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)

Improved methods are described to obtain bovine prothrombin, Factor IX, Protein C, and autoprothrombin III (Factor X, Auto-III) in purified form. The prothrombin had a specific activity of 4,340 Iowa units/mg. Theoretically, a preparation of clean thrombin should have a specific activity of 8,200 U/mg, because 47.08% of the protein in prothrombin is lost when thrombin forms. Such thrombin preparations have been obtained (Arch. Biochem. Biophys. 121, 372 (1967)). The prothrombin concentration of bovine plasma is near 60 mg/liter. Protein C, first isolated by Stenflo (J. Biol. Chem. 251, 355 (1976)), was found to be the precursor of autoprothrombin II-A (Auto-II-A), discovered earlier (Thromb. Diath. Haemorrh. 5, 218 (1960)). Protein C (Factor XIV) was converted to Auto-II-A (Factor XIVa) by thrombin. Digesting purified Auto-III with purified thrombin removed a small glycopeptide from the COOH-terminal end of the heavy chain to yield Auto-IIIm. Auto-III thrombin leads to Auto-IIIm + peptide. Auto-IIIm was not converted to the active enzyme with thromboplastin, and furthermore, inhibited the activation of purified native Auto-III with thromboplastin. Auto-IIIm was also not converted to the active enzymes when the procoagulants consisted of purified Factor VIII, purified Factor IXa, platelet factor 3 and calcium ions. The "activation peptide" released by RVV-X from the NH2-terminal end of the heavy chain and the active enzyme (Auto-Cm) were purified. Auto-III was also activated with purified RVV-X. The same "actid of Auto-Cm. Purified Factor IX developed anticoagulant activity when reacted with an optimum concentration of purified thrombin. A suitable reagent for the assay of Factor IX was prepared by removing prothrombin complex from anticoagulated bovine plasma and restoring the prothrombin and Auto-III concentration with use of the respective purified proenzymes.
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PMID:Improved procedures for the purification of selected vitamin K-dependent proteins. 78 72

The extent and time course of changes in selected procoagulant and anticoagulant factors were investigated in 19 patients undergoing elective abdominal aortic surgery. The coagulation factors were measured preoperatively, and on days two, four, and six postoperatively. It was found that there were no significant changes outside the normal range in prothrombin time, partial thromboplastin time, or thrombin clotting time. However, there were large increases in the procoagulants, fibrinogen, factor VIII coagulant, factor VIIIRag/von Willebrand factor, and in alpha 1-antitrypsin. Over the same time there were marked decreases in the naturally occurring anticoagulants, protein C and antithrombin III, and in alpha 2-macroglobulin. These changes implied that the patients were "hypercoagulable" in the postoperative period. The maximum changes in the procoagulants occurred on either postoperative day two or day four. The maximum changes in the natural anticoagulants occurred on postoperative day two. There were no significant changes in factor V, factor X, alpha 2-antiplasmin, or platelet aggregability. The timing of the changes coincided with a period of high risk of perioperative myocardial infarction in this group of patients. Thus, it is possible that postoperative hypercoagulability contributes to the development of coronary artery thrombosis and myocardial infarction following abdominal aortic surgery.
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PMID:Postoperative changes in coagulant and anticoagulant factors following abdominal aortic surgery. 128 42

Antiphospholipid antibodies (APA) are a family of immunoglobulins that react with anionic phospholipids, or anionic phospholipids-protein complexes. Recent evidence would support the latter definition. Lupus anticoagulants (LA) inhibit in vitro phospholipid dependent coagulation tests [e.g., activated partial thromboplastin time (APTT), prothrombin time (PT), and dilute Russell viper venom time (dRVVT)]. This inhibition appears to be specific for reagent phospholipids. The addition of freeze-thawed platelets or activated platelets will result in correction of the LA-induced abnormality. Anticardiolipin antibodies (ACA) are related to LA but appear to be distinct. ACA are detected by solid phase assays (ELISA, RIA) and require a plasma cofactor: beta 2 Glycoprotein-I (beta 2 GPI). ACA and LA activities can be separated in individual patient plasmas by affinity chromatography. In some instances they are of differing isotypes. Preliminary evaluation of beta 2 GPI in coagulation assays suggests it may function as a cofactor for LA activity. Recent work also suggests human prothrombin may represent a necessary cofactor for in vitro LA activity. Paradoxically, patients with LA/ACA may sustain thromboembolic events involving both venous and arterial sites. The prothrombotic properties of LA/ACA have not been satisfactorily characterized. A number of proposals have been reported, including inhibition of prostacyclin (PGI2) generation by endothelial cells, decreased activity of the protein C system, impaired fibrinolysis, and inhibition of beta 2GPI. Among these various hypotheses, down regulation of the protein C system appears most plausible. Also, LA/ACA may interfere with the phospholipase A2-phospholipid substrate complex involved in the generation of arachidonic acid from membrane phospholipids.
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PMID:Antiphospholipid antibodies: proposed mechanisms of action. 128 81

Annexin-V (PAP-I, lipocortin-V) acts as a potent anticoagulant in vitro by binding to negatively charged phospholipids with higher affinity than vitamin K-dependent proteins, with a Kd in the 10(-10) M range. The purpose of the present study was to use annexin-V as a probe to assess the catalytic potential of phospholipids in pro- and anti-coagulant reactions in purified systems and at the surface of endothelial cells in culture after stimulation. Procoagulant tissue factor and anticoagulant thrombomodulin activities were compared by using specific two-stage amidolytic assays performed with purified proteins. Procoagulant activity was estimated by the generation of Factor Xa by the Factor VII(a)-tissue factor complex. Anticoagulant activity was estimated by the generation of activated protein C by either the thrombin-thrombomodulin complex or Factor Xa. Annexin-V induced a decrease of 70% of thrombomodulin activity when thrombomodulin (5.4-214 nM) was reconstituted into phosphatidylcholine/phosphatidylserine (1:1, mol/mol) vesicles at 37.5 or 75 microM-phospholipid concentration, the apparent Ki being 0.5 microM at 75 microM-lipid. The saturating concentration of annexin-V was dependent on phospholipid concentration, but was independent of the phospholipid/thrombomodulin ratio. By contrast, when thrombomodulin was not reconstituted in vesicles, annexin-V had no effect. At 2 microM, annexin-V totally inhibited the generation of activated protein C by Factor Xa in the presence of 75 microM-lipid, the saturating inhibitory concentration being dependent on phospholipid concentration. At 0.1 microM, annexin-V totally inhibited tissue-factor activity present in crude brain thromboplastin. In the absence of stimulation, human endothelial cells in culture expressed significant thrombomodulin activity and no detectable tissue-factor activity. Basal thrombomodulin activity was only slightly inhibited (less than 15%) by 0.5 microM-annexin-V. Phorbol myristate acetate (PMA) induced the expression of tissue-factor activity and decreased thrombomodulin activity at the endothelial-cell surface. Annexin-V, at a concentration of 16 microM, caused an 80% decrease of tissue-factor activity induced by PMA at 10 ng/ml, whereas it inhibited thrombomodulin activity by only 15% on the same stimulated cells. Our results confirm that annexin-V inhibits, in vitro, procoagulant tissue-factor activity and anticoagulant activities (activation of protein C by the thrombin-thrombomodulin complex and by Factor Xa), through phospholipid-dependent mechanisms.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Use of annexin-V to demonstrate the role of phosphatidylserine exposure in the maintenance of haemostatic balance by endothelial cells. 131 63

Thrombomodulin (TM), the endothelial cell surface receptor for thrombin-mediated activation of protein C and of its anticoagulant system, is involved in maintaining vascular nonthrombogenicity, and depressed TM activity may induce intravascular fibrin formation. TM antigen was previously found by immunohistochemical methods in rabbit glomeruli. We therefore attempted to identify the corresponding TM activity in isolated detergent-solubilized rat and human glomeruli. Like purified lung TM, rat glomeruli extracts accelerated the hydrolysis by activated protein C of the chromogenic substrate S-2238 in the presence of 10 nM thrombin, as determined by spectrophotometry. One mg glomerular protein promoted the formation of 681 +/- 115 nmol activated protein C, the equivalent of the amount generated by 845 ng of purified rabbit TM. TM activity correlated with the protein content of the glomerular extracts (r = 0.94). These extracts prolonged rat plasma activated partial thromboplastin time. Incubation of glomeruli with tumor necrosis factor-alpha (TNF) or E. coli lipopolysaccharide depressed their TM-like activity in a dose and time dependent manner. Incubation with TNF suppressed their anticoagulant activity. In human glomeruli, TM activity was also found at a level which corresponded to their TM antigen content, and was determined by ELISA with mouse monoclonal antibody. These results indicate that measurement of glomerular TM activity might help to clarify the mechanisms of intraglomerular fibrin deposition in renal diseases.
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PMID:Quantification and modulation of thrombomodulin activity in isolated rat and human glomeruli. 131 19

Human blood monocytes (Mo) and monocyte-derived macrophages (M psi) possess cytotoxic effects against tumor cell lines when appropriately stimulated by various biological response modifiers, e.g., gamma interferon (gamma IFN) and muramyltripeptide (MTP). Activated Mo/M psi represent a new tool for the treatment of human malignancies, termed "adoptive cellular immunotherapy". Activated Mo/M psi express tissue factor procoagulant activity (PCA), which is a physiological trigger of blood coagulation. PCA was evaluated in vitro using a modification of the one-stage recalcification clotting time, and hemostatic changes were studied in vivo in cancer patients. Nine patients with peritoneal carcinomatosis were injected intraperitoneally with activated Mo and 11 patients with non-small cell lung carcinomas were infused intravenously with activated M psi. Hemostatic changes were followed using activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), fibrinogen level, antithrombin III (ATIII) and protein C (PC) activities. Fibrinolytic activity was estimated by euglobulin lysis time and assays for plasminogen and fibrin/fibrinogen degradation products (FDP). These assays were performed before and after each autologous infusion and on days 2 and 3. Activated Mo and M psi expressed potent PCA (85.5 +/- 7.5 U/ml for MTP activated Mo and 50 +/- 5.3 U/ml for gamma IFN activated M psi suspensions). In both groups of patients, APTT, PT, and TT underwent no significant variations. There was no significant consumption of ATIII or PC, and fibrinolysis was not activated during the study period. In the group injected intraperitoneally with MTP-activated Mo, fibrinogen showed a significant and progressive increase in relation to the development of an inflammatory reaction, reaching a maximum average value of 6.1 g/l at the end of the therapy with a concomitant increase in FDP levels. This increase was not observed after intravenous therapy with gamma IFN-activated M psi. No patient suffered from hemorrhagic or thrombotic events. In our experience, repeated injections of activated Mo or M psi expressing potent tissue factor PCA did not induce significant in vivo activation of the coagulation system in cancer patients.
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PMID:Hemostatic changes in human adoptive immunotherapy with activated blood monocytes or derived macrophages. 132 42

Recent epidemiologic studies found that there is a strong association of hemostatic factors with ischemic heart disease. The Atherosclerosis Risk in Communities (ARIC) Intraindividual Variability (IIV) Study was conducted to estimate the various components of variation in hemostasis factors measured in the ARIC Study and to estimate the measures of repeatability of these factors. A total of 39 subjects (16 men, 23 women) were studied. Each had blood collected three times, with a 1- to 2-week interval between each visit. The contributions of between-person variability, within-person (biologic) variability, and processing and assay variability were estimated. Then the reliability coefficient R was estimated as the proportion of total variance accounted for by between-person variance. The reliability coefficient can be interpreted as the correlation between measures made at repeat visits. Among the various analytes, the reliability coefficients were quite high for activated partial thromboplastin time and plasma factor VIII (R = 0.92, 0.86, respectively). Low repeatability was obtained for antithrombin III activity and protein C (R = 0.42, 0.56, respectively). The lack of repeatability for these variables derives mostly from the processing (field center and laboratory) variation. Other analytes--fibrinogen, plasma factor VII, and von Willebrand factor--were intermediate in repeatability. In comparing the analyte-specific high-level to low-level groups, no substantial difference of within-person plus method coefficient of variation between the two groups was found for any analyte except for factor VIII, whereas the corresponding variance components for most analytes were higher for the higher analyte level. Reliability coefficients from this ARIC IIV study are generally higher than those found in other studies, and this is related to the relative variations in populations studied and to the time between measurements.
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PMID:Short-term intraindividual variability in hemostasis factors. The ARIC Study. Atherosclerosis Risk in Communities Intraindividual Variability Study. 134 24

1. Guinea-pig blood clots rapidly and the clots retract in glass tubes. The prothrombin time is long and the activated partial thromboplastin time short compared to human. The Russel viper venom time is similar to human. 2. Factors VII and X assay at levels far below and factors V, VIII and XII assay far above human levels. Other coagulation factors (fibrinogen, II, IX, XI, Fletcher and Fitzgerald) assay within or close to the human range. 3. The thromboplastin generation test results for guinea-pigs and humans are similar. 4. Platelets are numerous and small. They aggregate with ADP, arachidonic acid and pig plasma, variably with ristocetin and poorly with bovine collagen or thrombin. On electron microscopy, platelets appear small with many dark granules (dense bodies). There is an open canicular system. Glycogen particles are sparse. Microtubules are occasionally seen, mitochondria are rare and alpha-granules are not readily distinguished from dark granules. 5. Ristocetin cofactor is very low, assaying at < 16% of human (< 0.16 U/ml). 6. Leukocyte counts are variable (6300-17,000 per microliters) and differential counts show neutrophils slightly lower and lymphocytes slightly higher than average human counts. 7. Guinea-pig erythrocyte parameters fall within human ranges. 8. Protein electrophoresis shows total protein and albumin to be slightly lower than human. 9. Antithrombin III, Protein C and alpha 2-antiplasmin assay within the human range and plasminogen at very low levels. 10. Bleeding times are consistently about 4 min.
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PMID:Comparative hematology: studies on guinea-pigs (Cavia porcellus). 135 40

This report describes the development of microplate-based blood coagulation assays. The assays require a kinetic microplate reader to follow changes in absorbance at 405 nm caused by the coagulating plasma. Procedures for performing prothrombin time and activated partial thromboplastin time tests are described with intra- and inter-assay variability of a few percentage points. The prothrombin time of normal plasma was 64.5 +/- 3.6 s, and the activated partial thromboplastin time was 69.8 +/- 3.2 s. Clotting times were prolonged when normal plasma was mixed with plasmas deficient in particular coagulation factors, as expected. These assays take advantage of the microplate format (small sample size and multiple simultaneous assays) and can be customized for specific purposes, such as quantifying purified factor IX or assessing protein C activity in plasma.
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PMID:Microplate coagulation assays. 138 75

Selected coagulation and fibrinolytic parameters were assessed in 40 insulin dependent diabetes mellitus patients with varying degrees of metabolic control; 30 healthy subjects matched for age and sex formed the control group. Activated Partial Thromboplastin Time, Prothrombin Time, Fibrinogen, Factor VII, Antithrombin III, Protein C, Plasminogen, alpha 2-Plasmin Inhibitor, Plasminogen Activator Inhibitor-1, tissue-Plasminogen Activator were functionally evaluated. Antigenic levels of tissue-Plasminogen Activator, Thrombin-Antithrombin complexes and fibrinolytic specific product B beta 15-42 were also determined. Compared to the control group diabetic patients displayed significantly higher levels of Fibrinogen (p < 0.01), Factor VII (p < 0.01), Thrombin-Antithrombin complexes (p < 0.01) and Plasminogen Activator Inhibitor-1 activity (p < 0.01). Regardless of the normal level of the tissue-Plasminogen Activator-related antigen, diabetic patients had tissue-Plasminogen Activator activity lower than the control group (p < 0.05). Coagulation Factor VII and Thrombin-Antithrombin complexes were increased only in the patients with poor metabolic control (p < 0.01). Activated Partial Thromboplastin Time, Prothrombin Time, Antithrombin III, Protein C, Plasminogen, alpha 2-Plasmin Inhibitor, B beta 15-42 fibrin peptide were found to be in the normal range. Fibrinogen correlated positively with fasting blood glucose (p < 0.05) and Thrombin-Antithrombin complexes with glycosylated haemoglobin (p < 0.05), whereas Factor VII was positively correlated with glycemia (p < 0.01) and glycosylated haemoglobin (p < 0.05). Higher levels of Fibrinogen were found in patients affected by nephropathy (p < 0.005) or neuropathy (p < 0.05). These results demonstrate an impairment of the haemostatic balance in diabetic patients, that is a possible hypercoagulable state, which represents an important factor in the pathogenesis of atherosclerotic complications.
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PMID:Coagulation and fibrinolytic system impairment in insulin dependent diabetes mellitus. 144 May 30


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