• Korean Journal of Soil Science and Fertilizer
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• v.39 no.2
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• pp.80-85
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• 2006

The foliar injuries and absorption rates of calcium compounds in tomato (Lycopersicon esculentum cv. momotaro) and citrus [Shiranuhi(C. Marc. ${\time}C$. sinensis Osbeck)${\time}C$. reticulata Blanco)] were investigated. 0.3, 0.5 and 1.0% of $CaCl_2$, $Ca(NO_3)_2$, $Ca(H_2PO_4)_2$, Ca-EDTA, Ca formate or Ca acetate solution were applied to the leaves of tomato and citrus. The leaf burns were observed only in the foliar applications of Ca-EDTA and $Ca(H_2PO_4)_2$. Ca-EDTA exhibited more serious foliar injury than CaH2PO4. As applied with $^{45}CaCl_2$, $^{45}Ca(NO_3)_2$, $^{45}Ca$ formate or $^{45}Ca$ acetate, the rates of Ca absorptions by tomato and citrus leaves for 7 days were 17 to 32% and 6.6 to 46%, respectively. It meant that the absorption was differently influenced on calcium compounds. In tomato, the order of Ca foliar absorption was $Ca(NO_3)_2$ > Ca formate = $CaCl_2$ > Ca acetate. Although there was no difference in Ca absorption between the adaxial and abaxial parts of tomato leaves, total absorption was greater in expanded leaves than in expanding ones. On the other hand, in citrus Ca foliar absorption from $Ca(NO_3)_2$ or Ca formate was more active than that from $CaCl_2$ or Ca acetate. In conclusion, $Ca(NO_3)_2$ and Ca formate are recommended for the foliar application of Ca in tomato and citrus in order to increase absorption of Ca into their leaves.

• Journal of Biosystems Engineering
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• v.40 no.1
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• pp.78-88
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• 2015

Purpose: The objective of this study is to review researches regarding factors that potentially affect adolescent calcium (Ca) metabolism, and to suggest a potential modeling approach for optimizing gastrointestinal Ca absorption and peak bone mass. Background: Optimal gastrointestinal Ca absorption is a key to maximizing peak bone mass in adolescents. Urine Ca excretion in adolescents rises only after bone accretion is saturated, indicating that higher intestinal Ca absorption and bone retention is necessary to ensure maximum bone accretion. Hence, maximizing peak bone mass is possible by controlling the factors influencing gastrointestinal Ca absorption and bone accretion. However, a mechanism that explains the unique adolescent Ca metabolism has not yet been elucidated. Review: Dietary factors that enhance gastrointestinal Ca absorption may increase the available Ca pool usable for bone accretion, and a specific hormone may direct optimal Ca utilization to maximize peak bone mass. IGF-1 is an endocrine hormone whose levels peak during adolescence and increase fractional Ca absorption and bone Ca accretion. Prebiotics, generally obtained from dietary sources, have been reported to exert a beneficial effect on Ca absorption via microbiota activity. We selected and reviewed three candidates that could be used to propose a comprehensive Ca metabolic model for optimal Ca absorption and peak bone mass in adolescents. Modeling: Modeling has been used to investigate Ca metabolism and its regulators. Herein, we reviewed previous Ca modeling studies. Based on this review, we proposed a method for developing a comprehensive model that includes regulatory effectors of IGF-1 and prebiotics.

• Journal of Nutrition and Health
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• v.26 no.2
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• pp.154-154
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• 1993

A factorial experiment was conducted to determine the influence of phytate(0 or 10g/kg diet) and calcium (Ca)(3 or 10g/kg diet) intakes on Ca, P and Zn metabolism by growing female rats. Food intake and weight were similar for the all groups, however, phytate ingestion for six weeks depressed femur growth. The low Ca plus phytate group showed the lowest Ca content of total femur and this was related to a significant decrease of Ca retention. Phytate intake depressed zinc(Zn) absorption in the first metabolic collection. This inhibitory effect of phytate on Zn absorption was improved in the low Ca plus phytate group after several weeks. Impared Zn absorption however remained in the high Ca plus phytate group which was reflected in the lowest Zn content of femur, phytate intake with high Ca also depressed phosphorous(P) absorption and serum and urinary P. These adverse effects of phytate on Zn and P absorption when the dietary Ca was high could explain reduced femur weight despite the highest concentration of femur Ca(mg/g ash) in this group. Results suggest that phytate can adversely affect not only Ca metabolism but Zn and P utilization. Thus, for the normal bone growth when phytate intake is high, the ingesion of Ca, P, Zn and other minerals should be enhanced.

• Journal of Food Hygiene and Safety
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• v.18 no.2
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• pp.73-78
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• 2003

This study was to investigate interaction between ionization rate and absorption rate of calcium(Ca) in each feeding Ca sources in rats. The results were as follows. 1. The ionized Ca ions 134 into rats were absorbed in about two hours while Ca from other sources like powdered egg-shell Ca or precipitable Ca carbonate caused more than five hours to be absorbed. This means that the ionization of Ca is essential for the fast absorption in rat. 2. Absorption rate were increased in the rank order to brown rice vinegar-Ca acetate > brewed vinegar-Ca acetate > precipitated Ca carbonate > egg-shell Ca powder by feeding sources in rat and absorption rate of brown rice vinegar Ca was appeared 4 times highly than egg-shell Ca powder. 3. Absorption rate of brewed vinegar Ca acetate were appeared excellent, 1.4 times highly in case of the brewed vinegar at no ventilation condition than ventilation condition. 4. Ca concentration in blood serum was significantly enhanced the increased ionization rate of Ca in the above experiment rat models regardless of dietary Ca levels.

• The Korean Journal of Community Living Science
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• v.16 no.1
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• pp.135-148
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• 2005

This study was conducted to investigate the bioavailability of calcium derived from starfish as a new calcium source. Four-week old Sprague-Dawley female rats were divided 6 groups. The rats were received experimental diets containing two kinds of Ca sources, CaCO₃ or starfish, and three levels of Ca, low (0.1 %), medium (0.5%) and high (1.0%), respectively, for 6 weeks. The parameters which related to Ca bioavailability were measured : Serum Ca concentration, Alkaline phosphatase(ALP) and GOT activities ; tissue Ca contents, bone dimension and Ca, P, Mg contents; Ca retention and apparent absorption. Starfish Ca-fed rats did not show any difference from CaCO₃-fed rats in terms of growth, food intake and FER. Serum Ca, ALP and GOT activities as well as tissue Ca contents were not different between CaCO₃- and starfish Ca-fed groups. Although dimension of femur and lumbar was not different between CaCO₃- and starfish Ca-fed rats, ash content was high in starfish Ca-fed rats. Ca and P contents of femur and lumbar were not different between both groups. Starfish Ca-fed groups showed higher Mg contents than CaCO₃-fed groups in both femur and lumbar. Ca absorption rate and retention rate were significantly higher in starfish Ca-fed rats. These results indicate that Ca derived starfish did not show any negative effect on growth and Ca metabolism of rats compared to calcium carbonate. Starfish Ca can be recommended as a good Ca source on the basis of higher Ca absorption and bioavailability.

• Journal of Nutrition and Health
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• v.26 no.2
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• pp.145-155
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• 1993

A factorial experiment was conducted to determine the influence of phytate(0 or 10g/kg diet) and calcium (Ca)(3 or 10g/kg diet) intakes on Ca, P and Zn metabolism by growing female rats. Food intake and weight were similar for the all groups, however, phytate ingestion for six weeks depressed femur growth. The low Ca plus phytate group showed the lowest Ca content of total femur and this was related to a significant decrease of Ca retention. Phytate intake depressed zinc(Zn) absorption in the first metabolic collection. This inhibitory effect of phytate on Zn absorption was improved in the low Ca plus phytate group after several weeks. Impared Zn absorption however remained in the high Ca plus phytate group which was reflected in the lowest Zn content of femur, phytate intake with high Ca also depressed phosphorous(P) absorption and serum and urinary P. These adverse effects of phytate on Zn and P absorption when the dietary Ca was high could explain reduced femur weight despite the highest concentration of femur Ca(mg/g ash) in this group. Results suggest that phytate can adversely affect not only Ca metabolism but Zn and P utilization. Thus, for the normal bone growth when phytate intake is high, the ingesion of Ca, P, Zn and other minerals should be enhanced.

• Journal of Biosystems Engineering
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• v.38 no.2
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• pp.129-137
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• 2013

Purpose: Modeling has been used for elucidating the mechanism of complex biosystems. In spite of importance and uniqueness of adolescent calcium (Ca) metabolism characterized by a threshold Ca intake, its regulatory mechanism has not been covered and even not proposed. Hence, this study aims at model-based proposing potential mechanisms regulating adolescent Ca metabolism. Methods: Two different hypothetic mechanisms were proposed. The main mechanism is conceived based on Ca-protein binding which induces renal Ca filtration, while additional mechanism assumed that active renal Ca re-absorption regulated Ca metabolism in adolescents. Mathematical models were developed to represent the proposed mechanism and simulated them whether they could produce adolescent Ca profiles in serum and urine. Results: Simulation showed that both mechanisms resulted in the unique behavior of Ca metabolism in adolescents. Based on the simulation insulin-like growth factor-1 (IGF-1) is suggested as a potential regulator because it is related to both growth, a remarkable characteristic of adolescence, and Ca metabolism including absorption and bone accretion. Then, descriptive modeling is employed to conceptualize the hypothesized mechanisms governing adolescent Ca metabolism. Conclusions: This study demonstrated that modeling is a powerful tool for elucidating an unknown mechanism by simulating potential regulatory mechanisms in adolescent Ca metabolism. It is expected that various analytic applications would be plausible in the study of biosystems, particularly with combination of experimental and modeling approaches.

• Journal of Nutrition and Health
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• v.30 no.1
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• pp.40-47
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• 1997

Dietary peptides have recently received attention regarding their beneficial effects on nutrient metabolism since the caseinphosphoptides obtained from casein hydrolysate are generally believed to enhance the intestinal absorption of Ca. The two experiments were conducted to investigate the effects of various hydrolyzed fractions of gluten on Ca bioavailability. The gluten hydrolysate of dietary components was produced by enzymatic hydrolysis of gluten whereas gluten hydrolysate supernationt and its precipiate resulted from centrifugation. In experiment I, the rats were for 4 weeks fed the 4 kinds of diets containing same amount of nitrogen and calories and diffeing only in the forms of nitrogen sources. The diets were gluten (G), gluten hydrolysat(GH), gluten hydrolysate supernatant(GHS) and gluten hydrolysate precipitatie(GHP). Determination was made for the body weight gain, serum Ca concentration, Ca solubility in small intestinal contents, bone weight, length and stength, bone ash and Ca content, and Ca balance, respectively. No significant difference was noticed as regards growth, serum Ca, and bone dimension and Ca content among rat groups. More significant increase was observed with regard to Ca absorption and intestinal solubility in the rats receiving the GH or GHS diet which containe crude gluten peptides, than in those subjected to G or GHP diet. In experiment II, in vitro determination for Ca solubility was made to ascertain the mechanism responsible for the effects of gluten peptides on Ca absorption. The 10mM Ca in potassium phosphate buffer solution(pH 7.0) incubated for 3 hours at 37$^{\circ}C$ by the GHS fraction, was observed to be capable of increasing the Ca solubility at 5-25mg/ml concentration of gluten peptides. These observations suggest that the gluten peptides from gluten hydrolysate may enhance the Ca absorption efficiency by increasing the solubility of Ca in small intestine.

• Journal of Plant Biology
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• v.39 no.3
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• pp.173-177
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• 1996

A novel calcium binding protein (CaBP) was purified to electrophoretic homogeneity from Dunaliella salina. In the course of purification experiment, this CaBP was identified as a monomer and its molecular weight was about 21 kDand isoelectric point (pI) value was about 4.1 using isoelectrofocusing. This CaBP was able to bind Ca2+ even in the pressence of an excess MgCl2 and KCI both in solution. In the SDS-PAGE, the Ca2+-bound form was slower than the Ca2+-free form in the nondenaturing PAGE. This means that the CaBP undergoes conformational change in the Ca2+-bound condition. Furthermore, UV absorption spectrum and fluorescence intensity of this CaBP was investigated. UV absorption peak was appeared at about 258 nm and decreased somewhat in Ca2+-bound condition. In the measurement of fluorescence, maximum intensity was appeared at 303 nm and decreased in Ca2+-bound state, similarly as UV absorption spectrum. These show distinct changes upon Ca2+-binding, which indicate of structural and/or dynamic changes largely reminiscent of other members of the EF-hand Ca2+-binding protein family.

• Journal of Nutrition and Health
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• v.12 no.1
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• pp.17-22
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• 1979

This study was designed to investigate calcium intake, the ratio of Ca intake versus R.D.A. (Recommended Dietary Allowance) for Ca, apparent Ca absorption rate, and Ca sources of food among school children in Korea. One hundred school children aged from 6 to 12 years were engaged in this study; 33 subjects were from farming village neal Seoul, and 67 children from big cities. Two days of food consumption records and feces collections of the subjects had been done from April 1978 to June 1978. The following observations were made in the present study; 1) Average Ca intake of total subjects was $457{\pm}214mg$ which is only 76% of R.D.A. for Ca. Calcium intakes for farming village children was higher than that of the subjects from big cities (p<0.05). 2) Survey on the food sources of Ca revealed that the amount of Ca taken from cereals averaged 120 mg (22.3% of total Ca intake), 111 mg (24.3%) from fruits and vegetables, 176 mg (38.5%) from meats, poultry, fishes and eggs, and only 68 mg (14.9%) was supplied by milk and milk products. From the data collected, following observations were made; a) No significant difference in Ca intake from cereals was found between village children and the ones from big cities. b) Average Ca intake from fruits and vegetables of city children was significantly higher than that of village children (p<0.005) with the values for 133 mg for the former and 64 mg for the latter. c) For the group of meats, poultry, fishes and eggs, significantly higher intake was found in village subjects than city children (p<0.0005) with the values of 340 mg and 95 mg, respectively. d) Contrarily, Ca intake from milk and milk products was significantly (p<0.0005) much higher in the city children (98 mg) than village ones (7 mg). 3) Apparent Ca absorption rate of total subjects was 51%; 44% for village children and 54% for city children. Ca absorption rate tends to be higher in the city subjects but no significant difference was noted.