Polymorphisms of the tissue factor pathway inhibitor gene and the risk of restenosis after coronary angioplasty.

Intracoronary stent implantation is associated with a significantly lower risk of restenosis compared with balloon angioplasty. However, restenosis still occurs in some cases. Experimental studies suggest that the tissue factor pathway is involved in this phenomenon. We investigated a possible relationship between three previously identified polymorphisms of the tissue factor pathway inhibitor (TFPI) gene and restenosis in 443 patients who underwent angioplasty, with or without stent implantation. The effect of the intron 7-33T<--C polymorphism and that of the combined intron 7 and promoter genotype on plasma TFPI levels was also investigated in 58 healthy subjects. DNA analysis was performed by polymerase chain reaction amplification of genomic DNA extracted from white blood cells, followed by digestion with the restriction enzymes Hind III, Nde I and Mae III for the detection of promoter, intron 7 and exon IX polymorphisms, respectively. The minimal luminal diameter, percent stenosis, acute gain, late loss and loss index did not differ according to the genotype before, immediately after or 6 months after angioplasty, regardless of stent implantation. Interestingly, subjects with the intron 7 CC genotype had significantly higher total TFPI levels than those with the TT genotype before and after an enoxaparin injection. Moreover, subjects with the -287TT/Int7TT combined genotype had the lowest plasma TFPI levels. Despite significant variations in plasma TFPI levels, we found no evidence that three polymorphisms of the TFPI gene influence the risk of restenosis. These results do not exclude the possibility that other polymorphisms in the TFPI gene may influence this risk.

Polymorphism in the fractalkine receptor CX3CR1 as a genetic risk factor for coronary artery disease.

Coronary atherosclerosis is a major cause of death in industrialized countries. Monocytes, which play a key role in atherosclerosis, migrate into the vessel wall, presumably guided by specific chemoattractant and adhesion molecules. A compelling candidate for this role is the chemokine receptor CX3CR1, which is expressed on monocytes and acts as either a chemotactic receptor or an adhesion molecule, depending on whether its ligand, fractalkine, is presented free or membrane bound. A common variant of CX3CR1 was recently identified, encoded by the alleles I249 and M280, which form a common I(249)M(280) haplotype. When CX3CR1 genotypes were analyzed in 151 patients with acute coronary syndromes and in 249 healthy controls, CX3CR1 I249 heterozygosity was associated with a markedly reduced risk of acute coronary events, independent of established acquired coronary risk factors (eg, smoking, diabetes). The adjusted odds ratio for this allele was 0.43 (95% confidence interval, 0.26-0.72; P =.001). Consistent with this, functional analysis of peripheral blood mononuclear cells showed that CX3CR1 I249 heterozygosity was associated with a significant decrease in the number of fractalkine binding sites per cell. The results show that CX3CR1 I249 is an independent genetic risk factor for coronary artery disease and that CX3CR1 may be involved in the pathogenesis of atherosclerotic disease. (Blood. 2001;97:1925-1928)

A new T-287C polymorphism in the 5' regulatory region of the tissue factor pathway inhibitor gene. Association study of the T-287C and C-399T polymorphisms with coronary artery disease and plasma TFPI levels.

Tissue factor pathway inhibitor (TFPI) is an important regulator of the extrinsic blood coagulation pathway. We screened the untranslated 5' region of the TFPI gene for polymorphisms and investigated their possible involvement in arterial thrombosis. The allele frequencies of a new polymorphism, located 287 base pairs upstream of the transcription start site (T-287C), and that of the previously described C-399T polymorphism, were similar in cases and controls. In controls, the -287C allele was associated with significantly higher levels of total TFPI antigen, arguing for an effect of this polymorphism on TFPI gene expression. In controls, the C-399T polymorphism did not alter TFPI levels. In the cases, however, decreased total and post-heparin free TFPI levels and increased F1+2 levels were significantly associated with the -399T allele. These findings suggest that the T-287C and C-399T polymorphisms are not associated with an increased risk of coronary heart disease, a result which should be confirmed by a larger study. However, their influence on outcome, or a link with subtypes of acute coronary syndromes, cannot be excluded.

[Infection after total hip replacement by Staphylococcus caprae. Case report and review of the literature]. / Infection sur prothèse totale de hanche à Staphylococcus caprae. Cas clinique et revue de la littérature.

We report a case of Staphylococcus caprae bone and joint infection, that illustrate difficulties to diagnose coagulase-negative staphylococci (CNS) orthopedic surgery infections, specially following implantation of prostheses. Four of 5 strains successivelly isolated from deep and/or peri-operative specimens during late infection after total hip replacement (THR) have been identified, using commercial systems and conventionnal tests, as S. caprae. Identity of biochemical profile, antibiotype and pulsotype of the 4 isolates confirmed the pathogenicity of this animal CNS, rarely described as a human pathogen. Analysis of the 24 S. caprae human cases previously described evidence a relation ship between this bacteria and bone and joint infections, with implantation of prosthetic material as supplementary risk factor. S. caprae, whose major identification criteria are resumed, may have previously been misidentified as some similar CNS; this bacteria is probably part of our normal flora but may be recognized as an opportunistic pathogen, responsible for both nosocomial and community acquired infections.

Polymorphisms of the tissue factor pathway inhibitor (TFPI) gene in patients with acute coronary syndromes and in healthy subjects : impact of the V264M substitution on plasma levels of TFPI.

-Mutations of the gene encoding tissue factor pathway inhibitor (TFPI), an inhibitor of TF-induced activation of the coagulation cascade, were screened for in 130 patients and 142 healthy controls to determine whether these variants contribute to acute coronary syndromes or modify plasma TFPI levels. The following 3 new polymorphisms were identified: 384T-->C in exon IV, which does not change the corresponding amino acid (tyrosine 57); -33C-->T in intron 7 (the T/T, C/T, and C/C genotypes were found in approximately 50%, 40%, and 10% of subjects in both groups); and 874G-->A in exon IX (GTG-->ATG), which predicts a valine to methionine change (V264M) in the carboxy-terminus tail of TFPI. The V264M polymorphism was found in 9.2% of the cases and 4.9% of the controls; the associated odds ratio (OR) for acute coronary syndromes was 2.0 (95% confidence interval [CI], 0.7 to 5.1). The OR increased to 3.6 (95% CI, 0.8 to 15.7) and 3.2 (95% CI, 0.9 to 11.8) in nonsmokers and patients without other risk factors, respectively. The possible link between the V264M polymorphism and coronary heart disease was checked in a large case-control study of myocardial infarction (Etude Cas-Témoins de l'Infarctus du Myocarde [the ECTIM Study]). The results showed no link between the V264M polymorphism and coronary syndromes. Interestingly, however, 5 patients heterozygous for the V264M polymorphism had significantly lower plasma TFPI levels than did 13 patients with the most common genotype. Although our present results do not support an association between TFPI polymorphisms and acute coronary syndromes, the possibility that 1 of them, especially the exon IX polymorphism, is associated with subtypes of myocardial infarction or to evolutive particularities that were not assessed in this study, cannot be excluded and is currently being evaluated.

Development of a method to separate lipoprotein-bound and lipoprotein-depleted tissue factor pathway inhibitor. Measurement of free tissue factor pathway inhibitor activity.

The aim of this study was to develop a method to separate lipoprotein-bound from lipoprotein-free tissue factor pathway inhibitor (TFPI) and to measure the TFPI chromogenic activity and antigen in both fractions. This was performed by ultracentrifugation of plasma, after increasing its density to 1.21 g/ml with potassium bromide. Blood was taken from nine volunteers before and after an injection of low-molecular-weight heparin. The ultracentrifugation procedure was adequate, since the mean cholesterol recovery was 91% and only 2% of the cholesterol remained in the lipoprotein-depleted fraction. No free TFPI protein was found in the lipoprotein-rich fraction. Moreover, the amount of free TFPI in the lipoprotein-depleted fraction was close to that found in plasma. Using this method, we confirmed that heparin does not induce an increase in bound TFPI and that the moderate increase in total TFPI antigen in plasma is entirely caused by the enhancement of free TFPI. We then applied the TFPI chromogenic assay to the lipoprotein-depleted fraction to assess the activity of free TFPI. The activity was 0.11+/-0.03 and 0.36+/-0.08 U/ml before and after heparin, respectively (a 3.6-fold increase) while the activity of bound TFPI did not increase at all. We suggest that this method may be an alternative to gel filtration for measuring free TFPI activity, and might be of value in the search for TFPI abnormalities in patients with thrombosis.

Design and in vitro studies of a needle-type glucose sensor for subcutaneous monitoring.

A new miniaturized glucose oxidase based needle-type glucose microsensor has been developed for subcutaneous glucose monitoring. The sensor is equivalent in shape and size to a 26-guage needle (0.45-mm o.d.) and can be implanted with ease without any incision. The novel configuration greatly facilitates the deposition of enzyme and polymer films so that sensors with characteristics suitable for in vivo use (upper limit of linear range greater than 15 mM, response time less than 5 min, and sensitivity yielding a 5:1 signal-to-background ratio at normal basal glucose levels) can be prepared in high yield (greater than 60%). The sensor response is largely independent of oxygen tension in the normal physiological range. It also exhibits good selectivity against common interferences except for the exogenous drug acetaminophen.

In vitro and in vivo evaluation in dogs of a miniaturized glucose sensor.

A miniaturized glucose sensor was developed, consisting of a platinum wire entirely coated with teflon, except for a 1 mm section near its extremity where glucose oxidase is immobilized. The in vitro sensitivity to glucose of the sensors was 2.3 +/- 0.4 nA/mM, mean +/- SEM (n = 23). These sensors were implanted in the subcutaneous tissue of normal beagles. Two consecutive glucose infusions (15-30 mg/kg/min) were performed. The current generated by the sensor was used for calculation of the sensitivity coefficient (SC) (nA/mM), and the background current in the absence of glucose (lo) (nA). These parameters were used for determination of the apparent subcutaneous glucose concentration. The in vivo sensitivity was less than the in vitro sensitivity (0.5 +/- 0.1 vs. 2.2 +/- 0.2; n = 12 comparisons; p less than 0.01). Stability of sensor function was demonstrated by the absence in variation of SC and lo, calculated from the different plateaus obtained during the glucose infusions. This study provides a simple method for evaluating in vivo the function of a miniaturized sensor implanted in subcutaneous tissue.