• 대한의용생체공학회:의공학회지
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• 제38권4호
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• pp.175-182
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• 2017

Microcurrent electrical stimulation(MES) has been used to accelerate recovery of atrophied skeletal muscle. However, convincing stimulation parameters for suppressing muscle atrophy due to injured sciatic nerve remains unclear. The objective of this study was to investigate the effective intensity of MES on restraining muscle atrophy with rat model underwent sciatic nerve injury(SNI). Twenty-5-week-old Sprague Dawley male rats were equally assigned to five groups : Control group(Control, CON, n = 4), Denervation group(Denervation, D, n = 4), Denervation with MES of $22{\mu}A$ group(Denervation + $22{\mu}A$, D+22, n = 4), Denervation with MES of $100{\mu}A$ group (Denervation + $100{\mu}A$, D+100 n = 4), Denervation with MES of $400{\mu}A$ group(Denervation + $400{\mu}A$, D+400, n = 4). To induce muscle atrophy, all rats in the D, D+22, D+100, and D+400 groups, were subjected to sciatic nerve injury on their right hindlimb and allowed to have 1 week of resting period. Following this period, rats underwent daily MES(60 min/ a day, 5times/1week) for 4 weeks. After that, we investigate morphological changes in muscle volume by using in vivo micro-computed tomography at week 0, 1, 3 and 5. After 5 weeks, the muscle volume had the highest value in D+400 group, and also noticeably increased in D+100 group compared to it in D group. The results of this study imply that MES with current intensities between $100-400{\mu}A$ can suppress muscle atrophy effectively.

• Journal of Periodontal and Implant Science
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• 제46권5호
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• pp.303-319
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• 2016

Purpose: The purpose of this animal study was to perform a 3-dimensional micro-computed tomography (micro-CT) analysis in order to investigate the influence of root surface distance to the alveolar bone and the periodontal ligament on periodontal wound healing after a guided tissue regeneration (GTR) procedure. Methods: Three adult Sus scrofa domesticus specimens were used. The study sample included 6 teeth, corresponding to 2 third mandibular incisors from each animal. After coronectomy, a circumferential bone defect was created in each tooth by means of calibrated piezoelectric inserts. The experimental defects had depths of 3 mm, 5 mm, 7 mm, 9 mm, and 11 mm, with a constant width of 2 mm. One tooth with no defect was used as a control. The defects were covered with a bioresorbable membrane and protected with a flap. After 6 months, the animals were euthanised and tissue blocks were harvested and preserved for micro-CT analysis. Results: New alveolar bone was consistently present in all experimental defects. Signs of root resorption were observed in all samples, with the extent of resorption directly correlated to the vertical extent of the defect; the medial third of the root was the most commonly affected area. Signs of ankylosis were recorded in the defects that were 3 mm and 7 mm in depth. Density and other indicators of bone quality decreased with increasing defect depth. Conclusions: After a GTR procedure, the periodontal ligament and the alveolar bone appeared to compete in periodontal wound healing. Moreover, the observed decrease in bone quality indicators suggests that intrabony defects beyond a critical size cannot be regenerated. This finding may be relevant for the clinical application of periodontal regeneration, since it implies that GTR has a dimensional limit.

• 생명과학회지
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• 제20권8호
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• pp.1207-1213
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• 2010

본 연구의 목적은 랫드의 두개결손부 모델에서 돼지 해면질골을 지지체로 사용했을 때의 효과를 평가해보고자 하였다. 임계결손부의 형성은 30마리의 수컷 Sprague-Dawley 랫드에서 실시하였으며 동물들은 임계결손군(CD group, n=10), 베타 삼인산칼슘군(BT group, n=10) 및 돼지 해면질골군(PCB group, n=10)으로 나누었다. 각각의 결손부위는 피브린 글루와 혼합시킨 베타 삼인산칼슘 또는 돼지 해면질골로 채워졌으며 CD군은 결손부위에 이식재를 이식하지 않았다. 모든 랫드들은 골이식 수술 8주 후에 희생되었으며 희생 후 육안검사, 단순 방사선촬영, micro-CT 촬영 및 조직검사를 통해 골형성 정도를 평가하였다. 결과에서 골결손부의 치유는 CD군에서 가장 낮았으며 PCB군에서는 유의성 있는 새로운 골형성을 확인할 수 있었다. 또한 방사선촬영 결과, 조직학적 평가 및 micro CT 촬영 결과에서 골이식 시 돼지 해면질골이 베타 삼인산칼슘보다 새로운 골형성에 있어 더욱 효과적임을 관찰할 수 있었다.

• Tuberculosis and Respiratory Diseases
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• 제73권1호
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• pp.22-31
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• 2012

Background: Oxidation plays an important role in acute lung injury. This study was conducted in order to elucidate the effect of repetitive post-treatment of N-acetylcysteine (NAC) in lipopolysaccaride (LPS)-induced acute lung injury (ALI) of rats. Methods: Six-week-old male Sprague-Dawley rats were divided into 4 groups. LPS (Escherichia coli 5 mg/kg) was administered intravenously via the tail vein. NAC (20 mg/kg) was injected intraperitoneally 3, 6, and 12 hours after LPS injection. Broncho-alveolar lavage fluid (BALF) and lung tissues were obtained to evaluate the ALI at 24 hours after LPS injection. The concentration of tumor necrosis factor ${\alpha}$ (TNF-${\alpha}$) and interleukin $1{\beta}$ (IL-$1{\beta}$) were measured in BALF. Nuclear factor ${\kappa}B$ (NF-${\kappa}B$), lipid peroxidation (LPO), and myeloperoxidase (MPO) were measured using lung tissues. Micro-computed tomography (micro-CT) images were examined in each group at 72 hours apart from the main experiments in order to observe the delayed effects of NAC. Results: TNF-${\alpha}$ and IL-$1{\beta}$ concentration in BALF were not different between LPS and NAC treatment groups. The concentration of LPO in NAC treatment group was significantly lower than that of LPS group ($5.5{\pm}2.8$ nmol/mL vs. $16.5{\pm}1.6$ nmol/mL) (p=0.001). The activity of MPO in NAC treatment group was significantly lower than that of LPS group ($6.4{\pm}1.8$ unit/g vs. $11.2{\pm}6.3$ unit/g, tissue) (p<0.048). The concentration of NF-${\kappa}B$ in NAC treatment group was significantly lower than that of LPS group ($0.3{\pm}0.1\;ng/{\mu}L$ vs. $0.4{\pm}0.2\;ng/{\mu}L$) (p=0.0001). Micro-CT showed less extent of lung injury in NAC treatment than LPS group. Conclusion: After induction of ALI with lipopolysaccharide, the therapeutic administration of NAC partially attenuated the extent of ALI through the inhibition of NF-${\kappa}B$ activation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제50권1호
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• pp.13-26
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• 2024

Objectives: The aim of this study was to perform a comparative analysis of the ultrastructural and chemical composition of sialoliths, tonsilloliths, and antroliths and to describe their growth pattern. Materials and Methods: We obtained 19 specimens from 18 patients and classified the specimens into three groups: sialolith (A), tonsillolith (B), and antrolith (C). The peripheral, middle, and core regions of the specimens were examined in detail by histology, micro-computed tomography (micro-CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, and transmission electron microscopy (TEM). Results: In the micro-CT, group A showed alternating radiodense and radiolucent layers, while group B had a homogeneous structure. Group C specimens revealed a compact homogeneous structure. Histopathologically, group A showed a laminated, teardrop-shaped, globular structure. Group B demonstrated degrees of immature calcification of organic and inorganic materials. In group C, the lesion was not encapsulated and showed a homogeneous lamellar bone structure. SEM revealed that group A showed distinct three layers: a peripheral multilayer zone, intermediate compact zone, and the central nidus area; groups B and C did not show these layers. The main elemental components of sialoliths were O, C, Ca, N, Cu, P, Zn, Si, Zr, F, Na, and Mg. In group B, a small amount of Fe was found in the peripheral region. Group C had a shorter component list: Ca, C, O, P, F, N, Si, Na, and Mg. TEM analysis of group A showed globular structures undergoing intra-vesicular calcification. In group B, bacteria were present in the middle layer. In the outer layer of the group C antrolith, an osteoblastic rimming was observed. Conclusion: Sialoliths had distinct three layers: a peripheral multilayer zone, an intermediate compact zone and the central nidus area, while the tonsillolith and antrolith specimens lacked distinct layers and a core.

• Restorative Dentistry and Endodontics
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• 제36권3호
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• pp.231-237
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• 2011

연구목적: 본 연구에서는 micro CT를 사용하여 SS K-file, Profile, LightSpeed로 #25부터 #40 크기까지 근관을 형성할 때 근단부 근관 형태의 연속되는 변화를 평가하였다. 연구 재료 및 방법: 30개 하악 대구치의 근심 근관을 ProFile, LightSpeed와 SS K-file로 #25번에서 #40번까지 순차적으로 근관 형성하였고, 매 단계 확대 후 micro CT를 시행하였다. 치근단 1, 2, 3, 5 mm 에서 근관 중심 변위와 삭제되지 않은 단면의 비율을 측정하여 'repeated nested design' 분석방법과 Mann-Whitney test로 유의 수준 p = 0.05에서 검정하였다. 결과: SS K-file군에서 #30 이상 근관 형성 후 유의할 만한 근관 중심 변위가 증가하였고, 근관 형성 과정 어느 단계에서도 삭제되지 않은 면적의 비율이 유의성 있게 감소되지 않았다. ProFile군에서는 치근단 1, 2 mm에서 #40 file로 근관 형성 후 근관 중심 변위가 크게 증가하였고, 치근단 1 mm에서 #35 크기로 근관 형성한 후에 삭제되지 않은 면적의 비율이 유의성 있게 감소하였다. LightSpeed군에서는 급격한 근관 중심 변위를 관찰할 수 없었고, 근관 중심 변위가 ProFile군보다 적게 관찰되었다. 결론: SS K-file, Profile, LightSpeed에서 형성되는 근관의 변이 정도는 근단부 근관 형성 크기에 따라 다르게 나타났다.

• 한방재활의학과학회지
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• 제24권1호
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• pp.31-45
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• 2014

Objectives This study intends to clarify how Leejung-tang (here in after reffered to LJT) affect Wistar Rat whose osteoarthritis was induced by MIA. Methods Osteoarthritis was induced into rat by injecting MIA in its knee joint. Rats are divided into a total of 4 groups (n=6). Normal group are not treated at all without inducing osteoarthritis whereas control group were induced for osteoarthritis by MIA and oral medicated with 2 ml of physiological saline per day. Positive comparison group (Indomethacin) was injected with MIA and after 7 days, 2 mg/kg of Indomethacin was medicated. Experimental group (LJT) was injected with MIA and after 7 days that was medicated with 23 mg/kg of LJT. Indomethacin and LJT were oral medicated for each substance a total of 4 weeks with one time per day. After experiments (from 1 week after injection of MIA to 4 weeks elapsed), Hind paw weight bearing ability, Functions of liver and kidney, Serum prostaglandin $E_2$, TNF-${\alpha}$, IL-1${\beta}$, IL-6, Osteocalcin, TIMP-1, MMP-9, LTB4 and amount of cartilage were measured and histopathological variations for knee joint structures were observed. Results 1) Hind paw weight bearing ability of LJT administration group was increased but there was no statistical significance. 2) Functions of liver and kidney were not affected. 3) Serum prostaglandin $E_2$, IL-1${\beta}$, Osteocalcin, MMP-9 were significantly decreased and TNF-$\alpha$, IL-6, TIMP-1, LTB4 were also decreased but there were no statistical significance. 4) In H&E staining and Safranin-O staining, there were small histopathological changes in LJT administration group than control group. 5) In micro CT (computed tomography)-arthrography, cartilage destruction was more suppressed in LJT administration group than control group. Conclusions Based on all results mentioned above, Leejung-tang (LJT) is believed to be meaningful for suppressing the progress of osteoarthritis and its treatments because of its anti-inflammatory effects and alleviation of pain with histopathological effective efficacy.

• Journal of Periodontal and Implant Science
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• 제47권2호
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• pp.86-95
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• 2017

Purpose: The aim of this study was to determine the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded synthetic bone substitute on implants that were simultaneously placed with sinus augmentation in rabbits. Methods: In this study, a circular access window was prepared in the maxillary sinus of rabbits (n=5) for a bone graft around an implant (${\varnothing}3{\times}6mm$) that was simultaneously placed anterior to the window. Synthetic bone substitute loaded with rhBMP-2 was placed on one side of the sinus to form the experimental group, and saline-soaked synthetic bone substitute was placed on the other side of the sinus to form the control group. After 4 weeks, sections were obtained for analysis by micro-computed tomography and histology. Results: Volumetric analysis showed that the median amount of newly formed bone was significantly greater in the BMP group than in the control group ($51.6mm^3$ and $46.6mm^3$, respectively; P=0.019). In the histometric analysis, the osseointegration height was also significantly greater in the BMP group at the medial surface of the implant (5.2 mm and 4.3 mm, respectively; P=0.037). Conclusions: In conclusion, an implant simultaneously placed with sinus augmentation using rhBMP-2-loaded synthetic bone substitute can be successfully osseointegrated, even when only a limited bone height is available during the early stage of healing.

• Geomechanics and Engineering
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• 제13권1호
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• pp.141-159
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• 2017

A pick cutter is a rock-cutting tool used in partial-face excavation machines such as roadheaders, and its quality is a key element influencing the excavation performance and efficiency of such machines. In this study, pick cutters with hardfacing deposits applied to a tungsten carbide insert were made with aim of increasing their durability and wear resistance. They were field-tested by being installed in a roadheader and compared with conventional pick cutters under the same excavation conditions for 24 hours. The hardfaced pick cutters showed much smaller weight loss after excavation, and therefore better excavation performance, than the conventional pick cutters. In particular, the damage to and detachment (loss) of tungsten carbide inserts was minimal in the hardfaced pick cutters. A detailed inspection using scanning electron microscope-energy dispersive X-ray spectrometry and three-dimensional X-ray computed tomography scanning revealed no macro- or micro-cracks in the pick cutters. The reason for the absence of cracks may be that the heads of pick cutters are mechanically worn after the tungsten carbide inserts have been worn and damaged. However, scanning revealed the presence of voids between tungsten carbide inserts and pick cutter heads. This discovery of voids indicates the need to improve production processes in order to guarantee a higher quality of pick cutters.

• Journal of Periodontal and Implant Science
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• 제45권2호
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• pp.62-68
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• 2015

Purpose: The goal of this study was to investigate the histomorphometric characteristics of the healing process of microcracks in the cortical bone after the installation of mini-implants (MIs). Methods: Self-drilling MIs were inserted into the tibial diaphysis of twelve adult male New Zealand rabbits. Four MIs per rabbit were placed randomly. The animals were divided into four groups according to the length of the healing period: group A was sacrificed immediately, group B was sacrificed after one week, group C was sacrificed after two weeks, and group D was sacrificed after four weeks. Cortical bone thickness was measured using micro-computed tomography, and histomorphometric analyses of the cumulative length of the microcracks (CLCr) and the total number of microcracks (NCr) were performed using hematoxylin and eosin staining. Results: The microcracks were radially and concentrically aligned in the peri-MI bone. The CLCr decreased significantly one week after the surgery, mainly due to healing of the concentrically aligned microcracks. The CLCr showed another significant decrease from two weeks after the surgery to four weeks after the surgery, mainly reflecting healing of the radially aligned microcracks. A statistically significant decrease in the NCr occurred as the microcracks healed from zero weeks to two weeks. However, no significant difference in the NCr was found between groups C and D. Conclusions: In order to improve the primary stability of MIs, delayed loading and a healing period of a certain length are recommended to ensure the optimal healing of microcracks and bone remodeling.