• The Korean Journal of Physiology and Pharmacology
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• v.22 no.6
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• pp.721-729
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• 2018

GABAergic control over dopamine (DA) neurons in the substantia nigra is crucial for determining firing rates and patterns. Although GABA activates both $GABA_A$ and $GABA_B$ receptors distributed throughout the somatodendritic tree, it is currently unclear how regional GABA receptors in the soma and dendritic compartments regulate spontaneous firing. Therefore, the objective of this study was to determine actions of regional GABA receptors on spontaneous firing in acutely dissociated DA neurons from the rat using patch-clamp and local GABA-uncaging techniques. Agonists and antagonists experiments showed that activation of either $GABA_A$ receptors or $GABA_B$ receptors in DA neurons is enough to completely abolish spontaneous firing. Local GABA-uncaging along the somatodendritic tree revealed that activation of regional GABA receptors limited within the soma, proximal, or distal dendritic region, can completely suppress spontaneous firing. However, activation of either $GABA_A$ or $GABA_B$ receptor equally suppressed spontaneous firing in the soma, whereas $GABA_B$ receptor inhibited spontaneous firing more strongly than $GABA_A$ receptor in the proximal and distal dendrites. These regional differences of GABA signals between the soma and dendritic compartments could contribute to our understanding of many diverse and complex actions of GABA in midbrain DA neurons.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.1
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• pp.1-7
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• 2015

PURPOSE: The aim of this study was to investigate the effects of distal movement on shoulder muscle activation during diagonal pattern of exercises. METHODS: Seventeen healthy male participants volunteered to participate. Five muscles of shoulder were investigated during standing performance of diagonal shoulder exercises with and without visual trace. Two patterns of the diagonal exercises were used as diagonal 1 flexion and extension (D1F-E), and diagonal 2 flexion and extension (D2F-E). Two way repeated measures analysis of variance was used, which the factor was the presence of distal movement and exercise variations. RESULTS: The average muscle activity values of the lower trapezius and anterior deltoid are higher with the D2F-E, compared to the D1F-E (p<.05). The distal movement effect was observed within included all muscles except the lower trapezius, which the values are significantly greater in exercise with distal movement (P<.05). All significant increase of the muscles during the exercise with distal movement condition showed over 0.9 for the observed power in present study. CONCLUSION: Present result suggested that the diagonal pattern of exercise with distal movement has additional advantages of activating the scapulothoracic muscle as well as glenohumeral muscles. In addition, the D2F-E exercise pattern is effective for activating lower trapezius and anterior deltoid muscles.

• Annals of Clinical Neurophysiology
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• v.4 no.1
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• pp.12-15
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• 2002

Background : Changes in firing pattern and in the recruitment order of single motor unit(MU) have been claimed to be characteristic of central motor lesions, and a reduced firing rate was found in upper motor neuron lesions. But these findings have been rarely studied before in Korea, so we studied initial MU recruitment pattern in stroke patients with hemiparesis. Methods : We studied six patients(3 men and 3 women) whose mean age was $60.6{\pm}7.4$ years. A mean $20.6{\pm}16.2$ months had elapsed since the stroke. To compare the initial MU activation patterns in proximal and distal segments of paretic limb with their contalateral unaffected counterparts, we studied the onset and recruitment intervals in biceps brachii(BB) and first dorsal interossei(FDI) muscles in paretic and healthy arms. In a single muscle we examined from 5 to 10 individual MUs. And in a single motor unit, both the onset interval and the recruitment interval was examined. Results : The mean onset interval in paretic limb was significantly(p<0.05) longer than unaffected limb at proximal and distal location: BB $118.5{\pm}17.8$ msec vs $96.1{\pm}8.3$ msec(n=58); FDI $125.8{\pm}16.7$ msec vs $101.5{\pm}17.2$ msec(n=38). The mean recruitment interval in paretic limb was also significantly(p<0.05) longer than unaffected limb: BB $87.7{\pm}14.9$ msec vs $73.4{\pm}11.5$ msec(n=53); FDI $96.3{\pm}16.4$ msec vs $87.7{\pm}14.1$ msec(n=38). Conclusion : The first recruited MU had a lower baseline firing rate and the second recruited motor unit potential appeared earlier in paretic than in healthy muscles. And these findings may explain one of the reasons for paresis in patients with stroke.

• Korean Journal of Optics and Photonics
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• v.25 no.4
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• pp.200-206
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• 2014

In this paper, using the value theoretically calculated to emit multidirectionally a beam coming into an optical fiber with diameter of $125{\mu}m$, we modeled and produced a cone-shaped structure at the distal end of the fiber. A numerical simulation was performed for an optical fiber tip in which all incident beams were totally reflected and emitted toward the side, as well as for an optical fiber tip from which the beams could be emitted forward and sideways simultaneously. We produced multidirectional-firing optical fiber tips based on the simulation result and model. Laser fabrication of the optical fiber was done by processing a cone-shaped structure at the distal end of an optical fiber with diameter of $125{\mu}m$ using a femtosecond pulsed laser and polishing the processed surface with a $CO_2$ laser. We also conducted an analysis to compare experimental and simulation results.

• The Journal of the Korean dental association
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• v.49 no.11
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• pp.660-669
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• 2011

Er: YAG laser irradiation utilizing the newly developed RCLase side-firing spiral tip was used for the cleansing of root canals following their bio-mechanical preparation with ProTaper Ni-Ti files. The distal and palatal roots of 20 freshly extracted molar teeth were instrumented to size F3 with ProTaper files. In the experimental group (10 teeth) the pulp chamber and the root canals were filled with EDTA 17% and the root canals were lased for 30 s using the Er: YAG laser irradiation at 600 mJ per pulse and a frequency of 12 Hz. In the control group (10 teeth) the root canals were not lased. Scanning electron microscope analysis showed clean wall surfaces of the lased root canals with open dentinal tubules, free of smear layer and debris. In the scanning electron microscope photographs of the walls of the non-lased root canals a considerable amount of debris could be detected. It appears that an efficient cleansing of the root canal system can be achieved by using the Er: YAG laser irradiation with the RCLase Side-firing Spiral Tip following bio-mechanical preparation of the root canal with Ni-Ti Taper files.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.4
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• pp.321-327
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• 2019

Purpose: To evaluate an effect of additional firing process after sintering of monolithic zirconia crown on marginal and internal fit through three-dimensional analysis. Materials and methods: Ten monolithic zirconia crowns were fabricated using titanium abutment model. Monolithic zirconia crowns were designed, milled, and sintered as a control group, and additional firing with coloring was performed as a test group. Three dimensional analysis were performed by using triple-scan protocol, and cross-section analysis on mesio-distal and disto-lingual section was evaluated to measure marginal and internal fitness. Then, three-dimensional surface difference on between two groups was evaluated (${\alpha}=.05$). Results: There was statistically significant difference between the control group ($32.0{\pm}24.3{\mu}m$) and the test group ($17.0{\pm}10.8{\mu}m$) in the mesial axial wall (P < .02) and the control group ($60.2{\pm}24.3{\mu}m$) and the test group ($71.8{\pm}21.5{\mu}m$) in the distal axial wall (P < .01). There was no statistically significant difference at the remaining point. Conclusion: There was no statistical significance on the deviation of inner surface of crown according to firing number, and the results of both group were considered clinically acceptable.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.1
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• pp.120-132
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• 1998

This stusy was to investigate the marginal fitness of porcelain-fused-to- metal crown after succesive firing cycle. Main variables were the degree of marginal curvature of labiocervical margin and the type of alloy. The exaggerated marginal curvature(EMC) was created by additional reduction at the faciocervical wall of the normallized marginal curvature (NMC)-typed ivorine tooth by using milling machine. The difference in the shape was the mid facial margin was placed 2mm apical to cemento- enamel junction in labial surface. Three types of alloy were high noble, noble, and base metal alloy. Test specimens were divided into 8 groups and each group had 8 specimens. Sixty four ceramometal crowns were made totally. Measurement stages were following degassing, opaquing. body porcelain firing, and glazing, and measuring sites were 4. (midmesial, midfacial, middistal, and midlingual). Digital, travelling measuring microscope (0.5 um precision, Olympus. Japan) was used under ${\times}250$ magnification. Within the limitation of this investigation, it was concluded as belows: 1. The pattern of marginal distortion was varied. Degassing stage was not a specific, causative stage that induce most of total marginal distortion during whole procedure fabricating a ceramometal crown. Body firing stage induced discrepancy relatively more than other firing stages. 2. The specimens that were Ni-based alloy and had EMC were distorted persistently following successive fabricating procedures. But marginal openings were decreased after glazing. 3. The release of metal grinding-induced stress was presumed as a cause that induce marginal distortion. 4. The amount of discrepancies of the labial and lingual margins were greater than that of the mesial and distal margin in the specimen that had EMC. 5. Silver-plated die was not enough to resist abrasion during repeated seating of metal copings on the die-holding device.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.10
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• pp.1017-1022
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• 2013

Currently, various optical fiber tips are used to deliver laser beam for endoscopic surgery. In this paper, we demonstrated multidirectional (forward and side) firing optical fiber tip using a femtosecond micromachining and $CO_2$ laser polishing technology. We controlled the edge width of optical fiber tip, by modulating the condition of $CO_2$ laser, to regulate the amount of side and forward emission. The distal end of the optical fiber with core/clad diameter of $400/440{\mu}m$ was microstructured with cone shape by using a femtosecond laser. And then the microstructured optical fiber tip was polished by $CO_2$ laser beam result in smoothing and specular reflection at the surface of the cone structure. Finally, we operated the LightTools simulation and good agreement was generally found between the proposed model and experimental simulation.