Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.6 (thromboplastin)
13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Coagulation factors evaluated in a group of patients with borderline hypertension. The following tests were carried out: prothrombin time (PT) and partial thromboplastin time (PTT), Factor VIII coagulant activity, Factor VIII antigen and Factor VIII ristocetin cofactor, Factor XII and Factor XI activities. These tests were selected for their relationship to the contact coagulative activation near the vascular wall. Comparing the results with those of normal controls, Factor VIII coagulant activity, Factor XII and PTT levels were significantly higher. Other tests were all within normal limits in both groups. High Factor VIII and Factor XII levels associated with PTT shortening suggest that an increased synthesis and/or release of these coagulation factors was present in our patients. Activated coagulation seems to be present in borderline hypertension before the appearance of clinical signs of vascular lesions.
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PMID:Clotting changes in borderline hypertension. 350 21

Effect of urinary enzyme inhibitor urinastatin (MTI) on disseminated intravascular coagulation (DIC) was investigated. The prolongation of PTT and increase in FDP in endotoxin-induced DIC in rats were restored by the intravenous infusion of MTI. The reduction in platelet counts, decrease in fibrinogen level and prolongation of PT were partially suppressed by the drug. Furthermore, in vitro addition of MTI prevented the decrease in r and k values and increase in ma and m epsilon values in the thromboelastogram of whole blood in endotoxin-induced DIC in rabbits. It is suggested that MTI might prevent DIC in vivo and in vitro through the inhibition of Factor XII activity and through the prevention of thromboplastin release caused by endotoxin.
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PMID:[Effect of urinastatin on disseminated intravascular coagulation]. 379 58

Cholesterol sulfate was found to display a strong ability to trigger the activation of Factor XII and prekallikrein in the presence of HMW kininogen. Other sulfate ester derivatives of testosterone, estrone, pregnenolone and dehydroepiandrosterone and cholesterol tested did not show any effect on the activation of Factor XII and prekallikrein. The activity of cholesterol acetate and sulfodeoxycholic acid was very weak. Cholesterol sulfate markedly shortened the partial thromboplastin time of normal human plasma, but not plasmas deficient in Factor XII, Factor XI and HMW kininogen. Upon prolonged incubation, the partial thromboplastin time of prekallikrein-deficient plasma was also shortened. Moreover, as well as kaolin and sulfatide, cholesterol sulfate shortened the partial thromboplastin time of plasmas from monkey, dog, rat, guinea pig, sheep, cow, hog and horse, but not from duck and chicken. Since cholesterol sulfate is distributed in erythrocytes, various organs and body fluids, it may play an important role in the activation of the intrinsic blood coagulation system.
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PMID:Activation of factor XII and prekallikrein with cholesterol sulfate. 384 26

Intravenous administration of hematin is effective in the treatment of acute exacerbations of the inducible porphyrias. In the course of such treatment, coagulopathies have occurred that are characterized by prolongation of prothrombin time, partial thromboplastin time, and formation of fibrin split products. In experiments in vitro with normal human plasma, we observed that hematin and protoporphyrin activated Factor XII-dependent pathways of coagulation and fibrinolysis, and that they generated kallikrein activity. Incubation of protoporphyrin with purified Factor XII resulted in activation as measured by amidolysis of a chromogenic substrate. Neither coproporphyrin, uroporphyrin, delta-aminolevulinic acid, porphobilinogen, or bilirubin activated Factor XII-dependent pathways. Exposure of serum containing added uroporphyrin, coproporphyrin, and protoporphyrin, but not hematin, to ultraviolet light (405 nm) resulted in activation of the classical pathway of the complement system. On the other hand, exposure of plasma containing uroporphyrin or coproporphyrin to ultraviolet light did not result in activation of Factor XII-dependent pathways.
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PMID:Activation of factor XII-dependent pathways in human plasma by hematin and protoporphyrin. 403 Oct 58

Interaction of normal and coagulation factor deficient bloods with glass, Teflon and silicone-coated glass surfaces have been studied. The morphology of the blood-surface interaction was observed by scanning electron microscopy. Activation of the intrinsic coagulation system and progression of these changes, monitored by use of the partial thromboplastin time test, were influenced by both the type of surface to which blood was exposed and the deficiencies of coagulation Factors I, VIII, IX, or XII. Deficiency of fibrinogen appears to enhance, minimally, activation of the coagulation sequences by test materials. However, deficiency of fibrinogen markedly reduces adhesion of platelets to foreign surfaces. Deficiency of Factor XII, but not of Factors VIII or IX, decreases platelet adhesion to nonbiologic surfaces but to a lesser extent than does deficiency of fibrinogen. Roughness of test surfaces appears to encourage cellular deposition from blood. An ex vivo model designed for screening materials for their compatibility with blood is described.
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PMID:Reactions of blood with nonbiologic surfaces. Ultrastructural and clotting studies with normal and coagulation factor deficient bloods. 463 36

A prolonged partial thromboplastin time in a patient was investigated, as well as those of his family members. One sibling, the mother, and the patient all shared a lupus-like anticoagulant and low Factor XII levels in association with the A 11, Bw 35, DR 4 haplotype previously found in familial lupus erythematosis. The rest of the family had normal coagulation profiles and the entire family had normal findings when tested for ANA, complement and immune complexes. After being confirmed in a second coagulation laboratory, the lupus-like anticoagulants in the three affected members of the family disappeared upon retesting 3-8 weeks later.
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PMID:Transient appearance of the lupus anticoagulant in three family members sharing the A11B35DR4 haplotype. 641 25

Low amount of sulfatides initiated intrinsic coagulation and the appearance of kallikrein activity in normal human plasma. The initiation of procoagulant and kallikrein amidolytic activity was dependent on the presence of Factorr XII, high molecular weight kininogen and prekallikrein. Because the activated partial thromboplastin clotting times in prekallikrein deficient plasma approach normal values upon prolonged incubation with kaolin, this phenomenon was studied and found to be even more pronounced in the presence of sulfatides. Shortening of the clotting time was essentially completed in 5 min in the presence of sulfatides whereas a pre-incubation of 15 to 20 min was required in the presence of kaolin. The limited proteolysis of 125I-Factor XII in plasma during incubation was more rapid and more extensive in the presence of sulfatides than in the presence of kaolin. Factor XII cleavage in prekallikrein deficient plasma was completed in less than 5 min in the presence of sulfatides and in less than 15 min in the presence of kaolin. Thus, the appearance of Factor XII-dependent coagulant activity correlates with the limited proteolysis of Facto XII when normal or prekallikrein deficient plasma is activated by sulfatides or by kaolin. These observations are consistent with the hypothesis that Factor XII is cleaved in plasma to generate maximal Factor XIIa activity.
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PMID:Initiation of contact activation by sulfatides. 660 64

Clotting tests based upon the activated partial thromboplastin time are disturbed by heparin. This brief communication shows that Factor XII clotting activity in plasma samples heparinized in vitro and in vivo can be measured accurately by means of an aPTT-test using congenitally deficient substrate plasma when the plasma dilution buffer contains hexadimethrine bromide (Polybrene), 15 mg/L. This method of neutralizing heparin obviates more complicated procedures such as heparin adsorption to anion exchange resins.
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PMID:Assay of Factor XII clotting activity in heparinized plasma. 662 10

Fujiwara trait, the first case of kininogen deficiency in Japan previously reported which did not show any clinical symptom except the prolonged activated partial thromboplastin time was further examined. The activated partial thromboplastin time of the patient was corrected by addition of normal, Factor XII deficient or Fletcher plasma, but not corrected by Fitzgerald or Williams plasma. It was also corrected by addition of highly purified bovine or human high molecular weight (HMW) kininogen, but not by low molecular weight (LMW) kininogen. When total kininogen was measured as the amount of bradykinin released by trypsin, only a trace amount was detected in Fujiwara as well as Williams plasma. No immunoreactive protein against anti-human-HMW-kininogen nor anti-human-LMW-kininogen was found in Fujiwara plasma. Acetone-kaolin-activated plasma kallikrein was not generated by Fujiwara plasma. Substitution with normal plasma in various ratios showed the generation of various plasma kallikrein activities. Calculations with these activities of mixed plasma gave the prekallikrein content of Fujiwara trait plasma about 30% of the normal level. These results suggest that Fujiwara trait is very similar to Williams trait in that both plasmas were deficient in HMW and LMW kininogens with reduced content of prekallikrein.
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PMID:Abnormalities in the contact activation through factor XII in Fujiwara trait: a deficiency in both high and low molecular weight kininogens with low level of prekallikrein. 678 99

A case of cross-reacting material-negative Fletcher trait with additional partial deficiency of Hageman factor (HF, Factor XII) is described. Although the patient presented with a recent history of frequent epistaxis, he had no other personal or family history of a tendency toward bleeding or infection. Similar to other cases of Fletcher trait, his plasma showed a markedly prolonged partial thromboplastin time which could be corrected by prolonged incubation with the surface-activator kaolin. Surface-induced fibrinolysis, amidolysis of alpha-N-benzoyl-proline-L-phenylalanine-L-arginine-p-nitroanilide, and cold-promoted enhancement of factor VII activity, reactions requiring the presence in the plasma of fletcher factor (prekallikrein), in addition to Hageman factor and Fitzgerald factor (high-molecular weight kininogen), were also defective. In vivo chemotaxis of polymorphonuclear leukocytes and monocytes (Rebuck's skin window technique) in response to skin abrasions was defective, but was normal when diphtheria-tetanus toxoid was also applied. In vitro leukocyte chemotaxis (Boyden chamber technique) in response to normal or patient's own serum activated with zymosan was normal. Together with previous observations that kallikrein generated chemotactic activity, possibly via activation of C5, the present observations suggest that prekallikrein activation may be important for in vivo leukocyte chemotactic response to skin abrasion. The inheritance of Fletcher trait in this patient is unclear.l Although the father was an apparent heterozygote, the mother was completely normal for Fletcher factor procoagulant activity and antigen. The mild Hageman factor deficiency in the patient did not contribute significantly to the plasma defects described and was likely inherited from the father who had a low HF procoagulant activity.
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PMID:Severe Fletcher factor (plasma prekallikrein) deficiency with partial deficiency of Hageman factor (factor XII): report of a case with observation on in vivo and in vitro leukocyte chemotaxis. 691 94


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