ABSTRACT In Multiple Sclerosis (MS) and Experimental Allergic Encephalomyelitis (EAE) in the common marmoset, demyelination appears to result from loss of adhesion between adjacent myelin lamellae and the formation of small myelin vesicles. Although proteins are involved in maintaining normal myelin structure, lipids may play an essential role in myelin stability. In the current study we focused on the effect that disturbed ratios of sphingomyelin (SM) and cholesterol may have on the regular distribution of those molecules. Mixtures of egg SMs (saturated) and bovine brain SMs (partially unsaturated) with cholesterol were made and examined with Langmuir isotherms. The cholesterol-induced condensations of the average molecular areas were determined by classic mean molecular area vs. composition plots. The results showed that egg SMs are significantly more expanded than bovine brain SMs, contrary to the fact that they are more saturated. We believe this is due to the fact that two-dimensional phase transitions of the predominant acyl chain species of egg SM generally occur at lower pressures compared to the predominant species in bovine brain SM due to their shorter acyl chain lengths. Furthermore we found that just beyond 22.2 mol% cholesterol, a predicted superlattice concentration, the condensation effect of cholesterol dramatically increases. We explain this by the fact that just beyond this point, the membrane regions containing only SM molecules have completely disappeared.

In this study we used organotypic cerebellar slice cultures from neonatal rat pups in combination with scanning laser confocal microscopy to monitor the cellular events associated with the formation of central nervous system (CNS) myelin. Our images showed the migration of neural precursor cells, differentiation of these cells into glial cells and neurons, and the subsequent myelination of neuronal axons. Both light and confocal microscopy provided valuable information on morphological changes associated with neural differentiation and the formation of CNS tissue. The combined use of confocal microscopy with cerebellar slice cultures holds promise for evaluating the effects of agents that promote myelination. This in turn will help with understanding of demyelination and myelin repair in disorders such as multiple sclerosis and spinal cord injury.

The Young Investigators’ Program was a four-year biomedical research mentorship program aimed at providing advanced high school students the opportunity to actively participate in university-level research at the University of California, Santa Barbara. After three years the program had undergone many changes in its curriculum to evolve into its successful multidisciplinary format. Students were found to respond better to a structured, point-based system rather than a less formal approach, and four students contributed to research that is being submitted for publication. This program could serve as a model for establishing future university-community collaborative mentorship programs.