• Journal of Nutrition and Health
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• 제33권2호
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• pp.147-157
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• 2000

This study examined the effects of excess intake of calcium (Ca) and iron (Fe) supplement on bone loss, nephrocalcinosis and renal function in osteoporotic model rats. Seven-week-old female rats were first fed a Ca-deficient diet for four weeks after ovariectomy operation, and then one of nine experimental diets for additional eight weeks, containing three levels of Ca, normal (0.5%) or high (1.5%) or excess (2.5%) and three levels of Fe, normal (35ppm) or high (210ppm) or excess (350ppm). The osteoporotic model rats showed a remarkable increase in body weight, serum alkaline phosphatase (ALP) and decrease in breaking force, Ca, P, Mg contents of femur. Serum Ca concentration was not significantly affected by dietary Ca and Fe levles. Liver Ca content increased in rats fed a high-and excess-Ca diet. Kidney Ca content and microscopic Ca deposition remarkably increased in osteoporotic model rats compared to control group, and showed a tendency to decrease in rats fed a excess-Ca diet. Breaking force of femur increased with increasing dietary Ca levels, but Ca, P contents of femur and serum ALP were not significantly affected by dietary Ca and Fe levels. Serum total protein decreased in rats fed a excess-Ca diet, BUN increased in rats fed a excess-Ca diet, while serum uric acid and creatinine were not significantly affected by dietary Ca levels. Urinary creatinine, GFR increased in rats fed a high-and excess-Ca, diet, and GFR was highest in rats fed a excess-Ca/excess-Fe diet. These results suggest that excess intake of Ca may increase breaking force of femur, but not increase mineral contents of femur, and decrease kidney function. Furthermore, excess intake of Fe and Ca concurrently may aggravate kidney function leading to potential health problems in ovariectomized osteoporotic model rats.

• 대한지역사회영양학회지
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• 제5권2호
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• pp.243-252
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• 2000

This study examined the effects of excess intake of calcium(Ca) and iron(Fe) supplements on iron bioavailability, liver and kidney functions in anemic model rats. Seven-week-old female rats were first fed and Fe-deficient diet for ten weeks, and then fed one of nine experimental diets for an additional eight weeks, containing three levels of Ca, normal (0.5%) or high(1.5%) or excess (2.5%) and three levels of Fe, normal(35ppm) or high(210 ppm) or excess(350ppm). In anemic model rats, serum Fe, total iron binding capacity(TIBC), hemogolin(Hb), hematocrit(Hct) and liver Fe contents were significantly decreased. Apparent Fe absorption significantly increased with increasing dietary Fe levels, and decreased with increasing dietary Ca levels. serum Fe concentration significantly increased in rats fed a high- and excess-Fe diet, and decreased in rats fed a excess-Ca diet. TIBC was decreawed in rats fed a excess-Ca diet, and transferrin saturation(%) increased in rats fed ahigh- and excess-Fe diet. Hb and Hct were decreased in rats fed an excess-Ca diet regardless of dietary Fe levels. Fe and thiobarbituric acid reactin gsubstance(TBARS) Contents of liver significantly increased in rats fed a high- and excess0-Fe diet, and decreased in rats fed a high- and excess-Ca diet. Fe content of the spleen showed similar results. Urinary creatinine and GFR increased in rats fed an excess-Ca diet regardless of dietary Fe levels. GOT, GPT and LDH were not significantly affected by dietary Ca and Fe levels. These results suggest that excess intake of Fe may increase liver Fe deposits and TBARS, and excess intake of Ca may decrease Fe bioavailability and kidney function leading to potential health problems in anemic model rats.

• Asian-Australasian Journal of Animal Sciences
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• 제12권1호
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• pp.49-55
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• 1999

The effect of fat supplementation of high calcium (Ca) diets on the performance, intestinal pH, body composition and size and weight of organs in growing chickens were investigated in two experiments. Growing chickens tolerated a high dietary level of Ca (22.5 vs 12.1 g/kg) in the presence of 6.3 g/kg of available phosphorus without any significant effect on performance. Intestinal pH was significantly increased by the addition of excess Ca and fat which probably created the right pH for the formation of insoluble Ca soaps. Excess dietary Ca increased carcass linoleic acid concentration at the expense of palmitic and stearic acid contents, whilst the addition of sunflower oil (80 g/kg diet) to the diet increased carcass linoleic acid concentration at the expense of palmitic acid content of the carcass. Intestinal and visceral organ size and weight were not influenced by excess Ca or fat. However, there was a non significant increase in the intestinal dry weight per unit of length caused by excess dietary Ca. It was concluded that excess dietary Ca of 22.5 g/kg did not significantly influence the performance of meat chickens. However, excess Ca increased intestinal pH and altered carcass fatty acid composition. Fat supplementation did not alter intestinal pH with high Ca diets. Excess dietary fat altered carcass fatty acid composition and reduced protein content. Intestinal and visceral organ size and weights were not influenced by excess dietary levels of Ca of fat.

• Journal of Nutrition and Health
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• 제37권8호
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• pp.645-654
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• 2004

This study examined the effect of excess calcium (Ca) on the iron (Fe) bioavailability and bone growth of marginally Fe deficient animals. Two groups of weanling female SD rats were fed either normal Fe (35 ppm) or Fe deficient diet (8 ppm) for 3 weeks. Then each group of animals were assigned randomly to one of three groups and were fed one of six experimental diets additionally for 4 weeks, containing normal (35 ppm) or low (15 ppm) Fe and one of three levels of Ca as normal (0.5%), high (1.0%), or excess (1.5%). Feces and urine were collected during the last 3 days of treatment. After sacrifice blood, organs, and femur bone were collected for analysis. Final body weight and average food intake were not affected by either the levels of dietary Ca or Fe. Low Fe diet significantly reduced the level of serum ferritin, however, for Hb, Hct, and TIBC no difference was shown than those in the normal Fe group. TIBC increased slightly by high and excess Ca intake in low Fe groups. For both normal and low Fe groups, high and excess Ca intakes reduced the apparent absorption of Fe and Fe contents of liver significantly (p < 0.05). Calcium contents in kidney and Femur of rats that were fed high and excess levels of Ca were significantly greater than those of normal Ca groups. However, weight, length, and breaking force of the bone were not affected by increased Ca intakes. Both in control and low Fe groups, high and excess intakes of Ca decreased the apparent absorption of Ca. These results indicate that the excess intakes of calcium than the normal needs would be undesirable for Fe bioavailability and that the adverse effects be more serious in marginally iron deficient growing animals. In addition bone growth and strength would not be favorably affected by high Ca intakes, though, the long term effect of increased Ca contents in bone requires further examination.

• 대한약리학회지
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• 제27권2호
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• pp.167-181
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• 1991

Adenylate cyclase 효소를 활성화시키는 약물인 Forskolin의 흰쥐 적출관류 부신으로부터 Ach, excess $K^+$, McN-A-343 및 caffein에 의한 catecholamines (CA) 분비작용에 대한 영향을 검색하고, 그 기전을 규명코자 연구를 시행하여 다음과 같은 연구결과를 얻었다. Forskolin (1.0 uM)은 흰쥐 부신적출정맥내로 1분동안 관류시킨 후 Ach(50 ug), excess $K^+$(56 mM), DMPP (100 uM) 및 caffeine (0.3 mM)에 의한 CA 분비작용을 현저히 증강시켰으나 McN-A-343에 의한 CA분비작용에는 영향을 미치지 않았다. Forskolin 자체는 CA분비작용을 일으키지 못하였다. 또한 세포의 calcium을 제거한 상태에서도 위 약물에 의한 CA분비작용에 대하여 유의한 증강작용을 나타내었다. 그러나 McN-A-343의 CA작용에는 영향이 없었으나 위의 약물의 CA분비작용을 유의하게 강화시켰다. Cyclic AMP를 증가시키는 약물로 알려져 있는 dibutyryl cyclic AMP (DBcAMP)는 300 uM농도를 1분간 관류시 Ach, excess $K^+$ 및 DMPP의 CA 분비작용을 뚜렷하게 증강시켰으나 McN-A-343 및 caffeine의 CA분비에는 별다른 영향이 없었다. DBcAMP 자체도 CA분비작용에는 영향을 미치지 못하였으나 또한 DBcAMP는 세포의 칼슘제거시에도 위의 약물에 의한 CA분비작용을 의의있게 증강시켰다. 그렇지만, McN-A-343의 CA분비작용은 증강시키지 못하였다. 이상의 연구결과로 보아 Forskolin는 adenylate cyclase를 활성화 시킴으로써 cyclic AMP 농도를 증가시켜 세포내로 칼슘유입을 증강시키며, 또한 세포내의 칼슘이동에도 관여함으로써 cholinergic nicotinic stimulation 및 depolarization에 의한 CA분비작용을 상승시키는 것으로 사료되어진다.

• 한국재료학회지
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• 제2권3호
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• pp.207-212
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• 1992

과잉의 CaO와 $TiO_2$를 각각 포함한 $CaTiO_3$의 결함구조를 평형상태의 전기전도도를 $85O^{\circ}C$와 $1050^{\circ}C$사이에서 산소분압의 함수로 측정하여 연구하였다. 과잉의 CaO는 A site와 B site에 나누어져서 용해되어 $Ca_{Ti}$"와 Vo", 결함을 생성하였으며, 과잉의 $TiO_2$는 $V_{Ca}$"과 Vo"을 생성했다. 평형상태의 전기전도도는 CaO 용해도 5000ppm과 $TiO_2$ 용해도 2000ppm을 각각 나타냈다. 과잉의 양이온에 의하여 생성된 산소공공은 이온전도를 하여 넓은 영역의 산소 분압에 무관한 전도도 최소값을 보였으며, 반대로 대전된 음이온 결함과 결함쌍은 관찰되지 않았다.온 결함과 결함쌍은 관찰되지 않았다.

• 한국재료학회지
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• 제16권2호
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• pp.92-98
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• 2006

Molecular dynamics simulations were performed to study interface structures between an $Al_2O_3$ crystalline phase and a interface phase of $CaAl_2Si_2O_8$. We calculated atomic structures and excess interface energies in systems with different thicknesses of the interface film. It was found that excess interface energies at first readily decreased with increasing film thickness, but increased for larger thicknesses of more than 2 nm. The excess energies of $Al_2O_3/CaAl_2Si_2O_8$ interfaces exhibit a minimum at a thickness around 1 nm. In this range of film thicknesses, the atoms in the interface film show a short-range ordered structure and slow diffusion rather than the random structure and rapid diffusion expected to an observation of an equilibrium thickness for interface films in ceramics.

• 한국세라믹학회지
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• 제30권7호
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• pp.527-534
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• 1993

The phenomena that excess sulfate hindred the C3S formation in the presence of clinker liquid phase were investigated. In the case of (NH4)2SO4, assuming SO3 atmospheric condition, sulfate stabilized C2S and was enriched at the surface of C2S grains, so C2S was prevented from being dissolved into clinker melt. CaSO4 showed the similar aspect with (NH4)2SO4, however, the prevention of C3S formation by CaSO4 took more influence that C2AS and C4A3 were formed below 100$0^{\circ}C$, and remained upto clinkering temperature, 145$0^{\circ}C$, thus these intermediate phases caught CaO which would participate the C3S formation.

• The Korean Journal of Physiology and Pharmacology
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• 제2권2호
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• pp.173-184
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• 1998

The present study was undertaken to examine the influence of glucocorticoids on the secretory responses of catecholamines (CA) evoked by acetylcholine (ACh), DMPP, McN-A-343, excess K^+$ and Bay-K-8644 from the isolated perfused rat adrenal gland and to clarify the mechanism of its action. The perfusion of the synthetic glucocorticoid dexamethasone (10-100\;{\mu}M$) into an adrenal vein for 20 min produced a dose-dependent inhibition in CA secretion evoked by ACh (5.32 mM), excess K^+$ (a membrane-depolarizor 56 mM), DMPP (a selective nicotinic receptor agonist, 100\;{\mu}M$ for 2 min), McN-A-343 (a muscarinic receptor agonist, 100\;{\mu}M$ for 4 min), Bay-K-8644 (a calcium channel activator, 10\;{\mu}M$ for 4 min) and cyclopiazonic acid (a releaser of intracellular $Ca^{2+}$, 10\;{\mu}M$ for 4 min). Similarly, the preperfusion of hydrocortisone (30\;{\mu}M$) for 20 min also attenuated significantly the secretory responses of CA evoked by nicotinic and muscarinic receptor stimulation as well as membrane-depolarization, $Ca^{2+}$ channel activation and the release of intracellular $Ca^{2+}$. Furthermore, even in the presence of betamethasone (30{\mu}M$), CA secretion evoked by ACh, excess K^+$, DMPP and McN-A-343 was also markedly inhibited. Taken together, the present results suggest that glucocorticoids cause the marked inhibition of CA secretion evoked by both cholinergic nicotinic and muscarinic receptor stimulation from the isolated perfused rat adrenal gland, indicating strongly that this inhibitory effect may be mediated by inhibiting influx of extracellular calcium as well as the release of intracellular calcium in the rat adrenomedullary chromaffin cells.

• 대한약리학회지
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• 제30권1호
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• pp.87-100
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• 1994

도파민 함유세포가 교감신경절에 존재하는 것으로 알려져 있으나, 말초에서 신경전달 물질로써 그의 역할과 작용기전에 대해서 아직까지 알려진 바가 많지 않다. 따라서 본 연구에서는 도파민 $D_2$-수용체의 선택적인 효능약으로 알려진 apomorphine이 흰쥐 적출 관류 부신에서 카테콜아민(CA)분비작용에 미치는 영향을 연구코자 시도하여 다음과 같은 연구결과를 얻었다. $10{\um}M\;Apomorphine$의 비교적 낮은 농도를 부신정맥내에 20분간 관류 하였을때 5.32mM ACh, 56mM KCl, $100{\mu}M$ DMPP 및 $100{\mu}M$ McN-A-343 등의 투여에 의한 CA 분비작용이 의의 있게 감소되었다. Apomorphine 농도를 $30{\mu}M$로 증가시켜 관류하였을때 상기약물에 의한 CA 분비작용은 더욱 억제되었으며 또한 Bay-K-8644에 의한 $100{\mu}M$의 고농도로 전처치 하였을때, ACh, excess $K^+$, DMPP 및 McN-A-343에 의한 CA분비작용은 현저히 차단되었다. 도파민 $D_2$-수용체 차단제인 metoclopramide $(30{\mu}M)$으로 20분간 관류 하였을때 ACh, DMPP 및 McN-A-343에 의한 CA 분비작용은 유의하게 억제된 효과를 나타내었으나 $excess\;{K^+}$에 의한 CA분비작용은 별다른 영향을 받지 않았다. 그러나 metoclopramide $(30{\mu}M)$ 존재하에서 $30{\mu}M$ apomorphine으로 20분간 전처치 하였을때 $excess{K^+}$ 뿐만 아니라 DMPP의 CA 분비작용은 별다른 변화를 받지 않았다. 이상과 같은 실험 연구결과를 종합하여 보면, apomorphine은 cholinergic receptor stimulation과 membrane depolarization에 의한 CA 분비작용을 용량의존적으로 억제하여, 이러한 작용은 억제성 도파민 수용체를 활성화 시킴으로써 흰쥐 부신 수질의 chromaffin cell 내로 칼슘의 유입을 억제하여 나타나는 것으로 사료된다.