In Vitro Inhibitory Effect of SR 27417, a Potent Platelet-Activating Factor (PAF) Receptor Antagonist, on the PAF-Induced Bovine Platelet Aggregation

The in vitro inhibitory effect of SR 27417, an antagonist of the platelet-activating factor (PAF) receptor, on PAF-induced platelet aggregation was studied in blood collected from seven healthy Friesien calves. Inhibitory effects of SR 27417 were determined at thirteen different concentrations (0.1-400 nM) by using the dose-response curves of PAF on calf platelet aggregation. In the presence of SR 27417, the maximal slopes of aggregation (%/min) induced by low and high concentrations of PAF were significantly different from the control values obtained without an antagonist at p < or = 0.05 and p < or = 0.01 respectively. In vitro PAF-induced calf platelet aggregation was dose-dependently inhibited by SR 27417. The drug inhibited PAF-induced platelet aggregation in a competitive reversible manner (pA2 = 10.46 +/- 2.36 mol x L(-1)). In conclusion, the results of our study showed that addition of SR 27417 to bovine platelet in vitro inhibits PAF-induced platelet aggregation.Effet inhibiteur in vitro du SR 27417, un puissant antagoniste du récepteur du facteur d'activation plaquettaire sur l'agrégation des plaquettes induite par le PAF chez le bovin. L'effet inhibiteur in vitro du SR 27417, un antagoniste du récepteur du facteur d'activation plaquettaire (PAF) induite par le PAF sur l'agrégation plaquettaire a été étudiée dans le sang prélevé des sept veaux sains de race Frisonne. L'effet inhibiteur du SR 27417 a été déterminé avec treize concentrations différentes (0,1 - 400 nM) en utilisant les courbes dose-effet du PAF sur l'agrégation plaquettaire des veaux. En présence du SR 27417, la pente d'agrégation maximale de la courbe ( concentrations du PAF ont été significativement différentes des valeurs de base ( et respectivement). L'agrégation des plaquettes induites par le PAF a été inhibée in vitro par le SR 27417 d'une manière dépendante de la dose. Le médicament a inhibé in vitro l'agrégation induite par le PAF des plaquettes chez le bovin de façon compétitive et réversible (pA2 = 10.46 2.36 molL-1). En conclusion, les résultats de notre étude montrent in vitro que l'addition du SR 27417 aux plaquettes chez le bovin inhibe l'agrégation plaquettaire induite par le PAF.Peer reviewe

A data-driven modeling method to analyze cardiomyocyte impedance data

Présentation PosterInternational audienceOne goal of the Comprehensive in vitro ProArrhythmia Assay initiative is to predict more accurately potentially torsadogenic compounds in an earlier stage of drug development. To that aim one of the CiPA component is to assess capabilities of label-free in vitro assays (impedance and extracellular field potential signals) applied to human stem cell-derived cardiomyocytes

A novel statistical signal processing method to estimate effects of compounds on contractility of cardiomyocytes using impedance assays

International audienceLabel free methods such as cell impedance assays are in vitro tests increasingly used in drug development and producing large and high-content data files. Since the current commercial software are not suited for fully automated analysis , there is a need to develop validated and rapid solutions to extract relevant information for biologists. This need is particularly obvious in the case of impedance signals analysis from cardiomyocytes. The proposed solution is based on three main steps. The first one consists in calculating five indices informing about the time variations of frequency (F), amplitude (A), shape (S) of beatings, trends (T) of the cardiomyocyte dependent on spreading, viability and attachment as well as irregularity (I) of the contractility. In a second phase, two summary statistics are proposed to test the concentration effect of drugs on the five FASTI indices. Results of the statistical tests are finally aggregated in a cardio-effect grade to compare the tested molecules in a cardio-impact scale graduated from 0 (no influence) to 10 (highly disturbed effects in cardiomy-ocytes). This innovative approach was tested using in vitro data obtained from cell impedance analysis of three known molecules (2 cardiotoxic and 1 non-cardiotoxic compounds). Results have clearly shown the ability of the proposed approach to identify significant effects on the contractility of cardiomyocytes. This solution speeds up the analysis of cardiomyocyte impedance data, takes into account all the kinetic data generated and is now available for biologists on a web-platform: i-Cardio TM developed by CYBERnano TM

Investigative safety strategies to improve success in drug development

Understanding and reducing attrition rate remains a key challenge in drug development. Preclinical and clinical safety issues still represent about 40% of drug discontinuation, of which cardiac and liver toxicities are the leading reasons. Reducing attrition rate can be achieved by various means, starting with a comprehensive evaluation of the potential safety issues associated to the primary target followed by an evaluation of undesirable secondary targets. To address these risks, a risk mitigation plan should be built at very early development stages, using a panel of in silico, in vitro, and in vivo models. While most pharmaceutical companies have developed robust safety strategies to de-risk genotoxicity and cardiotoxicity issues, partly driven by regulatory requirements; safety issues affecting other organs or systems, such as the central nervous system, liver, kidney, or gastro-intestinal system are less commonly addressed during early drug development. This paper proposes some de-risking strategies that can be applied to these target organ systems, including the use of novel biomarkers that can be easily integrated in both preclinical and clinical studies. Experiments to understand the mechanisms’ underlying toxicity are also important. Two examples are provided to demonstrate how such mechanistic studies can impact drug development. Novel trends in investigative safety are reviewed, such as computational modeling, mitochondrial toxicity assessment, and imaging technologies. Ultimately, understanding the predictive value of non-clinical safety testing and its translatability to humans will enable to optimize assays in order to address the key objectives of the drug discovery process, i.e., hazard identification, risk assessment, and mitigation

Avantages des nouveaux traitements contre les puces et les tiques

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Endogenous nitric oxide modulates acetylcholine-induced edema and vasoconstriction in isolated perfused rabbit lungs.

The modulatory role of endogenous nitric oxide (NO) on pulmonary edema induced by acetylcholine (ACh), capsaicin, substance P (SP) and 5-hydroxytryptamine (5-HT) was investigated by using an inhibitor of NO synthase, N-omega-nitro-L-arginine (L-NNA). The effects of endogenous NO on the hemodynamic response to ACh, 5-HT and SP were also investigated. The capillary filtration coefficient (Kf,c), the total pressure gradient (delta Pt) and its four components [arterial (delta Pa), pre- (delta Pa') and post-capillary (delta Pv'), and venous gradient (delta Pv)] were evaluated on isolated, ventilated, perfused rabbit lungs. ACh (10(-8) to 10(-4) M) and SP (10(-10) to 10(-6) M) induced a concentration-dependent increase in the Kf,c. Capsaicin (10(-4) M) and 5-HT (10(-4) M) also increased this parameter. L-NNA (10(-4) M) completely inhibited the effects of ACh and capsaicin on the Kf,c, without preventing the effects of SP and 5-HT. ACh induced a concentration-dependent vasoconstriction in the precapillary segment. Pretreatment with L-NNA enhanced this increase in delta Pa' but also increased delta Pv' and delta Pv. 5-HT increased delta Pt and delta Pa proportionally to the concentration. This effect was enhanced by L-NNA, which also increased delta Pa'. SP had no significant hemodynamic effect. Pretreatment with L-NNA did not modify the response to SP. Sodium nitroprusside (10(-5) M) induced a left shift of the concentration-response curve to ACh on the Kf,c, although it did not change the response to SP. Sodium nitroprusside also inhibited the hemodynamic effect of ACh. It was concluded that endogenous NO is involved in ACh-and capsaicin-induced edema via a prejunctional stimulatory effect on the C-fibers. Endogenous NO can also modulate ACh- and 5-HT-induced vasoconstriction by exerting a vasodilator action on the whole pulmonary vascular bed

Role of Neuropeptides in Acetylcholine-Induced Edema in Isolated and Perfused Rabbit Lungs

Changes in pulmonary endothelial permeability and in microvascular hemodynamics in response to cumulative concentrations of acetylcholine (ACh) (10(-8) M to 10(-5) M) were investigated in isolated, perfused rabbit lungs. The total pressure gradient was partitioned into four components: arterial, pre- and postcapillary and venous. The capillary filtration coefficient (Kf, c) also was evaluated. ACh caused a significant increase in arterial and precapillary pressures at concentrations higher than 3 x 10(-6) M. The total pressure gradient and precapillary were significantly increased whereas arterial, postcapillary and venous pressure gradient remained unchanged. In papaverine (3 x 10(-4) M)-pretreated lungs, the vasoconstriction was abolished and a concentration-dependent increase in Kf,c was recorded from 10(-8) to 10(-5) M ACh. This reaction was accompanied by pulmonary edema. Atropine, indomethacin, aspirin, ketanserin, clonidine, morphine and (+/-)-CP 96-345, an antagonist of neurokinin NK1 receptors, completely prevented the effects of ACh on Kf,c. In contrast, cromolyn sodium and SR48968, a neurokinin NK2 antagonist, did not inhibit the response to ACh. Terfenadine together with cimetidine had a partially inhibitory effect. Changes in the Kf, c similar to those observed with ACh were induced by capsaicin (10(-4) M) by exogenous substance P (10(-7) M) and by 5-hydroxytryptamine (5-HT) (10(-4) M). The effects of SP were inhibited by aspirin, (+/-)-CP 96,345 and ketanserin, but not by atropine and antihistaminics. 5-HT effects were prevented by aspirin and not by (+/-)-CP 96,345. It was concluded that ACh-induced pulmonary edema was due to an increase in the capillary filtration coefficient.(ABSTRACT TRUNCATED AT 250 WORDS

Toxicité des herbicides chez les animaux domestiques

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