| Abstract: | Abstract— Frozen and unfrozen bovine brains were used to determine the extent of in situ degradation of myelin basic protein. The following three parameters were investigated. (1) The time interval between death and sampling of the tissue, (2) the effective temperature of the tissue during this interval, and (3) the effect of freezing and thawing on the subsequent autolysis of myelin basic protein. Polyacrylamide gel electrophoresis was carried out on unfrozen white matter solubilized with phenol-formic acid–water. The resulting electrophoretic pattern showed no qualitative changes in the myelin basic protein after tissue incubation at 4° or 23°C for up to 24 h. When myelin basic protein was extracted, purified and quantitated, there was no apparent decrease within 24 h of incubation at 23°C. However, if the tissue was frozen and thawed prior to incubation, there was a rapid disappearance of myelin basic protein such that only 10% remained after 24 h of incubation. Basic protein extracted from frozen or unfrozen tissue that had undergone autolysis for up to 24 h was found to be encephalitogenic in guinea pigs. Electron microscopy of frozen and thawed material showed separation and fraying of myelin lamellae. It is postulated that the above morphological changes probably render the basic protein readily accessible to proteolytic enzymes. |
