Cardiologie. Tests de réactivité plaquettaire: mise à jour pour le praticien [Cardiology. Platelet function testing for clinicians].

Platelet P2YI2 receptor inhibition with clopidogrel, prasugrel or ticagrelor plays a key role to prevent recurrent ischaemic events after percutaneous coronary intervention in acute coronary syndromes or elective settings. The degree of platelet inhibition depends on the antiplatelet medication used and is influenced by clinical and genetic factors. A concept of therapeutic window exists. On one side, efficient anti-aggregation is required in order to reduce cardio-vascular events. On the other side, an excessive platelet inhibition represents a risk of bleeding complications. This article describes the current knowledge about some platelet function tests and genetic tests and summarises their role in the clinical practice.

Fusaric acid-producing strains of Fusarium oxysporum alter 2,4-diacetylphloroglucinol biosynthetic gene expression in Pseudomonas fluorescens CHA0 in vitro and in the rhizosphere of wheat.

The phytotoxic pathogenicity factor fusaric acid (FA) represses the production of 2,4-diacetylphloroglucinol (DAPG), a key factor in the antimicrobial activity of the biocontrol strain Pseudomonas fluorescens CHA0. FA production by 12 Fusarium oxysporum strains varied substantially. We measured the effect of FA production on expression of the phlACBDE biosynthetic operon of strain CHA0 in culture media and in the wheat rhizosphere by using a translational phlA'-'lacZ fusion. Only FA-producing F. oxysporum strains could suppress DAPG production in strain CHA0, and the FA concentration was strongly correlated with the degree of phlA repression. The repressing effect of FA on phlA'-'lacZ expression was abolished in a mutant that lacked the DAPG pathway-specific repressor PhlF. One FA-producing strain (798) and one nonproducing strain (242) of F. oxysporum were tested for their influence on phlA expression in CHA0 in the rhizosphere of wheat in a gnotobiotic system containing a sand and clay mineral-based artificial soil. F. oxysporum strain 798 (FA(+)) repressed phlA expression in CHA0 significantly, whereas strain 242 (FA(-)) did not. In the phlF mutant CHA638, phlA expression was not altered by the presence of either F. oxysporum strain 242 or 798. phlA expression levels were seven to eight times higher in strain CHA638 than in the wild-type CHA0, indicating that PhlF limits phlA expression in the wheat rhizosphere.

Long-term outcome of idiopathic steroid-resistant nephrotic syndrome: a multicenter study.

Long-term outcome of idiopathic steroid-resistant nephrotic syndrome was retrospectively studied in 78 children in eight centers for the past 20 years. Median age at onset was 4.4 years (1.1-15.0 years) and the gender ratio was 1.4. Median follow-up period was 7.7 years (1.0-19.7 years). The disease in 45 patients (58%) was initially not steroid-responsive and in 33 (42%) it was later non-responsive. The main therapeutic strategies included administration of ciclosporine (CsA) alone (n = 29; 37%) and CsA + mycophenolate mofetil (n = 18; 23%). Actuarial patient survival rate after 15 years was 97%. Renal survival rate after 5 years, 10 years and 15 years was 75%, 58% and 53%, respectively. An age at onset of nephrotic syndrome (NS) > 10 years was the only independent predictor of end-stage renal disease (ESRD) in a multivariate analysis using a Cox regression model (P < 0.001). Twenty patients (26%) received transplants; ten showed recurrence of the NS: seven within 2 days, one within 2 weeks, and two within 3-5 months. Seven patients lost their grafts, four from recurrence. Owing to better management, kidney survival in idiopathic steroid-resistant nephrotic syndrome (SRNS) has improved during the past 20 years. Further prospective controlled trials will delineate the potential benefit of new immunosuppressive treatment.

Lack of angiotensin I accumulation after converting enzyme blockade by enalapril or lisinopril in man.

In nine normal volunteers, a series of five venous blood samples was obtained before and up to 24 h after converting enzyme inhibition by a single oral dose of enalapril or lisinopril. Plasma renin activity and blood angiotensin I were measured. A close linear relationship was found between the increase in plasma renin activity and the increase in blood angiotensin I. The linear correlation between plasma renin activity and blood angiotensin I remained after converting enzyme inhibition. Thus, the rise in angiotensin I after inhibition of the conversion of angiotensin I to angiotensin II is due to an enhanced release of renin rather than to accumulation of angiotensin I.

Radiotherapy and temozolomide for newly diagnosed glioblastoma: recursive partitioning analysis of the EORTC 26981/22981-NCIC CE3 phase III randomized trial.

PURPOSE: The European Organisation for Research and Treatment of Cancer and National Cancer Institute of Canada trial on temozolomide (TMZ) and radiotherapy (RT) in glioblastoma (GBM) has demonstrated that the combination of TMZ and RT conferred a significant and meaningful survival advantage compared with RT alone. We evaluated in this trial whether the recursive partitioning analysis (RPA) retains its overall prognostic value and what the benefit of the combined modality is in each RPA class. PATIENTS AND METHODS: Five hundred seventy-three patients with newly diagnosed GBM were randomly assigned to standard postoperative RT or to the same RT with concomitant TMZ followed by adjuvant TMZ. The primary end point was overall survival. The European Organisation for Research and Treatment of Cancer RPA used accounts for age, WHO performance status, extent of surgery, and the Mini-Mental Status Examination. RESULTS: Overall survival was statistically different among RPA classes III, IV, and V, with median survival times of 17, 15, and 10 months, respectively, and 2-year survival rates of 32%, 19%, and 11%, respectively (P < .0001). Survival with combined TMZ/RT was higher in RPA class III, with 21 months median survival time and a 43% 2-year survival rate, versus 15 months and 20% for RT alone (P = .006). In RPA class IV, the survival advantage remained significant, with median survival times of 16 v 13 months, respectively, and 2-year survival rates of 28% v 11%, respectively (P = .0001). In RPA class V, however, the survival advantage of RT/TMZ was of borderline significance (P = .054). CONCLUSION: RPA retains its prognostic significance overall as well as in patients receiving RT with or without TMZ for newly diagnosed GBM, particularly in classes III and IV.

Simultaneous determination of human plasma levels of citalopram, paroxetine, sertraline, and their metabolites by gas chromatography-mass spectrometry.

A gas chromatography-mass spectrometry method is presented which allows the simultaneous determination of the plasma concentrations of the selective serotonin reuptake inhibitors citalopram, paroxetine, sertraline, and their pharmacologically active N-demethylated metabolites (desmethylcitalopram, didesmethylcitalopram, and desmethylsertraline) after derivatization with the reagent N-methyl-bis(trifluoroacetamide). No interferences from endogenous compounds are observed following the extraction of plasma samples from six different human subjects. The standard curves are linear over a working range of 10-500 ng/mL for citalopram, 10-300 ng/mL for desmethylcitalopram, 5-60 ng/mL for didesmethylcitalopram, 20-400 ng/mL for sertraline and desmethylsertraline, and 10-200 ng/mL for paroxetine. Recoveries measured at three concentrations range from 81 to 118% for the tertiary amines (citalopram and the internal standard methylmaprotiline), 73 to 95% for the secondary amines (desmethylcitalopram, paroxetine and sertraline), and 39 to 66% for the primary amines (didesmethylcitalopram and desmethylsertraline). Intra- and interday coefficients of variation determined at three concentrations range from 3 to 11% for citalopram and its metabolites, 4 to 15% for paroxetine, and 5 to 13% for sertraline and desmethylsertraline. The limits of quantitation of the method are 2 ng/mL for citalopram and paroxetine, 1 ng/mL for sertraline, and 0.5 ng/mL for desmethylcitalopram, didesmethylcitalopram, and desmethylsertraline. No interferences are noted from 20 other psychotropic drugs. This sensitive and specific method can be used for single-dose pharmacokinetics. It is also useful for therapeutic drug monitoring of these three drugs and could possibly be adapted for the quantitation of the two other selective serotonin reuptake inhibitors on the market, namely fluoxetine and fluvoxamine.

No longitudinal mitochondrial DNA sequence changes in HIV-infected individuals with and without lipoatrophy.

The potential for mitochondrial (mt) DNA mutation accumulation during antiretroviral therapy (ART), and preferential accumulation in patients with lipoatrophy compared with control participants, remains controversial. We sequenced the entire mitochondrial genome, both before ART and after ART exposure, in 29 human immunodeficiency virus (HIV)-infected Swiss HIV Cohort Study participants initiating a first-line thymidine analogue-containing ART regimen. No accumulation of mtDNA mutations or deletions was detected in 13 participants who developed lipoatrophy or in 16 control participants after significant and comparable ART exposure (median duration, 3.3 and 3.7 years, respectively). In HIV-infected persons, the development of lipoatrophy is unlikely to be associated with accumulation of mtDNA mutations detectable in peripheral blood.

Prostate cancer: F-18-fluorocholine PET-CT utility. [Cancer de la prostate : utilité de la TEP-TDM à la 18F-fluorocholine.]

In oncology, positron emission computed tomography (PET/CT) has become an essential tool for initial staging, response evaluation and follow-up of cancer patients. Most of the frequent tumors (lung, breast, esophagus, and lymphomas) are highly avid for (18)F-fluorodeoxyglucose ((18)FDG), but prostate cancer has not demonstrated significant uptake of FDG. The development of new tracers labeled with (18)F such as choline analogs allowed already to obtain interesting results particularly in patients with biological relapse and inconclusive conventional imaging workup. The impact of (18)F-flurocholine PET/CT on patient management needs to be validated in large studies, but many centers use already this examination in order to guide further management, including radiotherapy planning. (C) 2011 Elsevier Masson SAS. All rights reserved.

Toxicity of triclosan, penconazole and metalaxyl on Caulobacter crescentus and a freshwater microbial community as assessed by flow cytometry.

Biocides are widely used for domestic hygiene, agricultural and industrial applications. Their widespread use has resulted in their introduction into the environment and raised concerns about potential deleterious effects on aquatic ecosystems. In this study, the toxicity of the biocides triclosan, penconazole and metalaxyl were evaluated with the freshwater bacterium Caulobacter crescentus and with a freshwater microbial community using a combination of single- and double-stain flow cytometric assays. Growth of C.  crescentus and the freshwater community were repressed by triclosan but not by penconazole or metalaxyl at concentrations up to 250 μM. The repressive effect of triclosan was dependent on culture conditions. Caulobacter crescentus was more sensitive to triclosan when grown with high glucose at high cell density than when grown directly in sterilized lake water at low cell density. This suggests that the use of conventional growth conditions may overestimate biocide toxicity. Additional experiments showed that the freshwater community was more sensitive to triclosan than C.  crescentus, with 10 nM of triclosan being sufficient to repress growth and change the phylogenetic composition of the community. These results demonstrate that isolate-based assays may underestimate biocide toxicity and highlight the importance of assessing toxicity directly on natural microbial communities. Because 10 nM of triclosan is within the range of concentrations observed in freshwater systems, these results also raise concerns about the risk of introducing triclosan into the environment.

Intracellular thiol-mediated modulation of epithelial sodium channel activity.

The epithelial sodium channel ENaC is physiologically important in the kidney for the regulation of the extracellular fluid volume, and in the lungs for the maintenance of the appropriate airway surface liquid volume that lines the pulmonary epithelium. Besides the regulation of ENaC by hormones, intracellular factors such as Na(+) ions, pH, or Ca(2+) are responsible for fast adaptive responses of ENaC activity to changes in the intracellular milieu. In this study, we show that ENaC is rapidly and reversibly inhibited by internal sulfhydryl-reactive molecules such as methanethiosulfonate derivatives of different sizes, the metal cations Cd(2+) and Zn(2+), or copper(II) phenanthroline, a mild oxidizing agent that promotes the formation of disulfide bonds. At the single channel level, these agents applied intracellularly induce the appearance of long channel closures, suggesting an effect on ENaC gating. The intracellular reducing agent dithiothreitol fully reverses the rundown of ENaC activity in inside-out patches. Our observations suggest that changes in intracellular redox potential modulate ENaC activity and may regulate ENaC-mediated Na(+) transport in epithelia. Finally, substitution experiments reveal that multiple cysteine residues in the amino and carboxyl termini of ENaC subunits are responsible for this thiol-mediated inhibition of ENaC.

Inhibition of bicarbonate transport protects embryonic heart against reoxygenation-induced dysfunction.

It has not been well established whether the mechanisms participating in pH regulation in the anoxic-reoxygenated developing myocardium resemble those operating in the adult. We have specially examined the importance of Na+/H+ exchange (NHE) and HCO3-dependent transports in cardiac activity after changes in extracellular pH (pHo). Spontaneously contracting hearts isolated from 4-day-old chick embryos were submitted to single or repeated anoxia (1 min) followed by reoxygenation (10 min). The chronotropic, dromotropic and inotropic responses of the hearts were determined in standard HCO3- buffer at pHo 7.4 and at pHo 6.5 (hypercapnic acidosis). In distinct experiments, acidotic anoxia preceded reoxygenation at pHo 7.4. NHE was blocked with amiloride derivative HMA (1 micro mol/l) and HCO3-dependent transports were inactivated by replacement of HCO3 or blockade with stilbene derivative DIDS (100 micro mol/l). Anoxia caused transient tachycardia, depressed mechanical function and induced contracture. Reoxygenation temporarily provoked cardiac arrest, atrio-ventricular (AV) block, arrhythmias and depression of contractility. Addition of DIDS or substitution of HCO3 at pHo 7.4 had the same effects as acidosis per se, i.e. shortened contractile activity and increased incidence of arrhythmias during anoxia, prolonged cardioplegia and provoked arrhythmias at reoxygenation. Under anoxia at pHo 6.5/reoxygenation at pHo 7.4, cardioplegia, AV block and arrhythmias were all markedly prolonged. Interestingly, in the latter protocol, DIDS suppressed AV block and arrhythmias during reoxygenation, whereas HMA had no effect. Thus, intracellular pH regulation in the anoxic-reoxygenated embryonic heart appears to depend predominantly on HCO3 availability and transport. Furthermore, pharmacological inhibition of anion transport can protect against reoxygenation-induced dysfunction.

Use of aggregating cell cultures for toxicological studies.

Relatively simple techniques are now available which allow the preparation of large quantities of highly reproducible aggregate cultures from fetal rat brain or liver cells, and to grow them in a chemically defined medium. Since these cultures exhibit extensive histotypic cellular reorganization and maturation, they offer unique possibilities for developmental studies. Therefore, the purpose of the present study was to investigate the usefulness of these cultures in developmental toxicology. Aggregating brain cell cultures were exposed at different developmental stages to model drugs (i.e., antimitotic, neurotoxic, and teratogenic agents) and assayed for their responsiveness by measuring a set of biochemical parameters (i.e., total protein and DNA content, cell type-specific enzyme activities) which permit a monitoring of cellular growth and maturation. It was found that each test compound elicited a distinct, dose-dependent response pattern, which may ultimately serve to screen and classify toxic drugs by using mechanistic criteria. In addition, it could be shown that aggregating liver cell cultures are capable of toxic drug activation, and that they can be used in co-culture with brain cell aggregates, providing a potential model for complementary toxicological and metabolic studies.

Innappropriate renin secretion unmasked by captopril (SQ 14 225) in hypertension of chronic renal failure

Captopril (SQ 14 225), an orally active inhibitor of angiotensin-converting enzyme, was given to 7 hypertensive patients with chronic renal failure whose plasma-creatinine ranged from 1.5--7.4 mg/dl; whose plasma-renin activity was normal; whose hypertension was not controlled by previous therapy consisting in 5 patients of three or more antihypertensive drugs; and whose blood-pressures averaged 176/111 +/- 11/3 mm Hg. Inhibition of converting enzyme by oral captopril, 200 mg twice daily, reduced blood-pressure to 156/100 +/- 9/5 mm Hg. 5 patients needed additional treatment by frusemide 40--250 mg/day orally. With this combined regimen the blood-pressure of all patients averaged 126/85 +/- 4/3 mm Hg after 8 +/- 2 weeks of captopril. The drug was well tolerated. These results suggest that inhibition of angiotensin-converting enzyme with or without sodium depletion is an efficient treatment for hypertension associated with chronic renal failure. It appears that although renin levels in patients with this condition may be "normal", they are inappropriate in relation to the subtle degree of sodium retention that occurs with this disorder.

Regulation of the vitellogenin gene B1 promoter after transfer into hepatocytes in primary cultures.

The estrogen-dependent and tissue-specific regulation of the Xenopus laevis vitellogenin gene B1 promoter has been studied by lipid-mediated DNA transfer into Xenopus hepatocytes in primary culture. Hepatocytes achieve an efficient hormonal control of this promoter through a functional interaction between the estrogen responsive elements and a promoter proximal region upstream of the TATA box, which is characterized by a high density of binding sites for the transcription factors CTF/NF-1, C/EBP and HNF3. DNA accessibility to restriction enzymes within the chromosomal copy of the vitellogenin gene B1 promoter shows that the estrogen responsive unit and the promoter proximal region are sensitive to digestion in uninduced and estrogen-induced hepatocytes but not in erythrocyte nuclei. Together, these findings support the notion that chromatin configuration as well as the interplay of promoter elements mediate proper hormone-dependent and tissue-specific expression of the B1 vitellogenin gene.