Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0033036 (APC)
 10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thirty-three women who were planned for an in vitro fertilization (IVF) cycle donated blood at four time points during treatment: at baseline, after downregulation, hyperstimulation and luteal support. Levels of progesterone, 17beta-oestradiol and indicators of the protein C pathway, i.e. activated protein C sensitivity ratios (APCsr), protein C, protein C inhibitor and protein S were measured. Compared with baseline, oestradiol decreased twofold at downregulation and increased 40-fold at hyperstimulation. Progesterone was elevated 2.5-fold at hyperstimulation and 40-fold at luteal support. The APCsr increased slightly at downregulation, significantly increased during hyperstimulation and remained high during luteal support. The plasma levels of the anticoagulant proteins did not change or changed moderately during treatment. During downregulation, progesterone correlated negatively with APCsr (r = -0.398, P = 0.024). At hyperstimulation oestradiol correlated with the APCsr (r =0.615, P < 0.0005). Moreover, there was a significant correlation (r = 0.599, P < 0.0005) between the difference in baseline and hyperstimulation values of oestradiol (Delta E2 = 6.6 nmol/l) and the APCsr (Delta APCsr = 0.30). Six women who participated in this study became pregnant. Compared with baseline, the APCsr was increased 1.9-fold (Delta APCsr = 1.48) and free protein S free level decreased 30% at 7 weeks of pregnancy. This study demonstrates that despite the considerable changes in endogenous oestradiol and progesterone during an IVF cycle, changes in plasma levels of anticoagulant proteins are moderate. The significant increase in the APCsr during hyperstimulation indicates that acquired APC resistance observed during sex steroid hormone changes in women is at least partially caused by high oestrogen levels. Our findings demonstrate that IVF treatment is accompanied by the development of a mild prothrombotic condition.
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PMID:Effect of in vitro fertilization treatment and subsequent pregnancy on the protein C pathway. 1170 42

The normalized activated protein C sensitivity ratio (nAPC-sr) determined with an assay that quantifies the effect of APC on thrombin formation initiated via the extrinsic coagulation pathway identifies hereditary and acquired defects of the protein C system. We investigated the influence of assay conditions (analytical variables) and plasma handling (pre-analytical variables) on nAPC-sr obtained with this APC resistance test. The effect of the analytical variables (CaCl2, phospholipid and APC concentrations and the concentration and source of tissue factor) was determined in pooled normal plasma. Inhibition of thrombin formation by APC was dependent on the APC concentration and was also affected by the tissue factor, Ca2+ and phospholipid concentrations. Thus, strict standardization of reactant concentrations is required to obtain reproducible nAPC-sr. Three different tissue factor preparations were compared by determining nAPCsr in plasma samples obtained from 90 healthy individuals. nAPC-sr were similar for all three tissue factor preparations although, compared with the noncommercially available tissue factor used in earlier studies, values determined with commercial tissue factor preparations showed larger variation. Pre-analytical variables, investigated in plasma of nine volunteers (3 normal individuals and 6 individuals with an APC-resistant phenotype) were: concentration of anticoagulant (3.2% vs. 3.8% trisodiumcitrate), time before processing of blood (0, 4 and 24 h), centrifugation speed, storage temperature of plasma (-20 degrees C vs. -80 degrees C) and sample thawing. Multiple linear regression analysis showed that only the citrate concentration affected the nAPC-sr, which was higher in samples collected in 3.2% trisodiumcitrate than in samples collected in 3.8% trisodiumcitrate.
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PMID:Effects of (pre-)analytical variables on activated protein C resistance determined via a thrombin generation-based assay. 1192 38

Since the majority of thrombophilic defects in women with pregnancy loss are in the protein C pathway, we have prospectively determined the diagnostic value of a protein C global assay in 60 consecutive women with pregnancy loss compared to 61 controls. Protein C activation time normalized ratio (PCAT-NR) in pregnancy loss women was significantly lower than controls (0.74 +/- 0.16 vs. 0.99 +/- 0.2; P < 0.0001). PCAT-NR lower than cut off level of 0.8 were found in 42/60 (70%) of PL women compared to 7/61 (11%) of controls (OR = 18.0, 95% CI: 6.3-53.4, P < 0.0001). Cut-off level of 0.8 successfully identified all pregnancy loss women with abnormality in the protein C pathway (12 factor V Leiden, 7 APC-Resistance without factor V Leiden, 15 low levels of protein S and 1 of protein C). Moreover, PCAT-NR below 0.8 was documented in 15/29 (52%) of PL women without thrombophilic risk factor compared to 3/55 (5%) of controls (OR = 18.6, 95% CI: 4.2-95.2, P < 0.0001). These results suggest that ProC Global may be useful as a screening test for protein C pathway abnormalities and may serve as a new thrombophilic risk factor in women with pregnancy loss.
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PMID:Protein C global assay in the evaluation of women with idiopathic pregnancy loss. 1215 73

Anti-phospholipid (aPL) antibodies (Abs) are well known to be associated with thromboembolic events in patients with systemic lupus erythematosus (SLE). However, the clinical relevance of a PL Abs in patients without SLE (non-SLE) who have venous thromboembolism remains unclear. We evaluated 143 non-SLE patients with a first episode of clinically suspected deep vein thrombosis (DVT) by using objective tests for diagnosing DVT and laboratory tests including the activated protein C resistance (APC-R) test, the factor V Leiden test, and various aPL Abs. The prevalence of acquired APC-R, in which case there was no factor V Leiden mutation, was significantly higher in patients with DVT (15/58 cases, 25.9%, p < 0.0001) than in those without DVT (3/80 cases, 3.7%), and confirmed that acquired APC-R was a strong risk factor for DVT (odds ratio [OR], 8.95; 95% confidence intervals [CI], 2.45-32.7; p < 0.001). Multivariate logistic analysis revealed that the presence of LA, aCL, anti-beta2-glycoprotein I, anti-prothrombin and anti-protein C Abs was not reliable as a risk factor for DVT in non-SLE patients, and that the presence of anti-protein S Abs was the most significant risk factor for DVT (OR, 5.88; 95% CI, 1.96-17.7; p < 0.002). Furthermore, the presence of anti-protein S Abs was strongly associated with acquired APC-R (OR, 57.8; 95% CI, 8.53-391; p < 0.0001). These results suggest that acquired APC-R may reflect functional interference by anti-protein S Abs of the protein C pathway, which action may represent an important mechanism for the development DVT in non-SLE patients.
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PMID:Acquired activated protein C resistance associated with anti-protein S antibody as a strong risk factor for DVT in non-SLE patients. 1242 83

Protein C is a member of the vitamin K- dependent protein family. Proteins in this family have similar gamma-carboxyglutamic acid (Gla)-rich domains, but their affinities for negatively charged phospholipid membranes vary more than 1000-fold. We have shown that it is possible to enhance anticoagulant activity and membrane affinity of protein C by selective mutagenesis of the Gla domain. In this study, 3 new mutants, Q10G11N12 (QGN), S23E32D33Y44 (SEDY), and Q10G11N12S23E32D33Y44 (QGNSEDY), were created. In plasma-based coagulation assays, the activated form of QGNSEDY (QGNSEDY-APC) demonstrated approximately 20-fold higher anticoagulant activity than wild-type activated protein C (WT APC), while QGN-APC and SEDY-APC did not. Both normal activated factor V (FVa) and FVa Leiden (Arg506Gln) were degraded much more efficiently by QGNSEDY-APC than by WT APC in the presence as well as in the absence of protein S. Binding of protein C variants to negatively charged phospholipid membranes was investigated using light scattering and the BIAcore technique. QGNSEDY demonstrated 3- to 7-fold enhanced binding as compared with WT protein C, suggesting the membrane affinity to be influenced by several residues located at different parts of the Gla domain. The anticoagulant activity as well as phospholipid binding ability was only enhanced when multiple regions of the Gla domain were modified. The results provide insights into the molecular mechanisms that are involved in determining the binding affinity of the interaction between Gla domains and phospholipid membranes. The unique properties of QGNSEDY-APC suggest this APC variant possibly to have greater therapeutic potential than WT APC.
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PMID:Gla domain-mutated human protein C exhibiting enhanced anticoagulant activity and increased phospholipid binding. 1244 55

The role played by a hypercoagulable state, either inherited or acquired, in the pathogenesis of upper-extremity deep vein thrombosis (UEDVT) remains a question of debate. We performed a case-control study including 79 patients with a first objectively confirmed episode of UEDVT, 31 secondary and 48 primary, and 165 healthy controls. Nine patients (11.4%) with UEDVT were carriers of the prothrombin G20210A mutation vs. six (3.7%) in controls; P = 0.025, OR: 3.39 (95% CI 1.16 to 9.88). No statistical difference was observed between cases and controls for the factor V Leiden mutation, AT, protein C or protein S deficiency and anticardiolipin antibodies (ACAs). Thirteen (35.1%) UEDVT patients were oral contraceptive (OC) users vs. 12 (16%) controls; P = 0.020, OR: 2.89 (95% CI 1.16-7.21). When secondary UEDVT patients were compared with controls, no differences were observed in any of the risk factors analysed. On the other hand, when primary UEDVT was considered, six (12.5%) patients were carriers of the prothrombin G20210A mutation vs. six (3.7%) controls; P = 0.031, OR: 3.76 (95% CI 1.15-12.26). Regarding ACAs, a borderline statistical significance was observed when primary UEDVT was compared with controls, P = 0.048; OR: 4.88 (95% CI 1.05-22.61). In primary UEDVT, 52% of the fertile women were OC users vs. 16% of controls; P = 0.001, OR: 5.78 (95% CI 2.13-15.67). When the interaction of both factors, i.e. prothrombin G20210A mutation and OC intake, were considered, the risk increased markedly, indicating a synergistic effect as observed with other thrombotic locations. In patients with primary UEDVT screening for antithrombin, protein C and protein S deficiency and APC resistance would not be justified, although it might be reasonable to determine the carrier status of the prothrombin G20210A mutation only in OC users.
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PMID:Prothrombin G20210A mutation and oral contraceptive use increase upper-extremity deep vein thrombotic risk. 1262 27

Inflammatory and procoagulant host responses are closely related in sepsis. The protein C pathway serves as a regulatory pathway with anti-inflammatory and anticoagulant properties. Recently, recombinant human activated protein C (rhAPC) was shown to reduce mortality in severe sepsis. Nevertheless, the effects of rhAPC in humans are still ill defined. The infusion of low endotoxin doses into humans provides a standardized model to study inflammatory and hemostatic mechanisms. Thus, we investigated whether rhAPC acts as an anticoagulant or anti-inflammatory drug in human endotoxemia. There were 24 volunteers randomized to receive either 24 microg/kg per hour rhAPC or placebo intravenously for 8 hours. Lipopolysaccharide (LPS, 2 ng/kg) was administered 2 hours after starting the infusions. rhAPC decreased basal tissue factor (TF)-mRNA expression, and thrombin formation and action. In contrast, rhAPC did not significantly blunt LPS-induced thrombin generation. Consistently, rhAPC did not reduce LPS-induced levels of TF-mRNA or D-dimer and had no effect on fibrinolytic activity or inflammation. Finally, endogenous APC formation was enhanced during endotoxemia and appeared to be associated with inflammation rather than thrombin formation. In conclusion, even low-grade endotoxemia induces significant protein C activation. Infusion of rhAPC decreases "spontaneous" activation of coagulation but does not blunt LPS-induced, TF-mediated coagulation in healthy volunteers, which is in contrast to a number of anticoagulants.
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PMID:Recombinant human activated protein C (rhAPC; drotrecogin alfa [activated]) has minimal effect on markers of coagulation, fibrinolysis, and inflammation in acute human endotoxemia. 1275 Jan 66

Acute myocardial infarction is a very rare event during pregnancy and bears the problem of misdiagnosis. However, about 150 cases have been published worldwide with a preponderance of anterior wall infarcts. With more women delaying childbearing until an older age and increasing prevalence of smoking in young women, it can be expected that all forms of coronary artery disease--including acute myocardial infarction--will be seen more often in the future. Among the causes of coronary artery occlusion in pregnancy are (1) rupture of very small coronary artery plaques triggered by different events, e.g., hypertension; (2) plain coronary artery disease; (3) dissection of coronary arteries; (4) coronary artery spasms with/without arterial thrombosis. Prompt diagnosis and immediate therapy are necessary to lower the high mortality of mother and fetus. The gold standard in the therapy of acute myocardial infarction during pregnancy is immediate coronary angiography and percutaneous transluminal coronary angioplasty (PTCA) with or without stent implantation. Application of thrombolytics (recombinant tissue plasminogen activator [rt-PA], r-PA, streptokinase [SK], urokinase [UK]) has been reported in single patients but should be limited to cases where acute PTCA is not available and where the infarct occurs before the 14th week of pregnancy because of possible embryopathy. If the patient is in the last 10 weeks of pregnancy, anticipation of delivery should be part of the medical planning. Consultation with an obstetrician must be obtained as soon as the patient enters the hospital. Besides bleeding complications, venous thrombosis with pulmonary embolism is among the most common causes of death during pregnancy. Pregnancy-related changes in physiology - increase in the resistance to flow from the lower extremities to the heart - and congenital coagulation abnormalities are most important to be recognized. This leads to the fact that superficial and deep venous thromboses occur more often in pregnancy than in the nonpregnant state. Among the coagulation abnormalities found in pregnancy are hypercoagulability (increased levels of fibrinogen, factor VII, factor VIII, factor X), decreased fibrinolytic activity due to an increased level of plasminogen activator inhibitor, increased adhesion and aggregation of platelets, decreased level of protein C and of the APC (activated protein C) ratio. Individual risks factors justifying diagnostic screening include contraception, smoking, immobilization, infection, adiposity, placental insufficiency, and a family history of thrombosis. It is even more important to establish/rule out the diagnosis of thrombosis in pregnancy than in the nonpregnant state, because the use of anticoagulants carries certain risks during pregnancy. Doppler vein studies should be used for diagnosis. If necessary, venography may be used with shielding of the maternal abdomen. Therapy consists of subcutaneous application of heparin, compression, and early mobilization. Alternatively, especially for long-term management, treatment with low molecular weight heparins is feasible. Thrombolytic treatment is contraindicated in most cases due to the high risk of bleeding complications. However, the application of thrombolytics can be contemplated in single cases after careful consideration of the pros and cons. Most cases of pulmonary embolism should also be handled conservatively with heparin. Only in massive pulmonary embolism with severe hemodynamic compromise, thrombolytic treatment is indicated. To guide future therapy in the patients, it is necessary to establish the lifetime risk of recurrent events by determining: APC resistance, prothrombin mutation 20210 A, homocysteine, AT III, protein C and S, antiphospholipid antibodies, and anticardiolipin antibodies.
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PMID:[Myocardial infarction and thromboembolism during pregnancy]. 1275 75

Hereditary thrombophilia is caused by various inherited disorders. Most lead to a familial tendency to recurrent venous, not arterial, thrombosis, usually at a young age, and with spontaneous onset. Most of the genetic defects known today affect the function of natural anticoagulant pathways, in particular, the protein C system. In this study, 602 (265 female, 337 male) patients with suspected thrombosis, arterial or venous, were referred to King Hussein Medical Center in Amman, Jordan. The prevalence of hereditary deficiencies of antithrombin (AT), protein S (PS), and protein C (PC) were studied over a seven-year period (1993-2000). Activated protein C (APC-R) resistance subjects were studied over four years (1996-2000). The mean age was 30 years in females and 42 years in males. A diagnosis was established in 22.4% (n = 135) of the subjects (20.3% venous, 2.1% arterial). Protein C deficiency was found in 3.8%, protein S deficiency in 2.3% and antithrombin deficiency in 1.4% of our sample group. An APC-R problem was seen in 23.0% (n = 89) of the surveyed population. Out of the APC-R patients, 75.0% had the DNA analysis of a factor V Leiden mutation present. Of the subjects found to have the mutation 87.0% were heterozygous and 13.0% were homozygous. These results confirm that APC-R, as a result of factor V Leiden mutation, is the most prevalent cause of thrombosis, and thrombophilia is related to venous, not arterial, thrombosis.
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PMID:Hereditary deficiencies of antithrombin III, protein S, and the protein C pathway in Jordanian thrombosis patients. 1277 77

The presence of lupus anticoagulant has been implicated in venous as well as arterial thrombosis. We report here a 10-year-old boy who presented to us with hematemesis, malaena and splenomegaly. An ultrasound showed a recanalized portal vein with collaterals suggestive of portal vein thrombosis. He had grade IV esophageal varices. The liver function tests were normal. Investigations for prothrombotic factors showed that tests for PNH and for APC resistance were negative. Levels of anti-thrombin II and protein C were normal. There was a prolonged activated partial thromboplastin time with a normal prothrombin time. Presence of lupus anticoagulant was confirmed with dilute Russell viper venom time and platelet neutralization test. Repeat tests after 10 weeks showed persistence of the lupus anticoagulant. ELISA test for anti-phospholipid antibody was negative. The association of lupus anticoagulant with portal vein thrombosis in the pediatric age group is very rare.
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PMID:Extra hepatic portal vein thrombosis in a child associated with lupus anticoagulant. 1284 15


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