• 대한수의학회지
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• 제38권1호
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• pp.29-42
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• 1998

$Mg^{2+}$ is one of the most abundant divalent cations in mammalian body(0.2~1.0mM) and the important physiological roles are : first, the cofactor of many enzyme activities, second, the regulator of glycolysis and DNA synthesis, third, the important role of bioenergetics by regulating of phosphorylation, fourth, the influence of cardiac metabolism and function. In this work we have investigated the regulation of the $Mg^{2+}$ induced by ${\alpha}_1-adrenoceptor$ stimulation in perfused guinea pig hearts and isolated myocytes. The $Mg^{2+}$ content of the perfusate or the supernatant was measured by atomic absorbance spectrophotometry. The elimination of $Mg^{2+}$ in the medium increased the force of contraction of right ventricular papillary muscles, and the left ventricular pressure. Phenylephrine also enhanced the force of contraction in the presence of $Mg^{2+}-free$ medium. ${\alpha}_1-Agonists$ such as phenylephrine and methoxamine were found to induce $Mg^{2+}$ efflux in both perfused hearts and myocytes. These effects were blocked by prazosin, an ${\alpha}_1-adrenoceptor$ antagonist. The $Mg^{2+}$ influx could also be induced by phenylephrine and R59022, a diacylglycerol kinase inhibitor. In the presence of protein kinase C(PKC) inhibitors, phenylephrine produced an increase in $Mg^{2+}$ efflux from perfused hearts. Furthermore, $Mg^{2+}$ efflux by phenylephrine was amplified by phorbol 12-myristate 13-acetate(PMA). This enhancement of $Mg^{2+}$ efflux by PMA was blocked by prazosin in perfused hearts. By contrast, the $Mg^{2+}$ influx could be induced by verapamil, nifedipine, ryanodine in perfused hearts, but not in myocytes. $W^7$, a $Ca^{2+}$/calmodulin antagonist, completely blocked the phenylephrine-induced $Mg^{2+}$ efflux in perfused hearts. In conclusion, $Mg^{2+}$ is responsible for the cardiac activity associated with ${\alpha}_1-adrenoceptor$ stimulation. The mobilization of $Mg^{2+}$ is decreased or increased by ${\alpha}_1-adrenoceptor$ stimulation in guinea pig hearts. These responses may be related specifically to the respective pathways of signal transduction. A decrease in $Mg^{2+}$ efflux by ${\alpha}_1-adrenoceptor$ stimulation in hearts can be through PKC dependent and intracellular $Ca^{2+}$ levels.

• Journal of Microbiology and Biotechnology
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• 제26권9호
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• pp.1605-1612
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• 2016

Quinolone-resistant Salmonella strains were isolated from patient samples, and several quinolone-sensitive strains were used to analyze mutations in the quinolone resistance-determining region (QRDR) of gyrA, gyrB, parC, and parE and to screen for plasmid-mediated quinolone resistance. Among the 21 strains that showed resistance to nalidixic acid and ciprofloxacin (MIC 0.125-2.0 μg/ml), 17 strains had a mutation in QRDR codon 87 of gyrA, and 3 strains had a single mutation (Ser83 → Phe). Another cause of resistance, efflux pump regulation, was studied by examining the expression of acrB, ramA, marA, and soxS. Five strains, including Sal-KH1 and Sal-KH2, showed no increase in relative expression in an analysis using the qRT-PCR method (p < 0.05). In order to determine the genes involved in the resistance, the Sal-9 isolate that showed decreased susceptibility and did not contain a mutation in the gyrA QRDR was used to make the STM (MIC 8 μg/ml) and STH (MIC 16 μg/ml) ciprofloxacin-resistant mutants. The gyrA QRDR Asp87 → Gly mutation was identified in both the STM and STH mutants by mutation analysis. qRT-PCR analysis of the efflux transporter acrB of the AcrAB-TolC efflux system showed increased expression levels in both the STM (1.79-fold) and STH (2.0-fold) mutants. In addition, the expression of the transcriptional regulator marA was increased in both the STM (6.35-fold) and STH (21.73-fold) mutants. Moreover, the expression of soxS was increased in the STM (3.41-fold) and STH (10.05-fold) mutants (p < 0.05). Therefore, these results indicate that AcrAB-TolC efflux pump activity and the target site mutation in gyrA are involved in quinolone resistance.

• Ocean Science Journal
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• 제40권2호
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• pp.79-89
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• 2005

Laboratory radiotracer experiments were conducted to determine assimilation efficiencies (AE) from ingested algal food and oxic sediment particles, uptake rates from the dissolved phase, and the efflux rates of Cd, Cr and Zn in the Asiatic clam Corbicula fluminea. Among three elements, AE from both algal and sediment food was greatest for Cd, followed by Zn and Cr. The AEs of tested elements from algal food (Phaeodactylum tricornutum) were consistently higher than those from sediments at a given salinity and temperature. The influence of salinity (0, 4 and 8 psu) and temperature (5, 13 and $21^{\circ}C$) on the metal AEs was not evident for most tested elements, except Cd AEs from sediment. The rate constant of metal uptake from the dissolved phase $(k_u)$ was greatest for Cd, followed by Zn and Cr in freshwater media. However, in saline water, the $(k_u)$ of Zn were greater than those of Cd. The influx rate of all tested metals increased with temperature. The efflux rate constant was greatest for Cr $(0.02\;d^{-1})$, followed by Zn $(0.010{\sim}0.017\;d^{-1})$ and $Cd\;(0.006\;d^{-1})$. The efflux rate constant for Zn in clam tissues depurated in 0 psu $(0.017\;d^{-1})$ was faster than that in 8 psu $(0.010\;d^{-1})$. Overall results showed that the variation of salinity and temperature in estuarine systems can considerably influence the metal bioaccumulation potential in the estuarine clam C. fluminea. The relatively high Cd accumulation capacity of C. fluminea characterized by the high AE, high dissolved influx rate and low efflux rate, suggested that this clam species can be used as an efficient biomonitor for the Cd contamination in freshwater and estuarine environments.

• Molecules and Cells
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• 제42권12호
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• pp.850-857
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• 2019

The Gram-negative opportunistic pathogen, Pseudomonas aeruginosa, has multiple multidrug efflux pumps. MexT, a LysR-type transcriptional regulator, functions as a transcriptional activator of the MexEF-OprN efflux system. MexT consists of an N-terminal DNA-binding domain and a C-terminal regulatory domain (RD). Little is known regarding MexT ligands and its mechanism of activation. We elucidated the crystal structure of the MexT RD at 2.0 Å resolution. The structure comprised two protomer chains in a dimeric arrangement. MexT possessed an arginine-rich region and a hydrophobic patch lined by a variable loop, both of which are putative ligand-binding sites. The three-dimensional structure of MexT provided clues to the interacting ligand structure. A DNase I footprinting assay of full-length MexT identified two MexT-binding sequence in the mexEF-oprN promoter. Our findings enhance the understanding of the regulation of MexT-dependent activation of efflux pumps.

• 한국습지학회지
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• 제20권2호
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• pp.116-123
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• 2018

산림생태계에서 대기로의 토양의 이동은 토양 호흡이라는 과정을 통해 이루어진다. 본 연구에서는 임령이 다른 잣나무림을 대상으로 생육기 동안의 토양 호흡값과 토양 내 뿌리의 양, 미생물 개체군 생물량을 측정하여, 토양호흡량이 임령에 따라 어떻게 다르며, 뿌리와 미생물 개체군이 얼마나 기여할 것인지 알아보고자 하였다. 토양 온도와 토양 호흡은 임령과는 상관없이 유사한 패턴을 보여 7월까지는 증가하고 이후 감소하였다. 산림의 임령이 높을수록 토양 호흡량이 대체적으로 높았다. 토양 내 뿌리와 미생물을 조사한 결과, 임령이 높을수록 토양 내 존재하는 지름 2 mm 이하인 세근의 양이 많았으며 토양 미생물 개체군의 생물량이 많았다. 토양에서 뿌리를 제거하였을 때 70년 숲은 변화가 없었으나, 40년 숲에서는 토양 호흡값이 감소하였다. 본 연구결과로 볼 때, 산림의 연령이 높아질수록 토양 호흡량이 커지며, 식물 뿌리와 특히 토양 미생물이 토양 호흡값에 많은 기여를 하고 있는 것으로 생각해 볼 수 있다.

• The Korean Journal of Physiology and Pharmacology
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• 제3권1호
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• pp.59-68
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• 1999

Chemically induced hypoxia has been shown to induce a depletion of ATP. Since intracellular free $Mg^{2+}\;([Mg^{2+}]_i)$ appears to be tightly regulated following cellular energy depletion, we hypothesized that the increase in $[Mg^{2+}]_i$ would result in $Mg^{2+}$ extrusion following hormonal stimulation. To determine the relation between $Mg^{2+}$ efflux and cellular energy state in a hypoxic rat heart and isolated myocytes, $[Mg^{2+}]_i,$ ATP and $Mg^{2+}$ content were measured by using mag-fura-2, luciferin-luciferase and atomic absorbance spectrophotometry. $Mg^{2+}$ effluxes were stimulated by norepinephrine (NE) or cAMP analogues, respectively. $Mg^{2+}$ effluxes induced by NE or cAMP were more stimulated in the presence of metabolic inhibitors (MI). Chemical hypoxia with NaCN (2 mM) caused a rapid decrease of cellular ATP within 1 min. Measurement of $[Mg^{2+}]_i$ confirmed that ATP depletion was accompanied by an increase in $[Mg^{2+}]_i.$ No change in $Mg^{2+}$ efflux was observed when cells were incubated with MI. In the presence of MI, the cAMP-induced $Mg^{2+}$ effluxes were inhibited by quinidine, imipramine, and removal of extracellular $Na^+.$ In addition, after several min of perfusion with $Na^+-free$ buffer, a large increase in $Mg^{2+}$ efflux occurred when $Na^+-free$ buffer was switched to 120 mM $Na^+$ containing buffer. A similar $Mg^{2+}$ efflux was observed in myocytes. These effluxes were inhibited by quinidine and imipramine. These results indicate that the activation of $Mg^{2+}$ effluxes by hormonal stimulation is directly dependent on intracellular $Mg^{2+}$ contents and that these $Mg^{2+}$ effluxes appear to occur through the $Na^+-dependent\;Na^+/Mg^{2+}$ exchange system during chemical hypoxia.

• 한국축산시설환경학회지
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• 제9권1호
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• pp.45-56
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• 2003

$TAO^{TM}$ System is an auto-heated thermophilic aerated digestion process using a proprietary microbe called as a Phototropic Bacteria (PTB). High metabolic activity results in heat generation, which enables to produce a pathogen-free and digested liquid fertilizer at short retention times. TAO$^{TM}$ system has been developed to reduce a manure volume and convert into the liquid fertilizer using swine manure since 1992. About 100 units have been installed and operated in Korean swine farms so far. TAO$^{TM}$ system consists of a reactor vessel and ejector-type aeration pumps and foam removers. The swine slurry manure enters into vessel with PTB and is mixed and aerated. The process is operated at detention times from 2 to 4 days and temperature of 55 to $65^{\circ}C$. Foams are occurred and broken down by foam removers to evaporate water contents. Generally, at least 30% of water content is evaporated, 99% of volatile fatty acids caused an odor are removed and pathogen destruction is excellent with fecal coliform, rotavirus and salmonella below detection limits. The effluent from TAO$^{TM}$ system, called as the "TAO EFFLUX", is screened and has superb properties as a fertilizer. Normally N-P-K contents of screened TAO Efflux are 4.7 g/L, 0.375 g/L and 2.8 g/L respectively. The fertilizer effect of TAO EFFLUX compared to chemical fertilizer has been demonstrated and studied with various crops such as rice, potato, cabbage, pumpkin, green pepper, parsley, cucumber and apple. Generally it has better fertilizer effects and excellent soil fertility improvement effects. Moreover, the TAO EFFLUX is concentrated through membrane technology without fouling problems for a cost saving of long distance transportation and a commercialization (crop nutrient commodity) to a gardening market, for example.

• Nutrition Research and Practice
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• 제2권4호
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• pp.211-217
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• 2008

This study was purposed to investigate the effect of onion or beet on plasma and liver lipids, erythrocyte Na efflux channels and platelet aggregation in simvastatin (SIM) treated hypercholesterolemic rats. Forty Sprague Dawley rats were divided into four groups and fed 0.5% cholesterol based diets containing 2 mg/kg BW simvastatin or simvastatin with 5% onion or beet powder. Plasma total cholesterol was significantly increased in SIM group compared with the control (p<0.01), and the elevated plasma total cholesterol of SIM group was significantly decreased in SIM-onion and SIM-beet groups (p<0.05). HDL-cholesterol in SIM-beet group was significantly increased compared with other groups (p<0.05). Platelet aggregation in both the maximum and initial slope was significantly decreased in SIM group compared with SIM-onion group (p<0.05). Na-K ATPase was significantly decreased in SIM group compared with the control, SIM-onion and SIM-beet groups (p<0.05). Na passive leak was significantly increased in all groups treated with SIM compared with the control (p<0.05). The total Na efflux was decreased in SIM group and increased in SIM-onion group and the difference between these two groups was significant (p<0.05). There was no difference in intracellular Na among groups. In present study, simvastatin, a HMG CoA reductase inhibitor at dose of 2mg/kg BW/day rather increased plasma total cholesterol in rats, inferring that the action mechanism of simvastatin on cholesterol metabolism differ between rat and human. Onion and beet play favorable roles in cardiovascular system by restoring the reduced Na efflux through Na-K ATPase and Na-K cotransport in SIM treated rats.

• Journal of Nutrition and Health
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• 제41권5호
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• pp.381-390
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• 2008

본 실험은 콜레스테롤식이와 운동수행이란 두 조건을 심순환기 질환의 관련지표로서 혈장 및 간의 지질, 적혈구막의 Na efflux 그리고 혈소판 응집성에 어떠한 영향을 미치는지 조사하였다. 운동에 의해서 체중이 다소 감소하였지만 그렇게 크지는 않았다. 라드를 주 지방원으로 사용한 식이에 0.5% 콜레스테롤첨가는 혈중 콜레스테롤을 2배 이상, 간 콜레스테롤을 8배 이상 증가시켰고 HDL-콜레스테롤을 절반 이하로 떨어뜨렸는데, 특히 운동효과로 예상했던 HDL-콜레스테롤증가는 대조군식이나 콜레스테롤식이에서 나타나지 않았다. 혈중 중성지방은 콜레스테롤 식이군에서 오히려 감소하였고 간의 경우 지방 축척으로 인해 간의 크 기뿐만 아니라 간의 중성지방은 현저히 증가되었다. 체액량 조절 및 혈압과 관계에서 조사된 적혈구의 Na efflux는 Na-K ATPase가 콜레스테롤 식이에 의해 그 활성을 감소되었고 운동이 이를 다소 회복시키는 경향을 보였다. 혈압과의 상관성이 높다고 알려진 Na passive leak은 콜레스테롤과 운동이 각각 독립적으로 증가시키는 요인으로 작용하여 콜레스테롤-운동군이 대조군식이-비운동군에 비해 현저히 증가된 것으로 나타났다. 총 Na efflux는 실험군 간에 큰 차이가 없었고 intracellular Na와의 상관성도 보이질 않았다. 혈소판응집성에 있어서 콜레스테롤식이가 혈소판 응집을 증가시키고 특히 운동이 초기응집을 증가시키는 경향을 보였다. 혈장 GOT 및 GPT수치는 콜레스테롤식이로 인해 현저히 증가됨으로서 간의 병리적 상태를 잘 반영하였고 운동에 의해 감소됨으로서 운동수행이 술이나 고지방식으로 인한 지방간을 호전시켜 줄 수 있으리라 기대할 수 있다. 고지혈증이나 고혈압 환자에 있어서 비약물적 요법으로 식이나 운동을 통한 치료나 예방의 가능성을 규명하기 위한 실험의 결과로서 특히 운동에 대해 일관되고 가시적인 효과가 미흡한 것은 6주간의 짧은 실험기간을 생각할 수 있는데 혈청 지질, Na flux 및 체액, 혈소판 응집성 등 심순환기 질환의 예방에 도움이 되는 운동의 형태나 강도 혹은 지속 기간에 대한 더 많은 연구가 필요하리라 생각된다.

• Journal of Microbiology and Biotechnology
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• 제18권4호
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• pp.658-662
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• 2008

Effects of pH shock on the secretion system of S. coelicolor A3(2) have been investigated at a transcriptional level by using DNA microarrays. Actinorhodin secretion was observed to be highly enhanced when an acidic-pH shock was applied to surface grown cultures of S. coelicolor A3(2). In this culture, a gene of actVA-orf1 encoding a putative efflux pump or transporter protein for actinorhodin was strongly upregulated. A major number of efflux pumps for other metabolites and a major number of secretion proteins for protein secretion were also observed to be upregulated with pH shock. The secretion of actinorhodin was observed to be remarkably enhanced in liquid culture as well.