.05). CMBs were associated with cardiovascular risk factors (p = 0.018).

Conclusions

Adult haemophiliacs seem to present high prevalence of mild cognitive dysfunctions that doesn’t correlate with the severity of haemophilia probably for the few number of patients evaluated. OCP impairment seems to be related to the presence of CMBs and of risk factors for cardiovascular disease.     

A shortened activated partial thromboplastin time predicts the risk of catheter-associated venous thrombosis in cancer patients

Introduction

Hypercoagulability due to high coagulation factor levels resulting from host inflammatory response to cancer contributes to an increased risk of venous thromboembolism (VTE) in cancer patients. Central venous catheters (CVCs) further heighten this risk. Activated partial thromboplastin time (aPTT) can be used to broadly screen for elevated levels of relevant coagulation factors. Our objective was to determine if a shortened aPTT ratio (coagulation time of test- to- reference plasma) was a predictor of CVC-associated VTE in cancer patients.

Materials and Methods

We performed a retrospective case–control study on cancer patients undergoing tunneled CVC insertion at our center from 1999 to 2006 and identified 40 patients who had CVC-associated VTE. VTE was confirmed with color duplex ultrasonography or computed tomography scan. For each case, we obtained 5 controls that had the same cancer diagnosis and were matched on the following factors: age, chemotherapy, hormone therapy (if applicable), tobacco use, TNM staging and year of diagnosis. All patients had aPTT testing within 30 days prior to surgery. We compared aPTT and aPTT ratio between cases and controls using Wilcoxon two sample test.

Results

aPTT ratio was significantly shorter in patients with CVC-related VTE as compared to controls [0.86 (95% confidence interval (CI) 0.78, 0.94) vs. 0.98 (0.94, 1.01), p = 0.0003]. Mean aPTT was also significantly shorter. [25.6 seconds (95% CI 23.2, 27.9) vs. 28.1 (26.9, 29.3), p = 0.001] aPTT ratios of the controls tended to spread across larger aPTT ratio values whereas those of cases tended to clustered around the mean.

Conclusions

Cancer patients undergoing catheter placement who develop CVC-associated VTE have a shorter aPTT and aPTT ratio than those who do not develop VTE. aPTT, a simple and inexpensive test might be useful as a predictor of CVC-associated VTE risk in cancer patients.     

Delirium is a risk factor for institutionalization and functional decline in older hip fracture patients

Objectives

The risk of institutionalization and functional decline is substantial after a hip fracture. However, previous research has not established the extent to which delirium plays a contributory role.

Methods

Using a prospective design, we studied 207 hip fracture patients aged 65 and older, home-dwelling before the fracture. Patients were screened daily for delirium using the Confusion Assessment Method. Proxy information on pre-fracture cognitive function and function in activities of daily living (ADL) was obtained using the Informant Questionnaire on Cognitive Decline in the Elderly, 16-item version, and the Barthel ADL Index. After 6 months, the patients' functions in ADL measured by the Barthel ADL Index and place of living were registered.

Results

Delirium was present in 80 patients (39%) during the hospital stay. After 6 months, 33 (16%) were institutionalized. Delirium and lower Barthel ADL Index score were the main risk factors for institutionalization with an adjusted odds ratio (AOR) of 5.50 (95% CI = 1.77–17.11) and 0.54 (95% CI = 0.40–0.74) respectively. In patients able to return to their private home, the independent risk factors for functional decline were higher age (B = 0.053, 95% CI = 0.003–0.102) and delirium (B = 0.768, 95% CI = 0.039–1.497).

Conclusions

At 6 month follow-up, delirium constitutes an independent risk factor for institutionalization and functional decline in hip fracture patients living at home prior to the fracture.