Vesicle ghost

The removal of surfactants from polymer-coated vesicles and from composite cast bilayers to yield ghost vesicles and molecularly thick, two-dimensional polymer networks (detailed previously) illustrates a colloid-chemical approach to the construction of specific polymers. 

FIG. 11 Order parameter variation along acyl chains in red cell ghosts ( ), small unilamellar vesicles of egg phosphatidylcholine (V), and paraffin oil (+), as determined by the fluorescence anisotropy decay of the w-anthroyloxy fatty acid probes. (Reprinted by permission from Ref. 12.)... 

Several ILC studies covering drug interaction with liposomes and, correspondingly, proteoliposomes, cytoskeleton-depleted red blood cell membrane vesicles, red blood cell membranes, or red cells and ghosts have been reported (7,8,21-28,40,76,91,92,94). The log Ks values for interaction of... 

In this laboratory we have examined the ORD of various membrane systems including heavy beef heart submitochondrial vesicles, rat liver submitochondrial vesicles, erythrocyte ghosts, and the membranes of Micrococcus lysodeikticus, Halobacterium halobium, Halobacterium cuti-rubrum, and Mycoplasma laidlawii. The optical behavior of all these materials is strikingly similar the Cotton effects are similar to those produced by an a-helix but are red shifted to abnormally high wavelengths (71). Cotton effects arising from amide transitions in other... 

Figure 8-14 SDS-polyacrylamide gel electrophoresis of human erythrocyte ghosts. (A) From untreated cells. (B) From cells digested externally with chymotrypsin. (C) Inside-out vesicles prepared from cells pretreated with chymotrypsin. (D) The same inside-out vesicles after further treatment with chymotrypsin. (E) Polypeptides released hy the chymotryptic treatment of the inside-out vesides. The peptides are numbered according to the system of Steck232 Hb, hemoglobin. From Luna et al233...

Chaplin L, Cohen AH, Huettl P, Kennedy M, Njus D, Temperley SJ (1985) Reserpic acid as an inhibitor of norepinephrine transport into chromaffin vesicle ghosts. J Biol Chem 260 10981-10985. 

To gain insight into the effect of physical state and/or molecular organization on lipid oxidation, a variety of model systems have been used. These include dispersions, liposomes or vesicles (37,38), monolayers adsorbed on silica (39,40,41), and red blood cell ghosts (42). In most of these studies, oxidation was conducted at relatively low temperatures, i.e., 20 - 40°C. Very little information is available on the effects of physical state on high temperature oxidative reactions or interactions of lipids. 

Figure 2.5. BEIs of (a) the samples shocked at 27.4 GPa at room temperature, and (b) shocked at 84.0 GPa at room temperature. There are thin shock melt veins in the 27.4 GPa sample (indicated by arrows), one of which (middle) extends into the brecciated portion (br). Note the presence of remnant eucrite clasts (eucrite ghosts) composed of melted plagioclase and partly melted pyroxene, and veins of mixed-mineral melts (m, left). Light to medium gray pyroxene, dark gray plagioclase (glass), v vesicles.

Ruiz-Arguello et al. [91] were the first to point out that generation of ceramides in the bilayer induced efflux of vesicle or cell contents. They treated either large unilamellar vesicles consisting of sphingomyelin, phosphatidylethanolamine and cholesterol (at a 2 1 1 mole ratio), or resealed erythrocyte ghosts, both loaded with low-molecular mass fluorescent dyes, with bacterial SMase. In both cases, rapid efflux ensued in parallel with enzyme activity. This is in contrast with phosphatidylcholine phosphatidylethanolamine cholesterol (2 1 1) vesicles treated with phospholipase C, for which aqueous contents were not released. 

The transfer of radiolabeled phospholipids between vesicles and erythrocyte membranes could be used to assay lipid transfer activity. Intact erythrocytes are not an ideal substrate for routine measurements of transfer activity because some transfer proteins do not readily accelerate the transfer of phospholipids from these membranes. Van Meer et al. (1980) found that a very high concentration of the phosphatidylcholine-specific transfer protein was necessary to exchange the phosphatidylcholine of intact red blood cells. Erythrocyte ghosts are a more active substrate for this protein (Bloj and Zilversmit, 1976). However, the nonspecific transfer protein from bovine liver accelerates the exchange of phospholipid between intact erythrocytes and phosphatidylcholine vesicles (Crain and Zilversmit, 1980c). 

Erythrocytes (red blood cells) can be easily lysed to release their contents and yield membrane ghosts. These are large vesicles that represent a nearly pure preparation of the plasma membrane of the cells. The lipid composition and distribution between the inner and outer leaflets of the bilayer membrane are shown in Table 10.3 and Figure 10.15, respectively. 

Other systems which are currently studied as potential drug delivery systems are classified into two groups Firstly carriers which, by nature, form some kind of multi-or unilamellar vesicle, e.g. liposomes, erythrocyte ghosts, synthetic microcapsules, and secondly carriers based on naturally occurring macromolecules such as albumin, DNA, antibodies, Dextran (reviewed in Ref. >). 

It seems probable that the activation of an ATP-ase by Ca ions indicates that a transfer mechanism for Ca exists in the membranes of the ghosts. This transfer would be directed outwards. The efflux of calcium from ghosts is greater if ATP is added to the system. Moreover, salyrgan inhibits this phenomenon and the effective concentration is within the range of that found to inhibit the ATP-ase activity. 2,6-Dichlorophenol-indophenol. an inhibitor of the ATP-ase activated by Ca ions, prevents the accumulation of calcium in sarcoplasmic vesicles. 

Cobalt (II) as a shift reagent has been employed to visualize the Cl" resonance from chloride ions inside vesicles and erythrocyte ghosts. The latter observation allowed measurements of the kinetics of chloride/sulfate exchange mediated by the band III protein. The same group also used Co(II) to observe Cl" inside the cells of an alga, Chlorella pyrenoidosa and inside the cells of a suspension of cultured plant cells from Nicotiana tobbaccum. In both of these... 

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