X-ray Reflectivity Study of the Interaction of an Imidazolium-Based Ionic Liquid with a Soft Supported Lipid Membrane.

Ionic liquids (ILs) are important for their antimicrobial activity and are found to be toxic to some microorganisms. To shed light on the mechanism of their activities, the interaction of an imidazolium-based IL 1-butyl-3-methylimidazolium tetrfluoroborate ([BMIM][BF4]) with E. coli bacteria and cell-membrane-mimicking lipid mono- and bilayers has been studied. The survival of the bacteria and corresponding growth inhibition are observed to be functions of the concentration of the IL. The IL alters the pressure-area isotherm of the monolayer formed at an air-water interface by the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid. The in-plane elasticity of the lipid layer is reduced as a consequence of the insertion of this IL. The X-ray reflectivity study from a polymer-supported lipid bilayer shows strong perturbation in the self-assembled structure of the bilayer due to the interaction. As a consequence, there is a considerable decrease in bilayer thickness and a corresponding increase in electron density. These results, however, depend on the chain configurations of the lipid molecules.

Percutaneous transvenous mitral commissurotomy for rheumatic mitral stenosis with impaired left ventricular function: an echocardiographic follow-up study.

Sixty consecutive patients of rheumatic mitral stenosis who underwent percutaneous transvenous mitral commissurotomy were evaluated and followed up for 3 months in order to study the effect of the procedure on left ventricular ejection fraction and to elucidate the pathophysiology of impaired left ventricular function. The response in 16 patients (26.7%) with left ventricular dysfunction (ejection fraction less than 50%) was compared to that in 44 patients with normal left ventricular ejection fraction. Patients with left ventricular dysfunction had relatively larger left ventricular end-diastolic (84 +/- 15 vs. 76 +/- 14 ml) and end-systolic (45 +/- 11.5 vs. 35 +/- 12 ml) volumes. Percutaneous transvenous mitral commissurotomy was successful in all patients. Mitral valve area increased in all patients, from 0.8 +/- 0.2 cm2 to 1.82 +/- 0.37 cm2. After commissurotomy there was a trend towards increase of the left ventricle end-diastolic volumes in both groups of patients. Left ventricular ejection fraction also marginally increased in both groups. A reduced left ventricular compliance due to thickened and fibrotic mitral valve apparatus and excessive afterload due to increased systemic vascular resistance because of low output are possible mechanisms for left ventricular dysfunction in patients with mitral stenosis.