Search results for "LMI"
showing 10 items of 1764 documents
Stability of Asymmetric Lipid Bilayers Assessed by Molecular Dynamics Simulations
2009
The asymmetric insertion of amphiphiles into biological membranes compromises the balance between the inner and outer monolayers. As a result, area expansion of the receiving leaflet and curvature strain may lead to membrane permeation, shape changes, or membrane fusion events. We have conducted both atomistic and coarse-grained molecular dynamics simulations of dipalmitoyl-phosphatidylcholine (DPPC) bilayers to study the effect of an asymmetric distribution of lipids between the two monolayers on membrane stability. Highly asymmetric lipid bilayers were found to be surprisingly stable within the submicrosecond time span of the simulations. Even the limiting case of a monolayer immersed in …
AFM study of interaction forces in supported planar DPPC bilayers in the presence of general anesthetic halothane
2006
International audience; In spite of numerous investigations, the molecular mechanism of general anesthetics action is still not well understood. It has been shown that the anesthetic potency is related to the ability of an anesthetic to partition into the membrane. We have investigated changes in structure, dynamics and forces of interaction in supported dipalmitoylphosphatidylcholine (DPPC) bilayers in the presence of the general anesthetic halothane. In the present study, we measured the forces of interaction between the probe and the bilayer using an atomic force microscope. The changes in force curves as a function of anesthetic incorporation were analyzed. Force measurements were in go…
Direct Observation of Nanometer-Scale Pores of Melittin in Supported Lipid Monolayers
2015
Melittin is the most studied membrane-active peptide and archetype within a large and diverse group of pore formers. However, the molecular characteristics of melittin pores remain largely unknown. Herein, we show by atomic force microscopy (AFM) that lipid monolayers in the presence of melittin are decorated with numerous regularly shaped circular pores that can be distinguished from nonspecific monolayer defects. The specificity of these pores is reinforced through a statistical evaluation of depressions found in Langmuir-Blodgett monolayers in the presence and absence of melittin, which eventually allows characterization of the melittin-induced pores at a quantitative low-resolution leve…
Parvovirus capsid disorders cholesterol-rich membranes.
2008
In this study canine parvovirus, CPV, was found to induce disorder in DPPC:cholesterol membranes in acidic conditions. This acidicity-induced fluidizing effect is suggested to originate from the N-terminus of the viral capsid protein VP1. In accordance with the model membrane studies, a fluidizing effect was seen also in the endosomal membranes during CPV infection implying an important functional role of the fluidization in the endocytic entry of the virus.
Partition of Indicaxanthin in Membrane Biomimetic Systems. A Kinetic and Modeling Approach
2009
The solubilization site of indicaxanthin (Ind) in lipid bilayers was investigated by the kinetics of Ind oxidation by peroxyl radicals in water and in aqueous/L-alpha-dipalmitoyl-phosphatidylcholine (DPPC) vesicles, pH 7.4, and 37.0 and 48.0 degrees C, that is, in a gel-like and a crystal liquidlike bilayer state, respectively. The time-dependent Ind absorbance decay, matched with a successful simulation of the reaction kinetic mechanism by Gepasi software, supported a multistep pathway. Computer-assisted analysis allowed calculation of the rate constants associated with the reactions involved, the values of which decreased with increasing DPPC concentration. The binding constant calculated…
The influence of tin compounds on the dynamic properties of liposome membranes: A study using the ESR method
2005
AbstractThe influence of organic and inorganic compounds of tin on the dynamic properties of liposome membranes obtained in the process of dipalmitoylphosphatidylcholine (DPPC) sonication in distilled water was investigated. This was carried out by means of the spin ESR probe method. The probes were selected in such a way as to penetrate different areas of the membrane (a TEMPO probe, 5-DOXYL stearic acid, 16-DOXYL stearic acid). Four compounds of tin were chosen: three organic ones, (CH3)4Sn, (C2H5)4Sn and (C3H7)3SnCl, and one inorganic one, SnCl2. The investigated compounds were added to a liposome dispersion, which was prepared prior to that. The concentration of the admixture was change…
Modeling mass transfer in fracture flows with the time domain-random walk method
2019
The time domain-random walk method was developed further for simulating mass transfer in fracture flows together with matrix diffusion in surrounding porous media. Specifically, a time domain-random walk scheme was developed for numerically approximating solutions of the advection-diffusion equation when the diffusion coefficient exhibits significant spatial variation or even discontinuities. The proposed scheme relies on second-order accurate, central-difference approximations of the advective and diffusive fluxes. The scheme was verified by comparing simulated results against analytical solutions in flow configurations involving a rectangular channel connected on one side with a porous ma…
Ajatuksella ja ahkeruudella kolmen suvun vaiheista neljältä vuosisadalta
2018
Kirja-arvio teoksesta Immonen, Perttu: Suomen rahvaan historia. Kolmen suvun elämää keskiajalta 1800-luvulle. Atena Kustannus Oy, 2017. 639 sivua. ISBN 978- 952-300-335-4. Perttu Immonen yhdistää teoksessaan mielenkiintoisesti ja elävästi mikro- ja makrohistorian varhaismodernin ajan Suomessa. Hän seuraa kronologisesti kolmen eri seutukunnan: LänsiSuomen Sastamalan, Itä-Suomen Rantasalmen ja Pohjanmaan Kokkolan tapahtumia. Poikkeuksellisen ankarien aikojen kuvauksesta muodostuu moniulotteinen ja alueiden erilaisia kohtaloita tarkasteleva analyysi. nonPeerReviewed
Vidzemes guberņas pagasttiesas 19.gadsimtā: Valmieras apriņķa pagasttiesas iecirkņu piemērs
2016
Bakalaura darba nosaukums “Vidzemes guberņas pagasttiesas 19. gadsimtā: Valmieras apriņķa pagasttiesas iecirkņu piemērs”. Darbā pētītas Vidzemes guberņas latviešu daļas pagasttiesu funkcijas, pakļautība un to nozīme zemnieku tiesību aizstāvībā un tiesiskās izpratnes veidošanā. Darba gaitā tika secināts, ka 19. gs. gaitā pagasttiesas bija izgājušas zināmu attīstības procesu no sākotnējā, kad to funkcijās bija vērojama būtiska muižas ietekme, līdz laikam, kad tās kļuva par pilntiesīgu tiesu iestādi, kurā zemnieki varēja vērsties pēc tiesiskās aizsardzības. Pagasttiesas ļāva latviešu zemniekiem iegūt pieredzi saskarsmē ar tiesu un citām valsts institūcijām un, radot izpratni par pienākumiem un…
Valmistalon evoluutio suomalaisen puutaloteollisuuden mainoskuvastoissa 1980-2000-luvuilla
2013
Tutkielman aiheena on suomalaisten puurakenteisten valmistalojen arkkitehtuuri ja kehitys 1980-luvulta 2000-luvulle. Koska aihetta ei ole tutkittu, tutkielman tavoitteena on saada ilmiöstä kokonaiskuva. Valmistalot ovat näkyvä osa suomalaista rakennettua ympäristöä, sillä teollisesti tuotetuista omakotitaloista tuli tutkittavana ajanjaksona suosituin omakotirakentamisen muoto. Tutkimusaineistoon kuuluu 45 talokuvastoa puutaloteollisuuden eri toimijoilta sekä kolme toimitettua talo-opasta. Tutkielma edustaa laadullista tutkimusta ja pyrkii ilmiön kokonaisvaltaiseen ymmärtämiseen. Analyysi tähtää valmistalojen julkisivuarkkitehtuurin piirteiden tunnistavaan ja nimeävään tarkasteluun sekä vaik…