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PubMed1983

Plasminogen activator and thromboplastin activity from sheep alveolar macrophages.

Alveolar lavage cells from normal sheep were found to be composed of over 95% macrophages. When the cells were cultured, fibrinolytic and thromboplastin-like activities could be detected within 2-4 hours of incubation. As the number of cultured cells was increased the two activities in the conditioned medium increased proportionately. The cells were separated into two distinct subpopulations by means of a sedimentation velocity cell fractionation technique. The macrophage subpopulations were examined for differences in size, morphology, esterase staining and ability to release plasminogen activator and procoagulant activity respectively. These activities were confined to the large cell subpopulation. The fibrinolytic activity was shown to be plasminogen-dependent and could be inhibited by DFP. On the basis of this the fibrinolytic activity has been designated as plasminogen activator. The procoagulant activity was shown to be thromboplastin in nature because it was Factor VII dependent, inactivated by phospholipase C and not inhibited by DFP. The procoagulant activity has been designated as macrophage thromboplastin. The two activities could be distinguished on the basis of DFP inhibition.

Animals↗
PubMed1985

Inhibitory effect of 3-deazaadenosine on the thromboplastin response of stimulated human monocytes.

Immune complexes (IC), 12-O-tetradecanoylphorbol-13-acetate (TPA), endotoxin (LPS) and phytohaemagglutinin (PHA) induce thromboplastin activity in human peripheral blood monocytes. In the presence of transmethylation inhibitors 3-deazaadenosine (DZA) and homocysteine a dose-dependent inhibition of the thromboplastin response reaching about 60 per cent was observed, when IC, LPS or PHA was used as the stimulant. TPA-induced thromboplastin synthesis was more resistant (maximum 20 per cent inhibition).

Dose-Response Relationship, Drug↗
PubMed1987

Experimental gram-negative septicemia: thromboplastin generation in mononuclear phagocytes from different anatomical sites.

Rats were subjected to gram-negative septicemia induced by cecal perforation or were sham-operated. Thromboplastin values increased in blood monocytes (40-fold), peritoneal macrophages (115-fold) pleural macrophages (5-fold), splenic macrophages (3-fold), and lung alveolar macrophages (1.4-fold) in septic animals as compared to controls. In septic animals disseminated intravascular coagulation was evidenced by a significant (p less than 0.05) fall in fibrinogen, factor VII, X and platelets. A simultaneous and significant (p less than 0.05) decrease in thromboplastin content of tissue-specimens from lung and spleen was observed in rats with septicemia, whereas increased thromboplastin values were demonstrated in tissue-samples from cecum - the infectious focus. This might reflect mobilization of mononuclear phagocytes in favour of the site of infection.

Animals↗
PubMed1987

The development of monospecific antibodies against human thromboplastin apoprotein (apoprotein III) and their application in the immunocytochemical detection of the antigen in blood cells.

Human thromboplastin apoprotein (apoprotein III) purified by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) was purified a further 2-4 fold by PAGE in the presence of digitonin. Subsequent line immunoelectrophoresis of the protein revealed several lines, only one of which contained inhibitory antibodies. New inhibitory antibodies which were raised by using this particular line to immunize rabbits produced only a single line in immunoelectrophoresis of apoprotein III, with precipitated inhibitory antibodies being present only in the line. When these antibodies were used in electroblot immunobinding studies of crude thromboplastin after SDS-PAGE staining was found mainly in a single band of MW about 50,000, but also to some extent in immunologically related higher MW material. Prior deglycosylation of the thromboplastin using trinitrobenzenesulfonic acid resulted in a shift of the bulk of the main band representing an apparent MW reduction of 16%, and a corresponding shift in the position of protein with the capacity to bind inhibitory antibodies. Besides being a good criterion of specificity of the antibodies this also suggests that non-carbohydrate parts of apoprotein III may be involved in the interaction with Factor VII. Immunoperoxidase staining of unstimulated or endotoxin stimulated blood cells using the antibodies revealed the presence of significant amounts of apoprotein III only in stimulated monocytes, apparently available on the surface of the cells since it was detectable also by preembedding staining of fixed cells in suspension. The result is strong evidence that apoprotein III is synthesized de novo in monocytes upon endotoxin stimulation.

Antibodies↗
PubMed2005

Efficacy of low molecular weight heparin in a canine model of thromboplastin-induced acute disseminated intravascular coagulation.

The aim of this study was to test the efficacy of different dosages of low molecular weight heparin (LMWH) in acute DIC which was induced in anaesthetised dogs by 4 h infusions of a canine lung thromboplastin extract. In all animals during the first 2 h, development of acute DIC was characterised by decreasing fibrinogen concentrations, platelet numbers, factor V- and antithrombin activities. Two hours after starting the thromboplastin infusion, intravenous LMWH treatment in different dosages started in groups 2 and 3 to achieve plasma levels between 0.27+/-0.01 and 0.36+/-0.02 anti-FXaUml(-1) or 0.62+/-0.08 and 0.90+/-0.07 antiFXaUml(-1) (mean+/-SD), respectively, during the time period of parallel administration of thromboplastin and LMWH (group 1=control; 4 dogs/group). In this time period, changes in factor V activity and fibrinogen concentration did not differ between group 2 and the control group. This was in contrast to group 3. The results of this study indicate that an efficacious interruption of the consumption reaction in cases of severe canine DIC requires high plasma heparin levels.

Animals↗
PubMed2005

Effect of magnesium contamination in evacuated blood collection tubes on the prothrombin time test and ISI calibration using recombinant human thromboplastin and different types of coagulometer.

UNLABELLED: The purpose of the present study was to assess the effect of two types of evacuated blood collection tube on the prothrombin time and international sensitivity index (ISI) of Recombiplastin, a recombinant human thromboplastin. Vacutainer tubes were compared with Venoject II tubes. Magnesium contamination was detected in the sodium citrate solutions contained in the Vacutainer tubes with concentrations ranging from 1.1 to 1.5 mmol/l. In contrast, magnesium ions could not be detected in the Venoject II tubes. The prothrombin ratio was decreased by contamination with magnesium ions and, hence, the ISI was increased. The magnitude of the effect of magnesium contamination on the ISI was influenced by the type of coagulometer and increased in the order: ACL Advance (3%), ACL-300 (4%), Electra-1000 (6%). The ISI bias is transmitted to the international normalized ratio (INR). In the case of the Electra-1000, the INR bias would be approximately 6% at INR 3.0 if the two types of blood collection tubes would be used without distinction. In a secondary study, the effect of magnesium contamination on the prothrombin time was assessed with the current World Health Organization international reference preparation for recombinant human thromboplastin (rTF/95). Magnesium chloride added to patients' blood (0.2 mmol/l) induced 2.3% reduction of the INR determined with rTF/95 and the manual technique. CONCLUSION: The magnitude of the influence of blood collection tubes contaminated with magnesium on ISI and INR determined with recombinant human thromboplastin depends on the coagulometer.

Anticoagulants↗
PubMed1986

[Successes and failures of the activated partial thromboplastin time in the preoperative evaluation].

In a prospective study assessing haemostatic functions, the activated partial thromboplastin time was prolonged in 134 out of 10,229 patients studied, without an increase in the prothrombin or thrombin times; this abnormality persisted in only 37 of them on a new blood sample. A retrospective analysis was made of 265 patients who had such an isolated prolongation of the activated partial thromboplastin time on two successive blood samples: the causal abnormality remained unexplained in 135 patients; a well defined coagulation disorder without abnormal bleeding tendency was present in 110 patients (1 severe factor XII deficiency, 58 partial factor XI or XII deficiencies and 51 lupus anticoagulants); a bleeding disorder was diagnosed in 20 patients (8 haemophilias, 8 Von Willebrand's diseases, 4 factor VIII inhibitors). The well-iron efficacy of the activated partial thromboplastin time for detecting coagulation abnormalities is counter-balanced by some disadvantages such as the delay for biologic conclusions. In the preoperative assessment of haemostatic functions, rather than taking a routine approach, it would seem better to determine for each patient the need and the extent of biological testing according to the type of planned surgery, the clinical status of the patient and possible bleeding symptoms.

Blood Coagulation Tests↗
PubMed1981

Phorbol esters induce synthesis of thromboplastin activity in human monocytes.

12-O-Tetradecanoylphorbol 13-acetate (TPA), phorbol 12,13-diacetate and phorbol 12,13-didecanoate were all potent inducers of thromboplastin activity in human monocytes in vitro, whereas 4 alpha-phorbol 12,13-didecanoate and 4 alpha-phorbol had no such effect. A concomitant increase in titrable apoprotein III antigen was found (apoprotein III is the protein component of thromboplastin). The increase was inhibited by cycloheximide and actinomycin D and partly by alpha-amanitin. The increase of thromboplastin activity was therefore most likely due to synthesis de novo of apoprotein III. The response was approximately halved in the absence of serum or Ca2+. Retinol had a weak inhibitory effect, and retinoic acid was inhibitory only at concentrations that also induced signs of cytotoxicity. TPA caused an initial rise in monocyte cyclic AMP concentration of about 90-120 min duration. No increase in 45Ca2+ influx was induced over 2 h. Good correlation exists between induction of apoprotein III synthesis in monocytes in vitro and mouse skin-tumour promotion in vivo by the various phorbol derivatives. Substances inactive in tumour promotion do not induce the synthesis of apoprotein III. General activating and cytotoxic effects of TPA were monitored by determining release of lysozyme, beta-glucuronidase and lactate dehydrogenase.

Apoproteins↗
PubMed1977

Variation among commercial activated partial thromboplastin time reagents in response to heparin.

The activated partial thromboplastin time (APTT) has been advocated for monitoring heparin effect. This study was designed to determine the in vitro sensitivity to heparin of commercially available APTT reagents. Heparin was added in increasing concentrations to pooled citrated plasma. Fibrometer APTT determinations were performed at each concentration using General Diagnostics, Ortho, Dade, Hyland, and BBL reagents. A tilt-tube kaolin-activated partial thromboplastin time was also tested using a Sigma partial thromboplastin prepared by the method of Bell and Alton. The General Diagnostics, Sigma, and Ortho reagents displayed linear heparin sensitivity; the General Diagnostics APTT was prolonged 1 1/2-2 1/2 times in a plasma heparin range that prolonged a modified in-vitro Lee-White clotting times 2-3 times. The other reagents were either insensitive, too sensitive, or nonlinear in heparin response. Thus, commercial reagents vary widely in their in-vitro sensitivity to heparin.

Blood Coagulation↗
PubMed1980

Monitoring of heparin treatment. Comparison of thrombin time, activated partial thromboplastin time, and plasma heparin concentration, and analysis of the behavior of antithrombin III.

Three laboratory methods for monitoring heparin treatment have been compared using 63 plasma samples: the thrombin time, the activated partial thromboplastin time, and the measurement of the heparin concentration using a chromogenic substrate. A good correlation was found between the methods. However, the intensity of anticoagulation was identical in only 27 of the 63 samples (43%) when the thrombin time and the activated partial thromboplastin time were compared. Fully discordant results were recorded for four samples (6%). The thrombin time was found to be more closely related to the plasma heparin concentration than was the activated partial thromboplastin time. Both antithrombin-III activity and immunologic levels were lower in the group with strong heparinization. It is suggested that the thrombin time is a good and safe method for monitoring heparin treatment.

Antithrombin III↗
PubMed1983

Pseudo-prolongation of the partial thromboplastin time.

A patient with a negative personal and family history for bleeding was being prepared for bronchoscopy when an extremely long activated partial thromboplastin time was detected. Analyses for the contact phase factors were normal. It was determined subsequently that the prolongation was artifactual. The prolongation was due to a peculiar set of circumstances requiring an intrinsically short partial thromboplastin time, a rapid-acting commercial accelerating agent, and a clot-sensing device having a built-in lag phase longer than the resulting partial thromboplastin time. The authors wish to bring to the attention of laboratory personnel this curiosity.

Aged↗
PubMed1984

Proficiency testing and standardization of prothrombin time: effect of thromboplastin, instrumentation, and plasma.

Prothrombin times accumulated from ten different proficiency testing surveys were analyzed in terms of a linear additive model described by Evatt et al (Clin Lab Haemat 1981; 3:331-342). Different types of lyophilized plasma samples were used, i.e., plasmas artificially depleted of coagulation factors by adsorption to aluminum hydroxide, and pooled plasmas of patients receiving coumarin drugs. For each plasma sample, both instruments and thromboplastins had a highly significant effect on the prothrombin time. For most instruments and thromboplastins, a good correlation was found between instrument effect or thromboplastin effect and the mean prothrombin time if various artificially depleted plasma samples from a single manufacturer were used. Artificially depleted plasmas from a second manufacturer gave different relationships between estimated effects and mean prothrombin time. Relationships based on lyophilized pooled patient plasmas were different from those of artificially depleted plasmas from either manufacturer. The potential use of the additive linear model for standardization of the prothrombin time in monitoring oral anticoagulant therapy is discussed. Additional studies are required to establish the suitability of this model to define a universal scale for prothrombin times of fresh plasma samples of anticoagulated patients. If suitable, the model can be linked to the International Normalized Ratio proposed by the World Health Organization.

Analysis of Variance↗
PubMed1989

Special report: a simple system for the derivation of International Normalized Ratios for the reporting of prothrombin time results with North American thromboplastin reagents.

The World Health Organization international scale of reporting prothrombin time results is based on the calibration of thromboplastins against an international reference preparation to derive an International Sensitivity Index (ISI). Once the ISI has been assigned to an individual thromboplastin reagent, the derivation of International Normalised Ratios (INRs) for reporting results depends on mathematic formulae requiring a special calculator or mathematic tables. This causes difficulties and errors. A simplified system for interpretation of INRs with the range of thromboplastins widely used in North America is therefore presented, which obviates the need for mathematic procedures for the derivation of INR equivalents. It should thus facilitate the application of the INR system and of safer therapeutic ranges.

Calibration↗
PubMed2002

Significant increase of activated partial thromboplastin time by heparinization of the radial artery catheter flush solution with a closed arterial catheter system.

OBJECTIVE: Evaluate whether the use of a heparinized flush for an arterial catheter with a closed-loop blood sampling system leads to erroneous coagulation studies. DESIGN: Prospective study. SETTING: Twenty-two-bed surgical adult intensive care unit in a university hospital. PATIENTS: Sixty patients, 30 in each phase of the study. INTERVENTIONS: Phase 1: coagulation studies on a blood sample from a venous puncture and an arterial blood sample from an arterial catheter with heparinized flush. Phase 2: the same protocol but the arterial catheter was flushed with saline. MEASUREMENTS: Activated partial thromboplastin time, fibrinogen, percentage of prothrombin time, and international normalized ratio of prothrombin time on the venous and arterial samples. MAIN RESULTS: Activated partial thromboplastin time in the arterial blood samples taken from an arterial catheter with heparinized flush was significantly prolonged compared with the venous controls. This was not the case in blood samples from an arterial catheter with saline flush. The magnitude of this difference found by the Bland and Altman analysis was clinically significant. In 23.3% of the patients in phase 1, there was a difference of >50% between the arterial and venous sampled activated partial thromboplastin time, compared with 0% of the patients in phase 2 (p =.018). There was no difference between the venous and the arterial blood samples for the non-heparin-sensitive coagulation studies in both phases of the study. An explanation for these findings could be that there was release of heparin bound to the arterial catheter into the blood sample. CONCLUSION: A heparinized flush solution for the arterial catheter, when used together with a closed-loop blood sampling system, leads to erroneous results of heparin-sensitive coagulation studies. Heparin-sensitive coagulation studies, therefore, should not be analyzed on blood samples from such a system if a heparinized flush solution is used.

Anticoagulants↗
PubMed1988

Effects of phospholipase C, a tissue thromboplastin inhibitor, on pulmonary microembolism after missile injury of the limb.

Tissue thromboplastin probably plays an important role in the development of post-traumatic pulmonary microembolism. Infusion of purified human tissue thromboplastin in animals resulted in an intravascular coagulation and respiratory insufficiency. This could be inhibited by previous infusion of phospholipase C (PLC) from Bacillus cereus. We have studied the effects of PLC infusion on the course of post-traumatic pulmonary microembolism, induced by a high-energy (c. 700 J) missile trauma to the hind legs of pigs. The trauma resulted in a major muscular injury and an indirect femoral fracture. Untreated pigs developed intrapulmonary microemboli. The degree of microembolism in the lungs was measured quantitatively by external detection over the right lung of radiolabeled platelets and fibrin. Infusion of 80 micrograms PLC/kg/hour resulted in an accumulation of blood PLC associated with toxic reaction leading to increasing tachycardia and circulatory collapse after 10 hours. PLC infusion of 20 micrograms/kg/hour did not inhibit the pulmonary microembolism. A PLC-dose in between, viz. 40-50 micrograms/kg/hour, proved to efficiently inhibit most of the microembolism during the infusion period. Cessation of PLC infusion after 24 hours was accompanied by a later increase in pulmonary trapping of platelets and fibrin and decreases in paO2. Concomitantly there were opacities seen on chest X-rays. The results show that tissue thromboplastin is an important etiologic factor in post-traumatic pulmonary microembolism and that inhibition with phospholipase C can be of value in the prophylaxis of the syndrome.

Animals↗
PubMed2005

Preoperative screening for coagulopathy using prothrombin time and partial thromboplastin time in patients requiring primary cranial vault remodeling.

BACKGROUND: The aim of this study was to investigate the prevalence of abnormal preoperative screening prothrombin time and partial thromboplastin time in patients listed for primary cranial vault remodeling that required hematologic workup and their diagnoses and subsequent management. METHODS: This retrospective analysis was performed from January of 2000 to December of 2003 at the International Craniofacial Institute, Dallas, Texas, on a total of 168 patients. RESULTS: All patients had a normal prothrombin time. Abnormally raised partial thromboplastin time was found in six patients (prevalence of 3.57 percent), one who had factor XI deficiency, one who had a borderline factor XI deficiency and circulating inhibitor, one who had an intermittent factor XI deficiency and circulating inhibitor, one who had a borderline von Willebrand's disease with low factor XII, and the remaining two who had a circulating inhibitor of coagulation. Of these six patients, the perioperative management was altered in four of five patients, and one patient declined surgery out of fear of surgical morbidity. The surgery of one patient was aborted intraoperatively because of abnormal bleeding without clot formation after the calvarial burr holes had been drilled. The mean blood loss was 183 ml for the four patients with completed surgery and 100 ml for one patient. CONCLUSIONS: The authors conclude that even though the prevalence of abnormal screening partial thromboplastin time in these patients was low (3.57 percent), detection of an abnormal result required preoperative correction of coagulopathy in 80 percent of cases.

Blood Coagulation Disorders↗
PubMed1978

An inhibitor of fibrin formation in thromboplastins prepared by saline extraction of human brain.

Human brain is a common source of thromboplastin for the prothrombin time, where the end point is the conversion of fibrinogen to fibrin. Experiments showed that human brain also contains a proteolipid which inhibits the conversion of fibrinogen to fibrin. The proteolipid is removed when brain tissue is washed with acetone, but remains as a contaminant when brain is extracted with saline. For this reason prothrombin times on the same plasma are longer when saline extracts, rather than acetone dried preparations, are the source of thromboplastin. The proteolipid explains why the prothrombin time becomes shorter when saline extracts are diluted to standardize their activity against the British comparative thromboplastin.

Brain Chemistry↗
PubMed1978

An immunoradiometric assay for factor III (tissue thromboplastin).

A solid-phase immunoradiometric assay for tissue thromboplastin (factor III) has been established based on its displacing effect on the binding of 125I-labelled factor III-antibodies to polyvinyl tubes coated with the purified protein component of factor III (apoprotein III). By this method circulating tissue thromboplastin can be detected in experimental animals receiving infusions of crude or purified tissue thromboplastin and in patients undergoing major orthopaedic surgery.

Animals↗