• Molecules and Cells
• /
• v.20 no.3
• /
• pp.331-338
• /
• 2005

Ionizing radiation and doxorubicin both produce oxidative damage and double-strand breaks in DNA. Double-strand breaks and oxidative damage are highly toxic and cause cell cycle arrest, provoking DNA repair and apoptosis in cancer cell lines. To investigate the response of normal human cells to agents causing oxidative damage, we monitored alterations in gene expression in F65 normal human fibroblasts. Treatment with ${\gamma}$-irradiation and doxorubicin altered the expression of 23 and 68 known genes, respectively, with no genes in common. Both agents altered the expression of genes involved in cell cycle arrest, and arrested the treated cells in $G_2M$ phase 12 h after treatment. 24 h after ${\gamma}$-irradiation, the percentage of $G_1$ cells increased, whereas after doxorubicin treatment the percentage of $G_2M$ cells remained constant for 24 h. Our results suggest that F65 cells respond differently to ${\gamma}$-irradiation- and doxorubicin-induced DNA damage, probably using entirely different biochemical pathways.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
• /
• v.21 no.1
• /
• pp.70-82
• /
• 2008

Objective : The purpose of this study is to examine the effects of Baickbujasan(BB) on the skin damage and depigmentation. Method : The inhibition of tyrosinase activity, melanogenesis and cell viability in cultured B16 melanoma cells were measured. In order to test effects of reduction of melanogenesis, B16 F-10 mouse melanoma stem line was employed to extract melanin from cultured cell, where BB was added or not, and was dissolved in alkali for colorimetric analysis. Also, in order to test skin alteration in C57BL/6 after UV irradiation, the animals were grouped into a UV urradiation group and UV irradiation after BB application group. Dopa oxidase tissue staining was excuted to invesitage the change in the distribution of active melanin cell. The distribution of active melanin cell in inner skin of iNOS after damage from UVB irradiation and the manifestation condition of P53 which takes part in natural death of keratinocyte were examined. Result : The results indicate that BB has significant effects on tyrosinase activity, and melanogenesis in vivo test. BB seems to reduce C57BL/6, external dermatological damage, for instance, erythematous papule, eczema, loss of keratinocyte, reduction in pus, and relieves dermatological damages. Conclusion : BB can be applied externally for UV protection and depigmentation.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.1
• /
• pp.36-43
• /
• 2014

Magnesium-protoporphyrin IX (Mg-PPn), which is formed through chelation of protoporphyrin IX (PPn) with Mg ion by Mg chelatase, is the first intermediate for the (bacterio)chlorophyll biosynthetic pathway. Interestingly, Mg-PPn provides peroxidase activity (approximately $4{\times}10^{-2}units/{\mu}M$) detoxifying $H_2O_2$ in the presence of electron donor(s). The peroxidase activity was not detected unless PPn was chelated with Mg ion. Mg-PPn was found freely diffusible through the membrane of Escherichia coli and Vibrio vulnificus, protecting the cells from $H_2O_2$. Furthermore, unlike photosensitizers such as tetracycline and PPn, Mg-PPn did not show any phototoxicity, but rather it protected cell from ultraviolet (UV)-A-induced stress. Thus, the exogenous Mg-PPn could be used as an antioxidant and a UV block to protect cells from $H_2O_2$ stress and UV-induced damage.

• Molecules and Cells
• /
• v.40 no.2
• /
• pp.143-150
• /
• 2017

Homologous recombination (HR) is necessary for maintenance of genomic integrity and prevention of various mutations in tumor suppressor genes and proto-oncogenes. Rad51 and Rad54 are key HR factors that cope with replication stress and DNA breaks in eukaryotes. Rad51 binds to single-stranded DNA (ssDNA) to form the presynaptic filament that promotes a homology search and DNA strand exchange, and Rad54 stimulates the strand-pairing function of Rad51. Here, we studied the molecular dynamics of Rad51 and Rad54 during the cell cycle of HeLa cells. These cells constitutively express Rad51 and Rad54 throughout the entire cell cycle, and the formation of foci immediately increased in response to various types of DNA damage and replication stress, except for caffeine, which suppressed the Rad51-dependent HR pathway. Depletion of Rad51 caused severe defects in response to postreplicative stress. Accordingly, HeLa cells were arrested at the G2-M transition although a small amount of Rad51 was steadily maintained in HeLa cells. Our results suggest that cell cycle progression and proliferation of HeLa cells can be tightly controlled by the abundance of HR proteins, which are essential for the rapid response to postreplicative stress and DNA damage stress.

• Steel and Composite Structures
• /
• v.51 no.1
• /
• pp.53-61
• /
• 2024

Aluminum foams sandwich panel (AFSP) has been used in engineering field, where cyclic loading is used in most of the applications. In this paper, the fatigue life of AFSP prepared by the bonding method was investigated through a three-point bending test. The mathematical statistics method was used to analyze the influence of different plate thicknesses and core densities on the bending fatigue life. The macroscopic fatigue failure modes and damage mechanisms were observed by scanning electron microscopy (SEM). The results indicate that panel thickness and core layer density have a significant influence on the bending fatigue life of AFSP and their dispersion. The damage mechanism of fatigue failure to cells in aluminum foam is that the initial fatigue crack begins the cell wall, the thinnest position of the cell wall or the intersection of the cell wall and the cell ridge, where stress concentrations are more likely to occur. The fatigue failure of aluminum foam core usually starts from the semi-closed unit of the lower layer, and the fatigue crack propagates layer by layer along the direction of the maximum shear stress. The results can provide a reference for the practical engineering design and application of AFSP.

• Korean Journal of Environmental Biology
• /
• v.29 no.1
• /
• pp.23-30
• /
• 2011

In this study, the Comet assay (evaluation of DNA damage) used the fish hepatocellular carinoma cell, PLHC-1, was tried to the sediment extract obtained from freshwater to understand its applicability as a tool for monitoring sediment toxicity. In parallel, induced EROD (7-ethoxyresorufin- O-deethylase) activity and DNA damage (TEM values) in PLHC-1 cells were measured for establishing the tandem endpoints of the PLHC-1cell test to test the ecotoxicity of sediment. Among several study sites in a small river passed through downtown and industrial park area, one of them, site B, showed a higher level of EROD activity and DNA damage than other sites. It indicates that a tandem endpoints of PLHC-1 cells could be useful tools for assessing the toxicity of sediment. The sensitivity of Comet assay with PLHC-1 cells was a little higher than that with a blood cell of frog tadpoles to the solvent extract of sediment. According to the results, a PLHC-1 cell-Comet assay could be used as a useful tool for evaluating ecotoxicity of the freshwater sediment. In addition, more detailed studies are needed to the contaminated site.

• Animal cells and systems
• /
• v.16 no.1
• /
• pp.20-26
• /
• 2012

Drug-induced parkinsonism has been associated with an increased risk for Parkinson's disease. Antipsychotic drugs have long been known to cause parkinsonian symptoms. However, it remains unclear whether antipsychotics can directly damage the nigrostriatal pathway. In the present study, we investigated the toxicity mechanism of two typical antipsychotics, perphenazine and trifluoperazine, in a human dopaminergic cell line, SH-SY5Y. Perphenazine and trifluoperazine induced mitochondrial damage as evidenced by fragmentation of mitochondria, activation of Bax, cytochrome c release and a decrease in cellular ATP level. In addition, activation of caspase-3 and apoptotic nuclei were observed following the drug treatment. However, pan-caspase inhibitor did not suppress the cell death induced by the antipsychotics, suggesting that the initiated apoptosis was possibly shifted to necrosis upon caspase inhibition. Damaged mitochondria may have induced oxidative stress since the drug-induced cell death was partially suppressed by an antioxidant. Taken together, our results suggest that perphenazine and trifluoperazine can induce apoptotic cell death in a dopaminergic cell line via mitochondrial damage accompanied by oxidative stress.

• Journal of the Semiconductor & Display Technology
• /
• v.13 no.2
• /
• pp.29-35
• /
• 2014

In this study general solar cell production process was complemented, with research on improvement of solar cell efficiency through surface structure and thermal annealing process. Firstly, to form the pyramid structure, the saw damage removal (SDR) processed surface was undergone texturing process with reactive ion etching (RIE). Then, for the formation of smooth pyramid structure to facilitate uniform doping and electrode formation, the surface was etched with HND(HF : HNO3 : D.I. water=5 : 100 : 100) solution. Notably, due to uniform doping the leakage current decreased greatly. Also, for the enhancement and maintenance of minority carrier lifetime, antireflection coating thermal annealing was done. To maintain this increased lifetime, front electrode was formed through Au plating process without high temperature firing process. Through these changes in two processes, the leakage current effect could be decreased and furthermore, the conversion efficiency could be increased. Therefore, compared to the general solar cell with a conversion efficiency of 15.89%, production of high efficiency solar cell with a conversion efficiency of 17.24% was made possible.

• Korean Journal of Plant Resources
• /
• v.22 no.6
• /
• pp.489-497
• /
• 2009

In this study, we evaluated and compared the protective effects of two major constituents, baicalein and baicalin, against oxidative DNA and cell damages caused by hydroxyl radical. Antioxidant properties were evaluated using DPPH and hydroxyl radicals scavenging assays and $Fe^{2+}$ chelating assay. ${\varphi}X$ 174 RFI plasmid DNA and intracellular DNA migration assay were used to evaluate the protective effect against oxidative DNA damage. Also, MTT and lipid peroxidation assays were used to evaluate their protective effects against oxidative cell damage. Both baicalein and baicalin prevented intracellular DNA and cells from oxidative damage caused by hydroxyl radical via antioxidant activities. Baicalein demonstrated a stronger antioxidant activity in scavenging DPPH radicals and chelating $Fe^{2+}$ while baicalin scavenged hydroxyl radicals more efficiently. The differences in the level of baicalein and baicalin pose a different pathological pathway for each. The antioxidant activity of baicalin was due to its ability to scavenge hydroxyl radical whilst baicalein was a stronger $Fe^{2+}$ chelator. Further investigation to compare the molecular mechanisms of antitumor activities of baicalein and baicalin is vital to anticancer research.

• The Korea Journal of Herbology
• /
• v.29 no.5
• /
• pp.91-95
• /
• 2014

Objectives : This study was carried out to evaluate whether the water extract from cause the cellular damage in HepG2 cell line. It was reported that Dictamnus dasycarpus Turcz(DDT) intake induce poisoning symptoms in human population. These symptoms was closely related to liver toxicity, however, mechanisms for liver toxicity caused by DDT have not been elucidated exactly. Here, hepatotoxicity caused by DDT was evaluated using HepG2 cell line. Methods : Water extract of DDT was treated into HepG2 cell with various doses such as 0, 0.1, 0.5, 1.0 and $5.0mg/m{\ell}$. In order to cell viability, both MTT and LDH assay were carried out. Also, apoptosis array kit was used to identify whether cell death caused by DDT is due to apoptosis or not. In addition, reactive oxygen species (ROS) was measured after treatment of water extract. Results : We found out significant changes in the apoptosis related factors of hepatocyte. The cell viability of HepG2 treated with DDT water extract was decreased in dose-dependent. Also most of the apoptosis related factors were significantly increased. We found out that Caspase 3, Cytochrome C and ROS had increased in dose-dependent. In addition, other apoptosis related factors Bcl 2 and Bax, which were also constant changes. However, there was no significance. Conclusions : These results suggest that water soluble extract of DDT is expected to have oral toxicity, including hepatocellular damage Therefore, it is suggested that DDT could cause various side effects and toxicity of clinical conditions.