Differential effects of various electrical parameters on peripheral and central nerve regeneration.

Optimal factors for small DC current electrical stimulation for nerve regeneration were studied. These studies are consistent with previous data and values expected for a return of function following Peripheral Nervous System (PNS) damage. This work represents the first detailed investigation of a dose response in the PNS using applied electric fields.

Enhanced survival of full-thickness skin grafts following the application of DC electrical fields.

The present study was undertaken to determine if uses of exogenous electrical fields could improve the posttraumatic quality of dermis and epidermis in isolated grafts in the rat. In blinded procedures, a full-thickness area of skin was removed and reattached to the original site. A galvanic device delivering 4.

The short-term effects of delayed application of electric fields in the damaged rodent spinal cord.

Previous studies have indicated that the application of electrical fields to the contused rat spinal cord could result in a partial return of function within 3 weeks after injury/treatment. Whether similar functional recovery could be established after a delay in the treatment was investigated. Rat spinal cords were contused and allowed to recover untreated for 10 days.

Developing retina and PNS segments for transplantation into the adult host eye: reconstruction of the mammalian visual system. 2. Results.

The previous companion paper detailed a technique which allowed embryonic retinal ganglion cell axons to grow from the anterior eye chamber across a PNS bridge, and enter the adult host forebrain. Embryonic eyes of E11, E14, E18 and E21 animals were sutured to a PNS bridge, the embryonic eye implanted into an adult host eye, and the distal end of the bridge implanted into the host forebrain. Results indicate that when eyes of all ages are used for implantation, axons could be observed to grow from the embryonic retina, through the bridge and into the adult host forebrain.

Developing retina and PNS segments for transplantation into the adult host eye: reconstruction of the mammalian visual system. 1. Methodology.

Various techniques have been explored to determine the uses and limitations of techniques that enable the adult CNS to regenerate, but relatively little attention has been given to the consideration of a "reconstructed" visual system. Using this approach, one can design experiments to study the uses of exogenous tissues in reestablishing neuronal circuits that have been damaged. Toward this end, experiments were designed to determine whether embryonic retinal ganglion cells can project axons into a grafted PNS "bridge", and enter adult host targets that were partially deafferented.

Short term efficacy of applied electric fields in the repair of the damaged rodent spinal cord: behavioral and morphological results.

The short term effects of electric fields applied exogenously to the contused rat spinal cord were studied in a blind experiment. A DC field using 3 microA was applied to the dorsal cord when the lesion was made, and rats were behaviorally tested weekly for up to 3 weeks on an inclined plane. The results show that the "cathode rostral" orientation group of animals performed statistically significantly better on the inclined plane than either the "anode rostral" or the "no current" group.

Mammalian optic nerve regeneration following the application of electric fields.

Previous studies have shown that the application of electric fields to the damaged mammalian nervous system is efficacious in promoting regeneration of peripheral nervous system axons. The present experiments were undertaken to determine whether exogenously applied electric fields can induce regenerative responses in the damaged mammalian central nervous system (CNS). In these studies, chronically delivered direct current was applied to the optic nerve, orienting the cathode distal to the lesion site.

Facilitated regeneration in the rat peripheral nervous system using applied electric fields.

The efficacy of applied electric fields in promoting regeneration of the transected and frozen rat sciatic nerve was studied. Three groups were studied at 6, 12, and 18 days post-lesion; nerves treated with 1.5 microA of direct current where the cathode was oriented distal to the lesion, nerves treated with the anode distal to the lesion, or no current delivered to the nerve.

Treatment of the damaged rat hippocampus with a locally applied electric field.

Previous studies have indicated that axons may be directed to regenerate toward the cathodal source of a locally applied D.C. electric field.

Regeneration in the mammalian nervous system using applied electric fields: a literature review.

The application of weak electric fields on the damaged peripheral and central nervous systems will promote recovery of function in animal models. The effect of the electric field appears to facilitate the growth and orientation of regenerating neurites towards the cathodal pole in a DC field. Thus, provided the correct parameters are utilized, facilitation of regeneration in the human peripheral and even central nervous system appears possible.

Posttranslational protein modification by polyamines in intact and regenerating nerves.

A 150,000-g supernatant from axoplasm of the giant axon of the stellate nerve of the squid and from rat sciatic and goldfish optic nerves was found to be able to incorporate covalently [3H]putrescine and [3H]spermidine into an exogenous protein (N,N'-dimethylcasein). Incorporation of radioactivity was inhibited by CuSO4, a specific inhibitor of transglutaminases, the enzymes mediating these reactions in other tissues. Analysis of pH and temperature range and enzyme kinetics displayed characteristics predicted for transglutaminase-mediated reactions.

Posttranslational protein modification by amino acid addition in regenerating optic nerves of goldfish.

Previous experiments have demonstrated that 4S RNA, (tRNA), is transported axonally during the reconnection and maturation of regenerating optic nerves of goldfish. The present experiments were performed to determine if tRNA is transported axonally during elongation of these regenerating nerves and whether, as has been demonstrated in other systems, it participates in posttranslational protein modification (PTPM). [3H]Uridine was injected into both eyes of fish with intact optic nerves and 0, 2, 4, or 8 days after bilateral optic nerve cut.

RNA content of normal and axotomized retinal ganglion cells of rat and goldfish.

The responses of rat and goldfish retinal ganglion cells to axotomy were examined by a quantitative cytochemical method for RNA and by morphometric measurement 1-60 (rat) and 3-90 (goldfish) days after interruption of one optic nerve or tract intracranially. Unoperated control animals were studied also. The RNA content of axotomized neurons of rat fell 7-60 days postoperatively.

Posttranslational protein modification by amino acid addition in intact and regenerating axons of the rat sciatic nerve.

Experiments were performed to determine whether posttranslational addition of amino acids to axonal proteins occurs in axons of the rat sciatic nerve. Two ligatures were placed 1 cm apart on sciatic nerves. Six days later, segments proximal to each ligature were removed, homogenized, centrifuged at 150,000 X g, and analyzed for the ability to incorporate 3H-amino acids into proteins.

Evidence that multiple species of aminoacylated transfer RNA are present in regenerating optic axons of goldfish.

This study reports that 4S RNA present in regenerating optic axons of goldfish is likely to be transfer RNA. Evidence is also presented which indicates that this transfer RNA is similar to transfer RNA found in tectal cells and that its aminocylation is likely to occur both in retinal ganglion cells prior to axonal transport as well as in the axon itself. Fish with regenerating optic nerves received intraocular injections of [3H]uridine followed 4 days later by intracranial injections of [14C]uridine.

Incorporation of 3H-amino acids into proteins in a partially purified fraction of axoplasm: evidence for transfer RNA-mediated, post-translational protein modification in squid giant axons.

Transfer RNA (tRNA) has been demonstrated to be present in axons of both invertebrates and the higher vertebrates, but nothing is known of its role in the metabolism of the axon. The present experiments were performed to determine whether tRNA functions in axons as a participant in post-translational protein modification of endogenous proteins. RNA was extracted from the axoplasm of squid giant axons and incubated with a variety of 3H-amino acids, aminoacyl-tRNA synthetases (obtained from squid optic lobe), and an appropriate reaction mixture.

Incorporation of (3H) lysine into the brain and spinal cord of the cebus (Cebus appella) and rhesus (Macacca mulata) monkeys.

The relative amounts of incorporation of [3H] lysine into various brain areas and segments of the spinal cord in adult Cebus and Rhesus monkeys were studied. One hour after subcutaneous injection of [3H] lysine, animals were sacrificed and the brain and spinal cord samples taken and processed for [3H] lysine incorporation into protein (Lowry et al., 1951; Wells and Bernstein, 1976).