Hyun-Kyu Kim

Acute toxicity and genotoxicity study of fermented traditional herb formula Guibi-tang.

ETHNOPHARMACOLOGY RELEVANCE Guibi-tang (Guipi-tang in Chinese and Kihi-to in Japanese) is a multi-herb traditional medicine commonly prescribed to treat psychoneurosis in East Asia. Although this medicine has been widely used, there is little available information on the safety and toxicity of Guibi-tang, especially on the fermented one. MATERIALS AND METHODS Guibi-tang, composed of 12 herbs, was fermented with bacteria and lyophilized. Single dose acute toxicity in rats was observed for 14 days after administration. Genetic toxicity of fermented Guibi-tang was evaluated on bacterial reverse mutation in Salmonella and Escherichia spp., chromosome aberrations in Chinese hamster ovary cells, and micronucleus formation in mice. Ingredients in FGBT were identified and quantified by high performance liquid chromatography-mass spectrometry. RESULTS In acute oral toxicity study, behavior, clinical signs and body weight changes were normal observing in all experimental animals. No revertant colonies were found in any bacterial cultures examined. Morphological or numerical anomalies and significant increased number of aberrant metaphases were not observed. Micronucleus assay showed no significant increases in the frequency of inducing micronuclei in any dose examined. Decursinol, decursin, glycyrrhizin, and 6-gingerol in fermented Guibi-tang were identified and quantitated. As a whole, no acute and genotoxic effects were found in all the assays and parameters analyzed. CONCLUSION Fermented Guibi-tang was recognized as safe and non-toxic, and therefore can be used for applications of traditional medicine in modern complementary and alternative therapeutics and health care.

From chips to dust: The MEMS shatter secure chip

This paper presents the implementation of a transience mechanism for silicon microchips via low-temperature postprocessing steps that transform almost any electronic, optical or MEMS substrate chips into transient ones. Transience is achieved without any hazardous or explosive materials. Triggered chip transience is achieved by the incorporation of a distributed, thermally-activated expanding material on the chip backside. When heated at 160°C the expanding material produces massive chip cleavage mechanically shattering the chip into a heap of silicon dust.

Chondroprotective Effects of a Standardized Extract (KBH-JP-040) from Kalopanax pictus, Hericium erinaceus, and Astragalus membranaceus in Experimentally Induced In Vitro and In Vivo Osteoarthritis Models

The aim of this study was to investigate the chondroprotective effect of a standardized extract (KBH-JP-040) of the Korean traditional herbs Kalopanax pictus Castor-Aralia, Hericium erinaceus (Bull.) Persoon, and Astragalus membranaceus Schischkin on in vivo and in vitro osteoarthritis (OA) models. Cultured rat chondrocytes were pre-treated with KBH-JP-040 (50, 100 and 200 μg/mL) for 1 h, then recombinant human IL-1α (rhIL-1α) for 24 h. For the in vivo model, rabbits (n = 60) were equally divided into experimental groups: normal control (NC), a collagenase-induced OA group, and OA groups treated with KBH-JP-040 (75, 100, and 150 mg/kg body weight) and celecoxib (Cx, 100 mg/kg) orally for 28 days. Treatment with KBH-JP-040 significantly attenuated inflammatory cytokines and matrix metalloproteinases (MMPs), suppressed the expression of IκBα, NF-κB, and JNK/p38 mitogen-activated protein (MAP) kinase, and upregulated aggrecan and collagen type-II expression in rhIL-1α-stimulated chondrocytes. Furthermore, the serum and synovial levels of inflammatory cytokines of rabbits also decreased in the treatment groups when compared with the OA group. Improved magnetic resonance imaging and histopathological findings further confirmed the therapeutic efficacy of KBH-JP-040 against OA. In conclusion, these results indicate that KBH-JP-040 possesses chondroprotective effects, suppressing inflammation and MMPs, and downregulating IκBα, NF-κB, and JNK/p38 MAP kinase-signaling pathways. This might be a potential therapeutic candidate for OA treatment.

Anti-diabetic Effects of Ethanol Extract from Bitter Melon in Mice Fed a High-fat Diet

ABSTRACT Present study aimed to determine the effect of ‘bitter melon’, a popularly used fruit in Bangladesh and several other Asian countries, on high-fat-diet-induced type 2 diabetes. To investigate the effect, ethanol extract from bitter melon (BME) as a dietary supplement with mouse chow was used. BME was found to significantly attenuate the high-fat diet (HFD) -induced body weight and total fat mass. BME also effectively reduced the insulin resistance induced by the HFD. Furthermore, dietary supplementation of BME was highly effective in increasing insulin sensitivity and reducing hepatic fat and obesity. These results indicate that BME could be effective in attenuating type 2 diabetes and could therefore be a preventive measure against type 2 diabetes.

Amplified chemomechanical comb gas sensor

We present a new type of amplified chemomechanical comb-type capacitive gas sensors (ACMs) consisting of a set of flexible sense fingers with asymmetric absorbing polymer patches and side electrodes. This device combines the high sensitivity features of stress-deformed gas sensors and parametric amplification. Preliminary experiments with water and ethanol vapors indicate that the sensitivity of these devices can be increased 3–4 fold via parametric gain induced by biasing one of the side electrodes. This gain can be further increased by symmetrically biasing the side fingers.

Picowatt gas sensing and resistance switching in tunneling nano-gap electrodes

Functionalized engineered nanogap electrodes (pair of electrodes separated by a gap of a few nanometers) are utilized as tunneling chemoresistors for gas sensing and resistance switching at the molecular scale. The nanogap device consists of two gold electrodes vertically separated by a very thin spacer of 2 nm of α-Si and ∼4 nm of dielectric (SiO2 or Al2O3). A ∼10 nm wide sidewall air gap is formed by etching the spacer along the edge of the electrodes followed by linker functionalization. After exposure to a gaseous chemical target (1,5-Diaminopentane), the target gas molecules adsorb onto the linker-coated surface bridging the two electrodes and establish an electrically conductive path. Preliminary electrical measurements indicate a nearly reversible decrease of electrical resistance between five to seven orders of magnitude when exposed to the target. The large change in resistance and the high value of resistance in air makes this device suitable as a candidate for a gas-triggered on-off switch with pW standby power consumption.