• Journal of Plant Biotechnology
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• v.39 no.1
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• pp.23-32
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• 2012

Calcium is an essential nutrient for living organisms, with key structural and signaling roles. Its deficiency in plants can result in poor biotic and abiotic stress tolerance as well as reduced crop quality and yield. Calcium deficiency in humans causes various diseases such as osteoporosis and rickets. Biofortification of calcium in various food crops has been suggested as an economic and environmentally advantageous method to enhance human intake of calcium. Recent efforts to increase the levels of calcium in food crops have used calcium/proton antiporters ($CAXs$) and modified one to increase calcium transport into vacuoles through genetic engineering. It has been reported that overall calcium content of transgenic plants has been increased in their edible portions with some adverse effects. In conclusion, biofortification of calcium will add more value in crops as well as will be beneficial for animal and human. Therefore, more fundamental studies on the mechanisms of calcium ion storage and transporting are essential for more effective calcium biofortification.

• Environmental Mutagens and Carcinogens
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• v.22 no.4
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• pp.229-235
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• 2002

Thimerosal, a widely used preservative, has been well known to induce intracellular calcium mobilization in various cell types. However, the mechanism of its calcium mobilization is not clearly understood yet. For studying the mechanism of thimerosal-mediated calcium release, we have used HL60 cells in calcium-free Lockes solution that has no extracellular calcium. Thimerosal significantly reduced the lag period of initial calcium release whereas it enhanced the rate and magnitude of the calcium release in a dose-dependent manner. At the same time, we found that thimerosal generated superoxide anion by activating NADPH oxidase in dose- and time-dependent manner. Interestingly, the kinetics and the dosedependency of superoxide anion generation were very similar to those of intracellular calcium mobilization. In inhibitors study, the thimerosal-induced superoxide anion generation was significantly suppressed by DMSO as well as superoxide dismutase but not by genistein or EGTA. Surprisingly, the pretreatment with N-Acetyl-$_{L}$-Cysteine blocked almost completely the thimerosal-induced calcium increase, indicating that ROS playa key role in the calcium mobilization. The present results suggest that thimerosal-induced calcium mobilization is possibly mediated by the activation of NADPH oxidase and subsequent ROS generation.n.

• Journal of Nutrition and Health
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• v.29 no.6
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• pp.590-593
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• 1996

This study was done to evaluate the effect of dietary calcium level (a diet which met 100% or twice the calcium level in AIN-76 diet) on preventing bone loss in ovariectomized rats. Forty Sprauge-Dawley female rats(body weight 200$\pm$5g)were divided into two groups. One group were ovariecotomized (Ovx) while the others received sham operation(Sham). Thereafter, each rat group was further divided into normal calcium diet(0.52%) and high calcium diet(1.04%) subgroups. All rats were fed on experimental diet and deionized water ad libitum for 8 weeks. The total body, spine and femur bone mineral densities and bone mineral contents were measured by Dual Energy X-ray Absorptiometry, Eight weeks following operation, ovariectomized rats fed a high calcium diet had a significantly higher total bone mineral content, total bone calcium content, spine bone mineral density, spine bone mineral content and femur bone mineral content than ovariectomized rats fed control calcium diet. The correlation between dietary calcium intake level and spine bone mineral density were positive, but there was no correlation between dietary calcium intake and femur bone mineral density. The findings from the present study demonstrated that bone loss due to ovarian hormonal deficiency can be partially prevented by a high calcium diet. Futhermore, these findings support the strategy of the use of a high calcium diet in the prevention of estrogen depleted bone loss(postmenopausal osteoporosis)

• Korean Journal of Community Nutrition
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• v.6 no.4
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• pp.628-634
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• 2001

This study was conducted to investigate the relationship of serum calcium and magnesium level to depression and anxiety symptoms in 66 perimenopausal women. Daily nutrient intakes and dietary sources of calcium were analyzed by convenient me쇙. General status was conducted by a questionnaire whereas the questionnaire of CED-S(the Center for Epidemiological studies-Depression Scale) was used for depression and Spielburger's STAI-S(state-Trait Anxiety Inventory-State) was used for anxiety. Fasting blood samples were collected, and serum calcium and magnesium concentrations were measured before and after calcium supplementation. The age distribution of the subjects was 49-55 years. Results indicated that serum calcium concentrations were significantly(P〈0.05) increased to normal ranges after calcium supplementation. Depression and anxiety scores of the subjects with calcium supplementation were significantly(p〈0.05) lower than those before calcium supplementation. There were significantly(P〈0.05) decreased between serum magnesium concentration and depression and anxiety scores, but calcium concentration was not significantly decreased. These results suggest that psychological conditions of perimenopausal women are possibly effected by serum calcium and magnesium levels. More studies are needed to measure the long-term effects of calcium supplementation on psychological conditions in perimenopausal women.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.6
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• pp.1016-1023
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• 1996

The effect of dietary calcium levels, 50%, 100%, and 200% of requirement, on iron utilization was evaluated in 30 Sprague-Dawley female rats by use of balance study for 3 weeks. In the results of this study, there were no significant difference in feed intake, body weight gain, hemoglobin level, hematocrit, calcium and iron levels in serum and tissues across the groups supplemented different calcium levels. Calcium content in kidney of high-calcium group was significantly higher than that of other groups. Urinary and fecal calcium excretions increased as the level of dietary calcium was increased. With increasing levels of dietary calcium, daily calcium retention was accelerated, but daily calcium retention rate was diminished. Iron intake was significantly higher in adequate-calcium group than that in low-calcium or high-calcium group. Urinary and fecal iron excretions were significantly lower in low-calcium group than those in adequate-calcium or high-calcium group. Apparent retention and retention rate estimated by intake, urinary and fecal excretions of iron were significantly lower in high-calcium group t]lan those in low-calcium or adequate-calcium group. These results suggest that taking dietary calcium supplements reduce the absorption of dietary iron.

• International Journal of Oral Biology
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• v.30 no.1
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• pp.9-15
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• 2005

Recently, we reported that high extracellular calcium increased receptor activator of nuclear factor-${\kappa}B$ ligand (RANKL) expression via p44/42 mitogen-activated protein kinase (p44/42 MAPK) activation in mouse osteoblasts. However, the mechanism for p44/42 MAPK activation by high extracellular calcium is unclear. In this study, we examined the role of intracellular calcium increase in high extracellular calcium-induced RANKL induction and p44/42 MAPK activation. Primary cultured mouse calvarial osteoblasts were used. RANKL expression was highly induced by 10 mM calcium treatment. Ionomycin, a calcium ionophore, also increased RANKL expression and activated p44/42 MAPK. U0126, an inhibitor of MEK1/2, an upstream activator of p44/42 MAPK, blocked the RANKL induction by both high extracellular calcium and ionomycin. High extracellular calcium increased the phosphorylation of proline-rich tyrosine kinase 2 (Pyk2), one of the known upstream regulators of p44/42 MAPK activation. Bisindolylmaleimide, an inhibitor of protein kinase C, did not block RANKL induction and p44/42 MAPK activation induced by high extracellular calcium. 2-Aminoethoxydiphenyl borate, an inhibitor of inositol 1,4,5-trisphosphate (IP3) receptor, blocked the RANKL induction by high extracellular calcium. It also partially suppressed the activation of Pyk2 and p44/42 MAPK. Cyclosporin A, an inhibitor of calcineurin, also inhibited high calcium-induced RANKL expression in dose dependent manner. However, cyclosporin A did not affect the activation of Pyk2 and p44/42 MAPK by high extracellular calcium treatment. These results suggest that 1) the increase in intracellular calcium via IP3-mediated calcium release is necessary for RANKL induction by high extracellular calcium treatment, 2) Pyk2 activation, but not protein kinase C, following the increase in intracellular calcium might be involved in p44/42 MAPK activation, and 3) calcineurin-NFAT activation by the increase in intracellular calcium is involved in RANKL induction by high extracellular calcium treatment.

• Journal of Nutrition and Health
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• v.31 no.3
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• pp.279-288
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• 1998

This study explored the effect of calcium levels and/or ovariectomy on bone metabolism using female Sprague-Dawley weanling rats as a model . Rats received a low (0.1%) calcium diet for 8 weeks. The rats were then divided into three subgroups that were fed 0.1% ,0.5% and 1.5% calcium diets for 8 weeks after operation. The results of this experiment indicate that body weight gin was higher in ovariectomy groups than in sham groups regardless of calcium level and food intake. Serum Ca and P concentrations were of normal level regardless of calcium level and ovariectomy. Estrogen concentration was low in the ovariectomized group. Serum alkaline phophatase activity and urinary hydroxyproline have been used as markers of bone formation and resorption. These values were increased in ovariectomized groups. The weight, length and breaking force of femur were not significantly different between the groups. Ash, Ca, P and total lipid contents in femur and lumbar were decreased in the groups fed low calcium . Mg content was decreased in the ovariectomy and total protein content was not affected by calcium level and ovariectomy. The effect groups of ovarectomy on calcium contents of bone was more prominent in lumbar than in femur. In conclusion, though low calcium intakes during growth period may retard the attainment of peak bone mass, calcium supplementation after this period increased bone growth and mineral contents, but not significant effect in three calcium levels. Furthermore, calcium intake was shown to have a greater influence on the mineral contents of femur than of lumbar, and removal of endogenous estrogen production by ovariectomy was shown to be more deleterious on the ash and calcium contents of the lumbar than of femur.

• Nutrition Research and Practice
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• v.9 no.5
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• pp.530-538
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• 2015

BACKGROUND/OBJECTIVES: Calcium is important but deficient in diets of young adult women. This study aimed to examine if cognitive factors and eating behaviors differ according to calcium intake based on the Social Cognitive Theory. SUBJECTS/METHODS: Subjects were female college students in Seoul, Korea. Three hundred students completed the questionnaire regarding calcium intake, nutrition knowledge, outcome expectations, self-efficacy and eating behaviors. Data on 240 students were analyzed using t-test or ${\chi}^2$-test. Subjects were categorized into two groups, high calcium intake (HC, ${\geq}650mg/day$) and low calcium intake (LC, < 650 mg/day), according to recommended intakes of calcium for women aged 19-29 years. RESULTS: The LC group constituted 77.9% of total subjects. Nutrition knowledge was not different according to calcium intake. Three out of 12 outcome expectations items were significantly different between the HC and LC groups. Subjects in the HC group agreed more strongly with the practical benefits of consuming calcium-rich foods, including 'taste' (P < 0.01) and 'going well with other snacks' (P < 0.05), compared to those in the LC group. Negative expectations of 'indigestion' were stronger in the LC group than HC group (P < 0.001). Among self-efficacy items, perceived ability of 'eating dairy foods for snacks' (P < 0.001), 'eating dairy foods every day' (P < 0.01), and 'eating calcium-rich side dishes at meals' (P < 0.05) differed significantly between the HC and LC groups. Eating behaviors including more frequent consumption of dairy foods, fruits or fruit juice (P < 0.001), anchovy, seaweeds, green vegetables, protein-rich foods (P < 0.05), and less frequent consumption of sweets or soft drinks (P < 0.01) were significantly related to calcium intake. CONCLUSIONS: This study found that outcome expectations, self-efficacy in consuming calcium-rich foods, and eating behaviors are important in explaining calcium intake. Nutrition education needs to address practical benefits, reduce negative expectations of calcium-rich foods, increase self-efficacy, and modify eating behaviors contributing to calcium intake.

• Journal of Nutrition and Health
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• v.31 no.1
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• pp.102-107
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• 1998

This study was conducted to investigate the relationship of serum calcium and magnesium levels to depression and anxiety symptoms in 80 homemarker. Fasting blood samples were collected and serum calcium and magnesium concentrations were measured. At the same time, psychological conditions of subjects were estimated by questionnaire. As the result of psychological test, eighty homemarkers were divided into two groups according to psychologicaltest scores. The subjects in one group got high pssycholgoical test scores as high score group (HSG) and the others got low physchological test scores as low score group(LSG). Serum calcium and magnesium concentrations were significantly(p<0.05) lower in HSG than in HSG than in LSG. Many a subject who belonged to HSG appeared to have depression and anxiety symptoms. Drepression and anxiety scores of the subjects with calcium supplementation were significantly (p<0.05) lower than those without calcium supplementation . After calcium supplementation, depressiion and anxiety scores were significantly (p<0.05) decreased in HSG and serum calcium and magnesium concentrations in HSG were significantly increased to normal ranges . This results suggested that psychological conditions of homemarkers might be affected by serum calcium and magnesium levels.

• Journal of Nutrition and Health
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• v.28 no.2
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• pp.144-151
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• 1995

This study investigates the supplementing effects of milks by various heat treatment on growth performance and protein and calcium metabolism of rats. For 4 weeks, raw, LTLT-HTST-and UHT-processed milks were given to rats which fed on a calcium free, semi-synthetic diet containing 5%casein. There were no significant differences among the experimental groups in weight gain, feed efficiency ratio and the serum level of total protein and calcium. Also, no significant differences were showed in protein efficiency, nitrogen balance, apparent protein digestibiltiy and the contents of weight and calcium of the left femur as well as 2 incisors. However, the biological value of protein in the UHT-milk group was significantly higher than that of the raw-milk group. The apparent calcium digestibility and calcium balance in the UHT-milk group were higher than those in the raw-, LTLT- and HTST-milk groups. The weight of left femur in all the groups supplemented with various heat-treated milks was significantly impair the nutritive value of protein and calcium in milk. Futhermore, UHT-processing may improve the bioavailability of protein and calcium in milk.