Electrophysiology of Purkinje neurons in the weaver mouse: iontophoresis of neurotransmitters and cyclic nucleotides, and stimulation of the nucleus.

We compared the Purkinje cells of adult normal and weaver mutant (wv/wv) mice by iontophoretic and electrophysiological tests. Although weaver Purkinje cells fire spontaneously at a rate (38 Hz) similar to normal mouse neurons (40 Hz), several abnormalities of firing were seen: high frequency bursts of single (simple) spikes occurred in 5-10-sec episodes in 38% of weaver cells, compared to 8% in normal mice; spontaneous complex spikes (climbing fiber-like burst responses) occurred in several different forms in a given Purkinje cell. As in normal mice and rats, the spontaneous single spike activity is readily depressed by electrical stimulation of the locus coeruleus, the presumed source of a dense noradrenergic plexus in the weaver cerebellar cortex. In a preliminary experiment the adrenergic blocking agent, fluphenazine, antagonized the responses to locus coeruleus stimulation. Iontophoresis of norepinephrine (NE), GABA and serotonin (5-HT) also uniformly depressed Purkinje cell single spike activity in all normal and weaver mice; cyclic AMP depressed 55% of normal and 70% of weaver Purkinje cells. Glutamate was always excitatory. The only qualitative difference was seen with acetylcholine, which was mostly inhibitory in normal mouse, but increased the firing rate in 42% of weaver Purkinje neurons. Cyclic GMP was predominantly excitatory in both types. Thus, despite the absence of parallel fibers, weaver Purkinje neurons grossly resemble normal Purkinje cells electrophysiologically as well as morphologically. Since several sites of indirect presynaptic actions are eliminated in weaver, our results further substantiate the direct post-synaptic inhibitory nature of GABA, 5-HT and NE, and the noradrenergic pathway from locus coeruleus to Purkinje cells. Similarly, consistent inhibitory responses to cyclic AMP in the weaver support the previously hypothesized role of cyclic AMP in the post-synaptic inhibitory response to NE.

Xanya Sofra Weiss

Xanya Sofra Weiss

Wound Closure After Split-Thickness Skin Grafting Is Accelerated With the Use of Continuous Direct Anodal Microcurrent Applied to Silver Nylon Wound

Wound healing after graft closure of excised burn wounds is a critical factor in the recovery process after thermal injury. Processes that speed time to stable wound closure should lead to improved outcomes, shorter lengths of hospital stays, and decreased complications. A randomized clinical trial to test the ability of continuous direct anodal microcurrent application to silver nylon wound contact dressings was designed. Time for wound closure after split-thickness skin grafting was observed. Thirty patients with full-thickness thermal burns were randomized into two groups. The control group received postoperative dressing care using moistened silver nylon fabric covered with gauze after tangential burn wound excision and split-thickness skin grafting. The study group received an identical protocol with the addition of continuous direct anodal microcurrent application. Time to 95% wound closure was measured using digital photography. The digital photographs were evaluated by a burn surgeon blinded to the patient's randomization. An independent t-test was used to analyze the data. The study group experienced a 36% reduction in time to wound closure (mean of 4.6 days) as compared to the control group (mean of 7.2 days). This was statistically significant at a P value of <.05. The use of continuous direct anodal microcurrent decreased time to wound closure after split-thickness skin grafting.

Xanya Sofra Weiss

Xanya Sofra Weiss