• Archives of Reconstructive Microsurgery
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• v.6 no.1
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• pp.9-28
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• 1997

Adequate vascularization is pivotally essential for a successful nerve graft. Theoretically, the immediate vascularization will inhibit fibroblast infiltration and stimulate nerve cell regeneration. In this study, histomorphological and electrophysiological studies were performed to determine if vascularized grafts are functionally superior. In rat model, a 4cm segment of the sciatic nerve was obtained and placed as a non vascularized graft on one side, and as a vascularized graft connected to the inferior gluteal vessels on the opposite side. To determine the compound action potential of the gastrocnemius muscle, electromyography was done after 2, 3 and 4 months. Histomorphologically, the distribution of myelinated nerve fibers and Schwann cell were evaluated after toluidine blue staining, The following resutls were obtained: 1. The electrophysiological studies showed no difference between the nonvascularized and vascularized grafts. 2. Two and three months after grafting, myelinated nerve fibers were more abundant in the vascularized proximal, middle and distal areas in all nerve fibers of varying diameters. 3. In the post-nonvascularized graft 2-month group, a few myelinated nerve fibers were present in the proximal and middle areas, but none distally. In the post-vascularized graft 2 month group, myelinated nerve fibers ranging $2-8{\mu}m$ were present in all three areas. 4. In the post-nonvascularized graft 3 month group, a few myelinated nerve fibers ranging in $2-6{\mu}m$ were present in all three areas, but in the post-vascularized graft 3 month group, many myelinated nerve fibers ranging in $2-10{\mu}m$ were present in all three areas. 5. In the post-graft 4-month group, more myelinated nerve fibers were present in all three areas of the vascularized grafts. However, nerve fibers of less than $2{\mu}m$ in diameter were more abundant in the non vascularized grafts. 6. Schwann cells were more abundant in the proximal, middle and distal areas of the post-vascularized 2, 3 and 4-month grafts. Based on these findings, the immediate restoration of circulation in vascularized nerve grafts allows for the increased number of surviving Schwann cells, rapid healing of the axon and myelin sheath changes which occur during Wallerian degeneration, and thus is able to stimulate a morphologically optimal regeneration.

• Archives of Reconstructive Microsurgery
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• v.6 no.1
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• pp.29-38
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• 1997

A peripheral nerve when approximation of the ends imparts tension at the anastomosis and with a relatively long segment defect after excision of neuroma and neurofibroma cannnot be repaired by early primary suture. The one of the optimistic reconstruction method of severed peripheral nerves is to restore tension-free continuity at the repair site putting an autogenous nerve graft into the neural gap despite of ancipating motor or sensory deficit of the donor nerve area. To overcome the deficit of the autogenous nerve graft, several other conduits supplying a metabolically active environment which is able to support axon regeneration and progression, providing protection against scar invasion, and guiding the regrowing axons to the distal stump of the nerve have been studied. An author have used ipsilateral femoral vein, ipsilateral femoral vein filled with fresh thigh muscle, and autogenous sciatic nerve for the sciatic nerve defect of around 10 mm in length to observe the regeneration pattern in rat by light and electron microscopy. The results were as follows. 1. Light microscopically regeneration pattern of nerve fibers in the autogenous graft group was more abundant than vein graft and vein filled with muscle group. 2. On ultrastructural findings, the proxial end of the graft in various groups showed similar regenerating features of the axons, myelin sheaths, and Schwann cells. The fascicular arrangement of the myelinated and unmyelinated fibers was same regardless of the type of conduits. There were more or less increasing tendency in the number and the diameter of myelinated fibers correlated with the regeneration time. 3. In the middle of the graft, myelinated nerve fibers of vein filled with muscle group were more in number and myelin sheath was thinner than in the venous graft, but the number of regenerating axons in autogenous nerve graft was superior to that in both groups of the graft. The amount of collagen fibrils and amorphous materials in the endoneurial space was increased to elapsed time. 4. There was no difference in regenerating patterns of the nerve fibers of distal end of the graft. The size and shape of the myelinated nerve fbers were more different than that of proximal and middle portion of the graft. From the above results, the degree of myelination and regenerating activity in autogenous nerve is more effective and active in other types of the graft and there were no morphological differences in either ends of the graft regardless of regeneration time.

• Korean Journal of Veterinary Research
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• v.9 no.1
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• pp.1-9
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• 1969

The experimental studies were performed to observe the characteristics of the myelinated nerve fibers of the tradiaphragmatic branches of phrenic nerves in dog In the work to be reported five mixed breed Korean dog were used, they were one year old and he body eights were about 12 Kgm. in average with healthy conditions. The specimens (nerve) were taken at the point of 1.5 cm posterior part from the left and right phrenic nerves entrance to the diaphragm, and the dorso-lateral and dorso-medial branches of phrenic nerves vere also, taken at the point of 0.5 cm distal part from their branching portion. The specimens were fixed for 24 hrs. in Flemming's solution, and embedded in paraffin. The paraffin section. were cut at 6 microns and stained with Walter's modification of Weigert-pal method for the myelinated fibers. Microphotographs were taken and enlarged into 750 times of the actual size, and the diameter of the photographic images of the myelinated fibers were measured by the scale on the transparent Percepex Plate. The following conclusions were made: 1. The percentage of distribution of the several intradiaphragmatic branches of phrenic nerves were as follows. Ventral branches were 34.97%, lateral branches were 37.90%, dorsal branches were 27.13%, and the dorsal branches were branched again into dorso-lateral branches(54.22%) and dorso-medial branches (45. 78%). 2. The mean value and S.D. of the total numbers of the myelinated nerve fibers at the left ventral branches were $490.80{\pm}12$, and at the right ventral branches were $486.6{\pm}13$. Total average cross sectional area on the left ventral branches were 38,000. $6{\pm}136{\mu}^2$, and the right ventral branches were $37,150.2{\pm}1.782{\mu}^2$. 3. The mean value and S.D. of the total numbers of the myelinated nerve fibers at the left lateral branches were $533.8{\pm}8$, and at the right lateral branches were $525.6{\pm}7$. Total average cross sectional area of the left lateral branches were $41,582{\pm}1,170{\mu}^2$, and the right lateral branches were $40,454.8{\pm}812{\mu}^2$. 4. The mean value and S.D. of the total numbers of the myelinated nerve fibers at the left dorsal branches were $378.2{\pm}14$, and at the right dorsal branches were $380.2{\pm}8$. Total average cross sectional area of the left dorsal branches were $27,771{\pm}1,256{\mu}^2$, and the right dorsal branches were $27,507.2{\pm}645{\mu}^2$. 5. The mean value and S.D. of the total numbers of the myelinated fibers at the left dorso-lateral branches were $205.4{\pm}15$, and at the right dorso-lateral branches were $210.6{\pm}17$. Total average cross sectional area of the left dorso lateral branches were $15,354. 8{\pm}1,519{\mu}^2$, and the right dorsal branches were $15,887{\pm}1,297{\mu}^2$. 6. The mean value and S.D. of the total numbers of the myelinated nerve fibers at the left dorso-medial branches were $175{\pm}14$, and at the right dorso-medial branches were $176.2{\pm}17$. Total average cross sectional area of the left dorso-medial branches were $13,037.4{\pm}944{\mu}^2$, and at the right dorso-medial branches were, $13,103{\pm}1,373{\mu}^2$. 7. The highest frequent distribution of the intradiaphragmatic branches of phrenic nerves were found in the $10-12{\mu}^2$ groups, and they were almost 30% of the total groups. 8. The largest fibers diameter were in the $14-16{\mu}^2$ groups, and these were shown the lowest frequent distribution. 9. The largest cross sectional area of the intradiaphragmatic branches of phrenic nerves were found in the $10-12{\mu}^2$ groups. 10. All of the intradiaphragmatic branches of phrenic nerves were unimodal which has a peak in the $10-12{\mu}^2$ groups.

• Journal of Korean Biological Nursing Science
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• v.8 no.1
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• pp.39-48
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• 2006

Purpose: To see the effects of capsaicin on the peripheral nerve damage of intervibrissal fur in mature rats, Method: 24 female mature rats($200{\sim}250g$) are divided to 3 groups and compared with each other. Immunofluorescence dye using CGRP and PGP antibodies was performed and 8 weeks after administration of capsaicin with control group. Result: The immunopositive reaction against PGP and CGRP was reduced by the damage of epidermal and dermal endings in unmyelinated sheath and thin myelinated sheath and the group after 8weeks showed distinct positive reaction of PGP and CGRP than the group after 4 weeks which means the recover of nerves. Conclusion: As a result, capsaicin influenced on pain-related neurotransmitter like CGRP when administerd to mature rats and even though it caused the damages on unmyelinated sheath and thin myelinated sheath, the damaged nerves recovered after 8 weeks. Also the research about sensory nerve endings scattered over middle dermal and deep epidermal layers such as lanceolate, merkel reticular, Ruffini endings should be studied when the research of the inner conical body is performed. Further studies are necessary about the toxicity and effect of capsaicin on the peripheral nerve endings.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.1002-1009
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• 2010

I made the axon to the electrical transmission model and then constructed electrical equivalent model using Kirhhoff's current law and voltage law in this paper. I calculated various axon parameters in order to analyze the electrical potential hehavior versus minute distance chang of axon. The transmission velocity of unmyelinated nerve is proportional to square root of axon diameter, while that of myelinated nerve is directly proportional to its diameter. Because the transmission of myelin sheath is independent of voltage unlike unmyelinated sheath, the Hodgkin-Huxley model across the membrane is not so precise.

• Applied Microscopy
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• v.36 no.2
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• pp.131-140
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• 2006

Neurofascin, one of the members of L1CAM, has been known to have some important roles during the development of nerve fibers. In order to investigate the role of neurofascin associated with the myelination of peripheral nerves, the localization of neurofascin in myelinated rat sciatic nerve fibers was studied with the immuno-fluorescence and immune-electron microscopy and the results are as follows; 1. According to the myelination is going on, neurofascin localization was dramatically changed in the sciatic nerve fibers. 2. In the myelinated fibers, neurofascin was weakly localized along the axolemma at the node of Ranvier. 3. Neurofascin was also apparantly localized at the non-compact area of Schwann cell membrane such as paranodal loop, Schmidt-Lantermann incisure, inner & outer mesaxons in the myelinated fibers. From the above results, neurofascin is likely to have a role to sustain the ideal gap of apposing membranes of Schwann cell, so it may enable to materials transport in the myelin sheath.

• Journal of Veterinary Clinics
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• v.19 no.3
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• pp.316-321
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• 2002

The purpose of this study was to examine the effect of Ga-As(Gallium-Arsenide, wave length; 904 nm) infrared laser irradiation on healing of the experimentally crush injured rat sciatic nerves. The bilateral sciatic nerves of 43 adult male Sprague-Dawley rats were compressed surgically with a straight hemostat (1 mm width). The right legs of all the rats were irradiated using a 27 mW Ga-As infrared laser (laser irradiated group). The radiation procedure was administered for 3 minutes every day for 1, 3, 5, and 7 weeks in each group. Left legs were not irradiated and served as the control group. The numbers of total myelinated axon and degenerated myelin in the sciatic nerves of bilateral legs were measured and analyzed with mage analysis system in order to make a morphological analysis of the effect of the Ga-As infrared laser on injured nerves. Total number of myelinated axons was increased with time interval, especially in the 1, 3. and 5 week of irradiated group. Conversely, the number of degenerated myelin was decreased with time interval, especially in the irradiated group. The effects in the irradiated group were more pronounced than those of the control group. In conclusion, the Ga-As infrared laser irradiation is a useful adjuvant therapy to the regeneration of the peripheral nerve injury.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.5
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• pp.360-365
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• 2010

Introduction: Mammalian tooth pulp is densely innervated by sensory nerves that are mostly C fibers and A delta fibers. However, there is evidence suggesting that many unmyelinated axons in the pulp are in fact parent meylinated axons. Immunohistochemical staining for neurofilament protein 200 kDa (NFP200) was performed to identify the demyelinated but parent myelinated axons. Materials and Methods: The pulp was removed from healthy premolars and 3rd molars extracted from juveniles and adults undergoing orthodontic treatment, and immunohistochemical staining were applied with NPF200 antibodies, which specifically dye myelinated axons. The specimens underwent an electron microscopy examination with diaminobenzidine (DAB) immunostaining after observation and analysis by fluorescence and confocal laser scanning microscopy. Results: The NPF200 immuno-positive axons in the radicular pulp areas were observed as bundles of many nerve fibers. Many small bundles were formed with fewer axons when firing to the coronal pulp areas and then reachrd a different direction. In the radicular pulp, unmyelinated axons and myelinated axons were present together. However, in the coronal pulp, unmyelinated axons were most common and NFP200 immuno-positive unmyelinated axons with a larger diameter than those in the radicular pulp were observed more frequently. On the other hand, most of the immuno-positive unmyelinated fibers were similar in size to that of typically well-known unmyelinated fibers. Conclusion: Myelinated fibers innervated to the dental pulp maintain their myelins in the radicular portion, but these fibers lost myelins in the coronal portion. After the loss of myelin, the size of the axoplasm also decreased.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.1
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• pp.1-16
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• 2004

The use of artificial nerve conduit containing viable Schwann cells is one of the most promising strategies to repair the peripheral nerve injury. To fabricate an effective nerve conduit whose microstructure and internal environment are more favorable in the nerve regeneration than existing ones, a new three-dimensional Schwann cell culture technique using $Matrigel^{(R)}$. and dorsal root ganglion (DRG) was developed. Nerve conduit of three-dimensionally arranged Schwann cells was fabricated using direct seeding of freshly harvested DRG into a $Matrigel^{(R)}$ filled silicone tube (I.D. 1.98 mm, 14 mm length) and in vitro rafting culture for 2 weeks. The nerve regeneration efficacy of three-dimensionally cultured Schwann cell conduit (3D conduit group, n=6) was assessed using SD rat sciatic nerve defect of 10 mm, and compared with that of silicone conduit filled with $Matrigel^{(R)}$ and Schwann cells prepared from the conventional plain culture method (2D conduit group, n=6). After 12 weeks, sciatic function was evaluated with sciatic function index (SFI) and gait analysis, and histomorphology of nerve conduit and the innervated tissues of sciatic nerve were examined using image analyzer and electromicroscopic methods. The SFI and ankle stance angle (ASA) in the functional evaluation were $-60.1{\pm}13.9$, $37.9^{\circ}{\pm}5.4^{\circ}$ in 3D conduit group (n=5) and $-87.0{\pm}12.9$, $32.2^{\circ}{\pm}4.8^{\circ}$ in 2D conduit group (n=4), respectively. And the myelinated axon was $44.91%{\pm}0.13%$ in 3D conduit group and $13.05%{\pm}1.95%$ in 2D conduit group to the sham group. In the TEM study, 3D conduit group showed more abundant myelinated nerve fibers with well organized and thickened extracellular collagen than 2D conduit group, and gastrocnemius muscle and biceps femoris tendon in 3D conduit group were less atrophied and showed decreased fibrosis with less fatty infiltration than 2D conduit group. In conclusion, new three-dimensional Schwann cell culture technique was established, and nerve conduit fabricated using this technique showed much improved nerve regeneration capacity than the silicone tube filled with $Matrigel^{(R)}$ and Schwann cells prepared from the conventional plain culture method.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.4
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• pp.295-307
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• 2006

Styela clava, called non-native tunicate or sea squirt, is habitat which include bays and harbors in Korea and several sites in the sea faced world. We fabricate cellulose membrane nerve conduit (CMNC) from this native sea squirt skin, and evaluate the capacity of promoting peripheral nerve regeneration in the rat sciatic nerve defect model. After processing the pure cellulose membrane from the sea squirt skin as we already published before, CMNC was designed as a non-tubular sheet with 14 mm length and 4 mm width. Total eleven male Spraque-Dawley rats (12 weeks, weighing 250 to 300g) were divided into sham group (n=2), silicone tube grafted control group (n=3) and experimental group (n=6). Each CMNC grafted nerve was evaluated after 4, 8 and 12 weeks in the experimental group, and after 12 weeks, sciatic function was evaluated with sciatic function index (SFI) and gait analysis, and histomorphology of nerve conduit and the innervated tissues of sciatic nerve were all examined using image analyzer and electromicroscopic methods in the all groups. The regenerated axon and nerve sheath were found only in the inner surface of the CMNC after 4 weeks and became more thicker after 8 and 12 weeks. In the TEM study, CMNC grafted group showed more abundant organized myelinated nerve fibers with thickened extracellular matrix than silicone conduit grafted group after 12 weeks. The sciatic function index (SFI) and ankle stance angle (ASA) in the functional evaluation were $-47.2{\pm}3.9$, $35.5^{\circ}{\pm}4.9^{\circ}$ in CMNC grafted group (n=2) and $-80.4{\pm}7.4$, $29.2^{\circ}{\pm}5.3^{\circ}$ in silicone conduit grafted group (n=3), respectively. And the myelinated axon was 41.59% in CMNC group and 9.51% in silicone conduit group to the sham group. The development of a bioactive CMNC to replace autogenous nerve grafts offers a potential and available approach to improved peripheral nerve regeneration. As we already published before, small peptide fragment derived from the basement membrane matrix proteins of squirt skin, which is a kind of anchoring protein composed of glycocalyx, induced the effective axonal regeneration with rapid growth of Schwann cells beneath the inner surface of CMNC. So the possibilities of clinical application as a peripheral nerve regeneration will be able to be suggested.