James W. Heath

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A new rapid method for fractionation of crude synaptosomes (postmitochondrial pellet, P2) on a discontinuous 4-step Percoll gradient is described. The homogeneity and integrity of the 5 major subcellular fractions were determined by analysis of the distribution of protein, lactate dehydrogenase, cytochrome oxidase, pyruvate dehydrogenase, synapsin I (a(More)
A method for preparation of synaptosomes from rat cerebral cortex, on a discontinuous Percoll gradient, was previously developed for use with a P2 pellet (Brain Research, 372 (1986) 115-129). Here the Percoll method has been adapted for use with an S1-supernatant which eliminates a potentially damaging resuspension step and saves over 30 min, representing a(More)
The Trembler mouse has a dysymelination of peripheral nerves that includes hypomyelination, failure of myelin compaction, and demyelination/remyelination. We have localized the myelin proteins P0 and myelin associated glycoprotein in Trembler peripheral nerve and correlated their distributions with the ultrastructure of myelin internodes.(More)
1. The structure of sympathetic neurones in the rat has been examined with histological, fluorescence histochemical and electron microscopical methods after chronic treatment for 6 weeks with guanethidine (25 or 30 mg/kg/day i.p.).2. Less than 2% of the nerve cell bodies in the superior cervical ganglion remained at this time and in these cells the(More)
In experimental studies addressing the regulation of myelin formation and maintenance by Schwann cells, the sympathetic nervous system of young adult rodents has served a key role as an essentially nonmyelinated yet modifiable control tissue. Nevertheless there is clear evidence of substantial myelination in the superior cervical ganglion (SCG) of normal(More)
We have shown that the synapse maturation phase of synaptogenesis is a model for synaptic plasticity that can be particularly well-studied in chicken forebrain because for most forebrain synapses, the maturation changes occur slowly and are temporally well-separated from the synapse formation phase. We have used the synapse maturation phase of neuronal(More)
Axonal contact plays a critical role in initiating myelin formation by Schwann cells. However, recent studies of "double myelination" have indicated that myelin maintenance continues in Schwann cells completely displaced from physical contact with the axon. This raises the possibility either that diffusible trophic factors are produced by the axon, or that(More)
Aqueous solutions combining a high concentration of formaldehyde (4%) with low concentrations of glutaraldehyde (0.5–1%) have been used to simultaneously localize amines by the formation of fluorescent products and to fix central nervous tissue for electron microscopy. The fluorescence reaction is produced by the aldehyde mixture at room temperature and the(More)
Relationships between axons and Schwann cells in myelinated fibres of the superior cervical (sympathetic) ganglion have been examined in normal adult rats. In cross-sections through the ganglion up to 4% of myelinated fibres were focally encircled by an additional myelinating Schwann cell, forming regions termed 'double myelination'. In these regions and(More)
This study has examined the structural features and distribution of 'doubly myelinated' axons in normal adult and aged mice. Investigation focused on the superior cervical ganglion (SCG) and paravertebral sympathetic ganglia, which were extensively serial-sectioned for light and electron microscopy. In the SCG, the principal features of doubly myelinated(More)