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PubMed1992

[Presence of inhibitors of activated partial thromboplastin time (TTPA). Clinical repercussion in obstetric patients].

Partial thromboplastin time, activated with kaolin (TTPA) is a qualitative test used to find defects of some factor of intrinsic via of coagulation or to rule out the presence of some circulating inhibitor. The lupus anticoagulant (LA) is part of a group of several auto-antibody with pathogenic potential in several branches of medicine, mainly rheumatology, hematology and gyneco-obstetrics. In this last area the LA has been associated with different obstetrical repercussions. The purpose of this study was to determine the main obstetrical events associated with patients with circulating anticoagulants identified by TTPA with kaolin. Ninety six patients were included in cases-control study. Group I (n = 48) cases and Group II (n = 48) controls, were selected from the same population and information source. The cases were included when presenting prolongation of more than 4 seconds of TTPA activated with kaolin regarding a control with lack of correction with normal plasma. A registration sheet for data captation, was designed specially for this study. The comparability of both groups was established, as there were no differences (significant) among the variable considered as basal. The group of cases presented with a greater frequency of habitual abortion, neonatal death and thrombotic phenomena. This relationship of autoimmunological pictures with recurrent fetal loss and thromboembolic incidents has been consistently described in literature. To this respect, several immunological abnormalities. Including positive anticardiolipin antibodies and VDRL falsely positive. The incidence, in this country of these entities, is unknown. These observations show the need of a methodologic superation.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Habitual↗
PubMed2005

Causes of isolated prolonged activated partial thromboplastin time in an acute care general hospital.

INTRODUCTION: To determine the causes of isolated prolonged activated partial thromboplastin time (APTT) in an acute care general hospital setting so as to rationalise fresh frozen plasma usage. METHODS: A prospective study of consecutive patients with isolated prolonged APTT presenting to our hospital between February 2002 and January 2004 was performed. All patients had normal prothrombin time and thrombin time. For all patients, an initial 50:50 correction with plasma was done and a standard panel of tests was performed. These included detection of lupus anticoagulant using two different sensitive tests; measurement of coagulant factors VIII (FVIII), IX, XI and XII, which are involved in the intrinsic arm of haemostasis; von Willebrand factor antigen (vWF:Ag) levels and for those with FVIII levels less than 10 percent, an inhibitor assay using the Nijmegen modification of the Bethesda method. RESULTS: 177 patients were included in the study. The cohort was typical of an acute care general hospital patient population in Singapore in terms of age, sex and racial distribution. The most common cause of an isolated prolonged APTT in our study was the presence of lupus anticoagulant (53.1 percent of cases). In 31.6 percent of cases, obvious cause could be detected after our panel of tests. These patients mostly had mildly prolonged APTT that could be both correctable and non-correctable by normal plasma. Prolonged APTT due to factor deficiency was relatively rare with those that may potentially cause haemorrhagic problems only accounting for 4.5 percent of cases. CONCLUSION: Our study suggests that most of the causes of isolated prolonged APTT do not lead to haemorrhagic complications. In fact, in a majority, it may signify an underlying thrombophilic condition. As a result, prolongation of APTT should be fully investigated and correction with fresh frozen plasma should be used only when appropriate.

Acute Disease↗
PubMed1992

Recombinant tissue factor as substitute for conventional thromboplastin in the prothrombin time test.

Relipidated recombinant tissue factor (r-TF) has been assessed in comparison with conventional rabbit brain thromboplastin (Manchester Reagent) for its suitability for measurement of prothrombin time (PT). The International Sensitivity Index (ISI) of r-TF calibrated against the International Reference Preparation BCT/253 (human plain) was found to be 0.96 and 1.12 with instrumental and manual techniques. Our study of plasmas from patients with congenital deficiencies of clotting factors covering a wide range of severity demonstrates that r-TF is able to detect even minor deficiencies of factors involved in the extrinsic and common coagulation pathways. Patients with liver diseases were correctly diagnosed with a prevalence of abnormal results comparable for both reagents. Between-assay reproducibility expressed as coefficient of variation was 2.3% and 3.9% at normal and abnormal PT levels. In conclusion, our evaluation shows that relipidated r-TF possesses the necessary requisites of sensitivity, diagnostic accuracy and reproducibility which make it a suitable candidate for PT determination both for monitoring oral anticoagulant therapy and diagnosing congenital and acquired clotting factor deficiencies. Moreover, being a highly defined reagent it may constitute a step forward in the standardization of PT testing.

Anticoagulants↗
PubMed1992

The precision of duplicate prothrombin time and partial thromboplastin time assays in neonates.

An evaluation of duplicate prothrombin time (PT) and activated partial thromboplastin time (PTT) assays was performed in 277 neonatal samples. Performance criteria were analyzed to determine whether single vs duplicate procedures could be utilized reliably without exposing the neonates to the risk of erroneous PT and PTT results. In addition, we evaluated whether this approach might decrease phlebotomy and hence reduce the number of blood transfusions administered. For PT assays, 97.5% (270/277) of the duplicate results were different by 1 second or less. Only 2.5% (7/277) differed by 3 seconds. For PTT duplicates, 75.0% (207/277) of the values were different by 2 seconds or less and 13.0% (36/277) by 2 to 4 seconds. An additional 12.3% (34/277) were discrepant by as many as 4 seconds. The largest discrepancies occurred in specimens with markedly elevated PT and PTT results, indicative of a significant coagulopathy. In addition, heparin neutralization was performed successfully in 22 neonatal blood specimens showing either partial or full correction of PTT values due to heparin specimen contamination. This study indicates that single PT and PTT assays as well as heparin neutralization tests can be accurately performed and may be able to reduce blood donor exposure by as many as one blood transfusion every 2 to 3 days of hospitalization.

Heparin Antagonists↗
PubMedDate not supplied

Isolated prolongation of activated partial thromboplastin time following wasp sting.

Reactions after bee or wasp sting are similar to anaphylaxis. Symptoms such as weakness, fatigue, vomiting, diarrhea, urticaria, and hypotension may occur. Serious toxic reactions usually occur after numerous stings. Massive bee envenomations can result in immediate onset of shock, hemolysis, rhabdomyolysis, disseminated intravascular coagulation (DIC), coma, and renal failure. In milder cases, patients may only have isolated prolonged activated partial thromboplastin time (aPTT) and normal prothrombin time (PT), clinically without a tendency to bleed. As a rule, they recover spontaneously without any complication. We report three cases of wasp stings; they all manifested prolongation of aPTT and finally recovered completely. Isolated prolongation of aPTT in cases of wasp stings may be related to an extract from the venom inhibiting the coagulation pathway.

Animals↗
PubMed2005

[Deviation of activated partial thromboplastin time from optimal level after 12 hours of intravenous infusion of unfractionated heparin -- an independent predictor of recurrence and unfavorable 30-day prognosis in patients with myocardial infarction].

Aim of the study was to assess significance of deviations of activated partial thromboplastin time (APTT) from optimal level (50-75 sec) after 48 hours of intravenous infusion of unfractionated heparin (UFH) in streptokinase treated patients with myocardial infarction (MI) for prognosis of nonfatal reinfarction and cumulative criterion comprising cardiac death, nonfatal MI and early postinfarction angina. Infusion of streptokinase (1,500,000 U in 30-60 min) was carried out after loading dose of aspirin (250 mg) and intravenous bolus (5,000 U) of UFH in 75 patients (age 34-76 years) admitted within 6 hours after onset of acute ST-elevation MI. UFH infusion was started prior to termination of administration of streptokinase and continued for 48 hours. During first 12 hours infusion rate was 1,000 or 800 U/hour in patients with body mass > or = 80 and < 80 kg, respectively. During initial 12 hours infusion rate was corrected if at 6 hours APTT was less than 40 or exceeded 150 sec. After 12 hours a nomogram was used for UFH dose adjustment according to APTT. Maximal number of optimal APTT values during UFH infusion just reached 50%. During first 12 hours prevailed values above 75 sec, after 24 and 36 hours -- values below 50 sec. Deviation of APTT from optimal level in 12 hours after onset of UFH infusion was the only independent predictor of nonfatal recurrent MI during following 30 days (relative risk [RR] 9.01, 95% confidence interval [CI]1.1 to 77.2; p=0.043). Independent predictors of cumulative criterion were level of risk of death according to TIMI scale (RR 1.47, 95% CI 1.-3 to 2.11; p=0.036) and deviation of APTT from optimal level in 12 hours after onset of UFH infusion (RR 3.24, 95%CI 1.05 to 10.5; p=0.046). It should be noted that rather than suboptimal excessive hypocoagulation by 12th hour of UFH infusion was associated with worse prognosis. APTT levels in 6, 24, and 36 hours of UFH infusion had no prognostic significance in relation to events assessed in the study.

Adult↗
PubMed1992

Evaluation of prothrombin time and partial thromboplastin time.

Prothrombin time (PT) and partial thromboplastin time (PTT) tests are commonly ordered for hospitalized patients. A significant reduction in laboratory workload and expense can be achieved if these tests are ordered appropriately. The likelihood that the patient will benefit from these tests is small.

American Medical Association↗
PubMed2006

[The impact of heparin bolus from dysfunctional lumen of dual lumen central venous catheter on activated partial thromboplastin time during hemodialysis: is additional heparinization necessary?].

AIM: The aim of the study was to determine the influence of the heparin bolus, which was administered to a patient due to incapability to aspire heparin from the dysfunctional lumen of dual lumen central venous catheter (CVK), on activated partial thromboplastin time (APTT) values during hemodialysis (HD), as well as to determine the need of additional administration of heparin during HD. PATIENTS AND METHODS: The first group of examinees consisted of 19 patients with chronic renal failure (CRF) on whom the dual lumen CVK was applied as temporary vascular access, whereby the aspiration of heparin from one of its lumens was impossible. Prior to HD, a coagulogram was determined for all the patients. The testing of this group was carried out in accordance with two different protocols: protocol A and protocol B. Under protocol A, 7,500 IU of unfractioned heparin was injected into the patients' circulation from the dysfunctional lumen of CVK. During the four-hour HD process, APTT were determined after ten minutes, after hours 1, 2 and 3, and at the end of HD. During HD, no heparin was administered and every hour during HD there was visual evidence of blood clots in portions of the extracorporeal circuit system. Under protocol B, the APTT values were determined in the same group of patients according to the previous protocol, with the exception of 750 IU of heparin per hour being administered by continuous infusion to the patients during hours 3 and 4. The second group of examinees consisted of patients with CRF who have undergone dialysis via an arteriovenous fistula, while the testing was carried out under protocol C. The examinees in this group received a bolus of 2,500 IU of heparin at the beginning of HD, followed by a continuous administration of 750 IU of heparin per hour during the first three hours of HD (a total of 4,750 IU during the entire HD). During hour 4, HD was carried out without the administration of heparin. The protocol of determining APTT was identical to that carried out on the previous group of patients. RESULTS: APTT values prior to HD: A=34.5 +/- 4.27 sec., B=32.38 +/- 4.16 sec. (p=0.457), C=33.66 +/- 3.63 sec. (p=0.245 in relation to protocol A and p=0.281 in relation to protocol B). APTT values ten minutes after the administration of the heparin bolus: A=210 +/- 21.42 sec., B=204.83 +/- 20.82 sec. (p=0.453), C=47.88 +/- 4.26 sec. (p=0.000 in relation to protocols A and B). APTT values after one hour: A=156 +/- 32.76 sec., B=159.66 +/- 30.39 sec. (p=0.377), C=43.88 +/- 4.5 sec. (p=0.000 in relation to protocols A and B). APTT values after two hours: A=81.54 +/- 0.41 sec., B=74.61 +/- 36.39 sec. (p=0.331), C=40.55 +/- 5.29 sec. (p=0.000 in relation to protocols A and B). APTT values after three hours: A=49.6 +/- 8.38 sec., B=59 +/- 8.93 sec. (p=0.395), C=37.88 +/- 2.58 sec. (p=0.000 in relation to protocols A and B). APTT values at the end of HD: A=40.5 +/- 3.97 sec., B=51.44 +/- 5.07 sec. (p=0.154), C=36.66 +/- 4.22 sec. (p=0.399 in relation to protocol A and p=0.222 in relation to protocol B). Clotting was noticed during the third hour of HD in 11 (57.89%) patients under protocol A, in two (10.5%) patients under protocol B and in three (15.78%) patients under protocol C. After comparing proportions for protocols A and C p=0.02, for protocols B and C p=0.998 and for protocols A and B p=0.006 CONCLUSION: Patients who received the heparin bolus from the dysfunctional lumen of dual lumen CVK needed an additional administration of heparin during hours 3 and 4 of HD in order to reduce the frequency of clotting in the extracorporeal circuit system. The frequency of clotting during HD in this study was not dependent on the total dosage of administered heparin, but rather on the means of its administration.

Anticoagulants↗
PubMed1991

[The determination of tissue thromboplastin activity in cells].

A method for estimation of thromboplastin activity in blood and tissue cells has been developed, experimentally and theoretically substantiated. Blood plasma free from blood coagulation contact phase factors is used as a substrate for the detection of thromboplastic activities of blood and tissue cells.

Humans↗
PubMed1991

[Prothrombin time, activated partial thromboplastin time, plasma fibrinogen determination. Comparison of two automated coagulation systems: Koagulab 40-A and ACL-100].

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).

Autoanalysis↗
PubMed1991

One-step chromogenic equivalent of activated partial thromboplastin time evaluated for clinical application.

We evaluated the clinical usefulness of a recently developed semi-automated one-step chromogenic equivalent of activated partial thromboplastin time (APTT; Behring). This simple test is easily adaptable for automation. Generally, the results with this chromogenic one-step APTT were at least as precise as those obtained with comparative coagulometric methods. The chromogenic one-step APTT showed, both in vitro and in vivo, adequate sensitivity to congenital intrinsic factor deficiency but no sensitivity to Factor VII deficiency. Unlike a two-step coagulometric APTT (Dade), the one-step chromogenic APTT seemed sensitive to activation products of the contact system, which are present in immunoadsorbed factor-deficient plasma. The in vitro sensitivity of the chromogenic APTT to heparin was comparable with that of a coagulometric APTT, but the sensitivity to heparin in patients' samples differed slightly. The chromogenic APTT is relatively insensitive to anomalies in the fibrinogen-fibrin conversion. Finally, we observed discrepancies between the chromogenic and coagulometric APTT results for plasma of patients with disseminated intravascular coagulation. We conclude that this one-step chromogenic APTT warrants further evaluation for possible use as a routine test for the clinical laboratory.

Amino Acid Sequence↗
PubMed1991

High level expression of recombinant human tissue factor in Chinese hamster ovary cells as a human thromboplastin.

Tissue factor (TF) is the high affinity transmembrane receptor and cofactor for cellular initiation of the plasma coagulation protease cascades by factor VIIa. We describe the synthesis of recombinant huTF by stably transfected CHO cell lines carrying integrated huTF DNA, and the isolation of huTF glycoprotein with specific functional activity equivalent to natural huTF. The expression vector (pCDM8), carrying the cytomegalovirus promoter to drive transcription of a partial cDNA construct encoding the complete huTF protein chain, was cotransfected with a plasmid containing the neomycin resistance gene for selection. These clones were further selected for level of expression of huTF protein. Optimal expression compatible with stability and cell growth was approximately 13.5 x 10(6) molecules per cell. To our knowledge, this is one of the highest levels of expression described for a recombinant transmembrane receptor in mammalian cells. Recombinant huTF protein was obtained by single-step immuno-affinity purification, and exhibits heterogeneity due to N-linked glycosylation. The protein was indistinguishable from natural huTF based on functional properties of the glycoprotein reconstituted in lipid vesicles, and expression of conformational epitopes. Large scale production of recombinant huTF is feasible to permit basic studies of protein structure as well as for design of huTF thromboplastin reagents.

Animals↗
PubMed1991

Effect of lupus anticoagulants on the activated partial thromboplastin time. Results of the College of American Pathologists survey program.

Lupus anticoagulants are antibodies that interfere with in vitro phospholipid-dependent coagulation reactions. In vivo, they have been associated with a variety of thromboembolic problems. Samples from patients with lupus anticoagulants were included in the 1986 and 1987 College of American Pathologists proficiency survey program. Participant performance on these samples demonstrated significant variation in the responsiveness of different activated partial thromboplastin reagents to lupus anticoagulants. The level of factor VIII in these samples reported by the participants also varied with the reagent used. Follow-up studies demonstrated striking reagent-dependent differences in the dilutional effect on apparent factor VIII, IX, XI, and XII activity. These results point out the importance of selecting sensitive and responsive reagents for appropriate identification of lupus inhibitors. In addition, the results indicate that the choice of reagent used for factor assays can affect the apparent factor activity as well as whether a dilutional effect is noted when a lupus anticoagulant is present in the test sample, an important consideration when trying to distinguish a lupus anticoagulant from a specific factor inhibitor.

Autoantibodies↗
PubMed1991

Early response in septicemia in newborns and their mothers. Effect of Escherichia coli, Streptococcus agalactiae and tumor necrosis factor on lactoferrin release and the generation of tissue thromboplastin.

Using a whole blood in vitro model, we have investigated the effect of Escherichia coli (E. coli), Streptococcus agalactiae (group B streptococci, GBS) and tumor necrosis factor alpha (TNF) on the generation of lactoferrin (LF), interleukin-1 beta (IL-1) and tissue thromboplastin (TPL) in healthy newborns at term and their mothers. E. coli (at a final concentration of 10(7)/ml) significantly increased the release of LF in whole blood from newborns after 20 as well as 60 min stimulation, and in samples from their mothers after 60 min stimulation. A significant increase in the release of LF was observed in both newborns and their mothers after 20 and 60 min stimulation with TNF (at a final concentration of 1000 pg/ml). A combination of TNF/E. coli or TNF/GBS never gave any significant additional stimulatory effect. After stimulation with E. coli or GBS (both at a final concentration of 10(7)/ml) for 60 min a significant increase in production of TNF and TPL was observed in newborns. In newborns a significant increase in production of TNF and TPL was observed also after 20 min stimulation with E. coli. TNF (at a final concentration of 1000 pg/ml) significantly increased the generation of TPL after 20 and 60 min stimulation in both groups. There was a tendency for a greater release of LF and generation of TNF and TPL in samples from newborns compared with their mothers, but the differences were not statistically significant. E. coli, GBS and TNF had no significant effect on the production of IL-1.

Escherichia coli↗
PubMedDate not supplied

Sensitivity of the Azure heparin assay and comparisons with activated clotting time and whole blood partial thromboplastin time.

In order to compare the Azure A Assay to other commonly accepted measures of heparinization, samples of fresh donor sheep blood were prepared with known levels of heparin between 0 and 9 U/ml. For each sample, two determinations of the Activated Clotting Time (ACT) and Whole Blood Partial Thromboplastin Time (WBPTT) were performed. Similarly, an Azure A Assay standard curve of absorbance versus heparin concentration was constructed for the same blood. Three replicates of the procedure were performed, and the average relative error in each assay was computed as the 95% confidence interval on the regression line divided by the slope of the regression curve. Parallel studies were also performed to assess the effect of various plasma constituents on the Azure Assay. Results indicate that all of the assays are equally accurate for heparin levels at or below 2 U/ml, while the ACT and Azure assays are equivalent at heparin levels near 4 U/ml, but the WBPTT is not usable at concentrations above 2 U/ml. The Azure Assay is not sensitive enough for very low heparin levels (less than 1 U/ml), but it is quite accurate and, indeed, is the only rapid assay for heparin concentrations higher than 4 U/ml. In the sensitivity studies, variations in albumin levels and plasma platelet count were shown to have a significant effect on the accuracy of the Azure assay, whereas calcium levels had no effect.

Animals↗
PubMed1990

[Interaction of lectins with tissue thromboplastin].

Exo- and endolectins affined to N-acetylgalactosamine, N-acetylglucosamine, galactose, mannose and fucose, added in vitro to suspension of tissue thromboplastin from human brain, suppress its blood coagulation activity by 50-88% (p less than 0.05). This result has been considered as an argument for the advantage of the opinion that the specific blood coagulation centre of apoprotein III is located at the extracellular side of the cytoplasmic membrane.

Humans↗
PubMed1990

Nuclear textural changes preceding endotoxin mediated enhancement of thromboplastin synthesis in human endothelial cells in vitro.

Human vascular endothelium plays a major role in hemostatic processes. Human venous endothelial cells (HEC) may promote coagulation by generation of thromboplastin. This tissue factor production is enhanced by bacterial lipopolysaccharide (LPS). However, the mechanisms of this enhancement remain unclear. In order to quantify by image analysis the nuclear modifications induced by LPS on HEC, umbilical cord vein HEC were cultured in vitro with or without E. coli LPS (10 micrograms/ml) for 0 to 6 h. At the end of culture, tissue factor expression was evaluated by the ability of a cellular extract to shorten the coagulation time of human citrated plasma. Simultaneously, the morphology of LPS treated and control HEC was analysed using a SAMBA 200 cell image processor after Feulgen staining. This analysis indicates that LPS treatment induces nuclear modifications as early as 1 h after culture onset, before any tissue factor expression. This activity appears only between 2 and 4 h of culture with LPS. Our data show that image analysis permits the detection of very early nuclear events in HEC and that these events precede the expression of functional properties which may be implicated in thrombotic processes.

Cell Nucleus↗
PubMed1989

Allogenic induction of thromboplastin synthesis in monocytes and endothelial cells. Biphasic effect of cyclosporin A.

Monocytes and endothelial cells were stimulated in co-culture with allogeneic lymphocytes to produce thromboplastin (TPL). The induction was biphasic, an early response (8-24 h) was greatly augmented by cyclosporin A (CS) (0.5-5 micrograms/ml) whereas the late response (day 3-4) was inhibited. Prednisolone inhibited both responses. Both drugs inhibited lymphocyte proliferation. Interferon-gamma decreased MLC TPL activity but increased thymidine incorporation. CD4+ cells were instrumental in inducing the early TPL peak in monocytes, whereas CD8+ cells decreased the TPL effect. With endothelial cells both T cell classes were equally effective. Conditioned medium from MLC as well as from co-cultures of endothelial cells and lymphocytes induced early TPL synthesis in endothelial cells. Upon allogeneic stimulation monocytes, but not endothelial cells, produced a significant amount of F-VII, most of which was apparently undercarboxylated.

Cyclosporins↗