Antikinetoplastid SAR study in 3-nitroimidazopyridine series: identification of a novel non-genotoxic and potent anti-T. b. brucei hit-compound with improved pharmacokinetic properties

To study the antikinetoplastid 3-nitroimidazo[1,2-a]pyridine pharmacophore, a structure-activity relationship study was conducted through the synthesis of 26 original derivatives and their in vitro evaluation on both Leishmania spp and Trypanosoma brucei brucei. This SAR study showed that the antitrypanosomal pharmacophore was less restrictive than the antileishmanial one and highlighted positions 2, 6 and 8 of the imidazopyridine ring as key modulation points. None of the synthesized compounds allowed improvement in antileishmanial activity, compared to previous hit molecules in the series. Nevertheless, compound 8, the best antitrypanosomal molecule in this series (EC50 = 17 nM, SI = 2650 & E° = -0.6 V), was not only more active than all reference drugs and previous hit molecules in the series but also displayed improved aqueous solubility and better in vitro pharmacokinetic characteristics: good microsomal stability (T1/2 > 40 min), moderate albumin binding (77%) and moderate permeability across the blood brain barrier according to a PAMPA assay. Moreover, both micronucleus and comet assays showed that nitroaromatic molecule 8 was not genotoxic in vitro. It was evidenced that bioactivation of molecule 8 was operated by T. b. brucei type 1 nitroreductase, in the same manner as fexinidazole. Finally, a mouse pharmacokinetic study showed that 8 displayed good systemic exposure after both single and repeated oral administrations at 100 mg/kg (NOAEL) and satisfying plasmatic half-life (T1/2 = 7.7 h). Thus, molecule 8 appears as a good candidate for initiating a hit to lead drug discovery program

No evidence of oxidant events in amphotericin B cytotoxicity versus

Amphotericin B is used for the treatment of systemic mycoses and visceral leishmaniasis. The objective of our study was to evaluate the impact of catalase, ascorbic acid and ketoconazole on the amphotericin B toxicity towards Leishmania promastigotes membrane by two flow cytometric tests, the membrane potential assay using a cationic dye, [DiOC5 (3)], and the membrane permeability test using propidium iodide. The collapse of membrane potential appeared at amphotericin B concentrations weaker than those assessed by the membrane permeability test. The binding of amphotericin B to membrane sterol was not modified by catalase or ascorbic acid whereas amphotericin B-induced growth inhibition could be modulated by these products. The permeabilizing effect of amphotericin B on parasite membrane was strongly reduced in the presence of ketoconazole. These results confirmed the pore hypothesis of amphotericin B action and suggested that flow cytometric methods constituted a valuable alternative to conventional methods for assessing the effect of drugs on cellular membrane and evaluating parasite susceptibility to polyene antibiotics

Mechanics of the Toxoplasma gondii oocyst wall.

The ability of microorganisms to survive under extreme conditions is closely related to the physicochemical properties of their wall. In the ubiquitous protozoan parasite Toxoplasma gondii, the oocyst stage possesses a bilayered wall that protects the dormant but potentially infective parasites from harsh environmental conditions until their ingestion by the host. None of the common disinfectants are effective in killing the parasite because the oocyst wall acts as a primary barrier to physical and chemical attacks. Here, we address the structure and chemistry of the wall of the T. gondii oocyst by combining wall surface treatments, fluorescence imaging, EM, and measurements of its mechanical characteristics by using atomic force microscopy. Elasticity and indentation measurements indicated that the oocyst wall resembles common plastic materials, based on the Young moduli, E, evaluated by atomic force microscopy. Our study demonstrates that the inner layer is as robust as the bilayered wall itself. Besides wall mechanics, our results suggest important differences regarding the nonspecific adhesive properties of each layer. All together, these findings suggest a key biological role for the oocyst wall mechanics in maintaining the integrity of the T. gondii oocysts in the environment or after exposure to disinfectants, and therefore their potential infectivity to humans and animals

Surgical management of popliteal artery aneurysms: Which factors affect outcomes?

Objective: Popliteal artery aneurysm (PAA) is uncommon. The clinical presentation of PAA includes rupture, embolism, and thrombosis. In this article, we evaluate the results of our 20-year experience with surgical management of PAAs, analyzing the role of anatomic, clinical, and surgical factors that potentially affect early and long-term results. Methods: From January 1984 to December 2004, 159 PAAs in 137 patients were operated on at our department. Data from all the patients were retrospectively collected in a database. PAAs were asymptomatic in 67 cases (42%); 5 (3%) PAAs were ruptured. In 51 cases (32%), PAA caused intermittent claudication. The remaining 36 limbs (23%) had threatening ischemia due in 30 cases to acute PAA thrombosis, in 4 cases to chronic PAA thrombosis, and in 2 cases to distal embolization. In selected patients with acute ischemia, preoperative intra-arterial thrombolysis with urokinase was performed. Early results in terms of mortality, graft thrombosis, and limb salvage were assessed. Follow-up consisted of clinical and ultrasonographic examinations at 1, 6, and 12 months and yearly thereafter. Long-term survival, patency, and limb salvage rates were analyzed. Results: Forty cases were treated with aneurysmectomy and prosthetic graft interposition; in 39 cases, the aneurysm was opened, and a graft was placed inside the aneurysm. Four patients had aneurysmectomy with end-to-end anastomosis. In 73 cases, ligation of the aneurysm with bypass grafting (39 with a prosthetic graft and 34 with an autologous vein) was performed. The remaining three patients underwent endovascular exclusion of their PAAs. A medial approach was used in 97 patients (61%), and a posterior approach was used in 59 patients (37.1%). The outflow vessel was in most cases (93.7%) the below-knee popliteal artery. Thirty-day amputation and death rates were 4.4% (7/159 limbs) and 2.1% (3/137 patients), respectively. The amputation rate was significantly higher in symptomatic limbs than in asymptomatic ones (6.5% and 1.4%, respectively; P = .05). Eight limbs (5%) had an early graft thrombosis that required a reintervention. Follow-up was available in 116 patients (84.7%) and 138 limbs (86%) with a mean follow-up time of 40 months (range, 1-205 months). The cumulative estimated 60-month survival, limb salvage, and primary and secondary patency rates were 84.2%, 86.7%, 66.3%, and 83.6%, respectively. Asymptomatic limbs had significantly better results than symptomatic ones in terms of limb salvage (93.4% and 80.4%, respectively; P = .03; log-rank, 4.2) and primary patency (86.5% and 51.6%, respectively; P = .001; log-rank, 10.3). Among symptomatic patients, results were better in claudicant limbs than in acutely ischemic ones in terms of limb salvage (90.5% and 58.7%, respectively; P = .001; log-rank, 17.5). Univariate analysis showed the absence of symptoms, the presence of two or three tibial vessels, the use of a posterior approach, the kind of intervention, and the site of distal anastomosis to significantly affect long-term patency. Cox regression for factors affecting 60-month primary patency showed that clinical presentation, runoff status, and the site of distal anastomosis significantly influenced long-term results. Conclusions: Results of surgery on asymptomatic PAAs are good - significantly better than those for symptomatic ones. Elective surgical intervention should be performed in patients with a low surgical risk and a long life expectancy when the correct indication exists. In thrombosed aneurysms, intra-arterial thrombolysis may represent an alternative to emergent surgical management. Our data demonstrated that results are similarly good in claudicants, and this fact confirms that only acute ischemia due to PAA thrombosis represents a real surgical challenge. In selected patients with focal lesions, a posterior approach seems to offer better long-term results. The runoff status and the site of distal anastomosis affect long-term patency as well. Copyright © 2006 by The Society for Vascular Surgery

Carotid artery dissection

Carotid dissection may be spontaneous, traumatic or iatrogenic. The incidence of this disease is very low. Carotid dissection is a rare cause of ischemic stroke and the instrumental diagnosis includes conventional angiography, magnetic resonance imaging, ultrasound techniques and helical computed tomography angiography. Anticoagulant therapies are recommended for all the patients regardless by dissection's aetiology in order to prevent thromboembolic complications. Options for open surgical repair include resection of the involved segment with interposition of vein graft, thromboendarterectomy and patch closure, extracranial to intracranial carotid artery bypass, gradual dilation of the carotid artery and ligation of the cervical carotid artery. More recently endovascular techniques have been used to treat high-grade stenosis and aneurysmal dilatation as a consequence of a carotid dissection. No evidence exists about the benefits of one technique than the others. In any case, surgical or endovascular treatment should be reserved for patients who have persistent symptoms of ischemia despite adequate anticoagulation. In this report we review recent new knowledges in epidemiology and pathogenesis of carotid artery dissection, paying particular attention to clinical manifestations, methods of diagnosis and kinds of treatment

The Treatment of Isolated Iliac Artery Aneurysm in Patients with Non-aneurysmal Aorta

Objectives: The aim of the study was to evaluate early and mid-term results of surgical repair of isolated iliac artery aneurysm (IAA) in patients with non aneurysmal abdominal aorta. Methods: From January 1996 to December 2006, 34 patients with IAA had elective surgery. In 32 cases open repair was performed. Two patients had endovascular repair using a tube endoprosthesis and internal iliac artery coil embolization. The diameters of the abdominal aorta and iliac arteries were measured preoperatively and during follow-up. Early and late results in terms of mortality, major morbidity, reinterventions and graft-related complications were recorded. Mean pre and postoperative diameters of abdominal aorta were compared. Results: The site of the IAA was the common iliac artery in 29 cases (10 bilateral), internal iliac artery in 4 cases and external iliac artery in 1 case. Preoperative mean abdominal aortic diameter was 22.2 mm (SD 7.6). There were no perioperative deaths and two major complications (retroperitoneal bleeding and limb ischemia) occurred. At the median follow-up time of 24 months survival was estimated as 91%. No reinterventions, graft thrombosis and graft related complications occurred. There were no cases of abdominal aorta aneurysm development. Mean aortic diameter at the most recent imaging was 23.1 mm, which was not significantly different from preoperative values (p = 0.2). Conclusions: Surgical treatment of IAAs provides good early and mid-term results. During mid-term follow-up the diameter of abdominal aorta remains stable, suggesting IAA may be a localized aneurysmal disease. © 2007 European Society for Vascular Surgery