The effect of low-dose heparin on fibrinopeptide A, platelets, fibrinogen degradation products and other haemostatic parameters measured in connection with intestinal surgery

Fibrinopeptide A (FPA), fibrinogen degradation products (FDP), platelets and other coagulation parameters were measured in 17 surgical patients pre- and postoperatively in a controlled, randomised study. Nine patients received calcium heparin 5000 IU subcutaneously every 8 hours for 7 days, the first injection given 2 hours preoperatively. Eight control patients received 5% glucose only. The groups were comparable. Significantly lower levels of FPA were demonstrated postoperatively in the heparin group during and after low-dose heparin treatment. There was a significant correlation between simultaneous determinations of heparin and FPA levels in the patients receiving low-dose heparin, while no significant difference was found in the other parameters. The results indicate reduced thrombin activity postoperatively in patients receiving low-dose heparin.     

Factors with conformational effects on haemostatic serpins: implications in thrombosis

Serpins are key actors of systems involving proteolytic reactions, such as the haemostatic system, as they are irreversible suicide inhibitors of serine proteases. The structural flexibility and physical properties of serpins that are required for their efficient inhibitory mechanism also make them especially vulnerable to even minor factors that induce conformational changes in the native form of these molecules, leading to a number of inactive conformations, such as latent, cleaved or polymers. Increasing numbers of conformational mutations affecting haemostatic serpins, mainly antithrombin, the main endogenous anticoagulant, have been described. These mutations cause circulating deficiencies of the molecules, in most cases due to intracellular retention, which may be associated with a hyper-coagulable state. Indeed, conformational mutations in antithrombin have been identified in patients with severe venous thrombosis, which has led to the hypothesis that these disorders might be included in the group of conformational diseases. Moreover, we have recently demonstrated that other factors, including both drugs, such as the treatment with L-asparaginase, or environmental factors, such as high temperatures or hyperlipidemia, may also have conformational consequences on hepatic antithrombin, thus resulting in intracellular aggregation and plasma deficiency, which may increase the risk of thrombosis. In this study, we review the causes of deficiency of haemostatic serpins that may be explained by conformational mechanisms, and their association with an increased risk of venous thrombosis.     

Fetal fibrinogen and fibrinogen Paris I: Comparative fibrin monomers aggregation studies

Comparative studies have demonstrated that in human cord the conversion of fibrinogen to fibrin by thrombin led to the appearance of fibrin monomers that had an aggregation profile that differed from the adult. The aggregation rate and the final recorded absorbance were respectively slower and lower for the cord fibrin monomers. The action of thrombin on fibrinogen derived from bovine fetus led to the appearance of fibrin monomers that had the same characteristics described for human cord monomers. In addition two different features were observed: the monomers had an inhibitory effect on the aggregation of cow monomers and a second population “soluble fibrin monomers” was observed. Whether these differences were related to species specificity or to the degree of gestation is not known. The study of the congenital and inherited fibrinogen Paris I showed that the aggregation step of the fibrinogen to fibrin conversion was abnormal. In addition the fibrin monomers had an inhibitory effect on the aggregation of normal fibrin monomers and, a second population “soluble fibrin monomers” was observed. The fact that the same observations were made while studying the aggregation of bovine fetus fibrin monomers and the abnormal fibrinogen Paris I may be fortuitous. It may also allow to raise the question whether or not some cases of abnormal fibrinogen are related to the persistance of fetal fibrinogen. Biochemical data would still be necessary to sustain such a hypothesis.     

APC resistance and other haemostatic variables during pregnancy and puerperium

Forty-eight healthy pregnant women were studied prospectively and longitudinally. Blood sampling was performed at 10-15, 23-25, 32-34 and 38-40 weeks of gestation, within one week and at eight weeks postpartum. Classic and modified activated protein C ratio decreased as pregnancy progressed. In the third trimester 92% of the ratios measured with the classic test were above the lower reference level whereas all modified test ratios were normal. Slight activation of blood coagulation was shown with increased levels of prothrombin fragment 1+2, soluble fibrin and D-dimer. Fibrinogen, factor VIII and plasminogen activator inhibitor type I and type 2 increased. Protein S and tissue plasminogen activator activity decreased. Protein C remained unchanged. No correlation was found between the decrease in classic APC ratio and changes in factor VIII, fibrinogen, protein S, prothrombin fragment 1+2 or soluble fibrin, nor between the increase in soluble fibrin and changes in prothrombin fragment 1+2, fibrinogen and D-dimer.     

Plasma haemostatic potential of haemodialysis patients assessed by thrombin generation assay: Hypercoagulability in patients with vascular access thrombosis

Introduction

Patients with end-stage renal disease (ESRD) on maintenance haemodialysis are predisposed to bleeding and thrombotic events. Recently thrombin generation assay (TGA) has been introduced as a laboratory assessment of global haemostatic potential. We investigated the global haemostatic potential assessed by TGA in ESRD patients on haemodialysis and patients who developed vascular access thrombosis.

Materials and Methods

A total of 69 ESRD patients who underwent haemodialysis (58 stable patients and 11 vascular access thrombosis patients) were included and 33 healthy controls were included. TGA was performed on the calibrated automated thrombogram using tissue factor with/without addition of thrombomodulin or activated protein C, producing three parameters including lag time, endogenous thrombin potential (ETP) and peak thrombin.

Results

Haemodialysis patients showed low ETP values measured by thrombin generation assay compared with the healthy controls. Interestingly, patients with vascular access thrombosis exhibited short PT and aPTT and increased resistance of coagulation inhibition to APC anticoagulant protein, reflecting hyper-coagulability. Haemodialysis patients who are taking anti-platelet agents showed decreased thrombin inhibition rate, representing antithrombotic effect of anti-platelet agents.

Conclusion

Whereas the haemodialysis patients showed hypo-coagulability, the patients with vascular access thrombosis exhibited hyper-coagulability. Further study is required to investigate how this haemostatic potential may be utilized to guide the physician to more effective management of haemostatic complication.     

颅内静脉窦血栓形成患者纤维蛋白原D-二聚体与预后的相关性

目的探讨静脉窦血栓形成(CVST)患者纤维蛋白原、D-二聚体与短期预后的关系。方法选取CVST患者56例为CVST组,检测血浆纤维蛋白原、D-二聚体,并与50例健康者(对照组)作对照。按改良Rankin量表(mRS)评分,将CVST患者再分为预后良好组和预后不良组,并对比2组纤维蛋白原、D-二聚体水平。结果静脉窦血栓形成患者组D-D、Fbg分别为(316.37±14.59)ng/mL、(4.96±1.27)g/L,均显著高于对照组;预后良好组D-D、Fbg分别为(289.34±22.37)ng/mL、(4.58±1.16)g/L,均显著低于CVST预后不良组。结论血浆纤维蛋白原、D-二聚体对于CVST的诊断和短期预后判断有重要临床价值。     

Are haemostatic and fibrinolytic parameters predictors of preeclampsia in pregnancy-associated hypertension?

The plasma levels of several haemostatic and fibrinolytic parameters were measured before and after delivery in 61 hypertensive pregnant women of whom 22 developed preeclampsia, and compared to the results obtained in 42 normal pregnant women. In the two last weeks before delivery (D less than or equal to -15) tPA antigen, PAI-1 activity, vWF:Ag/FVIII:C ratio, ATIII activity and platelet count were found to be significantly different in the hypertensive pregnant women with and without preeclampsia. Combined all together, an association of three of these five parameters were found to be pathological (i.e.:tPA:Ag greater than or equal to 19 ng/ml, PAI-1 activity greater than or equal to 58 IU/ml, vWF:Ag/FVIII:C ratio greater than or equal to 2.6, ATIII activity less than or equal to 73%) in none of the hypertensive women without preeclampsia and in only 35% of the preeclamptic group. A positive correlation was demonstrated between vWF:Ag/FVIII:C ratio and tPA:antigen levels suggesting that both tPA and vWF:Ag could be considered as early indicators of a possible micro angiopathy occurring in preeclampsia. However, due to the high dispersion of the results, it appears that the investigated haemostatic and/or fibrinolytic criteria give only presumptive arguments before assigning risk for preeclampsia development among hypertensive pregnant women.     

Cardiac safety parameters of olanzapine: comparison with other atypical and typical antipsychotics

Alterations of electrocardiogram results and cases of sudden cardiac death have been reported since the beginning of neuroleptic treatment. In particular, a temporal association exists between some antipsychotics and prolongation of the heart rate-corrected QT interval (QTc), an event that may increase the risk for developing a potentially fatal ventricular tachycardia arrhythmia known as torsades de pointes if it significantly exceeds normal intraindividual and interindividual variation. Although the incidence of serious adverse cardiac events in response to antipsychotic medications is relatively low, any possibility for the occurrence of cardiotoxicity warrants continued study. The present article reviews important differences among antipsychotic drugs in the potential for, and occurrence of, serious adverse cardiac outcomes and suggests that olanzapine, as therapeutically administered to patients with schizophrenia and related psychoses, does not contribute significantly to a QTc prolongation that could result in potentially fatal ventricular arrhythmias.     

Increased thrombin generation and fibrinogen level after therapeutic plasma transfusion: relation to bleeding

In a clinical setting, fresh frozen plasma (FFP) is transfused to diluted patients with complicated surgery or trauma, as guided by prolonged conventional coagulation times or low fibrinogen levels. However, the limited sensitivity of these coagulation tests may restrict their use in measuring the effect of transfusion and hence predicting the risk of perioperative bleeding. We used the more sensitive, calibrated automated thrombogram (CAT) method to evaluate the result of therapeutic FFP transfusion to 51 patients with dilutional coagulopathy. Thrombin generation was measured in pre- and post-transfusion plasma samples in the presence of either platelets or phospholipids. For all patients, the transfusion led to higher plasma coagulation factor levels, a shortened activated partial thromboplastin time, and a significant increase in thrombin generation (peak height and endogenous thrombin potential). Interestingly, thrombin generation parameters and fibrinogen levels were higher in post-transfusion plasmas from patients who stopped bleeding (n = 32) than for patients with ongoing bleeding (n = 19). Plasmas from 15 of the 19 patients with ongoing bleeding were markedly low in either thrombin generation or fibrinogen level. We conclude that the thrombin generation method detects improved haemostatic activity after plasma transfusion. Furthermore, the data suggest that thrombin generation and fibrinogen are independent determinants of the risk of perioperative bleeding in this patient group.     

Major operations, hemostatic parameters and venous thrombosis

Of 61 patients who underwent elective surgery, 14 (23%) developed deep leg vein thrombosis as diagnozed by the 125 J-fibrinogen test. None of them showed local symptoms suggesting thrombosis. Comparison between the thrombosis and the no thrombosis group failed to show significant differences between the mean levels of FDP, serum and plasma antithrombin III, plasminogen and hematocrit. The fibrinogen concentration was significantly lower in the thrombosis group preoperatively. At later control examinations the thrombosis group had a significantly lower mean α₂-macroglobulin level, but the fibrinolytic capacity was similar in the two groups.One cancer patient, who showed a very marked decrease in antithrombin III level, died with thrombosis of vena cava.     

Changes in haemostatic parameters during the menstrual cycle and subsequent use of drospirenone-containing oral contraceptives

Introduction

Oral contraceptives (OC) increase the risk of venous thromboembolism that depends on the OC formulation and could at least partially be explained by impaired function of the protein C-system (APC resistance) and the tissue factor pathway inhibitor (TFPI)-system. There is limited information available on the effects of OC, containing a newer progestogen- drospirenone (DRSP-OC) on these two major anticoagulant pathways, thrombin generation, reflecting the overall state of coagulation, and other coagulation parameters.

Methods

In a study population consisting of 14 healthy women (age 21–33 years) we investigated the effect of the menstrual cycle and subsequent use of DRSP-OC on APC resistance, the function of the TFPI-system, thrombin generation and on their major determinants, i.e. prothrombin, antithrombin, FV, FX, FVIII, protein C, protein S_{(total and free)} and TFPI_{(full-length and free)}.

Results

All studied parameters remained unchanged during the menstrual cycle. During DRSP-OC use we observed a significant increase in APC resistance (~ 2.4-fold), thrombin generation measured at low (~ 2.2-fold) and high tissue factor concentrations (~ 1.4-fold), plasma concentrations of prothrombin (19%), FX (31%), FVIII (17%) and protein C (43%). DRSP-OC use impaired the function of the TFPI-system and decreased plasma levels of antithrombin (− 6%), FV (− 22%), protein S_total (− 21%), protein S_free (− 20%), TFPI_full-length (− 36%) and TFPI_free (− 46%).

Conclusions

DRSP-OC caused procoagulant changes in all studied haemostatic parameters. The impairment of the protein C- and TFPI-systems was more pronounced than the impairment of the coagulation pathways and can at least partially account for the increased risk of venous thromboembolism in users of DRSP-OC.     

The fibrinogen gamma (FGG) 10034C>T polymorphism is associated with venous thrombosis

INTRODUCTION: Thrombin-induced conversion of fibrinogen to fibrin plays an essential role in hemostasis and results in the stabilization of thrombi. Elevated plasma fibrinogen levels have been associated with both increased plasma viscosity and platelet aggregability. Recently, a haplotype-tagging single nucleotide polymorphism characterized by a C to T substitution at nucleotide 10034 of the fibrinogen gamma gene (FGG 10034C>T, rs2066865), has been proposed as a novel risk factor for deep venous thrombosis (DVT). Aim of the present study was to provide further data on the role of the FGG 10034C>T polymorphism for DVT. MATERIALS AND METHODS: FGG genotypes were determined by 5'-exonuclease assay (TaqMan) in 358 patients with documented DVT and a total of 783 control subjects. RESULTS: In a multivariate analysis adjusting for age, sex, presence of factor V Leiden and carriage of prothrombin 20210A, homozygosity for the FGG 10034 TT genotype yielded an odds ratio of 2.01 (95% CI 1.23-3.31; p=0.006) for DVT. CONCLUSIONS: Our data confirm the primary finding that the FGG 10034C>T polymorphism is associated with DVT risk.     

Fibrinogen Caracas V, an abnormal fibrinogen with an Aalpha 532 Ser-->Cys substitution associated with thrombosis

A new dysfibrinogenemia associated with thrombophilia has been identified in a Venezuelan kindred. Thrombin and Reptilase times were prolonged and the accelerating capacity of the patient's fibrin on the t-PA-induced plasminogen activation was decreased. In addition the affinity of fibrinogen for plasminogen was diminished. Permeability and electron microscopy studies revealed that the abnormal clot was made up of thin and densely packed fibres giving rise to a reduced fibrin gel porosity. This was confirmed by turbidity studies showing a decreased fibre mass/length ratio. Affected members were heterozygous for an Aalpha 532 Ser-->Cys mutation as demonstrated by genetic analyses. This abnormal fibrinogen has been designated as Fibrinogen Caracas V. The family study showed a convincing association between the mutation and thrombotic manifestations. The thrombotic tendency may be ascribed to lack of accelerating capacity of fibrin to induce fibrinolysis caused by an abnormal clot structure with thin fibres and reduced porosity.     

Induction of disseminated intravascular coagulation by endotoxin and saline loading in rats I. The influence on fibrinogen turnover and plasma parameters

In rats a single injection of 1 mg endotoxin and a subsequent infusion of normal saline induced a disseminated intravascular coagulation. A nearly complete defibrination and a decrease of platelets coincided with high amounts of plasma hemoglobin and fibrin/fibrinogen degradation products. Fibrinogen kinetics were investigated by use of 131-I-fibrinogen. The biological half life was 24.1 hours corresponding to a catabolic rate of 78 mg/24h/kg b.w. After triggering the intravascular coagulation the turnover of 131-I-fibrinogen revealed three phases: 1. “acute phase” with a catabolic rate of approx. 780 mg/24h/kg b.w., 2. “subacute phase” with a catabolic rate of 274 mg/24h/kg b.w. and 3. “repair phase” with a catabolic rate approximating to normal values. During the “subacute phase” the fibrinogen level increased above normal, demonstrating that in spite of an increased fibrinogen catabolism due to DIC elevated plasma fibrinogen levels can be found.     

A simplified method for isolation of the S-carboxymethyl derivative chains of normal fibrinogen and fibrinogen cleveland I

Highly purified individual chains of normal fibrinogen and fibrinogen Cleveland I were prepared by chromatographing the reduced, carboxymethylated whole protein upon columns of S-P Sephadex C-50. This method is suitable, as a preliminary step, in the further study of either normal or abnormal fibrinogen.     

The use of fibrinogen uptake test in screening for deep vein thrombosis in patients with hip fracture

255 hip fracture patients were studied by 125I-fibrinogen uptake test and bilateral phlebography. We found the sensitivity of fibrinogen scanning to be 44% for the non-operated limb and 50% for the calves. The predictive value of a negative result was found to be 92% and 93% respectively. We conclude that the use of fibrinogen uptake test as single diagnosticum is not valid and can only be recommended in combination with phlebography when studying patient where the frequency of DVT is expected to be low.