Vesicles dynamics

Shisheva A. Regulating Glut4 vesicle dynamics by phosphoinositide kinases and phosphoinositide phosphatases. Front Biosci. 2003 8 s945-946. 

Tsuboi, T., da Silva Xavier, G., Leclerc, I., and Rutter, G. A. 2003. 5 -AMP-activated protein kinase controls insulin-containing secretory vesicle dynamics. J Biol Chem 278 52042-5205E... 

Fluorescent styryl dyes such as FMl-43 have been used to approximate neurotransmitter release by measuring rates of ex-ocytosis (16, 72, 73). These dyes reversibly label endosomal membranes and can be taken up into intracellular synaptic vesicles during endocytosis in systems in which vesicle recycling takes place. Typically, tissue is incubated in the fluorescent dye and then stimulated to promote vesicle cycling and therefore uptake of the dye. The preparation then is washed in fresh buffer to remove dye that remained extracellular. Using fluorescent microscopy, vesicle dynamics can be tracked. Neurotransmitter release is estimated from the rate of destaining (because of exocytosis) usually during stimulation. 

The issues addressed in this chapter demonstrate that cell-sized giant vesicles provide a very useful model for resolving various effects of electric fields on lipid membranes because vesicle dynamics can be directly observed with optical... 

Kantsler, V., Segre, E., and Steinberg, V. (2007) Vesicle dynamics in time-dependent elongation flow wrinkling instability. Physical Review Letters, 99 (17), 178102. 

The study of vesicle dynamics is now a mature area of research. The main processes involved in bilayer mobility and solute transport are quite well vmderstood, but this is not so with the spontaneous formation and breakdown of vesicles. There is a significant difference between the d5mamics of micelle forma-tion/breakdown and vesicle formation/breakdown. Micelle phenomena occur on a very short time scale, with processes for most micellar systems taking place in time scales less than 1 sec. For vesicles of synthetic surfactants like the alkylbenzene-sulfonates, the relevant processes are in the second to minute time range, although surfactant monomer exchange between vesicles and aqueous solution may well take place in the mil-... 

Shear flow is characterized (in the absence of vesicles or cells) by the flow field V = jyCx, where Cx is a unit vector, compare Sect. 10.4. The control parameter of shear flow is the shear rate f, which has the dimension of an inverse time. Thus, a dimensionless, scaled shear rate y = ft can be defined, where T is a characteristic relaxation time of a vesicle. Here, t = rjoRpkBT is used, where rjo is the solvent viscosity, Rq the average radius [206]. For < 1, the internal vesicle dynamics is... 

One of the difficulties in theoretical studies of the hydrodynamic effects on vesicle dynamics is the no-slip boundary condition for the embedding fluid on the vesicle surface, which changes its shape dynamically under the effect of flow and curvature forces. In early studies, a fluid vesicle was therefore modeled as an ellipsoid with fixed shape [194]. This simplified model is still very useful as a reference for the interpretation of simulation results. 

A number of studies have focused on D-A systems in which D and A are either embedded in a rigid matrix [103-110] or separated by a rigid spacer with covalent bonds [111-118], Miller etal. [114, 115] gave the first experimental evidence for the bell-shape energy gap dependence in charge shift type ET reactions [114,115], Many studies have been reported on the photoinduced ET across the interfaces of some organized assemblies such as surfactant micelles [4] and vesicles [5], wherein some particular D and A species are expected to be separated by a phase boundary. However, owing to the dynamic nature of such interfacial systems, D and A are not always statically fixed at specific locations. 

The formation of ordered two- and three-dimensional microstructuies in dispersions and in liquid systems has an influence on a broad range of products and processes. For example, microcapsules, vesicles, and liposomes can be used for controlled drug dehvery, for the contaimnent of inks and adhesives, and for the isolation of toxic wastes. In addition, surfactants continue to be important for enhanced oil recovery, ore beneficiation, and lubrication. Ceramic processing and sol-gel techniques for the fabrication of amorphous or ordered materials with special properties involve a rich variety of colloidal phenomena, ranging from the production of monodispersed particles with controlled surface chemistry to the thermodynamics and dynamics of formation of aggregates and microciystallites. 

An alternative approach is the use of pH-sensitive fluorophores (Lichtenberg and Barenholz, lOSS). These probes are located at the lipid-water interface and their fluorescence behavior reflects the local surface pH, which is a function of the surface potential at the interface. This indirect approach allows the use of vesicles independent of their particle size. Recently, techniques to measure the C potential of Liposome dispersions on the basis of dynamic light scattering became commercially available (Muller et al., 1986). 

Scattering experiments can be performed to help determine the size and shape of the vesicles without the need for the extensive sample preparation required for electron microscopy and AFM. Dynamic (DLS) and static light scattering (SLS) are widely used to determine the size and possible shape of vesicle systems [40,42,48,49,51,... 

FIG. 1 Geometries of electrolyte interfaces, (a) A planar electrode immersed in a solution with ions, and with the ion distrihution in the double layer, (b) Particles with permanent charges or adsorbed surface charges, (c) A porous electrode or membrane with internal structures, (d) A polyelectrolyte with flexible and dynamic structure in solution, (e) Organized amphophilic molecules, e.g., Langmuir-Blodgett film and microemulsion, (f) Organized polyelectrolytes with internal structures, e.g., membranes and vesicles. 

Vesicles [10, 11] these aggregates of insoluble natural or artificial amphiphiles in water can have various shapes (spherical, cylindrical). Depending on the preparation conditions, small unilamellar or large multilamellar vesicles can be produced. The structures meet the self-organization criterion, because they are, albeit on a long time scale, dynamic and not in thermodynamic equilibrium, which would in many cases be a macroscopically phase separated lamellar phase. 

Although the drug delivery to the lipid bilayer membrane is just the first step for bioactivities and phopholipid vesicles are rather simple in view of the composite structure of biomembranes, the unambiguous specification of the preferential location of the drug is essential the successive processes of the action are expected to be induced via the delivery site in membranes. We expect more advances in the dynamic NMR study, so that we can get insight into the mechanism of DD in membranes. 

There have been other MPC dynamics studies of hydrodynamic effects on the transport properties of colloidal suspensions [61-64]. In addition, vesicles that can deform under flow have also been investigated using hybrid MPC-MD schemes [65-69]. 

H. Noguchi and G. Gompper, Dynamics of vesicle self-assembly and dissolution, J. Chem. Phys. 125, 164908 (2006). 

Socaciu, C., C. Lausch, and H.A. Diehl. 1999. Carotenoids in DPPC vesicles Membrane dynamics. Spectrochim. Acta A Mol. Biomol. Spectrosc. 55 2289-2297. 

Sen P, Satoh T, Bhattacharyya K, Tominaga K (2005) Excitation wavelength dependence of solvation dynamics of coumarin 480 in a lipid vesicle. Chem Phys Lett 411(4—6) 339-344... 

The favourable properties which mark out vesicles as protocell models were confirmed by computer simulation (Pohorill and Wilson, 1995). These researchers studied the molecular dynamics of simple membrane/water boundary layers the bilayer surface fluctuated in time and space. The model membrane consisted of glycerine-1-monooleate defects were present which allowed ion transport to occur, whereby negative ions passed through the bilayer more easily than positive ions. The membrane-water boundary layer should be particularly suited to reactions which are accelerated by heterogeneous catalysis. Thus, the authors believe that these vesicles fulfil almost all the conditions required for the first protocells on earth ... 

This technique has permitted the dynamics of the exo-cytic/endocytic cycle to be investigated. At the neuromuscular junction, a readily releasable pool (RRP) and a reserve pool of vesicles coexist, the latter being released... 

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