• Archives of Pharmacal Research
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• 제25권6호
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• pp.747-758
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• 2002

The skin displays a highly active metabolism of polyunsaturated fatty acids (PUFA). Dietary deficiency of linoleic acid (LA), an 18-carbon (n-6) PUFA, results in characteristic scaly skin disorder and excessive epidermal water loss. Although arachidonic acid (AA), a 20-carbon (n6) PUFA, is metabolized via cyclooxygenase pathway into predominantly prostaglandin $E_2(PGE_2)$ and $PGF_{2{\alpha}}$, the metabolism of AA via the 15-lipoxygenase (15-LOX) pathway, which is very active in skin epidermis and catalyzes the transformation of M into predominantly 15S-hydroxyeicosatetraenoic acid (15S-HETE). Additionally, the 15-LOX also metabolizes the 18-carbon LA into 13S-hydroxyoctadecadienoic acid (13S-HODE), respectively. Interestingly, 15-LOX catalyzes the transformation of $dihomo-{\gamma}-linolenic$ acid (DGLA), derived from dietary gamma-linolenic acid, to 15S-hydroxyeicosatrienoic acid (15S-HETrE). These monohydroxy fatty acids are incorporated into the membrane inositol phospholipids which undergo hydrolytic cleavage to yield substituted-diacylglycerols such as 13S-HODE-DAG from 13S-HODE and 15S-HETrE-DAG from 15S-HETrE. These substituted-monohydroxy fatty acids seemingly exert anti-inflammatory/antiproliferative effects via the modulation of selective protein kinase C as well as on the upstream/down-stream nuclear MAP-kinase/AP-1/apoptotic signaling events.

• 센서학회지
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• 제26권6호
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• pp.420-426
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• 2017

A colorimetric sensor was investigated to achieve a low-cost warning device for harmful gaseous formaldehyde (HCHO). The sensor is based on selective reactions between hydroxylamine sulfate and HCHO, leading to the production of sulfuric acid. The produced acid results in color-changing response through the acid-base reaction with dye molecules impregnated on a solid membrane substrate. For attaining this purpose, sensors were fabricated by drop-casting a dye solution prepared using different pH indicators on various commercially available polymer sheets, and their colorimetric responses were evaluated in terms of sensitivity and reliability. The colorimetric sensor using bromophenol blue (BPB) and nylon sheet was found to exhibit the best performance in HCHO detection. An initial bluish green of a sensor was changed to yellow when exposed to gaseous formaldehyde. The color change was recorded using an office scanner and further analyzed in term of RGB distance for quantifying sensor's response at different HCHO(g) concentrations. It exhibited a recognizable colorimetric response even at 50 ppb, being lower than WHO's standard of 80 ppb. In addition, the sensor was found to have quite good selectivity in HCHO detection under the presence of common volatile organic compounds such as ethanol, toluene, and hexane.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1997년도 춘계학술대회
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• pp.119-119
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• 1997

Valacyclovir is a L-valyl ester prodrug of acyclovir which is a highly effective and selective antiviral agent in the treatment of herpes virus diseases. Valacyclovir is rapidly and almost completely converted to acyclovir and increases the oral bioavailability of acyclovir three to five fold. However, the intestinal absorption mechanism of valacyclovir is not clear. If the improved absorption mechanism of valacyclovir is fully understood, it will provide a rationale of designing the amino acid ester prodrugs of polar drugs containing hydroxyl group. The main objective of our present study is to characterize the membrane transport mechanism of valacyclovir. Methods : Intestinal absorption of valacyclovir was investigated by using in-situ rat perfusion study and its wall permeability was estimated by modified boundary layer model. The membrane transport mechanism was also investigated through the uptake study in Caco-2 cells and in CHO-hPepTl cells. Results : In the rat perfusion study, the wall permeability of valacyclovir was ten times higher than acyclovir and showed concentration dependency, Valacyclovir also demonstrated a D,L stereo-selectivity with L-isomer having an approximately five-fold higher permeability than D-isomer. Mixed dipeptides and cephalexin, which are transported by dipeptide carriers, strongly competed with valacyclovir for the intestinal absorption, while L-valine did not show any competition with valacyclovir. This indicated that the intestinal absorption of valacyclovir could be dipeptide carrier-mediated. In addition, the competitive uptake study in Caco-2 cells presented that dipeptides reduced the valacyclovir uptake but valine did not. Also, in IC$\sub$50/ study, valacyclovir showed strong inhibition on the $^3$H-gly-sar uptake in CHO-hPepTl cells over-expressing a human intestinal peptide transporter. Taken together, the result from our present study indicated that valacyclovir utilized the peptide transporter for the intestinal absorption.

• The Korean Journal of Physiology and Pharmacology
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• 제6권3호
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• pp.165-169
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• 2002

We have previously demonstrated that phytoestrogens isolated from safflower seeds significantly attenuated bone loss in ovariectomized rats, and directly stimulated proliferation and differentiation of cultured osteoblastic cells. In an attempt to elucidate underlying cellular mechanisms, in the present study we investigated effects of $17{\beta}-estradiol\;(E_2)$ and phytoestrogens such as matairesinol and acacetin, a type of lignan and flavonoid, respectively, on activation of mitogen activated protein (MAP) kinases, extracellular signal-regulated kinase 1 (ERK1) and ERK2, in cultured osteoblastic ROS 17/2.8 cells. Western blot analysis with anti-MAP kinase antibody showed that a wide range concentrations $(10^{-14}\;to\;10^{-6}\;M)\;of\;E_2$ as well as both phytoestrogens induced rapid and transient activation of ERK1/2 through phosphorylation within minutes. Maximum activation of MAP kinases by $E_2$ and phytoestrogens were observed at 10 and 15 min, respectively. $E_2-induced$ phosphorylation of ERK1/2 returned to the control level at 30 min, whereas phytoestrogen-induced phosphorylation was maintained at high level until 30 min. PD-98059, a highly selective inhibitor of MAP kinase, prevented phosphorylation of ERK1/2 in the cells treated either with $E_2$ or phytoestrogens. To examine a possible involvement of estrogen receptor in the activation process of MAP kinase, Western blot analysis was performed in the presence and absence of the estrogen receptor antagonists, ICI 182,780 and tamoxifen. These antagonists blocked MAP kinase phosphorylation induced not only by $E_2,$ but also by the phytoestrogens. To the best our knowledge, this study is the first to demonstrate that phytoestrogens such as flavonoid and lignan extracted from safflower seeds produce a rapid activation of MAP kinase, at least partially via membrane estrogen receptor of the cultured osteoblastic cells.

• Journal of Biosystems Engineering
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• 제35권5호
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• pp.343-349
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• 2010

Rapid on-site sensing of nitrate-nitrogen and potassium ions in hydroponic solution would increase the efficiency of nutrient use for greenhouse crops cultivated in closed hydroponic systems while reducing the potential for environmental pollution in water and soil. Ion-selective electrodes (ISEs) are a promising approach because of their small size, rapid response, and the ability to directly measure the analyte. The capabilities of the ISEs for sensing nitrate and potassium in hydroponic solution can be affected by the presence of other ions such as calcium, magnesium, sulfate, sodium, and chloride in the solution itself. This study was conducted to investigate the applicability of two ISEs consisting of TDDA-NPOE and valinomycin-DOS PVC membranes for quantitative determinations of $NO_3$-N and K in hydroponic solution. Nine hydroponic solutions were prepared by diluting highly concentrated paprika hydroponic solution to provide a concentration range of 3 to 400 mg/L for $NO_3$-N and K. Two of the calibration curves relating membrane response and nutrient concentration provided coefficients of determination ($R^2$) > 0.98 and standard errors of calibration (SEC) of < 3.79 mV. The use of the direct potentiometry method, in conjunction with an one-point EMF compensation technique, was feasible for measuring $NO_3$-N and K in paprika hydroponic solution due to almost 1:1 relationships and high coefficients of determination ($R^2$ > 0.97) between the levels of $NO_3$-N and K obtained with the ion-selective electrodes and standard instruments. However, even though there were strong linear relationships ($R^2$ > 0.94) between the $NO_3$-N and K concentrations determined by the Gran's plot-based multiple standard addition method and by standard instruments, hydroponic $NO_3$-N concentrations measured with the ISEs, on average, were about 10% higher than those obtained with the automated analyzer whereas the K ISE predicted about 59% lower K than did the ICP spectrometer, probably due to no compensation for a difference between actual and expected concentrations of standard solutions directly prepared.

• 청정기술
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• 제23권1호
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• pp.1-14
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• 2017

높은 농도의 질산염을 포함하는 물은 인간의 건강을 위협하고 부영양화의 원인이 되기 때문에 제한 농도 이하로 처리되어야 한다. 그러나 질산염은 수용액에서의 높은 용해도로 인해 응집, 여과 및 침전과 같은 일반적인 처리공정으로는 제거가 거의 불가능하다. 따라서 흡착, 이온교환, 역삼투, 탈질과 전기투석과 같은 다른 기술이 질산염의 효과적인 제거를 위해 요구된다. 이들 각 기술은 비용, 수질 개선 정도, 잔류물 처리와 전처리 요구와 같은 인자의 비중에 따라 장점과 단점과 가능성을 가지고 있다. 흡착은 가격 효율성, 운전의 용이성과 설계의 간편성으로 가장 보편적으로 사용되는 공정이다. 흡착제의 표면개질은 질산이온 흡착능력을 개선하였다. 역전 전기투석과 역삼투의 질산-선택 멤브레인 공정은 수용액 중의 질산이온 제거에 오랜 동안 많은 지역에서 효과적임이 증명되었다. 두 기술은 높은 농도의 폐기물을 생성하고 이것의 신중한 처분이 필요하다.

• 멤브레인
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• 제9권4호
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• pp.230-239
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• 1999

운반체(감응물질)로 제 4급 인산염을 사용하여 PVC를 지지체로 하여 과염소산이온의 농도 $10^{-6}$ M까지 선형적인 이온선택성 전극을 제작하였다. 운반체의 화학적구조와 함량 가소제의 종류 및 막 두께에 따른 전극의 기울기 선형응답범위 및 한계측정농도 등 전극전위특성을 고려하여 최적의 과염소산 이온선택성 PVC막 전극을 제조한 다음 측정 가능한 pH 범위 선택계수 및 전극의 교류임피던스 특성을 비교 검토하였다 운반체로 tetraoctyl-phosphonium perchlorate(TOPP) tetraphenylphosphonium perchlorate(TPPP) 및 tetrabutylphosponium perchlorate (TBPP)_ 등의 제 4급 인산염의 과염소산 이온 치환체를 사용하였다 알킬기의 탄소고리 수가 증가할수록 전극특성은 TBPP$^P{ClO}_4$, 선형응답범위 $10^{-1}$\times$10^{-6}$ M 및 한계측정농도는 9.66$\times$$10^{-7}$ M 이었으며 시판되고 있는 Orion 전극특성보다 좋은 결과를 나타내었다 전극전위는 pH3~11범위에서 ph의 영향을 받지 않았으며 ${CIO}_4$ 에 대한 방해이온의 선택계수 서열은 ${SO}^2_4$ < F < Br < I 이었다 임피던스 측정결과 TOPP의 경우 등가회로는 용액저항 이중층용량과 벌크저항의 병렬 및 Warburg 임피던스의 직렬이었다 이 경우 용액저항은 거의 나타나지 않았고 확산에 의한 Warburg 임피던스는 크게 나타났으며 Warburg 계수는 1.32$\times$$10^74 $\Omega$ $\cdot$ ${cm}^2/s^{1/2}$이었다.

• 한국환경과학회지
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• 제23권5호
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• pp.943-962
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• 2014

Industrial gas drying, dilute gas mixtures purification, air fractionation, hydrogen production from steam reformers and petroleum refinery off-gases, etc are conducted by using adsorptive separation technology. The pressure swing adsorption (PSA) has certain advantages over the other methods, such as absorption and membrane, that are a low energy requirement and cost-effectiveness. A key component of PSA systems is adsorbents that should be highly selective to a gas being separated from its mixture streams and have isotherms suitable for the operation principle. The six standard types of isotherms have been examined in this review, and among them the best behavior in the adsorption of $CO_2$ as a function of pressure was proposed in aspects of maximizing a working capacity upon excursion between adsorption and desorption cycles. Zeolites and molecular sieves are historically typical adsorbents for such PSA applications in gas and related industries, and their physicochemical features, e.g., framework, channel structure, pore size, Si-to-Al ratio (SAR), and specific surface area, are strongly associated with the extent of $CO_2$ adsorption at given conditions and those points have been extensively described with literature data. A great body of data of $CO_2$ adsorption on the nanoporous zeolitic materials have been collected according to pressure ranges adsorbed, and these isotherms have been discussed to get an insight into a better $CO_2$ adsorbent for PSA processes.

• 공업화학
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• 제3권2호
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• pp.349-359
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• 1992

염료속에 함유된 무기염(NaCl, $Na_2SO_4$)의 선택적 제거를 위해 역확산과 역삼투를 결합한 방법과 nanofiltration(NF)을 각각 이용하였다. 역확산에 의한 염의 제거율은 염의 종류에 따라 1회(one pass)에 1~30%를 나타냈으며 염과 염료의 분리비는 10~500의 매우 큰 값을 갖는 반면 염료의 손실율은 0.3% 이하였다. 염료용액을 순환시킬수록 음이온인 $Cl^-$ 이온의 제거율이 증가하고 양이온인 $Na^+$ 이온의 제거율이 감소하는 도난투석현상이 관찰되었다. 또한 공급용액의 유속이 염의 제거에 미치는 영향을 살펴보았다. 역확산에 의해 염이 제거된 염료를 평판형 역삼투막을 사용하여 농축하였으며 $Cl^-$ 이온의 배제율을 solution-diffusion 모델식에 적용하였다 2회의 Diafiltration(DF)을 수행한 NF에서도 역확산에서와 마찬가지로 도난투석에 의해 $Cl^-$ 이온의 배제율 감소와 음배제율을 관찰하였다. 특히 두번째 DF에서 도난투석의 효과는 더욱 크게 나타났다.

• 대한의생명과학회지
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• 제15권3호
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• pp.199-205
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• 2009

This study was designed to investigate direct effects of [D-$Pen^2$, D-$Pen^5$]-enkephalin, a $\delta$-opioid receptor agonist on the neuronal activity of medial vestibular nuclear (MVN) neurons by whole-cell configuration patch clamp experiments. The spike frequency of MVN neuron was increased to $9.50{\pm}0.55$ (P<0.05) and $10.56{\pm}0.66$ (P<0.05) by 5 and $10{\mu}M$ [D-$Pen^2$, D-$Pen^5$]-enkephalin from the control level of $8.05{\pm}0.55$ spikes/sec, respectively (n=18). The resting membrane potential of the neurons was increased to $-37.86{\pm}0.92$ and $-36.97{\pm}0.97$ (P<0.05) from $-38.74{\pm}1.13\;mV$ by 5 and $10{\mu}M$ [D-$Pen^2$, D-$Pen^5$]-enkephalin, respectively. The amplitude of afterhyperpolarization was decreased to $23.78{\pm}0.65$ and $21.67{\pm}0.89$ (P<0.05) from $23.73{\pm}0.53\;mV$ by 5 and $10{\mu}M$ [D-$Pen^2$, D-$Pen^5$]-enkephalin, respectively. The spike width was changed to $2.22{\pm}0.08$ and $2.24{\pm}0.07$ from $2.20{\pm}0.08\;mV$ by 5 and $10{\mu}M$ [D-$Pen^2$, D-$Pen^5$]-enkephalin, respectively. After pretreatment of naltrindole, a highly selective 8-opioid receptor antagonist, [D-$Pen^2$, D-$Pen^5$]-enkephalin did not change firing rate, resting membrane potential, afterhyperpolarization amplitude, and spike width of MVN neurons. The above experimental results suggest that [D-$Pen^2$, D-$Pen^5$]-enkephalin increases the neuronal activity of MVN neurons via inhibition of calcium-dependent potassium currents underlying the afterhyperpolarization.