Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pathogenesis of diabetic vasculopathy has been related to modifications in hemostasis and fibrinolysis. 50 non insulin dependent diabetes mellitus patients have been studied. Euglobulin clot lysis time, fibrin plate, tissue plasminogen activator (t-PA) antigen, plasminogen activator inhibitor (PAI) activity, Protein C and S, cholesterol, triglycerides and Hb A1c were determined in blood samples. Diabetic patients showed decreased fibrinolytic activity, as measured by ECLT, with clearly increased PAI levels. Fibrinolytic response to venous occlusion was lower than normal. Vascular complications were associated both with an even higher PAI activity and with a decreased fibrinolytic response to venous occlusion. Elevated PAI activity and decreased fibrinolytic response to stimulus may contribute to vascular disease in diabetes.
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PMID:Hypofibrinolysis associated with vasculopathy in non insulin dependent diabetes mellitus. 211 76

The effect of human activated protein C (APC) on fibrinolysis was studied in a cell-free system by continuously monitoring the thrombin-induced formation and subsequent tissue-type plasminogen activator-induced degradation of fibrin. In systems comprising dialyzed human plasma, APC shortens the time for lysis to occur in a concentration-dependent, saturable manner. Half-maximal activity occurs at an APC concentration of 10 nM. The effect is mediated by enhanced plasminogen activation and is dependent upon ionized calcium. The effect is lost when plasma adsorbed with barium citrate is utilized in place of unadsorbed plasma. The effect can be reconstituted, however, from components recovered from the barium citrate precipitate. Fractionation of the barium citrate adsorbable proteins with polyethylene glycol (PEG) provides two fractions, one of which is obtained by precipitation at 5% PEG, and the other of which is obtained from the 5% PEG supernatant by further precipitation at 40% PEG. The latter fraction contains Factor X and presumably the other vitamin K-dependent clotting factors. Both of these fractions together, but neither of them alone, fully reconstitute barium-adsorbed plasma, such that APC-enhanced fibrinolysis occurs as in non-adsorbed plasma. These fractions also are sufficient to provide for an APC effect in a system in which purified plasminogen and fibrinogen are used in place of barium citrate-adsorbed plasma. Thus, an effect of APC on tissue-type plasminogen activator-induced fibrinolysis exists which is Ca2(+)-dependent and requires two or more, as yet unidentified, components that can be precipitated from human plasma by barium citrate.
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PMID:The activated protein C-mediated enhancement of tissue-type plasminogen activator-induced fibrinolysis in a cell-free system. 212 Feb 9

Recent advances in the understanding of blood coagulation provide strong evidence that exposure of tissue factor is the "match" which initiates blood coagulation. A novel plasma protease inhibitor, called EPI or LACI, effectively extinguishes this "match," leaving Factors IXa, VIII, X, V, and II to function as a "fuse." Activated Factors IX, X, and II are controlled by heparin-enhancable protease inhibitors. Activated Factors VIII and V are destroyed by the protein C/S system. Fibrinolysis is largely cell-based and controlled by differential secretion of plasminogen activators and plasminogen activator inhibitors.
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PMID:Blood coagulation and fibrinolysis: an overview. 219 14

The concept of the haemostatic balance was reviewed, and its potential role in the regulation of tissue repair and the pathogenesis of thrombotic processes was surveyed. Physiological activation of coagulation appears to be dominated by effects of degenerated and injured cells of the vascular wall causing local release of thromboplastin and exposition of activating surfaces. Inhibition of coagulation impairs its progression and the non-thrombogenic nature of the normal endothelium is chiefly caused by the binding of inhibitory components (antithrombin-III, protein C) to specific receptor sites. Physiological activation of fibrinolysis appears to be triggered by and limited to the fibrin because of a specific affinity to fibrin of plasminogen and plasminogen activators. Systemic activation of fibrinolysis is prevented by primary (alpha 2-antiplasmin) and secondary (alpha 2-macroglobulin, alpha 1-antitrypsin) plasmin inhibitors. A plasminogen binding protein (histidine-rich glycoprotein), plasmin inhibitors and activator inhibitors appear to contribute to the regulation of the initial phase of fibrinolysis. A deviation from normal of the dynamic balance, regulating fibrin formation and resolution, may lead to a haemorrhagic and/or a thrombophilic state. Described were the optimization of selected methods for assessment of variables involved in the haemostatic balance. An overestimation of plasminogen concentrations in plasma may occur in patients with elevated levels of fibrinogen or fibrin degradation products, when using assays based on the activation of plasminogen by streptokinase followed by the hydrolysis of a synthetic chromogenic substrate. This source of error could be eliminated by presence of fibrinogen in excess in the plasminogen assay, thereby securing maximum stimulation of the plasminogen-streptokinase complex. The presence of cryoglobulin in plasma interferes with the assessment in euglobulins of plasminogen activator activities. Experiments indicate that tissue-type plasminogen activator adsorb cryoglobulins and that a cold-promoted activation of the factor XII-dependent proactivator system of fibrinolysis is related to the presence of cryoglobulins. Experiments supported the existence of an as yet not characterized factor XII-dependent proactivator. Strictly optimized procedures for the preparation of euglobulins for the accurate determination of plasminogen activators were recommended. The determination of plasminogen activator inhibition in plasma was optimized and simplified. The amidolytic assay of antithrombin-III was shown to be influenced by adsorption to laboratory utensils and aggregation of thrombin. This error could be corrected by protection with additives (Tween 80, polyethyleneglycol 6,000), which also improved the solubility of the chromogenic substrates in aqueous media. The role of thrombosis in myocardial infarction was reviewed.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The haemostatic balance in groups of thrombosis-prone patients. With particular reference to fibrinolysis in patients with myocardial infarction. 219 35

Hemostatic abnormalities are present in a majority of patients with metastatic cancer. These abnormalities can be categorized as 1) increased platelet aggregation and activation, 2) abnormal activation of coagulation cascade, 3) release of plasminogen activator, and 4) decreased hepatic synthesis of anticoagulant proteins like Protein C and antithrombin III. The abnormal activation of coagulation cascade is mediated through release of Tissue Factor, Factor X activators, and other miscellaneous procoagulants from the plasma membrane vesicles of tumor cells. Macrophages of a tumor-bearing host also produce increased amounts of Tissue Factor. Production of Factor X activators and macrophage Tissue Factor is decreased by warfarin. The ability of the tumor cells to produce platelet-aggregating activity and plasminogen activator parallels their metastatic potential in animal and experimental systems. These studies also show that antiplatelet agents and antibodies against plasminogen activator can suppress the metastatic process. One or more laboratory abnormalities of hemostasis can be shown in up to 95% of patients with metastatic cancer. These abnormalities, however, are unable to predict subsequent development of thromboembolic or hemorrhagic complications. Clinical complications occur in 9-15% of the patients in the form of thrombotic or hemorrhagic disorders. The therapy of tumor-related coagulopathy should be guided by its clinical expression. Subclinical DIC should not be treated. Coumadin is generally ineffective for therapy of thrombosis in cancer patients. There is no consensus regarding the use of heparin in acute promyelocytic leukemia (APL). The defibrination in APL may be from disseminated intravascular coagulation as well as systemic fibrinolysis, as shown by decreased alpha 2 antiplasmin levels. In such cases, epsilon aminocaproic acid plus heparin therapy may be of benefit.
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PMID:Hemostasis in malignancy. 174 46

Although Virchow postulated 100 years ago that hypercoagulability states exist, it has only been in recent years that methods of documenting hypercoagulability have been developed. These clotting tendencies can be acquired or congenital. The common causes of acquired clotting tendencies include conditions which result in tissue and cellular damage, shock, transfusion reactions, and tissue necrosis. Certain drugs and drug reactions, and certain disease states which include blood dyscrasias and cancer are also associated with clotting problems. In certain diseases such as homocystinuria, hyperlipidemia, and lupus erythematosus, abnormal clotting tendencies may also develop. Important advances in the recognition of hypercoagulability have come with the documentation that congenital clotting abnormalities exist. Moreover, these abnormalities are proving to be more common than are congenital bleeding syndromes. Patients who appear to have spontaneous clotting manifestations and are under 40 years of age should be screened for one of these abnormalities. These congenital clotting tendencies can be classified as defects in thrombosis inhibitors, dysfibrinogenemias, or defects in fibrinolysis. The first thrombotic inhibitor defect recognized was antithrombin III deficiency which was reported in 1965. Subsequently, Protein C, Protein S, and Heparin cofactor II deficiencies have been recognized as contributing to thrombotic tendencies. Dysfibrinogenemias are relatively rare and most are associated with bleeding problems; however, 11% of the abnormal fibrinogens are associated with a clotting tendency. The reason appears to be that these fibrins are resistant to fibrinolysis. The most common defects which are associated with thrombotic tendencies appear, at the present time, to be due to defects in fibrinolysis. These include hypoplasminogenemia, decreases in plasminogen activator, increases in plasminogen activator inhibitor, and Factor XII deficiency.
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PMID:Acquired and congenital clotting syndromes. 223 69

Parameters of the fibrinolytic system were studied in a primate model where the generation of thrombin was promoted in vivo. The procoagulant stimulus used was a combination of human factor Xa in combination with phosphatidylcholine/phosphatidylserine lipid vesicles (PCPS) as the source of coagulant active phospholipid. The dosage of each component was formulated to provide a gradation of thrombin generating potential assessed prior to in vivo study in an in vitro clotting assay. These ranged from 25.25-36.60 pMole/kg (factor Xa) and 18.85-56.30 nMole/kg (PCPS). In each case, the ratio of the dose of factor Xa/PCPS was maintained at 0.65 (pMole factor Xa/nMole PCPS). Individual dosage combinations producing recalcification clotting times in vitro of 15, 20, 25 and 30 s were used in detailed in vivo studies. Previous studies in dogs had confirmed the thrombin generating potential of factor Xa/PCPS infusions and demonstrated an associated activation of protein C and increased fibrinolytic activity. This has now been extensively characterized in the chimpanzee as follows: 10 min after the infusion of the highest dose (36.6 pMole factor Xa/56.3 nMole PCPS kg bodyweight), the level of circulating t-PA had risen to 900 ng/ml (antigen), 885 IU/ml (functional). Dosage was observed with the lowest dose of 12.25 pMole factor Xa and 18.85 nMole PCPS being associated with relatively minor increases in circulating t-PA activity. There were no changes in u-PA at any dosage during the full time course of the experimental period (90 min). Plasminogen activation was also apparent with alpha-2 antiplasmin levels falling to 30-40% of pre-infusion levels at the highest dosages.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The fibrinolytic potential of the normal primate following the generation of thrombin in vivo. 240 50

Defibrotide is a derivative of polydeoxyribonucleotide extracted from bovine lung. Defibrotide has been found to modulate endothelial cell function causing increase in t-PA production and release with correction the defect in Cuff test in vascular disorders. Defibrotide causes a significant elevation in the PGI2 formation. In addition increase of platelet c-AMP levels with a decrease of MDA and TXA2 formation has been shown in human subjects. Defibrotide causes an inhibition of platelet activation were demonstrated with surface activation method as well ultrastructurally. Besides, an increase of protein C and FV were observed, a synergic action with heparin was observed. A strong antithrombotic effect has been shown in animal models and unlike most antithrombotic drugs defibrotide did not cause any effect of clotting tests in animals and human subjects. All findings support our earlier suggestion that defibrotide mainly acts via the modulation of endothelial cell function and acts as a novel fashion in contrast to the other drugs used in this area.
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PMID:Clinical pharmacology and mode of action of a new antithrombotic compound: Defibrotide. 245 16

A series of coagulation tests is described by which an increased thrombotic tendency is likely to be detected. These tests were carried out in 268 patients with venous thromboembolic disease and in 583 patients with arterial thrombotic manifestations. In venous thromboembolism alterations which point to hypercoagulability were found in 50% of all cases. Most frequent findings were a diminished availability of t-PA followed by low levels of Protein C, AT III and of Heparin cofactor II. In arterial thrombotic disease alterations of the clotting system were found in 77% of the patients. There was a high frequency of increased spontaneous platelet aggregation, of a diminished t-PA availability and of a combination of both alterations. Other abnormal results were rare with the exception of a diminished Heparin cofactor II which was found in 3% of the patients. The consequences which arise for prophylaxis and therapy when the defect is known are discussed.
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PMID:New diagnostic possibilities for the detection of thrombophilic states. 246 11

Nine patients with, and 11 without, venous thromboses (DVT) from two families were studied. In family 1, four members with, and one without, DVT had t-PA activity below the lower limit of the controls (21.3 IU/ml, n = 19) after 20 min venous occlusion (VO). After VO t-PA antigen (t-PA:Ag) was below the lowest value of the controls (22.8 ng/ml) in all five cases with low t-PA activity. All the family members, both with and without thrombosis, had normal t-PA inhibitor activities (PAI). In family 2 t-PA activity after VO was low in three symptomatic and four asymptomatic family members. t-PA:Ag was also low in four of these. PAI level was normal in all but one family member. Mild type I von Willebrand's disease was discovered in four members of family 2. Deficient t-PA:Ag response was found in two of these. Antithrombin III, protein C and protein S were normal in both families. It is concluded that low fibrinolytic capacity, independent of PAI, is associated with familial DVT. Our data suggests autosomal dominant inheritance.
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PMID:Familial hypofibrinolysis and venous thrombosis. 249 18


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