• Molecules and Cells
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• 제43권9호
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• pp.774-783
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• 2020

The lung has a vital function in gas exchange between the blood and the external atmosphere. It also has a critical role in the immune defense against external pathogens and environmental factors. While the lung is classified as a relatively quiescent organ with little homeostatic turnover, it shows robust regenerative capacity in response to injury, mediated by the resident stem/progenitor cells. During regeneration, regionally distinct epithelial cell populations with specific functions are generated from several different types of stem/progenitor cells localized within four histologically distinguished regions: trachea, bronchi, bronchioles, and alveoli. WNT signaling is one of the key signaling pathways involved in regulating many types of stem/progenitor cells in various organs. In addition to its developmental role in the embryonic and fetal lung, WNT signaling is critical for lung homeostasis and regeneration. In this minireview, we summarize and discuss recent advances in the understanding of the role of WNT signaling in lung regeneration with an emphasis on stem/progenitor cells.

• 대한관절경학회지
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• 제13권3호
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• pp.189-192
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• 2009

Although the articular cartilage is only a few milimiters thick, it has surprising stiffness to compression, exceptional ability to distribute load minimizing peak stress on subchondral bone and great durability. In many instances, it help to preserve normal joint function for more than 80 years. Varying in thickness, cell density, matrix composition, mechanical properties even within the same joint, it provides low-friction and pain free-motion. However, it lacks a blood or lymphatic supply and neurological elements are absent. It shows limited healing potential because of poor regenerative capacity.

• Biomaterials and Biomechanics in Bioengineering
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• 제2권2호
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• pp.61-69
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• 2015

Undifferentiated stem cells are being studied to obtain information on the therapeutic potential of isolates that are produced. Dental Pulp Stem Ccell (DPSC) may provide an abundant supply of highly proliferative, multipotent Mesenchymal Stem Cells (MSC), which are now known to be capable of regenerating a variety of human tissues including bone and other dental structures. Many factors influence DPSC quality and quantity, including the specific methods used to isolate, collect, concentrate, and store these isolates once they are removed. Ancillary factors, such as the choice of media, the selection of early versus late passage cells, and cryopreservation techniques may also influence the differentiation potential and proliferative capacity of DPSC isolates. This literature review concludes that due to the delicate nature of DPSC, more research is needed for dental researchers and clinicians to more fully explore the feasibility and potential for isolating and culturing DPSCs extracted from adult human teeth in order to provide more accurate and informed advice for this newly developing field of regenerative medicine.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• 제56권12호
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• pp.749-753
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• 2013

Basically stem cells have characteristics of multi-potency, differentiation into multiple tissue types, and self-renew through proliferation. Recent advances in stem cell biology can make identifying the stem-cell like cells in various mammalian tissues. Stem cells in various tissues can restore damaged tissue. Stem cells from the adult nervous system proliferate to form clonal floating colonies called spheres in vitro, and recent studies have demonstrated sphere formation by cells in the tympanic membrane, vestibular system, spiral ganglion, and partly in the organ of Corti. The presence of stem cells in the ear raises the possibilities for the regeneration of the tympanic membrane & inner ear hair cells & neurons. But the gradual loss of stem cells postnatally in the organ of Corti may correlate with the loss of regenerative capacity and limited hearing restoration. Future strategies using endogenous stem cells in the ear can be the another treatment modality for the patients with intractable inner ear diseases.

• Journal of Periodontal and Implant Science
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• 제25권2호
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• pp.341-356
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• 1995

The purpose of this study was to evaluate the effect of demineralized freeze dried bone and demineralized bone gel with guided tissue regeneration treatment around titanium implants with dehisced bony defects and also evaluate space maintaining capacity of demineralized bone gel type and DFDB powder type under e-PTFE membrane. In 3 Beagle dogs, mandibular premolar was extracted and four peri-implant osteotomies were formed for dehiscence. After insertion of implants, the four peri-implant defects were treated as follows. 1) In control group. no graft material and barrier membrane were applied. 2) In experimental group.1, the site was covered only with the e-PTFE membrane. 3) In experimental group 2,received DFDB powder and covered by the e-PTFE membrane. 4) In experimental group 3, demineralized bone gel and e-PTFE membrane were used. By random selection, animals were sacrificed at 4, 8, 12 weeks. The block sectioned specimens were prepared for decalcified histologic evaluation(hematoxylin and eosin staining) and undecalcified histologic evahiation(Von Kossa's and toluidine blue staining) with light microscopy. The results of this study were as follows. 1) In control group, there was a little new bone formation and connective tissue was completely filled in the defect area. 2) Experimental group 1 showed lesser quantity of bone formation as compared to the bone grafted group. Thin vertical growth of new bone formation around implant fixture was shown. 3) Experimental group 2 showed thick bucco-lingual growth of new bone formation and grafted bone particles were almost resorbed in 12 week group. 4) In experimental group 3, most grafted bone particles were not resorbed in 12 week group and thick bucco-lingual bone formation was shown in dehisced defect base area. 5) There was no remarkable differences in space making capacity and new bone formation procedure between demineralized freeze-dried bone powder type and demineralized bone gel type.

• Journal of Periodontal and Implant Science
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• 제25권3호
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• pp.603-613
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• 1995

The purpose of this investigation was to evaluate on the biodegradability, biocompatibility and tissue regenerative capacity of synthetic bioabsorbable membranes in beagle dogs. For animal study, 9 adult beagle dogs were used to examination, on the surgical implantation of membranes and histological analysis. In each animal, the 3rd and 4th premolars of the both sides of the mandible were selected as test teeth. Two types of bioresorbable membranes including "Guidor membrane", "S-membranes" were used to examining for biological activity, and also Gore-tex membranes was used for positive control. Surgically created defects were made in 2 premolars of both sides of the mandible at $3{\times}4mm^2$ in size and tested membranes were implanted in the defected area. A plaque control regimen was instituted with daily tooth brushing with a 0.1% chlorhexidine digluconate during experimental periods. All the experimental animals were sacrificed after 2, 4, and 8 weeks from surgery and undecalcified slides were prepared using the "sawing and grinding" technique described by Donath and Breuner". In biodegradability, all the membranes were started their biodegradation from two weeks after implantation and gradually demolished of their frame morphology from eight weeks. However, demolition of membranes in 8 weeks after implantation was highest in Guidor membranes and followed by S-membranes. Biocompatibilityof two kinds of biodegradable membranes including Guidor and S-mambrane were shown to be well tolerated to the surrounding tissue, and were minimal accumulation of inflammatory cell infiltration around the implanted membranes to compare with Gore-tex membrane. Regeneration of defected alveolar bone was initiated from two weeks of membrane implantation and new bone formation was gradually increased from that time. However, pattern of new bone formation on the defected areas of two kinds of biodegrable membranes was almost similar and quite competitive comparing with Gore-tex membrane. These results implicate that bioresorbable membranes should be highly useful tool for guided tissue regeneration of periodontal defects.

• 대한기계학회논문집B
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• 제38권5호
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• pp.413-421
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• 2014

제습 냉방시스템은 증발식 냉각기를 이용하여 공조 공기를 냉각하는 시스템으로 전기구동 냉각기 없이 열에너지만으로 냉방 공급을 수행할 수 있다. 따라서, CFC 계열의 냉매 사용에 의한 오존층 파괴 및 하절기 냉각기 가동에 의한 첨두 전력부하의 증가 등 기존의 냉방시스템이 야기하는 여러 가지 문제점들을 해결할 수 있다. 본 연구에서는 제습 냉방시스템의 효율을 향상시키기 위해 냉방 성능과 엑서지 해석을 수행하였다. 특히 열역학 제2법칙에 근거한 엑서지 해석을 이용할 경우 전체시스템과 구성요소에서의 엑서지 파괴의 원인을 분석함으로써 시스템의 효율과 관련된 주제에 대하여 더욱 본질적인 측면에서 접근할 수 있다. 본 연구의 목적은 재생온도와 외기조건의 변화에 따른 재생 증발식 냉각기를 이용한 제습 냉방시스템의 성능계수, 냉방용량, 엑서지 성능을 평가하는 것이다.

• Animal Bioscience
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• 제37권5호
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• pp.896-907
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• 2024

Objective: The potential of aqueous extract of Christ's thorn jujube (Ziziphus spina-christi) leaves (SLAE) to reduce the negative impacts of heat stress on production performance and physiological traits was investigated in dual-purpose layers under subtropical farming. Methods: A total of 200, 25-week-old laying hens (Inshas strain) were randomly assigned to four dietary treatments including SLAE at 0, 2.5, 5.0, and 7.5 mL/kg, respectively. The average temperature-humidity index value was 26.69 during the experimental period. The SLAE contained saponin (0.045%), total flavonoid content of 17.9 mg of quercetin equivalent/100 g and overall antioxidant capacity concentration of 17.9 mg of ascorbic acid equivalent/100 g. Results: The maximum final body weight (BW), BW gain, egg weight, number, and mass occurred at the level of SLAE7.5 inclusion. The egg quality was significantly higher in SLAE groups than in control, and overall, SLAE7.5 had the most favorable influence at 28 and 32 weeks. Liver and kidney function, as well as lipids profile, improved significantly by SLAE inclusion; the lowest concentrations of these parameters were in SLAE7.5 hens. Treatment with SLAE7.5 increased total antioxidant capacity and endogenous antioxidant enzymes compared to control, whereas no effect on superoxide dismutase was noticed. Conclusion: The addition of SLAE at 7.5 mL/kg diet improved egg laying performance and quality, metabolic profiles, and antioxidant status during hyperthermia conditions.

• 식물조직배양학회지
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• 제22권3호
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• pp.143-148
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• 1995

벼의 뿌리조직을 기내배양하여 배발생캘러스의 형성과 식물체 재분화율의 품종간 차이 및 완숙배와 뿌리조직에서 유래된 캘러스의 현탁배양 기간별 부정배 형성정도와 식물체 재분화율 등에 대한 몇가지 실험을 수행하여 얻어진 결과를 요약하면 다음과 같다. 벼 뿌리조직으로부터 캘러스 형성 및 식물체 재분화 능력의 품종간 차이는 뚜렷하게 나타났으며, 자포니카형 품종들이 통일형 품종에 비해 캘러스의 생장량도 많고 식물체 재분화율도 높은 경향이었고, 공시품종 중 "영덕벼"의 식물체 재분화율이 13%로 가장 높았다. 뿌리 및 현미배양에서 형성된 캘러스를 고체배지에서 2 주 간격으로 7회 계대배양한 바, 계대배양 횟수가 증가됨에 따라 식물체 재분화율이 증가되었다가 5회째부터는 점차 감소하였다. 뿌리조직에서 형성된 캘러스의 현탁배양에서 모양이 둥근세포와 그들의 세포괴는 배양 24일 후에 최대치를 나타내었고 그 이후는 감소하였다. 현탁배양 기간별 뿌리조직에서 형성된 캘러스의 체세포배 형성률은 배양 90일까지는 배양기간이 길어질 수록 증가하였으나, 그 이후는 감소하였고, 식물체 재분화율도 배양기간이 길어질수록 감소하는 경향이었다.소하는 경향이었다.

• Progress in Superconductivity
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• 제14권1호
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• pp.66-70
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• 2012

Superconductor flywheel energy storage system (SFESs) is an electro-mechanical battery with high energy storage density, long life, and good environmental affinity. SFESs have been developed for application to a regenerative power of train, the storage of distributed power sources such as solar and wind power, and a power quality improvement. As superconductor bearing is completely passive, it is not necessary to control a system elaborately but accurate analysis in mechanical properties of the HTS bearing is very important for application to SFESs. Stiffness and damping properties are the main index for evaluation the capacity of HTS bearings and make it possible to adjust rotordynamic properties while operating the rotor-bearing system. The superconductor bearing consists of a stator containing single grain YBCO bulks, a ring-type permanent magnet rotor with a strong magnetic field that can reach the bulk surface, and a bearing support for assembly to SFESs frame. In this study, we investigated the stiffness and damping properties of superconductor bearings in 35 kWh SFESs. Finally, we found that 35 kWh superconductor bearing has uniform stiffness properties depend on the various orientations of rotor vibration. We discovered total damping coefficient of superconductor bearing is affected by not only magnetic damping in superconductor bulk but also external damping in bearing support. From the results, it is confirmed that the conducted evaluation can considerably improve energy storage efficiency of the SFESs, and these results can be used for the optimal capacity of superconductor bearings of the SFESs.