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Dawn and dusk simulation as a therapeutic intervention 总被引:1,自引:0,他引:1
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In thePseudemys turtle retina five functionally distinct, electrically coupled networks of horizontal cells distribute signals in the outer plexiform layer. These networks differ significantly in their architecture, as determined by intracellular labeling with Neurobiotin after physiological recording and identification. The density of H1 horizontal cells is highest, ranging around 1800 cells/mm2 at approximately 2.3 mm eccentricity. H1 horizontal cell somata are connected via 6–10 thin, short dendrites. The H1 horizontal cell axon terminal network is composed of thick axon terminals, forming a three-dimensional, sheath-like structure. Networks of coupled H2 and H3 horizontal cells have cell densities of around 210 cells/mm2 and 350 cells/mm2 respectively, at the same eccentricity of 2.3 mm. Cell bodies are connected with 6–12 long, thin dendrites. Here we report for the first time H4 horizontal cell networks. Cell density is approximately 970 cells/mm2 at 2 mm eccentricity, and cell bodies are connected with 6–10 thin, short dendrites. General properties of passive voltage spread were compared for three of these horizontal cell networks using NeuronC. Realistic network architectures were obtained by digitizing the intracellularly labeled networks, respectively. One network obtained from coupled H1 horizontal cell bodies, one from coupled H1 horizontal cell axon terminals, and one from H2 horizontal cells were simulated. These three realistic networks were compared with an artificial, electrically coupled regular triangular network. Passive signal spread in these networks strongly depended on the exact network architecture using otherwise identical parameters. Changes in coupling strength affected signal spread in these networks differently. As in the experimental situation, changes in synaptic conductance influenced signal spread. Some principal effects of extensively coupled horizontal cells on photoreceptor signal processing were simulated with one type of photoreceptor connected by telodendria, synapsing onto an underlying triangular network and receiving feedback synapses. Under certain conditions, spatial information is coded in single photoreceptors. This was also the case in the experimental situation. In the simulation, spatial filter adjustment for optimal spatial coding in photoreceptors can be achieved by changing coupling strength in the horizontal cell network. 相似文献
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Although the external rhinoplasty remains controversial it is difficult to understand why. The columella scar is of little significance since this becomes nearly invisible if the closure is carefully performed. There is a relative postoperative prolongation of nasal tip swelling in comparison with the closed technique, however this also becomes negligible with time. On the other hand, in our experience the open approach will achieve better understanding of the patient's individual anatomy and thus lead to a more predictable result through increased exposure and precision tailoring. The external technique facilitates the application of the great variety of tip refinements that have been developed over the years to allow facial plastic surgeons to get consistently excellent results in rhinoplasty. 相似文献
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Inversion lateral ankle trauma: differential diagnosis, review of the literature, and prospective study 总被引:1,自引:0,他引:1
M Perlman D Leveille J DeLeonibus R Hartman J Klein R Handelman E Schulz S Wertheimer 《The Journal of foot surgery》1987,26(2):95-135
This study is comprised of 71 patients with inversion injuries. The purpose of this article is to present a logical and orderly approach in evaluating these injuries. A comprehensive review of the literature concerning diagnostic techniques and mechanisms of injury related to inversion ankle trauma is presented. Inversion ankle injuries are frequently misdiagnosed as simple sprains when frequently there are other pathologies present. The standard approach of evaluating inversion ankle injuries is often inadequate. 相似文献
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Long- and medium-wavelength cones in the turtle retina participate in complex neural interactions. They are coupled via excitatory pathways to other cones and receive negative feedback inputs from luminosity-type horizontal cells. Little information has been collected on the S- (short-wavelength or blue) cones because they are scarce in the turtle retina and of smaller dimensions compared to the other cone types. In this paper, flash sensitivity action spectra and photoresponses of seven turtle S-cones were measured in the dark-adapted state and during chromatic background illuminations. The desensitizing action of monochromatic background lights was not uniform across the visible spectrum. A red background was most effective in desensitizing the S-cones to long-wavelength stimuli while a blue background light produced its strongest action on the photoresponses elicited by short-wavelength stimuli. The effects of chromatic adaptation on the S-cone action spectrum and on the kinetics of the small-amplitude photoresponses suggested that the S-cones in the turtle retina were involved in complex neural interactions. These included excitatory inputs probably originating in neighboring L-cones and inhibitory long-wavelength inputs probably mediated by L-type horizontal cells. 相似文献
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Stacie E. Perlman M.D. Randolph B. Reinhold M.D. Geoffrey S. Nadzam M.D. 《Surgery for obesity and related diseases》2007,3(4):428-433
BACKGROUND: Little is known about the level of knowledge and comfort with bariatric surgery among family practice physicians. METHODS: Surveys were sent to all family practitioners in Connecticut querying the practice type and knowledge of bariatric surgery. The results were analyzed for the prevalence of opinion. RESULTS: Of 620 surveys sent out, 129 (21%) were completed. Of the 129 respondents, 73% were men, aged 31-79 years, and 92% were board certified, with an average of 19 years' experience. The average body mass index of respondents was 26 kg/m2 (range 16-40). Only 4% of respondents had a body mass index >30 kg/m2. Physicians reported a patient obesity rate of 43%. Of the 129 respondents, 88% believed obesity was difficult to control with diet and exercise alone. Only 6% thought obesity was best controlled surgically. Also, 85% of respondents had referred a patient for gastric bypass, although only 57% were comfortable explaining the procedure. The most common reason for refusal to refer was fear of complications and death. Additionally, 55% correctly listed a body mass index of 40 kg/m2 as qualifying for bariatric surgery without comorbidities; 48% identified the mortality rate of surgery as <1%, with 4% of respondents reporting >10%; and 84% were familiar with gastric bypass, 66% with LapBand, 33% with vertical banded gastroplasty, and 5% with duodenal switch. The respondents believed that nausea was the most common side effect, followed by anemia and fatigue. Finally, 53% believed bowel obstruction was common. CONCLUSIONS: The results of our study have shown that misconceptions about bariatric surgery exist in the family practice community despite the increasing frequency of these procedures. Educational programs need to be designed to assist family practitioners in treating and referring obese patients. 相似文献