• Current Optics and Photonics
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• v.3 no.1
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• pp.1-7
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• 2019

Optical stimulation provides a promising alternative to electrical stimulation to selectively modulate tissue. However, developing noninvasive techniques to directly stimulate excitable tissue without introducing genetic modifications and minimizing cellular stress remains an ongoing challenge. Infrared (IR) light has been used to achieve optical pacing for electrophysiological studies in embryonic quail and mammalian hearts. Here, we demonstrate optical stimulation and pacing of the embryonic chicken heart using a pulsed infrared thulium laser with a wavelength of 1927 nm. By recording stereomicroscope outputs and quantifying heart rates and movements through video processing, we found that heart rate increases instantly following irradiation with a large spot size and high radiant exposure. Targeting the atrium using a smaller spot size and lower radiant exposure achieved pacing, as the heart rate synchronized with the laser to 2 Hz. This study demonstrates the viability of using the 1927 nm thulium laser for cardiac stimulation and optical pacing, expanding the optical parameters and IR lasers that can be used to modulate cardiac dynamics.

• Archives of Plastic Surgery
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• v.39 no.5
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• pp.534-539
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• 2012

Background Autologous fat grafting evolved over the twentieth century to become a quick, safe, and reliable method for restoring volume. However, autologous fat grafts have some problems including uncertain viability of the grafted fat and a low rate of graft survival. To overcome the problems associated with autologous fat grafts, we used uncultured adipose tissue-derived stromal cell (stromal vascular fraction, SVF) assisted autologous fat grafting. Thus, the purpose of this study was to evaluate the effect of SVF in a clinical trial. Methods SVF cells were freshly isolated from half of the aspirated fat and were used in combination with the other half of the aspirated fat during the procedure. Between March 2007 and February 2008, a total of 9 SVF-assisted fat grafts were performed in 9 patients. The patients were followed for 12 weeks after treatment. Data collected at each follow-up visit included clinical examination of the graft site(s), photographs for historical comparison, and information from a patient questionnaire that measured the outcomes from the patient perspective. The photographs were evaluated by medical professionals. Results Scores of the left facial area grafted with adipose tissue mixed with SVF cells were significantly higher compared with those of the right facial area grafted with adipose tissue without SVF cells. There was no significant adverse effect. Conclusions The subjective patient satisfaction survey and surgeon survey showed that SVF-assisted fat grafting was a surgical procedure with superior results.

• Tissue Engineering and Regenerative Medicine
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• v.15 no.6
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• pp.761-769
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• 2018

BACKGROUND: Bioprinting has recently appeared as a powerful tool for building complex tissue and organ structures. However, the application of bioprinting to regenerative medicine has limitations, due to the restricted choices of bio-ink for cytocompatible cell encapsulation and the integrity of the fabricated structures. METHODS: In this study, we developed hybrid bio-inks based on acrylated hyaluronic acid (HA) for immobilizing bio-active peptides and tyramine-conjugated hyaluronic acids for fast gelation. RESULTS: Conventional acrylated HA-based hydrogels have a gelation time of more than 30 min, whereas hybrid bio-ink has been rapidly gelated within 200 s. Fibroblast cells cultured in this hybrid bio-ink up to 7 days showed >90% viability. As a guidance cue for stem cell differentiation, we immobilized four different bio-active peptides: BMP-7-derived peptides (BMP-7D) and osteopontin for osteogenesis, and substance-P (SP) and Ac-SDKP (SDKP) for angiogenesis. Mesenchymal stem cells cultured in these hybrid bio-inks showed the highest angiogenic and osteogenic activity cultured in bio-ink immobilized with a SP or BMP-7D peptide. This bio-ink was loaded in a three-dimensional (3D) bioprinting device showing reproducible printing features. CONCLUSION: We have developed bio-inks that combine biochemical and mechanical cues. Biochemical cues were able to regulate differentiation of cells, and mechanical cues enabled printing structuring. This multi-functional bio-ink can be used for complex tissue engineering and regenerative medicine.

• Archives of Plastic Surgery
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• v.33 no.3
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• pp.289-293
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• 2006

By means of microsurgical free-tissue transfer providing a large amount of required tissue, the surgeon can resect tumoral tissue more safely, which allows tumor-free margins and enhances the reliability of the ablative surgery that otherwise could not be performed radically. The morbidity of elective free-tissue transfer seems to be quite low, carrying acceptable risks for most patients. But the elderly patients are at risk for cardiac and respiratory problems, deep vein thrombosis, pulmonary emboli and infection merely as a function of age. This study was undertaken to define further risks of the elderly population with regards to free-tissue transfer. We retrospectively reviewed our experience with 110 microsurgical free-tissue transfers for head and neck reconstruction in patients greater than 60 years of age. Microsurgical procedures in all cases were preformed by the plastic and reconstructive department at Yonsei medical center. The investigated parameters were patient demographics, past medical history, American Society of Anesthesiologists(ASA) status, site and cause of defect, the free tissue transferred and postoperative complication including free-flap success or failure. There were 46 patients in the age group from 60 to 64 years, 34 patients from 65 to 70 years, and 30 patients 70 years or older. There happened 3 flap losses, resulting in a flap viability rate of 97%. Patients with a higher ASA designation experienced more medical complication(p=0.05, 0.01, 0.03 in each age group I, II, III) but not surgical complication p=0.17, 0.11, 0.54 in each age group I, II, III). And the relationship between postoperative complication and age groups was not significant. These observations suggest that major determinant for postoperative medical complication be the patient's American Society of Anesthesiologists score, and chronologic age alone should not be an exclusion criterion when selecting patients for free-tissue transfer

• Archives of Reconstructive Microsurgery
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• v.24 no.2
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• pp.41-49
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• 2015

Free or pedicled vascularized fibular grafts (VFG) are useful for the reconstruction of large skeletal defects, particularly in cases of scarred or avascular beds, or in patients with combined bone and soft tissue defects. Compared to non-VFG, VEG, which contains living osteocytes and osteoblasts, maintains its own viability and serves as good osteoconductive and osteoinductive graft. Due to its many structural and biological advantages, the free fibular osteo- or osteocutaneous graft is considered the most suitable autograft for the reconstruction of long bone defects in the injured extremity. The traditional indication of VFG is the long bone and soft tissue defect, which cannot be reconstructed using a conventional operative method. Recently, the indications have been widely expanded not only for defects of midtibia, humerus, forearm, distal femur, and proximal tibia, but also for the arthrodesis of shoulder and knee joints. Because of its potential to allow further bone growth, free fibular epiphyseal transfer can be used for the hip or for distal radius defects caused by the radical resection of a tumor. The basic anatomy and surgical techniques for harvesting the VFG are well known; however, the condition of the recipient site is different in each case. Therefore, careful preoperative surgical planning should be customized in every patient. In this review, recently expanded surgical indications of VFG and surgical tips based on the author's experiences in the issues of fixation method, one or two staged reconstruction, size mismatching, overcoming the stress fracture, and arthrodesis of shoulder and knee joint using VFG are discussed with the review of literature.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.38.2-38.2
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• 2009

Regeration of natural tissuesor to create biological substitutes for defective or lost tissues and organs through the use of cells. In addition to cells and their porous, drugs are required to promote tissue regeneration. Therefore, the present studies were prepared using simvastatim loaded porous poly(lactide-co-glycolide) (PLGA) by double emulsion solvent evaporation water-in-oil-in-water technique (W/O/W) as drug delivery system strategies for injuring tissue. The resulting microspheres were evaluated for morphology, particle size, encapsulation efficiency, degradation of PLGA microspheres in vitro drug release and in vitro cell viability. Scanning electronic microscopic (SEM) showed that the porosities of the particles was changed by experimental conditions and cultured cells were attached well on porous microspheres surface. The X-ray diffraction (XRD) and differential scanning calometry (DSC) analysis indicate thatsimvastatim was highly dipersed in the microsphere at amorphousstate.

• Journal of the Ergonomics Society of Korea
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• v.29 no.4
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• pp.639-646
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• 2010

The APAM's quantitative effectiveness and comparative study in preventing and treating pressure ulcer has not been sufficiently evaluated mainly because of uncertainty of pressure load input and lack of interpretation of dynamic perfusion recovery characteristics of soft tissue. The purpose of this paper was to quantify and analyze the alternating pressure characteristics of APAM as a preventive measure for pressure ulcers. To quantify the alternating load to human body, we introduced alternating pressure profile concept and developed parametric model of the profile. Regarding pressure level and cycle time, 3 global and 7 local periodic parameters were used to define the profile such as light, standard, typical and heavy duty profile shape. Pressure impulse ratio of light duty is the lowest but pressure fluctuation is significantly high. For the same duty shape, contact conditions are changed with alternating cycle time and more dramatically in shorter alternating cycle time conditions. We can conclude that if we use shorter alternating cycle time on APAM's operation we can get more positive effects regarding to inflated contact time condition. We proposed the quantitative methods on tissue viability study of external loading by simultaneous measurement of interface pressure and tissue perfusion with proper alternating pressure profile conditions.

• Archives of Plastic Surgery
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• v.48 no.5
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• pp.549-552
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• 2021

Clinical applications of stromal cells obtained mechanically from adipose tissue are quite popular methods. However, generally accepted protocols still do not exist. In this study, three new delivery methods using different protocols are presented as innovative methods in accordance with an approach called "Indication-based protocols." In mechanical methods, before cutting the fat tissue with ultra-sharp blades, which we define as "Adinizing," mixing it with different liquids such as saline or plasma provides the stromal cells in liquid form with high number and viability as a final product. At the same time, since stromal cells and extracellular matrix are preserved by mechanical methods, it was deemed appropriate to use the term total stromal cells (TOST) instead of stromal vascular fraction for this final product, unlike the product obtained with the enzyme. TOST can be combined with plasma and used for dermal filling in "solid" form. In addition to this filling effect, it will also cause a change in the tissue regeneratively. Finally, the stromal cells obtained from liquid can be applied clinically in aerosol form with the help of nebulizer. We believe that three innovative delivery methods can be used successfully in the treatment of many clinical situations in the future.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.107-107
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• 2017

3D bioprinting is a technology to produce complex tissue constructs through printing living cells with hydrogel in a layer-by-layer process. To produce more stable 3D cell-laden structures, various materials have been developed such as alginate, fibrin and gelatin. However, most of these hydrogels are chemically bound using crosslinkers which can cause some problems in cytotoxicity and cell viability. On the other hand, thermosensitive hydrogels are physically cross-linked by non-covalent interaction without crosslinker, facilitating stable cytotoxicity and cell viability. The examples of currently reported thermosensitive hydrogels are poly(ethylene glycol)/poly(propylene glycol)/poly(ethylene glycol) (PEG-PPG-PEG) and poly(ethylene glycol)/poly(lactic acid-co-glycolic acid) (PEG/PLGA). Chitosan, which have been widely used in tissue engineering due to its biocompatibility and osteoconductivity, can be used as thermosensitive hydrogels. However, despite the many advantages, chitosan hydrogel has not yet been used as a bioink. The purpose of this study was to develop a bioink by chitosan hydrogel for 3D bioprinting and to evaluate the suitability and potential ability of the developed chitosan hydrogel as a bioink. To prepare the chitosan hydrogel solution, ${\beta}-glycerolphosphate$ solution was added to the chitosan solution at the final pH ranged from 6.9 to 7.1. Gelation time decreased exponentially with increasing temperature. Scanning electron microscopy (SEM) image showed that chitosan hydrogel had irregular porous structure. From the water soluble tetrazolium salt (WST) and live and dead assay data, it was proven that there was no significant cytotoxicity and that cells were well dispersed. The chitosan hydrogel was well printed under temperature-controlled condition, and cells were well laden inside gel. The cytotoxicity of laden cells was evaluated by live and dead assay. In conclusion, chitosan bioink can be a candidate for 3D bioprinting.

• Journal of Periodontal and Implant Science
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• v.38 no.4
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• pp.639-644
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• 2008

Purpose: The aim of this study was to compare the number of live and dead bacteria attached to, or within, the stratified squamous epithelium lining the tissue side of the gingival sulcus. Materials and Methods: A total of 50 patients was examined and classified into healthy or diseased sites according to inflammatory status of the gingival tissue. The surface of stratified squamous epithelium was removed by gentle scraping of the gingival sulcus with curettes. The cells were processed in the laboratory by density-gradient centrifugation to separate the epithelial cells from the loose bacteria and debris. The LIVE/$DEAD^{(R)}$ $BacLight^{TM}$ Bacterial Viability Kit was applied and the specimens were observed by an epifluorescent microscope and the number of bacteria was counted. Results: Live and dead bacteria were stained to green and red, irrespectively. Generally, the number of total bacteria in the diseased sites was significantly higher than in the healthy sites. The mean number of detected bacteria in the diseased sites was $58.6{\pm}36.0$ (red bacteria $10.4{\pm}9.2$ / green bacteria $48.2{\pm}30.5$), while it was $1.5{\pm}1.7$ in the healthy sites (red bacteria $0.1{\pm}0.3$ / green bacteria $1.4{\pm}1.5$). The percentage of red bacteria was $17.5{\pm}11.2%$ in the diseased sites and $2.0{\pm}5.8%$ in the healthy sites. Conclusion: The total number of bacteria in the diseased sites was significantly higher than that of the healthy sites. The ratio and the number of red bacteria were also significantly higher in the diseased sites.