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PubMed1986

Antithrombin, prekallikrein, and fibronectin levels in surgical patients.

Antithrombin (AT), prekallikrein (PK), and fibronectin (FN) levels were measured in the plasma of 290 patients. The mean (+/- SD) lowest AT level measured in 287 patients was 70% +/- 18% (normal, 75% to 120% of control). The mean lowest AT level in 81 septic patients (49% +/- 17%) was significantly lower than in the 206 patients without sepsis (78% +/- 22%). The mean AT level in 60 patients who died (42% +/- 22%) was significantly lower than in 227 patients who lived (78% +/- 19%). The mean lowest PK level measured in 71 patients was 42% +/- 17% (normal, 80% to 120%). The mean PK level in 32 septic patients (26% +/- 12%) was significantly lower than in 39 patients who were not septic (54% +/- 19%). The mean lowest FN level measured in 45 patients was 193 +/- 86 micrograms/mL (normal, 160 to 240 micrograms/mL). The mean FN level in 15 septic patients (128 +/- 72 micrograms/mL) was significantly lower than in the 30 nonseptic patients (266 +/- 84 micrograms/mL). Following AT, PK, and FN levels in critically ill surgical patients may allow earlier diagnosis and more effective treatment of sepsis.

Antithrombins↗
PubMed1996

Reduction of antithrombin III, protein C, and protein S levels and activated protein C resistance in polycythemia vera and essential thrombocythemia patients with thrombosis.

Patients with polycythemia vera (PV) or essential thrombocythemia (ET) show a high frequency of thrombosis. The reduction of hematocrit after phlebotomy and normalization of platelet counts do not completely eliminate thrombotic risk. Some preliminary studies reported a reduction in the concentration of natural anticoagulants (NA) in this group of patients. For this reason we evaluated protein S (PS) total antigen, antithrombin III (AT III), and protein C (PC) activity in 81 patients with chronic myeloproliferative disorders (33 with PV and 48 with ET). Data were compared with those obtained in 70 healthy sex- and age-matched subjects. Fifty-seven percent of patients (46 out of 81) showed one or more thrombotic episodes at diagnosis or during follow-up. Interestingly, we found a NA deficit in 43.5% of patients with thrombosis versus only 5.7% in the group of patients without thrombosis. These results may suggest new interpretations about the pathogenesis of thrombosis in PV or ET patients.

Adult↗
PubMed1999

Effects of low molecular weight heparin, alone or combined with antithrombin III, on mortality, fibrin deposits and hemostatic parameters in endotoxin-induced disseminated intravascular coagulation in rabbits.

The effect of low molecular weight heparin (LMWH) with or without antithrombin III (AT III) has been studied in a rabbit model of disseminated intravascular coagulation (DIC) induced by continuous infusion of 100 microg/kg/hr of Escherichia coli endotoxin for 6 hr. LMWH (5 and 10 IU/kg/hr/6 hr), alone or in combination with AT III (20 U/kg/hr/6 hr), or saline were administered simultaneously with endotoxin. Hemostatic markers at 0, 2, and 6 hr as well as kidney fibrin deposits and the mortality rate at 24 hr were determined. Rabbits receiving only endotoxin showed an impairment in hemostasis, as well as high kidney fibrin deposits and a high mortality rate. LMWH alone did not exert any effect. The simultaneous infusion of LMWH and AT III exerted a beneficial effect on the hemostatic markers and reduced the kidney fibrin deposits as well as the mortality rate in a LMWH dose-dependent manner. Fibrinogen and protein C consumption were significantly higher and renal fibrin deposits more intense in the rabbits that had died in the first 24 hr. There was also a significant positive correlation between kidney fibrin deposits and platelets, fibrinogen, and protein C consumption, taking the whole rabbit population. It is concluded that the simultaneous infusion of LMWH and AT III is useful in this DIC model and would make it possible to reduce significantly the AT III doses used when AT III is given alone.

Animals↗
PubMed1999

A novel and de novo spontaneous point mutation (Glu271STOP) of the antithrombin gene results in a type I deficiency and thrombophilia.

We describe a novel, de novo point mutation in one antithrombin (AT) allele resulting in type I AT deficiency and thrombophilia. Low plasma AT activity as well as low plasma AT antigen were documented in the propositus, but not in the parents, or in a male sibling. AT gene analysis by sequencing polymerase chain reaction-amplified genomic DNA from exon 5 of the propositus revealed a novel point mutation, GAG-->TAG at codon 271, resulting in a stop codon (Glu271STOP). This mutation was not demonstrable in the other members of his immediate family. DNA marker polymorphism analysis indicated the expected parentage. Based on allele frequency data for Caucasians in the United States the cumulative paternity index, or CPI, for the propositus and his father is 219,077. This corresponds to a probability of paternity of 99.9995% based on a prior probability of 50%. Included in this analysis is a linkage analysis of a trinucleotide repeat in intron 5 of the AT gene of the various family members, which also confirmed maternity and paternity. These studies provide documentation of the first spontaneous mutation of an AT gene in a thrombophilic individual, resulting in a type I AT deficiency.

Adolescent↗
PubMed1996

Modeling of serpin-protease complexes: antithrombin-thrombin, alpha 1-antitrypsin (358Met-->Arg)-thrombin, alpha 1-antitrypsin (358Met-->Arg)-trypsin, and antitrypsin-elastase.

Based on the most recent available crystal structures and biochemical studies of protease complexes of normal and mutant serine protease inhibitors (serpins), we have built models of the complexes: alpha 1-antitrypsin + human neutrophil elastase; alpha 1-antitrypsin Pittsburgh (358Met-->Arg) (Scott et al., J. Clin. Invest. 77:631-634, 1986) + tyrpsin; alpha 1-antitrypsin Pittsburgh (358Met-->Arg) + thrombin; and antithrombin + thrombin. All serpin sequences correspond to human molecules. The models show correct stereochemistry and no steric clashes between protease and inhibitor. The main structural differences in the serpins from the parent structures are: (1) the reactive center loop is inserted into the A-sheet as far as P12; (2) strand s1C is removed from the C-sheet; and (3) the C-terminus has changed conformation and interacts with the protease. In the absence of an X-ray structure determination of a serpin-protease complex, the demonstration that insertion of the reactive center loop into the A-sheet as far as P12 is stereochemically feasible provides structures of a protease-bound conformation of intact serpins with which to rationalize the properties of mutants, guide the design of experiments, and form a basis for further modeling studies, such as the investigation of the interaction of heparin with serpin-protease complexes.

Antithrombin III↗
PubMed1996

Effect of fibronectin on the binding of antithrombin III to immobilized heparin.

An objective of this research is to verify the mechanism of anticoagulant activity of surface-immobilized heparin in the presence of plasma proteins. The competition and binding interaction between immobilized heparin and antithrombin III (ATIII)/thrombin have been described in vitro. However, the strong ionic character of heparin leads to its specific and nonspecific binding with many other plasma proteins. Most notably, fibronectin contains six active binding sites for heparin which may interfere with the subsequent binding of heparin with ATIII or thrombin. Heparin was covalently immobilized through polyethylene oxide (PEO) hydrophilic spacer groups onto a model surface synthesized by random copolymerization of styrene and p-aminostyrene. The binding interaction of immobilized heparin with ATIII was then determined in the presence of different fibronectin concentrations. The binding interaction was studied by first binding immobilized heparin with ATIII, followed by the introduction of fibronectin; heparin binding with fibronectin, followed by incubation with ATIII, and simultaneous incubation of surface immobilized heparin with ATIII and fibronectin. The extent of ATIII binding to heparin in each experiment was assayed using a chromogenic substrate for ATIII, S-2238. The results of this study demonstrate that the displacement of ATIII from immobilized heparin was proportional to the fibronectin concentration, and was reversible. Furthermore, the binding sequence did not play a role in the final concentration of ATIII bound to immobilized heparin.

Anticoagulants↗
PubMed1982

Antithrombin III and anti-activated factor X activity in patients with acute promyelocytic leukemia and disseminated intravascular coagulation treated with heparin.

Two patients diagnosed as having acute promyelocytic leukemia (APL) and disseminated intravascular coagulation (DIC) were closely followed from the day of admission until completion of the first course of chemotherapy with serial coagulation studies including plasma levels of functional antithrombin III activity (AT III) by fluorometric analysis and anti-activated Factor X activity (anti-Xa) by coagulation assay. Both patients were treated with intravenous heparin and the presence of heparin in plasma was followed by the thrombin time. Consistently normal levels of AT III (greater than 80%) were found despite evidence of intravascular coagulation. However, plasma levels of anti-Xa were often low (less than 70%) and increased only in the presence of heparin. The significance of these results in relationship to heparin therapy for disseminated intravascular coagulation of APL is discussed.

Adolescent↗
PubMed1983

Antithrombin III and anti-activated factor X activity in patients with acute promyelocytic leukemia and disseminated intravascular coagulation treated with heparin.

Two patients diagnosed as having acute promyelocytic leukemia (APL) and disseminated intravascular coagulation (DIC) were closely followed from the day of admission until completion of the first course of chemotherapy with serial coagulation studies including plasma levels of functional antithrombin III activity (AT III) by fluorometric analysis and anti-activated Factor X activity (anti-Xa) by coagulation assay. Both patients were treated with intravenous heparin and the presence of heparin in plasma was followed by the thrombin time. Consistently normal levels of AT III (greater than 80%) were found despite evidence of intravascular coagulation. However, plasma levels of anti-Xa were often low (less than 70%) and increased only in the presence of heparin. The significance of these results in relationship to heparin therapy for disseminated intravascular coagulation of APL is discussed.

Adolescent↗
PubMed1984

Tamoxifen treatment of metastatic breast cancer and antithrombin III levels.

Reported in the literature are several cases of thromboembolic complications occurring in patients on tamoxifen citrate for metastatic breast cancer. In view of this literature, a study of patients on tamoxifen was initiated to determine if a paradoxical estrogenic effect was present as evidenced by lowered levels of antithrombin III (AT III). Both functional and immunologic levels were assayed. Twenty-four women with metastatic breast cancer (predominantly bone, 83%) on tamoxifen 10 mg by mouth twice daily were studied. The mean duration of tamoxifen therapy at the time of the AT III determination was 36 weeks (range, 2-87 weeks). The mean age of the group was 64 years with a mean functional AT III of 86% (normal, 82%-120%). Ten of 24 (42%) had low levels of functional AT III (mean, 75%), whereas, the remaining 14 (58%) had normal levels of functional AT III (mean, 94%). Immunologic AT III levels were normal in 23 patients (mean, 26 mg/dl; normal range, 17-30 mg/dl) and elevated in 1 patient. Similarly, functional and immunologic AT III levels were determined in 11 women with metastatic breast cancer on no hormonal therapy. One of 11 (9%) had a low level of functional AT III with a mean of 102% for the entire group. The mean immunologic AT III was 28 mg/dl with two elevated. The poor correlation between functional and immunologic AT III levels may be similar to the disparity noted in women using estrogen-containing oral contraceptives. The finding of lowered functional activity of AT III in 42% of tamoxifen-treated patients is preliminary in nature and will require larger confirmatory studies, including further clinical correlation of this observation.

Antithrombin III↗
PubMed1985

Thromboembolic complications associated with L-asparaginase therapy. Etiologic role of low antithrombin III and plasminogen levels and therapeutic correction by fresh frozen plasma.

A case of an 18-year-old woman with acute lymphoblastic leukemia who developed L-asparaginase-associated stroke and subclavian vein thrombosis is presented. The latter was also associated with a Hickman central venous catheter. Thrombotic complications occurred when plasma levels of plasminogen and antithrombin III were still markedly reduced as a result of L-asparaginase therapy, although the fibrinogen had recovered from its lower levels. The stroke was treated with fresh frozen plasma and the subclavian vein thrombosis was treated with streptokinase and fresh frozen plasma. L-asparaginase and Hickman-associated coagulopathy is reviewed and the treatment is discussed.

Adolescent↗
PubMed2004

Molecular basis of inherited antithrombin deficiency in Portuguese families: identification of genetic alterations and screening for additional thrombotic risk factors.

Antithrombin (AT), the most important coagulation serine proteases inhibitor, plays an important role in maintaining the hemostatic balance. Inherited AT deficiency, mainly characterized by predisposition to recurrent venous thromboembolism, is transmitted in an autosomal dominant manner. In this study, we analyzed the underlying genetic alterations in 12 unrelated Portuguese thrombophilic families with AT deficiency. At the same time, the modulating effect of the FV Leiden mutation, PT 20210A, PAI-1 4G, and MTHFR 677T allelic variants, on the thrombotic risk of AT deficient patients was also evaluated. Three novel frameshift alterations, a 4-bp deletion in exon 4 and two 1-bp insertions in exon 6, were identified in six unrelated type I AT deficient families. A novel missense mutation in exon 3a, which changes the highly conserved F147 residue, and a novel splice site mutation in the invariant acceptor AG dinucleotide of intron 2 were also identified in unrelated type I AT deficient families. In addition to these, two previously reported missense mutations changing the AT reactive site bond (R393-S394) and leading to type II-RS deficiency, and a previously reported cryptic splice site mutation (IVS4-14G-->A), were also identified. In these families, increased thrombotic risk associated with co-inheritance of the FV Leiden mutation and of the PAI-1 4G variant was also observed. In conclusion, we present the first data regarding the underlying genetic alterations in Portuguese thrombophilic families with AT deficiency, and confirm that the FV Leiden mutation and probably the PAI-1 4G variant represent additional thrombotic risk factors in these families.

Amino Acid Sequence↗
PubMed1987

Spontaneous antithrombin in a patient with benign paraprotein.

A 66-year-old man with peptic ulcer disease developed a paraprotein that resulted in a spontaneously prolonged prothrombin time, activated partial thromboplastin time, and thrombin clotting time. Although the reptilase time was normal, the thrombin clotting time failed to correct with the addition of normal plasma, calcium, or protamine sulfate. The patient's purified fibrinogen was normal, but his serum contained an IgG that inhibited the clotting of normal plasma and purified fibrinogen in the presence of thrombin. In contrast to previously described paraproteins, this patient's IgG appeared to inhibit the activity of thrombin per se rather than to interfere with fibrinogen cleavage or fibrin polymerization. Although immunoprecipitation between thrombin and the paraprotein could not be demonstrated, the patient's purified IgG, in the presence of thrombin, decreased the thrombin activity on a chromogenic substrate. Further, increasing concentrations of thrombin overcame the inhibitory effect of the patient's paraprotein. Thus, the patient's paraprotein appeared to possess antithrombin activity.

Aged↗
PubMed1988

Cerebral thrombosis in a newborn with a congenital deficiency of antithrombin III.

An Israeli Arab family with type I antithrombin III (AT-III) deficiency with several affected symptomatic members in three generations is reported. The propositus presented with deep vein thrombosis and pulmonary emboli associated with gestation. The propositus infant presented at the age of 2 weeks with superior sagittal and rectus sinus thrombosis. Hereditary AT-III deficiency should be considered in infants with cerebral thrombosis, especially if they have a family history of thromboembolism. The role of prophylactic therapy by AT-III concentrates in these infants should be further assessed.

Adult↗
PubMed1994

Prevalence of antithrombin deficiency in healthy blood donors: a cross-sectional study.

The prevalence of antithrombin (AT) deficiency in the general population has been variously estimated to be between 0.05 and 5 per 1,000 in the population; 2,491 blood donors were screened in an attempt to clarify this issue using plasma samples taken from the blood donor units. From this initial population, 122 individuals were identified as having plasma AT levels lower than 2 standard deviations below the normal mean. Twenty-two samples had evidence that thrombin had been generated during blood collection and the remaining cohort of 100 blood donors were asked to return but only 59 complied. The data obtained from these 59 were compared with that from 51 age- and sex-matched control blood donors. Both groups of subjects were assessed for previous evidence, or family history, of thrombotic events, as well as exposure to risk factors associated with the development of deep vein thrombosis (DVT). All had venous blood samples taken from which the supernatant plasma was immediately removed and quick frozen for later assaying. Only 6 of the 59 subjects with initial low AT levels had repeat AT-Xa levels below 0.80 units/ml (normal range 0.94 +/- 0.14). Upon repeating the AT-Xa determinations on new samples from these six individuals, only three were found again to be low. One was found to have a type 3 AT deficiency (an Arg47Cys substitution). The other two with a low AT level had mean functional AT-Xa levels of 0.61 and 0.71 units/ml, respectively, with correspondingly low AT:Ag levels consistent with a type 1 AT deficiency. Two of these three subjects has been in high risk situations without evidence of having developed DVT and none had evidence of venous reflux on Doppler venography. In addition, none had personal or family histories of previous thrombotic events. These present data indicate that the prevalence of AT deficiency in our blood donor population is 2 per 1,000 (95% confidence intervals: 0.7-6/1,000).

Antithrombins↗
PubMed2001

A patient defines the interstitial 1q deletion syndrome characterized by antithrombin III deficiency.

A patient with microbrachycephaly, high forehead, long philtrum, thin upper lip, downturned corners of the mouth, low set ears with overlapping helix, fifth-finger clinodactyly, small hands and feet, bilateral transverse palmar crease, low total finger ridge count, hypotonia, severe growth and psychomotor delay, mild hypoplasia of corpus callosum, and Arnold-Chiari type 1 malformation is reported. The karyotype showed 46, XY, del(1)(q23q31.2). Coagulation factor V (F5, 1q23) and coagulation factor XIII (F13B, 1q31-q32.1) levels were normal. As expected, antithrombin III (AT3, 1q23-q25.1) serum level and activity were half of normal. We performed a review of the literature on proximal and intermediate deletion 1q syndrome, and we hypothesize the existence of only one 1q interstitial deletion syndrome, clinically characterized by ATIII deficiency.

Adolescent↗
PubMed1990

Location of disulfide bonds in antithrombin III.

Proteolytic digests of human antithrombin III (ATIII) have been analyzed by a combination of reversed-phase high-performance liquid chromatography and fast atom bombardment (FAB) mass spectrometry for disulfide-containing peptides which are diagnostic for disulfide linkages in ATIII. These results indicate that disulfide bonds join Cys 8 and Cys 128, Cys 21 and Cys 95, and Cys 247 and Cys 430. In addition, these results demonstrate that systematic searches of the amino acid sequence of a large protein for segments with molecular weights matching FAB mass spectral information is a viable method for identifying peptides independent of the specificity of the enzyme used to fragment the protein.

Antithrombin III↗
PubMed2006

Successful anticoagulation with bivalirudin in antithrombin-deficient pediatric patient undergoing stent placement.

Many pediatric patients requiring anticoagulation during interventional heart catheterizations have antithrombin (AT) deficiency. AT is a necessary cofactor for heparin inhibition of thrombin. Without sufficient AT, these patients are at increased risk for thrombotic complications. This case describes the successful use of bivalirudin, a direct thrombin inhibitor, as an anticoagulant in a 2-month old infant with AT deficiency undergoing stent placement.

Anticoagulants↗
PubMed2003

Characterization of antithrombin III from human plasma by two-dimensional gel electrophoresis and capillary electrophoretic methods.

The isoforms distribution of the glycoprotein antithrombin III (ATIII) derived from human plasma was investigated by means of isoelectric focusing (IEF) in polyacrylamide gels with immobilized pH gradients (IPG) and two-dimensional gel electrophoresis (2-DE) as well as capillary electrophoretic methods. It turned out that the presence of high concentrations of chaotropics (urea, thiourea) and zwitterionic detergents (3-[(3-cholamidepropyl)dimethylammonio]-1-propanesulfonate (CHAPS)) was decisive for attaining good resolution of the protein isoforms. Resolution by IPG-IEF was obtained with excellent reproducibility and pI differences down to 0.01 pH units could be distinguished. ATIII-alpha and ATIII-beta-fractions preseparated by heparin affinity chromatography showed an analogous but shifted spot pattern consisting each of one major and three minor isoforms. The main isoforms of ATIII-alpha and ATIII-beta exhibit pI values of 5.18 and 5.32, respectively, both values determined in the presence of high concentrations of urea. The pI difference of 0.14 pH units correspond to the effect of two sialic acids absent in ATIII-beta. The formation and occurrence of ATIII dimers and trimers turned out to be dependent on the sample preparation. The results obtained by 2-DE were compared with those of capillary zone electrophoresis (CZE) and capillary IEF (CIEF). Quantitative analysis regarding the CZE separated isoforms of plasma derived ATIII yielded a content of about 70% ATIII-alpha main isoform and about 6.6% of ATIII-beta. The pI values of ATIII determined by CIEF with internal calibration were in fair agreement with the pI values of the main isoforms achieved with 2-DE.

Antithrombin III↗