김지희 교수

Piezostacks are capable of producing very large forces, but they provide only limited displacements. Thus, the displacement amplification mechanism is necessary to make those actuators more efficient and useful. For this purpose, a two-bridge-type flexure hinge mechanisms in series in a three-dimensional structure is proposed in this study. To show the validity of the proposed mechanism, the kinematic analysis is carried out by a matrix method and by a finite element method, and then the amplifi

BACKGROUND: Owing to its potentially greater mechanical force on the implanted tissue, barbed thread is frequently used in face-lifting procedures. However, the long-term durability thereof remains controversial. Moreover, reports on underlying histologic and molecular changes resulting from face-lifting procedures are scarce. OBJECTIVE: To evaluate histologic and molecular changes induced by absorbable, barbed face-lifting thread in an animal model. MATERIALS AND METHODS: Fragments of monofilam

BACKGROUND: Recent advances in keloid management favor the administration of combination therapy over monotherapy. OBJECTIVE: The authors evaluated the safety and efficacy of combination therapy to treat keloids using fractional lasers, cryotherapy, and intralesional corticosteroids. MATERIALS AND METHODS: The authors performed a retrospective study involving 35 Korean patients. Each patient underwent treatment using the 1,550 nm nonablative fractional erbium-glass laser, followed by the 10,600

BACKGROUND: Extrinsic skin aging caused by atmospheric pollutants is associated with a sustained inflammatory response which is a significant risk factor for lentigines and melasma. AIMS: The aim of this study was to evaluate the efficacy of topical application of combination formulation of vitamin C, vitamin E, and ferulic acid as an adjuvant to Q-switched Nd:YAG (QSNY) lasers treatment in individuals with lentigines and melasma. METHODS: A single blinded, prospective, randomized split-face tri

BACKGROUND: The conditioned media from adipocyte-derived mesenchymal stem cells-conditioned media (ADSC-CM) contains cytokines and growth factors that stimulate hair regeneration. OBJECTIVE: We evaluated the efficacy and safety of human ADSC-CM treatment on patients who underwent nonablative fractional laser for the treatment of androgenetic alopecia (AGA). MATERIALS AND METHODS: Thirty patients who underwent nonablative fractional laser treatment were topically administered either ADSC-CM or pl

Emerging studies have revealed the involvement of high-mobility group box 1 (HMGB1) in systemic fibrotic diseases, yet its role in the cutaneous scarring process has not yet been investigated. We hypothesized that HMGB1 may promote fibroblast activity to cause abnormal cutaneous scarring. In vitro wound healing assay with normal and keloid fibroblasts demonstrated that HMGB1 administration promoted the migration of both fibroblasts with increased speed and a greater traveling distance. Treatment

Protein tyrosine kinase 7 (PTK7) is a catalytically inactive receptor tyrosine kinase that is also known as colon carcinoma kinase-4 (CCK-4). Recent reports have shown that PTK7 plays an important role in carcinogenesis, and it is known to be upregulated in gastric, colon and esophageal cancer, as well as in liposarcoma. However, the role of PTK7 in lung cancer has not been investigated. The aim of the present study was to investigate the expression levels and the role of PTK7 in lung cancer. We

Orally administered collagen peptides could contribute to antiaging by replacing the degraded extracellular matrix proteins caused by photoaging. This study aimed to evaluate the efficacy and safety of low-molecular-weight collagen peptides for treating photoaged and dry skin. In this randomized, placebo-controlled, parallel-group, double-blinded trial, we randomly assigned study participants (n = 100) to either the test product group or placebo group at a 1:1 ratio for 12 weeks. The wrinkle sca

The present study investigated the effect of topical application of Epidermidibacterium Keratini (EPI-7) ferment filtrate, which is a postbiotic product of a novel actinobacteria, on skin aging, by performing a prospective randomized split-face clinical study on Asian woman participants. The investigators measured skin biophysical parameters, including skin barrier function, elasticity, and dermal density, and revealed that the application of the EPI-7 ferment filtrate-including test product res

Previous studies described the involvement of extracellular signal-related kinase (ERK) in systemic fibrotic diseases, but the role of ERK in cutaneous scarring is unknown. Although hypoxia drives tissue fibrosis by activating hypoxia-inducible factor-1α (HIF-1α), the specific roles of hypoxia and associated ERK phosphorylation in abnormal fibroblast activity during cutaneous scarring are unclear. Here, we investigated whether pathologic myofibroblast-like keloid fibroblast activity is promoted

BACKGROUND: Fractional microneedle radiofrequency (FMRF) systems are popular options for treating acne scars. However, treatment efficacy when used in combination with traditional ablative fractional laser (AFL) and the safety profile with concomitant use of isotretinoin remain unknown. OBJECTIVE: The aim of this study was to assess the safety and efficacy of an early intervention combination treatment protocol for inflammatory acne and acne scars. MATERIALS AND METHODS: The electronic records o

BACKGROUND: Ablative CO2 fractional laser (AFL) is a common cosmetic procedure to improve skin laxity. However, due to prolonged downtime and the risk of postinflammatory hyperpigmentation, laser-assisted delivery of active ingredients as post-laser treatment has gained interest in past years. Among various active ingredients, human umbilical cord blood-derived mesenchymal stem cells (hUCBMSCs) can be a promising agent promoting skin regeneration. AIMS: We evaluated the efficacy and safety of a

One of the most frequent comorbidities that develop in chronically ill or immobilized patients is pressure ulcers, also known as bed sores. Despite ischemia-reperfusion (I/R)-induced skin lesion having been identified as a primary cause of pressure ulcers, wound management efforts have so far failed to significantly improve outcomes. Baicalin, or 5,6,7-trihydroxyflavone, is a type of flavonoid which has been shown to possess a variety of biological characteristics, including antioxidative and an

Human deciduous and permanent teeth exhibit different developmental processes, morphologies, histological characteristics and life cycles. In addition, their pulp tissues react differently to external stimuli, such as the pulp sensitivity test, dental trauma and pulp therapy materials. These suggest differences in gene expression and regulation, and in this study we compared gene-expression profiles of the human dental pulp from deciduous and permanent teeth. Pulp tissues from permanent premolar