Evaluation of chromogenic factor IX assays by automated protocols.

INTRODUCTION: Chromogenic substrate assays (CSA) to measure Factor IX (FIX) have recently become commercially available. However, information on their performance characteristics and use in diagnostic haemostasis laboratories remains limited. AIM: To evaluate the Hyphen Biomed (Hyphen) and Rossix FIX CSAs on fully automated coagulation analysers and compare them to the FIX one-stage assay (OSA). This study was conducted in a tertiary referral haemostasis laboratory associated with a haemophilia treatment centre. METHODS: Automated CSA protocols were adapted to the Sysmex CS2500 (CS2500) and Diagnostica Stago STA-R (STA-R) analysers. Samples assayed were from healthy volunteers, haemophilia B patients and FIX deficient plasma spiked with either plasma derived, recombinant or extended half-life FIX products. RESULTS: Reference intervals for Hyphen and Rossix assays were 73 IU/dL to 164 IU/dL and 73 IU/dL to 168 IU/dL, respectively, on the CS2500 analyser; and 84 IU/dL to 165 IU/dL for the Rossix assay on the STA-R. Repeatability across all method/analyser combinations resulted in CVs ranging from 0.8% to 5.4%. Between run reproducibility gave CVs <6.7% for all method/analyser combinations. In spiked samples, FIX recoveries were mostly within an acceptable limit of 100 ± 25% for BeneFIX® , Rixubis® and Alprolix® with some differences between CSAs. CONCLUSION: Both commercial factor FIX CSA kits can be adapted for Stago and Sysmex automated coagulation analysers. Reagent cost and workflow practices will need to be considered. These assays are potentially more consistent than OSA in measurement of replacement FIX products in haemophilia B patients.

Recombinant to modified factor VIII and factor IX - chromogenic and one-stage assays issues.

The recent development of modified recombinant factor VIII (FVIII) and factor IX (FIX) therapeutic products with extended half-lives will create challenges for the haemostasis laboratory in obtaining recovery estimates of these products in clinical samples using existing assays. The new long-acting therapeutic concentrates contain molecular modifications of Fc fusion, site-specific of polyethylene glycol or albumin fusion. The optimum methods for monitoring each new product will need to be assessed individually and laboratories should select an assay which gives similar results to the assay used to assign potency to the product in question. For some extended half-life FVIII and FIX products some one stage assays are entirely unsuitable for monitoring purposes. For most products and assay reagents studied so far, and reviewed in this manuscript, chromogenic FVIII or FIX assays can be safely used with conventional plasma standards. If one stage assays are used then they should be performed using carefully selected reagents/methods which have been shown to recover activity close to the labelled potency for the specific product being monitored.

The effects of haemodilution with hydroxyethyl starch 130/0.4 solution on coagulation as assessed by thromboelastography and platelet receptor function studies in vitro.

This study evaluated the effects of haemodilution with either 6% hydroxyethyl starch (HES) 130/0.4 (Voluven(®)) or 0.9% normal saline (NS) on blood coagulation in vitro. Haemodilution with 6% HES 130/0.4 impaired coagulation, as indicated by the changes in thromboelastographic parameters k-time, α-angle and maximum amplitude. Light transmission aggregometry and multiple electrode aggregometry demonstrated that impaired platelet receptor function occurred only at high levels of haemodilution (40%) with both fluids, but there was no significant difference between the two fluids (P=0.05). The thromboelastographic functional fibrinogen assay showed that the fibrinogen component of clot strength was significantly impaired with haemodilution with HES 130/0.4 compared with haemodilution with NS (whole blood [14.4 ± 4.6 mm] versus 40% HES dilution [3.7 ± 1.9], [P=0.001]; versus 40% NS dilution [10.4 ± 4.6], [P=0.129]). These findings suggest that there is little difference between HES or NS in relation to coagulation or platelet function during minor or moderate haemodilution, but at high levels of haemodilution with HES, fibrinogen activity is more impaired compared with NS.

The effects of haemodilution with albumin on coagulation in vitro as assessed by rotational thromboelastometry.

We investigated the in vitro viscoelastic changes of progressive haemodilution with 4% albumin compared with normal saline (NS) using rotational thromboelastometry (ROTEM(®), Pentapharm Co., Munich, Germany). Whole blood samples obtained from 20 healthy volunteers were diluted in vitro with 4% albumin or NS by 10%, 20% and 40%. Fibrinogen concentration and ROTEM(®) (EXTEM [screening test for the extrinsic haemostasis system], FIBTEM [EXTEM-based assay for the fibrin part of the clot]) variables including coagulation time, clot formation time (CFT), α-angle, maximum clot firmness and lysis index were measured in the undiluted sample and at each degree of haemodilution. There was no significant difference in fibrinogen concentration at equivalent haemodilutions with normal saline and 4% albumin solutions. Forty percent haemodilution with albumin significantly prolonged coagulation time (EXTEM P=0.007, FIBTEM P=0.0001) and significantly decreased lysis index (FIBTEM P=0.009) compared with NS. A significant decrease in maximum clot firmness from undiluted measurements (P=0.05) was observed at lower haemodilutions with albumin (20% with EXTEM, 10% with FIBTEM) compared with NS (40% with EXTEM and FIBTEM). The adverse effects of large degrees of haemodilution with 4% albumin solution are in excess of what can be explained by haemodilution alone. This study suggests that large degrees of haemodilution with albumin impair fibrinogen activity to a greater extent than equivalent degrees of haemodilution with NS.

The use of FEIBA® in the correction of coagulation abnormalities induced by dabigatran.

INTRODUCTION: Studies have shown dabigatran to be an effective anticoagulant with an acceptable bleeding profile. None the less, these patients do suffer from bleeding complications. Unfortunately, there are currently no direct reversal agents to dabigatran or established guidelines on the management of bleeding in these circumstances. METHODS: We examined the effects on thrombin generation parameters, after ex-vivo spiking the plasma of patients on dabigatran (n = 8) with FEIBA(®). These parameters were measured using the calibrated automated thrombography (CAT) machine. RESULTS: In our study, we showed the ability of FEIBA(®) to improve the abnormal thrombin generation parameters caused by dabigatran in these patients. CONCLUSION: This provides evidence, lacking in the literature, that this agent may be able to provide haemostatic support in situations where dabigatran induced coagulopathy exists.

Laboratory identification of factor VIII inhibitors in the real world: the experience from Australasia.

The laboratory has a key role in the initial detection of factor inhibitors and an ongoing role in the measurement of inhibitor titres during the course of inhibitor eradication therapy. The most commonly seen factor inhibitors are those directed against factor VIII (FVIII), usually detected either using the original or Nijmegen-modified Bethesda assay. In view of previously demonstrated high variability in laboratory results for inhibitor assays, we have more extensively examined laboratory performance in the identification of FVIII inhibitors. Over the past 3 years, we conducted two questionnaire-based surveys and two wet-challenge surveys utilizing eight samples comprising no FVIII inhibitor (n = 1), or low-titre (n = 2), medium-titre (n = 3) or high-titre (n = 2) FVIII inhibitor. Four samples were tested by 42 laboratories in 2007, and four by 52 laboratories in 2009. High inter-laboratory variation was evident, with CVs around 50% not uncommon, and some 10% of all laboratories (or around 15% of laboratories using Bethesda method) failed to detect low-level inhibitors of around 1 BU mL(-1). Laboratories using the Nijmegen method appeared to perform better than those using a standard Bethesda assay, with lower evident assay variation and no false negatives. There was a wide variety of laboratory practice, with no two laboratories using exactly the same process for testing and interpretation of factor inhibitor findings. In conclusion, our study indicates that there is still much need for standardization and improvement in factor inhibitor detection, and we hope that our findings provide a basis for future improvements in this area.

Rule based processing of the CD4000, CD3200 and CD Sapphire analyser output using the Cerner Discern Expert Module.

The latest version of our Laboratory Information System haematology laboratory expert system that handles the output of Abbott Cell-Dyn Sapphires, CD4000s and a CD3200 full blood count analyser in three high-volume haematology laboratories is described. The three hospital laboratories use Cerner Millennium Version 2007.02 software and the expert system uses Cerner Millennium Discern Expert rules and some small Cerner Command Language in-house programs. The entire expert system is totally integrated with the area-wide database and has been built and maintained by haematology staff members, as has the haematology database. Using patient demographic data, analyser numeric results, analyser error and morphology flags and previous results for the patient, this expert system decides whether to validate the main full blood count indices and white cell differential, or if the analyser results warrant further operator intervention/investigation before verifying, whether a blood film is required for microscopic review and if abnormal results require phoning to the staff treating the patient. The principles of this expert system can be generalized to different haematology analysers and haematology laboratories that have different workflows and different software.

Rituximab treatment of mild haemophilia A with inhibitors: a proposed treatment protocol.

Inhibitors are an uncommon complication of mild haemophilia A but represent a severe disease, typically with high titre inhibitors and an associated high rate of bleeding. We present data from three patients with MHAI who were successfully treated with Rituximab alone and unequivocally prove that such inhibitors respond to this agent. A treatment protocol is suggested.

Laboratory diagnosis of von Willebrand's disorder: quality and diagnostic improvements driven by peer review in a multilaboratory test process.

Regular multilaboratory surveys of laboratories derived primarily from Australia, New Zealand and Southeast Asia have been conducted over the past 7 years to evaluate testing proficiency in the diagnosis of von Willebrand's disorder (VWD) and to assess changes to test practice. Participating laboratories (currently 45) are asked to perform their usual panel of tests for VWD, and then to self-interpret test results as to the likelihood (or not) of VWD, as well as to the potential subtype identified. Samples provided in the past two survey distributions (both conducted in 2003) were as follows. Survey part A/distribution 1: Normal donor plasma, plasma with borderline normal/reduced levels of VWF (x2) and plasma from an individual with type 2 A VWD. Survey part B/distribution 2 (family VWD study): Plasma from a father, mother and son with borderline normal/reduced von Willebrand factor (VWF), and a daughter with type 3 VWD. In line with previously published survey results, the interassay and within method coefficients of variation (CV) were similar for all assays (around 15-25%), although tending to be slightly higher for VWF:RCo and VWF:CB than VWF:Ag and FVIII:C. Most laboratories reported test values consistent with expected findings, and made correct interpretations or predictions regarding the nature of the samples, although discrepant assay results or interpretations are still seen in approximately 5-10% of responses (typically from laboratories using a more limited test panel or not performing the VWF:CB). Overall, problems with the non-identification of functional VWF discordance in type 2 VWD, the misidentification of functional VWF discordance in type 1 VWD, and difficulties in discriminating types 1 and 3 VWD appear to predominate. In comparison with previous surveys, performance of electro-immuno diffusion (EID) (or Laurel gel) procedures has now ceased, and a reduction in VWF:RCo and VWF:Multimer testing and an increase in latex immunoassay (LIA) testing is sustained. We conclude that laboratories are generally proficient in tests for VWD, and that diagnostic error rates are reduced when test panels are more comprehensive and include the VWF:CB.

Laboratory diagnosis of von Willebrand disorder (vWD) and monitoring of DDAVP therapy: efficacy of the PFA-100 and vWF:CBA as combined diagnostic strategies.

We have coevaluated a combination of test processes for diagnosing von Willebrand disease (vWD) and monitoring deamino-delta-D-arginine vasopressin (DDAVP) therapy. Using normal controls (n = 23), closure time (CT) ranges measured by PFA-100(R) were (mean +/- 2SD): (i) collagen/ADP cartridge (C/ADP): 67-127 s (ii) collagen/epinephrine (C/Epi): 94-162 s. From a panel of 125 patients undergoing evaluation for clinical haemostatic defects, 29/30 samples from patients with vWD [17/18 type 1, 1/1 type 3, 3/3 type 2A, 7/7 type 2B and 1/1 pseudo-vWD] gave prolonged CTs using C/Epi. The C/ADP was less sensitive, being normal in 7/18 of the type 1 vWD individuals, with higher sensitivity to more severe vWD. Individuals with haemophilia (six factor VIII-deficient, one factor XI-deficient) gave normal CTs, while those with clinical thrombocytopenia (n=13) gave normal or prolonged CTs, somewhat dependent on platelet count. The PFA-100 was also evaluated as a part of the laboratory monitoring procedure in patients with either vWD or haemophilia undergoing a DDAVP trial as a therapeutic management process. For vWD, correction of an initially prolonged CT by DDAVP, accompanied by normalization of von Willebrand factor (vWF) measurable by von Willebrand factor antigen, vWF collagen binding activity and vWF ristocetin cofactor assays (vWF:Ag, vWF:CBA and vWF:RCof), was achieved in type 1 vWD (n=5). In an individual with type 2A vWD, DDAVP normalized vWF:Ag and vWF:RCof, but had no apparent effect on the baseline maximally prolonged CT. In an individual with type 2B vWD, factor VIII/vWF concentrate also normalized vWF:Ag and vWF:RCof, but similarly had no apparent effect on the baseline maximally prolonged CT. vWF:CBA did not normalize for either of these individuals, potentially suggesting that normalization of vWF:CBA might be required for normalization of CT. This concept is supported by correlation analysis undertaken between CT and various vWF parameters. Among these, vWF:CBA held the strongest relationship in our data set, which showed an inverse progressive rise in CT for falling vWF:CBA. Based on these results, we would conclude that the PFA-100 is highly sensitive to the presence of vWD, and may thus provide a valuable screening test for vWD. Furthermore, the combined utility of the PFA-100 and vWF:CBA as markers of DDAVP responsiveness may prove to be simple, quick but powerful, predictors for its clinical efficacy.

Retinal cholesterol emboli in the diagnosis of renal atheroembolism.

Three patients with renal failure caused by atheroembolism following cardiac vascular procedures had multiple, bilateral retinal cholesterol emboli. Ophthalmoscopy in such patients represents a noninvasive diagnostic technique that is underutilized.

Selective outgrowth of a posttransplant B-immunoblastic lymphoma expressing a latent membrane protein-1 deletion variant.

BACKGROUND: Posttransplant lymphoproliferative disorders are generally associated with Epstein-Barr virus (EBV) and are of B cell origin. We report the case of a B-immunoblastic lymphoma that developed in a pretransplantation EBV-seronegative woman 4 months after kidney transplant from her HLA-haploidentical brother. The patient successfully underwent immunotoxin therapy for lymphoma and has been in remission for 36 months. METHODS: Latent EBV genomes were identified by polymerase chain reaction, and the purified amplification products were directly sequenced with [35S]dATP. RESULTS: Molecular analysis of the latent membrane protein (LMP)1 oncogene of EBV, which was expressed in most tumor cells, revealed a 30-base pair deletion. No wild-type LMP1 sequences were found. Analysis of peripheral blood mononuclear cells from the EBV-seropositive donor showed the presence of both the LMP1 deletion variant and the wild-type sequence. The LMP1 deletion variant and the wild-type sequence were also identified within peripheral blood mononuclear cells of the EBV-seroconverted kidney recipient 20 months after lymphoma therapy. CONCLUSION: This pattern is consistent with a natural growth advantage of B cells expressing the LMP1 deletion variant in the immunocompromised host.

Deletion variants within the NF-kappa B activation domain of the LMP1 oncogene prevail in acquired immunodeficiency syndrome-related large cell lymphomas and human immunodeficiency virus-negative atypical lymphoproliferations.

This sequencing study of 17 acquired immunodeficiency syndrome-related lymphomas (9 primary brain, 8 systemic) and 8 human immunodeficiency virus-negative atypical lymphoproliferations expressing large amounts of the latent membrane protein 1 (LMP1) of Epstein-Barr virus was performed to characterize the carboxy terminal NF-kappa B activation domain of LMP1 at the molecular level in an immunocompromised host. In-frame deletions within the NF-kappa B activation domain were identified in all but 2 primary brain lymphomas, 4 systemic lymphomas, and 4 atypical lymphoproliferations, ie, in 60% of cases. In addition, non silent point mutations (range 1 to 5, mean 3.3) were detected in all cases. Although all changes occurred within the first 100 nucleotides of the carboxy terminal NF-kappa B activation domain--a critical sequence for the protein half-life--not a single point mutation was found in the remaining 62 nucleotides, necessary for malignant transformation. Such a clustering of nonrandom sequence variations, associated with a high oncoprotein expression in immunocompromised hosts, suggests that this part of the LMP1 oncogene behaves as a hypervariable region with natural selection of growth-promoting variants through prolongation of the protein half-life.

A computerized expert system for handling the output of the Technicon H1 haematology analyser.

A computer-based expert system is described which handles the output of the Technicon H1 in the haematology laboratory of a large teaching hospital. Using patient request data, analyser results, error and morphology flags, the expert system decides; whether to validate the main indices plus differential; whether a blood film is required for manual review; and which abnormal results require phoning to the requesting doctor. The results of this computer-assisted analysis are sent to a printer adjacent to the analyser. The print-out details any further action required of the operator before release of results to the main hospital computer, and serves as a log of all samples run on that analyser. Benefits of the expert system include greatly simplified interpretation of the large array of analyser flags, and consistency in sample handling for all operators over all shifts.

Application of magnetic resonance imaging to physiologic and morphologic characterization of renal artery stenosis before and after angioplasty.

This study describes the application of dynamic gadolinium-enhanced magnetic resonance (MR) imaging and MR angiography in the diagnosis and evaluation of the physiology of renal artery stenosis (RAS) before and after angioplasty. The MR imaging findings are discussed and compared to those of renal arteriography. MR time intensity curves of the renal cortex and medulla are obtained. Dynamic gadolinium-enhanced and angiographic MR data were abnormal in the setting of RAS and improved after angioplasty. The diagnosis of RAS could be made by visual inspection of MR dynamic images or MR angiographic images alone. Dynamic MR provides cross-sectional physiologic imaging data that compliments MR angiographic data. The role of dynamic gadolinium-enhanced MR in the evaluation of renovascular hypertension requires further investigation.

Evaluation of the Technicon H-1 hematology analyser.

The Technicon H-1 is a new, random-access hematology instrument performing a full blood count with leukocyte differential including eosinophils and basophils. Technical assessment showed good linearity and precision. Comparison with a Coulter S-PLUS (II) showed close correlation for all full blood count parameters except MPV and MCHC on 149 unselected hospital inpatients over a wide clinical range. No significant carry-over was detected in hemoglobin, red cell, white cell and platelet estimations. Differentials agreed closely with Technicon H6000 results for neutrophils, lymphocytes, monocytes and eosinophils. Poorer correlation with 100-cell manual differentials for all cell types except neutrophils probably reflects the relative lack of precision in manual methods. Technological innovations on the H-1 include a laser-based optical system from which several new hematological parameters are derived. The contribution they make towards improved patient care awaits assessment.