Yeon Shik Choi

Therapeutic Effects of Full Spectrum Light on the Development of Atopic Dermatitis-like Lesions in NC/Nga Mice

Full spectrum light (FSL) includes UVA, visible light and infrared light. Many studies have investigated the application of FSL in severe cases of atopic dermatitis (AD) in humans; however, FSL has not yet been studied in an animal model. The purpose of this study was to evaluate the therapeutic effects of FSL on AD‐like skin lesions using NC/Nga mice, with the aim of mitigating itching and attenuating the expression of adhesion molecules. We examined the effects of FSL on mite allergen‐treated NC/Nga mice by assessing skin symptom severity, ear thickness, serum IgE levels, and the cytokine expression. We examined the histology of lesions using hematoxylin–eosin, toluidine blue and immunohistochemical staining. Our findings suggest that FSL phototherapy exerts positive therapeutic effects on Dermatophagoides farinae (Df)‐induced AD‐like skin lesions in NC/Nga mice by reducing IgE levels, thus promoting recovery of the skin barrier. The mechanisms by which FSL phototherapy exerts its effects may also involve the inhibition of scratching behavior, reduction of IL‐6 levels and reductions in adhesion molecule expression. The present study indicates that FSL phototherapy inhibits the development of AD in NC/Nga mice by suppressing cytokine, chemokine and adhesion molecule expression, and thus, could potentially be useful in treating AD.

A Cooperative Metabolic Syndrome Estimation With High Precision Sensing Unit

In this letter, we discuss a sensor-integrated system model for metabolic syndrome prediction with workflow system. This model measures not only a cell temperature variation using invasive method but also controlling simulation for metabolic syndrome prediction. To identify the system realization, we discuss the schemes for predicting metabolic syndrome from measurement of mitochondrial activity by using high precision sensors and integrated simulation model of human energetic under high performance workflow computing environment. To predict metabolic syndrome, we built a sensor-integrated chamber that had network interface to deliver analysis results of human cells, annotation data from public hospital, and metabolic data. Using the proposed system, we showed the possibility to evaluate the functionality of human mitochondria and analyze energy metabolism.

Novel wearable-type biometric devices based on skin tissue optics with multispectral LED–photodiode matrix

In this study, we examined the possibility of using a multispectral skin photomatrix (MSP) module as a novel biometric device. The MSP device measures optical patterns of the wrist skin tissue. Optical patterns consist of 2 × 8 photocurrent intensities of photodiode arrays, which are generated by optical transmission and diffuse reflection of photons from LED light sources with variable wavelengths into the wrist skin tissue. Optical patterns detected by the MSP device provide information on both the surface and subsurface characteristics of the human skin tissue. We found that in the 21 subjects we studied, they showed their unique characteristics, as determined using several wavelengths of light. The experimental results show that the best personal identification accuracy can be acquired using a combination of infrared light and yellow light. This novel biometric device, the MSP module, exhibited an excellent false acceptance rate (FAR) of 0.3% and a false rejection rate (FRR) of 0.0%, which are better than those of commercialized biometric devices such as a fingerprint biometric system. From these experimental results, we found that people exhibit unique optical patterns of their inner-wrist skin tissue and this uniqueness could be used for developing novel high-accuracy personal identification devices.

Needle-free jet injection of hyaluronic acid improves skin remodeling in a mouse model

PURPOSE The purpose of this study was to improve methods of jet injection using a mouse model. We investigated the mechanism of action, efficacy, and safety of the pneumatic device using injection of hyaluronic acid (HA) solution into a mouse model. METHODS We evaluated the efficacy and safety of an INNOJECTOR™ pneumatic device that pneumatically accelerates a jet of HA solution under high pressure into the dermis of mouse skin. We examined the treatment effects using skin hybrid model jet dispersion experiments, photographic images, microscopy, and histological analyses. RESULTS Use of the INNOJECTOR™ successfully increased dermal thickness and collagen synthesis in our mouse model. Jet dispersion experiments were performed using agarose gels and a polyacrylamide gel model to understand the dependence of jet penetration on jet power. The mechanisms by which pneumatic injection using HA solution exerts its effects may involve increased dermal thickening, triggering of a wound healing process, and activation of vimentin and collagen synthesis. CONCLUSIONS Collagen synthesis and increased dermal thickening were successfully achieved in our mouse model using the INNOJECTOR™. Pneumatic injection of HA under high pressure provides a safe and effective method for improving the appearance of mouse skin. Our findings indicate that use of the INNOJECTOR™ may induce efficient collagen remodeling with subsequent marked dermal layer thickening by targeting vimentin.

The Fine Scratches of the Spectacle Frames and the Allergic Contact Dermatitis

Background Spectacle contact allergy is not infrequent. The fine scratches on the spectacle frames which may play a role in the sensitization to the potential allergenic components have not been studied. Objective We sought the relationship between the scratches on the spectacle frames and the allergic contact dermatitis (ACD) in the Republic of Korea. Methods A total of 42 Korean patients with ACD at the spectacle contact sites were enrolled. Their spectacle frames were examined with the dimethylglyoxime (DMG) test and analyzed by the scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Patch tests (thin-layer rapid use epicutaneous test [TRUE tests]) were performed to identify the skin allergens. Results The DMG-positive spectacle frames were identified in 78.5% of the frames. The SEM results showed that there were more scratches on the skin-contacting parts of the spectacle frames than the non-skin-contacting parts of the same frames. In the EDS findings, the mean nickel content (weight, %) of the spectacle frames was 15.7±5.5, and the mean chromium content was 20.3±3.4 at the skin-contacting parts. In the TRUE tests, nickel sulphate was the most common allergen (31 cases, 73.8%), and potassium dichromate was the second (9 cases, 21.4%). Three patients presented simultaneous positive reactions with nickel sulphate and potassium dichromate. Conclusion Minor visible and non-visible fine scratches on the spectacle frames may present the provocation factors of the ACD. Nickel sulphate was the most common allergen suspected of provoking the spectacle frame-induced ACD, followed by potassium dichromate.

An optical system to measure the thickness of the subcutaneous adipose tissue layer

To measure the thickness of the subcutaneous adipose tissue layer, a novel non-invasive optical measurement system (λ=1300 nm) is introduced. Animal and human subjects are used for the experiments. The results of human subjects are compared with the data of ultrasound device measurements, and a high correlation (r=0.94 for n=11) is observed. There are two modes in the corresponding signals measured by the optical system, which can be explained by two-layered and three-layered tissue models. If the target tissue is thinner than the critical thickness, detected data using diffuse reflectance method follow the three-layered tissue model, so the data increase as the thickness increases. On the other hand, if the target tissue is thicker than the critical thickness, the data follow the two-layered tissue model, so they decrease as the thickness increases.

Targeting of sebaceous glands to treat acne by micro-insulated needles with radio frequency in a rabbit ear model

Many studies have investigated the application of micro‐insulated needles with radio frequency (RF) to treat acne in humans; however, the use of a micro‐insulated needle RF applicator has not yet been studied in an animal model. The purpose of this study was to evaluate the effectiveness of a micro‐insulated needle RF applicator in a rabbit ear acne (REA) model.

The microneedle roller is an effective device for enhancing transdermal drug delivery.

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Development of a non‐invasive measurement system to the thickness of the subcutaneous adipose tissue layer

Background/purpose:  It is important to measure the thickness of hypodermis, including the subcutaneous fat layer in several fields such as global assessment of nutritional status and monitoring of dietary manipulation. It also provides useful information concerning the amount of peripheral adipose tissue and can be used as an index of obesity.

Design and Optical Characterization of Passive Pixel with Sensitivity-Improved InGaAs/InP Phototransistors Considering Light-Dependent Shunt Resistance for Near Infrared Imaging Applications

In this study, a InGaAs/InP passive unit pixel with an optical-sensitivity-improved heterojunction phototransistor (HPT) for array imaging applications has been designed and characterized for low-light signal detection considering light-dependent shunt resistance. Using the proposed devices, a 1×256 highly sensitive linear array chip with suitable shunt resistance has been fabricated and characterized. The designed passive unit pixel consists of one photodetector and one select transistor with a collector–base terminal tied configuration for a wide dynamic range. We also present epitaxial structures and an equivalent model to optimize optical gain and shunt resistance characteristics. The device operation mechanism and experimental results are discussed. The experimental results show that our device has an optical sensitivity of 118 A/W, which is significantly higher than that of a conventional PIN photodetector with the same light-absorbing area. This high sensitivity originates from the optical gain-enhanced device structure. A typical optical gain is approximately 236, which means HPTs are 236-fold more sensitive than PIN photodetectors. The proposed HPT also has tens of kΩ shunt resistance with high optical sensitivity under low illumination, which is sufficient for effective signal conversion through a transimpedance amplifier circuit.