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Park, Eun-Jung,Cho, Wan-Seob,Jeong, Jayoung,Yi, Jong-heop,Choi, Kyunghee,Kim, Younghun,Park, Kwangsik The Pharmaceutical Society of Japan 2010 Journal of Health Science Vol.56 No.4
<P>Cerium oxide nanoparticles have a high thermodynamic affinity for oxygen and sulfur, which makes them useful in applications such as catalysts, solar cells, and gas sensors. In this study, we investigated the effects of intratracheal instillation of cerium oxide nanoparticles on the inflammatory responses in mice. The number of neutrophils in bronchoaveolar lavage (BAL) fluids was significantly elevated on day 1 after instillation. Inflammatory cytokines, such as interleukin (IL)-1, tumor necrosis factor (TNF)-α, and IL-6, were also increased in BAL fluid and the cytokine increase initiated the differentiation of naive T cells, followed by the induction of Th1-type cytokines [IL-12 and interferon (IFN)-γ] and Th2-type cytokines (IL-4, IL-5, and IL-10). The secretion of Th1-type cytokines was more dominant than that of Th2-type cytokines. The inflammatory responses were maintained for 28 days by a positive feedback stimulation of IFN-γ and IL-10. In the lung, the expression of inflammatory genes was increased in a time-dependent manner, and granuloma formation appeared on day 14 after instillation. This suggests that intratracheal instillation of cerium oxide nanoparticles causes a delayed-type hypersensitivity reaction and lung fibrosis in mice.</P>
An analysis of a humidifier disinfectant case from a toxicological perspective
Park, Kwangsik The Korean Society of Environmental Toxicology 2016 환경독성보건학회지 Vol.31 No.-
An analysis of patients and fatalities due to exposure to polyhexamethylene guanidine (PHMG) shows that PHMG causes mainly lung diseases such as pulmonary fibrosis. However, no research on the other organs has been conducted on this matter yet. So, an in-depth discussion on toxicological techniques is needed to determine whether or not PHMG is toxic to organs other than just the lungs. For the test of target organ toxicity by PHMG exposure, a toxicokinetic study must first be conducted. However, measurement method for PHMG injected into the body has not yet been established because it is not easy to analyze polymer PHMG, so related base studies on analytical technique for PHMG including radio-labeling chemistry must come first. Moreover, research on exposure-biomarker and effect-biomarker must also be conducted, primarily related to clinical application. Several limitations seem to be expected to apply the biomarker study to the patient because much time has passed after exposure to the humidifier disinfectant. It is why a more comprehensive toxicological researches must be introduced to the causality for the victims.
Effect of the Thermal Conductivity on Resistive Switching in GeTe and Ge2Sb2Te5 Nanowires.
Park, Sungjin,Park, Dambi,Jeong, Kwangsik,Kim, Taeok,Park, SeungJong,Ahn, Min,Yang, Won Jun,Han, Jeong Hwa,Jeong, Hong Sik,Jeon, Seong Gi,Song, Jae Yong,Cho, Mann-Ho American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.39
<P>The thermal conduction characteristics of GeTe and Ge2Sb2Te5(GST) nanowires were investigated using an optical method to determine the local temperature by Raman spectroscopy. Since the localization of surface charge in a single-crystalline nanostructure can enhance charge-phonon scattering, the thermal conductivity value (관) of single crystalline GeTe and GST nanowires was decreased significantly to 1.44 Wm(-1) K(-1) for GeTe and 1.13 Wm(-1) K(-1) for GST, compared to reported values for polycrystalline structures. The SET-to-RESET state in single-crystalline GeTe and GST nanowires are characteristic of a memory device. Unlike previous reports using GeTe and GST nanowires, the SET-to-RESET characteristics showed a bipolar switching shape and no unipolar switching. In addition, after multiple cycles of operation, a significant change in morphology and composition was observed without any structural phase transition, indicating that atoms migrate toward the cathode or anode, depending on their electronegativities. This change caused by a field effect indicates that the structural phase transition does not occur in the case of GeTe and GST nanowires with a significantly lowered thermal conductivity and stable crystalline structure. Finally, the formation of voids and hillocks as the result of the electromigration critically degrades device reliability.</P>
An analysis of a humidifier disinfectant case from a toxicological perspective
Kwangsik Park 환경독성보건학회 2016 환경독성보건학회지 Vol.31 No.-
An analysis of patients and fatalities due to exposure to polyhexamethylene guanidine (PHMG) shows that PHMG causes mainly lung diseases such as pulmonary fibrosis. However, no research on the other organs has been conducted on this matter yet. So, an in-depth discussion on toxicological techniques is needed to determine whether or not PHMG is toxic to organs other than just the lungs. For the test of target organ toxicity by PHMG exposure, a toxicokinetic study must first be conducted. However, measurement method for PHMG injected into the body has not yet been established because it is not easy to analyze polymer PHMG, so related base studies on analytical technique for PHMG including radio-labeling chemistry must come first. Moreover, research on exposure-biomarker and effect-biomarker must also be conducted, primarily related to clinical application. Several limitations seem to be expected to apply the biomarker study to the patient because much time has passed after exposure to the humidifier disinfectant. It is why a more comprehensive toxicological researches must be introduced to the causality for the victims.
랫드의 혈액응고 및 혈소판 응집에 미치는 은나노 입자의 영향
박광식(Kwangsik Park),이연진(Yeonjin Lee) 大韓藥學會 2012 약학회지 Vol.56 No.6
Effects of citrate-capped silver nanoparticles (AgNPs) on the blood coagulation and platelet aggregation were investigated using whole blood, platelet rich plasma (PRP) and washed platelet obtained from SD male rats. To confirm the stability of AgNPs in the test, size distribution of the nanoparticles was measured in the vehicles including distilled water, serum, and platelet buffers. The average size of AgNPs was 20 nm in the vehicles, which means that the stability was maintained during the whole experimental period. When blood coagulation was monitored by using whole blood impedance aggregometer, coagulation was not observed at the concentration of 1, 10 and 50 ppm. Platelets in plasma or in buffer were not aggregated by AgNPs at the concentration of 1, 2 and 4 ppm, respectively. The test concentration of AgNPs could not be increased because the dark color of the nanoparticles impeded the transmission of light, which is an indicator of aggregation. Although the blood or platelets were pre-activated by collagen, thrombin, or ADP with sub-threshold level, aggregation was not observed at the test concentration. Microscopic observation also supported the result obtained by the aggregometer.