Circulating tissue factor and microparticles are not increased in patients with deep vein thrombosis.

BACKGROUND: Circulating tissue factor (TF) is associated with inflammation and may contribute to thrombotic events. Aim of this study was to analyze circulating TF activity and proinflammatory cytokines in patients with deep venous thrombosis. PATIENTS AND METHODS: Forty-eight patients with deep vein thrombosis and 45 control subjects were included. Venous blood samples were obtained at diagnosis for analysis of TF activity, TF antigen, prothrombin fragment F1 + 2, microparticles (expressing phosphatidylserine and supporting FXa generation), Interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12 and tumor-necrosis-factor-alpha (TNF). RESULTS: TF antigen, activity and microparticles were similar in both groups: In contrast, a significant increase in plasma IL-6, IL-8 and F1 + 2 levels was found in thrombosis. This increase in IL-6 and IL-8 as well as F1 + 2 was not correlated with the extent of thrombosis, predisposing factors or onset of symptoms. CONCLUSIONS: Circulating TF and microparticles are not elevated in deep venous thrombosis. The increase in IL-6, IL-8 and F1 + 2 during thrombosis was not proportional to the extent or predisposing risk factors.

PlA polymorphism of platelet glycoprotein IIIa and risk of restenosis after coronary stent placement.

BACKGROUND: Platelets play a central role in the process of restenosis after percutaneous coronary interventions. A polymorphism of platelet glycoprotein IIIa (PlA) has been associated with a higher risk of coronary thrombosis. We designed this prospective study to test the hypothesis that PlA polymorphism of glycoprotein IIIa is associated with an increased risk for restenosis after coronary stent placement. METHODS AND RESULTS: The study included 1150 consecutive patients with successful coronary stent placement and 6-month follow-up with coronary angiography. The end point of the study was the incidence of angiographic restenosis (>/=50% diameter stenosis) at follow-up. Of the 1150 patients, 72.5% were homozygous for PlA1, 24.7% were heterozygous (PlA1/A2), and 2.8% were homozygous for PlA2. Patients with the PlA2 allele demonstrated a significantly higher restenosis rate than did those without (47% versus 38%; OR, 1.42; 95% CI, 1.09 to 1.84). The risk was highest in homozygous carriers of PlA2 (53.1% restenosis rate). After adjustment for several clinical and angiographic characteristics, the presence of the PlA2 allele remained a significantly independent risk factor for restenosis (adjusted OR, 1.35; 95% CI, 1.07 to 1.70). The influence of the PlA2 allele on restenosis was stronger in women. Women with PlA2 had a restenosis rate of 52% compared with the 33% incidence among women homozygous for PlA1 (OR, 2.21; 95% CI, 1.27 to 3.85). CONCLUSIONS: This study showed a significant association between the PlA polymorphism of glycoprotein IIIa and the risk of restenosis after coronary stent placement. The risk was more pronounced in patients homozygous for PlA2 allele and in female patients.

PlA polymorphism of glycoprotein IIIa and risk of adverse events after coronary stent placement.

OBJECTIVE: We designed this prospective study to test the hypothesis that platelet antigen (PlA) polymorphism of glycoprotein (GP) IIIa is associated with an increased risk for adverse events after coronary stent placement. BACKGROUND: Platelets play a central role in arterial thrombosis. The PlA polymorphism of GP IIIa, a constituent of the fibrinogen receptor, may influence the platelet function and, thereby, the early outcome of patients after coronary stent placement. METHODS: The study included 1,759 consecutive patients with stable or unstable angina and successful coronary stent placement. Platelet antigen genotypes were determined by allele-specific restriction enzyme analysis. The end point of the study was a composite of death, myocardial infarction and urgent revascularization during the first 30 days after stent placement. RESULTS: The PlA1 genotype of the patients included was: 70.2% were homozygous for platelet antigen 1 (PlA1), 2.6% homozygous for platelet antigen 2 (PlA1), and 27.2% were heterozygous (PlA1/A2). The incidence of the composite end point was 5.5% among PlA2 carriers and 5.4% in homozygous PlA1 subjects (p = 0.94). It was 5.4% in PlA1/A1 patients, 4.8% in PlA1/A2 patients and 13.0% in PlA2A2 patients (p = 0.06). The combined incidence of death or myocardial infarction was 4.3% in PlA1/A1 patients, 4.2% in PlA1/A2 patients and 13.0% in PlA2/A2 patients (p = 0.02). CONCLUSIONS: The isolated presence of the PlA2 allele in heterozygous patients is not associated with any detectable increase in the risk for an adverse 30-day outcome after coronary stenting. This study suggests also that an increased risk is likely to be present in homozygous carriers of the PlA2 allele, but this should be confirmed in a much larger series of patients.

HPA-1 and HPA-3 polymorphisms of the platelet fibrinogen receptor and coronary artery disease and myocardial infarction.

Platelet fibrinogen receptor (glycoprotein [GP] IIb/IIIa) plays a fundamental role in atherothrombosis. The human platelet antigen (HPA) -1 and the HPA-3 are the most extensively studied polymorphisms of GPIIIa and GPIIb, respectively. This study was designed to test, in a large population, the hypothesis that these polymorphisms represent a risk factor for the occurrence of coronary artery disease (CAD) and myocardial infarction (MI). Consecutive, angiographically examined patients with significant coronary stenoses but without symptoms or signs of old or acute MI constituted the group with CAD (CAD, n = 998) and those with old or acute MI constituted the group with MI (MI, n = 793). As controls served subjects, matched with patients for age and sex, with neither angiographic CAD nor symptoms or signs of MI (matched controls [MC], n = 340) as well as a group of blood donors without cardiac symptoms or signs of CAD (BD, n = 104). Genotype distribution was similar across the groups; HPA-1a/a: HPA-1a/b: HPA-1b/b was 75.0%: 22.1%: 2.9% in BD, 72.6%: 24.7%: 2.6% in MC, 70.5%: 26.8%: 2.7% in CAD, and 70.7%: 26.4%: 2.9% in MI; HPA-3a/a: HPA-3a/b: HPA-3b/b was 39.4%: 40.4%: 20.2% in BD, 33.5%: 50.0%: 16.5% in MC, 35.0%: 46.4%: 17.0% in CAD, and 37.1%: 48.0%: 16.5% in MI. There was no interaction between these polymorphisms, nor between each of these polymorphisms and other risk factors. Thus, the HPA-1 and HPA-3 polymorphisms are neither separately nor in concert associated with any measurable increase of the risk for CAD or MI in angiographically evaluated subjects.

Characterization of the catalytic domain of Clostridium novyi alpha-toxin.

Clostridium novyi alpha-toxin belongs to the family of large clostridial cytotoxins which act on cells through the modification of small GTP-binding proteins. We present here an analysis of the catalytic domain of alpha-toxin. A NH(2)-terminal 551-amino-acid fragment, alpha 551, was found to contain the full enzyme activity of the holotoxin, whereas a slightly shortened fragment encompassing 509 amino acids showed no detectable enzyme activity. Further characterization of the enzymatically active fragment alpha 551 revealed a substrate specificity for both UDP-N-acetylglucosamine and UDP-glucose. A Michaelis-Menten constant of 17 microM was determined for the substrate UDP-N-acetylglucosamine, while that for UDP-glucose was about 20 times higher, indicating a weaker affinity of the toxin for the latter substrate. Mutation of the aspartic acids of a conserved motif DXD within alpha 551 reduced enzyme activity >700-fold and inhibited cytotoxicity after microinjection in cells. Inhibition of enzyme activity of the DXD mutant could be partially overcome by increased concentrations of manganese ions, suggesting the involvement of these aspartic acids in Mn(2+) binding. By construction of chimeras of enzymatically active fragments of C. sordellii lethal toxin and C. novyi alpha-toxin, we located the region involved in nucleotide-sugar specificity to amino acids 133 through 517.