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

---

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

Both the HEPTEST and amidolytic anti factor Xa assays are currently being used for heparin activity detection in plasma from patients receiving standard heparin or low molecular weight heparin (LMWH). In this study we have investigated the influence of recombinant and endogenous Tissue Factor Pathway Inhibitor (TFPI) on these assays. The HEPTEST determinations were performed on an ACL 300 R Clottimer using the APTT program which resulted in a longer incubation time with factor Xa than recommended by the manufacturer. rTFPI added to plasma prolonged the HEPTEST clotting time markedly, but had only a little effect in the amidolytic assay. Antibodies against TFPI (anti-TFPI) abolished these effects. The effect of adding rTFPI and Logiparin was additive. When anti-TFPI IgG was added to samples of normal plasma, a statistically significant shortening of the HEPTEST clotting time was seen. When anti-TFPI was added to plasma samples from volunteers who had received Logiparin by subcutaneous or intravenous injection, then the HEPTEST clotting time was shortened considerably. For some samples the clotting time was halved. These experiments show that the HEPTEST clotting time is prolonged not only by heparin-antithrombin III, but also by TFPI released by heparin injection.
...
PMID:Effect of tissue factor pathway inhibitor (TFPI) in the HEPTEST assay and in an amidolytic anti factor Xa assay for LMW heparin. 133 10

Investigation of a patient with an unexpected prolonged activated partial thromboplastin time showed on repeat testing that the patient had normal coagulation times, but had been preceded on the automated coagulation analyzer run (ACL 300R--Instrumentation Laboratory, Lexington, MA) by a heparin-contaminated apheresis line sample taken from a different patient. Heparin carryover was suspected, and subsequent experiments showed that ex vivo heparinization of normal plasmas will produce similar effects in following normal plasma samples in a test series. This effect increases with the baseline activated partial thromboplastin time and the heparin concentration. It is recommended that coagulation analyzers that are susceptible to carryover be cleaned after testing of plasmas likely to have heparin concentration of more than 5 x 10(3) U/L. Furthermore, when using analyzers of this type, investigation of an unexplained activated partial thromboplastin time must include a review of the preceding samples tested, particularly when duplicate testing has been discontinued.
...
PMID:Clinically significant heparin carryover on the ACL 300R. 151 37

In this study the authors compare two automated coagulation instruments: the koagulab-40A (Orthodiagnostics Systems) and l'ACL-100 (Instrumentation Laboratory) using two different methods of detection, photo-optical and nephelemetric respectively. The three parameters studied are: prothrombin time (PT) (82 samples), activated partial thromboplastin time (APTT) (86 samples) and fibrinogenemia (FIB) (109 samples). For each test, they use two reagents of different origins. Samples come from people without any haemostatic disorder and from patients showing abnormal levels of these parameters (heparins or antivitamins K treatments, hypo or hyperfibrinogenemias). For the tree parameters examined, they obtain coefficients of correlation: 0.94 to 0.99 between the two instruments. These values are not noticeably modified by reagent substitution. For fibrinogenemia, the coefficient of variation (CV) is about 4%. Finally, in comparison with the photooptical classical method, the ACL-100 is more rapid, more economical (reduced volumes of reagents) and more feasible (dilutions of plasmas and tubulure changing are not necessary for fibrinogen).
...
PMID:[Prothrombin time, activated partial thromboplastin time, plasma fibrinogen determination. Comparison of two automated coagulation systems: Koagulab 40-A and ACL-100]. 180 70

Using an ACL 300R coagulometer (Instrumentation Laboratory) we assessed the clinical usefulness of a new method to measure PS activity (PS:Act), based on the prolongation of prothrombin time of a mixture of diluted plasma sample, PS depleted plasma previously incubated with Protac for protein C activation, bovine thromboplastin and calcium ions. The results were compared with those from immunological assays. PS:Act was measured in 42 apparently healthy subjects, in 12 patients with hereditary PS deficiency (HPSD group) diagnosed on the basis of immunologic tests and in 48 patients with episodes of juvenile venous thromboembolism at least three months prior to testing (JVTE group). All the HPSD patients had PS:Act below the normal range (less than 62%). In JVTE group 9 patients (18.7%) showed abnormal results for PS:Act, 4 (8.3%) had low levels of free PS:Ag; all patients had normal total PS:Ag levels. Levels of antiphospholipid antibodies (immunologic test) were normal in the 9 JVTE patients with low PS:Act. When all the results were considered together (n = 102), the correlation coefficient between PS:Act and free PS:Ag was 0.78 (p less than 0.01).
...
PMID:Protein S activity in patients with heredofamilial protein S deficiency and in patients with juvenile venous thrombosis. Results of a functional method. 183

In this paper we report the case of a new Italian family with severe cross-reacting material prekallikrein deficiency (CRM-). The proposita is a 22-year-old woman referred for evaluating an extremely prolonged activated partial thromboplastin time (APTT) detected during a routine screening. No clearcut bleeding history was reported. Prekallikrein antigen and activity were not measurable. The other contact-phase factors were within the normal range. Using an electromechanical coagulometer, six different commercial reagents yielded a markedly prolonged APTT (ratio greater than 2). By prolonging the incubation time up to 10 min, APTT was normalized only with reagents employing ellagic acid as activator. On the contrary, APTT remained markedly prolonged using particulate activators (i.e. micronized silica and celite). No differences were observed using either rabbit or bovine brain cephalin. APTT was also performed on a laser automated ACL instrument; in this case reagents using ellagic acid yielded only moderately prolonged APTT values (ratio 1.3 vs 1.4). The intrinsic fibrinolytic activity, as assessed by blood activator inventory test, was found to be moderately reduced (about 50% of normal) in the proposita, whereas normal values were measured in the heterozygous relatives. After infusion of 0.3 micrograms/kg 1-desamino-8-D-arginine vasopressin (DDAVP), kallikrein levels did not change in the proposita and her heterozygous relatives. A normal release of tissue-plasminogen activator, as assessed by fibrin-plate assay, was observed in all family members including the proposita.
...
PMID:A new Italian family with severe prekallikrein deficiency. Desmopressin-induced fibrinolysis and coagulation changes in homozygous and heterozygous members. 212 71

Two automatic coagulometers, ACL 810 (Instrumentation Laboratory), a laser-nephelometric centrifugal analyzer, and KoaguLab 40 A (Ortho Diagnostics), an optical automatic coagulometer, were compared with the manual tilt-tube method for the performance of activated partial thromboplastin time (APTT). Seven commercial APTT reagents were used for duplicate determinations in 30 normal controls, 26 patients with liver disease, and 33 patients on full-dose heparin treatment. Clotting times were longer with the manual method than with ACL 810 and, to a lesser extent, with KoaguLab 40 A. Average imprecision of duplicate determinations (coefficient of variation [CV]) was less with ACL 810 (less than 1.5%) than with KoaguLab 40 A (2.9%) and the manual method (2.4%). Differences in slope of the regression curves of clotting times obtained with the coagulometers over the tilt-tube method were observed with all the reagents tested (P less than 0.01). Transformation of clotting times of controls, patients with liver disease, and patients on heparin therapy to APTT ratios did not eliminate the bias resulting from the different reagents (P less than 0.001) and clot-detection methods (P less than 0.001); in controls, significant (P less than 0.001) reagent-method interaction was also observed. The in vitro heparin sensitivity differed with the APTT reagents evaluated and was influenced by the clot-detection method used. Transformation of APTT ratios of anticoagulated patients to apparent plasma heparin levels--as derived from in vitro dose-response curves--effectively eliminated the bias resulting from the different clot-detection methods but had no effect on the bias resulting from the different APTT reagents. In vitro heparin activity curves thus have little, if any, relevance for the ex vivo monitoring of heparin treatment.
...
PMID:Effect of clot-detection methods and reagents on activated partial thromboplastin time (APTT). Implications in heparin monitoring by APTT. 239 4

Two automatic coagulometers--ACL 810 (Instrumentation Laboratory), a laser-nephelometric centrifugal analyzer, and KoaguLab 40 A (Ortho Diagnostics), an optical automatic coagulometer--were compared with the manual tilt-tube method for the performance of prothrombin time (PT). Seven ISI- (International Sensitivity Index) calibrated commercial thromboplastin reagents were used for duplicate determinations in 30 normal subjects, 30 patients with liver disease, and 30 patients receiving stabilized oral anticoagulation. Clotting times were longer with the manual method than with ACL 810 and, to a lesser extent, with KoaguLab 40 A. Average imprecision of duplicate determinations (CV) was less than 1% with ACL 810; KoaguLab 40 A and the manual method had similarly higher imprecisions (2.8% and 2.7%). Differences in origin and slope of the regression curves of clotting times obtained with the coagulometers over the tilt-tube method were observed with all the reagents tested. Transformation of clotting times to PT ratios did not eliminate the bias resulting from the different clot-detection methods. A higher percentage of patients with liver disease had abnormal PT ratios when their plasma was tested with the coagulometers than with the manual method. Transformation of PT ratios to International Normalized Ratios effectively eliminated the bias resulting from the different thromboplastin reagents but had no effect on the bias resulting from the different clot-detection methods. A significant proportion of patients appeared excessively anticoagulated (INR greater than 4.5) with the coagulometers but not with the manual method. These results highlight the need for standardization of both instrumentations and reagents to improve monitoring of oral anticoagulant treatment.
...
PMID:Comparison of two automated coagulometers and the manual tilt-tube method for the determination of prothrombin time. 277 51

We compared the concordance and predictive powers of activated partial thromboplastin time (APTT) and of IgG and IgM antibody to cardiolipin (aCL), for predicting fetal death in 50 pregnant women with systemic lupus erythematosus (SLE) and/or lupus anticoagulant. Overall concordance of any abnormal determination of aCL during pregnancy with any abnormal determination of APTT was 76% (0.05 less than p less than 0.10). Fetal death occurred in 6/12 (50%) of patients with high APTT compared to 5/20 (16%) of patients with low APTT; fetal death occurred in 10/13 (77%) of patients with abnormal aCL and in 2/37 (5%) of patients with normal aCL. Sensitivity for predicting fetal death was .55 for APTT and .85 for aCL; specificity was .81 for APTT and .92 for aCL. Abnormalities of APTT and aCL are sufficiently frequently discordant to prevent equation of the 2 assays. ACL is the better assay for predicting fetal death.
...
PMID:Antibody to cardiolipin, lupus anticoagulant, and fetal death. 311 Apr 18

The INR system was developed to standardize PT reporting in patients on oral anticoagulants. We prospectively collected blood samples from 29 patients with liver impairment (INR 1.5-3.5). Control patients were on warfarin (n = 31). PT's were measured on an ACL-300 with three thromboplastin reagents. INR's were calculated using instrument specific ISI's. Other tests performed were FDP's, fibrinogen, aPTT, factors II, V, VII and X. The INR's for each patient in the study population using the three thromboplastin reagents were significantly different (p = 0.0001). Those for the control population were not (p = 0.0658). Fibrinogen, factors V, II and X were different at the 5% level of significance between the populations. FDP's were detected in 17 study subjects. The INR system is not valid for comparison of patients with liver impairment because different reagents do not give the same INR for the same sample. It is, however, no less valid than the use of PT with different thromboplastin reagents. Further study is recommended.
...
PMID:Assessment of the validity of the INR system for patients with liver impairment. 774 Apr 88

Five commercial rabbit brain thromboplastins were compared with an International Reference Preparation on an ACL coagulometer, using 90 patients stabilized on warfarin and 22 normal individuals. The prothrombin times were converted to INRs using the thromboplastin manufacturers' quoted ISI. The quoted ISIs were reassigned using orthogonal regression analysis and then used to recalculate INRs for patient and commercial INR control plasmas. This showed that the manufacturers' quoted ISIs and the INR control plasma results were inconsistent. With one thromboplastin the manufacturers quoted ISI changed from 1.17 to 1.05 whilst the control plasma results changed from an INR of 4.3 to an INR of 3.7 (manufacturer's INR, 3.3). In most routine laboratories ISI reassignment is not practical. We conclude that the availability of a reliable plasma calibrant is essential for the accurate calculation of INRs at a local level.
...
PMID:A comparison of five commercial thromboplastins: ISI re-evaluation on an automated coagulometer. 762 27


1 2 3 Next >>

---