Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.6 (thromboplastin)
13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An acquired inhibitor of blood coagulation, similar to that described in patients with Systemic Lupus Erythematosus (SLE), was detected during routine coagulation screening in 10 patients who did not meet the criteria for a diagnosis of SLE. The lupus-like anticoagulant (LLAC) was diagnosed on the basis of prolonged activated partial thromboplastin time (APTT) and/or prothrombin time (PT) which failed to correct when patient plasma was added to normal plasma; an additional criterion was an abnormal tissue thromboplastin inhibition test. No patient had a specific inhibitor directed against factors VIII and IX. Demonstration of LLAC was highly dependent upon the type of reagents adopted in the APTT and PT: the abnormality was detected consistently by one reagent only. One-stage assays of factors VIII and IX were characteristic of the presence of an inhibitor, showing non-parellel dose-response curves or decreased activity at low dilutions which were partially corrected at higher dilutions. Although 7 patients were free of abnormal bleeding, unequivocal signs of haemorrhagic tendency after a surgery were present in the remaining 3 patients. The findings suggest that LLAC is a non-exceptional cause of prolonged coagulation screening tests, and that it may sometimes be associated with impaired haemostasis.
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PMID:The varied sensitivity of partial thromboplastin and prothrombin time reagents in the demonstration of the lupus-like anticoagulant. 47 62

We studied a patient being treated with procainamide in whom we observed a high antinuclear antibody titer and prolonged activated partial thromboplastin (PTT), prothrombin (PT), and Stypven times (ST). Serum antibody concentrations against single-stranded DNA were elevated while those aginst native DNA were not elevated, suggesting the procainamide-induced lupus syndrome. Dilution of the patient's plasma with normal plasma failed to correct the PTT and PT, indicating the presence of an inhibitor(s) to blood coagulation. The anticoagulant activity was associated with the IgG fraction of the patient's serum. Addition of purified or partially purified human factors IX, X, VIII, VII, XIa, prekallikrein, high molecular weight kininogen, or phospholipids to the patient's plasma failed to correct the PTT, PT, or ST; however, purified human factor XII and prothrombin corrected the PTT and ST, respectively. These results indicate that production of antibodies directed against antigenic determinants on coagulation proteins can be a manifestation of procainamide-induced lupus erythematosus.
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PMID:Circulating inhibitors of blood coagulation associated with procainamide-induced lupus erythematosus. 71 99

A lupus-type anticoagulant which causes strong inhibition of the partial thromboplastin time with kaolin (PTTK), the stypven time, and the thrombin generation tests has been investigated. All tests for platelet function were normal, as were all specific coagulation factor assays with the exception of a slightly reduced factor XI in this patient. A diethylaminoethyl-cellulose-immunoglobulin (DEAE-cellulose-IgG) fractionation of the patient's plasma produced two peaks containing inhibitory activity in the PTTK test. The first of these peaks had a cloudy appearance, suggesting the presence of immunoglobulin aggregates. Studies with IgG aggregates prepared from normal IgG and from the patient's IgG demonstrated that such aggregates were not the cause of inhibition. It was possible to neutralize the inhibitory activity of the purified IgG but not platelet-poor plasma (PPP) with a rabbit anti-IgG. The inhibition of the patient's PPP in the thrombin generation, the contact product, and the stypven time tests were corrected by the inclusion in the test system of platelets activated either by aggregation due to adenosine diphosphate (ADP) or formalin fixation and washing. These studies lend support to earlier findings that platelets interact at several sites in the coagulation cascade.
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PMID:Demonstration of a platelet bypass mechanism in the clotting system using an acquired anticoagulant. 73 36

Eighty-three patients with circulating anticoagulants were studied at The New York Hospital. The lupus-type anticoagulant, an inhibitor of the prothrombin activator complex, was demonstrated in 58 patients. The inhibitor was identified using the blood and tissue thromboplastin inhibition tests. Inhibition by the lupus anticoagulant was augmented in 67% of these patients by a cofactor present in normal plasma. The lupus inhibitor was detected primarily because of an unsuspected abnormal coagulation test. One-half of the patients with the lupus-type anticoagulant did not have systemic lupus erythematosus.
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PMID:A clinical study of the lupus anticoagulant. 96 90

Prevalence of lupus anticoagulant (LA) in patients with systemic lupus erythematosus (SLE) and clinical manifestations vary widely between different clinical series. We investigated the relation between LA, autoimmune hemolytic anemia (AIHA), thrombocytopenia and platelet dysfunction in 80 unselected patients with SLE. AIHA was found in 6 patients (7.5%) and thrombocytopenia in 10 patients (12.5%), which was not related to platelet aggregation abnormalities. Compared to controls, patients with SLE showed significantly prolonged aPTT and kaolin clotting time (KCT), but platelet aggregation induced by both collagen and thrombin was not impaired. LA activity as defined by Rosner et al. (index for LA/ICA) was found in 15 patients (18.9%). Only 7 of these patients showed a positive platelet neutralization test (Triplett) and 9a positive tissue thromboplastin inhibition test (Schleider). In our SLE patients 23.7% have suffered from at least one thrombotic complication. In patients with LA activity thromboembolic complications were increased (p < 0.05). Thrombocytopenia was found in 6% of LA-negative but in 20% of LA-positive patients.
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PMID:[Prevalence of lupus anticoagulant, autoimmune hemolysis, thrombocytopenia and disorders of platelet function in unselected patients with SLE]. 128 63

Citrated samples from 100 patients on i.v. heparin and 20 normal patients were tested with three batches each of three activated partial thromboplastin time (APTT) reagents: Thrombosil I (Ortho); Automated APTT (Organon Teknika) and Actin FSL (Baxter). The ratio of APTT over the geometric mean normal APTT for each heparinized sample was calculated. One batch of reagent arbitrarily chosen as a reference gave the ratios APTRREF (y). The remaining reagents to be standardized against the reference system gave the ratios APTRTEST (x). The best correlation between systems was given by log vs log x. Standard curves were prepared from the APTT ratios of the 20 normal patients and 65 of the heparinized samples. On plotting log APTRTEST vs log APTRREF the y intercept was close to zero so x was expressed in terms of y using; log x = HSI. log y, where HSI (Heparin Sensitivity Index) = slope. The APTRTEST results of the remaining 35 heparinized samples were transformed using; APTRTRANS = (APTRTEST)HSI.APTRTRANS was then compared to APTRREF to determine whether the transformation brought the results closer to the reference. We conclude that although some improvement was found by using the transform, it was not possible to mathematically relate APTT results due to a high degree of variation between results using different reagents. A standard APTT reagent for the monitoring of heparin therapy is recommended. A separate APTT reagent may be required for the screening of factor deficiencies and lupus anticoagulants.
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PMID:An attempt to standardize APTT reagents used to monitor heparin therapy. 133 84

The incidence of anticardiolipin (ACL) antibodies in connective tissue disorders other than systemic lupus was investigated in 113 subjects: 68 had rheumatoid arthritis, 23 primary Sjogren syndrome and 22 had systemic sclerosis. VDRL, thromboplastin time and determination of IgG and IgM ACL antibodies (ELISA) were performed in all subjects. Overall, 45% of patients were positive for ACL antibodies, mostly of the IgG variety (90%). No differences were observed among the investigated diseases. Positive ACL antibodies were not related to evidence of antiphospholipid syndrome nor to clinical characteristics of the different diseases. These results confirm that ACL antibodies may be present in connective tissue disorders other than systemic lupus, but they do not predict the development of antiphospholipid syndrome nor help to characterize the severity of the disease.
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PMID:[Anticardiolipin antibodies in connective tissue diseases]. 134 74

Antibodies directed against phospholipids are highly associated with episodes of venous and arterial thrombosis, which are often recurrent. There seems to be a skewed frequency of cerebral thrombosis when the arterial circulation is affected. Clinical clues that should lead to evaluation for aPL include stroke in a young adult, recurrent thrombosis or miscarriage, and thrombocytopenia. Associated laboratory abnormalities include a biologically false-positive test for syphilis, abnormal antinuclear antibody titers, and a high erythrocyte sedimentation rate. If the activated partial thromboplastin time is prolonged on routine screening and does not correct with mixing studies, a lupus anticoagulant should be suspected. However, more sensitive and specific tests are usually necessary to detect aPL. Many in vitro and more recently in vivo systems strongly suggest that aPL may be directly implicated in the pathogenesis of thrombosis. Optimal management of patients with aPL-associated thrombosis is unknown. The use of aggressive therapeutic management schemes with such agents as warfarin or corticosteroids is sometimes required.
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PMID:Antiphospholipid antibodies and ischemic stroke. 134 35

A 57-year-old man with no evidence of infection, vasculitis or connective tissue disease died with multiple organ thromboses after an acute illness. He was found to have lupus anticoagulant, IgG anticardiolipin antibody, false positive rapid plasma reagin, prolonged partial thromboplastin time, and thrombocytopenia. Venous and arterial thrombi leading to necrosis were found in his scrotum, testicles, upper and lower extremities, adrenals, kidneys, lungs, and brain. No other explanation could be found for his fatal illness, thus suggesting the primary antiphospholipid syndrome (APS). This is a documented case of primary APS associated with multiorgan arterial and venous thromboses of large and small vessels, presenting as a fulminant and fatal acute illness.
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PMID:Primary antiphospholipid syndrome with multiorgan arterial and venous thromboses. 140 68

The effect of different methods of plasma preparation on the results of 1) a clotting assay for lupus anticoagulant (LA) detection (the dilute activated partial thromboplastin time, dAPTT), and of 2) an ELISA test for anticephalin antibody (aCEPHA) detection, was evaluated. It is well known that platelet disintegration resulting from freeze-thawing of plasma samples may release procoagulant phospholipid--"LA-bypassing" activity. Even with fresh plasma, the dAPTT of LA positive samples was sensitive to the presence of residual blood platelets. This effect was accentuated by freezing and thawing: with test plasma that had been prepared by a centrifugation force of 3,000 g or less for 15 min at 4 degrees C, freeze-thawing caused a significant shortening of the dAPTT. This phenomenon could not be demonstrated with filtered test plasma, which was platelet free. Surprisingly, ultracentrifugation also led to a substantial shortening of the dAPTT compared to filtered plasma, and should not be recommended as a method of plasma preparation for LA detection. The ELISA test was less sensitive to residual platelets than the dAPTT. Thus, plasma prepared by a centrifugation force of at least 1,500 g may be stored at -20 degrees C before performance of the ELISA test. For the dAPTT, filtering of test plasma and control plasma after centrifugation is recommended for maximum sensitivity, regardless of whether they are to be examined in the fresh state or after freezing and thawing.
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PMID:Preparation of plasma for the detection of lupus anticoagulants and antiphospholipid antibodies. 141 82


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