• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.2
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• pp.184-189
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• 2016

We investigated physiological changes in the freshwater cichlid, fish Maylandia lombardoi in response to different calcium concentrations in rearing water. Four different calcium concentrations (0, 2, 4 and 8 mM) were prepared in rearing water by the addition of ionized calcium (CaO) to examine the effect of various calcium concentrations in rearing water on physiological changes in the cichlid fish, M. lombardoi. Total calcium concentrations in plasma and body increased in a calcium concentration-dependent manner and reached the maximum at 8-mM calcium concentration. Stress-related cortisol was significantly decreased in the 8-mM group compared to the control group (0 mM). Lysozyme activity also significantly decreased in the 8-mM group. These results suggest that CaO in rearing water increases calcium uptake in fish and affects the body by decreasing stress and improving immunity in fish.

• Clinical and Experimental Reproductive Medicine
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• v.19 no.1
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• pp.15-29
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• 1992

In the present study, it was aimed to find the role of calcium on the maturation of mouse follicular oocytes as well as for the role of calcium inhibitors, $Ni^{2+}$ and $La^{3+}$. Mouse follicular oocytes were cultivated in different media at $37^{\circ}C$, in 100% humidified $CO_2$ incubator for 3 and 17 hrs. The results were as follows; 1. There was no differences in GVBD between the control and experimental groups during the 3 hr culture. 2. Mouse oocytes were matured to higher rate in MHBS rather than HTF for 17 hr culture. 3. Maturation rate was significantly lower in $Ca^{2+}$-free and $Ca^{2+}$ 0.4 mM which were tested, compared to other calcium concentration used in the present study. 4. Calcium inhibitor, $Ni^{2+}$, it showed highest degeneration rate at all calcium concentrations and additionally in $Ni^{2+}$ $100{\mu}M$ treated group next. Maturation rate was significantly decrease as the $Ca^{2+}$ inhibitor concentration increased. 5. In all Lanthanum treated groups of calcium-free, degeneration were significantly high treated groups at 0.4 mM $Ca^{2+}$ concentrations degeneration rates of all group were significantly lower than that of the control but maturation rates were not significantly different in any group. In lanthanum $100{\mu}M$ treated group at 0.4 mM and 0.8 mM calcium concentration, its maturation rate was significantly higher than that of the control. Maturation rates of all groups of lanthanum treated at 1.71 mM calcium concentration were not significantly different among groups. 6. In the calcium treated group (0.4mM-1.7 mM), the presence of phosphate does not seem to be needed for oocyte maturation. However, the presence of phosphate at $Ca^{2+}$ 0.8 mM only seems to stimulated maturation.

• Journal of Nutrition and Health
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• v.34 no.5
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• pp.532-540
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• 2001

This study explored the effect of calcium levels and/or ovariectomy on bone composition and its related factors using the female Sprague-Dawley rats which achieved peak bone mass in normal(0.5%) calcium intake during growth period. The rats were randomly divided into six groups and fed 0.1%, 0.5% and 1.5% calcium diets for 8 weeks after ovariectomized and sham operation. The results indicated that body weight gain was higher in ovariectomized groups than sham groups, regardless of dietary calcium levels and food intakes. Serum Ca and P concentrations were normal level regardless of dietary calcium levels and operation. Estrogen concentration was decreased in ovariectomized rat groups. Serum alkaline phosphatase activity and urinary hydroxyproline were increased in ovariectomized groups. When rats were fed normal Ca diet during growing period, weight, length and breaking force of femur were not significantly different in all groups but increased the same level. Generally, lipid contents in lumbar and femur were lower in low calcium groups and this effect was more pronounced in femur. In case of femur, the significant decrease in Ca contents of bone was observed in a relatively short period of feeding low Ca diet, even though it appeared th desirable peak bone mass had achieved through the growing period by supplementing the adequate amount of calcium. The marked decrease of estrogen levels after ovariectomy did not seem to influence greatly bone parameters measured except bone wet weight. Therefore, this study indicated that lower intake of Ca might be more important determinating factor against osteoporosis than postmenopausal state stimulated by ovariectomy in female rats. With normal or high intake of Ca it appears possible to prevent bone loss in postmenopausal period, and this might apply only in case of achieving peak bone mass in the growing with the adequate intake of calcium. (Korean J Nutrition 34(5) : 532∼540, 2001)

• Journal of Korean Dental Science
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• v.10 no.2
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• pp.45-52
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• 2017

Calcium has versatile roles in diverse physiological functions. Among these functions, intracellular $Ca^{2+}$ plays a key role during the secretion of salivary glands. In this review, we introduce the diverse cellular components involved in the saliva secretion and related dynamic intracellular $Ca^{2+}$ signals. Calcium acts as a critical second messenger for channel activation, protein translocation, and volume regulation, which are essential events for achieving the salivary secretion. In the secretory process, $Ca^{2+}$ activates $K^+$ and $Cl^-$ channels to transport water and electrolyte constituting whole saliva. We also focus on the $Ca^{2+}$ signals from intracellular stores with discussion about detailed molecular mechanism underlying the generation of characteristic $Ca^{2+}$ patterns. In particular, inositol triphosphate signal is a main trigger for inducing $Ca^{2+}$ signals required for the salivary gland functions. The biphasic response of inositol triphosphate receptor and $Ca^{2+}$ pumps generate a self-limiting pattern of $Ca^{2+}$ efflux, resulting in $Ca^{2+}$ oscillations. The regenerative $Ca^{2+}$ oscillations have been detected in salivary gland cells, but the exact mechanism and function of the signals need to be elucidated. In future, we expect that further investigations will be performed toward better understanding of the spatiotemporal role of $Ca^{2+}$ signals in regulating salivary secretion.

• Journal of Nutrition and Health
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• v.44 no.2
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• pp.101-111
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• 2011

It is controversial whether low calcium intake, commonly associated with osteoporosis, results in calcium accumulation in soft tissues. This study was conducted to investigate the effects of low calcium (Ca) and oxalate (ox) intake on soft-tissue Ca deposits and bone metabolism in ovariectomized (ovx) rats. Eight week old female Sprague-Dawley rats were ovariectomized and divided into four groups. The rats were fed experimental diets containing low (0.1%, w/w) or normal (0.5%, w/w) Ca with or without sodium oxalate (1%, w/w); Sham/NCa, Ovx/NCa, Ovx/LCa, Ovx/NCa-ox, Ovx/LCa-ox for 6 weeks. All ovx rats showed a remarkable increase in body and tissue weight, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, blood urea nitrogen, alkaline phosphatase, and decreases in weight, ash, and Ca contents, as well as bone breaking force compared to those in sham rats. Serum Ca concentration was not significantly affected by dietary Ca levels or ox intake. Kidney Ca, ox acid content, and microscopic Ca deposition increased remarkably in the Ovx/LCa-ox group compared to those in the other groups. Ca content in the spleen and aorta also increased significantly, but the weight contents, Ca, bone breaking force, and Ca and oxalic acid in feces decreased significantly in the Ovx/LCa-ox group. Serum parathyroid hormone levels were not significantly different among the groups. These results indicate that low Ca intake decreased bone mineral content and increased Ca deposits in soft tissues, which was aggravated by ox intake in ovx rats. Thus, high ox intake may result in a kidney disorder in patients with osteoporosis who eat a low Ca diet.

• Journal of Ceramic Processing Research
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• v.20 no.6
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• pp.655-659
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• 2019

Calcium phosphates such as HA (hydroxyapatite), β-TCP (tricalcium phosphate) and biphasic HA/β-TCP, were synthesized by wet chemical precipitation in aqueous solution combined with ball milling process. Nanosize powders of the calcium phosphates were synthesized using Ca(OH)2 and H3PO4. The effects of initial precursor Ca/P ratio (1.30, 1.50 and 1.67), ball milling process and post heat-treatment on the phase evolution behavior of the powders were investigated. The phase of resulting powder was controllable by adjusting the initial Ca/P ratio. HA was the only phase for as-prepared powders in both cases of Ca/P ratios of 1.50 and 1.67. The single HA phase without any noticeable second phase was obtained for the initial Ca/P ratio of 1.67 in the overall heat-treatment range. Pure β-TCP and biphasic calcium phosphate (HA/β-TCP) were synthesized from precursor solutions having Ca/P molar ratios of 1.30 and 1.50, respectively, after having been heat-treated above 700 ℃. The β-TCP phase has appeared on the pre-existing DCPD (dicalcium phosphate dihydrate) and/or HA phase. Dense ceramics having translucency were obtained at a considerably lower sintering temperature. The modified process offered a fast, convenient and economical route for the synthesis of calcium phosphates.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.12
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• pp.1706-1710
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• 2011

An experiment was conducted to investigate the effects of calcium (Ca) fertilization on oxalate content in napiergrass (Pennisetum purpureum) and on some blood parameters of sheep. Re-growth napiergrass was grown with or without Ca fertilizer and offered to sheep. Eight sheep, divided into two groups of 4 animals each were used. Calcium-fertilized napiergrass was offered daily to the animals as experimental treatment, whereas without Ca-fertilized napiergrass was given to the animals as control. Results showed that there was a trend to lower soluble and total oxalate concentrations in Ca-fertilized grass than control. The Ca-fertilized grass contained (p<0.05) lower concentrations of K and Mg than control, though Ca fertilization had no affect (p>0.05) on Ca and Na concentrations in plants. Feeding of Ca-fertilized grass had no affect on the feed consumption, blood Mg level and daily gain of sheep. However, sheep fed control grass had lower (p<0.05) blood Ca level than sheep fed Ca-fertilized grass. Our findings suggest that Ca fertilization might minimize the negative effects of oxalate.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.567-576
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• 2014

This study investigated the physiological effects of a diet containing calcium oxide (CaO) on the olive flounder, Paralichthys olivaceus. The results indicate that the amount of calcium in the blood was higher in the calcium group compared with the controls. The aspartate amino transferase (AST) and alanine amino transferase (ALT) levels were lower in the calcium group, while lysozyme activity was higher in the calcium group. Histologically, fish in the calcium group had more hepatocytes in the liver and more intact scales. In addition, an attack experiment using Vibrio anguillarum (KCTC-2711) and Edwardsiella tarda (KCTC-3657) showed that the survival was higher in the calcium group compared with the controls. These results suggest that feeding fish CaO when they require it, such as during periods of gonadal maturation and rapid growth, will increase their immunity and resistance to pathogens.

• Journal of the Korean Society for Heat Treatment
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• v.15 no.6
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• pp.260-268
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• 2002

The effects of calcium and silicon on microstructure and aging characteristics of AZ91 magnesium alloy during T5 treatment was investigated. The addition of 0.88% calcium or 0.25% silicon to AZ91 alloy made dendrite cell smaller. Especially, silicon is more effectively acted as refinement of the dendrite cell than calcium. It is due to that $Mg_2Si$ precipitated at the dendrite cell boundary or in the matrix during T5 treatment of Si added AZ91 alloy retarded the growth of the secondary phase. In the mean while, without inducing the precipitates containing calcium, calcium was segregated mainly around secondary phase such as $Mg_{17}Al_{12}$ and partially dissolved in ternary eutectic (Mg-Al-Ca) structure. In the AZ91 alloy containing both silicon and calcium, more finely distributed $Mg_2Si$ in matrix homogeneously and much finer microstructure were obtained than those containing silicon or calcium. Hence, An AZ91 containing both silicon and calcium was more effective to retarding the growth of the secondary phase than the other AZ91 alloy such as AZ91 alloy containing silicon or AZ91 alloy containing calcium.

• Journal of Nutrition and Health
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• v.43 no.1
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• pp.12-25
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• 2010

This study was carried out to evaluate the bioavailabilities and the digestibilities of oligopeptide chelated (peptide-Ca), anchovy bone (anchovy-Ca) and methionine hydroxyl analogue (MHA-Ca) calcium compared to those of calcium carbonate in rats. In exp1, $CaCO_3$, were added to the basal diet at level of 0, 30 and 60% calcium of the AIN-93G diet. In test groups, peptide-Ca, anchovy-Ca and MHA-Ca, were added to the basal diet to provide calcium at the level of 40% of AIN-93G. In exp1, the bioavailabilities were evaluated from the regression equation of the ratios of theological/ actual calcium intakes of each dietary treatment. In exp2, urine and feces was to evaluate the true- and apparent digestibility and apparent retention. In exp1, Ca-60% group had higher bone mineral density (BMD), bone mineral content (BMC) and bone breaking strength (BBS) than those of the other standard groups. The bone weight and ash content of the peptide-Ca and anchovy-Ca groups were significantly higher than those of the MHA-Ca. Bone calcium content were not significantly different from the test group. The bioavailability of the MHA-Ca group was shown higher BMD (71%), BS (38%) and BBS (27%) compared to another control group. But the regression coefficient for BMD, BS and BBS were lower compare with that of bone ash and BMC. In exp2, the true- and apparent digestibility of test groups were shown to over 90%. Peptide-Ca was not significantly different from other test group, but digestibility and retention were higher compare to other test groups. In conclusion, peptide-Ca, anchovy-Ca and MHA-Ca improved Ca bioavailability in the rats. The compounds were higher Ca digestibility compared with those of $CaCO_3$. It is assumed that difference of digestibility for test groups may be correlated to the bioavailability of test groups in BMD, BMC, BS, BBS and bone ash respectively.