Biomedical subjects

Julien Hanson

Publications and source records attributed to Julien Hanson.

8 recordsLinked to original sources

PubMed2005

Effects of dobutamine on left ventriculoarterial coupling and mechanical efficiency in acutely ischemic pigs.

This study investigated the effects of dobutamine on left ventriculoarterial (VA) coupling and mechanical efficiency in acutely ischemic pigs. Experiments were performed in 12 pigs in which vascular properties, including peripheral resistance (R2), compliance (C), and arterial elastance (Ea), were estimated with a windkessel model, and left ventricular (LV) function by the slope (Ees) of the end-systolic pressure-volume relationship (ESPVR) and stroke work (SW). VA coupling was defined as Ees/Ea, and mechanical efficiency as SW/pressure-volume area (PVA). In all animals, the left anterior descending coronary artery was ligated after basal measures. The animals were then randomly divided into 2 groups: group CTRL (n = 6) was followed for 180 minutes without other intervention, whereas group DOBU (n = 6) was infused with dobutamine (5 microg x kg(-1) x min(-1)) starting after T60 measures. Coronary occlusion induced a rightward shift of ESPVR and a decrease in Ees from 3.67 +/- 0.33 to 1.92 +/- 0.20 mm Hg x mL(-1), while Ea changed from 3.33 +/- 0.56 to 4.65 +/- 0.29 mm Hg x mL, R2 from 1.72 +/- 0.30 to 2.38 +/- 0.16 mm Hg x s x mL(-1), and C from 0.78 +/- 0.16 to 0.46 +/- 0.08 mL x mm Hg(-1). This altered VA coupling from 1.22 +/- 0.11 to 0.44 +/- 0.07. SW decreased from 4056 +/- 223 to 2372 +/- 122 mm Hg x mL, and PVA and SW/PVA decreased from 5575 +/- 514 to 4830 +/- 317 mm Hg x mL, and from 0.76 +/- 0.04 to 0.49 +/- 0.03, respectively. In group DOBU, dobutamine restored Ees and the position of ESPVR to baseline values, while Ea decreased to 3.39 +/- 0.34 mm Hg x mL(-1) because of an R2 decrease to 1.60 +/- 0.24 mm Hg x s x mL(-1). VA coupling was restored. SW and PVA increased to 3833 +/- 180 mm Hg x mL and to 7498 +/- 442 mm Hg x mL, respectively, while SW/PVA was unchanged. In ischemic pigs, dobutamine restored VA coupling through an increase in LV contractility and decrease in arterial elastance as a result of peripheral vasodilatation. However, myocardial oxygen consumption was increased, and mechanical efficiency impaired.

Algorithms↗

PubMed2004

In vitro and in vivo pharmacological characterization of BM-613 [N-n-pentyl-N'-[2-(4'-methylphenylamino)-5-nitrobenzenesulfonyl]urea], a novel dual thromboxane synthase inhibitor and thromboxane receptor antagonist.

Thromboxane A2 (TXA2) is a key mediator of platelet aggregation and smooth muscle contraction. Its action is mediated by its G protein-coupled receptor of which two isoforms, termed TPalpha and TPbeta, occur in humans. TXA2 has been implicated in pathologies such as cardiovascular diseases, pulmonary embolism, atherosclerosis, and asthma. This study describes the pharmacological characterization of BM-613 [N-n-pentyl-N'-[2-(4'-methylphenylamino)-5-nitrobenzenesulfonyl]urea], a new combined TXA2 receptor antagonist and TXA2 synthase inhibitor. It exhibits a strong affinity for human platelet TP receptors (IC50 = 1.4 nM), TPalpha and TPbeta expressed in COS-7 cells (IC(50) = 2.1 and 3.1 nM, respectively), and TPs expressed in human coronary artery smooth muscle cells (IC50 = 29 microM). BM-613 shows a weak ability to prevent contraction of isolated rat aorta (ED50 = 1.52 microM) and guinea pig trachea (ED50 = 2.5 microM) induced by TXA2 agonist U-46619 (9.11-dideoxy-9.11-methanoepoxy-prostaglandin F2). Besides, BM-613 antagonizes TPalpha (IC50 = 0.11 microM) and TPbeta (IC50 = 0.17 microM) calcium mobilization induced by U-46619 and inhibits human platelet aggregation induced by U-46619 (ED50 = 0.278 microM), arachidonic acid (ED50 = 0.375 microM), and the second wave of ADP. BM-613 also dose dependently prevents TXA2 production by human platelets (IC50 = 0.15 microM). In a rat model of ferric chloride-induced thrombosis, BM-613 significantly reduces weight of formed thrombus by 79, 49, and 28% at 5, 2, and 1 mg/kg i.v., respectively. In conclusion, BM-613 is a dual and potent TP receptor antagonist and TXA2 synthase inhibitor characterized by a strong antiplatelet and antithrombotic potency. These results suggest that BM-613 could be a potential therapeutic drug for thrombotic disorders.

Aniline Compounds↗

PubMed2004

Effect of BM-573 [N-terbutyl-N'-[2-(4'-methylphenylamino)-5-nitro-benzenesulfonyl]urea], a dual thromboxane synthase inhibitor and thromboxane receptor antagonist, in a porcine model of acute pulmonary embolism.

The aim of this study was to evaluate the effect of BM-573 [N-terbutyl-N'-[2-(4'-methylphenylamino)-5-nitro-benzenesulfonyl]urea], a dual thromboxane A2 synthase inhibitor and receptor antagonist, on the hemodynamic response to acute pulmonary embolism. Six anesthetized pigs were infused with placebo (placebo group) and compared with six other pigs receiving a continuous infusion of BM-573 (BM group). Pulmonary embolization with 0.3 g/kg autologous blood clots was carried out 30 min after the start of the infusion. Right ventricular pressure-volume loops were recorded using a conductance catheter, and end-systolic ventricular elastance was periodically assessed by varying right ventricular preload. Pulmonary vascular properties were studied by use of a four-element windkessel model. Hemodynamic data, including assessment of right ventricular-arterial coupling, were collected at baseline and every 30 min for 4 h. Blood samples were collected to assess gas exchange, thromboxane A2, and prostacyclin plasma levels and to evaluate platelet aggregation. Mean pulmonary arterial pressure in the placebo group increased significantly more than in the BM group, mainly because of an additional increase in pulmonary vascular resistance. Arterial and end-systolic ventricular elastances increased also more in the placebo group, whereas right ventricular efficiency decreased. BM-573 prevented both platelet aggregation induced by U-46619 (9,11-dideoxy-11alpha,9alpha-epoxymethanoprostaglandin F2alpha) or by arachidonic acid, and thromboxane A2 overproduction, whereas prostacyclin liberation was preserved. Oxygenation, however, was not significantly improved. We conclude that in this animal model of acute pulmonary embolism, infusion of BM-573 reduced pulmonary vasoconstriction. As a result, right ventricular-vascular coupling values were maintained at a maximal efficiency level.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed2004

Pharmacological characterization of N-tert-butyl-N'-[2-(4'-methylphenylamino)-5-nitrobenzenesulfonyl]urea (BM-573), a novel thromboxane A2 receptor antagonist and thromboxane synthase inhibitor in a rat model of arterial thrombosis and its effects on bleeding time.

The present study was undertaken to characterize the antiplatelet and antithrombotic effects of BM-573 [N-tert-butyl-N'-[2-(4'-methylphenylamino)-5-nitrobenzenesulfonyl]urea], an original combined thromboxane receptor antagonist and thromboxane synthase inhibitor in rats, and to determine its effects on mice bleeding time. Intraperitoneal injection of a single dose of 5 mg/kg BM-573 to rats inhibited U-46619 (9,11-dideoxy-9,11-methanoepoxy-prostaglandin F(2))-induced washed platelet aggregation 30 min and 1, 2, and 4 h after drug administration with a maximum antiplatelet effect observed after 1 and 2 h. In a rat model of thrombosis induced by ferric chloride application on the abdominal aorta, BM-573 significantly reduced the thrombus weight by 92.53, 80.20, 64.75, and 18.21% at doses of 5, 2, 0.5, and 0.2 mg/kg, respectively. Time to occlusion of abdominal aorta in the BM-573-treated group (41.50 +/- 5.21 min) was significantly prolonged compared with the vehicle-treated rats (16.16 +/- 0.79 min). Like furegrelate, seratrodast, and acetylsalicylic acid, BM-573 did not affect the tail bleeding time induced by tail transection in mice compared with vehicle-treated mice. Moreover, BM-573, a close derivative of the loop diuretic torasemide, failed to induce a significant increase in diuresis in rat and did not produce a decrease in blood glucose concentration as observed with the sulfonylurea glibenclamide. In conclusion, we have demonstrated that the nitrobenzenic sulfonylurea BM-573, an original combined thromboxane receptor antagonist and thromboxane synthase inhibitor, is a potent antithrombotic agent that does not affect bleeding time. Moreover, BM-573 lost the diuretic property of torasemide and has no impact on glycemia.

Animals↗

PubMed2004

New developments on thromboxane and prostacyclin modulators part I: thromboxane modulators.

The pathogenesis of numerous cardiovascular, pulmonary, inflammatory, and thromboembolic diseases can be related to arachidonic acid (AA) metabolites. One of these bioactive metabolites of particular importance is thromboxane A(2) (TXA(2)). It is produced by the action of thromboxane synthase on the prostaglandin endoperoxide H(2)(PGH(2)), which results from the enzymatic degradation of AA by the cyclooxygenases. TXA(2) is a potent inducer of platelet aggregation, vasoconstriction and bronchoconstriction. It is involved in a series of major pathophysiological states such as asthma, myocardial ischemia, pulmonary hypertension, and thromboembolic disorders. Therefore, TXA(2) receptor antagonists, thromboxane synthase inhibitors and drugs combining both properties have been developed by several pharmaceutical companies since the early 1980s. Several compounds have been launched on the market and others are under clinical evaluation. Moreover, the recent literature reported the interest of thromboxane modulators, which combine another pharmacological activity such as, platelet activating factor antagonism, angiotensin II antagonism, or 5-lipoxygenase inhibition. In this review, we will propose a description of the recently described thromboxane modulators of major interest from both a pharmacological and a chemical point of view.

Arachidonic Acid↗

PubMed2004

New developments on thromboxane and prostacyclin modulators part II: prostacyclin modulators.

Prostacyclin (PGI(2)) is a potent endogenous inhibitor of platelet function and possesses a strong vasodilator effect. Furthermore, prostacyclin is currently presented as the physiologic antagonist of thromboxane A(2)(TXA(2)), which exhibits pro-aggregatory and vasoconstrictor properties. So, the balance between PGI(2) and TXA(2) production is crucial for the cardiovascular system. Indeed, an imbalance in the production or effect of these products is deleterious for the circulatory system and can lead to characterized vascular diseases such as hypertension, stroke, atherosclerosis or myocardial infarction. Although the biological effects of PGI(2) are considered to be clinically useful, its use as therapeutic agent is largely limited by both its chemical and metabolic instability. Actually, several prostacyclin agonists have been synthesized and pharmacologically evaluated. Among these, some have been clinically evaluated as therapeutic agents in several vascular diseases. This review focuses on the latest chemical and pharmacological developments in the field of the prostacyclin agonists.

Cardiovascular System↗

PubMed2004

New developments on thromboxane modulators.

Thromboxane A(2) (TXA(2)) is a labile product formed from arachidonic acid by cyclooxygenase. The pathogenesis of numerous cardiovascular, pulmonary, and thromboembolic diseases can be related to this metabolite. Therefore, TXA(2) modulators have been developed for 20 years. This review will highlight the evolution in the field of TXA(2) modulators.

Enzyme Inhibitors↗

PubMed2004

Progress in the field of GPIIb/IIIa antagonists.

Platelet aggregation plays an important role in pathological situations such as myocardial infarction, unstable angina, peripheral artery disease, and stroke. Thus, pharmacological agents that specifically inhibit platelet aggregation are of great interest in the treatment and prevention of these cardiovascular diseases. Since binding of activated glycoprotein IIb/IIIa complex, a platelet surface integrin, to fibrinogen is the final step leading to platelet aggregation regardless of the initial stimulus, many researches have focused on the development of drugs that could antagonize this integrin. Three intravenous glycoprotein IIb/IIIa antagonists are currently marketed for the prevention of myocardial infarction in patients undergoing percutaneous intervention: Abciximab, Eptifibatide and Tirofiban. To further test the clinical efficacy of these agents, oral glycoprotein IIb/IIIa antagonists have been developed but only led to disappointing clinical results. Nevertheless, due to recognized usefulness of oral agents for the prevention and treatment of cardiovascular diseases, a great number of new orally active compounds are under clinical or preclinical evaluation. The aim of this review is to describe the chemical, pharmacological and clinical properties of existing and forthcoming glycoprotein IIb/IIIa antagonists.

Administration, Oral↗