Magnetic orientation of sphingomyelin-lecithin bilayers

Speyer, Julia B.; Sripada, Pavanaram K.; Gupta, S. K. Das; Shipley, G. Graham; Griffin, Robert G.

doi:10.1016/s0006-3495(87)83394-5

Cited by 88 publications

(63 citation statements)

References 12 publications

(19 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Anisotropic magnetic susceptibility is a phenomenon commonly seen in crystals of highly anisotropic atomic structure. It also has been noted in constituents of biological tissues, including muscle fibers (17), retinal rods (18), nucleic acids (19), proteins (20)(21)(22)(23), and lipid bilayers (24)(25)(26)(27). Because the proteins and lipid bilayers associated with white matter fibers are highly ordered, anisotropic susceptibility may have contributed to our present findings.…”

Section: Discussionsupporting

confidence: 66%

Sensitivity of MRI resonance frequency to the orientation of brain tissue microstructure

Lee

Shmueli²,

Fukunaga³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

249

316

View full text Add to dashboard Cite

Recent advances in high-field (≥7 T) MRI have made it possible to study the fine structure of the human brain at the level of fiber bundles and cortical layers. In particular, techniques aimed at detecting MRI resonance frequency shifts originating from local variation in magnetic susceptibility and other sources have greatly improved the visualization of these structures. A recent theoretical study [He X, Yablonskiy DA (2009) Proc Natl Acad Sci USA 106:13558–13563] suggests that MRI resonance frequency may report not only on tissue composition, but also on microscopic compartmentalization of susceptibility inclusions and their orientation relative to the magnetic field. The proposed sensitivity to tissue structure may greatly expand the information available with conventional MRI techniques. To investigate this possibility, we studied postmortem tissue samples from human corpus callosum with an experimental design that allowed separation of microstructural effects from confounding macrostructural effects. The results show that MRI resonance frequency does depend on microstructural orientation. Furthermore, the spatial distribution of the resonance frequency shift suggests an origin related to anisotropic susceptibility effects rather than microscopic compartmentalization. This anisotropy, which has been shown to depend on molecular ordering, may provide valuable information about tissue molecular structure.

show abstract

Section: Discussionsupporting

confidence: 66%

Sensitivity of MRI resonance frequency to the orientation of brain tissue microstructure

Lee

Shmueli²,

Fukunaga³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

249

316

View full text Add to dashboard Cite

show abstract

“…Similar characteristics have been reported with other mixtures including charged lipids, such as POPE-POPG [38], and they were attributed to partial orientation of the bilayers in the magnetic field. It was otherwise suggested [21] that addition of a positively charged polypeptide could have a screening effect upon the negatively charged bilayers, leading to a partial dehydratation and to transition from unilamellar [39,40] to multilamellar liposomes. Here, the same effect was obtained with spectrin, a protein with overall negative charge.…”

Section: Discussionmentioning

confidence: 99%

Weak interaction of spectrin with phosphatidylcholine‐phosphatidylserine multilayers: A ²H and ³¹P NMR study

et al. 1989

View full text Add to dashboard Cite

Spectrin from human erythrocytes binds to bilayer dispersions of both DMPC and DMPSDMPC (I: 1, w/w). However, no effect of bound spectrin on the conformation of the lipid head groups, as measured from the deuterium quadrupolar splittings of DMPC or DMPS specifically deuterated in the polar head groups, was detected in I:1 mixtures of the two lipids containing either deuterated DMPC or DMPS. Neither the phase transition of the DMPS:DMPC mixtures, nor the spin-lattice relaxation time (T,) of the deuterated DMPS head group, was affected by spectrin. These results argue against any strong interaction of spectrin with phosphatidylserine and rule out the possibility that spectrin is responsible for the maintainance of PS in the inner monolayer of the erythrocyte membrane during the whole life-span of this cell.

show abstract

“…All specta have a line shape characteristic of a lipid bilayer. The low field shoulder in some of the spectra is undetectable, suggesting partial liposome orientation in the magnetic field (Seelig et al 1985;Speyer et al 1987;Roux et al 1988). The same characteristic spectra were obtained for temperatures between 5 °C and 37 °C (data not shown).…”

Section: Nmr Experimentsmentioning

confidence: 99%

Lateral diffusion of erythrocyte phospholipids in model membranes comparison between inner and outer leaflet components

Cribier

Morrot

et al. 1990

Eur Biophys J

View full text Add to dashboard Cite

The physical properties of lipid bilayers with a similar composition to the outer and inner leaflets of the human erythrocyte membrane have been examined in protein-free model systems. The outer leaflet (OL) was represented by a phospholipid mixture containing phosphatidylcholine and sphingomyelin extracted from human erythrocytes, while a mixture of phosphatidylcholine, phosphatidylserine and phosphatidylethanolamine represented the inner leaflet (IL). The ratio of cholesterol to phospholipid was varied in both mixtures. The lateral diffusion coefficient of fluorescent phospholipids diluted in such lipid mixtures was determined by the modulated fringe pattern photobleaching technique. Contrast curves with a single exponential decay, indicative of homogeneous samples, were obtained only for temperatures above 15 degrees C and for a cholesterol to phospholipid molar ratio below 0.8. The rate of lateral diffusion was approximately five times faster in IL than in OL multilayers, in agreement with former results obtained in human erythrocytes (Morrot et al. 1986). Varying the cholesterol to phospholipid ratio from 0 to 0.8 (mol/mol) enabled us to decrease the diffusion constant by only a factor of approximately 2 for both IL and OL mixtures. The order parameter of a spin-labeled phospholipid was determined in the different systems and found to be systematically smaller in IL mixtures than in OL mixtures. The present study indicates that the difference in lipid diffusivity of the two erythrocyte leaflets may be accounted for solely by a difference in phospholipid composition, and may be independent of cholesterol and protein asymmetry.

show abstract

Magnetic orientation of sphingomyelin-lecithin bilayers

Cited by 88 publications

References 12 publications

Sensitivity of MRI resonance frequency to the orientation of brain tissue microstructure

Sensitivity of MRI resonance frequency to the orientation of brain tissue microstructure

Weak interaction of spectrin with phosphatidylcholine‐phosphatidylserine multilayers: A ²H and ³¹P NMR study

Lateral diffusion of erythrocyte phospholipids in model membranes comparison between inner and outer leaflet components

Contact Info

Product

Resources

About

Magnetic orientation of sphingomyelin-lecithin bilayers

Cited by 88 publications

References 12 publications

Sensitivity of MRI resonance frequency to the orientation of brain tissue microstructure

Sensitivity of MRI resonance frequency to the orientation of brain tissue microstructure

Weak interaction of spectrin with phosphatidylcholine‐phosphatidylserine multilayers: A 2H and 31P NMR study

Lateral diffusion of erythrocyte phospholipids in model membranes comparison between inner and outer leaflet components

Contact Info

Product

Resources

About

Weak interaction of spectrin with phosphatidylcholine‐phosphatidylserine multilayers: A ²H and ³¹P NMR study