Carotid Stent Restenosis and Thrombosis in Rabbits: The Effect of Antiplatelet Agents.

BACKGROUND: The purpose of the study was the comparative assessment of ticagrelor and clopidogrel effects on carotid post-balloon injury (PBI) and on post carotid artery stenting (CAS) rate of in-stent restenosis (ISR) and in-stent thrombosis in atherosclerotic rabbits. METHODS: Forty-eight New Zealand white rabbits on high-fat diet were randomized into 4 groups: A1: PBI and clopidogrel (30 mg/kg/d), A2: PBI and ticagrelor (21 mg/kg twice daily), B1: PBI, CAS, and clopidogrel (30 mg/kg/d), B2: PBI, CAS, and ticagrelor (21 mg/kg twice daily). All rabbits received orally aspirin (10 mg/kg/d) and interventions were performed in their right carotid arteries (RCAs). Optical coherence tomography (OCT) and carotid angiography were performed at end point, while platelet aggregation and lipid profile were measured. After euthanasia both carotids were obtained for histological examination. RESULTS: In B1 group, 3 rabbits presented thrombotic total occlusion of the stents, while none such episode was observed in B2 group. The neointimal areas in RCAs, calculated by OCT, did not differ between A1 and A2 groups, and between B1 and B2 groups (P > .05). From the histological findings, the intima/(media + intima) percentage (%) in RCAs of balloon-injured rabbits did not present any difference between groups (P = .812). Similarly, the immunohistochemically determined accumulation of endothelial cells and macrophages on vascular walls was equivalent between groups (P > .05). CONCLUSION: Following carotid balloon injury and stenting, clopidogrel and ticagrelor did not show any differential effects on the extent of neointimal formation and ISR in atherosclerotic rabbits receiving aspirin. Three thrombotic stent occlusions were noted in the clopidogrel treatment group, but this finding was not statistically significant.

Protein Z (PZ) and plasminogen activator inhibitor-1 (PAI-1) plasma levels in patients with previously untreated Hodgkin lymphoma (HL).

PURPOSE: The role of Protein Z (PZ) in conditions, such as thrombosis, inflammation or cancer, is under investigation. Plasminogen Activator Inhibitor-1 (PAI-1) is an acute phase reactant that promotes thrombosis and tumorigenesis. Subject of this work was to study PZ and PAI-1 in patients with Hodgkin Lymphoma (HL), a malignancy with inflammatory background and relatively low incidence of thrombosis. METHODS: Newly diagnosed patients were enrolled in the study. Healthy individuals were used as controls. RESULTS: PZ levels were higher in patients compared to controls (not significantly), while PAI-1 levels were significantly higher in patients. Both PZ and PAI-1 concentrations did not correlate with most of patients' characteristics. Lower PZ levels at diagnosis were associated with presence of B symptoms and positive final positron emission tomography (PET) and higher baseline PAI-1 levels with positive final PET, too. PZ had a declining trend, but PAI-1 increased initially and decreased thereafter, during the treatment period. CONCLUSIONS: Conclusively, PAI-1, but not PZ, seems to be an acute phase protein in HL. Lower PZ and higher PAI-1 levels at diagnosis may be indicative of aggressive disease. These results need further verification.

Endothelial Protein C Receptor Gene Variants and Risk of Thrombosis.

Endothelial protein C receptor (EPCR) is a candidate mediator in the pathogenesis of thrombosis, as several data in the literature indicate that polymorphisms such as EPCR 4678G/C and 4600A/G are associated with either protective effect or increased risk of thrombosis, respectively. We investigated the prevalence of these polymorphisms in patients with thrombotic disorders as well as their impact on the risk of thrombosis, the age of first thrombotic episode, and recurrence. The prevalence of the rare EPCR alleles 4600G and 4678C was comparable in patients and controls. However, in a subset analysis, we observed that 4600G allele was more prevalent among patients who developed thrombosis at younger age (<35 years). Moreover, the prevalence of 4678C allele was significantly lower in younger patients compared to older patients. Neither polymorphism seemed to have an impact on recurrence regardless of age. Soluble EPCR levels were elevated in 4600AG patients compared to controls while 4678CC patients presented with lower levels of soluble form of EPCR compared to carriers of at least 1 4678G allele. Our data suggest that either the lack of the protective EPCR 4678C allele or the presence of EPCR 4600G allele may be associated with earlier development of thrombosis.

Retinal vein occlusion: genetic predisposition and systemic risk factors.

The role of systemic risk factors (age, smoking, diabetes, arterial hypertension) in the development of retinal vein occlusion (RVO) is well established. However, the association of RVO with genetic predisposition to thrombosis remains poorly understood. The aim of the study was to assess any possible additional effect of genetic predisposition to the already well known 'classical' risk factors of RVO in a cohort of elderly Greek patients. Fifty-one elderly patients with RVO and 51 healthy individuals matched for age and sex were evaluated for systemic risk factors (smoking, diabetes, dyslipidemia, arterial hypertension) and coagulation defects (lupus anticoagulant, natural inhibitors of coagulation). Additionally, genotyping was performed for mutations/polymorphisms involved in haemostasis such as: FV G1691A, FV G4070A, FIIG 20210A, MTHFR C677T and A1298C, PAI-1-675 4G/5G, F XIII exon 2G/T, EPCR A4600G and G4678C. We identified systemic risk factors in the majority of the patients Hypertension (P=0.001), dyslipidemia (P=0.029) and diabetes (P=0.01) are associated with RVO in the majority of the patients. The prevalence of prothrombotic risk factors was not significantly different in the patients with RVO compared to controls. Apart from systemic risk factors, genetic predisposition to thrombosis does not seem to have an important association with RVO in this group of elderly patients.

Red blood cell transfusion affects microdialysis-assessed interstitial lactate/pyruvate ratio in critically ill patients with late sepsis.

PURPOSE: The aim of this study was to explore the effect of red blood cell (RBC) transfusion on microdialysis-assessed interstitial fluid metabolic parameters in septic patients. METHODS: We conducted a retrospective study of 37 patients with severe sepsis/septic shock requiring transfusion of one to two RBC units. Interstitial fluid metabolic alterations were monitored by a microdialysis catheter inserted in the subcutaneous adipose tissue. Samples were collected before (T0) and after transfusion at two time-points: T1a and T1b; median post-transfusion times of 120 [interquartile range (IQR); 45-180] and 360 (IQR; 285-320) min. Lactate, pyruvate, glycerol and glucose concentrations were measured with a bedside analyzer, and the lactate/pyruvate (LP) ratio was calculated automatically. RESULTS: RBC transfusions decreased the LP ratio from (T0) 18.80 [interquartile range (IQR); 14.85-27.45] to (T1a) 17.80 (IQR; 14.35-25.20; P < 0.05) and (T1b) 17.90 (IQR; 14.45-22.75; P < 0.001), while there was also significant interindividual variation. Post-transfusion LP ratio changes at T1a [r = -0.42; 95 % confidence interval (CI), -0.66 to -0.098; P = 0.01] and T1b (r = -0.68; 95 % [CI], -0.82 to -0.44; P < 0.001) were significantly correlated with the pre-transfusion LP ratio, but not with baseline demographic characteristics, vital signs, severity scores, hemoglobin level and blood lactate. RBC storage time and leukocyte reduction had no influence on the tissue metabolic response to transfusion. CONCLUSIONS: Tissue oxygenation is affected by RBC transfusion in critically ill septic patients. Monitoring of tissue LP ratio by microdialysis may represent a useful method for individual clinical management.

Evaluation of the role of the new INNOVANCE PFA P2Y test cartridge in detection of clopidogrel resistance.

Light transmittance aggregometry (LTA) has been extensively used in monitoring clopidogrel therapy. However, the availability of simple and rapid point-of-care platelet function assays is of great clinical importance. Thus, the manufacturer of the Platelet Function Analyzer (PFA)-100 System has recently produced the INNOVANCE PFA P2Y test cartridge. We assessed the ability of this new test to reliably detect clopidogrel resistance. We enrolled 90 consecutive patients with coronary artery disease receiving chronic clopidogrel maintenance therapy in combination with aspirin. Twenty healthy volunteers served as controls. Clopidogrel resistance was simultaneously analysed by the INNOVANCE PFA P2Y test cartridge, ADP-induced LTA, the flow-cytometric vasodilator-stimulated phosphoprotein (VASP)-phosphorylation assay and the multiple electrode aggregometry (Multiplate). Agreement among the four platelet function methods by two was assessed using Cohen's kappa coefficient. According to the cut-off points for clopidogrel resistance proposed by the literature, agreement was fair between INNOVANCE PFA-100 P2Y and LTA (74.4%) and Multiplate (75.6%), while poor agreement was noticed in VASP assay (63.3%). Based on cut-off points indicating a higher thrombotic risk, agreement between the PFA-100 System and the other three methods did not significantly differ compared to the previous cut-offs (72.2%, 71.1% and 55.1%, respectively). The INNOVANCE PFA-100 P2Y test seems to be comparable to other established platelet function assays in detecting clopidogrel resistance. However, the modest agreement among platelet function methods makes the performance of platelet function testing crucial with more than one technique in order to reliably identify poor responders to clopidogrel treatment.

Thrombomodulin as a regulator of the anticoagulant pathway: implication in the development of thrombosis.

Thrombomodulin is a cell surface-expressed glycoprotein that serves as a cofactor for thrombin-mediated activation of protein C (PC), an event further amplified by the endothelial cell PC receptor. The PC pathway is a major anticoagulant mechanism that downregulates thrombin formation and hedges thrombus formation. The objectives of this review were to review recent findings regarding thrombomodulin structure, its involvement in the regulation of hemostasis and further discuss the implication, if any, of the genetic polymorphisms in the thrombomodulin gene in the risk of development of thrombosis. We performed a literature search by using electronic bibliographic databases. Although the direct evaluation of risk situations associated with thrombomodulin mutations/polymorphisms could be of clinical significance, it appears that mutations that affect the function of thrombomodulin are rarely associated with venous thromboembolism. However, several polymorphisms are reported to be associated with increased risk for arterial thrombosis. Additionally studies on knock out mice as well studies on humans bearing rare mutations suggest that thrombomodulin dysfunction may be implicated in the pathogenesis of myocardial infraction.

Angiotensin converting enzyme (ACE) insertion/deletion (I/D) polymorphism and circulating ACE levels are not associated with outcome in critically ill septic patients.

BACKGROUND: In critically ill patients independent studies have shown contradictory findings regarding the prognostic significance of the D/D genotype of the I/D angiotensin converting enzyme (ACE) polymorphism. The study aim was to evaluate the effect of both ACE I/D polymorphism and ACE serum levels on the clinical outcomes of critically ill septic patients. METHODS: This study recruited 186 Caucasian patients with sepsis, severe sepsis or septic shock. Epidemiological, clinical data, co-morbidities and severity scores were recorded. Measurements of serum ACE activity and genotyping for ACE I/D polymorphism were carried out. Primary outcomes were the 28- and the 90-day mortality; secondary outcomes included the number of days without renal or cardiovascular failure and ventilation-free days over the 28-day period following study enrolment. RESULTS: Neither 28- nor 90-day mortality were associated with ACE I/D polymorphism (p=0.59 and 0.34, respectively) or circulating ACE levels (p=0.17 and 0.25, respectively). Similarly, ACE polymorphism and levels were not related to ventilation-free days (p=0.14 and 0.25, respectively), days without cardiovascular failure (p=0.14 and 0.81, respectively) and days without renal failure (p=0.64 and 0.27, respectively). CONCLUSIONS: Neither ACE I/D polymorphism nor serum ACE levels seem to be significant prognostic factors of clinical outcomes in septic, critically ill patients.

Do different substitution patterns or plant origin in hydroxyethyl starches affect blood coagulation in vitro?

The effect of hydroxyethyl starches (HES) on blood coagulation is affected by their molecular weight, their molar substitution and the C2/C6 ratio. The solutions of 6% HES 130/0.4 and 6% HES 130/0.42 have similar molecular weight and molar substitution but different C2/C6 ratio and plant origin. In the present study, the comparative effect of 6% HES 130/0.4 versus 6% HES 130/0.42 on blood coagulation was investigated in vitro. Thirty milliliter of blood was obtained from 10 healthy volunteers and was diluted by 10, 30 and 50% using either 6% HES 130/0.4 or HES 130/0.42, respectively. Blood coagulation was assessed using thrombelastography measurements (clotting time, clot formation time, maximal clot firmness and alpha-angle). The assessment of platelet function was performed with whole blood aggregometry after adding thrombin-receptor-activating protein. No differences were noted between respective dilutions of the two HES. Both colloids produced significant reductions below the reference values range in clotting time at 10, 30 and 50% dilutions. The 50% dilution of both colloids resulted in significant reduction of maximal clot firmness, alpha-angle and platelet aggregation. The present study showed that the corn-derived 6% HES 130/0.4 and the potato-derived 6% HES 130/0.42 have the same effect on blood coagulation in vitro.

The effect of four hemostatic gene polymorphisms on the outcome of septic critically ill patients.

Genetic variants of hemostatic factors leading to prothrombotic phenotypes of hypercoagulability and hypofibrinolysis might affect prognosis of septic critically ill patients. Our aim was to evaluate the effect of four hemostatic genetic variants, namely fibrinogen-beta-455G/A, factor XIII (FXIII) V34L, plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphisms and factor V Leiden (FVL) mutation on survival of critically ill patients with severe sepsis or septic shock. A prospective, observational study in an 18-bed general ICU included 73 patients with severe sepsis or septic shock. Epidemiological, laboratory data and comorbidities along with severity scores were recorded. Genotyping for fibrinogen-beta-455G/A, FXIII V34L and PAI-1 4G/5G polymorphism and FVL mutation was carried out in all patients. The primary outcomes were the 28-day and the 90-day survival. Age, septic shock, severity indexes, prior steroid use and arterial pH were identified as predictors of the 28-day and 90-day survival in both the univariate and the multivariate models. On the contrary, none of the examined polymorphisms was found to significantly affect either the 28-day or the 90-day survival. Our data suggest that the importance of these hemostatic polymorphisms as predictors of the prognosis of sepsis in critically ill patients is probably very small.

Reduced carriership of 4G allele of plasminogen activator inhibitor-1 4G/5G polymorphism in very young survivors of myocardial infarction.

There are limited and controversial data regarding the impact of 4G/5G polymorphism of the plasminogen activator inhibitor-1 (PAI-1) gene in the pathogenesis of premature myocardial infarction (MI). We explored whether 4G/5G polymorphism of the PAI-1 gene is associated with the development of MI

G-455A polymorphism of beta-fibrinogen gene and the risk of premature myocardial infarction in Greece.

INTRODUCTION: There are limited and controversial data regarding the impact of G-455A polymorphism of beta-fibrinogen gene in the pathogenesis of premature myocardial infarction (MI). We examined whether the G-455A polymorphism of beta-fibrinogen gene is associated with the development of MI< or =35 years of age. METHODS: We recruited 181 consecutive patients who had survived their first acute MI< or =35 years of age (mean age=32.2+/-3.4 years). The control group consisted of 129 healthy individuals matched with cases for age and sex, without a family history of premature coronary heart disease. G-455A polymorphism of beta-fibrinogen was tested with polymerase chain reaction and reverse hybridization. RESULTS: There was a higher prevalence of carriers of the A allele (GA+AA genotype) in controls than in patients (odds ratio [OR] 0.57, 95% confidence interval [CI] 0.36 to 0.91, p=0.02). G-455A polymorphism of beta-fibrinogen gene was associated with lower risk for acute MI (OR 0.46, 95% CI 0.25 to 0.83, p=0.01) after adjusting for major cardiovascular risk factors. Fibrinogen levels were higher in patients compared to controls [332 (292-385) vs. 311 (262-373) mg/dL, p=0.01], but the adjusted for classical risk factors fibrinogen levels did not differ (OR 1.003, 95% CI 0.99 to 1.01, p=0.37). Patients possessing the A allele did not differ in their fibrinogen and lipid levels compared to patients with the -455GG genotype. CONCLUSIONS: Our data indicate that the presence of the G-455A polymorphism of beta-fibrinogen gene has a "protective effect" against the development of non-fatal acute MI< or =35 years of age in Greece.

Evaluation of a reverse-hybridization StripAssay for the detection of genetic polymorphisms leading to acenocoumarol sensitivity.

Acenocoumarol is mainly catabolized by CYP2C9 isoform of cytochrome P450 (CYP) liver complex and exerts its anticoagulant effect through the inhibition of Vitamin K Epoxide Reductase (VKOR). The most important genetic polymorphisms which lead to an impaired enzymatic activity and therefore predispose to acenocoumarol sensitivity, are considered to be CYP2C9*2 (Arg144Cys), CYP2C9*3 (Ile359Leu) and VKORC1-1639G>A, respectively. In this study we compared the results of the PGXThrombo StripAssay kit (ViennaLab Diagnostics,Vienna, Austria) with direct DNA sequencing and in house Restriction Fragment Length Polymorphisms (RFLP) for the detection of the aforementioned Single Nucleotide Polymorphisms (SNPs). The reverse hybridization StripAssay was found to be equally effective with RFLP and direct DNA sequencing for the detection of CYP2C9*2 and CYP2C9*3 polymorphisms, respectively. The comparison of the RFLP reference method with the reverse hybridization StripAssay for the detection of VKORC1-1639 G>A polymorphism showed that the reverse hybridization StripAsssay might misclassify some A/A homozygotes as heterozygotes. Optimization of the hybridization procedures may eliminate the extra low signal band observed in some samples at the reverse hybridization StripAssay and improve its diagnostic value.

The role of the Platelet Function Analyzer (PFA)-100 and platelet aggregometry in the differentiation of essential thrombocythemia from reactive thrombocytosis.

INTRODUCTION: The most crucial component of all diagnostic criteria for essential thrombocythemia (ET) has been the exclusion of reactive thrombocytosis (RT). Our aim was to evaluate the diagnostic performance of the PFA-100 collagen-epinephrine (CEPI) cartridge test and epinephrine-induced aggregometry individually, but mainly combined, in the differentiation of ET from RT. MATERIALS AND METHODS: 26 patients with ET and 25 with RT were studied. Platelet function was analyzed by the PFA-100 and by light transmission aggregometry with epinephrine and ADP. The JAK2 mutational status was identified and hematological parameters, plasma von Willebrand factor antigen and activity levels were also assessed. RESULTS: The sensitivity (Se), specificity (Sp), positive predictive value (PPV), and the negative predictive value (NPV) of PFA-100 CEPI vs epinephrine-induced aggregometry in the differentiation of ET from RT were estimated as follows: Se (%): 78.9 vs 84.6, Sp (%): 92.0 vs 96.0, PPV (%): 88.2 vs 95.7, NPV (%): 85.2 vs 85.7, respectively. When both of these methods were combined, a lower sensitivity of 68.4%, but a specificity of 100% was attained. The PPV observed with this double abnormal combination was 100% and the NPV 80.6%. Lastly, when we assessed the abnormality for either CEPI CT or epinephrine-induced aggregometry, the sensitivity was 100%, the specificity 88.0%, PPV 86.4% and NPV 100%. Thus, an abnormal combination was strongly suggestive of ET, while normal results with both methods excluded ET. CONCLUSIONS: If our results are replicated by further studies, these two methods could be used very effectively as adjunct markers in the differentiation between ET and RT.

The effect of plasma homocysteine levels on clinical outcomes of patients with acute lung injury/acute respiratory distress syndrome.

BACKGROUND: Several reports have shown that homocysteine promotes thrombosis by disturbing the procoagulant-anticoagulant balance, whereas alterations in coagulation and fibrinolysis have been suggested as important pathogenetic and prognostic determinants of mortality in acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). The objective of the study was to evaluate the effect of plasma homocysteine levels on the outcomes of patients with ALI/ARDS. METHODS: Sixty-nine consecutive ventilated patients with ALI/ARDS were studied. Blood samples were drawn within 3 days of clinical recognition of ARDS. Measurement of plasma homocysteine, vitamin B12, folate, creatinine, protein C and plasminogen-activator inhibitor-1 antigen levels, and genotyping of the methylenetetrahydrofolate reductase gene C677T and A1298C polymorphisms were carried out. The primary outcomes were 28- and 90-day mortality, whereas secondary outcomes included nonpulmonary organ failure-free days, liberation from mechanical ventilation up to day 28, and ventilator-free days during the 28 days after enrollment. RESULTS: In the multivariable analysis, plasma homocysteine concentration adjusted for age, Acute Physiology and Chronic Health Evaluation II score, methylenetetrahydrofolate reductase C677T and A1298C polymorphisms, and levels of plasminogen-activator inhibitor-1 antigen, protein C, creatinine, vitamin B12, and folate was not found to affect significantly mortality at 28 and 90 days (P = 0.39 and P = 0.83, respectively), days without organ failure besides lungs (P = 0.38), the probability of being free from mechanical ventilation at day 28 (P = 0.63), and days without ventilation assistance (P = 0.73). CONCLUSION: Our data suggest that increased plasma homocysteine levels, either alone or in synergy with other thrombophilic risk factors, do not seem to adversely affect the prognosis in patients with ALI/ARDS.

Portal, splenic and mesenteric vein thrombosis in a patient double heterozygous for factor V Leiden and prothrombin G20210A mutation.

We herein report a 56-year-old man who presented with abdominal pain, diarrhea and a 22-kg-weight loss over 4 months. He was on acenocoumarol treatment because of portal, splenic and mesenteric vein thrombosis (PSMVT) 3 months before, with admission international normalized ratio (INR):1.6. Doppler ultrasonography and helical computerized tomographic scan of the abdomen showed complete thrombosis of the extrahepatic portal vein extending into the superior mesenteric vein and splenic vein. The manifestation of thrombosis was in the absence of provocative stimuli or local cause. The patient had a negative history of venous thromboembolism. Thrombophilia workup revealed double heterozygosity for factor V Leiden and prothrombin G20210A mutation. He was immediately started with intravenous unfractionated heparin, followed by oral anticoagulation with target INR 2-3. Five days after a Doppler examination showed significant improvement in the flow within the portal vein, and a computerized tomographic scan of the abdomen 1 month later showed extensive recanalization of the portal venous system. The patient is now 36 months out from the second PSMVT episode and is doing well although maintaining oral lifelong anticoagulation. The case is of particular interest in that PSMVT was the first manifestation of this combined disorder. We conclude that all patients presenting with unexplained PSMVT should be investigated for the presence of a hypercoagulable state. Anticoagulation should be considered in all patients with this diagnosis and should be a lifelong therapy in those with an underlying thrombophilia.

Lack of association of angiotensin-converting enzyme insertion/deletion polymorphism and myocardial infarction at very young ages.

We examined whether angiotensin-converting enzyme (ACE) insertion (I)/deletion (D) polymorphism is associated with the development of myocardial infarction (MI) at < or = 35 years of age. The study sample consisted of 201 patients with premature MI and 140 age- and sex-matched healthy individuals. No difference was found in the distribution of ACE genotypes between the patients and controls. A higher prevalence of the DD genotype among hypertensives was found compared with the non-hypertensive patients (62.5% vs 35.6%, p = 0.01). ACE polymorphism is not associated with the development of premature MI and this might be due to the low prevalence of hypertension in young coronary patients.

Central retinal vein occlusion secondary to clomiphene treatment in a male carrier of factor V Leiden.

We report a case of a 35-year-old previously healthy man treated with clomiphene for infertility, who presented with blurred vision in his left eye due to ocular vein occlusion as documented by fluorescein angiography. The patient was heterozygous for the factor V Leiden (FV Leiden) mutation and for the 1298 A-C polymorphism of the methylene-tetrahydrofolate reductase (MTHFR) gene. He was treated with clopidogrel and is now free of symptoms. Because congenital thrombophilia is a moderate risk factor for central retinal vein occlusion and the administration of clomiphene may trigger this process, we recommend screening of young patients for FV Leiden before clomiphene treatment.