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PubMedDate not supplied

Protective effects of antithrombin III on retinal ischemia/reperfusion injury in rats: a histopathologic study.

PURPOSE: To investigate the effect of antithrombin III (AT III) on retinal ischemia/reperfusion (I/R) injury in rats. METHODS: The study was carried out on 10 Wistar albino rats (20 eyes) and four-vessel occlusion method was employed to induce retinal ischemia in this study. Rats were divided into two groups: Group I (control group, 10 eyes) and Group II (AT III, 10 eyes). In both groups, vertebral arteries were occluded bilaterally an electric needle coagulator under an operating microscope. A total of 48 hours after the initial procedure, the rats were re-anesthetized and both common carotid arteries were clamped to interrupt blood flow. In Group II, rats were injected intravenously with 250 U/kg of AT III 5 minutes before the induction of ischemia. Duration of ischemia was 30 minutes. At the end of this period, clamp was removed for the reperfusion of the eye for 4 hours. Following the reperfusion period, the animals were killed by decapitation. Retinal sections were evaluated under light and electron microscope. The signs of I/R injury at the microscopic level, i.e., cellular degeneration, vacuolization between retinal layers, increase in the retinal thickness due to edema, mononuclear cell infiltration, and apoptotic cells, were recorded for each group. RESULTS: Retinal sections obtained from the rats in the AT III group revealed a well preserved retinal structure. When average thickness values of the two groups were compared to each other, the difference was significant with respect to inner nuclear and inner plexiform layers indicating increased retinal thickness values in Group I due to tissue edema resulting from I/R injury. Similarly, mononuclear cell infiltration and apoptotic cell counts were found to be significantly higher in control group compared to AT III group showing the inhibitory effect of AT III on leukocyte infiltration and apoptotic cell death in rat retina. CONCLUSIONS: Antithrombin III attenuated I/R injury in rat retina.

Animals↗
PubMed2006

Biodistribution of covalent antithrombin-heparin complexes.

We have developed a covalent antithrombin-heparin (ATH) complex with advantages compared to non-covalent antithrombin:heparin (AT:H) mixtures. In addition to increased activity, ATH has a longer intravenous half-life that is partly due to reduced plasma protein binding. Given ATH's altered clearance, we investigated biodistribution of ATH in vivo. ATH made from either human plasma-derived AT (pATH) or recombinant human (produced in goats) AT (rhATH) was studied. 125I-ATH + unlabeled carrier was injected into rabbits at different doses. 131I-labeled albumin was administered just before sacrifice as a marker for trapped blood in tissues. Immediately after sacrifice, animal components were removed, weighed, and subsamples were counted for gamma-radioactivity. Percent recoveries of ATH in various organs/compartments at different time points were calculated, and kinetic distribution plots generated. At saturating doses, early disappearance of rhATH from the circulation was much faster than pATH. Co-incident with clearance, 26 +/- 3% of dose for rhATH was liver-associated compared to only 3.7 +/- 0.5% for pATH by 20 min. Also, at early time periods, >60% of all extravascular ATH was liver-associated. Analysis of the vena cava and aorta suggested that vessel wall binding might also account for initial plasma loss of rhATH. By 24 h, most of pATH and rhATH were present as urinary degradation products (51 +/- 3% and 63 +/- 8%, respectively). In summary, systemic elimination of ATH is greatly influenced by the form of AT in the complex, with liver uptake and degradation playing a major role.

Animals↗
PubMed2005

[A heterozygous point mutation G13328A in antithrombin gene causes thrombosis].

OBJECTIVE: To identify the phenotype and the gene mutation in a kindred with antithrombin (AT) deficiency. METHODS: Immuno-nephelometry and chromogenic assay were used to detect the plasma level of AT antigen (AT: Ag) and activity (AT: A), respectively. All the seven exons and intron-exon boundaries of AT gene from the propositus were amplified by PCR and direct sequencing of the PCR pro-ducts was performed. Corresponding PCR fragments from the kindred were also sequenced directly. Megaprimer method was used to construct the mutant AT cDNA expressing vector from normal plasmid pCRII AT cDNA. The normal and mutant AT plasmid were transiently transfected into Cos-7 cells and AT: Ag was detected in supernatant and lysate of transfected cell with ELISA. RESULTS: The plasma level of AT: Ag and AT: A for the propositus were 179 mg/L and 42.3%, respectively. A heterozygous G13328A missense mutation in exon 6 was identified, which led to the substitution of Thr (ACC) 404 for Ala (GCC). The sequencing results from the pedigree suggested that three other members also had the mutation. The level of AT:Ag in supernatant and lysate from cells transfected with mutant AT cDNA was 40% and 68% of that of normal AT cDNA transfected cells. CONCLUSION: This is an unreported AT gene mutation in China, which causes type I hereditary antithrombin deficiency and thrombosis in the proposita.

Antithrombins↗
PubMed2006

Detection of heterozygous large deletions in the antithrombin gene using multiplex polymerase chain reaction and denatured high performance liquid chromatography.

The present study reports a method for the easy, rapid and cost effective detection of heterozygous large deletions. As a model gene all exons of the antithrombin gene were amplified in a one tube multiplex polymerase chain reaction (PCR) and the products separated according to their size by reverse-phase ion-pair high performance liquid chromatography. A significant reduction in the height of a peak in the probandOs sample compared to in the control indicates the presence of a large deletion of the corresponding allele. Using this approach we identified heterozygous deletions in four patients: the deletions affected exons 1 and 2, exon 7 and the whole antithrombin gene.

Antithrombin III↗
PubMed1990

Fluctuation of thrombin-antithrombin III complex in patients with acute myocardial infarction: influence of low-dose heparin administration.

The haemostatic parameters were studied within 14 days of acute myocardial infarction (AMI) in 103 patients randomly allocated into a group receiving low-dose heparin or into a group treated without anticoagulants. Patients with isotopic evidence of deep vein thrombosis were excluded from the analysis. An important formation of thrombin-antithrombin III complex (TAT) in the plasma was detected in the early stage of the disease. It was accompanied by an activation of plasma intrinsic fibrinolysis (IF), an elevation of fibrinogen and its degradation products (FDP) and a reduction of extrinsic plasma fibrinolytic activity (EF) together with normal levels of factor X, antithrombin III (AT III), protein C and alpha-2-antiplasmin. Sequentially studies periods of the disease revealed a diminution of TAT complex concentration in the plasma on the seventh day of AMI together with a rise of the both plasma fibrinolytic activities (IF, EF) as well as an elevation of fibrinogen and its degradation products, returning to the initial values on the 14 day of AMI. In the patients treated with heparin the augmentation of TAT complex in the plasma was prolonged until the fifth day of AMI. Moreover, heparin administration was connected with significantly higher levels of AT III and protein C along with a lower concentration of factor X and FDP on the seventh day of the disease. The fluctuation of fibrinolytic activities (IF, EF) in the plasma was heparin-independent. The present results indicate that low-dose heparin treatment modulates the plasmatic fluctuation of TAT complex as well as factor X, AT III and protein C levels in patients with acute myocardial infarction.

Antithrombin III↗
PubMed1990

[A method of determining heparin in blood plasma based on its antithrombin activity].

The suggested method for measuring blood plasma heparin is based on heparin ability to enhance antithrombin activity of antithrombin III (AT-III), the major Xa and thrombin inhibitor. The method consists in measurement of blood plasma AT-III activity in the presence and absence of protamine sulfate that destroys the heparin--AT-III complex. Heparin content in U/ml is determined from the difference in the activities of heparin--AT-III complex and AT-III proper activity represented on the calibration curve. The method is sufficiently sensitive, it permits registration of heparin concentrations in a wide band (from 0.01 U/ml to 0.75 U/ml of plasma).

Antithrombin III↗
PubMed1992

Search for the heparin antithrombin III-binding site precursor.

The last step of heparin biosynthesis is thought to involve the action of 3-O-sulfotransferase resulting in the formation of an antithrombin III (ATIII) binding site required for heparin's anticoagulant activity. The isolation of a significant fraction of heparin chains without antithrombin III-binding sites and having low affinity for ATIII suggests the presence of a precursor site, lacking the 3-O-sulfate group. Porcine mucosal heparin was depolymerized into a mixture of oligosaccharides using heparin lyase. One of these oligosaccharides was derived from heparin's ATIII-binding site. In an effort to find the ATIII-binding site precursor, the structures of several minor oligosaccharides were determined. A greater than 90% recovery of oligosaccharides (on a mole and weight basis) was obtained for both unfractionated and affinity-fractionated heparins. An oligosaccharide arising from the ATIII-binding site precursor was found that comprised only 0.8 mol % of the oligosaccharide product mixture. This oligosaccharide was only slightly enriched in heparin having a low affinity for ATIII and only slightly disenriched in high affinity heparin. The small number of these ATIII-binding site precursors, found in unfractionated and fractionated heparins, suggests the existence of a low ATIII affinity heparin may not simply be the result of the incomplete action of 3-O-sulfotransferase in the final step in heparin biosynthesis. Rather these data suggest that some earlier step, involved in the formation of placement of these precursor sites, may be primarily responsible for high and low ATIII affinity heparins.

Animals↗
PubMed1992

Antithrombin III level, fibrinogen level, and platelet count changes with adjuvant tamoxifen therapy.

Adjuvant therapy for breast cancer with tamoxifen is suggested to be of benefit to both women with negative and women with positive axillary nodes, and treatment lasting several years is currently being investigated. Venous thrombophlebitis may complicate tamoxifen treatment at a rate of approximately one per 800 treatment-years. To explore the possible mechanisms of this effect, we evaluated changes in antithrombin III levels, fibrinogen levels, and platelet counts in 140 postmenopausal women with surgically resected breast cancer who were disease free and participating in a double-blind, placebo-controlled, randomized toxicity study of tamoxifen. Antithrombin III levels, elevated at baseline evaluation, decreased in tamoxifen-treated subjects at 6 months, but no subject exhibited a drop to clinically significant levels. Fibrinogen levels decreased 15% (0.4 g/L) in tamoxifen-treated subjects at 6 months. Platelet counts decreased 7% to 9% from baseline to evaluations at 3, 6, 12, 18, and 24 months in tamoxifen-treated subjects. While these changes do not explain the possible small thrombophlebitis-promoting effect of tamoxifen, the decrease in fibrinogen levels might be expected to be associated with a decreased risk of arterial thrombosis.

Antithrombin III↗
PubMed1991

[Concentration of thrombin antithrombin III complex and plasmin alpha 2-plasmin inhibitor complex in nephrotic syndrome].

Plasma concentration of fibrinogen (Fbg), plasminogen (PLG), antithrombin III (AT III), alpha 2-plasmin inhibitor (alpha 2-PI), thrombin antithrombin III complex (TAT) and plasmin alpha 2-plasmin inhibitor complex (PIC) were evaluated in 23 nephrotic patients with proteinuria more than 3.5 g/day, including 4 cases with clinical evidence of thromboembolism. Among patients without thromboembolism, concentration of PLG and AT III was in the normal range but that of Fbg and alpha 2-PI was significantly elevated (p less than 0.01 for Fbg and p less than 0.001 for alpha 2-PI respectively). Also there was a positive relationship between AT III and serum albumin (p less than 0.05). Two fifth of these patients had an had an increased level of TAT, and also had a higher level of PIC compared with normal control (p less than 0.01). There was a positive relationship between TAT and PIC, TAT and Fbg (p less than 0.05), PIC and Fbg (p less than 0.01). TAT and PIC levels were markedly elevated in the patients with thromboembolism. From aforementioned data, it was suggested that patients with nephrotic syndrome would be in the prethrombotic state and the increased level of Fbg is one of the major risk factors of thromboembolic complications in these patients. Furthermore measurement of TAT and PIC are the useful means for the diagnosis of these complications.

Adolescent↗
PubMed1991

Activated factor IX-antithrombin III complexes in human blood: quantification by an enzyme-linked differential antibody immunoassay and determination of the in vivo half-life.

An enzyme-linked immunoassay has been developed to quantitate the activated human factor IX-antithrombin III complex (IXa-AT III). Test plasma was absorbed onto barium citrate and eluted to remove free antithrombin III (AT III). The IXa-AT III complex in the eluate was then measured by using polystyrene balls coated with immobilized rabbit anti-AT III antibody-binding fragments and anti-factor IX (anti-FIX) antibody-binding fragments labeled with beta-D-galactosidase. The assay was very sensitive, detecting a concentration as low as 0.15 fmol/assay/100 microliters plasma, which corresponds to as little as 0.002% of activated FIX in plasma. Experiments with purified FIX, IXa-alpha, AT III, IXa-AT III, normal plasma, AT III-depleted plasma, and FIX-deficient plasma demonstrated that the assay is specific. IXa-AT III generation could be detected in normal native whole blood within 2.0 minutes after venipuncture. The complex could not be detected in native whole blood from patients with severe hemophilia B even at 1 hour after venipuncture. The mean plasma level of IXa-AT III in healthy adults (n = 32, ages 23 to 54 years) was 9.67 +/- 2.86 pmol/L (mean +/- SD), whereas in eight patients with disseminated intravascular coagulation levels ranged from 11.7 to 35.0 pmol/L. The IXa-AT III titer was significantly reduced in three patients with severe factor VII deficiency (5.70 +/- 1.99 pmol/L) but was normal in three patients with severe factor XI deficiency (11.2 +/- 1.59 pmol/L). Purified IXa-AT III was cleared in vivo in rabbits with a half-life value of 30 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Expression of biologically active human antithrombin III by recombinant baculovirus in Spodoptera frugiperda cells.

Antithrombin III (ATIII) is a plasma-borne serine protease inhibitor that plays a pivotal role in the regulation of hemostasis. The cDNA for ATIII has been available, but genetic studies on the functional domains of ATIII have not progressed because of the absence of an expression system that will yield sufficient quantities of biologically active protein for biochemical analyses. In the present studies the cDNA of the human antithrombin III gene was inserted into the vector pVL 1393, which is suitable for cotransfection of Spodoptera frugiperda (Sf9) insect cells with Baculovirus wild-type DNA. Recombinant virus particles were selected by the presence of occlusion-negative plaques. Upon infection with purified recombinant virus, Sf9 cells secreted 10-35 micrograms of ATIII/1 x 10(6) cells. Southern analysis of DNA from infected cells demonstrated incorporation of the full-length cDNA into the Baculovirus recombinant, and RNase protection experiments verified the presence of full-length transcript. This recombinant ATIII protein was immunologically reactive with antisera raised against native human ATIII, formed stable complexes with thrombin, and was heparin-accelerated at the same concentration as native human ATIII. In addition, the recombinant ATIII retained specificity for the same molecular species of heparin that activates authentic human ATIII. This is the first successful production of active, recombinant ATIII in quantities that will allow purification on the milligram scale and permit a biochemical analysis of genetically engineered variants.

Amino Acid Sequence↗
PubMed1990

Development of MDL 28,050, a small stable antithrombin agent based on a functional domain of the leech protein, hirudin.

MDL 28,050 is a decapeptide antithrombin agent that inhibits alpha-thrombin-induced fibrin clot formation by binding to a non-catalytic site on alpha-thrombin. It is the result of chemical and structural optimization of a functional domain of the leech anticoagulant, hirudin. In contrast to the contention that the polyanionic nature of this C-terminal functional domain governs its interaction with alpha-thrombin, systematic study of this region has shown the importance of the lipophilic residues for providing the functionality necessary for potent binding to alpha-thrombin. The development of MDL 28,050 and other effective antithrombin agents are outlined through the description of the structure-activity relationships (SAR) for these peptides. These peptides are effective in a variety of in vitro and in vivo models of thrombosis.

Amino Acid Sequence↗
PubMed1990

Blood coagulation after long distance running: antithrombin III prevents fibrin formation.

Physical exercise causes shortening of activated partial thromboplastin time (aPTT) and euglobulin clot lysis time. To investigate whether this activation of coagulation and fibrinolysis leads to in vivo thrombin or plasmin action after long distance running, 19 well trained male runners (36-65 years) were examined 5 to 53 min after termination of a 100 km race and 5 days later after at least 1 day without physical exercise. Compared to the control examination aPTT was decreased (30.2 +/- 2.8 vs 35.3 +/- 3.0 sec) and the following parameters were increased after the race: beta thromboglobulin (40 +/- 16 vs 23 +/- 7 ng/ml), thrombin-antithrombin III (TAT) complexes (5.5 +/- 3.4 vs 2.3 +/- 0.7 microgram/l), the fibrin(ogen) degradation products fragment E (57 +/- 15 vs 35 +/- 7 ng/ml) and B beta 15-42 (8.5 +/- 2.5 vs 6.5 +/- 2.5 ng/ml) (all p values less than 0.001). Platelet count, platelet factor 4, fibrinoepetide A (FPA) and haematocrit did not change significantly. Increased TAT complexes and unchanged FPA suggest that the generated thrombin was fully inactivated by antithrombin III (AT III) and did therefore not give rise to fibrin formation. The small increase of fibrin(ogen) degradation products indicates a minor in vivo activity of the fibrinolytic system. This investigation demonstrates the importance of AT III in the regulation of haemostasis in activated blood coagulation.

Adult↗
PubMed1988

Influence of hirudin on the consumption of antithrombin III in experimental DIC.

The effect of hirudin and heparin on thrombin-induced consumption of antithrombin III, fibrinogen and platelets was studied in a rat model. Antithrombin III is consumed by tolerated thrombin doses by about 20 per cent. Hirudin and heparin ameliorate the consumption of fibrinogen and platelets at the low thrombin dose used. At high thrombin doses, tolerated only during simultaneous administration of exogenous inhibitors, heparin leads to markedly increased consumption of anti-thrombin III, whereas hirudin does not. With either kind of treatment, the thrombin effect on fibrinogen and platelets is inhibited, however, hirudin acts independently of a cofactor in contrast to heparin.

Animals↗
PubMed1989

[A kinetic micromethod of determining the activity of antithrombin III].

A method for measuring the blood plasma antithrombin III (AT III) activity is suggested, based on measurement of the rate of inactivation of added standard volume (0.05 ml) of plasma thrombin AT III. The thrombin residual activity in the mixture is detectable over the course of fibrinogen tests. Curves are plotted, reflecting the rate of inactivation of thrombin AT III in the tested and reference plasma samples; by modeling and comparing these curves the values of the examined sample AT III activity are obtained, with the effects of fibrinogen and fast antithrombins various levels eliminated.

Antithrombin III↗
PubMed1989

[Congenital type I antithrombin III deficiency with serious complications in a 7-year-old girl].

This case report concerns a child admitted to the County Hospital of Zalaegerszeg with the symptoms of ataxia, focal convulsions and hemiparesis. Anticonvulsive therapy abolished the epileptic manifestations, but hemiparesis remained unchanged. At the age of six and half years progressive venous thrombosis developed first on the left and some days later on the right lower limb. Phlebography revealed on both sides thrombosis of the vena iliaca which led to stenosis of the right femoral vein and dilated venous collaterals on the abdomen and right thigh. Coeliacography showed an enlarged spleen and varicosity around the portal vein. Later thrombosis of the arteria dorsalis pedis developed indicated by the gangrene the fifth toe. At this stage the child was transfered to the Pediatric Department of the University of Pécs for further evaluation. Examination of the hemostasis showed hypercoagulability due to antithrombin III deficiency pointing towards a common cause, namely thromboembolism of the earlier and recent clinical manifestations. A reduced activity of the antithrombin III was also observed in the mother and two sisters of the child. The response to Syncumar therapy was beneficial, arterial thrombosis regressed and no further thromboembolic complications developed.

Acenocoumarol↗
PubMed1989

Heparin binding domain of human antithrombin III inferred from the sequential reduction of its three disulfide linkages. An efficient method for structural analysis of partially reduced proteins.

Human antithrombin III (AT-III) was partially reduced under mild conditions in the absence or presence of low molecular weight heparin. Quantitation of reduced disulfide bonds was facilitated by the application of a water-soluble color reagent, 4-N,N-dimethylaminoazobenzene-4'-iodoacetamido-2'-sulfonic acid (S-DABIA). The study shows that the three disulfide linkages of AT-III can be sequentially reduced, with Cys8-Cys128 being the most sensitive, followed by Cys21-Cys95, while Cys247-Cys430 is the most resistant to the mild reduction conditions. The rate of reduction of Cys8-Cys128 and Cys21-Cys95 was significantly decreased in the presence of heparin. The reduction of Cys8-Cys128 was also found to correlate quantitatively with the loss of heparin-accelerated antithrombin activity, heparin binding affinity, and heparin-induced fluorescence enhancement. These results suggest that Cys8-Cys128 is required for the integrity of the heparin binding domain of AT-III and support previous findings that lysyl residues surrounding Cys128 (Lys107, Lys114, Lys125, and Lys136) constitute an important part of the heparin binding site in AT-III.

Alkylation↗
PubMed1989

Thrombin-antithrombin III complexes in the prediction of deep vein thrombosis following total hip replacement.

In 196 consecutive patients who underwent elective total hip surgery we investigated the diagnostic accuracy of the thrombin-antithrombin III complex immunoassay, as assessed on the first, fourth and tenth postoperative day, for the development of deep vein thrombosis (DVT). Patients received either LMW-heparinoid (n = 97) or placebo (n = 99) and underwent contrast venography on the tenth postoperative day. Thrombin-antithrombin III (T-AT) plasma levels were raised in all patients on the first postoperative day and gradually decreased during the study period. T-AT plasma levels were significantly higher in patients developing DVT when compared to patients without DVT and remained so until day 10. This difference was apparent both in the LMW-heparinoid group as well as in the placebo-treated patients. ROC-curve analysis revealed no satisfactory discriminative power for the diagnosis of developing DVT at any of the studied cut-off values for T-AT. We conclude that the postoperative determination of T-AT complex plasma concentrations in hip surgery patients has no clinical utility in the prediction of postoperative DVT.

Antithrombin III↗