• Title/Summary/Keyword: inhibition effect

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Effect of Seed Mixture on Forage Yields and Botanical Composition at an Altitude of 400 m in Jeju island (표고 400m 제주 중산간 지역에서 혼합조합별 초지 생산성 및 식생구성)

  • Chae, Hyun Seok;Kim, Nam Young;Woo, Jae Hoon;Shin, Moon Cheol;Son, Jun Kyu;Seong, Pil Nam;Lee, Wang Shik;Kim, Si Hyun;Hwang, Kyung Jun;Kim, Young Jin;Park, Nam Gun
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.37 no.1
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    • pp.19-27
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    • 2017
  • The objective of this study was to determine the growth characteristics of cool (C1) and warm season grasses (C2) in pastures mixed with C1 and C2 at an altitude of 400 m in Jeju island to establishing pasture suitable for grazing horses and to evaluate the effect of pastures mixed with tall and short type grasses on the intake characteristics of horses. C1 used in this study was Kentucky bluegrass, redtop (short type grass) and tall type grasses were orchardgrass and tall fescue, respectively. Treatments of this study were consisted of four groups and the short type grass used in pastures mixed with C1 and C2 was mainly bermudagrass. Four treatment groups were follow as; Treatment 1 (bermudagrass + Kentucky bluegrass + redtop) 2) Treatment 2 (bermudagrass + tall fescue + orchardgrass) 3) Treatment 3 (Kentucky bluegrass + redtop) 4) Treatment 4 (tall fescue + orchardgrass). Bermudagrass was a little winter killing and inhibition of plant growth at an altitude of 400 m. Plant heights in pastures mixed with C1 and C2 were grown better than that in pastures mixed with C1. Especially, plant height in Treatment 4 was higher than other treatments. Dry matter yield was in the following order: Treatment 4> Treatment 3> Treatment 2> Treatment 1. Dry matter yield in pastures mixed with C1 increased as compared with pastures mixed with C1 and C2. Dry matter yield in Treatment 3 was higher than other treatments. In the first investigation regarding vegetation distribution, bermudagrass ratios among grasses in Treatment 1 and Treatment 2 were 11.7 and 13.3%, respectively. The growth of bermudagrass in winter was low due to the cold damage. However the growth of Kentucky bluegrass, redtop, tall fescue and orchardgrass was good. In the second investigation, bermudagrass ratios among grasses in Treatment 1 and Treatment 2 were 5.0 and 11.7%, respectively. Growth of forage in the second investigation was poor as compared to the first investigation. nutritive values(crude protein content, neutral detergent fiber content, acid detergent fiber content, digestibility) were good in pastures mixed with C1 Especially, nutritive values in pastures mixed with tall was higher than those of pastures mixed short grasses. P content among minerals in Treatment 1 was higher than other groups. However, the content of Ca, Mg and Mn were lower. The contents of Ca, K, Mg, Na, Cu, Zn and Fe in Treatment 2 were higher. However, the contents of K, Mg, Na, Cu, Zn and Fe in Treatment 3 were lower. Therefore, we suggest that cool season grasses with short grasses were sowed to establishing pasture suitable for grazing horses at an altitude of 400 m in Jeju island.

Role of PI3K/Akt Pathway in the Activation of IκB/NF-κB Pathway in Lung Epithelial Cells (폐 상피세포에서 PI3K/Akt 경로가 IκB/NF-κB 경로의 활성화에 미치는 영향)

  • Lee, Sang-Min;Kim, Yoon Kyung;Hwang, Yoon-Ha;Lee, Chang-Hoon;Lee, Hee-Seok;Lee, Choon-Taek;Kim, Young Whan;Han, Sung Koo;Shim, Young-Soo;Yoo, Chul-Gyu
    • Tuberculosis and Respiratory Diseases
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    • v.54 no.5
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    • pp.551-562
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    • 2003
  • Background : NF-${\kappa}B$ is a characteristic transcriptional factor which has been shown to regulate production of acute inflammatory mediators and to be involved in the pathogenesis of many inflammatory lung diseases. There has been some evidence that PI3K/Akt pathway could activate NF-${\kappa}B$ in human cell lines. However, the effect of PI3K/Akt pathway on the activation of NF-${\kappa}B$ varied depending on the cell lines used in the experiments. In this study we evaluated the effect of PI3K/Akt pathway on the activation of NF-${\kappa}B$ in human respiratory epithelial cell lines. Methods : BEAS-2B, A549 and NCI-H157 cell lines were used in this experiment. To evaluate the activation of Akt activation and I${\kappa}B$ degradation, cells were analysed by western blot assay using phospho-specific Akt Ab and $I{\kappa}B$ Ab. To block PI3K/Akt pathway, cells were pretreated with wortmannin or LY294002 and transfected with dominant negative Akt (DN-Akt). For IKK activity, immune complex kinase assay was performed. To evaluate the DNA binding affinity and transcriptional activity of NF-${\kappa}B$, electrophoretic mobility shift assay (EMSA) and luciferase assay were performed, respectively. Results : In BEAS-2B, A549 and NCI-H157 cell lines, Akt was activated by TNF-$\alpha$ and insulin. Activation of Akt by insulin did not induce $I{\kappa}B{\alpha}$ degradation. Blocking of PI3K/Akt pathway via wortmannin/LY294002 or DN-Akt did not inhibit TNF-$\alpha$-induced $I{\kappa}B{\alpha}$ degradation or IKK activation. Inhibition of PI3K/Akt did not affect TNF-$\alpha$-induced NF-${\kappa}B$ activation. Overexpression of DN-Akt did not block TNF-$\alpha$-induced transcriptional activation of NF-${\kappa}B$, but wortmannin enhanced TNF-$\alpha$-induced in NF-${\kappa}B$ transcriptional activity. Conclusion : PI3K/Akt was not involved in TNF-$\alpha$-induced $I{\kappa}B{\alpha}$ degradation or transcriptional activity of NF-${\kappa}B$ in human respiratory epithelial cell lines.

Changes of Refractive Correction Value with Different Age Group: A Case for Myopia Control Lens, Single Vision Lens and Reverse Geometry Contact Lens (Myopia Control Lens, Single Vision Lens, Reverse Geometry Contact Lens의 연령에 따른 굴절교정상태 변화에 대한 추적 연구)

  • Yoon, Min-Hwa
    • Journal of Korean Ophthalmic Optics Society
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    • v.18 no.1
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    • pp.75-84
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    • 2013
  • Purpose: Changes of refractive correction value in different age group were investigated. Regarding the inhibitive effects against myopia progression after wearing reverse geometry contact lenses and myopia control lenses (MC lenses), the effects after wearing single vision lenses were compared. Methods: We organized children between the ages of six and fifteen into three groups by age, and distributed fifty-seven reverse geometry contact lenses, fifty-six MC lenses and seventy-eight single vision lenses among them to be worn. Group 1 consisted of children aged ten and under, Group 2 consisted of children between the ages of eleven and fifteen, and Group 3 represents all of the study participants. The aim of this study was to learn the inhibitive effects against myopia progression attained by changes of refractive correction value and to verify their statistical significance at twelve months and under, thirteen to twenty-four months and twenty-five to thirty-six months. Results: Changes of refractive correction value by each length of use in Group 3 were as follows. For the age group of under twelve months, participants using the reverse geometric contact lens showed no change, while those using the MC or single vision lens had significant changes (P<0.05) of $-0.36{\pm}0.10$ D and $-0.67{\pm}0.52$ D, respectively. Users of all three lens types displayed significant change (P<0.05), in the age group of between thirteen and twenty-four months, of $0.18{\pm}0.49$ D, $0.60{\pm}0.42$ D and $1.37{\pm}0.72$ D for users of the reverse geometry contact lens, the MC lens and the single vision lens, respectively. There were significant changes (P<0.05) of $0.29{\pm}0.61$ D, $0.93{\pm}0.57$ D and $1.72{\pm}0.78$ in the same respective order as the above in the age group of twenty-five to thirty-six months. Refractive correction value showed changes with different age group. Group 1 displayed significant changes (P<0.05) of $0.29{\pm}0.73$ D, $1.07{\pm}0.59$ D and $1.75{\pm}0.74$ D for users of the reverse geometry contact lens, MC lens and single vision lens, respectively, up to thirty-six months of lens wearing; Group 2, also up to thirty-six months, displayed significant changes (P<0.05) of $0.28{\pm}0.42$ D, $0.75{\pm}0.49$ D and $1.70{\pm}0.84$ D in the same respective order, and changes in refractive correction for the age group under ten years was significantly greater (P<0.05) for the age group of eleven and older. Conclusions: The results found in this study demonstrate that there were no changes of refractive correction value for the case of wearing reversing geometry contact lens up to twelve month or less. MC lens showed less changes in variations of visual acuity for all users which might be resulted in inhibiting progression of myoptia. When both reverse geometry contact lens and the MC lens are wearing for the period from 13 to 36 month, both lens showed less changes in variation of visual acuity for all users. The results suggested that the less changes in variation of visual acuity of both lens had an effect on inhibiting progression of myopia.

Antagonistic Interaction between Quinclorac and Bensulfuron-methyl on Growth of the Rice Plants (Quinclorac과 Bensulfuron-methyl의 혼합처리(混合處理)에서 벼의 생장(生長)에 대한 제초제간(除草劑間) 길항작용(拮抗作用))

  • Kwon, Oh-Yeon;Kwon, Yong-Woong
    • Korean Journal of Weed Science
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    • v.17 no.3
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    • pp.288-294
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    • 1997
  • Field and pot expeiments were carried out to evaluate the interaction between quinclorac and bensulfuron-methyl on growth of the rice plants(Oryza sativa L. cv. Choocheongbyeo) at 20, 45, 65 days-old stages. Quinclorac and bensulfuron-methyl showed antagonistic interaction at both stages, which were detected by the Chisaka's method at isobles of 10% growth inhibition. The antagonism indices were -0.63 and -1.67 at 20 and 65 days-old seedling stages, respectively. Leaf-rolling of rice occurred when quinclorac was applied at 600g ai/ha or more at 20 days-old seedling stage, while it occured at the dose of 900g ai/ha at 65 days-old stage. Bensulfuron-methyl reduced plant height and dry weight as well as tiller production at both stages. Leaf-rolling of rice was reduced when mixture of quinclorac and bensulfuron-methyl was applied due to antagonism of the two herbicides. High temperatures increased the phytotoxicity of bensulfuron-methyl, while the phytotoxicity caused by quinclorac alone was not responsive to temperature. The antagonistic effect between quinclorac and bensulfuron-methyl increased at low temperature as tested by the Colby's method.

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Effect of $H_2O_2$ on Alveolar Epithelial Barrier Properties (폐상피세포 장벽에 대한 $H_2O_2$의 영향)

  • Suh, Duk-Joon;Cho, Se-Heon;Kang, Chang-Woon
    • Tuberculosis and Respiratory Diseases
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    • v.40 no.3
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    • pp.236-249
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    • 1993
  • Background: Among the injurious agents to which the lung airspaces are constantly exposed are reactive species of oxygen. It has been widely believed that reactive oxygen species may be implicated in the etiology of lung injuries. In order to elucidated how this oxidant causes lung cell injury, we investigated the effects of exogenous $H_2O_2$ on alveolar epithelial barrier characteristics. Methods: Rat type II alveolar epithelial cells were plated onto tissue culture-treated polycarbonate membrane filters. The resulting confluent monolayers on days 3 and 4 were mounted in a modified Ussing chamber and bathed on both sides with HEPES-buffered Ringer solution. The changes in short-circuit current (Isc) and monolayer resistance (R) in response to the exogenous hydroperoxide were measured. To determine the degree of cellular catalase participation in protection against $H_2O_2$ injury to the barrier, experiments were repeated in the presence of 20 mM aminotriazole (ATAZ, an inhibitor of catalase) in the same bathing fluid as the hydroperoxide. Results: These monolayers have a high transepithelial resistance (>2000 ohm-$cm^2$) and actively transport $Na^+$ from apical fluid. $H_2O_2$(0-100 mM) was then delivered to either apical or basolateral fluid. Resulting indicated that $H_2O_2$ decreased Isc and R gradually in dose-dependent manner. The effective concentration of apical $H_2O_2$ at which Isc (or R) was decreased by 50% at one hour ($ED_{50}$) was about 4 mM. However, basolateral $H_2O_2$ exposure led to $ED_{50}$ for Isc (and R) of about 0.04 mM. Inhibition of cellular catalase yielded $ED_{50}$ for Isc (and R) of about 0.4 mM when $H_2O_2$ was given apically, while $ED_{50}$ for basolateral exposure to $H_2O_2$ did not change in the presence of ATAZ. The rate of $H_2O_2$ consumption in apical and basolateral bathing fluids was the same, while cellualr catalase activity rose gradually with time in culture. Conclusion: Our data suggest that basolateral $H_2O_2$ may affect directly membrane component (e.g., $Na^+,\;K^+$-ATPase) located on the basolateral cell surface. Apical $H_2O_2$, on the other hand, may be largely degraded by catalase as it passes through the cells before reaching these membrane components. We conclude that alveolar epithelial barrier integrity as measured by Isc and R are compromised by $H_2O_2$ being relatively sensitive to basolateral (and insensitive to apical) $H_2O_2$.

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Depression of Immune Response by Newcastle Disease Virus Infection (Newcastle병(病) 바이러스감염(感染)에 의(依)한 면역반응억제(免疫反應抑制))

  • Kim, Hwan-Jong;Ha, Tai-You
    • The Journal of the Korean Society for Microbiology
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    • v.14 no.1
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    • pp.79-87
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    • 1979
  • The immunosuppressive activity of newcastle disease virus(NDV) and some possible role of interferon(C-IF) in viral suppression of immune response were evaluated by SRBC-induced delayed-type hypersensitivity(DTH), rosette formation in spleen cells, number of lymphocytes in peripheral blood, hemagglutinin and hemolysin response to SRBC in ICR mice sensitized with SRBC. When NDV was inoculated before or after sensitization of mouse with SRBC, virus caused a marked inhibition of DTH, and its depressive effect was dependent on the time of virus inoculation in relation to SRBC sensitization or challenge. Rosette formation of spleen cells was significantly reduced by NDV infection. The degree of the depression of rosette formation was more prominent in mice inoculated before sensitization than after sensitization and could be related to the amount of serum interferon induced by the virus. Humoral response to SRBC of virus infected mouse was significantly depressed when NDV was inoculated 24 or 48 hours before sensitization. However, there was no difference in the response when the virus was inoculated 9 hour before and at the same time of sensitization or even after that. Lymphocytes in peripheral blood of mice were markedly diminished in numbers when NDV was inoculated 48 and 24 hour before sensitization with SRBC, but they were slightly augmented when the virus was inoculated 9 hour before and at the same time of sensitization. When UV-inactivated or heat-inactivated NDV was injected to the mouse at the same time of sensitization with SRBC, DTH and rosette formation of spleen cells were slightly depressed. DTH and rosette formation in mice treated with crude-IF were generally depressed as com pared with those of control mice. These studies suggest that the NDV causes a significant depression of cell-mediated immunity, whereas the humoral immune response is not inhibited markedly, and that the depression of immune response by NDV infection may be caused by interferon produced by NDV and direct viral activity.

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The Study of anti-cancer mechanism with Cobrotoxin on Human prostatic cancer cell line(PC-3) (전립선 암세포에 대한 Cobrotoxin의 항암(抗癌) 기전(機轉) 연구(硏究))

  • Chae, Sang-jin;Song, Ho-seup
    • Journal of Acupuncture Research
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    • v.22 no.3
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    • pp.169-183
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    • 2005
  • Objective : The purpose of this study was to investigate the anti-caner effect of cobrotoxin on the prostatic cancer cell line (PC-3).The goal of study is to ascertain whether cobrotoxin inhibits tile cell growth and cell cycle of PC-3, or the expression of relative genes and whether the regression of PC-3 cell growth is due to cell death or the expression of gene related to apoptosis. Methods : After the treatment of Pc-3 cells with cobrotoxin, we performed 형광현미경, MTT assay, Western blotting, Flow cytometry, PAGE electrophoresis and Surface plasmon resonance analysis to identify the cell viability, cell death, apoptosis, the changes of cell cycle and the related protein, Adk, MAP kinase. Results : 1. Compared with normal cell, the inhibition of cell growth reduced in proportion with the dose of cobrotoxin(0-16nM) in PC-3. 2. Cell viabilities of 0.1, 1, 4nM cobrotoxin treatment were decreased and those of 8, 16nM were decreased significantly. 3. S phase of cell cycle was decreased at the group of 1, 2, 4, 8, 16nM cobrotoxin, but M phase was increased at 0.1, 1, 2, 4, 8, 16nM cobrotoxin. 4. Cox-2 expression after cobrotoxin was peaked at 12hours and was decreased significantly after 6, 12, 24 hours. 5. The expression of Cdk4 was decreased dose-dependently at 1, 2, 4, 8nM cobrotoxin and was decreased siginificantly at 4, 8nM Cyclin D1 was decreased at 1, 2, 4, 8nM and Cycline E was not changed. Cycline B was decreased at 1, 2, 4, 8nM dose-dependently and was decreased siginificanlty at 2, 4, 8nM. 6. The expression of Akt was decreased at 1, 2, 4, 8nM dose-dependently and was decreased significantly at 2, 4, 8nM. 7. ERK was increased at 1, 2nM and decreased at 4, 8nM, p-ERK was increased at 1, 2, 4 nM, but decreased at 8nM. JNK and p-JNK were increased at 1, 4, 8 nM. p38 was increased at 2nM p-p38 was increased at lnM but decreased significantly at 2, 4, 8nM. 8. The nucli of normal cells were stained round and homogenous in DAPI staining, but those of PC-3 were stained condense and splitted. Apoptosis was increased dose-dependently at 2, 4, 8, 16nM and increased significantly at 2, 4, 8, 16nM. 9. Bax wasn`t changed at 1, 2, 4, 8nM and Bcl-2 was decreased significantly at 1, 2, 4, 8nM. Caspase 3 and 9 weren`t changed at 1, 2, 4nM but were decreased significantly at 8nM. Conclusions : These results indicate that cobrotoxin inhibits the growth of prostate Cancer cells, has anti-cancer effects by inducing apoptosis.

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A Study of Endothelium-dependent Pulmonary Arterial Relaxation and the Role of Nitric oxide on Acute Hypoxic Pulmonary Vasoconstriction in Rats (흰쥐 폐동맥의 내피세포의존성 혈관이완과 급성 저산소성 폐동맥수축에서 산화질소의 역할)

  • In, Kwang-Ho;Lee, Jin-Goo;Cho, Jae-Youn;Shim, Jae-Jung;Kang, Kyung-Ho;Yoo, Se-Hwa
    • Tuberculosis and Respiratory Diseases
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    • v.41 no.3
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    • pp.231-238
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    • 1994
  • Backgroud: Since the demonstration of the fact that vascular relaxation by acetylcholine(Ach) results from the release of relaxing factor from the endothelium, the identity and physiology of this endothelium-derived relaxing factor(EDRF) has been the target for many researches. EDRF has been identified as nitric oxide(NO). With the recent evidences that EDRF is an important mediator of vascular tone, there have been increasing interests in defining the role of the EDRF as a potential mediator of hypoxic pulmonary vasoconstriction. But the role of EDRF in modulating the pulmonary circulation is not compeletely clarified. To investigate the endothelium-dependent pulmonary vasodilation and the role of EDRF during hypoxic pulmonary vasoconstriction, we studied the effects of $N^G$-monomethyl-L-arginine(L-NMMA) and L-arginine on the precontracted pulmonary arterial rings of the rat in normoxia and hypoxia. Mothods: The pulmonary arteries of male Sprague Dawley(300~350g) were dissected free of surrounding tissue, and cut into rings. Rings were mounted over fine rigid wires, in organ chambers filled with 20ml of Krebs solution bubbled with 95 percent oxygen and 5 percent carbon dioxide and maintained at $37^{\circ}C$. Changes in isometric tension were recorded with a force transducer(FT.03 Grass, Quincy, USA) Results: 1) Precontraction of rat pulmonry artery with intact endothelium by phenylephrine(PE, $10^{-6}M$) was relaxed completely by acetylcholine(Ach, $10^{-9}-10^{-5}M$) and sodium nitroprusside(SN, $10^{-9}-10^{-5}M$), but relaxing response by Ach in rat pulmonary artery with denuded endothelium was significantly decreased. 2) L-NMMA($10^{-4}M$) pretreatment inhibited Ach($10^{-9}-10^{-5}M$)-induced relaxation, but L-NMMA ($10^{-4}M$) had no effect on relaxation induced by SN($10^{-9}-10^{-5}M$). 3) Pretreatment of the L-arginine($10^{-4}M$) significantly reversed the inhibition of the Ach ($10^{-9}-10^{-5}M$)-induced relaxation caused by L-NMMA($10^{-4}M$) 4) Pulmonary arterial contraction by PE($10^{-6}M$) was stronger in hypoxia than normoxia but relaxing response by Ach($10^{-9}-10^{-5}M$) was decreased, 5) With pretreatment of L-arginine($10^{-4}M$), pulmonary arterial relaxation by Ach($10^{-9}-10^{-5}M$) in hypoxia was reversed to the level of relaxation in normoxia. Conclusion: It is concluded that rat pulmonary arterial relaxation by Ach is dependent on the intact endothelium and is largely mediated by NO. Acute hypoxic pulmonary vasoconstriction is related to the suppression on NO formation in the vascular endothelium.

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Diagnosis of the Field-Grown Rice Plant -[1] Diagnostic Criteria by Flag Leaf Analysis- (포장재배(圃場栽培) 수도(水稻)의 영양진단(營養診斷) -1. 지엽분석(止葉分析)에 의(依)한 진단(診斷)-)

  • Park, Hoon
    • Applied Biological Chemistry
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    • v.16 no.1
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    • pp.18-30
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    • 1973
  • The flag and lower leaves (4th or 5th) of rice plant from the field of NPK simple trial and from three low productive area were analyzed in order to find out certain diagnostic criteria of nutritional status at harvest. 1. Nutrient contents in the leaves from no fertilizer, minus nutrient and fertilizer plots revealed each criterion for induced deficiency (severe deficient case induced by other nutrients), deficiency (below the critical concentration), insufficiency (hidden hunger region), sufficiency (luxuary consumption stage) and excess (harmful or toxic level). 2. Nitrogen contents for the above five status was less than 1.0%, 1.0 to 1.2, 1.2 to 1.6, 1.6 to 1.9 and greater than 1.9, respectively. 3. It was less than 0.3%, 0.3 to 0.4, 0.4 to 0.55 and greater than 0.55 for phosphorus $(P_2O_5)$ but excess level was not clear. 4. It was below 0.5%, 0.5 to 0.9, 0.9 to 1.2, 1.2 to 1.4 and above 1.4 for potassium. 5. It was below 4%, 4 to 6, 6 to 11 and above 11 for silicate $(SiO_2)$ and no excess was appeared. 6. Potassium in flag leaf seemed to crow out nitrogen to ear resulting better growth of ear by the inhibition of overgrowth of flag leaf. 7. Phosphorus accelerated the transport of Mg, Si, Mn and K in this order from lower leaf to flag, and retarded that of Ca and N in this order at flowering while potassium accelerated in the order of Mn, and Ca, and retarded in the order of Mg, Si, P and N at milky stage. 8. Transport acceleration index (TAI) expressed as (F_2L_1-F_1L_2)\;100/F_1L_1$ where F and L stand for other nutrient cotents in flag and lower leaf and subscripts indicate the rate of a nutrient applied, appears to be suitable for the effect of the nutrient on the translocation of others. 9. The content of silicate $(SiO_2)$ in the flag was lower than that of lower leaf in the early season cultivation indicating hinderance in translocation or absorption. It was reverse in the normal season cultivation. 10. The infection rate of Helminthosporium frequently occurred in the potassium deficient field seemed to be related more to silicate and nitrogen content than potassium in the flag leaf. 11. Deficiency of a nutrient occured simultaniously with deficiency of a few other ones. 12. Nutritional disorder under the field condition seems mainly to be attributed to macronutrients and the role of micronutrient appears to be none or secondary.

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Effects of insulin and IGF on growth and functional differentiation in primary cultured rabbit kidney proximal tubule cells - Effects of IGF-I on Na+ uptake - (초대배양된 토끼 신장 근위세뇨관세포의 성장과 기능분화에 대한 insulin과 IGF의 효과 - Na+ uptake에 대한 IGF-I의 효과 -)

  • Han, Ho-jae;Park, Kwon-moo;Lee, Jang-hern;Yang, IL-suk
    • Korean Journal of Veterinary Research
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    • v.36 no.4
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    • pp.783-794
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    • 1996
  • It has been suggested that ion transport systems are intimately involved in mediating the effects of growth regulatory factors on the growth of a number of different types of animal cells in vivo. The functional importance of the apical membrane $Na^+/H^+$ antiporter in the renal proximal tubule is evidenced by estimates that this transporter mediates the reabsorption of approximately one third of the filtered load of sodium and the bulk of the secretion of hydrogen ions. This study was designed to investigate the pathway utilized by IGF-I in regulating sodium transport in primary cultured renal proximal tubule cells. Results were as follows : 1. $Na^+$ was observed to accumulate in the primary cells as a function of time. Raising the concentration of extracellular NaCl induced an decrease in $Na^+$ uptake compared with control cells in a dose dependent manner. The rate of $Na^+$ uptake into the primary cells was about two times higher in the absence of NaCl($40.11{\pm}1.76pmole\;Na^+/mg\;protein/min$) than in the presence of 140mM NaCl($17.82{\pm}0.94pmole\;Na^+/mg\;protein/min$) at the 30 minute uptake. 2. $Na^+$ uptake was inhibited by IAA($1{\times}10^{-4}M$) or valinomycin($5{\times}10^{-6}M$) treatment($50.51{\pm}4.04$ and $57.65{\pm}2.27$ of that of control, respectively). $Na^+$ uptake by the primary proximal tubule cells was significantly increased by ouabain($5{\times}10^{-5}M$) treatment($140.23{\pm}3.37%$ of that of control). When actinomycin D($1{\times}10^{-7}M$) or cycloheximide($4{\times}10^{-5}M$) was applied, $Na^+$ uptake was decreased to $90.21{\pm}2.39%$ or $89.64{\pm}3.69%$ of control in IGF-I($1{\times}10^{-5}M$) treated cells, respectively. 3. Extracellular cAMP decreased $Na^+$ uptake in a dose-dependent manner($10^{-8}-10^{-4}M$). IBMX($5{\times}10^{-5}M$) also inhibited $Na^+$ uptake. Treatment of cells with pertussis toxin(50pg/ml) or cholera toxin($1{\mu}g/ml$) inhibited $Na^+$ uptake. Extracellular PMA decreased $Na^+$ uptake in a dose-dependent manner(1-100ng/ml). 100 ng/ml PMA concentration significantly inhibited $Na^+$ uptake in IGF-I treated cells. However, staurosporine($1{\times}10^{-7}M$) had no effect on $Na^+$ uptake. When PMA and staurosporine were added together, the inhibition of $Na^+$ uptake was not observed. In conclusion, sodium uptake in primary cultured rabbit renal proximal tubule cells was dependent on membrane potentials and intracellular energy levels. IGF-I stimulates sodium uptake through mechanisms that involve some degree of de novo protein and/or RNA synthesis, and cAMP and/or PKC pathway mediating the action mechanisms of IGF-I.

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