Antiserum to cerebroside was prepared in rabbits by injection of cerebroside together with bovine serum albumin in complete Freund's adjuvant. When applied to cultures of embryo mouse spinal cord at explantation, this antiserum inhibited sulfatide synthesis and myelination; when applied to myelinated cultures it inhibited sulfatide synthesis and produced demyelination. Complement fixation assays also show antibody to cerebroside in serums from rabbits with experimental allergic encephalomyelitis induced by injection of whole white matter. Absorption of such serum with cerebroside abolishes the inhibiting and demyelinating activities.

The activity of the myelin-associated enzyme 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) was measured in 14 rat tissues and in subcellular fractions of rat liver by a sensitive fluorometric method, using cyclic NADP as substrate. CNP activity in brain (339 mumol/h/mg protein) was fourfold that of the sciatic nerve. The activities in tissues outside the nervous system ranged from a low of 0.42 mumol/h/mg protein in the unwashed red blood cell to a high of 9.96 in the spleen. The activity was highest in tissues containing cells with membranes capable of undergoing transformation and elaboration (spleen and thymus) and low in those in which the cell membranes are morphologically stable (muscle and red cell). The enzyme was found in all major liver subfractions, with the highest activities in the microsomal and nuclear fractions. Despite the large difference in the maximal velocities of CNP in brain and liver, the affinity of the liver enzyme for the substrate (km) was similar to that of brain enzyme. Brain CNP was stable over a 48-h postmortem period.

Interpretation of biochemical measurements in the human brain after death is complicated by a variety of premortem, perimortem, and postmortem factors. The activity of glutamic acid decarboxylase (GAD) in particular has been found to vary considerably among human brains. In contrast to neurotransmitter-associated enzymes, metabolic enzymes are present in all brain cells and should not be specifically lost by patterned neuronal cell loss such as that which occurs in Parkinson disease. We compared the activity of GAD to that of the metabolic enzymes creatine kinase (CK), adenylate kinase, hexokinase, beta-glucuronidase, and malate, lactate, glucose-6-phosphate, and isocitrate dehydrogenases in 24 regions of six human brains. Of the metabolic enzymes, only CK showed a 5-fold variation approaching that of GAD. Like GAD, CK activity was stable postmortem, but its activity was apparently inversely related to the severity and duration of the preterminal illness. CK may be a useful marker of agonal deterioration.