• Bulletin of the Korean Chemical Society
• /
• v.32 no.1
• /
• pp.273-276
• /
• 2011

Uniform Ag nanoparticles (< 10 nm) were effectively prepared in 1-amino-4-methylpiperazine as a solvent with multiple functions including reduction and stabilization. An Ag-complex such as $Ag_2(ehac)_2(eha)_2$ (ehac = 2-ethylhexylammonium carbamate; eha = 2-ethylhexylamine) was used as an Ag-precursor, whereas the usage of a salt such as $AgNO_3$ showed the formation of Ag nanoparticles in larger and irregular size (30 - 500 nm). The Ag nanoparticles (< 10 nm) prepared by using the Ag-complex could also be effectively stabilized by 1-amino-4-methylpiperazine. Transmission electron micrographs confirmed that the Ag particles were spherical and in the nanometer size.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.47 no.6
• /
• pp.465-470
• /
• 2021

Few cases of spontaneous bone regeneration after extensive resection of the jaw bone have been reported, but it is more common in young adults or children. In this case, we report spontaneous bone healing in a 73-year-old female patient. On radiological examination, necrotic regions were seen in the right mandible. She was diagnosed with medication-related osteonecrosis of the jaw due to previous bisphosphonate use. After segmental resection, stabilization achieved using a reconstruction plate. The periosteum was preserved during the procedure. Twelve months later, panoramic radiography was taken and bone formation was seen both horizontally and vertically around the plate. If the periosteum is preserved and stabilization is achieved after resection in benign lesions, the bone may regenerate spontaneously regardless of age. Therefore, instead of simultaneous autogenous bone application, such patients may be followed to determine whether spontaneous bone healing will occur. This should improve patient comfort and reduce surgical cost.

• Proceedings of the Korean Environmental Health Society Conference
• /
• 2004.12a
• /
• pp.51-62
• /
• 2004

Lime based stabilization/solidification (S/S) can be an effective remediation alternative for the immobilization of arsenic (As) in contaminated soils and sludges. However, the exact immobilization mechanism has not been well established, Based on previous research, As immobilization could be attributed to sorption and/or inclusion in pozzolanic reaction products and/or the formation of calcium-arsenic (Ca-As) precipitates. In this study, suspensions of lime-As were studied in an attempt to elucidate the controlling mechanism of As immobilization in lime treated soils. Aqueous lime-As suspensions (slurries) with varying Ca/As molar ratios (1:1, 1.5:1, 2:1, 2.5:1 and 4:1) were prepared and soluble As concentrations were determined. X-ray diffraction (XRD) analyses were used to establish the resulting mineralogy of crystalline precipitate formation. Depending on the redox state of the As source, different As precipitates were identified. When As (III) was used, the main precipitate formation was Ca-As-O. With As(V) as the source, Ca4(OH)2(AsO4)2${\cdot}$4H2O formed at Ca/As molar ratios greater than 1:1. A significant increase in As (III) immobilization was observed at Ca/As molar ratios greater than 1:1. Similarly, a substantial increase in As (V) immobilization was noted at Ca/As molar ratios greater than or equal to 2.5: 1. This observation was also confirmed by XRD. The effectiveness of both As (III) and As(V) immobilization in these slurries appeared to increase with increasing Ca/As molar ratios.

• Molecules and Cells
• /
• v.42 no.11
• /
• pp.773-782
• /
• 2019

Cellular senescence is an irreversible form of cell cycle arrest. Senescent cells have a unique gene expression profile that is frequently accompanied by senescence-associated heterochromatic foci (SAHFs). Protein kinase CK2 (CK2) downregulation can induce trimethylation of histone H3 Lys 9 (H3K9me3) and SAHFs formation by activating SUV39h1. Here, we present evidence that the PI3K-AKT-mTOR-reactive oxygen species-p53 pathway is necessary for CK2 downregulation-mediated H3K9me3 and SAHFs formation. CK2 downregulation promotes SUV39h1 stability by inhibiting its proteasomal degradation in a p53-dependent manner. Moreover, the dephosphorylation status of Ser 392 on p53, a possible CK2 target site, enhances the nuclear import and subsequent stabilization of SUV39h1 by inhibiting the interactions between p53, MDM2, and SUV39h1. Furthermore, $p21^{Cip1/WAF1}$ is required for CK2 downregulation-mediated H3K9me3, and dephosphorylation of Ser 392 on p53 is important for efficient transcription of $p21^{Cip1/WAF}$. Taken together, these results suggest that CK2 downregulation induces dephosphorylation of Ser 392 on p53, which subsequently increases the stability of SUV39h1 and the expression of $p21^{Cip1/WAF1}$, leading to H3K9me3 and SAHFs formation.

• Animal cells and systems
• /
• v.6 no.3
• /
• pp.263-269
• /
• 2002

The p53 tumor suppressor gene is among the most frequently mutated and studied genes in human cancer, but the mechanisms by which it sur presses tumor formation remain unclear. DNA damage regulates both the protein levels of p53 and its affinity for specific DNA sequences. Stabilization of p53 in response to DNA damage is caused by its dissociation from Mdm2, a downstream target gene of p53 and a protein that targets p53 for degradation in the proteosome. Recent studies have suggested that phosphorylation of human p53 at Ser20 is important for stabilizing p53 in response to DNA damage through disruption of the interaction between Mdm2 and p53. We generated mice with an allele encoding changes at Ser20, known to be essential for p53 accumulation following DNA damage, to enable analyses of p53 stabilization in vivo. Our data showed that the mutant p53 was clearly defective for full stabilization of p53 in response to DNA damage. We concluded that Ser20 phosphorylation is critical for modulating the negative regulation of p53 by Mdm2, probably through phosphorylation-dependent inhibition of p53-Mdm2 interaction in the physiological context.

• Korean Journal of Microbiology
• /
• v.31 no.4
• /
• pp.318-325
• /
• 1993

The optima] conditions for the formation, the regeneration. and the spheroplast fusion of Flavimonas aryz/habitans spheroplasts were investigated. Cells were transformed to spherop]asts effectively by treatment of 0.5% volume (v/v) of 0.] M EDTA and ]00 flg/ml lysozyme at $37^{\circ}C$ for 30 min without shaking. Magnesium chloride and calcium chloride were effective on the stabilization of spheroplasts. and 20 mM calcium chloride in the rich regeneration medium improve the yield of regenerants as much as 3.5-fo]d. Addition of 0.8% bovine serium albumine (BSA) in dilution buffer for spheroplast formation improved the stabilization of spheroplasts over extended periods (4-6 hr) at room temperature. and thus increased the yield of recombinants to 4.5-fold. The spheroplast formation frequency and regeneration frequency of F aryzihabitans strain was 90.10% and 3.800/." respectively. The first regenerated cell of F. aryzihabitans spheroplasts were appeared 6 hours after plating. By I I hours after plating, 80% of spheroplasts were regenerated on thc rich regeneration medium containing 0.5 M sucrose. The intraspeci11c spheroplast fusion of F urvz/habitans was carried out and the properties of obtained fusants were investigated. Formation of fusion products was effective when the Flav/munas spheroplast mixture was treated with 40%(w/v) PEG6000 and 20 mM CaCl, for 10 min at room temperature. and thc formation of frequency of recombinants were $2.0{\times}10^{-5}~3.6{\times}10^{-5}$. All tested recombinant clones were very stable on further propagation.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.982-985
• /
• 2007

The authors report methods of fabrication singlelayer color cholesteric liquid crystal displays (CLCDs). A single-layer CLCD has been prepared from a polymerstabilized cholesteric liquid crystal. The unique feature of the polymer stabilization is in that the electrically switched colors preserve high reflectivity. A bistable single-layer CLCD has been prepared by the formation of polymer barrier walls and light-tuned cholesteric pitches to reflect blue, green and red color sub-pixels.

• Bulletin of the Korean Chemical Society
• /
• v.15 no.1
• /
• pp.12-14
• /
• 1994

p-Fluorophenyl bicyclo[3.2.l]oct-6-en-2-yl cation (3) prepared in $FSO_3H-SO_2-CIF$ solution at -90$^{\circ}$C and examined by fluorine-19 nmr spectroscopy. The nmr data give a clear evidence for the formation of a stabilized ${\pi}$-bridging cation species in superacids. The degree of ${\pi}$delocalization in this cation is found to be inferior to the onset of nonclassical stabilization in 2-norbornenyl cation.

• Journal of Periodontal and Implant Science
• /
• v.33 no.1
• /
• pp.91-102
• /
• 2003

Several effective treatment methods and materials have been developed for the treatment of furcation involvement. Currently, the combination of guided tissue regeneration (GTR) and bone grafts is the most commonly prescribed method of treating furcation involved defects. But because these cases often present with poor accessibility, placement of the membrane may be difficult and consequently, clinically impractical. In this study, the alveolar bone healing patterns of adult beagle dogs presenting with alveolar bone destruction treated by one of two methods - treatment using solely bone allografts (BBP(R)), or treatment using bone allografts (BBP(R)) stabilized by a fibrin adhesive - were comp ared. The effects of the fibrin adhesive on the initial stabilization of the newly formed bone, subsequent regeneration of bone, and the feasibility of the clinical application of the fibrin adhesive were analyzed. The results of the study were as follows: 1. Clinical signs of inflammation at the 4-8 week interval were not observed: but signs of mild inflammation were histologically observed at the 4-week interval. 2. Allografts stabilized by fibrin adhesive showed good bone formation, whereas defects treated with only the allograft material showed incomplete alveolar bone regeneration. 3. Allografts stabilized by fibrin adhesive showed a decrease in the amount old bone with a concurrent increase in the formation of new lamellar bone four weeks post-op, whereas defects treated with only the allograft material showed no new lamellar bone formation at the same interval. 4. In detects treated with only the allograft material, the defective area was filled with connective tissue 8-weeks post-op, whereas fibrin adhesive stabilized allografts showed viable connections between the original bone and the newly formed bone, in addition to neovascularization 8-weeks post-op. The results of this study show that concurrent use of fibrin adhesive materials can stabilize the allograft material and aid in new bone formation Although the stability of fibrin adhesives fall short of the results achievable by GTR membranes, in cases presenting with poor accessibility that contraindicate the use of membranes, fibrin adhesive materials provide a viable and effective alternative to graft stabilization and new bone formation.

• Journal of the Korean Chemical Society
• /
• v.22 no.1
• /
• pp.7-11
• /
• 1978

The reactions of 2,4-dinitroiodobenzene with para subtituted anilines in acetonitrile-methanol binary solvent mixtures have been studied. Rate constants for reactions in methanol rich solvents are greater than for reactions in acetonitrile rich solvents. Kinetic results show that the bond formation step is rate determining in the solvent system studied. The solvent effect can be explained by stabilization of the transition state by formation of hydrogen bond between oxygen atom of methanol and hydrogen atom of aniline.