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

Proteins C and S are two vitamin K-dependent plasma proteins that work in concert as a natural anticoagulant system. Activated protein C is the proteolytic component of the complex and protein S serves as an activated protein C binding protein that is essential for assembly of the anticoagulant complex on cell surfaces. The anticoagulant activity is expressed through the selective inactivation of Factors Va and VIIIa. Many patients deficient in proteins C and S have been described and have an associated thrombotic tendency, but not all heterozygous protein C and S deficient individuals experience thrombotic complications. Multiple mechanisms and/or drugs can lead to acquired deficiencies of these proteins: oral anticoagulation, liver disease, DIC and in the case of protein S, lupus erythematosus, nephrotic syndrome, pregnancy and certain hormones. The anticoagulant activity of protein C decreases rapidly after administration of warfarin (i.e., with a time course similar to Factor VII). This rapid decrease may lead to a transient imbalance and contribute to coumarin induced skin necrosis. Protein S antigen levels do not decrease as rapidly, but protein S functional levels are often low in patients with an acute thrombus. The discrepancy between antigen and function results from elevations in C4b-binding protein, which complexes reversibly with protein S. Unlike free protein S, the complex does not function in the anticoagulant pathway. The available information all suggest that deficiency of protein C and protein S should be considered a risk factor contributing to recurrent thrombotic disease and that the function of these proteins is altered by many common clinical conditions which have associated an increased risk of thrombosis.
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PMID:Anticoagulation proteins C and S. 295 34

Protein S, an important cofactor of activated protein C, and C4b-binding protein were purified from human plasma. Specific antibodies against the purified proteins were raised in rabbits and used for the development of immunologic assays for these proteins in plasma: an immunoradiometric assay for protein S (which measures both free protein S and protein S complexed with C4b-binding protein) and an electroimmunoassay for C4b-binding protein. Ranges for the concentrations of these proteins were established in healthy volunteers and patients using oral anticoagulant therapy. A slight decrease in protein S antigen was observed in patients with liver disease (0.78 +/- 0.25 U/ml); no significant decrease in protein S was observed in patients with DIC (0.95 +/- 0.25 U/ml). Criteria were developed for the laboratory diagnosis of an isolated protein S deficiency.
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PMID:Determination of plasma protein S--the protein cofactor of activated protein C. 316 Dec 6

Using a new rapid coagulant method, protein C activity (PC act) was determined in liver cirrhosis and malignancies and compared with PC antigen and AT III values. PC was decreased in a more pronounced manner than AT III in liver cirrhosis, mainly due to impaired synthesis. This is of special clinical interest because PC proved to be a high sensible indicator of liver cell dysfunction. Decreased levels of PC act (PC ratio act/ag less than 1) in decompensated liver cirrhosis may be caused by the synthesis of dysfunctional PC and/or vitamin K deficiency with production of undercarboxylated PC most sensitively registered by this coagulant assay. An increased clearance of in vivo activated PC induced by DIC may play an insignificant role. In patients with liver metastases, PC act (but not AT III and immunological parameters) was significantly reduced, supporting the conclusion that in these patients liver dysfunction concomitant with synthesis of dysfunctional PC must be discussed as the main cause of this alteration.
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PMID:Immunological and functional determination of the protease inhibitors, protein C and antithrombin III, in liver cirrhosis and in neoplasia. 320 4

Protein C (PC) activities measured by two thrombin-based assays have been compared with those obtained by two assays based on snake venom activation of plasma PC followed by measurement of both the amidolytic and anticoagulant activities of activated PC. This study indicates that snake venom assays gave results similar to those of the thrombin assays in 20 healthy subjects, in 16 patients with DIC and in 15 patients with congenital PC deficiency. There was, however, some degree of misclassification of normals and congenitally-deficient patients, with only the clotting snake venom assay resulting in no misclassifications. In 15 patients stabilized on warfarin treatment and in 17 with liver disease, the clotting snake venom assay gave significantly lower values than the other assays, so that it might prove to be more sensitive than the other assays to these defects.
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PMID:Functional assays of protein C: comparison of two snake-venom assays with two thrombin assays. 321 14

Protein C and protein S serve as natural anticoagulants. Deficiencies of these proteins are often associated with recurrent deep vein thrombosis and coumarin induced skin necrosis. These two proteins function by selectively inactivating factors Va and VIIIa, two of the "cofactors" of blood coagulation. Hence, inhibition of coagulation by this pathway complements the better known inhibition mediated by the antithrombin III-heparin system. These observations suggest that protein C and/or activated protein C may prove useful in controlling thrombosis and/or DIC. We have developed a Ca2+ dependent monoclonal antibody which allows the rapid isolation of human protein C. This rapid isolation has allowed us to demonstrate that activated protein C can protect baboons from the lethal effects of E. coli/endotoxin and that protein C supplementation can minimize fibrinogen consumption following tissue factor infusion into dogs.
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PMID:Protein C, isolation and potential use in prevention of thrombosis. 330 68

Patients who are severely envenomed by Russell's viper develop DIC which is frequently associated with spontaneous bleeding and incoagulable blood. These haemostatic disturbances may be responsible for death or organ/tissue damage both through haemorrhage and microvascular occlusion by fibrin thrombi. The most striking laboratory features of the coagulopathy developing after Russell's viper bite in the 42 patients studied were depletion of fibrinogen (mean 0.09 g/l, range 0-0.6), factor V (6.5 u/dl, range 0-17), factor X (35 u/dl, range 1-85), factor XIIIa (57 u/dl, range 15-82), plasminogen (61 u/dl, range 10-92), antiplasmin (36 u/dl, range 14-62). Protein C (49 u/dl, range 15-100) and platelets (104 x 10(9)/l, range 25-197). Intense fibrinolytic activity was detected in all cases with marked elevation of FDPs (1614 micrograms/ml, range 350-3000), a large proportion of which were cross-linked (1058 micrograms/ml, range 38-3000). The monospecific Burmese antivenom appeared to be very effective in neutralizing the venom procoagulants and in restoring blood coagulability. Moreover, the unexpectedly normal level of AT III provides a theoretical basis for the use of heparin to enhance the inactivation of those serine proteases present before antivenom administration.
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PMID:Haemostatic disturbances in patients bitten by Russell's viper (Vipera russelli siamensis) in Burma. 340 87

A new practicable and precise functional protein C evaluation test is based on the activation of protein C by a snake venom activator and determination of PC activity by its property to prolong the aPTT in a clotting assay (VK = 1.9% and 4% for intra- and interassay variance respectively). In 40 healthy controls there was a good correlation (r = 0.74) between the functional and immunological (ELISA) evaluation. In 123 patients with both evaluation methods but more pronounced with the measurement of the protein C activity a significant protein C deficiency was found in the patient groups with disseminated solid tumors, inflammatory diseases and myocardial infarction. Besides detection of hereditary PC deficiency Type II (generation of functionally abnormal PC) the functional assay profits by recording PC inhibitor complexes and otherwise dysfunctional PC in DIC. Thus, in patients with hematological neoplasias, only protein C activity was significantly decreases. Decrease of PC activity was more pronounced compared to PC Ag in liver disease indicating synthesis of functionally deficient PC, and in oral anticoagulant treatment due to detection of PIVKA-PC.
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PMID:[Immunologic and functional protein C determination in various internal diseases]. 343 Oct 26

Severe homozygous protein C deficiency is a rare but serious problem in the newborn, with a clinical presentation of purpura fulminans. We have presented such a case in an 1,870 gm female neonate. Salient clinical findings in this case include DIC associated with extensive ecchymosis and subsequent gangrene of the skin, thrombotic complications that began on the third day of life. There was no precipitating infection. The progressive gangrenous necrosis of heel and toes was refractory to heparin therapy, but there was clinical improvement after treatment with fresh frozen plasma. Our patient's level of protein C antigen was less than 3% (normal 70% to 130%). Levels of other vitamin-K-dependent factors, as well as factor V, factor VIIIC, and antithrombin III were normal. A heterozygous protein C deficiency was documented in the mother and father. Presently the child is receiving warfarin sodium (Coumadin) therapy and is clinically stable.
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PMID:Protein C deficiency. 381 Feb 23

Human protein C is the central protein of an important regulatory mechanism, as shown by the high incidence of thromboembolic complications in congenital deficiencies of protein C. Both abnormal molecules and half-normal levels of protein C antigen and activity have been found in patients with familial thrombotic complications. Newborn infants with congenital homozygous protein C deficiency develop catastrophic thrombosis (purpura fulminans) and will not survive beyond the neonatal period without protein C replacement. Individuals with systemic thrombosis have significantly decreased levels of protein C concomitant with the severity of the DIC. These studies suggest that protein C is important not only in the congenital deficiencies, but also in acquired deficiencies, such as during DIC or possibly the postsurgical hypercoagulable state.
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PMID:Protein C in thromboembolic disease. 384 Sep 18

An enzyme-linked immunosorbent assay (ELISA) for measuring human protein C by using two monoclonal antibodies directed toward the heavy chain of protein C is reported. This assay enabled the determination of protein C in concentrations of 10 to 400 ng/ml in less than 3 hours with a single antigen-antibody reaction. Within-run and between-run coefficients of variation were less than 8%. The mean concentrations of protein C in plasma of 42 normal subjects, 24 patients with liver disease, 27 with DIC, 48 with warfarin therapy and 15 with congenital protein C deficiency, were 4.2, 3.0, 2.3, 2.1 and 1.9 micrograms/ml, respectively. The results obtained with the present ELISA correlated well with those of radioimmunoassay (r = 0.935, n = 81) as well as those of Laurell's Rocket method (r = 0.910, n = 81) by using rabbit anti-human protein C serum. The present method was sensitive and specific for measurement of protein C and also PIVKA-protein C in plasma.
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PMID:Enzyme immunoassay of human protein C by using monoclonal antibodies. 389 62


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