• 한국세라믹학회지
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• 제28권5호
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• pp.373-382
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• 1991

The effect of Ca/P mole ratio (Ca/P=1.60, 1.67, 1.75) in the initial solution on the mechanical properties of alumina added hydroxyapatite was investigated. Hydroxyapatite was synthesized by precipitation method using Ca(NO3)2$.$4H2O and (NH4)2HPO4 as starting materials and 5 wt% of ${\alpha}$-Al2O3 was added to precipitation solution. The powder was calcined at 800$^{\circ}C$ and sintered at 1,150∼1,400$^{\circ}C$ under water vapor atmosphere. With the increasing of Ca/P mole ration in the initial solution, the amount of tricalcium phosphate formed from the decomposition of hydroxyapatite reduced and the sinterability and mechanical properties were increased. The bending strength and Vickers hardness of the specimen sintered at 1,300$^{\circ}C$ with the Ca/P mole ratio of 1.75 in the initial solution were 230 MPa and 650 kg/$\textrm{mm}^2$, respectively. The improvement of mechanical properties was attributed to not only the effect of Ca/P mole ratio but also the strengthening of sintered body by Al substitution for P ions.

• 한국결정성장학회지
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• 제8권3호
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• pp.503-507
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• 1998

마이크로파 유전체로 응용되는 $xCaTiO_3-La(Zn_{1/2}Ti_{1/2})O_3$계의 소결시 고용조성 변화(x=0.4-0.6) 및 소결거동에 따른 유전특성에 조사하였다. 소결밀도가 감소함에 따라 유전상수는 감소하였으며 품질계수(Q)는 증가하다 일정한 값을 유지하였다. 고용체형의 경우 유전상수는 $CaTiO_3$조성 증가에 따라 증가하였다. $0.5\;CaTIO_3\;0.5\;La(Zn_{1/2}Ti_{1/2})O_3$의 경우 유전상수 48, 온도계수는 $-1ppm/^{\circ}C$를 나타내었다.

• 대한화학회지
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• 제52권2호
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• pp.164-168
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• 2008

마이크로 에멀젼 방법으로 CaWO4 결정을 합성하였다. CTAB에 대한 H2O의 몰랄 농도비(w)를 변 화시켜서 다양한 크기와 형태의 CaWO4를 얻었다. w=5와 w=10일 때 각각 100 nm와 500 nm 길이의 타원형 CaWO4 결정을 얻었다. w=20일 때는 1 μm의 막대형 CaWO4 결정을 얻었다. w=30에서는 길이가 약 2~3 μm인 구형의 CaWO4 결정을 얻었다. CTAB에 대한 H2O의 몰랄 농도비가 증가 할수록 응집에 의해서 CaWO4 결정 의 모양은 타원형에서 막대형태를 거쳐서 구형으로 변했다.

• 한국가금학회지
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• 제22권4호
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• pp.193-202
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• 1995

This study was carried out to investigate the effects of diverse dietary Ca levels and to determine whether bone mineral metabolism is influenced by the arnount of dietary Ca when given a choice of diets containing various levels of Ca. Forty Hy-line brown laying hens housed in separate cages were fed self-selected Ca diets. Birds were allowed a 7-day adaptation period followed by an 8-day collection period. Feed and water were available for ad libitum consumption. Eggs and excreta were collected at 6-h intervals during the day for mineral analysis. The Ca contents in excreta and retained Ca in the body on egg forming day were proportional to the amount of daily Ca intake. The retained Ca in the body were 0.97 g in control and 1.24~1.74 g in self-selected groups, respectively. Daily Ca contents (%) in tibial cortex were not consistent with feeding time intervals. The Ca content in tibial medulla in control group was lower than those of self-selected feeding groups(P<.05). The medullary Ca content in all treatment groups increased from 10:00 to 16:00 in a day. Ca content in plasma was low between 10:00 and 16:00 and was high between 22:00 and 04:00 in the following day.

• Archives of Pharmacal Research
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• 제10권2호
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• pp.80-87
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• 1987

To get a better insight into the exxistence and the role of a Na-Ca exchange mechanism in smooth muscle, the effect of Na substitution with sucrose on tension development, cellular Ca uptake and $^{45}Ca$ efflux was investigated using isolated cat ileal longitudinal muscle strips. Experimental results were summarized as follows;1) Exposure of the cat ileal longitudinal muscle to Na-free solution induced a contraction, and the magnitude of the contraction increased after incubation of the muscle strips with ouabain ($2{\times10^{-}5}$M) for 1hr. 2) Cellular Ca uptake in Na-free solution increased with an increase in Na content of the Na-loading media, and a linear relationship existed between tissue Na content and cellular Ca uptake for 10 min 3) After tissues were equilibrated in PSS containing $^{45}Ca$ for 2hr, cellular Ca uptake decreased with rising the external Na concentration. 4)Removal of medium Na or inhibition of the Na-K pump decreased the rate of $^{45}Ca$ efflux. These results strongly suggested that Na substitution increases cellular Ca uptake and decreases the rate of $^{45}Ca$ efflux via a Na-Ca exchange mechanism.

• 한국자기공명학회논문지
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• 제19권2호
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• pp.74-82
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• 2015

Ryanodine receptor (RyR) is one of the two major $Ca^{2+}$ channels in membranes of intracellular $Ca^{2+}$ stores and is found in sarcoplasmic reticulum (SR), endoplasmic reticulum (ER). RyR1 is also the major calmodulin-binding protein of sarcoplasmic reticulum membranes. Residues 4064-4210 in the RyR1 polypeptide chain has similar primary sequence with calmodulin (CaM) and was designated as CaM-like domain (CaMLD). When expressed as a recombinant peptide, CaMLD showed several CaM-like properties in previous studies. Still, previous studies of CaMLD were focused on protein-protein interactions rather than its own properties. Here, we studied the expression of CaMLD and its sub-domains corresponding to each lobe of CaM in Escherichia coli. CaMLD could be obtained only as inclusion body, and it was refolded using urea solubilization followed by dialysis. Using spectroscopic approaches, such as NMR, circular dichroism, and gel filtration experiment, we found that the refolded CaMLD exists as nonspecific aggregate, even though it has alpha helical secondary structure. In comparison, the first half of CaMLD (R4061-4141) could be obtained as natively soluble protein with thioredoxin fusion. After the removal of the fusion tag, it exhibited folded and helical properties as shown by NMR and circular dichroism experiments. Its oligomeric status was different from CaMLD, existing as dimeric form in solution. However, the second half of the protein could not be obtained as soluble protein regardless of fusion tag. Based on these results, we believe that CaMLD, although similar to CaM in sequence, has quite different physicochemical properties and that the second half of the protein renders it the aggregative properties.

• 식물조직배양학회지
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• 제21권6호
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• pp.363-367
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• 1994

식물 세포의 신호전달 기작에 있어 calmodulin (CaM)의 역할을 조사하기 위하여 외부기원의 CaM을 식물 세포 내로 주입하였다. 이를 위하여 bovine testis로부터 CaM을 분리, 정제하여 SDS-PAGE상에서 순수함을 확인하였고, 이를 세포 내로 주입한 후 실제 주입 여부를 확인하기 위해 정제된 CaM을 미리 fluorescein isothiocyanate (FITC)로 표식하여 사용하였다. 또한, FITC-CaM complex의 농도에 따른 fluorescent intensity를 측정하여 주입된 CaM의 농도를 결정하였다. 대두 현탁 배양 세포를 saponin (0.1 mg/mL)이 포함된 배지에서 15분간 배양하여 permeabilization시키고,FITC-CaM (1mg/mL)을 30분간 처리한 후 형광현미경으로 조사했을 때 세포질에서 강한 형광이 나타났으며, 이 결과로 외부의 calmodulin이 세포 내로 주입되었음을 확인할 수 있었다. 대두 현탁 배양 세포에 3가지의 세포벽 분해 효소를 처리하여 원형질체를 분리하였고, 이 원형질체를 FITC-CaM이 들어있는 완충용액에 넣고 electroporation 하였을때 capacitance와 field strength가 증가할수록 원형질체의 생존률은 감소하였으나, 세포 내의 fluorescent intensity는 증가하였다. 이것은 외부의 calmodulin이 electroporation에 의해 대두의 원형질체 내로 도입되었음을 의미하는 것이다.

• The Korean Journal of Physiology and Pharmacology
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• 제10권1호
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• pp.25-30
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• 2006

Lysophosphatidylcholine (LPC), which accumulates in atherosclerotic arteries, has been reported to inhibit endothelium-dependent relaxation (EDR) in many different species. However, the underlying mechanism of LPC-induced inhibition of EDR is still uncertain. In the present study, we measured simultaneously both isometric tension and cytosolic free $Ca^{2+}$ ($[Ca^{2+}]_i$) in rabbit carotid strips, and examined the effect of LPC on tension and $[Ca^{2+}]_i$. In carotid strips with intact-endothelium, high $K^+$ (70 mM) increased both tension and $[Ca^{2+}]_i$, and cumulative addition of acetylcholine (ACh) from 0.1 to $10{\mu}M$ induced dose dependent increase of $[Ca^{2+}]_i$ with concomitant relaxation. In the presence of L-NAME (0.1 mM), ACh increased $[Ca^{2+}]_i$ without affecting the amplitude of high $K^+-induced$ tension. These ACh-induced change of $[Ca^{2+}]_i$ and tension was abolished by removal of endothelium or 10 nM 4-DAMP (muscarinic receptor antagonist) pretreatment. Pretreatment of LPC ($10{\mu}M$) inhibited ACh ($10{\mu}M$)-induced change of tension and $[Ca^{2+}]_i$ in endothelium-intact carotid artery. On the other hand, LPC had no effect on ACh-induced change of tension and $[Ca^{2+}]_i$ in endothelium denuded artery. In $Ca^{2+}$-free external solution, ACh transiently increased $[Ca^{2+}]_i$, and pretreatment of LPC significantly inhibited ACh-induced transient $[Ca^{2+}]_i$ change. Based on the above results, it may be concluded that LPC inhibits the ACh-induced $[Ca^{2+}]_i$ change through inhibition of $Ca^{2+}$ mobilization in vascular endothelial cells, resulting in decreased production of NO and concomitant inhibition of endotheliumdependent vascular relaxation.

• 한국동물학회지
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• 제17권1호
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• pp.5-16
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• 1974

초파리(Drosophila melanogaster)의 발생에 미치는 염화칼륨(KCI)과 염화칼슘($CaCl_2$)의 단독 영향 및 상호 작용을 검토하기 위하여 6가지 농도의 KCI이나 $CaCl_2$ 처리 메디아에 5계통의 초파리를 사육하여 우화율은 검토한 결과는 다음과 같다. 1. 우화율은 초파리 계통간에는 유의적인 차이를 볼 수 없으나, KCI이나 $CaCl_2$의 농도간에는 매우 유의적인 차이가 있으며, 그 농도가 커짐에 따라 우화율이 낮아진다. 2. 우화율에 미치는 $CaCl_2$의 억제적 효과는 KCI에 비하여 현저하게 크며, 이것은 초파리의 KCI에 대한 저항성이 $CaCl_2$에 대한 것 보다 크다는 것을 뜻한다. 3. KCI 이나 $CaCl_2$ 메디아에 소량의 $CaCl_2$ 이나 KCI를 첨가하면 KCI이나 $CaCl_2$ 의 우화율에 대한 억제적 효과의 길항작용을 보이고 있으나, 좀더 다량을 가하면 억제적 효과가 더욱 촉진된다. 4. 따라서 초파리의 발생에 대한 $K^+$ 와 $Ca^++$의 억제적 효과에 있어서 상호 작용이 관여하고 있음을 알수 있다.

• Toxicological Research
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• 제16권1호
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• pp.63-66
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• 2000

The effects of acute ethanol on the high K+ induced $Ca^{2+}}$ signals were examined from primary cultures of cerebellar granule neurons. $Ca^{2+}}$ signals were measured with Calcium Green-1 based microscopic video imaging. Because $Ca^{2+}}$ signal was low in most of granule neurons without stimuli, high KCI was used for depolarization. In most case, acute exposure to ethanol reduced the peak amplitude of the $Ca^{2+}}$ signals, induced by high K+, even though low concentration of ethanol(2~10mM) was used and the effects lasted more than 30min. In was also possible to see differences of ethanol inhibition, i.e. the temporal pattern of $Ca^{2+}}$ signal reductions and the strength of inhibition of $Ca^{2+}}$ signals in cerebellar granule neurons. These results indicate that low concentration of ethanol has diverse actions on the $Ca^{2+}}$ signals in cerebellar granule neurons.