Plos One
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Miniaturization of active implantable medical devices is currently compromised by the available means for electrically powering them. Most common energy supply techniques for implants--batteries and inductive couplers--comprise bulky parts which, in most cases, are significantly larger than the circuitry they feed. Here, for overcoming such miniaturization bottleneck in the case of implants for electrical stimulation, it is proposed to make those implants act as rectifiers of high frequency bursts supplied by remote electrodes. ⋯ The present study numerically demonstrates that low frequency currents capable of stimulation can be produced by a miniature device behaving as a diode when high frequency currents, neither capable of thermal damage nor of stimulation, flow through the tissue where the device is implanted. Moreover, experimental evidence is provided by an in vivo proof of concept model consisting of an anesthetized earthworm in which a commercial diode was implanted. With currently available microelectronic techniques, very thin stimulation capsules (diameter <500 µm) deliverable by injection are easily conceivable.
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All the opinions in this article are those of the authors and should not be construed to reflect, in any way, those of the Department of Veterans Affairs. ⋯ The peer review process largely succeeds in selecting high impact articles and dispatching lower impact ones, but the process is far from perfect. While the inter-rater reliability between individual reviewers is low, the accuracy of sorting is improved with a greater number of reviewers.
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Retinal ganglion cells expressing the photopigment melanopsin are intrinsically photosensitive (ipRGCs). These ganglion cell photoreceptors send axons to several central targets involved in a variety of functions. Within the retina ipRGCs provide excitatory drive to dopaminergic amacrine cells via glutamatergic signals and ipRGCs are coupled to wide-field GABAergic amacrine cells via gap junctions. However, the extent to which ipRGCs are coupled to other retinal neurons in the ganglion cell layer via gap junctions is unclear. Carbenoxolone, a widely employed gap junction inhibitor, greatly reduces the number of retinal neurons exhibiting non-rod, non-cone mediated light-evoked Ca(2+) signals suggesting extensive intercellular coupling between ipRGCs and non-ipRGCs in the ganglion cell layer. However, carbenoxolone may directly inhibit light-evoked Ca(2+) signals in ipRGCs independent of gap junction blockade. ⋯ We demonstrate that the light-evoked rise in [Ca(2+)](i) in isolated mammalian ganglion cell photoreceptors is inhibited by carbenoxolone. Since the light-evoked increase in [Ca(2+)](i) in isolated ipRGCs is almost entirely due to Ca(2+) entry via L-type voltage-gated calcium channels and carbenoxolone does not inhibit light-evoked action potential firing in ipRGCs in situ, carbenoxolone may block the light-evoked increase in [Ca(2+)](i) in ipRGCs by blocking L-type voltage-gated Ca(2+) channels. The ability of carbenoxolone to block evoked Ca(2+) responses must be taken into account when interpreting the effects of this pharmacological agent on retinal or other neuronal circuits, particularly if a change in [Ca(2+)](i) is the output being measured.
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Tissue-engineered nerve scaffolds hold great potential in bridging large peripheral nerve defects. However, insufficient vascularization of nerve scaffolds limited neural tissues survival and regeneration, which hampered the successful implantation and clinical application of nerve scaffolds. The omentum possesses a high vascularization capacity and enhances regeneration and maturation of tissues and constructs to which it is applied. However, combined application of nerve scaffolds and omentum on axonal regeneration and functional recovery in the treatment of large peripheral nerve defects has rarely been investigated thus far. ⋯ These findings indicate that the omentum-wrapped scaffold is capable of enhancing axonal regeneration and functional recovery, which might be served as a potent alternative to nerve autografts. The beneficial effect of omentum-wrapping on nerve regeneration might be related with the proteins produced by omentum.
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Our knowledge about affective processes, especially concerning effects on cognitive demands like word processing, is increasing steadily. Several studies consistently document valence and arousal effects, and although there is some debate on possible interactions and different notions of valence, broad agreement on a two dimensional model of affective space has been achieved. ⋯ Moreover, these effects even persist in an experiment with discrete emotion conditions when the stimuli are controlled for emotional valence and arousal levels. We interpret this result as evidence for discrete emotion effects in visual word recognition that cannot be explained by the two dimensional affective space account.