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Query: UMLS:C0409974 (lupus)
 22,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Six lyophilized plasma samples were sent to 20 "expert" laboratories for assessment of lupus anticoagulant (LA). Four samples contained pooled LA of graded potency mixed with aged normal plasma. One contained LA plus cephalin phospholipid and one contained a nonspecific venom anticoagulant. Sixteen methods were used overall with some participants using up to 8 methods. Results were scored in regard to the known potencies of LA in the samples and other known induced defects. Activated partial thromboplastin time (APTT) tests used by most participants for preliminary screening were relatively sensitive, but non-specific. Platelet or phospholipid neutralization procedures (PNP) appeared to be sensitive and specific but showed a non-linear response to increased LA content. Kaolin clotting time (KCT) tests showed the most sensitive response to increased LA content but the weaker LA were not scored as abnormal by most laboratories as the samples may have contained platelet fragments. Other commonly used tests such as the tissue thromboplastin inhibition (TTI) test and the dilute Russell's viper venom test (DRVVT) were carried out somewhat inconsistently. The variability in performance of tests in different laboratories indicates that standardization of methodology is urgently required. Generally it seemed that most clotting tests were "bypassed" by the addition of phospholipid to a known LA-positive sample in apparently direct proportion to their sensitivity. Sample preparation, especially prevention of contamination with activated platelets is a vital preliminary part in the assay of LA.
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PMID:Comparison of test methods for the lupus anticoagulant: international survey on lupus anticoagulants-I (ISLA-1). 212 77

The correlation between lupus anticoagulant (LA) potency and anticardiolipin antibody (ACA) ELISA was found to be poor (r = 0.40) in a group of 56 patients accumulated by a haematology department mainly for studies of LA. This correlation was similar whether LAs were assessed by kaolin clotting time or activated partial thromboplastin time increments. When the more procoagulant phospholipid phosphatidyl serine, used in a calcium-containing buffer, was substituted for cardiolipin in the ELISA, the correlation with LA was only slightly improved (r = 0.58). In fact, binding of antibody from patient plasmas to blank wells, although quantitatively reduced, was found to correlate equally well with LA activity. LAs are not necessarily phospholipid-binding antibodies but may interfere more generally with other surface-dependent processes in the clotting mechanism.
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PMID:Studies on the relationship between 'antiphospholipid' antibodies and the lupus anticoagulant. 212 89

A simplified dilute Russell's viper venom time (DRVVT) test--in which the venom, trace phospholipid and calcium were combined into a single reagent--was evaluated for the detection of lupus anticoagulants (LA) in 28 plasma samples containing non-specific circulating anticoagulants. In agreement with previous studies, the DRVVT was found to be insensitive to defects in contact and haemophilic factors and was only marginally affected by antibodies directed against factor VIII. Thus, the use of a DRVVT test in investigations of anticoagulants reduces the risk of confusing a haemorrhagic inhibitor of factor VIII with a non-haemorrhagic LA. In comparisons of sensitivity against activated partial thromboplastin time tests (APTT-Actin FSL and Organon-Teknika reagents) the simplified DRVVT was prolonged slightly more than the APTT in most of the test plasmas containing various non-specific circulating anticoagulants. Three anticoagulants affecting APTTs more than the DRVVT were found to be associated with anticardiolipin IgMs. APTT-prolonging anticoagulants, whether prolonging DRVVT tests or not, showed similar 'correction' of their APTTs by the addition of platelets or phospholipid. Thus, phospholipid-dependent or LA show heterogeneity. Those affecting only the APTT and not DRVVT should perhaps be classified differently.
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PMID:Use of a simplified dilute Russell's viper venom time (DRVVT) confirms heterogeneity among 'lupus anticoagulants'. 212 12

Platelets play a central role in haemostasis. Not only are they involved in aggregatory and agglutination responses but they are also implicated in the clotting system. The conversion of prothrombin to thrombin, in the presence of coagulation factors Va, Xa and calcium ions, is termed prothrombinase activity. For optimal expression of this process a negatively charged phospholipid surface is required. Platelets can provide such an environment, by exposing negatively charged phospholipids at their external plasma membrane, by a 'flip-flop' process whereby negatively charged phospholipids, predominantly phosphatidylserine, move from the inner plasma membrane leaflet to the outer leaflet upon the activation of platelets by certain agonists. Such agonists include collagen and thrombin and the amount of prothrombinase activity expressed is well correlated with the propensity of the agonist to activate platelet calcium-dependent protease, calpain. This enzyme is then thought to act upon platelet cytoskeletal components, thus breaking the restraining action of the cytoskeleton upon the platelet plasma membrane and facilitating 'flip-flop'. The platelet plasma membrane is therefore a dynamic surface capable of catalytic functions in coagulation systems. Recent research has high-lighted abnormalities in platelet prothrombinase expression in certain disease states. These include Bernard-Soulier syndrome, essential thrombocythaemia and conditions where the lupus anticoagulant may be present.
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PMID:Platelet prothrombinase in health and disease. 213 Sep 28

The 5-year experience with a panel of laboratory tests designed to identify patients with high risk of thromboembolism was reviewed. This panel included an activated partial thromboplastin time and reptilase time as well as specific assays for antithrombin III, protein C, protein S, and plasminogen. One hundred and nine patients were evaluated by this panel. Conditions predisposing to thrombosis were identified in 24 of these patients and these conditions included: dysfibrinogenemia, lupus anticoagulant, and deficiencies of antithrombin III, protein C and protein S. The limitations of this panel are also discussed.
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PMID:Laboratory identification of conditions predisposing to thrombosis. 214 45

Preoperative coagulation profile screening is routinely performed in otolaryngology before tonsillectomy and adenoidectomy surgery in the United States. Recently there has been controversy as to whether this routine testing is necessary. To evaluate the need for this testing, we reviewed a series of patients with particular attention to abnormal coagulation profiles. Of 91 consecutive patients undergoing tonsillectomy, adenoidectomy, or both, four had abnormal preoperative coagulation profiles. Of these patients, one had von Willebrand disease, one had hypofibrinoginemia, and two had a transient acquired lupus-like anticoagulant. The latter condition, which causes a temporary prolongation of the activated partial thromboplastin time, is discussed in detail along with a review of the pertinent literature. We conclude that coagulopathies occur frequently enough to justify preoperative screening even in the absence of a positive history.
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PMID:Abnormal coagulation profiles in tonsillectomy and adenoidectomy patients. 222 7

Anticardiolipin antibodies, immunoglobulin G, and M (IgG, IgM) have been associated with recurrent abortion and with maternal death. This study tested whether anticardiolipin titers would be a useful prenatal screening test to determine high-risk pregnancies. Titers were obtained at the first clinic visit in 686 patients, mean gestation, 20 weeks. The outcome variables were taken from a medical records computer data base. IgG anticardiolipin correlated inversely with birthweight (p less than 0.025), but not with gestation. IgM anticardiolipin correlated strongly with the inverse of patient age (p less than 0.0002) and with chronic hypertension (p less than 0.01), but not with preeclampsia. There was a weak correlation with the 1-minute Apgar score (p less than 0.05). Thirty-seven patients had titers of IgG or IgM greater than 3 standard deviations above the mean for nonpregnant patients. Sixteen of these patients were studied for antinuclear antibody and coagulopathy (prothrombin time, partial thromboplastin time, viper venom time) and all were normal. Six of eight patients tested had low range elevated antibody titers to double-stranded DNA. Ten placentas were examined and showed no infarctions. None of the correlations were of practical clinical utility. The biologic basis of the correlations found is of further interest. The value of anticardiolipin titers with lupus erythematosus, or with coagulopathy, was not tested.
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PMID:Prenatal screening for anticardiolipin antibody. 237 31

The investigators have evaluated the frequency and manifestations of anti-prothrombin antibodies in patients with the lupus anticoagulant. Thirty-one of 42 patients with lupus anticoagulants associated with a variety of underlying conditions (74%) had evidence on crossed immunoelectrophoresis of anti-prothrombin antibodies. Twenty-four of 25 patients with an activated partial thromboplastin time exceeding 50 seconds and 14 of 15 patients with a prothrombin time exceeding control by more than two seconds had demonstrable anti-prothrombin antibodies. Three of the 31 patients with anti-prothrombin antibodies had essentially no measurable plasma prothrombin, a presumed result of accelerated clearance of prothrombin/prothrombin antibody complexes. Each of these patients had bled abnormally. The remaining patients with anti-prothrombin antibodies had neither substantial hypoprothrombinemia nor hemorrhagic manifestations, which confirms the non-neutralizing property of anti-prothrombin antibodies associated with the lupus anticoagulant. Since lupus anticoagulant immunoglobulins are known to react with phospholipids, the high prevalence of antibodies binding prothrombin led us to test the hypothesis of antibody polyreactivity. Adsorption of three lupus anticoagulant plasmas with insolubilized prothrombin markedly diminished evidence of both prothrombin/prothrombin antibody complexes and anticoagulant activity. Eluates of the insolubilized prothrombin contained IgG that not only bound prothrombin but possessed lupus anticoagulant activity.
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PMID:Anti-prothrombin antibodies and the lupus anticoagulant. 245 97

The authors observed three cases (6 eyes) of vaso-occlusive retinopathy associated with the lupus anticoagulant and the related antiphospholipid antibody anticardiolipin. The disease occurred in patients who had no definable autoimmune disease such as systemic lupus erythematosus (SLE) and was characterized by severe bilateral retinal vascular occlusion. There was profound visual loss from intraretinal ischemia as well as vitreous hemorrhage from preretinal neovascularization. Results of laboratory testing showed a prolonged partial thromboplastin time (PTT) in two patients, and the presence of the lupus anticoagulant in all. Treatment with panretinal photocoagulation appeared to stabilize the neovascularization. The role of systemic anticoagulation and immunosuppressive therapy is uncertain.
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PMID:Vaso-occlusive retinopathy associated with antiphospholipid antibodies (lupus anticoagulant retinopathy). 232

With the well-documented association of lupus anticoagulants with thrombotic disease and recurrent spontaneous abortion, the laboratory approach to diagnosing these inhibitors is more critical now. To this end, we examined plasma samples from 21 patients who initially presented with a prolonged prothrombin time or activated partial thromboplastin time or both for the presence of lupus anticoagulants. We used a battery of coagulation tests, including both immediate and two-hour mixing studies, a platelet neutralization procedure, a tissue thromboplastin inhibition test, and dilute Russell viper venom times. Two patients (10%) had only a prolonged prothrombin time, seven (33%) had only a prolonged activated partial thromboplastin time, and in 12 (57%) both were abnormal. In 15 patients, inhibition was evident on immediate assay of equal-volume mixture studies of patient plasma and normal pooled plasma, but in three additional patients it was evident only after a two-hour incubation. Fifteen of 18 samples showed correction of the abnormal screening study when platelets were used as a source of phospholipid. Both the tissue thromboplastin inhibition test and dilute Russell viper venom times were sensitive assays, being abnormal in 20 of 21 and 13 of 14 samples, respectively. In four patients, discordance of studies necessitated specific coagulation factor levels being measured to confirm the presence of the inhibitor. Because of the variable effect of the inhibitors on all currently available assay procedures, we would suggest that any evaluation will require a laboratory to have a battery of tests available before such an inhibitor can be excluded.
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PMID:The laboratory diagnosis of lupus anticoagulants. 210 43


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