Yoon Ho Lee

Effect of platelet-rich plasma on ultraviolet b-induced skin wrinkles in nude mice

BACKGROUND Platelet-rich plasma (PRP) is researched and used in many clinical fields as it contains an abundance of various growth factors. Recently, a topical injection of PRP has been clinically tried for treatment of photoageing-related skin wrinkles. Nevertheless, there have been only a few studies including objective data or explaining the mechanisms of PRP. Therefore, the authors performed animal experiments to collect laboratory data and to infer the basal mechanism of the effect of PRP on skin rejuvenation. METHODS Mice photoaged by ultraviolet B (UVB) irradiation for 8 weeks were divided into three groups (no-treatment group, saline injected group and PRP-injected group) with 10 mice in each group. After 4 weeks, the degree of wrinkle formation was compared among three groups by replica analysis, and skin biopsies were performed. An additional in vitro assay with growth-factor-neutralising antibodies was performed to evaluate whether growth factors contained in PRP could accelerate fibroblast proliferation and collagen production, which may play a major role in skin rejuvenation. RESULTS The wrinkles in the PRP-injected group were significantly reduced than in the other groups. Biopsy results indicated that the dermal layer was remarkably thicker in the PRP-injection group. In in vitro assay, fibroblast proliferation and collagen production were increased in the experimental group through growth factors in the PRP. CONCLUSION Although more in vivo studies and research about the mechanism of PRP are required, the results of this study indicate that PRP is effective in the rejuvenation of photoaged skin.

Fabrication of low-temperature solid oxide fuel cells with a nanothin protective layer by atomic layer deposition

Anode aluminum oxide-supported thin-film fuel cells having a sub-500-nm-thick bilayered electrolyte comprising a gadolinium-doped ceria (GDC) layer and an yttria-stabilized zirconia (YSZ) layer were fabricated and electrochemically characterized in order to investigate the effect of the YSZ protective layer. The highly dense and thin YSZ layer acted as a blockage against electron and oxygen permeation between the anode and GDC electrolyte. Dense GDC and YSZ thin films were fabricated using radio frequency sputtering and atomic layer deposition techniques, respectively. The resulting bilayered thin-film fuel cell generated a significantly higher open circuit voltage of approximately 1.07 V compared with a thin-film fuel cell with a single-layered GDC electrolyte (approximately 0.3 V).

The effect of growth hormone on fibroblast proliferation and keratinocyte migration

BACKGROUND The beneficial effects of growth hormones (GHs) on wound healing have been reported. Although the mechanism of how GH promotes wound healing is unclear, there are reports showing that the principal factor lies in the GH-stimulated production of IGF-1 in topical wounds. In this study, a human primary cell model was devised to examine how the topical application of GHs affects fibroblast proliferation and keratinocyte migration, which play fundamental roles in wound healing. METHODS The fibroblasts were cultured in media with different concentrations of GH. The amount of fibroblast proliferation was assessed using a tetrazolium-based colourimetric assay (MTT assay). The amount of newly formed IGF-I mRNA was measured by reverse transcription and polymerase chain reaction (RT-PCR). Keratinocyte migration was compared using a migration assay. RESULTS Fibroblast proliferation was significantly higher in the experimental group than in the control group (the absorbance of 2.5IU L(-1) GH applied group: 0.3954+/-0.056, control group: 0.2943+/-0.0554, P<0.05), and the promotion of IGF-I formation by fibroblasts was observed. There was more keratinocyte migration in the experimental group than in the control group (the remaining gap in the 2.5IU L(-1) GH applied group after keratinocyte migration: 46.57+/-2.22% of the primary gap, control group: 75.14+/-3.44%, P<0.05). CONCLUSION GH enhances the local formation of IGF-1, which activates fibroblast proliferation and keratinocyte migration. These results highlight the potential of the topical application of GHs in the treatment of wounds.

Boosting the Performance of Organic Optoelectronic Devices Using Multiple-Patterned Plasmonic Nanostructures

Multiple-patterned nanostructures prepared by synergistically combining block-copolymer lithography with nano-imprinting lithography have been used as back reflectors for enhancing light absorption in organic optoelectronic devices. The multiple-patterned electrodes have significantly boosted the performance of organic photovoltaics and photo-transistors, owed to the highly effective light scattering and plasmonic effects, extending the range of their practical applications.

Supramolecular Nanostructures of Chiral Perylene Diimides with Amplified Chirality for High‐Performance Chiroptical Sensing

Chiral supramolecular nanostructures with optoelectronic functions are expected to play a central role in many scientific and technological fields but their practical use remains in its infancy. Here, this paper reports photoconductive chiral organic semiconductors (OSCs) based on perylene diimides with the highest electron mobility among the chiral OSCs and investigates the structure and optoelectronic properties of their homochiral and heterochiral supramolecular assemblies from bottom-up self-assembly. Owing to the well-ordered supramolecular packing, the homochiral nanomaterials exhibit superior charge transport with significantly higher photoresponsivity and dissymmetry factor compared with those of their thin film and monomeric equivalents, which enables highly selective detection of circularly polarized light, for the first time, in visible spectral range. Interestingly, the heterochiral nanostructures assembled from co-self-assembly of racemic mixtures show extraordinary chiral self-discrimination phenomenon, where opposite enantiomeric molecules are packed alternately into heterochiral architectures, leading to completely different optoelectrical performances. In addition, the crystal structures of homochiral and heterochiral nanostructures have first been studied by ab initio X-ray powder diffraction analysis. These findings give insights into the structure-chiroptical property relationships of chiral supramolecular self-assemblies and demonstrate the feasibility of supramolecular chirality for high-performance chiroptical sensing.

Surgical correction of progressive hemifacial atrophy with onlay bone graft combined with soft tissue augmentation.

Objective Moderate-to-severe Parry-Romberg syndrome involves progressive atrophy of facial bony structures as well as changes in skin and subcutaneous tissue. To correct facial asymmetry in PRS patients, it is important to restore facial bony alignment and obtain a symmetrical appearance. Methods The authors propose a new combination method of onlay bone grafting and adipofascial free flap. Applying this technique, we performed rib bone graft with concomitant free flap transfer in 10 patients. All patients showed moderate-to-severe findings of PRS, involving skull deformity. Both male and female were 4 and 6 patients each, and the age of the patients at which they received surgery ranged from 10 to 52 years, with an average of 24.8 years of age. During the follow-up period, ancillary procedures including dermofat graft and hyaluronic acid filler injections were performed to achieve fine facial contour and facial symmetry. Results There were no severe complications such as infection or postoperative bleeding. All patients were satisfied with the result, and postoperative CT scanning revealed successful uptake of grafted bone. Conclusions Onlay frame bone graft by using rib bone as donor material, with combination of facial fat free flap transfer can be an excellent choice in restoring facial symmetry in severe cases of progressive hemifacial atrophy.

Properties of nanostructured undoped ZrO2 thin film electrolytes by plasma enhanced atomic layer deposition for thin film solid oxide fuel cells

Nanostructured ZrO2 thin films were prepared by thermal atomic layer deposition (ALD) and by plasma-enhanced atomic layer deposition (PEALD). The effects of the deposition conditions of temperature, reactant, plasma power, and duration upon the physical and chemical properties of ZrO2 films were investigated. The ZrO2 films by PEALD were polycrystalline and had low contamination, rough surfaces, and relatively large grains. Increasing the plasma power and duration led to a clear polycrystalline structure with relatively large grains due to the additional energy imparted by the plasma. After characterization, the films were incorporated as electrolytes in thin film solid oxide fuel cells, and the performance was measured at 500 °C. Despite similar structure and cathode morphology of the cells studied, the thin film solid oxide fuel cell with the ZrO2 thin film electrolyte by the thermal ALD at 250 °C exhibited the highest power density (38 mW/cm2) because of the lowest average grain size at cathode/electro...

Umbilical reconstruction using a modified inverted C-V flap with conjoint flaps

Abstract The umbilicus is an important aesthetic feature of the abdomen. Because of its location, the umbilicus can be injured after abdominal surgical procedures. Various methods have been devised to reconstruct the umbilicus by using local flaps, purse-string sutures, or a cartilage graft, but there are no ideal methods. The authors have created a modified inverted C-V flap with conjoint flaps. A 10-year-old boy presented with deformed umbilicus because he had undergone surgical correction of an omphalocele. The drawback of the traditional C-V flap method is the transverse long abdominal scar because of the long length of the V flap. However, by using two conjoint flaps at the superior part of the C-V flap, the length of V flap can be more short and the umbilical wall can be reconstructed by rotation of two conjoint flaps. It is also good for making a sinusoidal pocket and it makes the umbilicus deeper and more natural-looking. After the operation, there were no complications like flap necrosis, infection, haematoma, and so on. The patient was satisfied with the results The patient had a more attractive umbilicus than the one with the other previous technique. This new method makes a natural-looking umbilicus with less of a transverse scar and an adequate sinusoidal pocket and umbilical wall.

Versatility of retroauricular mastoid donor site: a convenient valuable warehouse of various free graft tissues in cosmetic and reconstructive surgery.

Abstract Soft-tissue deficiency is a critical issue in facial cosmetic and reconstructive surgery. Harvesting autografts from other anatomical sites has been a common practice in overcoming soft-tissue insufficiency for many years. However, donor-site complications and visible scars are of important concerns. Therefore, we would like to introduce an alternative donor site of free-tissue grafts and its inherent advantages: the retroauricular mastoid area located along the mastoid hair line. From August 1991 to June 2011, we performed facial reconstructive surgeries for cosmetic correction of disfigurements from both congenital and complications of previous cosmetic procedures on a total of 213 patients. These patients had undergone either 1 or more facial cosmetic surgeries in the past. In this study, our primary goal focused on revising facial asymmetries or defects from previous surgical scars, tissue contraction, undercorrection, or underdevelopment. For autograft harvesting, we incised an elliptical shape along the retroauricular hairline. We then harvested sufficient amount of skin, dermal fat, fascia, or a piece of the mastoid bone if needed. After harvesting, we closed the incisional area and covered it with a compressive dressing. In evaluation of our results, we compared the preoperative photographs with postoperative and constructed a survey on patient satisfaction. Overall, the patients in this study were greatly satisfied with their surgical results. No major complications were reported. As a result of our long-term study, we believe that the retroauricular mastoid area has been shown to be an indispensable donor site for a variety of autograft tissues in terms of safety, convenience, and versatility of its unique structural composition consisting of skin, dermal fat, fascia, and bone.

Onlay Rib Bone Graft in Elevation of Reconstructed Auricle: 17 Years of Experience

Background A cartilage wedge block and covering flap are standard procedures for firm elevation of the ear in microtia correction. However, using costal cartilage for elevation of the reconstructed auricle can be insufficient, and the fixed cartilage wedge block may be absorbed or may slip out. Furthermore, elevating covering flaps is time-consuming and uses up fascia, a potential source of reconstruction material. Therefore, we propose an innovative method using autologous onlay rib bone graft for auricular elevation of microtia. Methods From February 1995 to August 2012, 77 patients received a first stage operation with a rib cartilage framework graft. In the second stage operation, a small full thickness of rib bone was harvested through the previous donor scar. The bihalved rib bone was inserted into the subperiosteal pocket beneath the cartilage framework. Results The follow-up time ranged from 1 month to 17 years, with a mean of 3 years. All of the patients sustained the elevation of their ears very well during the follow-up period. Donor site problems, except for hypertrophic scars, were not observed. Surgery-related complications, specifically skin necrosis, infection, or hematoma, occurred in 4 cases. Conclusions Onlay rib bone graft used to elevate the reconstructed auricle is a more anatomically appropriate material than cartilage, due to the bone-to-bone contact between the bone graft and the temporal bone. Postoperative minor correction of the elevation degree is straightforward and the skin graft survives better. Therefore, reconstructed auricle elevation using onlay rib bone graft is a useful and valuable method.