Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.69 (APC)
 16,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report a patient who had an ischemic stroke aged 22 years, an inherited type I protein C deficiency and a heterozygous genotype of prothrombin gene 20210A. In view of recent reports of an increased risk for ischemic cerebral vascular disease in patients with the prothrombin 20210A mutation, we suggest that many of the reported cases of ischemic stroke and protein C deficiency may have had additional prothrombotic disorders such as the prothrombin mutation. The current data concerning the magnified risk for stroke in patients with the prothrombin 20210A mutation suggests the need to study all patients with premature stroke for this mutation and the other risk factors for thrombosis. This would include homocysteine, lupus inhibitor, anticardiolipin antibodies, and possibly the natural inhibitors of coagulation. It is possible that patients with the prothrombin 20210A mutation and ischemic cerebral vascular disease would benefit from long-term anticoagulation therapy in a similar way to patients with the antiphospholipid syndrome.
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PMID:Ischemic stroke in a young patient with protein C deficiency and prothrombin gene mutation G20210A. 989 Jul 20

BACKGROUND: Thrombophilia may be associated with premature atherosclerosis, an increased susceptibility to primary arterial thrombosis and an increased failure rate for peripheral vascular or endovascular interventions. The aim of this study was to determine the prevalence of thrombophilia in patients with intermittent claudication (IC). METHODS: This was a prospective study of 116 consecutive new patients (70 men; median age 65 (range 43-84) years) referred to this regional vascular surgery unit with IC. Patients on warfarin, or who had previously undergone lower limb reconstruction and/or angioplasty, were excluded. RESULTS: Thrombophilia was demonstrated in 24 patients (21 per cent). The commonest abnormality (15 patients, 13 per cent) was a raised level of anticardiolipin antibody (ACLA) (11 immunoglobulin (Ig) M, four IgG). Other abnormalities comprised: lupus anticoagulant (one), protein C deficiency (two), protein S deficiency (two), activated protein C resistance (one) and factor V Leiden heterozygosity (three). All abnormalities were confirmed on repeat testing. No patient had a history of venous thrombosis. There was no statistically significant relationship between ACLA status and age, sex, ankle : brachial pressure index, previous myocardial infarction or stroke, previous carotid endarterectomy or coronary artery surgery, serum cholesterol, current use of antiplatelet agents or current smoking status. CONCLUSION: Almost one-quarter of new patients referred to this regional vascular unit with IC have thrombophilia; over half of those affected have a raised ACLA level compatible with the antiphospholipid syndrome. At present, the clinical significance and management implications of these abnormalities remain unknown.
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PMID:Vascular surgical society of great britain and ireland: prevalence and significance of thrombophilia in patients with intermittent claudication 1036 36

Within the last few years, the knowledge of hereditary and acquired risk factors for venous thromboembolism has increased. Antithrombin-, protein C- and protein S-deficiency have been known since a long time as hereditary risk factors. Since 1993, three hitherto unknown risk factors have been described, the APC (activated protein C) resistance, hyperhomocysteinemia and a polymorphism in the 3-UT region of the prothrombin gene. These risk factors are relatively common in the normal population (in total 10-15%) and are found in 30-50% of patients with venous thromboembolism. The most important acquired risk factor for thromboembolism is the antiphospholipid antibody syndrome (APLS). The APLS is found in around 3% of patients with thromboembolism, patients with these abnormalities have a high risk for recurrency. The upper mentioned risk factors for thromboembolism do not only increase the risk for spontaneous thrombosis, but also the risk for thrombosis during typical high risk situations, such as surgery, trauma of the lower extremities, pregnancy and delivery. APC resistance and antithrombin deficiency increase the risk for development of thrombosis during oral contraceptive intake. Patients, in whom one of the upper mentioned risk factors have been diagnosed, should receive thrombosis prophylaxis during high risk situations. Not all patients with one thromboembolic event and a known risk factor are candidates for long-term oral anticoagulant treatment. Long-term oral anticoagulant treatment should be introduced after exclusion of major contraindications in patients with recurrent events, patients with a combination of risk factors and a life threatening event.
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PMID:[Thromboembolism--genetic and acquired risk factors]. 1047 76

Pregnancy has been widely recognized as a predisposing risk factor for deep vein thrombosis (DVT). However, it still remains unclear why pregnant women without a history of familial thrombophilia or antiphospholipid syndrome (APS) have a higher incidence of DVT and pulmonary embolism (PE) during pregnancy and puerperium. We examined the activated protein C (APC) system in healthy pregnant women and in patients with the onset of DVT during puerperium. Sixty unselected Japanese pregnant women without a past or family history of thrombosis or APS and 3 Japanese women with DVT during puerperium were evaluated. Endogenous thrombin potential-ratio (ETP-r) was measured by determination of thrombin-alpha2-macroglobulin complexes in thromboplastin-activated patient plasma. APC sensitivity ratio (APC-sr) was calculated by the determination of ETP-r in patient plasma in the presence and absence of APC (final concentration [conc.] 5.9 nM) to evaluate the functional APC anticoagulant activity. Mean APC-sr was significantly increased at 30 weeks' gestation (2.35 +/- 0.72) and remained high during puerperium compared with the mean APC-sr in nonpregnant women (1.15 +/- 0.63). Mean APC-sr in patients with DVT at the onset was significantly higher (3.57 +/- 0.54) than mean APC-sr during puerperium was, indicating that the sensitivity to APC was reduced in the ETP-based assay. These data suggest a significant reduction in the functional sensitivity to APC associated with an increased risk of venous thrombosis during pregnancy.
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PMID:Detection of decreased response to activated protein C during pregnancy by an endogenous thrombin potential-based assay. 1062 9

The mechanism of thrombosis in patients with antiphospholipid syndrome is not clear. To investigate it, we examined the effect of monoclonal anticardiolipin (aCL) antibodies and beta2-glycoprotein I (beta2-GPI), which is required for formation of the aCL epitopes, on activated protein C (APC) and on fibrinolytic activity. First, APC activities were measured in the presence and absence of beta2-GPI or gamma M immunoglobulin (IgM) monoclonal aCLs (EY1C8 and EY2C9), or both, established from peripheral blood lymphocytes obtained from a patient with aCL. beta2-GPI exhibited a procoagulant activity by inhibiting APC activity as well as an anticoagulant activity by inhibiting thrombin generation. Any further inhibition of APC activity was caused by monoclonal aCL, and then only in the presence of beta2-GPI. The remaining tissue plasminogen activator (t-PA) of the sample consisting of beta2-GPI, two-chain recombinant t-PA, and plasminogen activator inhibitor (PAI)-1 was measured by a chromogenic assay using the synthetic substrate S-2251, Glu-plasminogen, and soluble fibrin monomer. beta2-GPI protected t-PA activity from inhibition by PAI-1. However, monoclonal aCLs (EY1C8 and EY2C9) inhibited the effect of beta2-GPI on fibrinolytic activity; that is, monoclonal aCLs inhibited fibrinolytic activity by elevating PAI-1 activity. Thrombosis in patients with aCL can be explained in part by both the inhibition of APC anticoagulant activity and the impairment of fibrinolytic activity by aCL.
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PMID:The putative mechanism of thrombosis in antiphospholipid syndrome: impairment of the protein C and the fibrinolytic systems by monoclonal anticardiolipin antibodies. 1062 10

Anticardiolipin (anti-CL) antibodies, diagnostic for antiphospholipid antibody syndrome, are associated with increased risks of venous and arterial thrombosis. Because CL selectively enhances activated protein C/protein S-dependent anticoagulant activities in purified systems and because CL is not known to be a normal plasma component, we searched for CL in plasma. Plasma lipid extracts [chloroform/methanol (2:1, vol/vol)] were subjected to analyses by using TLC, analytical HPLC, and MS. A plasma lipid component was purified that was indistinguishable from reference CL (M:1448). When CL in 40 fasting plasma lipid extracts (20 males, 20 females) was quantitated by using HPLC, CL (mean +/- SD) was 14.9 +/- 3.7 microgram/ml (range 9.1 to 24.2) and CL was not correlated with phosphatidylserine (3.8 +/- 1.7 microgram/ml), phosphatidylethanolamine (64 +/- 20 microgram/ml), or choline-containing phospholipid (1,580 +/- 280 microgram/ml). Based on studies of fasting blood donors, CL (>/=94%) was recovered in very low density, low density, and high density lipoproteins (11 +/- 5.3%, 67 +/- 11.0%, and 17 +/- 10%, respectively), showing that the majority of plasma CL (67%) is in low density lipoprotein. Analysis of relative phospholipid contents of lipoproteins indicated that high density lipoprotein is selectively enriched in CL and phosphatidylethanolamine. These results shows that CL is a normal plasma component and suggest that the epitopes of antiphospholipid antibodies could include CL or oxidized CL in lipoproteins or in complexes with plasma proteins (e. g., beta(2)-glycoprotein I, prothrombin, protein C, or protein S) or with platelet or endothelial surface proteins.
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PMID:Cardiolipin is a normal component of human plasma lipoproteins. 1067 28

According to a recent hypothesis, venous thrombosis results from the concurrence of several factors. This hypothesis was assessed in patients with portal or hepatic venous thrombosis by simultaneously investigating most of the currently identified prothrombotic disorders, local precipitating factors, and other risk factors such as oral contraceptive use. Patients with a tumorous obstruction and patients with cirrhosis with portal vein thrombosis were excluded. The prothrombotic disorders that were investigated included classical and occult myeloproliferative disorders; antiphospholipid syndrome; protein C; protein S and antithrombin deficiency; factor V Leiden; factor II; and methylene-tetrahydrofolate-reductase gene mutations. We found 1 or several prothrombotic disorders and a local precipitating factor in 26 and 10 of the 36 patients with portal vein thrombosis, respectively; and in 28 and none of the 32 patients with hepatic vein thrombosis, respectively. We found a combination of prothrombotic disorders in 5 and 9 patients with portal and hepatic vein thrombosis, respectively, whereas such a combination is expected in less than 1% of asymptomatic subjects. Of the 10 patients with a local precipitating factor, 8 had a prothrombotic disorder. Of the 13 patients who use oral contraceptives, 10 had a prothrombotic disorder. We conclude that portal or hepatic venous thrombosis should be regarded as an index for 1 or several prothrombotic disorders, whether or not local precipitating factors or oral contraceptive use are found. Concurrence of prothrombotic disorders is more common than expected. Extensive investigation of prothrombotic disorders and anticoagulation should be considered in patients with portal or hepatic venous thrombosis.
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PMID:Cause of portal or hepatic venous thrombosis in adults: the role of multiple concurrent factors. 1070 47

Recurrent thrombosis is a common complication of various rheumatic disorders and is part of the definition of antiphospholipid syndrome. We report three cases of recurrent venous thrombosis due not only to antiphospholipid syndrome with a normal activated partial thromboplastin time but also to resistance to activated protein C caused by the factor V Leiden mutation. These three cases confirm that thrombotic disease is frequently multifactorial and suggest that resistance to activated protein C should be looked for routinely in patients with suggestive clinical manifestations, particularly when standard clotting tests are normal.
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PMID:Antiphospholipid syndrome and factor V Leiden. Three cases with recurrent venous thrombosis. 1076 7

Antiphospholipid antibodies are well recognized as associated with serious clinical complications such as arterial and venous thrombosis and recurrent spontaneous abortion. These complications are collectively called antiphospholipid syndrome(APS). The mechanisms responsible for the thrombosis are unclear. We reported three mechanisms. beta 2-glycoprotein I(beta 2GPI) inhibited activated protein C(APC) activity and, furthermore, APC activity decreased by the addition of monoclonal aCL and beta 2GPI. Monoclonal anticardiolipin antibodies(aCL) seemed to enhance the inhibition of APC procoagulant activity caused by beta 2GPI. Monoclonal aCL in the presence of beta 2GPI also increased the activity of plasminogen activator inhibitor(PAI)-1 in the mixture of tissue-plasminogen activator(t-PA) and PAI-1 by inhibiting the function of beta 2GPI, which increased the remaining t-PA activity in the mixture. The formation of thrombin-antithrombin complexes(TAT) in APS was impaired. The level of TAT in APS did not increase, however the level of prothrombin fragment 1 + 2 (F1 + 2) increased. Therefore, free thrombin present in patients' blood may contribute to thrombosis in APS. These reports indicate that thrombosis in APS may be caused by several thrombogenic factors that stimulate aCL.
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PMID:[Antiphospholipid antibodies and thrombosis: the putative mechanisms of hypercoagulable state in patients with anticardiolipin antibody]. 1081 Aug 73

The antiphospholipid syndrome is an acquired prothrombotic state where thrombosis and/or pregnancy loss is related to the presence of antiphospholipid antibodies. Cutaneous necrosis secondary to intravascular thrombosis of small dermal vessels is a recognized but rare association with antiphospholipid syndrome. We report two patients with high circulating levels of anticardiolipin antibodies who developed widespread cutaneous necrosis as the first clinical manifestation of the antiphospholipid syndrome. The exact mechanism by which antiphospholipid antibodies mediate thrombosis is uncertain; however, proposed mechanisms of activity include endothelial cell activation, altered endothelial production of prostacyclin, activation of platelets, and modulation of the protein C and S pathways.
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PMID:Widespread cutaneous necrosis occurring in association with the antiphospholipid syndrome: a report of two cases. 1084 28


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