• Journal of the Korean Chemical Society
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• v.29 no.3
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• pp.304-310
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• 1985

Effect of spermine on the susceptibility of calf thymus nucleohistone to DNase 1, in relation to the structural change of the nucleohistone, and cooperativity of the interaction of the nucleohistone with DNase 1 was investigated. Dansylated nucleohistone, in which the histone moiety had been derivatized by dansylation, was also used to investigate functional roles of the histone moiety on the cooperativity. The data here indicate the possibility that the nucleohistone, in contrast with the DNA, may not undergo monomolecular condensation, whereas intermolecular aggregation and enhancement of the positive cooperativity of the interaction of nucleohistone with DNase 1 may be brought about by spermine. The interaction of the DNS-nucleohistone with DNase 1 showed negative cooperativity. Based on the data here, it can be speculated that the cooperativity of the nucleohistone is influenced by the histone moiety of the nucleohistone.

• Journal of Microbiology
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• v.40 no.4
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• pp.319-326
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• 2002

Cellular DNA in prokaryotes is organized in nucleic acid-protein self-assemblies referred to as the nucleoid. The physical forces responsible for its stability inside the poor solvent properties of the cytoplasm and their functional implications are not understood. Studies on the organisation and functioning of the cytosol of cells largely rely on experimental protocols performed in highly dilute solutions using biochemically purified molecules, which is not a reliable substitute for the situation existing in vivo. Our current research interest is focused on the characterization of biological and physical forces determining the compaction and phase separation of DNA in Escherichia coli cytoplasm. We have emphasized the effect of excluded volume in solutions with high macromolecular concentrations (macromolecular crowding) upon self-association patterns of reactions. The prokaryotic cytosol was simulated by addition of inert polymer polyethylene glycol (PEG) (average molecular weight 20000), as an agent which afterwards facilitates the self-association of macromolecules. Fluorescence microscopy was used for direct visualization of nucleoids in intact cells, after staining with DAPI (4',6-diamidino-2-phenylindole dihydrochloride). Addition of the crowding agent PEG 20,000, in increasing concentrations generated progressively enhanced nucleoid compaction, the effect being stronger in the presence of 0.2 M NaCl and 5 mM MgCl$\_$2/. Under these conditions, the nucleoids were compacted to volumes of around 2 ㎛$\^$3/ or comparable sizes with that of living cells.

• Biomolecules & Therapeutics
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• v.20 no.5
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• pp.487-491
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• 2012

The aim of this study was to investigate the inhibitory effects of rutaecarpine on DNA strand breaks and apoptosis induced by hydrogen peroxide ($H_2O_2$) in murine Hepa-1c1c7 cells. Oxidative DNA damage was estimated by nuclear condensation assessment, fluorescence-activated cell sorting analysis, and Comet assay. Rutaecarpine inhibited cell death induced by $500{\mu}M$ $H_2O_2$, as assessed by 4',6-diamidino-2-phenylindole (DAPI) staining. Treatment with rutaecarpine reduced the number of DNA strand breaks induced by $H_2O_2$, as assessed by DAPI staining and Comet assay, and increased quinone reductase, phosphatidylinositol 3-kinase, and pAkt protein levels, as assessed by western blotting.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.1
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• pp.20-27
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• 2007

Eugenol is commonly used in dentistry for the sedation of toothache, pulpitis, and dental hyperalgesia. This study was performed to investigate the apoptotic effect of eugenol to human osteosarcoma (HOS) cells and the potential use of this compound in osteosarcoma cells. Eugenol showed the apoptotic effect in HOS cells in dose- and time-dependent manner. Fragmentation and condensation of DNA were showed by TUNEL assay, Hemacolor stain and Hoechst stain. In the DNA electrophoresis analysis, cells showed DNA degradation characteristic of apoptosis with a ladder pattern of DNA fragments. Apoptosis-related factors were analyzed by western blotting. Cells treated with eugenol showed caspase-3, PARP, lamin A and DFF-45 cleavage. Eugenol treatment induced caspase-3 cleavage and activation. Cleavages of PARP, DFF-45 and lamin A were accompanied with activation of caspase triggered by eugenol in HOS cells. Though this study needs more investigations, these results suggest that eugenol induce apoptosis via caspase dependent pathway in HOS cells and eugenol may constitute a potential antitumor compound against osteosarcoma cells.

• Molecular & Cellular Toxicology
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• v.1 no.2
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• pp.73-77
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• 2005

Nickel is the one of potent environmental, the occupational pollutants and the classified human carcinogens. It is a serious hazard to human health, when the metal exposure. To prevent human diseases from the heavy metals, it is seemingly important that understanding of how nickel exerts their toxicity and carcinogenic effect at a molecular and a genomic level. The process of nickel absorption has been demonstrated as phagocytosis, iron channel and diffusion. Uptaked nickel has been suggested to induce carcinogenesis via two pathways, a direct DNA damaging pathway and an indirect DNA damaging pathway. The former was originated from the ability of metal to generate Reactive Oxygen Species (ROS) and the reactive intermediates to interact with DNA directly. Ni-generated ROS or Nickel itself, interacts with DNAs and histones to cause DNA damage and chromosomal abnormality. The latter was originated from an indirect DNA damage via inhibition of DNA repair, or condensation and methylation of DNA. Cells have ability to protect from the genotoxic stresses by changing gene expression. Microarray analysis of the cells treated with nickel or nickel compounds, show the specific altered gene expression profile. For example, HIF-I (Hypoxia-Inducible Factor I) and p53 were well known as transcription factors, which are upregulated in response to stress and activated by both soluble and insoluble nickel compounds. The induction of these important transcription factors exert potent selective pressure and leading to cell transformation. Genes of metallothionein and family of heat shock proteins which have been known to play role in protection and damage control, were also induced by nickel treatment. These gene expressions may give us a clue to understand of the carcinogenesis mechanism of nickel. Further discussions on molecular and genomic, are need in order to understand the specific mechanism of nickel toxicity and carcinogenicity.

• Polymer(Korea)
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• v.31 no.5
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• pp.454-459
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• 2007

Gene therapy using low molecular weight water soluble chitosan (LMWSC) as polycationic polymer shows good biocompatibility, but low transfection efficiency. The mechanism of folic acid (FA) uptake in the cells to promote targeting and internalization could improve transfection rates. The objective of this study was to synthesize and characterize the WSCFA-DNA complex and evaluate their cytotoxicity, in vitro. In $^1H-NMR$ spectra, specific peaks appeared both of FA and LMWSC in $D_2O$. WSCFA nanoparticles have spherical shapes with particle size show below 110 nm. In the cell cytotoxicity test, the WSCFA-DNA complex showed high cell viability, in vitro. Gel electrophoresis showed condensed DNA within the carriers. hi vitro transfection efficiency was assayed by fluorescence spectroscopy WSCFA nanoparticles have less cytotoxicity, good DNA condensation and particle size around 110 nm, which makes them a promising candidate as a non-viral gene vector.

• BMB Reports
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• v.29 no.1
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• pp.27-31
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• 1996

Using topoisomerase II (topo II) isozyme-specific antibodies, we investigated the phosphorylation of topo $II{\alpha}$ in mitotic HeLa cells. Topo $II{\alpha}$ was specifically modified in the mitotic cells, resulting in slow migration on SDS-polyacrylamide gel electrophoresis. To characterize the nature of this modification, we treated the nuclear extracts prepared from the mitotic cells with alkaline phosphatase. After the treatment with alkaline phosphatase, the slowly migrated band disappeared and instead a normal (170 kDa) topo $II{\alpha}$ band appeared. These results indicate that human topo $II{\alpha}$ is modified at a specific site(s) in M phase by phosphorylation, supporting the possibility that M phase-specific phosphorylation of topo II is critical for mitotic chromosome condensation and segregation.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.189-195
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• 2002

The aim of this study was to investigate the action of benzalkonium chloride (BAC) used as a preservative in most ophthalmic topical solutions, on human corneal epithelial (HCE) cells in vitro. HCE cell line was exposed to BAC solutions at various concentrations (0.01%~0.0001%) for 15 minutes followed by 24 hours of cell recovery. Cell viability was assessed using MTT assay and chromatin condensation with a Hoechst 33342 test. The expression of membrane protein Fas and Fas ligand was examined by western blot and immunocytochemistry, and DNA fragmentation was studied by agarose gel electrophoresis. A significant decrease of membrane integrity with chromatin condensation was observed with BAC tested at concentrations of 0.005% and higher. BAC was cytotoxic preservatives in this study. An apoptotic mechanism appeared to be present at low concentrations of BAC, whereas a necrotic process appeared at higher concentrations. A functional Fas-mediated apoptotic pathway is present in cultured HCE cells and can be activated by upregulation of Fas expression with BAC.

• Korean Journal of Biological Psychiatry
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• v.5 no.1
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• pp.66-70
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• 1998

Apoptosis is a form of cell death in which the cells shrink and exhibit nuclear chromatin condensation and DNA fragmentation, and yet maintain membrane integrity. Many lines of evidence have shown that brain neurons are vulnerable to degeneration by apoptosis. Also it has been suggested that apoptosis is one of the mechanism contributing neuronal loss in Alzheimer's disease(AD), since the conditions in the disease($A{\beta}$ peptide, oxidative stress, low energy metabolism) are the inducers that activate apoptosis. Indeed some neurons in vulnerable regions of the AD brain show DNA damage, chromatin condensation, and apoptic bodies. Consistently, mutations in AD causative genes(Amyloid precursor protein, Presenilin-1 and Presenilin- 2) increase $A{\beta}$ $peptide_{1-42}(A{\beta}_{1-42})$ and sensitize neuronal cell to apoposis. However, several lines of evidence have shown that the location of neuronal loss and $A{\beta}$ peptide deposition is not correlated in AD brain and transgenic mice brain over-expressing $A{\beta}_{1-42}$. Taken together, these data may indicated that $A{\beta}$ peptide(and other causative factors of AD) can interact with other cellular insults or risk factors to exacerbate pathological mechansim of AD through apoptosis. Thus, this review discusses possible role and mechanism of apoptosis in AD.

• Journal of Photoscience
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• v.9 no.2
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• pp.454-456
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• 2002

It is important to determine the action spectrum of UV-B radiation contained in the sunlight to estimate the risk of skin cancer. We have investigated action spectra for induction of apoptosis and reproductive cell death in L5178Y cells using the Okazaki Large Spectrograph at NIBB. L5178Y cells were exposed to light at different wavelengths in UV-B or UV-A region. Frequencies of apoptosis induction and reproductive cell death were determined by counting cells with chromatin condensation, and by the colony formation assay, respectively. The measured sensitivity spectra for the two end-points were in very good agreement. Sensitivity decreased steeply with increase of wavelength in UV-B region and remains nearly constant in UV-A region. The action spectra were also slightly steeper than that for the minimum erythematic dose (MED), but very similar to the light absorption spectrum of DNA in UV-B region. On the other hand, the spectra for both endpoints were similar to MED spectrum but not DNA spectrum in the UV-A region. Also different time-course and morphological difference of apoptosis were found between UV-B (long time, fragmentation) and UV-A (short time, shrinkage) region. These results suggest that DNA damage induced by UV-B light triggers apoptosis and reproductive cell death, but other damaged targets (membrane, protein and so on) trigger these effects in UV-A region.