Omer Aras

Elevated Whole-Blood Tissue Factor Procoagulant Activity as a Marker of Restenosis After Percutaneous Transluminal Coronary Angioplasty and Stent Implantation

Background—Experimental data suggest that tissue factor (TF) may induce neointimal hyperplasia after arterial injury. In this study, we investigated the hypothesis that elevated levels of TF in the circulation contribute to the development of restenosis after percutaneous transluminal coronary angioplasty (PTCA) or stent implantation. Methods and Results—Whole-blood TF procoagulant activity (TF-PCA) was measured using a previously described assay before, at 3 hours after, and at 24 hours after the intervention in 61 patients with stable angina undergoing PTCA (n=20) or stent implantation (n=41). Coronary angiography was performed 4 to 6 months after the intervention, and luminal narrowing ≥50% was defined as restenosis. Whole-blood TF-PCA levels did not correlate with intracellular monocyte tumor necrosis factor-&agr; expression, a marker of activation of these cells. Baseline levels and time course of whole-blood TF-PCA after the intervention were compared in patients who did or did not subsequently develop restenosis. Whole-blood TF-PCA levels did not change significantly in the 24 hours after either intervention. However, in both the PTCA and stent groups, initial TF-PCA was significantly higher in patients who subsequently developed restenosis (P =0.018 and 0.039 compared with those who did not develop restenosis for PTCA and stent groups, respectively). Conclusions—Higher baseline values of whole-blood TF-PCA may be a predictor of restenosis after PTCA and stent implantation.

Influence of 699C→T and 1080C→T polymorphisms of the cystathionine β‐synthase gene on plasma homocysteine levels

The association of moderately elevated total homocysteine (tHcy) levels with coronary artery disease is increasingly being recognized. However, the role of genetic influence on plasma tHcy levels is not completely understood. We studied 1 055 individuals with respect to the effect of two silent polymorphisms, the 699C→T and the 1080C→T, of the cystathionine β‐synthase (CBS) gene on plasma tHcy levels. Individuals who were heterozygous or homozygous for the T699 allele had lower post‐methionine load (PML) tHcy levels when compared to individuals with the C/C genotype. This association was statistically significant (p=0.005) for the T/T genotype compared to the C/C genotype and became even more significant (p=0.000002) when individuals carrying the 68‐bp insertion (844ins68) and the T1080 allele were excluded from the analysis. With regard to the 1080C→T polymorphism, the T1080 allele was associated with significantly lower PML tHcy levels only when individuals carrying the 844ins68 and T699 allele were excluded from the study (p=0.01 for 1080T/T genotype compared to 1080C/C genotype). We speculate that the 699C→T and 1080C→T polymorphisms may be in linkage disequilibrium with regulatory elements that upregulate CBS gene transcription.

Synthesis and Evaluation of a Series of 99mTc(CO)3+ Lisinopril Complexes for In Vivo Imaging of Angiotensin-Converting Enzyme Expression

In animal models of cardiac disease and in human congestive heart failure, expression of angiotensin-converting enzyme (ACE) is upregulated in the failing heart and has been associated with disease progression leading to cardiac failure and fibrosis. To develop probes for imaging ACE expression, a series of di(2-pyridylmethyl)amine (D) chelates capable of binding M(CO)3+ (M = technetium, rhenium) was conjugated to lisinopril by acylation of the ε-amine of the lysine residue with a series of di(2-pyridylmethylamino)alkanoic acids where the distance of the chelator from the lisinopril core was investigated by varying the number of methylene spacer groups to produce di(2-pyridylmethyl)amine(Cx)lisinopril analogs: D(C4)lisinopril, D(C5)lisinopril, and D(C8)lisinopril. The inhibitory activity of each rhenium complex was evaluated in vitro against purified rabbit lung ACE and was shown to vary directly with the length of the methylene spacer: Re[D(C8)lisinopril], inhibitory concentration of 50% (IC50) = 3 nM; Re[D(C5)lisinopril], IC50 = 144 nM; and Re[D(C4)lisinopril], IC50 = 1,146 nM, as compared with lisinopril, IC50 = 4 nM. The in vivo specificity for ACE was determined by examining the biodistribution of the 99mTc-[D(C8)lisinopril] analog in rats with and without pretreatment with unlabeled lisinopril. Uptake in the lungs, a tissue that constitutively expresses ACE, was 15.2 percentage injected dose per gram at 10 min after injection and was dramatically reduced by pretreatment with lisinopril, supporting ACE-mediated binding in vivo. Planar anterior imaging analysis of 99mTc-[D(C8)lisinopril] corroborated these data. Thus, high-affinity 99mTc-labeled ACE inhibitor has been designed with potency similar to that of lisinopril and has been demonstrated to specifically localize to tissues that express ACE in vivo. This agent may be useful in monitoring ACE as a function of disease progression in relevant diseases such as heart failure.

Stored platelets contain residual amounts of tissue factor: evidence from studies on platelet concentrates stored for prolonged periods

BACKGROUND: The advent of new strategies for pathogen reduction has raised the question of whether platelet (PLT) concentrates (PCs) exposed to longer periods of storage retain adequate hemostatic function.

Relation between the insertion/deletion polymorphism of the angiotensin I converting enzyme gene and restenosis after coronary stenting.

Background Observations with intravascular ultrasound demonstrated that neointimal hyperplasia is the predominant factor responsible for in-stent restenosis. Experimental data suggest that angiotensin I converting enzyme (ACE) plays a role in the thickening of neointima after balloon denudation. Insertion/deletion (I/D) polymorphism of the ACE gene is significantly associated with plasma level of ACE and subjects with D/D genotype have significantly higher plasma levels of ACE than normal. Objective To investigate whether this polymorphism influences the risk of restenosis after coronary stenting. Methods We genotyped 158 patients who had undergone single-vessel coronary stenting for the ACE I/D polymorphism. Results Of the 158 patients, 56 (35%) had the D/D genotype, 71 (45%) had the I/D genotype and 31(20%) had the I/I genotype. Prevalences of genotypes were compatible with Hardy-Weinberg equilibrium and distributions of ACE genotype among patients and 132 healthy controls from the same geographic area did not differ. At follow-up (after a median duration of 5.4 months), overall rates of angiographic restenosis and of revascularization of target lesion (RTL) were 32.3 and 22.8%, respectively. Of 51 patients with angiographic restenosis, 31 (60.8%) had focal and 20 (39.2%) had diffuse patterns of restenosis. Diffuse in-stent restenosis was significantly more prevalent among patients with D/D genotype (P= 0.016). Multiple stepwise logistic regression analysis identified ACE I/D polymorphism as the independent predictor of angiographic restenosis and RTL. Relative risk of angiographic restenosis was 6.29 [95% confidence interval (CI), 1.80–22.05, P= 0.0004] for D/D genotype and 3.88 (95% CI 1.11–13.12, P= 0.029) for I/D genotype, whereas relative risk of RTL was 7.44 (95% CI 1.60–34.58, P= 0.01) for D/D genotype and 3.88 (95% CI 0.083–18.15, P= 0.085) for I/D genotype. Conclusions The ACE I/D polymorphism is significantly associated with risk of angiographic and clinical restenosis after coronary stenting. Angiographic pattern of restenosis is also significantly associated with I/D polymorphism, diffuse type being more prevalent among subjects with D/D genotype.

Factor V Leiden and Inflammation

Factor V Leiden, is a variant of human factor V (FV), also known as proaccelerin, which leads to a hypercoagulable state. Along these years, factor V Leiden (FVL) has been studied from the pathophysiologic point of view, and research has been focused on finding clinical approaches for the management of the FVL associated to a trombophilic state. Less attention has been paid about the possible role of FVL in inflammatory conditions known to be present in different disorders such as uremia, cirrhosis, liver transplantation, depression as well as sepsis, infection or, inflammatory bowel disease (IBD). Whether platelet FVL will increase the activation of coagulation and/or in which proportion is able to determine the final outcome in the previously mentioned inflammatory conditions is a subject that remains uncertain. This paper will review the association of FVL with inflammation. Specifically, it will analyze the important role of the endothelium and the contribution of other inflammatory components involved at both the immune and vascular levels. This paper will also try to emphasize the importance of being a FVL carrier in associations to diseases where a chronic inflammation occurs, and how this condition may be determinant in the progression and outcome of a specific clinic situation.