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Moore GW, Platton S, Yartey N, Foxton E, White D, MacDonald SG. Taipan snake venom time has high sensitivity for lupus anticoagulants in non-anticoagulated, triple positive antiphospholipid syndrome patients. Int J Lab Hematol 2024; 46:538-545. [PMID: 38303489 DOI: 10.1111/ijlh.14240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 01/05/2024] [Indexed: 02/03/2024]
Abstract
INTRODUCTION Dilute Russell's viper venom time (dRVVT) and activated partial thromboplastin time (APTT) are the mainstay assays in lupus anticoagulant (LA) detection yet they have limitations, particularly in relation to interferences and specificity. The recently validated Taipan snake venom time (TSVT) screening with ecarin time (ET) confirmatory assays overcome many of those limitations due to the innate specificity engendered from direct prothrombin activation, and insensitivity to the effects of vitamin K antagonists (VKA). The present study aimed to further evidence diagnostic utility of TSVT/ET by performing them in samples from 116 nonanticoagulated patients with established triple-positive antiphospholipid syndrome (APS). METHODS Samples were identified in three expert centres who performed dRVVT, APTT and solid phase antiphospholipid antibody assays with reagents from a variety of manufacturers. All samples additionally received TSVT/ET analysis using standardised reagents. RESULTS Ninety seven of 116 (83.6%) were dRVVT- and APTT-positive, 85/97 (87.6%) of which were TSVT/ET-positive, 9/116 (7.8%) were dRVVT-positive only, 6 of which were TSVT/ET-positive, and 10/116 (8.6%) were APTT-positive only, 5 of which were TSVT/ET-positive. 96/116 TSVT/ET-positivity returned a high sensitivity for LA of 82.8%. Low coefficients of determination revealed weak relationships between LA potency and anticardiolipin and anti-β2-glycoprotein I antibody titres for all three LA assays. CONCLUSIONS TSVT/ET has high sensitivity for the clinically significant LA found in triple positive APS patients. TSVT/ET can establish multiple LA assay positivity in nonanticoagulated patients negative for one of dRVVT or APTT, and is the only assay pairing insensitive to VKAs, the recommended anticoagulation for APS.
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Affiliation(s)
- Gary W Moore
- Department of Haematology, Specialist Haemostasis Unit, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
- Department of Natural Sciences, Faculty of Science and Technology, Middlesex University, London, UK
| | - Sean Platton
- The Royal London Hospital Haemophilia Centre, Barts Health NHS Trust, London, UK
| | - Nada Yartey
- East and South East London NHS Pathology Partnership, Barts Health NHS Trust, London, UK
| | - Eleanor Foxton
- Synnovis Haemostasis and Thrombosis Laboratory, St. Thomas' Hospital, London, UK
| | - Danielle White
- Department of Haematology, Specialist Haemostasis Unit, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Stephen G MacDonald
- Department of Haematology, Specialist Haemostasis Unit, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
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Chayoua W, Nicolson PLR, Meijers JCM, Kardeby C, Garcia‐Quintanilla L, Devreese KMJ, de Laat B, Watson SP, de Groot PG. Antiprothrombin antibodies induce platelet activation: A possible explanation for anti-FXa therapy failure in patients with antiphospholipid syndrome? J Thromb Haemost 2021; 19:1776-1782. [PMID: 33774918 PMCID: PMC8360052 DOI: 10.1111/jth.15320] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 03/15/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND Arterial and venous thrombosis are both common in antiphospholipid syndrome (APS). Recent studies have shown that anti-factor Xa (FXa) therapy in APS patients leads to a greater number of patients with arterial thrombosis than with warfarin. We hypothesize that this may be due to the lowering of prothrombin levels by warfarin. OBJECTIVES To investigate whether antiprothrombin antibodies induce platelet aggregation and to identify the platelet receptors involved. A second aim was to investigate the effect of reduced prothrombin levels on antiprothrombin antibody-induced platelet aggregation. METHODS Enzyme-linked immunosorbent assays were performed to measure binding of antiprothrombin antibodies to prothrombin fragment 1+2 and prothrombin. Platelet aggregation assays in washed platelets were performed. FcγRIIA was immunoprecipitated and tyrosine-phosphorylated FcγRIIA was measured by western blot. RESULTS The antiprothrombin antibodies 28F4 and 3B1 had lupus anticoagulant (LAC) activity and caused platelet aggregation in the presence of Ca2+ and prothrombin. Antiprothrombin antibodies without LAC activity did not activate platelets. Inhibition of Syk and Src kinases and FcγRIIA blocked platelet aggregation. Fab and F(ab')2 fragments of 28F4 were unable to induce platelet aggregation. Immunoprecipitations showed that whole 28F4 immunoglobulin G induced tyrosine phosphorylation of FcγRIIA. Platelet aggregation was significantly reduced when prothrombin levels were reduced from 1 µM to 0.2 µM. CONCLUSIONS Antiprothrombin antibodies with LAC activity are able to activate platelets via FcγRIIA. Decreased prothrombin levels resulted in less antiprothrombin antibody-mediated platelet aggregation. This may explain the lower incidence of arterial thrombosis in patients treated with warfarin than with anti-FXa therapy.
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Affiliation(s)
- Walid Chayoua
- Cardiovascular Research Institute MaastrichtMaastricht University Medical CentreMaastrichtThe Netherlands
- Synapse Research InstituteMaastrichtThe Netherlands
| | - Phillip L. R. Nicolson
- Institute of Cardiovascular SciencesCollege of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
| | - Joost C. M. Meijers
- Department of Molecular and Cellular HemostasisSanquin ResearchAmsterdamThe Netherlands
- Department of Experimental Vascular MedicineAmsterdam Cardiovascular SciencesAmsterdam UMCUniversity of AmsterdamAmsterdamThe Netherlands
| | - Caroline Kardeby
- Institute of Cardiovascular SciencesCollege of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
| | - Lourdes Garcia‐Quintanilla
- Institute of Cardiovascular SciencesCollege of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
| | - Katrien M. J. Devreese
- Coagulation LaboratoryDepartment of Laboratory MedicineGhent University HospitalGhentBelgium
- Department of Diagnostic SciencesGhent UniversityGhentBelgium
| | - Bas de Laat
- Cardiovascular Research Institute MaastrichtMaastricht University Medical CentreMaastrichtThe Netherlands
- Synapse Research InstituteMaastrichtThe Netherlands
| | - Stephen P. Watson
- Institute of Cardiovascular SciencesCollege of Medical and Dental SciencesUniversity of BirminghamBirminghamUK
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Moore GW. Mixing studies for lupus anticoagulant: mostly no, sometimes yes. Clin Chem Lab Med 2021; 58:492-495. [PMID: 31874095 DOI: 10.1515/cclm-2019-1248] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 12/04/2019] [Indexed: 12/12/2022]
Abstract
Mixing tests have long been a mainstay in the lupus anticoagulant (LA) testing armoury of screen, mix and confirm assays. If a sample with an elevated screening test does not evidence inhibition in the mixing test, the search for an LA is halted and a different diagnostic pathway embarked upon. Recent years have seen studies evidencing sometimes high frequencies of false-negative mixing tests with perhaps sinister implications for missed diagnoses and skewed patient management. Issues such as the dilution effect, between-reagent sensitivity and specificity differences, variability of normal pooled plasma (NPP) quality and suitability and interpretive inconsistencies all contribute to questioning the reliability of mixing tests and their pivotal place in the LA assay hierarchy. The advent of integrated testing, where phospholipid-dependence is demonstrated or excluded prior to any attempt to evidence inhibitory properties with a fallible analytical principle, provides an alternative path to LA detection. In the absence of other causes of elevated clotting times, LA assay screen and confirm discordance is sufficient to secure a laboratory diagnosis of the presence of an LA, leaving the mixing test in a supplementary yet valuable role when further diagnostic discrimination is required.
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Affiliation(s)
- Gary W Moore
- Department of Haematology, Specialist Haemostasis Unit, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
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Moore GW. Current Controversies in Lupus Anticoagulant Detection. Antibodies (Basel) 2016; 5:E22. [PMID: 31558003 PMCID: PMC6698846 DOI: 10.3390/antib5040022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/17/2016] [Accepted: 11/18/2016] [Indexed: 01/19/2023] Open
Abstract
Antiphospholipid syndrome is an autoimmune, acquired thrombophilia diagnosed when vascular thrombosis or pregnancy morbidity are accompanied by persistent antiphospholipid antibodies. Lupus anticoagulants (LA) are one of the criteria antibodies but calibration plasmas are unavailable and they are detected by inference based on antibody behaviour in a medley of coagulation-based assays. Elevated screening tests suggest the presence of a LA, which is confirmed with mixing tests to evidence inhibition and confirmatory tests to demonstrate phospholipid-dependence. At least two screening tests of different principle must be used to account for antibody heterogeneity and controversy exists on whether assays, in addition to dilute Russell's viper venom time and activated partial thromboplastin time, should be employed. A variety of approaches to raw data manipulation and interpretation attract debate, as does inclusion or exclusion of mixing studies in circumstances where the presence of a LA is already evident from other results. Therapeutic anticoagulation compromises coagulation-based assays but careful data interpretation and use of alternative reagents can detect or exclude LA in specific circumstances, and this aspect of LA detection continues to evolve. This review focuses on the main areas of debate in LA detection.
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Affiliation(s)
- Gary W Moore
- Diagnostic Haemostasis & Thrombosis Laboratories, Department of Haemostasis and Thrombosis, Viapath Analytics, Guy's & St. Thomas' NHS Foundation Hospitals Trust, 4th floor North Wing, St. Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK.
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Abstract
The laboratory diagnosis of the antiphospholipid syndrome (APS) via antiphospholipid antibody (aPL) tests, including lupus anticoagulant (LAC), anti-cardiolipin (aCL), or anti-beta2 glycoprotein I (aβ2GPI) antibodies remains a challenge. Coagulation tests for LAC as well as solid phase assays for aCL and aβ2GPI have methodological shortcomings, although for LAC large progress have been made in standardization. All assays are associated with clinical APS-criteria (thrombotic and/or pregnancy complications) but with limited specificity. Besides, clinical studies demonstrating the association between the presence of aPL and thrombosis are not always well designed and result in wide ranges of odds ratio with large variation between studies. The best association between thrombotic complications and aPL is found for LAC. The association between thrombosis and aCL or aβ2GPI is at least inconsistent. The inclusion of more specific assays, such as the domain-I-β2GPI.antibodies is too premature and depends on further investigation in large clinical studies and the commercial availability. The search for new assays should proceed to identify patients with aPL with increased risk for thrombosis, preferable in large prospective studies. Meanwhile, with the current available LAC, aCL and aβ2GPI assays it is strongly recommended to make antibody profiles. Multiple positivity of tests seems clinically more relevant. The strengths and weaknesses of the current laboratory criteria for APS are discussed in view of their role in risk stratification of patients with thrombotic events.
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Affiliation(s)
- Katrien M J Devreese
- Coagulation Laboratory, Department of Clinical Chemistry, Ghent University Hospital, Ghent, Belgium.
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Tripodi A, Chantarangkul V, Clerici M, Palmucci C, Bison E, Banzato A, Biguzzi E, Pengo V. Standardization of lupus anticoagulant. Feasibility study of a calibration model to minimize between-method variability. Thromb Res 2011; 127:589-94. [DOI: 10.1016/j.thromres.2011.01.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 01/18/2011] [Accepted: 01/31/2011] [Indexed: 12/15/2022]
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De Laat B, Derksen RHWM, Reber G, Musial J, Swadzba J, Bozic B, Cucnik S, Regnault V, Forastiero R, Woodhams BJ, De Groot PG. An international multicentre-laboratory evaluation of a new assay to detect specifically lupus anticoagulants dependent on the presence of anti-beta2-glycoprotein autoantibodies. J Thromb Haemost 2011; 9:149-53. [PMID: 20874780 DOI: 10.1111/j.1538-7836.2010.04068.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Antiphospholipid syndrome (APS) is diagnosed by the simultaneous presence of vascular thrombosis and/or pregnancy morbidity and detection of antiphospholipid antibodies in plasma. OBJECTIVES We have shown that prolongation of clotting time by anti-beta2-glycoprotein I (beta2GPI) antibodies correlates better with thrombosis than a positive classic lupus anticoagulant (LAC) assay in a single center study. To confirm or falsify this finding we have conducted a multicenter study. METHODS AND RESULTS In 325 LAC-positive samples, we found that the beta2GPI-dependent LAC correlated 2.0 times better with thrombosis than the classic LAC assay. Although significant, this was a minimal improvement compared with the 'classic' LAC. It was published that calcium influences the behavior of anti-beta2GPI antibodies in coagulation assays. To investigate whether calcium plays a role in the present study, we divided the patient population into two groups: (i) blood was collected in 0.109 m sodium citrate and (ii) blood was drawn in 0.129 m sodium citrate as anticoagulant. We found that a positive result with the beta2GPI-dependent LAC assay correlated better with thrombosis [odds ratio (OR): 3.3, 95% confidence interval (CI) 1.9-5.8] when 0.109 m sodium citrate was used compared with 0.129 m sodium citrate (OR: 0.4, 95% CI 0.1-1.1). CONCLUSION We were able to confirm in an international multicenter study that a positive result in a beta2GPI-dependent LAC assay correlates better with thrombosis than the classic LAC assay, but that the assay needs further study as it is sensitive to external factors such as the sodium citrate concentration used as anticoagulant in the test sample.
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Affiliation(s)
- B De Laat
- Department of Clinical Chemistry and Hematology, University Medical Center, Utrecht, the Netherlands.
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Luginbühl R, Barizzi G, Sulzer I, Lämmle B, Alberio L. Screening for lupus anticoagulant: improving the performance of the lupus-sensitive PTT-LA. Int J Lab Hematol 2010; 33:168-75. [PMID: 20860735 DOI: 10.1111/j.1751-553x.2010.01262.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
INTRODUCTION The aim of the present work was to verify whether calculating a ratio between clotting times obtained with the sensitive PTT-LA and a less sensitive activated partial thromboplastin time (aPTT)-reagent may represent a valuable aPTT-based screening strategy for lupus anticoagulants (LA). METHODS For the pilot study, plasma samples from normal subjects (n = 15) and from patients with LA (n = 10), therapeutic anticoagulation with vitamin K-antagonists (VKA) (n = 15) or unfractionated heparin (n = 15), coagulation factors deficiency (n = 16), and inhibitory antibodies against factor VIII or IX (n = 11) were studied. For the evaluation study, 1553 consecutive plasma samples from nonanticoagulated patients investigated for LA between January 2005 and December 2007 at our institution were studied. Following screening strategies were employed: Pathromtin-SL (aPTT-SL), PTT-LA (aPTT-LA), ratio aPTT-LA/aPTT-SL (aPTT-ratio), and Russell's viper venom (RVV) based LA-Check. LA positive samples were identified by mixing studies and diluted RVV confirmation test (LA-Check/LA-Sure). RESULTS Pilot study: All screening strategies had a 100% sensitivity, and the aPTT-ratio reached the highest specificity (82%; 95%CI: 74-90%). Within the evaluation study, following sensitivities for LA screening were observed: aPTT-SL 59.0% (95%CI: 57-61%), aPTT-LA 82.1% (95%CI: 80-84%), aPTT-ratio 92.3% (95%CI: 91-94), and LA-Check 83.3% (95%CI: 82-85%). CONCLUSION Calculating a ratio between the LA-sensitive PTT-LA and the less sensitive Pathromtin-SL improves the performance of the PTT-LA itself and represents a simple and sensitive aPTT-based integrated strategy for LA screening.
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Affiliation(s)
- R Luginbühl
- Department of Haematology, Central Haematology Laboratory, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
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Decavele AS, Schouwers S, Devreese KMJ. Evaluation of three commercial ELISA kits for anticardiolipin and anti-beta2-glycoprotein I antibodies in the laboratory diagnosis of the antiphospholipid syndrome. Int J Lab Hematol 2010; 33:97-108. [PMID: 20813022 DOI: 10.1111/j.1751-553x.2010.01259.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
INTRODUCTION The laboratory criteria of the antiphospholipid syndrome (APS) include lupus anticoagulant (LAC), anticardiolipin antibodies (aCL) and anti-β2glycoprotein I antibodies (aβ2GPI) IgG or IgM. METHODS We evaluated three commercial ELISAs for aCL and aβ2GPI IgG and IgM: Asserachrom® ('Stago'), Bio-Rad ('BR') and the Bindazyme™ (the Binding Site, 'BS'). RESULTS Results of all assays and of LAC were correlated with the clinical background (n=228). Sensitivity for Stago/BS/BR aCL IgG was 14%/15%/18%, for aCL IgM 1%/5%/4%, for aβ2GPI IgG 9%/10%/17% and for aβ2GPI IgM 4%/4%/3%. The specificity for Stago/BS/BR for all assays ranged from 86% to 98%. The positive predictive value (PPV) for Stago/BS/BR aCL IgG was 46%/52%/40%, for aCL IgM 8%/36%/19%, for aβ2GPI IgG 70%/67%/45% and for aβ2GPI IgM 23%/23%/20%. Combining LAC with aCL and aβ2GPI antibodies increased the sensitivity (Stago/BS/BR IgG: 26%/27%/31%, IgM: 22%/21%/26%) and PPV (Stago/BS/BR IgG: 41%/46%/36%, IgM: 34%/40%/36%). Comparing the diagnostic power of the tests, only Stago/BS aβ2GPI IgG had a Chi-square P-value lower than 0.05. The combination of LAC and IgG ELISAs of BS resulted in the lowest P-value (0.098) compared to the other combinations. CONCLUSION All evaluated ELISAs are a practical tool in the laboratory diagnosis of APS. The diagnostic performance shows slight differences between the ELISAs from the different manufacturers.
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Affiliation(s)
- A S Decavele
- Coagulation Laboratory, Department of Clinical Chemistry, Microbiology and Immunology, Ghent University Hospital, De Pintelaan 185, Ghent, Belgium
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Thrombotic risk assessment in the antiphospholipid syndrome requires more than the quantification of lupus anticoagulants. Blood 2009; 115:870-8. [PMID: 19965629 DOI: 10.1182/blood-2009-09-244426] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lupus anticoagulants (LACs) are associated with thromboembolic complications (TECs). LACs can be detected by their anticoagulant properties in thrombin generation assays, by the peak height (PH) and lag time (LT). To assess the thrombotic risk in LAC-positive patients, we have expressed the LAC activity quantitatively by PH/LT calibration curves, constructed for mixtures of monoclonal antibodies against beta2-glycoprotein I (beta2GPI) and prothrombin, spiked in normal plasma. PH/LT was determined in LAC patients, with (n = 38) and without (n = 21) TECs and converted into arbitrary LAC units. LAC titers ranged from 0 to 200 AU/mL, with 5 of 59 patients being negative. In the positive LAC titer population (54 of 59), LAC and anti-beta2GPI immunoglobulin G (IgG) titers correlated with TECs, with odds ratios of 3.54 (95% CI, 1.0-1.7) and 10.0 (95% CI, 1.98-50.6), respectively. In patients with single or combined low titers, useful predictions on thrombosis could be made only after additional measurements of soluble P-selectin and factor VII. This layered strategy yielded positive and negative predictive values, sensitivity, and specificity values approximately 90% in this subgroup. Hence, LAC and anti-beta2GPI IgG titers, when combined with selected markers of the hypercoagulable state, allow a relevant thrombotic risk assessment in nearly all patients with LACs.
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Abstract
The antiphospholipid syndrome (APS) is an autoimmune disorder presenting with tissue injury in various organs attributed to large or small vessel thrombosis or, in some instances, possible nonthrombotic inflammatory mechanisms, associated with in vitro evidence of antibodies to certain proteins, or proteinphospholipid complexes. Although the pathophysiology, diagnosis, and management of APS may seem clear and straightforward from a distance, closer inspection reveals a more complex, incomplete, and uncertain image. This article reviews the evolution of APS from the first description of lupus anticoagulant to the current criteria used to guide clinical research, critiques laboratory methods used to identify autoantibodies, comments on prognosis and management, and summarizes insights into the pathophysiology of this elusive disorder.
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Affiliation(s)
- Charles Eby
- Department of Pathology and Immunology, Washington University School of Medicine, Campus box 8118, St. Louis, MO 63110, USA.
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The effects of phosphatidylserine-dependent antiprothrombin antibody on thrombin generation. ACTA ACUST UNITED AC 2009; 60:2457-67. [DOI: 10.1002/art.24708] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Devreese K, Hoylaerts MF. Laboratory diagnosis of the antiphospholipid syndrome: a plethora of obstacles to overcome. Eur J Haematol 2009; 83:1-16. [DOI: 10.1111/j.1600-0609.2009.01243.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Abstract
The presence of lupus anticoagulants (LA) in plasma alone or in combination with solid-phase antiphospholipid antibodies is an important prerequisite to define the antiphospholipid syndrome. The lack of specific tests to identify LA prompted standardization authorities to define a set of diagnostic criteria based on indirect evidence of the presence of LA and defined as screening, mixing and confirmatory studies. Accordingly, these studies must be carried out on patient plasmas and the relevant criteria satisfied before a firm diagnosis of LA can be made. Clinicians involved in LA testing should be aware of the limits which are inherent to this diagnosis, especially in patients who at the time of testing are on heparin and/or oral anticoagulant treatment, or are close to the acute thrombotic event. This article is aimed at reviewing the current situation and the light and shadows associated with this diagnostic procedure.
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Affiliation(s)
- A Tripodi
- Department of Internal Medicine, University Medical School, Mangiagalli and Regina Elena Foundation, Milano, Italy
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Moore GW, Rangarajan S, Savidge GF. The Activated Seven Lupus Anticoagulant Assay Detects Clinically Significant Antibodies. Clin Appl Thromb Hemost 2008; 14:332-7. [PMID: 17895508 DOI: 10.1177/1076029607305099] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Lupus anticoagulants are a heterogeneous group of autoantibodies detected by their effects on phospholipid-dependent coagulation assays. Persistent lupus anticoagulants are associated with thrombotic disease, but not all are clinically significant. Antibody heterogeneity and reagent and test variability dictate that at least 2 tests, of different types, should be used to screen lupus anticoagulants. The objective of this study was to investigate whether the activated seven lupus anticoagulant assay detects clinically significant antibodies. Eighty-two patients with antiphospholipid syndrome (APS) and 32 with systemic lupus erythematosus + positive for activated seven lupus anticoagulant and who were without thrombosis, who were positive by activated seven lupus anticoagulant assay, were investigated for lupus anticoagulants by dilute Russell's viper venom time, dilute activated partial thromboplastin time, and Taipan snake venom time, and for anticardiolipin antibodies. Fifty-seven of the APS patients were positive for lupus anticoagulants in multiple assays, 25 in activated seven lupus anticoagulant alone. Fourteen of the latter group were previously positive in other antiphospholipid antibodies assays, and 11 had only been positive for lupus anticoagulants by activated seven lupus anticoagulant. Twenty-eight had elevated anticardiolipin antibodies, 6 of whom were from the group that was positive in activated seven lupus anticoagulant only. Eight of the systemic lupus erythematosus + lupus anticoagulants (without thrombosis) patients were positive for lupus anticoagulant by activated seven lupus anticoagulant alone and had only been positive in activated seven lupus anticoagulant previously, and none had elevated anticardiolipin antibodies. The remaining 24 patients were lupus-anticoagulant positive in multiple assays, and 9 had elevated anticardiolipin antibodies. Dilute Russell's viper venom time and Dilute activated partial thromboplastin time are widely used to detect lupus anticoagulants and are considered to detect clinically significant antibodies. Activated seven lupus anticoagulant detected antibodies in APS patients who were positive by these assays and also lupus anticoagulants undetectable by the dilute Russell's viper venom time/dilute activated partial thromboplastin time reagents used, demonstrating its utility as a first-line or second-line assay.
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Affiliation(s)
- Gary W Moore
- Centre for Haemostasis and Thrombosis (Haemophilia Reference Centre), St Thomas' Hospital, London, England.
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Marlar RA, Husain S. The enigmas of the lupus anticoagulant: mechanisms, diagnosis, and management. Curr Rheumatol Rep 2008; 10:74-80. [PMID: 18457616 DOI: 10.1007/s11926-008-0013-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Lupus anticoagulant (LA) is a laboratory abnormality associated with the antiphospholipid syndrome. It is a paradoxical phenomenon in which one or more in vitro diagnostic clotting tests are prolonged and thus seem due to an anticoagulant, whereas the antiphospholipid syndrome is manifest clinically as inappropriate or excessive thrombosis. LA should be suspected when thrombosis, recurrent fetal loss, or a prolonged phospholipid (PL)-dependent clotting test is present without other identifiable causes. Despite the heterogeneity of LA antibodies, a consensus has evolved to identify the LA. Four conditions must be met for this laboratory diagnosis: 1) prolongation of a PL-based clotting test, 2) confirmation of an inhibitor-like pattern in the clotting test, 3) confirmation of PL dependence in coagulation tests, and 4) exclusion of a specific factor inhibitor. Even with an extensive armamentarium for LA diagnosis and treatment, it is still a formidable task.
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Affiliation(s)
- Richard A Marlar
- Laboratory Services #113, Oklahoma City Veterans Administration Medical Center, 921 Northeast 13th Street, Oklahoma City, OK 73104, USA.
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Vlachoyiannopoulos PG, Samarkos M, Sikara M, Tsiligros P. Antiphospholipid antibodies: laboratory and pathogenetic aspects. Crit Rev Clin Lab Sci 2008; 44:271-338. [PMID: 17453920 DOI: 10.1080/10408360601079549] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Antiphospholipid antibodies (aPL) constitute a heterogeneous group of autoantibodies that share the ability to bind phospholipids (PL) alone, protein-PL complexes, or PL-binding proteins. They have been detected in isolation, in association with autoimmune diseases such as systemic lupus erythematosus (SLE), and during the course of different infections. aPL have been associated with an array of clinical manifestations in virtually every organ, although deep vein and arterial thrombosis as well as pregnancy morbidity are predominant. The co-occurrence of these clinical findings with aPL constitutes the so-called antiphospholipid syndrome (APS). aPL can be detected by immunological methods [e.g., anticardiolipin antibodies (aCL)] or by functional methods that exploit the effect of aPL on blood coagulation [lupus anticoagulant (LA)]. Since aPL are heterogeneous, numerous immunological and coagulation assays have been developed. These assays have not been fully standardized, and, therefore, problems such as high interlaboratory variation are relatively frequent. Recently, recommendations have been published regarding LA and aCL testing. Not all aPL are pathogenic. However, when they are not associated with infections, they have a role in the pathogenesis of APS. Clinical and experimental data have shown that aPL exert their pathogenic activity by interfering with the function of coagulation factors, such as thrombin and factors X, XI and XII, and with the function of anticoagulant proteins of the protein C system. In addition, aPL interaction with platelets and endothelial cells induces a pro-adhesive activated phenotype.
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Abstract
BACKGROUND Lupus anticoagulants (LA) are a heterogeneous class of immunoglobulins. Persistent LA positivity is a risk factor for the occurrence and recurrence of venous/arterial thromboembolism and/or pregnancy morbidity and qualifies the patient for anticoagulation therapy. The laboratory diagnosis for LA that is used for crucial decision-making about the optimal duration of the therapy rests entirely on diagnostic criteria. These criteria are based on the prolongation of phospholipid-dependent tests not corrected upon mixing patient and normal plasmas, with confirmation provided by the evidence that the anticoagulant is directed against proteins bound to negatively charged phospholipids. AIMS This article reviews issues related to the diagnosis of LA, including the effect of preanalytical variables, choice of tests, results interpretation of screening, mixing and confirmation procedures, patients to be investigated, and transmission of results. Unresolved issues and future direction for research on laboratory diagnosis are also discussed. METHODS Search of PubMed with the key term "lupus anticoagulant" plus articles and unpublished data known to the author. RESULTS AND CONCLUSIONS The preanalytical variables (i.e., plasma preparation and storage before analysis) as well as the diagnostic steps to detect LA present potential problems that undermine the process of making a correct diagnosis. A truly specific test for LA detection is badly needed, but its development may require understanding of the mechanisms associated with the occurrence of clinical events. Until then, clinical laboratories should rely on the existing procedures, which must be applied with caution and awareness of the many issues that may affect their results.
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Affiliation(s)
- Armando Tripodi
- Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Department of Internal Medicine, University of Milan and IRCCS Maggiore Hospital, Mangiagalli and Regina Elena Foundation, Milano, Italy.
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19
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Abstract
Many investigators have been intrigued by the paradoxical association of a circulating anticoagulant, first called lupus anticoagulant by Feinstein and Rapaport [1], with a tendency to develop thrombosis, as initially described by Walter Bowie [2]. Work in Leuven on this topic started when Luis Carreras, an Argentinian hematologist, joined the laboratory of blood coagulation at this university in 1979. At that time, the head of the laboratory was Marc Verstraete. Luis had a particular interest in antibody-mediated coagulation disorders, and had prepared reviews on thrombosis and thrombocytopenia induced by heparin [3] and on the lupus inhibitor [4]. In Leuven, he joined Jos Vermylen, senior member of the laboratory, and an internist with particular interest in hemostasis, thrombosis and vascular disease. As such, Professor Vermylen was involved in both laboratory research and patient care.
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Affiliation(s)
- J Vermylen
- Centre for Molecular and Vascular Biology, University of Leuven, Herestraat 49, B 3000 Leuven, Belgium.
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Darnige L. Diagnostic biologique du syndrome des antiphospholipides. Rev Med Interne 2006; 27:296-301. [PMID: 16236386 DOI: 10.1016/j.revmed.2005.08.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2005] [Accepted: 08/16/2005] [Indexed: 11/21/2022]
Abstract
PURPOSE The antiphospholipid syndrome is a bioclinical entity defined by the occurrence of thromboses, and/or obstetrical complications in the persistent presence of antiphospholipid antibodies, i.e. lupus anticoagulant and/or anticardiolipin antibodies. This review focuses on the methods for antiphospholipid antibodies detection and their clinical usefulness. CURRENT KNOWLEDGE AND KEY POINTS Lupus anticoagulant is the strongest risk factor for thrombosis in antiphospholipid syndrome. Twenty years after its description, anticardiolipin ELISA, despite a still improvable standardization and its lack of specificity, is still required for sensitive diagnosis of antiphospholipid syndrome. FUTURE PROSPECTS AND PROJECTS A better knowledge of the beta-2-glycoprotein-I role in the pathophysiology of antiphospholipid syndrome might lead to the development of new markers of thrombotic risk.
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Affiliation(s)
- L Darnige
- Service d'Hématologie Biologique, Hôpital Européen Georges-Pompidou, 20-40, rue Leblanc, 75908 Paris cedex 15, France.
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21
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Galli M. Antiphospholipid antibodies and thrombosis: do test patterns identify the patients' risk? Thromb Res 2005; 114:597-601. [PMID: 15507297 DOI: 10.1016/j.thromres.2004.08.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2004] [Revised: 08/10/2004] [Accepted: 08/11/2004] [Indexed: 11/25/2022]
Abstract
We retrospectively analyzed the antiphospholipid profile of 103 lupus anticoagulant-positive patients to investigate whether laboratory patterns emerged for their association with arterial and venous thrombosis in the antiphospholipid syndrome. Anticardiolipin, anti-<beta>2-glycoprotein I and antiprothrombin antibodies were combined with coagulation tests in different patterns, which included from 2 to 5 laboratory variables. Overall, 22 out of 180 available associations reached significance: 14 with any type of thrombosis and eight with venous thrombosis. In all but two cases, anticardiolipin antibodies>40 units were present in the laboratory patterns that reached significance. Anti-<beta>2-glycoprotein I antibodies were present in 11 significant patterns, and antiprothrombin antibodies in seven cases. Increasing the number of variables of the laboratory patterns did not increase the odds ratio (OR) towards thrombosis. In conclusion, this analysis confirmed that the presence of IgG anticardiolipin antibodies at medium to high titres, either alone or in various combinations with other tests, is clinically useful to establish the patients' risk of thrombosis. The role of the other antiphospholipid antibodies is less clear.
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Affiliation(s)
- Monica Galli
- Divisione di Ematologia, Ospedali Riuniti, L.go Barozzi, 1, 24128 Bergamo, Italy.
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22
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Galli M. Antiphospholipid syndrome: association between laboratory tests and clinical practice. PATHOPHYSIOLOGY OF HAEMOSTASIS AND THROMBOSIS 2005; 33:249-55. [PMID: 15692225 DOI: 10.1159/000083810] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Antiphospholipid antibodies are a wide and heterogeneous group of immunoglobulins, whose presence inpatients with arterial and venous thrombosis, and obstetrical complications defines the antiphospholipid syndrome. We systematically reviewed published articles on this syndrome to investigate the association between thrombosis and the most common antiphospholipid antibodies. Lupus anticoagulants were a clear risk factor for thrombosis, irrespective of the site and type of thrombosis, the presence of systemic lupus erythematosus, and the methods used to detect them. Anticardiolipin and anti 2-glycoprotein I antibodies were possible risk factors of thrombosis, at least in some selected situations. Conversely, the measurement of antiprothrombin antibodies was not helpful to define the patient's risk of thrombosis. These results are mainly due to the still far from optimal standardization of the methods to detect the various antiphospholipid antibodies.
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Affiliation(s)
- Monica Galli
- Division of Hematology, Ospedali Riuniti, Bergamo, Italy.
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23
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Jennings I, Mackie I, Arnout J, Preston FE. Lupus anticoagulant testing using plasma spiked with monoclonal antibodies: performance in the UK NEQAS proficiency testing programme. J Thromb Haemost 2004; 2:2178-84. [PMID: 15613024 DOI: 10.1111/j.1538-7836.2004.01028.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We report here results from a United Kingdom National Quality Assessment Scheme (UK NEQAS) exercise in which both plasma spiked with monoclonal antibodies and plasma from a patient known to have lupus anticoagulant (LA) were distributed to 245 hemostasis laboratories with a request for them to test for possible LA using their routine screening procedure. In general, good agreement was seen in the diagnosis of samples spiked with monoclonal antibodies against beta2-glycoprotein 1 (beta2GP1) and prothrombin, the LA-positive patient sample, and a normal pooled plasma; over 87% of centers correctly identified each sample. However, methods employing platelet neutralizing procedures were associated with a higher proportion of false-negative responses with the antiprothrombin-spiked sample, and it is important to recognize that sensitivity and responsiveness of different methods may vary between artificial plasmas and different LA-positive patient plasmas.
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Affiliation(s)
- I Jennings
- UK NEQAS (Blood Coagulation), Sheffield, UK.
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24
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Abstract
There is increased scientific interest in the diagnosis of the antiphospholipid syndrome (APS), as therapeutic interventions can lead to substantial improvement in clinical outcome. As the clinical features of APS are far from specific, a sound laboratory method is needed to support or exclude the diagnosis. Two methods are currently used for the diagnosis of APS: (1). ELISA-based immunoassays for the detection of anticardiolipin (aCL) antibodies; and (2). clotting assays for determination of the lupus anticoagulant (LA). However, the first method is limited by a low specificity, and the second by low sensitivity. Furthermore, for both methods standardisation is unsatisfactory. Therefore, a number of new assays have been proposed as alternative or supplementary to aCL and LA tests. These include the anti-beta-2-glycoprotein I or antiprothrombin ELISAs, an ELISA utilising a phospholipid mixture, clotting assays with varying activators and assays utilising chromogenic substrates. This review presents a brief outline of APS, the autoantibodies associated with this syndrome, the basic principles of the standard assays used and a description of newer methods currently being validated.
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Affiliation(s)
- Freda Passam
- Department of Immunology, Allergy and Infectious Disease, St George Hospital, University of New South Wales, Australia
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25
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Arnout J, Vermylen J. Current status and implications of autoimmune antiphospholipid antibodies in relation to thrombotic disease. J Thromb Haemost 2003; 1:931-42. [PMID: 12871358 DOI: 10.1046/j.1538-7836.2003.00125.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This review briefly describes the development of the concepts of antiphospholipid antibody and of antiphospholipid syndrome. It focuses on the two main antigenic targets, beta2 glycoprotein I and prothrombin. An excessive production of natural antibodies rather than an immune response to exogenous antigen is proposed as pathogenetic for the development of these antibodies. The review attempts to explain how some of these antibodies are anticoagulant in vitro yet prothrombotic in vivo. The final section discusses when to test for such antibodies, how to test and how to consider treatment of patients with the antiphospholipid syndrome.
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Affiliation(s)
- J Arnout
- Center for Molecular and Vascular Biology, University of Leuven, Belgium
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26
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Affiliation(s)
- Finn Wisløff
- Department of Hematology, Hematological Research Laboratory, Ullevål University Hospital, NO-0407, Oslo, Norway.
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27
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Jennings I, Greaves M, Mackie IJ, Kitchen S, Woods TAL, Preston FE. Lupus anticoagulant testing: improvements in performance in a UK NEQAS proficiency testing exercise after dissemination of national guidelines on laboratory methods. Br J Haematol 2002; 119:364-9. [PMID: 12406070 DOI: 10.1046/j.1365-2141.2002.03821.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Laboratory screening for lupus anticoagulant (LA) has been shown to be suboptimal in several studies. Guidelines have recently been published by an expert group for the British Committee for Standards in Haematology, in an attempt to standardize and improve screening procedures. The value of using screening tests conforming with these guidelines was investigated in a United Kingdom National External Quality Assessment Scheme (UK NEQAS) proficiency testing exercise. The correct diagnosis was achieved by 97% of laboratories for a LA-negative sample. However, 18.3% of centres reported a false-negative result for a sample from a LA-positive subject. A significantly higher proportion of centres that used methods conforming with the published guidelines achieved the correct diagnosis for this sample (P < 0.002, chi-square test). A wide variety of screening tests were used by laboratories in this study. Within-method agreement could be improved by the use of a common normal pooled plasma to determine ratios. However, between-method agreement was not improved by this procedure. We conclude that adoption of methods compliant with national guidelines may improve the diagnosis of LA. There is a need, however, for reference and standardization materials to ensure further improvement in the accuracy of LA methods.
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28
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Arvieux J. Immuno-analyse et biologie spécialisée. Biologie du syndrome des antiphospholipides. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s0923-2532(02)01172-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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