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)

As in adults, desmopressin (DDAVP) can be used in children for prophylaxis of bleeding and to stop bleeding in many hereditary and acquired bleeding disorders. DDAVP is the treatment of choice in children with mild hemophilia and type 1 von Willebrand's disease (vWD). It is effective in some variants of vWD and in many patients with platelet function defects. It reduces the bleeding diathesis of children with uremia and drug-induced bleeding complications. In any case, a test dose of DDAVP has to be given to the patient to predict the hemostatic effect before relying on this drug for treatment. The response can be measured by shortening of the bleeding time (BT) and of partial thromboplastin time (PTT), indicating a rise of Factor (F) VIII or von Willebrand factor (vWF). Side effects such as facial flushing, transient headache, increased pulse rate, and drop in systolic blood pressure are mild and transient. They can be minimized when the dose is not exceeding 0.3 microg/kg body weight, and the infusion lasts at least 20 to 30 minutes. The strong antidiuretic action of DDAVP has some potential problems that are negligible in adults and older children when water intake is restricted. In infants and small children under the age of 18 months, however, DDAVP should be used with caution and with close surveillance in order to prevent water intoxication and electrolyte imbalance. The danger is increased when the patients receive parenteral fluid substitution. The advantages of DDAVP include the reduction in the use of plasma factor concentrates, thereby minimizing the danger of immunological or infectious complications, as well as the considerable reduction of costs realized by treatment with this form of medication. Fortunately, it can be applied successfully in the most frequent hereditary bleeding disorder, namely vWD type 1.
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PMID:Desmopressin (DDAVP) in bleeding disorders of childhood. 1006 51

The von Willebrand's Disease affects about 1-3% of the population and it is undiagnosed in most people. Originally described by the Finish physician Erik von Willebrand in 1926 this disorder is associated with mucous membrane bleeding including epistaxis, hypermenorhoea and excessive bleeding from surgery and dental procedures. In von Willebrands disease the patients have a quantitative or qualitative abnormality in the von Willebrand Factor (vWF) which has two major functions: it serves by bridging between platelets and injury site in the blood vessel wall, and it circulates as a complex with factor VIII, protecting it from rapid degradation. More than 20 different types and subtypes of vWD have been described but almost all patients can be classified as having 1 of the 2 most common types of vWD. About 70% of patients have type 1 and about 10-20% present themself with type 2A and 2B vWD type 3 in about 10%. By taking a clinical history of bleeding it is important to think about vWD and to make the appropriate diagnosis. If the vWD is suspected diagnostic tests should include an activated partial thromboplastin time, bleeding time, factor VIII:C, Ristocetin cofactor, and vWF antigen. Additional testing of ristocetin induced plattlet adhesion (RIPA), the multimeric structure and collagen binding test and genanalysis allow diagnosing the different types of v. Willebrand Disease. The treatment of choice in mild forms is the synthetic agent desmopressin. In patients with severe type 1, type 2B, 2N and type 3 or in people who do not response to desmopressin, the appropriate treatment is a factor VIII concentrate that is rich of vWF. Until now no recommendations in the orthopaedic literature have been found regarding diagnosis and treatment of vWS patients. Based on the experience with 43 orthopaedic patients presenting vWD over the last 15 years a contemporary guideline for the successful perioperative management of vWD in orthopaedic surgery is presented. In a close collaboration between the orthopaedic surgeon and the specialized haemostaseologist every invasive procedure in patients with vWD can be undertaken without the risk of excessive bleeding.
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PMID:[Prevalence, pathophysiology, diagnosis and treatment of von Willebrand syndrome in orthopedic trauma patients]. 1033 31

Prothrombin time (PT) and activated partial thromboplastin time (APTT), popularized as a routine assay for screening blood coagulation disorders and monitoring anticoagulant therapy, still involve some issues regarding standardization. In this lecture, we present propositions to resolve these problems in respective laboratory. Although international normalized ratio (INR) calculated by international sensitivity index (ISI) of PT reagent seems to improve discrepancy of sensitivity between reagents, local calibration of sensitivity of PT reagent in respective laboratories (local SI) is reasonable to make INR/ISI system more useful. However, local calibration of reagent is not easy by WHO recommended method in a small size laboratory. By using AK calibrant (IMMUNO AG), one of calibration plasma for INR, we investigated its possibility to calibrate local SI in four different reagents, compared with the recommended methodology. The results led the following process to determine reagent and calibrate local SI for practical use of INR/ISI system. (a) Use PT reagent of which ISI is close to 1.0 if possible, and utilize manufacture's ISI as is for INR. (b) Select PT reagent labeled specific ISI for an instrument as the same as used in the lab., and use the manufacture's ISI as is, if impossible to choose small ISI reagent. (c) If use a reagent of which ISI is close to 2.0 and shown no specific ISI for used detector, adjustment of local SI by commercial calibration plasma is recommended when unavailable warfarinized patient plasma. In APTT, we attempted to evaluate sensitivity between five different APTT reagents with a patient model by hemophilia A plasma contained various FVIII: C. This model reflected difference of sensitivity between reagents in results. Because standardization of APTT is not improved in this point, certification of APTT pattern in each laboratories with patient models is required for not only monitoring of heparinization, but also screening of typical coagulation disorders such as hemophilia and von Willebrand disease.
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PMID:[Suggestions and propositions to resolve some issues for standardization of prothrombin time and activated partial thromboplastin time]. 1037 64

By virtue of a severely prolonged aPTT with a normal thromboplastin time (prothrombin time) and a normal thrombin time, severe FXII deficiency has been diagnosed in a woman without a bleeding diathesis or a history of thromboembolic complications. A deficiency of a factor of the contact activation system (FXII, prekallikrein, high molecular weight kininogen) is usually diagnosed during routine coagulation tests demonstrating a prolonged aPTT. The severe and partial deficiency of FXII, of prekallikrein or high molecular weight kininogen is not associated with a bleeding tendency. In contrast, severely factor XI deficient subjects may suffer from a mild hemorrhagic diathesis, whereas FVIII deficiency (hemophilia A, autoimmune "hemophilia", von Willebrand disease) and FIX deficiency (hemophilia B) are associated with a bleeding tendency of varying severity, depending on the clotting activity of FVIII or FIX, respectively. An isolated prolongation of the aPTT due to a lupus anticoagulant, however, is frequently associated with arterial and/or venous thrombosis. Therefore, in case of a prolongation of the aPTT, its cause has to be determined.
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PMID:[A patient with isolated prolongation of aPTT without hemorrhagic diathesis anamnesis: severe, hereditary factor XII deficiency]. 1051 21

There are three different aspects in the etiological diagnosis of hemostasis disorders: (1) primary hemostasis evaluation; (2) coagulation evaluation; and, (3) thrombosis evaluation. In every case, a look at the medical history is an essential step before proceeding to biological investigations. Bleeding time is the first step of the primary hemostasis evaluation; prolonged drug use (particularly salicylates) and thrombocytopenia must be first considered; only then will the Von Willebrand factor and platelet functions be studied. Coagulation evaluation first requires the study of the overall coagulation tests (Quicks test, partial thromboplastin time test and thrombin time test); determination of the different plasma coagulation factors and search for a circulating anticoagulant will be performed secondarily, allowing differentiation between the different acquired or constitutional coagulation disorders. Thrombosis evaluation must first consider a local or general inciting factor before looking for anti-phospholipid antibodies, an acquired protein C or S deficiency or a constitutional hemostasis disorder.
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PMID:[Exploration of hemostasis disorders in children (excluding the neonatal period)]. 1054 86

Menorrhagia in adolescents may be the presenting sign of a systemic hemostatic disorder. The evaluation of adolescents with menorrhagia should include an assessment of the pelvic organs to exclude anatomic pathology, and if none is found the possibility of primary hematological abnormality should be considered. Initially, a thorough personal and family history of a bleeding tendency should be obtained. Thereafter, we suggest a number of basic "screening" clotting assays be performed. These should include a platelet count, prothrombin time, activated partial thromboplastin time, fibrinogen level and bleeding time. Abnormalities of any of these tests should then be further investigated using more specific clotting assays. The most common disorders reported to cause menorrhagia in adolescents are von Willebrand's disease, factor XI deficiency, and Glanzmann's thrombasthenia. General and specific therapeutic measures for treating these disorders are discussed.
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PMID:Abnormal vaginal bleeding in adolescence as the presenting symptom of a bleeding diathesis. 1054 3

The most powerful instrument to establish the presence or absence of a coagulation disorder is the history of the patient. In addition, screening laboratory tests (consisting of the platelet count, bleeding time and global clotting assays, such as the prothrombin time and the activated partial thromboplastin time) may be helpful to support the diagnosis. In two patients, a 21-year-old man and a 10-year-old girl, with a marked history of enhanced bleeding normal screening laboratory tests were found. The male patient had a congenital alpha 2-antiplasmin deficiency and the girl had a homozygous deficiency of factor XIII. Some defects in the coagulation system (such as defects in fibrin network formation and fibrinolysis, but also mild Von Willebrand disease) are indeed not detected by screening laboratory tests. In patients with a strong suspicion of a coagulation disorder such defects should be specifically tested for.
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PMID:[Blind spots of the diagnostic hemostasis screen]. 1072 52

Valproic acid is commonly used in the management of childhood epilepsy. The known hematologic side effects of the drug are hemorrhagic diatheses, thrombocytopenia, and hypofibrinogenemia. We studied coagulation parameters in 29 epileptic children receiving valproic acid for at least 6 months. Their ages ranged between 2 and 18 years (10.2 +/- 4.9 years). The total valproic acid dose was 250 to 1000 mg/day equivalent to 20 to 30 mg/kg/day. Treatment duration ranged from 6 to 57 months. These children had not previously had a hemostatic defect and had no family history of bleeding disorders. Platelet count, prothrombin time, activated partial thromboplastin time, bleeding time, fibrinogen, platelet aggregation assays, and ristocetin cofactor activity levels were determined in all of the patients, but von Willebrand's factor antigen levels could be determined in only 14 patients. The values of von Willebrand's factor antigen ranged from 53 to 218% (104.1 +/- 42.3), and ristocetin cofactor activity levels ranged from 11.5 to 218% (94.5 +/- 43.1). Six of the 29 children (20.7%) had decreased values of ristocetin and cofactor activity and were considered to have acquired von Willebrand's disease. The decreases in coagulation parameters were not dependent on either valproic acid dose or treatment duration. Two patients with low ristocetin cofactor activity values had mild epistaxis, which did not require discontinuation of therapy. In patients receiving valproic acid therapy, this side effect must be considered, especially before surgical intervention and serious traumatic conditions.
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PMID:Coagulation abnormalities and acquired von Willebrand's disease type 1 in children receiving valproic acid. 1191 69

Von Willebrand disease (vWD) is caused by quantitative or qualitative defects, or both, of the von Willebrand factor (vWF), a multimeric high-molecular glycoprotein (GP). Typically, it affects the primary hemostatic system, which is reflected by a mucocutaneous bleeding tendency simulating a platelet function defect. The vWF promotes its function in two ways: (1) by supporting platelet adhesion to the injured vessel wall under conditions of high shear forces and (2) by its carrier function for factor VIIIc (FVIIIc) in plasma. Because of the complexity of the disease, diagnosis of vWD is one of the most challenging of any coagulation disorder. The stepwise diagnosis of vWD includes patients and family history, screening procedures (bleeding time [BT], filter tests, platelet counts, activated partial thromboplastin time [aPTT]), confirmatory tests (vWF antigen [vWF:Ag], vWF ristocetin cofactor activity [vWF:RCo], vWF collagen-binding [vWF:CB] assay, ristocetin-induced platelet aggregation [RIPA], FVIIIc) and tests for final classification (multimeric analysis, FVIII binding capacity of vWF [vWF:FVIIIB], platelet vWF). In 1999, we classified 303 patients with congenital vWD as type 1 (n = 122), type 2 (n = 171), and type 3 (n = 10). Type 2 was further subdivided into type 2A (n = 126), type 2B (n = 17), type 2M (n = 22), and type 2N (n = 6). Type 2A showed a remarkable heterogeneity, with only 27.8% (n = 36) of the "classic" IIA pattern. The other high-frequency patterns were type IB (25.4% n = 32) and type IIE/F/H-like structural abnormalities (28.6% n = 36). The spectrum was completed with samples from patients with types 2D, 2C, 2C Miami, smeary structures, and other rare subtypes (together 18.9% n = 23).
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PMID:Laboratory diagnosis of congenital von Willebrand disease. 1199 41

Fourteen patients with different types of von Willebrand disease (vWD) having acute bleeds or elective surgery were treated with Immunate(sound recording copyright sign), a double-virus inactivated factor VIII/von Willebrand factor (FVIII/vWF) concentrate. The concentrate was applied as a bolus or via continuous infusion. FVIII activity (FVIIIc), vWF antigen (vWF:Ag), ristocetin cofactor activity (vWF:RCo), collagen binding activity (vWF:CB), activated partial thromboplastin time (aPTT), and von Willebrand multimers (vW-multimers) were monitored for 48 hours. Pharmacokinetic analyses were performed. The clinical efficacy was rated excellent or good. Bleeding complications occurred in 3 patients due to an additional FXIII deficiency in one patient, to a surgically induced bleed in another patient, and a rather short substitution period in the third patient. There were no serious adverse experiences. One patient showed a phlebitic reaction at the site of venous access after more than 100 hours of continuous infusion, requiring a change to application via bolus.
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PMID:Successful treatment of patients with von Willebrand disease using a high-purity double-virus inactivated factor VIII/von Willebrand factor concentrate (Immunate). 1199 43


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