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PubMed1990

[The use of a concentrate of antithrombin III and disaggregants in the preoperative preparation of patients with pulmonary tuberculosis].

A study of the blood coagulation system in 32 patients with pulmonary tuberculosis before surgical intervention showed that reduction of the antithrombine III activity and related enhancement of the thrombin formation reaction and suppression of deaggregation capacities of thrombocytes reflect the latent process of pathological intravascular blood coagulation. The authors suggest justification of restoring the reduced antithrombine blood capacitance and normalization of the deaggregation capacity of thrombocytes by means of the antithrombine III concentrate and disaggregants in the complex preoperative care.

Adolescent↗

PubMed1988

Determination of human thrombin-antithrombin III complex by enzyme immunoassay.

We have developed a specific and sensitive ELISA for the measurement of the TAT in human plasma. The assay follows the sandwich principle and uses two different antibodies directed against human thrombin and human antithrombin III, respectively. The anti-thrombin antibody population used for coating was purified by immunoadsorption on immobilized prothrombin and thrombin, respectively. Antithrombin III antibodies were conjugated with peroxidase. Plasma samples containing TAT were incubated in polystyrene tubes coated with anti-thrombin antibodies; after washing, peroxidase-conjugated antithrombin III antibodies were added and bound enzyme activity was subsequently measured using o-phenylenediamine. The assay was calibrated with definite concentrations (2.0 to 60 micrograms/l) of preformed purified TAT added to TAT-poor plasma. Plots of absorbance at 492 nm against TAT concentrations revealed a linear correlation (r = 0.98). A reference range from 0.85 to 3.0 micrograms/l was calculated from TAT concentration in plasma samples from 88 healthy donors (mean value +/- SD: 1.45 +/- 0.4 micrograms/l). In patients with deep vein thrombosis confirmed by phlebography (n = 15), TAT was found up to 7-13 micrograms/l. Patients with septicemia associated with a consumption coagulopathy (n = 10) showed markedly increased TAT values (greater than or equal to 10 micrograms/l). From these data it can be concluded that measurement of TAT might be a parameter for detection of a latent clotting pathway activation.

Antithrombin III↗

PubMed1989

[Levels of antithrombin III and proteins C in the newborn infant].

Antithrombin III and protein C levels were studied in cord blood from 91 babies born at term with weight adequate to their gestation age. No history of drug ingestion or any other cause of impaired blood coagulation in newborns was present in any of the mothers, and none of these had had thromboembolic diseases. Basic coagulation study and clinical status were normal in all the newborns. Antithrombin III was measured as antigen concentration and functional heparin cofactor, both values being similar (ratio: 0.97) and significantly lower than those of adults (p less than 0.001). Antigenic protein C was assayed by enzyme immunoassay, the value attained being also significantly lower than that of normal adults (p less than 0.001). Factor VII: C rates were assayed in order to establish the protein C/factor VII: C relationship, since this might be useful in detecting protein C deficiency due to the similar biological characteristics of both proteins. It was concluded that health normal newborns show decreased antithrombin III and protein C rates, probably due to lack of liver maturity.

Antithrombin III↗

PubMed1985

Sensitivity of thrombin and plasmin to heparin and antithrombin III.

Thrombin and plasmin are inactivated by antithrombin III at different rates. Heparin, at a catalytic amount, increases primarily the inactivation rate of thrombin. The two proteinases compete for heparin, i.e. heparin is preferably attached by thrombin. Furthermore, fibrinogen as well as fibrin protect plasmin against inactivation by antithrombin III. However, at high concentration of heparin, plasmin inactivation by antithrombin III is accelerated even in the presence of fibrinogen or fibrin.

Antithrombins↗

PubMed1987

Structure and affinity for antithrombin of heparan sulfate chains derived from basement membrane proteoglycans.

Metabolically 35S- or 3H-labeled heparan sulfate was isolated from murine Reichert's membrane, an extraembryonic basement membrane produced by parietal endoderm cells, and from the basement membrane-producing Engelbreth-Holm-Swarm mouse tumor. The polysaccharides were subjected to structural analysis involving identification of products formed on deamination of the polysaccharides with nitrous acid. The polysaccharide from Reichert's membrane contained N- and O-sulfate groups in approximately equal proportions. It bound almost quantitatively and with high affinity to antithrombin. A high proportion of antithrombin-binding sequence was also indicated by the finding that 3-O-sulfated glucosamine residues accounted for about 10% of the total O-sulfate groups. In contrast, at least 80% of the sulfate residues in the heparan sulfate isolated from the mouse tumor were N-substituents. Only a minor proportion of this polysaccharide bound with high affinity to antithrombin, and no 3-O-sulfated glucosamine residues were detected. These results are discussed in relation to the possible functional role of heparan sulfate in basement membranes.

Animals↗

PubMed1986

Abnormal properties and behaviors of antithrombin III found in a thrombophilic patient: defective biological functions and dissimilar antigenic determinants.

Abnormal properties of antithrombin III have been found in a 55-year-old male who has been thrombophilic over the last seven years. They are characterized by defective inhibition of thrombin and activated blood coagulation factor X, reduced affinity to heparin and partial immunological identity with the normal molecule. The antithrombin III molecule, however, preserves a single-chain structure and an apparently identical molecular weight with that of the normal molecule. It is, thus, very unlikely that the impaired functions of antithrombin III in the patient's plasma are induced by possible proteolytic modifications of the molecule by thrombin or other related activated blood coagulation factors. Since no other members of his immediate family have been found to be affected, the abnormality may be acquired rather than genetically determined, although further investigation is necessary for the elucidation of the abnormality of the molecule.

Antithrombin III↗

PubMed1987

Long-term adjuvant therapy with tamoxifen: effects on sex hormone binding globulin and antithrombin III.

Plasma levels of luteinizing hormone, sex hormone binding globulin, and antithrombin III were measured in pre- and postmenopausal breast cancer patients receiving adjuvant combination chemotherapy or combination chemotherapy and long-term tamoxifen therapy. The aim was to determine the estrogen-like effects of tamoxifen. The premenopausal patients had received tamoxifen for between 434 and 2592 days and postmenopausal patients between 91 and 1560 days. Tamoxifen caused a consistent rise in sex hormone binding globulin in premenopausal (P less than 0.03) and postmenopausal (P less than 0.01) patients compared to chemotherapy controls. Luteinizing hormone levels were only significantly lowered (P less than 0.008) in premenopausal patients compared to chemotherapy controls. Antithrombin III levels were significantly depressed (P less than 0.001) in postmenopausal patients compared with chemotherapy controls. However, none of the patients had a value that was depressed by more than 30% of the laboratory control (the level of clinical significance). The mean for the group was 90% +/- 4 (mean +/- SD, N = 11). The estrogen-like rise in sex hormone binding globulin produced by adjuvant tamoxifen therapy could be advantageous for maintaining the antiestrogenic action of the drug. A decrease in antithrombin III occurred but was not within a range of clinical concern. We recommend, however, that patients with a history of thromboembolic disorders should be monitored carefully if placed on tamoxifen therapy.

Adult↗

PubMed1987

[Antithrombin III inhibition of the reaction to thrombin excitation of the anticoagulation system].

It has been established that intravenous administration of alpha-thrombin-antithrombin III preparations (1 mkM) has practically no effect on anticoagulation parameters (thrombin time, additive fibrinolytic activity, nonenzymatic fibrinolysis and nonenzymatic fibrinolytic activity). Administration of 1 mkM of alpha-thrombin caused a statistically significant increase of all the parameters. The experiments on perfusion of the humorally isolated sinocarotid area of the rabbit with alpha-thrombin-antithrombin III preparations (1.25 mkM) showed no changes peculiar to the induction of anticoagulation response with thrombin. It is concluded that antithrombin III blocks the ability of thrombin to activate anticoagulation system function.

Animals↗

PubMed1985

Changes in antithrombin, antiplasmin, and plasminogen during and after cardiopulmonary bypass.

Platelet counts and several clotting parameters, especially antithrombin, alpha 2-antiplasmin, and plasminogen, were determined in 33 patients undergoing cardiopulmonary bypass surgery. Except for Factors VIII and XI, all activities measured fell significantly as the patients were placed on the pump. This initial drop paralleled the drop in hematocrit, i.e., the drop was most likely due to hemodilution. During the entire procedure the activities remained decreased, again paralleling the hematocrit. Only the drop in platelet counts was greater than the hematocrit, suggesting additional consumption during bypass. In the ICU a second significant drop in antithrombin, prothrombin, and Factor V was noted that was not reflected by a drop in hematocrit. The cause for this is not known at this time. Although the patients with the lowest antithrombin levels, compared to the highest levels in the ICU seemed to have a greater need for protamine and blood and had greater chest tube drainage, none of these changes were significantly different. Comparisons between activated clotting times (ACTs) and actual heparin levels revealed a good correlation (0.886). Good correlations were also noted when manual factor assays were compared with automated assays using an automated analyzer suggesting the potential use of automation and profiling for these patients. Possible reasons for some of the most commonly encountered postoperative bleeding problems are discussed.

Adult↗

PubMed1985

A role for pericellular proteoglycan in the binding of thrombin or antithrombin III by the blood vessel endothelium? The effects of proteoglycan-degrading enzymes and glycosaminoglycan-binding proteins on 125I-thrombin binding by the rabbit thoracic aorta in vitro.

Rabbit thoracic aorta segments were treated with either proteoglycan-degrading enzymes or with glycosaminoglycan-binding proteins to examine the nature of the endothelial and subendothelial binding sites of 125I-thrombin. Treatment (5-30 min) with enzymes (heparitinase, chondroitinases AC or ABC) caused a decrease in 125I-thrombin binding by the endothelium (30-70%) and by the subendothelial (intima-media) layer (20-50%); a low-specificity protease destroyed endothelial binding almost entirely and reduced binding to the subendothelium by approximately 60% over a similar period. Of the glycosaminoglycan-binding proteins, pretreatment of the aorta wall with protamine caused a 30% decrease in thrombin binding to the endothelium whereas lipoprotein lipase (present during 125I-thrombin uptake) decreased binding by up to 40%. Pretreatment with antithrombin III did not significantly affect binding of either 125I-thrombin or 125I-FPR-inactivated thrombin. In contrast to thrombin, 125I-antithrombin III was not readily uptaken by the aorta segments. These observations indicate that, whereas the minimal binding by 125I-antithrombin III probably does not involve endothelial proteoglycan, a strong case can be made for endothelial and subendothelial proteoglycan binding sites for thrombin.

Affinity Labels↗

PubMed1985

High and low anticoagulant activity heparins. Preparation in large scale and degree of complexation with antithrombin III.

Heparin was separated into fractions with high and low anticoagulant activities by selective barium precipitation, gel filtration and ion exchange chromatography methods. Enrichment in the anticoagulant activities were observed in fractions with high molecular weight or high degree of sulfation. The combination of selective barium precipitation and ion exchange chromatography led to the preparation of heparins with very high anticoagulant activities (300 IU/mg). These heparins have a high affinity for antithrombin III (greater than 80%) and were undistinguishable from those prepared by antithrombin III affinity chromatography regarding molecular weight, sulfate/hexosamine ratio, degree of binding to antithrombin III, electrofocusing pattern and anticoagulant activity. These methods allow now the preparation in industrial scale of heparins with high anticoagulant activities for in vivo studies.

Animals↗

PubMed1979

Fractionation of low molecular weight heparin species and their interaction with antithrombin.

Preparations of low molecular weight porcine heparin with an average specific anticoagulant activity of 94 units/mg were fractionated into "active" and "relatively inactive" forms of the mucopolysaccharide of approximately 6000 daltons each. The active fraction was further subdivided into various species with descending but significant affinities for the protease inhibitor as well as decreasing but substantial anticoagulatn potencies. "Highly active" heparin (approximately 8% of the low molecular weight pool) possesses a specific anticoagulant activity of 350 +/- 10 units/mg. The relatively inactive fraction (67% of the low molecular weight pool) exhibits a specific anticoagulant activity of 4 +/- 1 units/mg. The binding of highly active heparin to antithrombin is accurately described by a single-site binding model with a KHep-ATDISS of approximately 1 X 10(-7) M. Variations in this binding parameter secondary to changes in environmental variables indicate that charge-charge interactions as well as an increase in entropy are critical to the formation of the highly active heparin-antithrombin complex. The interaction of relatively inactive heparin with the protease inhibitor is characterized by an apparent KHep-ATDISS of 1 X 10(-4) M. In large measure, this is due to small amounts of residual active mucopolysaccharide (0.5%). The ability of the highly active heparin to accelerate the thrombin-antithrombin interaction was also examined. We were able to demonstrate that the mucopolysaccharide acts as a catalyst in this process and is able to initiate multiple rounds of enzyme-inhibitor complex formation. The rate of enzyme neutralization is increased to a maximum of 2300-fold as the concentration of heparin is raised until the inhibitor is saturated with mucopolysaccharide. Further increases in heparin concentration result in a reduction in the speed of enzyme neutralization. This appears to be due to the formation of thrombin-heparin complexes. A mathematical model is given which provides a relationship between the initial velocity of enzyme neutralization and reactant concentrations.

Antithrombins↗

PubMed1979

Central retinal vein occlusion in a patient with familial antithrombin III deficiency: case report.

A 60-year old man with familial antithrombin III deficiency, a primary cause of hypercoagulation, developed central retinal vein occlusion. Familial antithrombin III deficiency is inherited as an autosomal dominant condition. It is characterized by recurrent episodes of thromboembolism. The occurrence of central retinal vein occlusion in a person with familial deficiency of antithrombin III suggests the possibility of a casual relationship.

Animals↗

PubMed1976

The effect of antithrombin III on the activity of the coagulation factors VII, IX and X.

Antithrombin III, purified to homogeneity according to polyacrylamide gel disc electrophoresis and immunoelectrophoresis, inhibited the activity of purified factor IXa and Xa, whereas factor VII was not inhibited either in the active or in the native form. Antithrombin III is the single most important inhibitor of factor Xa in plasma. Factor Xa does not, however, reduce the activity of antithrombin III against thrombin.

Antithrombins↗

PubMed1982

[A study of antithrombin systems during heparin therapy].

Plasma levels of three thrombin inhibitors (antithrombin III--AT-III-, alpha 2 macroglobulin - alpha 2M -; alpha 1 antitrypsin - alpha 1 AT-) were measured, together with total plasma antithrombin activity (Howie's method), in 19 hospital patients with venous thromboembolic disease before and during heparin therapy. A decrease in AT III levels was observed during treatment and found to correlate significantly with heparin plasma levels, but there were no significant changes in alpha 2M and alpha 1 AT levels. Variations in total plasma antithrombin activity were not significant. In 9 patients whose AT III levels were under 60% a significant increase in alpha 2M level was noted. The therapeutic problems associated with this category of patients are discussed.

Antithrombin III↗

PubMed1982

[Heparin and antiheparin in young children. 1. Report: development of a method for determining heparin and antiheparin in the antithrombin-thrombin system].

A new method of determining the biological activity of heparin and antiheparin is described. The principle is based on measuring the coagulation time in the antithrombin-thrombin system. By using a partially purified antithrombin III preparation and after coagulating the plasma samples with small amounts of thrombin the measuring system proves to be mostly independent on the inhibitory content of the test plasmas to be investigated. Heat defibrinated plasma cannot be used because it has essential properties with a close affinity to heparin. Additions of sodium and calcium ions will make the system more sensitive. Criteria of reaction kinetics are used for standardizing the antithrombin-thrombin system. The heparin level of up to 0.01 U/ml and the antiheparin titre of up to 0.005 U/ml can be covered by the procedure presented. Thus, it has a high sensitivity. The quality controls which were performed give evidence of the high precision of this method.

Antithrombin III↗

PubMed1983

Interaction of heparin with histidine-rich glycoprotein and with antithrombin III.

The interaction between heparin, histidine-rich glycoprotein and antithrombin III was studied in purified systems. Histidine-rich glycoprotein binds heparin and thereby interferes with its interaction with antithrombin III, resulting in neutralization of the anticoagulant activity. This interaction occurs with clinical grade heparin as well as with high affinity (for antithrombin III) heparin and with a high affinity heparin fragment with Mr 4,300. Low affinity heparin competes with high affinity heparin for the binding to histidine-rich glycoprotein which results in an apparent increase of the anticoagulant activity of high affinity heparin. The interaction between heparin and histidine-rich glycoprotein is counteracted by Ca2+-binding anticoagulants, indicating that it is dependent on the presence of divalent metal ions. Ethylenediaminetetraacetate is a much more potent inhibitor of the interaction between heparin and histidine-rich glycoprotein than citrate.

Antithrombin III↗

PubMed1981

GAGs-potentiated inhibition of thrombin, factor Xa and plasmin in plasma and in a purified system containing antithrombin III - correlation with total charge density.

The ability of heparin and related glycosaminoglycans (GAGs) to accelerate the inhibition of thrombin, factor Xa and plasmin in plasma and in a purified system containing antithrombin III (At III) was studied using chromogenic peptide substrate assays. There was good correlation between the charge density of the mucopolysaccharides and the activities investigated. While the difference between potentiation of the antithrombin activity by GAGs in plasma and in the purified system was slight, the inhibition of factor Xa in plasma was more pronounced than in the presence of purified At III, indicating the mechanisms for GAGs-potentiated inhibition of thrombin and factor Xa are not identical. For the antiplasmin activity, there was a good correlation between the chemical structure and biological activity only in the pure system, confirming that the antithrombin-GAG complex plays a very limited role in the inactivation of plasmin in plasma.

Antithrombins↗