No abstract available

[en] This assay is a quick and sensitive method for determination of antibodies to galactocerebroside (GC). The use of antibody-plus-complement radioisotope release from GC-bearing liposomes allows numerous samples to be handled in semi-automated fashion. By substituting alternative gangliosides or cerebrosides, the technique may be simply modified for assay of antibodies to other substances. (Auth.)

[en] The axially symmetric powder pattern 2H-nuclear magnetic resonance (NMR) lineshapes observed in the liquid crystalline phase of pure lipid or lipid/cholesterol bilayers are essentially invariant to temperature, or, equivalently, to variations in the correlation times characterizing C-2H bond reorientations. In either of these melted phases, where correlation times for C-2H bond motions are shorter than 10(-7) s, information on the molecular dynamics of the saturated hydrocarbon chain would be difficult to obtain using lineshape analyses alone, and one must resort to other methods, such as the measurement of 2H spin-lattice relaxation rates, in order to obtain dynamic information. In pure lipid bilayers, the full power of the spin-lattice relaxation technique has yet to be realized, since an important piece of information, namely the orientation dependence of the 2H spin-lattice relaxation rates is usually lost due to orientational averaging of T1 by rapid lateral diffusion. Under more favorable circumstances, such as those encountered in the lipid/cholesterol mixtures of this study, the effects of orientational averaging by lateral diffusion are nullified, due to either a marked reduction (by at least an order of magnitude) in the diffusion rate, or a marked increase in the radii of curvature of the liposomes. In either case, the angular dependence of 2H spin-lattice relaxation is accessible to experimental study, and can be used to test models of molecular dynamics in these systems. Simulations of the partially recovered lineshapes indicate that the observed T1 anisotropies are consistent with large amplitude molecular reorientation of the C-2H bond among a finite number of sites

No abstract available

[en] The experiment was performed on rats to which a single injection of [U-¹⁴C]glucose had been administered. Results were observed from the 7th to the 281st day following contamination. At 280 days only lipids in the brain contained radioactivity, the highest degree of specific activity being found in the cerebrosides

[en] Methyl iodide-¹⁴C was condensed with 2-(1-lithio-hept-1-yn-6-yl) 1,3-dioxolanne in presence of HMPT and benzene to give 2-(oct-2-yn-8-yl-1-¹⁴C) 1,3-dioxolanne. Catalytic reduction, followed by acid hydrolysis led to pelargonic aldehyde 9-¹⁴C. Condensation of this aldehyde with an excess of ω-carbomethoxy-tetradecylidene, triphenyl phosphorane produced methyl nervonate 24-¹⁴C. The latter was isolated from its trans isomer by chromatography on a silver nitrate impregnated silicagel column. Finally, nervonic acid 24-¹⁴C was obtained by alkaline hydrolysis (specific activity : 52 mCi/mMole) with an overall yield of 7% based on methyl iodide-¹⁴C. (author)

No abstract available

[en] A convenient and rapid method for the separation of [³H] cerebroside based on the use of small columns of DEAE cellulose is described. (Auth.)

[en] This paper compares different approaches, reported in the literature, for obtaining thermodynamic statistical information from ESR and NMR measurements on the conformations of lipid bilayers. A statistical approach recently proposed by the authors has been employed to reexamine several literature values of order parameters and to calculate Helmholtz free energy and entropy. This approach was applied to egg-phosphatidycholine, cerebroside and gangliosoyds, spin labelled at different acyl chain positions, and to bilayered membranes containing phosphatidylcholine and different gangliosides (GM1, GD1a and GD1b) at increasing glycolipid mole percent. The variation of the stability of the membrane with the peroxidation is also reexamined at different intermembrane locations by various probes

[en] A new procedure for introducing tritium into the carbohydrate portions of glucosyl- and galactosylceramides was developed using a new catalyst, CrO3-graphite, which specifically oxidizes the primary alcohol group to the aldehyde. About 10% of the glycolipid was converted to the aldehyde and the aldehyde produced was then reduced back to the original form with KB3H4. After methanolysis, more than 96.7% of the radioactivities of [3H]glucosyl- and [3H]galactosylceramides were found to be located in the carbohydrate portions, and the specific activities of the [3H]galactosyl- and [3H]glucosylceramides were 2.08 to 4.30 X 10(4) cpm/nmol, which could be increased greatly by purifying the aldehydes and reducing them with KB3H4. In addition, beta-galactosidase activity was successfully determined with [3H]galactosylceramide as the enzyme substrate; the Km was 18.73 mM and the Vmax was 11.63 nmol/mg/h, indicating that no significant structural modification occurs during the oxidation