• Journal of Nutrition and Health
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• v.32 no.6
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• pp.726-731
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• 1999

Many studies show that the bone loss in postmenopausal women is closely related with status of vitamin K. The purpose of this study is to observe the effects of the vitamin K supplements on the carboxylation of serum osteocalcin in postmenopausal women. Twenty-four healthy postmenopausal women were recruited for the double-blind controlled study. Before and after daily administration of 1.0mg of phylloquinone for one month, the levels of serum vitamin K, osteocalcin, undercarboxylated osteocalcin were measured. Daily intake of vitamin K was also calculated. After the 4-weeks of supplements of 1.0mg/day of vitamin K, there were no significant differences for the levels of serum vitamin K, osteocalcin, and ucOC between the experimental and placebo groups. In this study, it was not found that the supplements of vitamin K to the postmenopausal women had any positive effects on.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.878-882
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• 2007

Carboxylated multi-walled carbon nanotubes (MWNTs) were in detail characterized by XRD, XPS, FTIR, and thermogravimetric measurements. Carboxylic acid groups were functionalized to MWNTs under aqueous acid condition. The changes of sonication and reflux conditions rarely influenced the degree of carboxylation on MWNTs, but decreased the thermal stability of the resultant carboxylated MWNTs. XRD results showed that the diffraction peaks (100), (101), and (102) of pristine MWNTs disappeared after acid treatment, but the diffraction peak (002) was Preserved in the carboxylated MWNTs. The introduction of carboxylic acid groups on MWNTs caused to improve the dispersibility of the resultant carboxylated MWNTs in water.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.565-568
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• 2013

Acetyl-CoA carboxylases (ACCs) play critical roles in fatty acid synthesis and oxidation by the catalytic activity of the carboxylation of acetyl-CoA to malonyl-CoA. It is known that ACCs are inactivated through reversible phosphorylation by AMP-activated protein kinase (AMPK) and allosterically activated by citrate. Here, we determined the crystal structures of biotin carboxylase (BC) domain of human ACC2 phosphorylated by AMPK in the presence of citrate in order to elucidate the activation mechanism by citrate. This structure shows that phosphorylated Ser222 is released from the dimer interface, and thereby facilitating the dimerization or oligomerization of the BC domain allosterically. This structural explanation is coincident with the experimental result that the phosphorylated Ser222 was dephosphorylated more easily by protein phosphatase 2A (PP2A) as the citrate concentration increases.

• Journal of Korean society of Dental Hygiene
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• v.11 no.4
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• pp.419-426
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• 2011

Originally, vitamin K was defined as a factor for blood coagulation. Now more attention is focused on vitamin K for bone metabolism and bone health. Vitamin K is a coenzyme for glutamate carboxylase which converts glutamate residues to ${\gamma}$-carboxyglutamate(Gla) residues. Gla residues have calcium binding ability and bound to hydroxyapatite crystals in bone. Vitamin K promotes the carboxylation of osteocalcin and matrix Gla-protein, vitamin K-dependent proteins and improves bone mineral density and bone mass. Vitamin K deficiency causes reductions in bone mineral density and increases the risk of osteoporotic bone fractures, resulting from undercarboxylated osteocalcin. This paper is to provide a brief information of vitamin K and its role in bone health.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.63-63
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• 2007

Carboxylated multi-walled carbon nanotubes (MWNTs) were in detail characterized by XRD, XPS, FTIR, and thermogravimetric measurements. Carboxylic acid groups were functionalized to MWNTs using aqueous acid solutions. The change. of sonication and reflux conditions rarely influenced the degree of carboxylation on MWNTs, but reduced the thermal stability of the resulting carboxylated MWNTs. The characteristic Bragg peaks of pristine and carboxylated MWNTs were analyzed by XRD measurements. After acid treatment the diffraction peaks (100), (101), and (102) of pristine MWNTs disappeared, but the diffraction peak (002) was preserved in the carboxylated MWNTs. The introduction of carboxylic acid groups on MWNTs caused to improve the dispersibility of the resulting carboxylated MWNTs in water.

• Korean Journal of Exercise Nutrition
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• v.16 no.1
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• pp.1-9
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• 2012

Long chain fatty acids (LCFAs) are transported into cells via plasma transporters, are activated to fatty acyl-CoA by fatty acyl-CoA synthase (ACS), and enter mitochondria via the carnitine system (CPT1/CACT/CPT2). The mitochondrial carnitine system plays an obligatory role in β-oxidation of LCFAs by catalyzing their transport into the mitochondrial matrix. Fatty acyl-CoAs are oxidized via the β-oxidation pathway, which results in the production of acetyl-CoA. The acetyl-CoA can be imported into the tricarboxylic acid (TCA) cycle for oxidation in the mitochondrial matrix or can be used for malonyl-CoA synthesis by acetyl-CoA carboxylase 2 (ACC2) in the cytoplasm. In skeletal muscle, ACC2 catalyzes the carboxylation of acetyl-CoA to form malonyl-CoA, which is a potent endogenous inhibitor of carnitine palmitoyltransferase 1 (CPT1). Thus, ACC2 indirectly inhibits the influx of fatty acids into the mitochondria. Fatty acid metabolism can also be regulated by malonyl-CoA-mediated inhibition of CPT1.

• Journal of Korean Society of Forest Science
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• v.96 no.5
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• pp.551-560
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• 2007

We investigated physiological damages and biochemical alleviation of five species of genus Acer under ozone fumigation in order to assess their tolerant ability against ozone toxicity. At the end of 150 ppb $O_3$ fumigation, photosynthetic characteristics were measured, and chlorophyll contents, malondialdehyde (MDA) and antioxidative enzyme activities were analyzed in the leaves of five maple trees (Acer buergerianum, A. ginnala, A. mono, A. palmatum, and A. palmatum var. sanguineum). The reduction of chlorophyll (chl) a in ozone-exposed plants was 16.8% (A. buergerianum) to 26.7% (A. ginnala) of control plants. For the content of chi b, A. ginnala and A. palmatum var. sanguineum represented the high reduction of 26.3% and 23.6%, respectively. The highest reduction on the chi a:b ratio was observed in the leaves of A. palmatum. The reduction of net photosynthesis in five species varied from 2.4% to 37.6%. Among five species, A. ginnala showed remarkable reduction (37.6%) for net photosynthesis in comparison with control. Carboxylation efficiency differed significantly (P < 0.05) among species and between control and ozone treatment. The reduction of carboxylation efficiency was the highest in the leaves of A. ginnala (44.7%). A. palmatum var. sanguineum showed the highest increase (41.7%) for MDA content. The highest increase of superoxide dismutase (SOD) activity represented in A. palmatum (26.1%) and the increase of ascorbate peroxidase (APX) activity ranged from 16.5% (A. ginnala) to 49.1% (A. palmatum var. sanguineum). A. mono showed the highest increase (376.6%) of glutathione reductase (GR) activity under ozone fumigation and A. buergerianum also represented high increase (42.3%) of GR activity. Catalse (CAT) activity increased in the leaves of A. ginnala, A. palmatun and A. palmatum var. sanguineum under ozone exposure, whereas A. buergerianum and A. mono decreased in comparison with control plants. In conclusion, physiological markers such as chlorophyll content and photosynthesis that responded sensitively to $O_3$ in maple trees were considered as the very important indicators in order to evaluate the tolerance against $O_3$ stress, and parameters were closely related with each other. Among anti oxidative enzymes, SOD and APX might be contributed to alleviate to $O_3$ toxicity through the increase of activity in all maple trees. Therefore, these compounds can be used as a biochemical maker to assess the stress tolerance to $O_3$.

• Journal of Korean Society of Forest Science
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• v.97 no.5
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• pp.508-515
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• 2008

Sycamore (Platanus occidentalis L.) seedlings were grown under low light intensity and ozone treatments to investigate the role of the light environment in their response to chronic ozone stress. One-year-old seedlings of Platanus occidentalis L. were grown in pots for 3 weeks under low light (OL, $150{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and high light (OH, $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) irradiance in combination with 150 ppb of ozone fumigation. After three weeks of ozone and light treatment, seedlings were placed in ozone free clean chamber for 3 weeks for recovery from ozone stress with same light conditions to compare recovery capacity. Ozone fumigation determined an impairment of the photosynthetic process. Reduction of leaf dry weight (14%) and shoo/root ratio (17%) were observed in OH treatment. OL treatment also showed severe reductions in leaf dry weight and shoot/root ratio by 48% and 36% comparing to control, respectively. At the recovery phase, OH-treated plants recovered their biomass, whereas OL-treated plant showed reduction in leaf dry weight (52%) and shoot/root ratio (49%). OH-treated plants reached similar relative growth rate (RGR) comparing to control, whereas OL-treated plants showed lower RGR in stem height. However, there were no significant differences in response to those treatments in stem diameter RGR at the recovery phase. Ozone treatment produced significant reduction of net photosynthesis in both high and low light treatments. Carboxylation efficiency and apparent quantum yield in OL-treated plants showed significant reductions rate to 10% and 45%, respectively. At the recovery stage, ozone exposed seedlings under high light had similar photosynthetic capacity comparing to control plants. Antioxidant enzymes activities such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR) were increased in ozone fumigated plants only under low light. The present work shows that the physiological changes occur in photosynthesis-related parameters and growth due to ozone and low light stress. Thus, low light seems to enhance the detrimental effects of ozone on growth, photosynthesis, and antioxidant enzyme responses.

• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.2
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• pp.47-57
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• 2008

Physiological and biochemical changes of five species of genus Quercus exposed to ozone fumigation were investigated to assess their tolerance against ozone toxicity. At the end of 150 ppb ozone fumigation, chlorophyll contents, photosynthetic characteristics, malondialdehyde(MDA) and antioxidative enzyme activities were measured in the leaves of five Quercus species(Quercus acutissima, Q. aliena, Q. palustris, Q. serrata, and Q. variabilis). Chlorophyll and carotenoid contents, net photosynthesis and carboxylation efficiency decreased after ozone treatment, indicating that $O_3$-exposed plants underwent physiological inhibition. The reduction rate of total chlorophyll contents and carboxylation efficiency were respectively 15% and 34% for Q. aliena and 38% and 62% for Q. variabilis. The amount of MDA increased with the highest increase rate of 140% in Q. acutissima which also showed the highest increase rate(60%) of superoxide dismutase(SOD). Ascorbate peroxidase(APX) activity increased in Q. variabilis, Q. serrata and Q. acutissima by ozone treatment. Based on our results, ozone tolerance of the five Quercus species was ranked as Q. aliena>Q. palustris>Q. serrata>Q. variabilis>Q. acutissima. We concluded that chlorophyll contents, photosynthesis, MDA content and antioxidative enzymes were the important physiological markers for tolerance against ozone stress, which were closely related with one another.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.4
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• pp.353-359
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• 1988

Variations in photosynthetic capacities of leaves differing in thickness were explained on the basis of relationships between gas exchange and internal leaf structure. The relative importance of gas diffusion and of biochemical processes as limiting for leaf photosynthesis was also determined. Mesophyll cell surface was considered to be the limiting internal site for gas diffusion. and cell volume to be indicative of the sink capacity for CO$_2$ fixation. Increases in cell surface area were assumed to reduce proportionately mesophyll resistance to the liquid phase diffusion of CO$_2$. Increased cell volume was thought to account for a proportional increase in reaction rates for carboxylation, oxygenation. and dark respiration. This assumption was tested using chamber-grown Glycine max (L.) Merr. cv. Amsoy plants. Plants were grown under 200, 400, and 600 ${\mu}$mol photons m$\^$-2/ s$\^$-1/ of PAR to induce development of various leaf thickness. Photosynthetic CO$_2$ uptake rates were measured on the 3rd and 4th trifoliolate leaves under 1000 ${\mu}$mol photons m$\^$-2/ s$\^$-1/ of PAR and at the air temperature of 28 C. A pseudo -mechanistic photosynthesis model was modified to accommodate the concept of cell surface area as well as both cell volume and surface area. Both versions were used to simulate leaf photosynthesis. Computations based on volume and surface area showed slightly better agreement with experimental data than did those based on the surface area only. This implies that any single factor, whether it is photosynthetic model utilized in this study was suitable for relating leaf thickness to leaf productivity.