Haemostatic profile of healthy premature small for gestational age neonates

Background

The pathogenetic profile of premature Small for Gestational Age (SGA) neonates is strongly related to their haemostatic equilibrium, which is inadequately understood.

Objective

To evaluate coagulation and fibrinolysis in premature SGA neonates before intervening with Vitamin K administration.

Study design

We performed a comparison of coagulation, natural inhibitors and fibrinolysis between SGA and Appropriate for Gestational Age (AGA) infants born prematurely [gestational age (G.A.) < 37 weeks]. Study population consisted of 139 preterm newborns, 68 of whom were SGA (25 males and 43 females), while 71 were AGA (37 males and 34 females) that consisted the control group. Blood samples were obtained within 30 minutes following birth and before the administration of vitamin K. Investigation included: PT, INR, APTT, fibrinogen, coagulation factors II, V, VII, VIII, IX, X, XI, XII, vWillebrand factor, protein C and free protein S, antithrombin (AT), APCR, tPA and PAI-1. The independent t-test and the Mann-Whitney U test were used to compare the differences between the values of haemostatic parameters.

Results

Premature SGA infants presented significantly lower levels of fibrinogen (p < 0.029) and higher levels of VIIIc factor, APCR, tPA and PAI-1 (p < 0.041, 0.017, 0.021 and 0.019 respectively). The two groups had similar demographic characteristics (except from birth weight), without significant differences in the values of other haemostatic parameters.

Conclusions

Despite the statistically significant differentiation in the levels of fibrinogen, VIIIc factor, APCR, tPA and PAI-1, the rest of haemostatic parameters have similar values between SGA and AGA preterms.     

Comparison and evaluation of a Point-of-care device (CoaguChek XS) to Owren-type prothrombin time assay for monitoring of oral anticoagulant therapy with warfarin

Background

The standardized test used for evaluating the effect of warfarin is the prothrombin time (PT) which is measured and expressed in international normalized ratio (INR). Regular control of treatment intensity is required since inappropriate dosage increases the risk for complications. Portable point-of-care analytical instruments for measurement of capillary whole blood PT have been available for the last decades. The purpose of this study was to compare and evaluate INR values obtained by the point-of-care device CoaguChek XS, to Owren PT in a hospital setting.

Materials and Methods

In 397 warfarin-treated patients, capillary whole blood was analyzed with the CoaguChek XS and the results were compared to analysis of venous plasma samples with the Owren PT assay. To study reproducibility and rule out preanalytical errors, a subgroup of 152 patients had two capillary blood samples analyzed with the CoaguChek XS.

Results

In 397 patients, with a median age(±2SD) of 69.0(50-88) years, there was a positive correlation between results from the CoaguChek XS and the Owren-type PT assay (r = 0.94;p < 0.001) and concordance of 88.2%. The mean INR difference (S.D) was 0.02 (0.22). Comparison of the 152 double samples analyzed with the CoaguChek XS, produced a positive correlation of 0.99; p < 0.001.

Conclusions

The CoaguChek XS presents reproducible, highly comparable results with Owren PT at therapeutic levels of INR. The CoaguChek XS seems to produce better results than the earlier CoaguChek S, probably due to a new method of PT measurement where levels of fibrinogen and haematocrit do not affect the outcome.     

Kynurenines and oxidative status are independently associated with thrombomodulin and von Willebrand factor levels in patients with end-stage renal disease

Introduction

Increased oxidative stress (SOX) is one of the most potent inductors of endothelial dysfunction in end-stage renal disease (ESRD) patients. Kynurenines are the metabolites of tryptophan (TRP) degradation in mammals. However, the role of kynurenines in the function of the endothelium is still not recognized.

Materials and methods

We determined the plasma concentrations of TRP, kynurenine (KYN), 3-hydroxykynurenine (3-HKYN), quinolinic acid (QA); markers of SOX: Cu/Zn superoxide dismutase (Cu/Zn SOD), malondialdehyde (MDA); and endothelial dysfunction markers: thrombomodulin (TM) and von Willebrand factor (vWF) levels in 148 ESRD patients and healthy controls.

Results

TM, vWF, KYN, 3-HKYN and QA levels were significantly elevated in ESRD patients compared to controls. TRP concentrations in uremics were significantly lower than in healthy people. Both dialyzed groups showed a significant increase Cu/Zn SOD and MDA levels compared to controls. TM and vWF were positively associated with kynurenine pathway metabolites: KYN, 3-HKYN, QA (all p < 0.001), and with SOX markers: Cu/Zn SOD (both p < 0.0001) and MDA levels (p < 0.05, and p < 0.0001; respectively) in the whole ESRD group. The positive relationship were between Cu/Zn SOD and KYN (p < 0.010), 3-HKYN and QA levels (both p < 0.0001), whereas MDA was correlated with 3-HKYN and QA concentrations (both p < 0.05). Multiple stepwise regression analysis showed that KYN metabolites and oxidative status were the independent variables significantly associated with increased both TM and vWF levels in uremic patients.

Conclusions

Our study demonstrated that kynurenine metabolites and increased oxidative status are independently and significantly associated with endothelial dysfunction in ESRD patients.     

Prognostic value of pre-surgical plasma PAI-1 (plasminogen activator inhibitor-1) levels in breast cancer

Introduction

Plasminogen activator inhibitor (PAI-1) may have an independent prognostic value in breast cancer (BC). PAI-1 4G/5G polymorphism may have significance for antigen expression. Thus, we analyzed the possible associations between PAI-1 4G/5G polymorphism, plasma PAI-1 levels, and clinicopathological features of breast cancer (BC) patients.

Patients and Methods

PAI-1 4G/5G polymorphism (both on germinal and tumor DNA) and plasma PAI-1 levels were investigated in 99 BC patients and 50 unrelated healthy women similar for age and menopausal status.

Results

No association was found between allele frequencies and clinicopathological features of BC or plasma antigen levels. Plasma PAI-1 levels were higher in BC compared to controls (p = 0.002), particularly in patients with large tumors (p < 0.001). 5-year follow-up was achieved in 79 patients: 30% had relapsing disease, 63% with positive compared to 37% with negative PAI-1 levels (p < 0.05). 5-year relapse-free survival rate of positive PAI-1 was 46% vs., 77% of negative patients (p = 0.02).

Conclusions

We may conclude that plasma PAI-1 levels in BC patients could represent a useful prognostic variable for relapse, although PAI-1 polymorphism might not represent a genetic susceptibility factor.     

Smoking promotes clopidogrel-mediated platelet inhibition in patients receiving dual antiplatelet therapy

Background

High on-treatment residual platelet reactivity is associated with an increased risk of adverse events after coronary stenting. Recent data suggest that cigarette smoking might enhance clopidogrel-mediated platelet inhibition. We therefore sought to investigate the influence of cigarette smoking on clopidogrel- and aspirin-mediated platelet inhibition after percutaneous intervention with stent implantation.

Patients and methods

Platelet aggregation was assessed by the VerifyNow P2Y12 and aspirin assays in 102 patients on dual antiplatelet therapy 24 hours after peripheral, coronary or carotid artery stenting. Among these, there were 33 nonsmokers, 29 former smokers and 40 current smokers. Patients in the fourth quartile of the VerifyNow assays were considered as patients with high on-treatment platelet reactivity.

Results

Current smokers had significantly lower P2Y12 Reaction Units compared with nonsmokers (p = 0.028). Former smokers also had lower adenosine diphosphate (ADP)-inducible platelet aggregation than nonsmokers, but the difference was not significant (p = 0.52). A high on-treatment residual ADP-inducible platelet aggregation was more common among nonsmokers than among current smokers (14 vs 5; p = 0.004). In a multivariate regression analysis smoking was an independent influencing variable for post-treatment ADP-inducible platelet reactivity (p = 0.026). Aspirin-mediated platelet inhibition showed no significant differences between nonsmokers and former smokers or current smokers (p > 0.3).

Conclusion

By in vitro testing, cigarette smoking is associated with enhanced clopidogrel- but not aspirin-mediated platelet inhibition. The clinical implications have to be evaluated in large prospective trials.     

Platelet inhibition assessed with VerifyNow, flow cytometry and PlateletMapping in patients undergoing heart surgery

Introduction

A substantial number of patients with coronary artery disease undergo cardiac surgery within five days of discontinuing anti-platelet treatment with aspirin and clopidogrel. The aims of this study were to describe the degree of platelet inhibition in patients with dual anti-platelet treatment scheduled for coronary artery bypass graft (CABG) surgery and to investigate whether the measured platelet inhibition correlated to intra- and postoperative risk for bleeding and transfusion requirements.

Material and Methods

Sixty patients were included. Platelet inhibition was analysed with flow cytometry including phosphorylation status of the vasodilator-stimulated phosphoprotein (VASP-assay) and two bed-side analyzers, VerifyNow-System and PlateletMapping, a modified thrombelastograph. All 60 patients were analysed with VerifyNow and PlateletMapping, and 48 were analysed with flow cytometry and VASP-assay.

Results

There was a correlation between the ADP-receptor inhibition as measured by VASP-assay and VerifyNowP2Y₁₂ (r = - 0.29, p < 0.05), and between VASP-assay and the expression of P-selectin (r = 0.29, p < 0.05) as measured by flow cytometry when platelets were stimulated with 5 µM ADP. VerifyNowP2Y₁₂ was the only measurement of platelet inhibition correlated to total blood loss (Spearman r = 0.29, p = 0.03) and red blood cell transfusion (Spearman r = 0.43, p < 0.01) requirements, although this might be confounded by aprotinin treatment.

Conclusion

We found a modest agreement between the methods for preoperative platelet inhibition, though not for PlateletMapping-MA_ADP. There was a correlation between preoperative platelet inhibition measured by VerifyNowP2Y₁₂ and surgical blood loss or transfusion requirements. However, for the individual patient, preoperative use of VerifyNowP2Y₁₂ as an instrument to decide bleeding and transfusion risk does not seem helpful.     

Shear-induced global thrombosis test of native blood: Pivotal role of ADP allows monitoring of P2Y12 antagonist therapy

Background

It is claimed that in shear-induced platelet function tests, shear-stress is the sole agonist causing platelet activation and resultant thrombosis. However, the fact that red blood cells (RBC) are essential to achieve platelet aggregation in these tests supports recent evidence that ADP makes an important contribution to shear-induced platelet reaction.

Aim

To establish the role of ADP in shear-induced thrombosis, and investigate whether a shear-induced thrombosis test can assess ADP-receptor (P2Y12) antagonist medication.

Methods

Blood from healthy volunteers was tested using the Global Thrombosis Test (GTT), before and after clopidogrel. To investigate the importance of contact of blood with plastic, the reactive part of the tube was primed with saline. We also investigated the effect of priming the tube with water, to cause localised haemolysis and ADP release.

Results

Saline-priming prolonged occlusion times (OT) by 25% (p < 0.01) confirming ADP release from platelets and RBC as a result of contact. Water-priming shortened OT, accelerating the thrombotic reaction (accelerated GTT; aGTT) (OT 379 vs. 177s, p < 0.01). Clopidogrel increased OT (379 vs. 477s, p < 0.01), preventing the shortening of aGTT-OT (177 vs. 362s, pre- and post-clopidogrel; p < 0.01).

Conclusion

In addition to thrombin formation, ADP released from platelets and RBC in native blood subjected to high shear-stress makes an important contribution to the resultant thrombotic occlusion. The described aGTT sensitively detected the effect of clopidogrel and thus seems suitable for monitoring and individualizing ADP-receptor antagonist therapy. Parallel measurement of GTT and aGTT would allow assessment of both global thrombotic status and response to P2Y12 antagonist therapy.     

Evaluation of the platelet count drop method for assessment of platelet function in comparison with “gold standard” light transmission aggregometry

Introduction

Hyporesponsiveness to antiplatelet agents has been linked to an increased risk of major adverse cardiovascular events. However, light transmission aggregometry (LTA), the gold standard methodology for assessing platelet function, requires expertise and is labour-intensive, which render its use in clinical settings impractical. We assessed whether platelet count drop (PCD), a technique widely available in any haematology laboratory, could replace LTA in testing for inhibition of platelet aggregation induced by antiplatelet agents.

Materials and methods

One hundred and sixty-one coronary artery disease patients taking aspirin alone and 91 patients taking a combination of aspirin and clopidogrel were enrolled. Platelet aggregation was measured by LTA and PCD stimulated with 1.6 mM of arachidonic acid (AA) for aspirin and 5 and 20 μM of adenosine diphosphate (ADP) for clopidogrel.

Results

Correlation between AA-induced LTA and PCD was inexistent (r = - 0.043, p = 0.587), while correlation between ADP-induced LTA and PCD was low (r = 0.374, p < 0.0001 for ADP 5 μM and r = 0.402, p < 0001 for ADP 20 μM). PCD, whether stimulated with AA or ADP, overestimated platelet aggregation as assessed by LTA, by 13-18%. The wide 95% limits of agreement suggest that the assays can disagree significantly in individual patients.

Conclusions

Although the PCD method is widely available in non-specialized laboratories, our results demonstrate that there is poor correlation with the current gold standard, i.e. LTA. Thus, PCD should not be used in replacement of LTA to assess antiplatelet responsiveness.     

Impact of P2Y12 Inhibitory Effects Induced by Clopidogrel on Platelet Procoagulant Activity in Type 2 Diabetes Mellitus Patients

Introduction

Type 2 diabetes mellitus (T2DM) patients have a variable response profile to the P2Y₁₂ receptor antagonist clopidogrel. P2Y₁₂ receptor signalling promotes platelet procoagulant activity. The aim of this study was to determine if T2DM patients with suboptimal clopidogrel response have greater platelet procoagulant activity compared with optimal responders and evaluate if this can be modulated by enhancing P2Y₁₂ receptor inhibition.

Materials and Methods

A total of 50 T2DM patients in a steady state phase of clopidogrel therapy were studied. Suboptimal responders were randomly assigned to standard (75 mg) or high (150 mg) clopidogrel maintenance therapy for one-month. Afterwards, all patients resumed standard therapy. Platelet procoagulant activity assessed by thrombin-induced platelet-fibrin clot formation using thrombelastography (TEG) was determined at baseline, one-month post-randomization, and one-month after resuming standard therapy.

Results

In the overall study population, the reaction time (R), a measure of time to initial thrombin induced platelet-fibrin clot formation, and the time to maximum rate of thrombin generation (TMRTG) values were 6.3 ± 1.7 and 7.6 ± 1.9 minutes, respectively. Suboptimal clopidogrel responders (n = 30) had acceleration of R (p = 0.002) and TMRTG (p = 0.002) compared to optimal responders (n = 20). Suboptimal clopidogrel responders treated with a 150 mg dose showed prolongation of R (p = 0.0001) and TMRTG (p < 0.0001), which returned to baseline values after resuming standard dosage. No differences were observed among patients randomized to 75 mg.

Conclusions

T2DM patients with suboptimal clopidogrel response have enhanced platelet procoagulant activity compared to patients with optimal response, which can be down-regulated by more potent platelet P2Y₁₂ inhibition using high clopidogrel maintenance dosing.     

Thrombin-activatable fibrinolysis inhibitor genetic polymorphisms as markers of the type of acute coronary syndrome

Introduction

In patients with coronary disease at risk of acute coronary events it is unclear which biological factors could predict the type of acute coronary syndrome clinical presentation. The aim of the study was to investigate the role of genetic polymorphisms in key proteins in fibrinolysis in the type of acute coronary syndrome.

Materials and methods

248 patients with acute coronary syndrome (unstable angina or myocardial infarction) (77% male, mean age 60.75 SD 13.30 years) were prospectively recruited. PAI-1 (type-1 plasminogen activator inhibitor) 4G/5G and TAFI (thrombin-activatable fibrinolysis inhibitor) Ala147Thr, C+1542G, and Thr325Ile polymorphisms were determined by PCR.

Results

147 (59.3%) patients presented with ST-segment elevation acute coronary syndrome (all Q-wave myocardial infarction), and 101 (40.7%) with non-ST-elevation acute coronary syndrome (52 non-Q wave myocardial infarction, and 49 unstable angina). Homozygous TAFI + 1542G and TAFI 325Ile genotypes were less prevalent in patients with ST elevation acute coronary syndrome (p < 0.001, OR: 0.22, 95% CI 0.10-0.50 and p < 0.001, OR: 0.25, 95% CI 0.11-0.55, respectively). There were no differences in TAFI Ala147Thr or PAI genotype distribution between ST elevation and non-ST elevation acute coronary syndrome. In the multivariate analysis including clinical variables, the best model for ST elevation acute coronary syndrome included TAFI + 1542GG (p < 0.001, OR: 0.17, 95% CI 0.07-0.30), age (in years, p < 0.005, OR: 0.97, 95% CI 0.94-0.98) and dyslipidemia (p < 0.005, OR: 2.33, 95% CI 1.42-3.80).

Conclusion

TAFI polymorphism C+1542G and Thr325/Ile are related to the type of acute coronary syndrome. Patients with coronary disease would benefit from individualized cardiovascular prophylaxis based on genetic risk.     

Association of the -757T>C polymorphism in the CRP gene with circulating C-reactive protein levels and carotid atherosclerosis

Introduction

C-reactive protein (CRP) is an inflammatory protein that may play a role in the pathogenesis of atherosclerosis. CRP gene single nucleotide polymorphisms (SNPs) have been shown to be associated with CRP concentration; however, their independent effect on atherosclerosis has not been yet established. We aimed to determine whether the 5′-flanking -757T>C CRP gene polymorphism is associated with CRP concentration and carotid atherosclerosis.

Methods

We genotyped the -757T>C CRP gene SNP and determined the concentration of serum CRP, the intima-media thickness (IMT) of the common carotid artery and the existence of plaque/s in 612 apparently healthy men and women aged 66 ± 10 years.

Results

Carriers of the CRP -757C allele presented with higher IMT and higher CRP concentrations (p = 0.002, p = 0.042, respectively). After adjustment for vascular risk factors, linear regression analysis showed an independent effect of CRP -757C allele on carotid IMT, beyond serum CRP concentrations. This SNP was also associated with carotid plaque occurrence (O.R. 1.74, 95% CI 1.1-2.77, p = 0.002).

Conclusions

The present study provides evidence that a genetic variant of CRP gene is associated with carotid atherosclerosis, independently of traditional vascular risk factors. Further large-scale genomic studies are required, which may identify the genetic vulnerable subjects to develop atherosclerosis.     

Differential alteration of automatic semantic processing in treated patients affected by bipolar mania and schizophrenia: an N400 study

Background

Various formal thought disorders are presented as symptoms by manic patients including pressure of speech, flight of ideas, and more complex speech with strong emotional components. N400 is the event-related potential, in which amplitude is suggested to be a general index of efforts to retrieve stored semantic context, which depends on the stored representation itself and the retrieval cue stimuli. The present study examines N400 components induced by a word-matching task in manic patients, and compare these responses to those induced by the task in schizophrenia and healthy controls.

Methods

Twenty manic patients, twenty schizophrenic patients, and twenty healthy controls performed the word-matching task, in which they were presented with 120 (60 congruent and 60 incongruent) word pairs, they were instructed to discriminate whether each word pair was congruent or incongruent. During the task, we recorded the electroencephalogram.

Results

Reaction time analysis revealed a main effect for priming, in which reaction times were longer in response to incongruent words than to congruent words in all three participant groups (F = 43.1, p < 0.001) with no group effects (F = 2.3, p = 0.11). N400 analysis showed the main effect for priming (F = 30.2, p < 0.001), for group (F = 5.0, p = 0.01), and the interaction of priming × group (F = 4.6, p = 0.02). Post-hoc analysis of this interaction revealed larger N400 amplitudes to congruent words in manic patients (F = 4.0, p = 0.02) and smaller N400 to incongruent words in schizophrenic patients than in other groups (F = 6.1, p = 0.004). No correlations were found between N400 and symptom severity within patient groups.

Conclusions

These findings suggest that priming effects of contextually related word pairs are decreased in patients with bipolar mania, whereas priming N400 responses of contextually unrelated word pairs are increased in schizophrenia. This may be the neurophysiological evidence of abnormal automatic semantic processing in patients with bipolar mania, and it also reflects a qualitative difference in thought and speech disorders between bipolar manic and schizophrenia.     

Risk factors for unfavorable clinical outcome in patients with documented heparin-induced thrombocytopenia

Background

Prognostic factors for unfavorable clinical outcome in patients with heparin-induced thrombocytopenia (HIT) are largely unknown.

Design and methods

In this multicenter, retrospective, case-control study, all HIT patients were treated with danaparoid. Study cases were HIT patients with an unfavorable clinical outcome. Controls were HIT patients who were not study cases. Unfavorable clinical outcome was defined as the occurrence of at least one of the following clinical events: death within 60 days after HIT start date, or venous or arterial thromboembolism, amputation, major bleeding, or disseminated intra-vascular coagulation between 48 hours and 60 days after HIT start date.

Results

Compared with controls (n = 65), thrombotic episodes within 48 hours of HIT start date were more frequent (59.2% versus 32.3%; p = 0.004), the median time between HIT start date and initiation of danaparoid infusion was longer (3.0 versus 1.0 days; p = 0.001), and this treatment was more frequently underdosed (43.8% versus 18.8%; p = 0.004) in study cases (n = 49). Upon multivariate analysis, all these three parameters were significant predictive factors for unfavorable clinical outcome. The adjusted odds ratios [95% confidence interval] were 6.6 [2.5-17.3] for time between HIT start date and danaparoid initiation over 48 hours, 4.3 [1.5-12.0] for danaparoid underdosing, and 3.2 [1.3-8.0] for presence of a thromboembolic episode at HIT start date.

Conclusions

This study supports the recommendations concerning the management of HIT patients, namely discontinuation of all heparin administration once the diagnosis is suspected and prompt initiation of an alternative anticoagulant drug with a strict adherence to doses specifically recommended for these patients.     

Carbon Monoxide Releasing Molecule-2 Enhances Coagulation and Diminishes Fibrinolytic Vulnerability in Subjects Exposed to Warfarin

Introduction

It has been recently demonstrated that a carbon monoxide releasing molecule (tricarbonyldichlororuthenium (II) dimer; CORM-2) enhances coagulation and attenuates vulnerability to fibrinolysis in normal and hemophiliac human plasma. We tested the hypothesis that plasma obtained from warfarin-treated subjects would demonstrate improved coagulation and decreased fibrinolytic vulnerability following exposure to CORM-2.

Materials and Methods

Anonymous donor plasma samples with international normalized ratios (INR) values ranging from 1.5-5.4 were exposed to 0 or 100 µM CORM-2 and activated with tissue factor (12 samples). Additional samples within the same INR range were exposed to 0 or 100 µM CORM-2 and 0 or 100 U/ml tissue-type plasminogen activator (tPA) to assess fibrinolytic vulnerability (8 samples). Thrombelastographic data were collected until either clot strength stabilized or clot lysis occurred as appropriate.

Results and Conclusions

In the absence of tPA, all but one sample (INR=1.5) demonstrated a marked increase in the velocity of clot formation (40-577%) and strength (42-180%) following CORM-2 exposure. Of interest, in the presence of tPA, all samples (including the previously unresponsive sample) were noted to have an increase in the velocity of clot formation and strength, coupled with a prolonged onset to maximal rate of clot lysis (60-242%) and increased clot lysis time (74-149%). As with normal and hemophilic plasma, both enhancement of coagulation and attenuation of fibrinolysis occur following CORM-2 exposure in plasma from warfarin-treated subjects. Future investigation must determine if carbon monoxide releasing molecules could be used therapeutically to control bleeding in warfarin-treated patients.     

Parameters of the thrombogram are associated with serum 25-hydroxyvitamin D levels at baseline, but not affected during supplementation with vitamin D

Introduction

In vitro studies indicate an anticoagulant effect of 1,25-dihydroxyvitamin D, and sun exposure may lower the risk of thrombotic events. Accordingly, an effect on haemostatic parameters could be expected after supplementation with vitamin D.

Materials and Methods

158 obese or overweight subjects were included in a one year intervention study with supplementation with 40.000 IU vitamin D₃ per week or placebo. All subjects were given 500 mg calcium daily. Plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator antigen (tPA Ag), and tissue factor-induced thrombin generation over time in plasma assessed by the calibrated automated thrombogram (CAT) method as a parameter of over all thrombotic activity, were measured before and at the end of the study.

Results

Mean baseline serum 25(OH)D level was 61.8 nmol/L and increased in the vitamin D group to 145.6 nmol/L at the end of the study. At baseline there was a significant decrease in the CAT variables lag time and time to peak of the thrombogram across increasing serum 25(OH)D quartiles, whereas no significant associations between serum 25(OH)D and PAI-1 or tPA Ag were found. After one year, no significant differences were found between the vitamin D and placebo groups regarding change in any of the haemostatic parameters.

Conclusions

The association between lag time and time to peak in the CAT assay and serum 25(OH)D levels could indicate a pro-thrombotic state in subjects with high serum 25(OH)D levels, whereas the lack of effect of high dose vitamin D supplementation questions the causality of this relation.     

Haemostatic markers in patients with abdominal aortic aneurysm and the impact of aneurysm size

Introduction

Abdominal aortic aneurysm is a common condition with high mortality when rupturing. However, the condition is also associated with nonaneurysmal cardiovascular mortality. A possible contributing mechanism for the thrombosis related cardiovascular mortality is an imbalance between the activation of the coagulation system and the fibrinolytic system. The aim of the present study was to investigate haemostatic markers in patients with nonruptured abdominal aortic aneurysm with special regard to the influence of aneurysm size and smoking habits.

Methods

Seventy-eight patients with infrarenal aortic aneurysm and forty-one controls without aneurysm matched by age, gender and smoking habits were studied. Thrombin-antithrombin (TAT), prothrombin fragment 1 + 2 (F 1 + 2) - markers of thrombin generation, and von Willebrand factor antigen (vWFag) - considered as a reliable marker of endothelial dysfunction - were measured. Plasma levels of tissue plasminogen activator antigen (tPAag), and plasminogen activator inhibitor type 1 (PAI-1) were measured as markers of fibrinolytic activity. D-dimer, a marker of fibrin turnover, was also measured.

Results

There were significantly higher levels of TAT and D-dimer in patients with abdominal aortic aneurysm. The highest level of TAT and D-dimer were detected in patients with large compared to small AAA.

Conclusions

The present data indicate a state of activated coagulation in patients with abdominal aortic aneurysm which is dependent by aneurysm size. The activated coagulation in AAA patients could contribute to an increased cardiovascular risk in patients also with small AAA. The possible impact of secondary prevention apart from smoking cessation has to be further evaluated and is maybe as important as finding patients at risk of rupture.     

Haemostatic system, biochemical profiles, kynurenines and the prevalence of cardiovascular disease in peritoneally dialyzed patients

Introduction

The haemostatic and biochemical abnormalities participate in the progression of cardiovascular disease (CVD) in peritoneally dialysed (PD) patients. Recently, the role of kynurenine (KYN) pathway of tryptophan (TRP) degradation in the development of CVD has been postulated.

Materials and methods

The present study was undertaken to investigate haemostatic parameters, biochemical profiles and kynurenines in PD patients both with and without CVD compared to age- and sex-matched healthy controls.

Results

The multiple biochemical abnormalities were present in PD patients, particularly in those with CVD. Tissue factor (TF), its inhibitor (TFPI), prothrombin fragment 1 + 2 (F_1 + 2)_, urokinase-type plasminogen activator (uPA), its soluble receptor (suPAR), plasmin/antiplasmin (PAP) complexes, KYN, kynurenic (KYNA) and quinolinic (QA) acids levels were significantly higher, whereas TRP was significantly lower in the PD patients than in the controls. Tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) were higher in the patients with CVD than in the patients without CVD and controls. PD patients with CVD had higher F_1 + 2, and they had lower suPAR and KYNA levels compared with PD patients without CVD. KYNA was positively associated with TFPI, whereas its was inversely associated with F_1 + 2 both in the whole PD group and in CVD patients. Logistic regression analysis showed that low KYNA, high glucose, low HDL-cholesterol levels and the duration of dialysis treatment were independently associated with the presence of CVD in PD patients.

Conclusions

The present study suggests a relationship between kynurenine pathway of tryptophan degradation, haemostatic and biochemical disturbances and CVD prevalence in peritoneally dialyzed patients.     

PDE4 regulates tissue plasminogen activator expression of human brain microvascular endothelial cells

Introduction

Factors regulating brain tissue plasminogen activator (tPA) are pertinent for stroke. Recent observations have suggested a role for the phosphodiesterase-4 (PDE4) pathway in stroke pathogenesis, via an uncertain mechanism. We studied PDE4 regulation of tPA expression by human brain microvascular endothelial cells in a variety of conditions, including an in vitro model of ischemia.

Materials and Methods

We analyzed tPA antigen and mRNA of human brain microvascular endothelial cells (HBECs) during normoxia and oxygen-glucose deprivation (OGD) following inhibition of PDE4 and PDE4D, using HBEC monocultures and co-cultures with astrocytes and pericytes, and analyzed relevant signal transduction pathways.

Results

PDE4 inhibitor rolipram enhanced OGD effects on endothelial tPA release in endothelial monocultures and co-cultures with astrocytes; there was a 54 ± 10% (p < 0.001) reduction of tPA release in astrocyte-endothelial co-cultures under OGD. PDE4D siRNA reduced endothelial tPA mRNA to 40-55% of control (p < 0.05). Use of Epac inducer mimicked, while use of Epac siRNA inhibited, these effects.

Conclusions

Inhibition of PDE4 and PDE4D reduced expression of tPA by HBEC via Epac pathway.     

Effects of carvedilol or metoprolol on PAI-1, tPA-mass concentration or Von Willebrand factor in chronic heart failure - a COMET substudy

Introduction

In COMET (Carvedilol or Metoprolol European Trial), carvedilol reduced mortality compared with metoprolol in patients with chronic heart failure. We hypothesized that carvedilol might have greater effects on endothelial derived haemostatic factors than metoprolol. We aimed to study the effects of carvedilol or metoprolol on tissue plasminogen activator (tPA), its inhibitor PAI-1 and Von Willebrand factor (VWF) in patients with heart failure.

Material and Methods

We recruited 260 patients (134 on carvedilol, 126 on metoprolol), mean age 66 years and 84% of them men. Plasma mass concentrations of tPA and PAI-1and percent of VWF were measured at baseline and after one and two years of treatment.

Results

Plasma tPA, PAI-1 and VWF were similar between treatment groups at baseline and no significant differences between groups emerged after one or two years of treatment. In paired analyses in patients assigned to carvedilol, median PAI-1 level decreased from 37.2 to 32.1 µg/l at two years (p = 0.034) and of VWF decreased from baseline to one year (240 vs. 218%, p = 0.023) in patients assigned to carvedilol but were not reduced at any time in patients assigned to metoprolol. Plasma tPA increased over time in both treatment groups (p = 0.013 and 0.027 respectively).

Conclusion

We found no significant difference in the effects of carvedilol or metoprolol on tPA, PAI-1 and VWF. Comparison over time within treatment groups suggested that PAI-1 and VWF might have declined on carvedilol but not on metoprolol. Our hypothesis is not proved but this may reflect an inadequate sample size rather than lack of an effect.     

Release of necrosis markers and cardiovascular magnetic resonance-derived microvascular perfusion in reperfused ST-elevation myocardial infarction

Introduction

The association of the temporal evolution of cardiac necrosis marker release with cardiovascular magnetic resonance-derived microvascular perfusion after ST-elevation myocardial infarction is unknown.

Methods

We analyzed 163 patients with a first ST-elevation myocardial infarction and a patent infarct-related artery treated with thrombolysis (67%) or primary angioplasty (33%). Using first-pass perfusion CMR, abnormal perfusion was defined as a lack of contrast arrival into the infarct area in > 1 segment. Troponin I, creatine kinase MB and myoglobin were measured upon arrival and at 6, 12, 24, 48 and 96 hours after reperfusion.

Results

Abnormal perfusion was detected in 75 patients (46%) and was associated with a larger release of all 3 necrosis markers after reperfusion and higher peak values. This association was observed in the whole group and separately in patients treated with thrombolysis and primary angioplasty. Out of the 3 markers, troponin levels at 6 hours after reperfusion yielded the largest area under the receiver operating characteristic curve for prediction of abnormal perfusion (troponin: 0.69, creatine kinase MB: 0.65 and myoglobin: 0.58). In a comprehensive multivariate analysis, adjusted for clinical, angiographic, cardiovascular magnetic resonance parameters and all necrosis markers, high troponin levels at 6 hours after reperfusion (>median) independently predicted abnormal microvascular perfusion (OR 2.6 95%CI [1.2 - 5.5], p = .012).

Conclusions

In ST-elevation myocardial infarction, a larger release of cardiac necrosis markers soon after reperfusion therapy relates to abnormal perfusion. Troponin appears as the most reliable necrosis marker for an early detection of cardiovascular magnetic resonance-derived abnormal microvascular reperfusion.